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CT-Expo V 2.3

1. ES gt rr E aleje amy my ad 3818 12 2 aia e ES 3 amp ES E BE ES 2 xe Fr o 0 o t gt ES 2 ES 3 ES le o o S ES ES a a S E X a oju Pr lo Eu or BE w w lt i N a EN D a d pen E m a D a z 3 ES g laeh Fig 7 8 Results of protocol optimisation for the example given in fig 7 1 7 7 Adjustments have been made for the parameters tube voltage U tube current I and slice collimation h_ only User s Guide CT Expo V 2 3 Application Module Benchmarking of the survey average by increasing the mAs prod uct For some types of examination with good inherent contrast e g facial bone sinuses chest pelvis os seous pelvis thoracic and abdominal aorta a fur ther dose reduction is possible This arises from the observation that the average values of the CT survey for these anatomical regions are still in need of optimisation in accordance with the ALARA princi ple Consequently the mAs settings have further been reduced for these examinations The result of this optimisation procedure is shown in fig 7 8 All other scan parameters tube voltage ac quisition time table feed scan length number of series have been kept unchanged Optimisation can lead to a reduction in average dose levels to 46 of the survey CTDI and to 38 of the survey DLP
2. A comparison of the slice thickness fig 7 7d shows that in most anatomical regions the values applied are higher than the survey values Slice thickness has an indirect impact on the dose because image noise increases when collimation is narrowed Working with reduced slice thickness might give rise to an increase in kV and mAs in order to limit the effect of increased noise The comparison of actual slice thick nesses and corresponding survey values shows that there is no reason to increase dose except for the ex aminations facial bone neck and cervical spine In summary above average dose values at this par ticular institution are primarily caused by mAs set tings which have not been reduced in accordance with the increase in kV and by not making use of higher values of pitch The optimisation of these CT protocols includes reduction of tube voltage settings to 120 kV in general and to 80 kV in CT angiography incresed iodine contrast reduction of mAs settings to a level which gives a relative CTDI value of between 60 and 70 of the survey level and which is typical for other modern spiral scanners increasing the pitch factor to 1 5 except for stand ard brain cervical spine and lumbar spine this can be accomplished by preferentially reducing the slice thickness accordingly while keeping the ta ble feed and the new mAs settings unchanged Conversely the dose values for the examination type Facial B
3. Benchmarking of MSCT Scanners The benchmarking of MSCT scanners closely resem bles the procedure described for SSCT scanners In order to account for the particularities of MSCT scan ners one additional column has been introduced Fur thermore the graphical presentation of the results has been modified in two essential aspects Step 1 Selection of Scanner Model The selection of the scanner model is made in the same way as for SSCT scanners Step 2 Effective Dose Calculation Mode The calculation of effective dose can be performed either according to the previous method ICRP 60 ICRP 1991 or the new method ICRP 103 ICRP 2008 by activating the corresponding button Step 3 Selection of Examination Type A selection of the type of examination is made auto matically as for SSCT scanners by entering the required data into the corresponding line 4 User s Guide CT Expo V 2 3 Application Module Benchmarking Step 4 Input of Scan Parameters E oe eee eee Ue othe A e Ser Spiral Dose Abbr kv mA s mAs mAs mm mm mm mode modul 120 300 0 5 150 100 Dis 4 5 The input of the scan and examination parameters is mostly made in a similar way to that used for SSCT scanners However some important modifications should be observed fig 7 9 o m E XI lt I Sis 8 a7 apa paja vlan ala aa a al ary los on xl xl e the number N of
4. 67 67 41 65 53 58 23 76 79 30 40 23 23 94 94 94 female from 77 75 74 71 66 39 34 23 0 5 23 0 5 0 5 57 12 38 12 46 39 38 71 68 65 22 22 0 to 89 77 85 75 84 65 65 65 41 41 41 23 23 64 64 89 63 63 39 61 51 56 21 72 75 28 38 21 21 89 89 89 50 User s Guide CT Expo V 2 3 Appendices Appendix D Accuracy of Dose Calculations The accuracy of the dose calculations made with CT Expo depends on a number of factors In this appen dix these factors are described and the resulting er rors are stated Data Input Incorrect input of the required data type of scanner scan range examination type scan and examination parameters may result in considerable errors There fore all data should be input carefully Detailed in formation on items to be observed with each input parameter is given in section 4 Scanner Data The accuracy of the scanner data directly affects the calculation of all dose quantities Potential sources of error are output exposure tolerances of the type of scan ner ranging typically from 10 to 30 e unknown modifications to the type of scanner re lating e g to beam filtration beam shaper colli mation etc The authors of CT Expo in co operation with the scanner manufacturers are attempting to keep the scanner database up to date and to supply all regis tered users with actual values The most ac
5. Note Slice collimation denotes the setting used for data acquisition not that used for retrospec tive reconstruction On some scanners e g GE LightSpeed QX i the user primarily selects the slice thickness h of the reconstructed im age the collimation which is used for data ac quisition is then applied automatically For dose calculations with CT Expo only the actual ac quisition slice collimation must be used Infor mation on the rules that apply for automatic collimator settings may be obtained from the user s manual or from the scan parameter trans lator given in the appendix Otherwise the dose adjustment for overbeaming effects very im portant for the narrow collimations preferred in MSCT will not work correctly speed in mm s These two values are only iden tical for rotation times of 1 s If the rotation time differs from 1 s you should multiply the table speed by the rotation time to obtain the correspond ing table feed Please enter zero if stationary pro cedures are performed e g CT fluoroscopy Note On multi slice scanners also on dual slice scan ners such as Elscint TWIN please always use the actual table feed e g TF 10 mm for N 2 h 5 mm and pitch p 1 contiguous scan ning Please make use of the scan parameter translator given in the appendix if the table feed is not displayed explicitly e Series Please enter the number of scan series e g unenhanced contras
6. Calculation Formulas Weighted CTDI kU H B CTDI a e CTDI u18 a I sts kog j j U nef CTDI for scan projection radiogram as CTDI but witht N h col TS Voltage correction factor k UHIB uny U Dy tip Overbeaming correction factor N A N ha dz k Z ref N ha N h dz ref Volume CTDI Effective CTDI CTDI CTDI CPP Pitch _ _IF P N h Dose length product DLP CTDI cA A CTDT E Lor Total scan length La first last slice position h AL tot Overranging spiral scanning mode only AL N ha mor pt bor Effective dose DLP 1 lt E ER w H B k m 4 z Pasz CT H B Zaz 21 Uterine dose CTDI lt Deters a j keran X f Uterus z HIB 49 User s Guide CT Expo V 2 3 Appendices Appendix C Types of Standard Examinations Tab C 1 Standard examinations with specification of the anatomical and geometrical limits of the scan range Standard Examination Name Routine Brain Skull Base Facial Bones Sinuses Dental Facial Bones Neck Routine Chest Chest Incl Adrenals Chest Upper Abdomen Routine Abdomen tot Routine Abdomen w Testes Liver Kidneys Upp Abdomen Routine Pelvis Routine Pelvis w Testes Whole Trunk Whole Trunk w Testes CTA Carotid CTA Aorta CTA Thoracic Aorta CTA Abdominal Aorta CTA Pulmonary Vessels Coronary CTA Coronary Bypass CTA CTA Periphe
7. ICRP 1997 ICRP 2008 International Commission on Radiological Pro tection 1990 Recommendations of the Interna tional Commission on Radiological Protection Publication 60 Oxford Pergamon Press 1991 International Commission on Radiological Pro tection Conversion coefficients for use in radio logical protection against external radiation Pub lication 74 Ann ICRP 1997 Vol 26 3 International Commission on Radiological Pro tection The 2007 recommendations of the Inter national Commission on Radiological Protection Publication 103 Ann ICRP 2008 Vol 37 2 4 1 332 Nagel 2002 Nagel HD ed Galanski M Hidajat N Maier W Schmidt Th Radiation exposure in computed tomography fundamentals influencing param eters dose assessment optimisation scanner data terminology 4th revised and updated edi tion Hamburg CTB Publications 2002 Mail ctb publications gmx de 58 User s Guide CT Expo V 2 3 Literature Nagel 2010 Nagel HD Guideline for the optimization of the NIH 1999 radiation exposure of CT ecaminations 2nd re vised and updated edition 2010 Download www sascrad com pagel3 php National Institute of Radiation Hygiene CT dose calculation software CT Dose Herlev National Institute of Radiation Hygiene 1999 Mail ctdose sis dk Shrimpton 1991 Shrimpton PC Jones DG Hillier MC Wall BF LeHeron JC and Faulkner K Survey of CT Practice in the UK Part 2 Dosimetr
8. Siemens Somatom DRH The dose characteristics for this older type of scanner differ substantially from other CT scanners In order to cor rect for scanner specific calculations of organ dose and effective dose discrete correction factors in steps of between 10 and 20 are used Scanner Match ing The error resulting from this procedure amounts to approximately 10 and thus remains at a level comparable to other factors influencing the accuracy of effective dose determined by this calculation Dose Modulation On most types of scanner the tube current can be adjusted automatically to the varying absorption be tween a p and lateral projections angular dose modu lation or and along the patient s long axis longitu 54 User s Guide CT Expo V 2 3 Appendices 20 o 20 40 z Position cm Fig D 1 The mAs profiles used in CT Expo to correct for dose modulation effects in dependence of the slice location from feet left to head right dinal dose modulation With respect to dose assess ment this is important only when calculating organ dose and effective dose As far as effective dose is concerned differences in the radiation intensity with projection angle and or location should be compensated approximately This applies for most types of examination except those that comprise trunk plus head or legs e g CTA of the carotides or peripheral run off No compensa tion effects however can be expecte
9. identify whether the indicated value of tube current or mAs product refers to the time averaged value or to the unmodulated nominal value If the latter should apply the tube current must be corrected according to the duty cycle This depends on the design proper ties of this feature and the patient s heart rate Total collimation N h On single slice scanners i e the number N of slices per rotation 1 this is the same value as the nominal slice thickness h in mm On some scanners an effective slice thickness is displayed in spiral mode this is al ways greater than the slice thickness that results from the selected collimation and leads to incor rect values of dose length product and effective dose when these quantities are calculated There fore only the correct geometrical slice collimation must be used which results from the collimator settings if the same scan would be performed in 14 User s Guide CT Expo V 2 3 Application Module Calculate sequential mode see also scan parameter transla Table feed TF Please enter the distance which tor given in the appendix For multi slice scan the table travels from slice position to slice posi ners N gt 1 always enter the total collimation tion in sequential mode or per rotation in spiral i e the product N h of slice collimation h and mode Please do not mix up table feed with table the number N of slices acquired simultaneously
10. in head or body scanning mode depend ing on the scanner and the protocol settings As the displayed dose values are based on the correspond ing standard phantom diameter 16 and 32 cm re spectively the adequate type of examination has to be selected Otherwise the calculated dose values will be too high or too low by a factor of 2 Location and length of the selected scan range are indicated on the phantoms ADAM and EVA for in formation as shown in fig 6 1 but cannot be modi 27 User s Guide CT Expo V 2 3 Application Module Light la E BE u E mE u SS m BE E m oS BE BE LY RZ LL La ES BE A Las E _ Ls E mE La E Fig 6 1 Indication of the selected scan range here abdomen with pelvis fied Equally the corresponding values of scan length and scan range limits co ordinates and anatomical landmarks are displayed but for information pur poses only Step2 Input of CTDI and DLP For this purpose the corresponding values referring to a single scan series not to the entire examination must be typed in They can be obtained either from the scan console or from the dose report of the pertain ing examination The input fig 6 1 is made in terms of the customary units mGy and mGy cm Fig 6 2 Input of the CTDI y and DLP values provided by the scanner 28 User s
11. of Scan Parameters The input of both the scan and examination param eters is made in a similar way to the Calculate mod ule The only differences fig 5 5 are Please Enter Actual Settings 3 Qhee Chot N Hoot mms _ m s mAs mm Fig 5 4 Input cells in white used for entering the actual scan projection radiograph parameters Alternatively to tube current I and table speed TS the SPR s total mAs can be typed into dell Q _ 22 User s Guide CT Expo V 2 3 Application Module Standard e Data input for each scan series separately e the input of the number of scan series is no longer required e the input of a scan length which differs from the pre defined values is possible Once the scan length cells that have been altered are reset to zero the default scan length applies again The corresponding check boxes must be activated if a series is scanned in spiral mode and or with longi tudinal or 3D dose modulation Calculation of effec tive dose is than performed according to the mAs characteristic shown in fig D1 in the appendix Scan Parameters X for up to 3 series t Qar Q s mAs mAs 1st Series 2nd Series 3rd Series x x x Uns Figo TF ud p Kos In the cells k the overbeaming correction factors for each series are displayed following the data input made in the cells N h and I r or Q In the cells AL the extent of overbeaming is sho
12. scan param eters This was particularly true for tube load mAs slice thickness table feed and pitch With MSCT this is no longer the case CT Expo however is designed as a universal tool independent of a particular type of scanner Therefore we have introduced a section named MSCT Scan Parameter Translator to assist in the evaluation of MSCT scan protocols By making use of this aid the parameters displayed according to the scanner manufacturer s phi losophy can be converted into the uniform set of input parameters required in CT Expo Acquisition time t Please enter the scan time per slice in sequential slice by slice mode or the rotation time in spiral mode For some older scanners which operate in pulsed mode e g Tomoscan CX S the scan time must be corrected by the duty cycle i e pulse length divided by the sum of pulse and interval length If your scanner only displays the total scan time T in spiral mode you have to divide this by the number of rotations made Current time product Q If you have not entered mA and s separately please enter the mAs prod uct per slice in sequential mode or per rotation in spiral mode If your scanner only displays the total mAs product in spiral mode you should di vide this by the number of rotations made How ever this will not be feasable if the total mAs prod uct also includes the contribution of the scan pro jection radiograph From our earlier ex
13. slices acquired simultaneously has to be entered in a separate column the corresponding check box has to be activated in order to enable the correction of the effective dose values if the examination has been performed with longitudinal or 3D dose modulation e the presentation of scan parameters tube current slice collimation reconstructed slice thickness pitch largely differs between the scanner manu facturers Please make use of the scan parameter Fig 7 9 Input of MSCT scan parameters for each type of ex translator given in the appendix amination column N has been added and correction for dose modulations effects can be applied by activating the cor responding check box Take care of the pitfalls resulting from non uniform presentation of scan parameters at the scanner consoles of different manufacturers Make use of the scan pa Relative and absolute dose values are presented in rameter translator in the appendix the same way to that used for SSCT scanners Please a a a al al a al in xl xl o al a a7 q a al ae aaa testy 121 0 10 0 206 177 15012 220828 12 20411 d Results User s Guide CT Expo V 2 3 Application Module Benchmarking note that reference is made to the average dose val ues of the 99 survey on SSCT practice Bench marking with respect to the results of the MSCT sur vey in 2002 is not appropriate as curr
14. the Calculate mod ule Please review the explanations against each pa rameter given in section 4 The only differences fig 7 5 are separate lines for head and body scanning mode are provided for CT examinations located in the neck region They should be used according to the scanning mode applied e the length of the scan region Scan Length which is typical at the particular institution should be entered into column L Scan Length from first to last slice position input in cm Please take care not to mix up the scan length with the length of the scan projection radiograph SPR also known as Scanogram Scout View Topo gram etc This is normally taken for localisation purposes before carrying out the scan procedure The dose contribution of the SPR is normally negligible 33 User s Guide CT Expo V 2 3 Application Module Benchmarking Scan Parameters U l fp iver tee ie a A Ik mA s mAs mAs mm mm mm 120 200 15 300 300 10 12 410 Example Routine Brain BRN 140 206 x Relative Values CTD CTDho DLPy E in of Survey Average Dose Values Spiral CTDly CTDlo DLPy ES mGy mGy nGy cr mSv Scan per Examination per Peso 660 var 16 mau men 00 on Ser Facial Bone Sinuses FB SIN 120 170 Facial B Neck Head FB N H FB N B 72 912 305 12 sim 1000 00 00 allen Routine Chest C
15. to assess effective and organ doses for pre defined standard CT examinations adults only independent from the type of scanner Only the CTDI and DLP values that are meanwhile provided on most scanners are required e Benchmarking Provides dose calculations for the complete spectrum of standard CT examinations adults only and allows comparison with the re sults of the German CT survey in a single sheet The graphical display is useful in allowing analy sis of any significant difference The results may be used for subsequent optimisation of scan pro tocols CT Expo V 2 3 has an intuitive and clearly structured user interface In this manual a comprehensive de scription is given of each sheet and the application steps involved Basic knowledge how to work with MS Excel is required but not advanced skills be cause all operations below the user interface work automatically Also required is knowledge of CT spe cific dose descriptors terms and abbreviations In formation on these and the underlying computa tional formulas may be obtained from the book mentioned in the beginning of this introduction Nagel 2002 User s Guide CT Expo V 2 3 Start Sheet 2 Start Sheet When opening the CT Expo V 2 3 file first a box appears in which the user is requested to activate mac ros Please click the button Activate Macros to start the application In Excel version 2007 and later mac ros must be enabled is t
16. 0 User s Guide CT Expo V 2 3 Application Module Benchmarking 7 Application Module Benchmarking Application Areas The Benchmarking module enables you to bench mark the scan protocols for the entire set of 14 stand ard CT examinations which were analysed in the German surveys on CT exposure practice Galanski 2001 and Brix 2002 You will be able to assess the dose values resulting from the exposure practice at this particular hospital or medical practice and to re ceive an indication how these values compare with the survey outcomes Although this survey was re stricted to German CT users it is likely that CT prac tice is quite similar in other countries too With the aid of additional diagrams you will be able to easily identify those parameter settings which sig nificantly differ from common practice and which may give rise to increased dose values This module should be used e to evaluate the pre programmed scan protocols when a new scanner is installed e after each modification of scan protocols to document the exposure practice at this particu lar installation when required by internal and ex ternal audits The design of this module is identical with that used in the feedback actions at the beginning of 2001 sin gle slice CT survey and in the middle of 2002 multi slice CT survey which provided feedback to all par ticipants of the German CT surveys about their per sonal res
17. 2 1063 184 227 Effective dose E refers to ICRP 60 os om am os ee en Fig 5 8Dose values for the complete examination given in absolute terms as in fig 5 6 and in relative terms using as a com paritor the average values per examination ofthe German CT survey Values exceeding 100 are marked red and indicate actual dose values greater than the average of the survey values 26 User s Guide CT Expo V 2 3 Application Module Light 6 Application Module Light Application Areas The Light module offers a simplified calculation method with pre defined standard CT examinations of standard sized adults The calculation can be per formed independent from the type of scanner in use and only requires the corresponding CTDI and DLP values These are meanwhile provided by most scanners Hence only effective and organ doses re main to be assessed This module should be used e if the complete set of scan protocol data required for CT Expo is not fully available e if a quick assessment of effective and organ doses with a satisfactory accuracy 1s acceptable Input Steps Step 1 Selection of Examination Type The definition of the scan range is performed as in module Standard by selecting the examination type from the drop down menu shown in fig 5 1 Exami nations that are restricted to the neck region facial bones neck carotide CTA cervical spine can be made either
18. 57 Dicke a p cm 20 Gewicht kg 70 53 User s Guide CT Expo V 2 3 Appendices equal dose relevant characteristics Siemens Soma tom DRH No information is available up to now on the agreement with other data sets e g NIH 1999 In addition to the conversion factors used the accu racy of effective dose is also dependant on how these factors are used in the calculation This applies to the way in which organs are substituted which are listed in reports ICRP 60 ICRP 1991 and ICRP 103 ICRP 2008 but not available in the pertaining data set as well as the correct treatment of the remain der organs In CT Expo a simplified accelerated procedure is used in the Calculate module which takes the remainder organs into account slice by slice The Standard Light and Benchmarking modules however make use of pre defined mean conversion factors which have been determined by using a more extended procedure which treats the remainder or gan problem per anatomical region Normally the results of these two different approaches differ by less than 5 except for the region Facial Bone Neck where differences can be up to 10 However the effective dose values which are typical for this anatomical region are small relative to e g thorax and abdomen and hence this error can be tolerated Correction of Scanner Type The conversion factors used in CT Expo apply for the scanner model
19. Guide CT Expo V 2 3 Application Module Light Step 3 Correction for dose modulation effects A correction of the calculated organ and effective dose values can be applied by activating the check box fig 6 3 if the examiation has been carried out with longitudinal or 3D dose modulation The correction is based on the modulation characteristic shown in the appendix fig D1 Step 4 Results The results of the calculation are displayed in terms of effective dose according to both ICRP 60 and 103 as well as doses to all relevant organs and tissue listed in ICRP The agreement between the calculations made in application modules Light and Calculate is usually within 10 provided that identical scan ranges size and location are used and overranging amounts to approximately 4 cm 2 cm for head scans 3 Application of Automatic Dose Control M Longitudinal z axis dose modulation Fig 6 3 Activation of the dose modulation correction Fig 6 4 Effective and organ doses for the dose values from fig 6 2 examination abdomen with pelvis 29 User s Guide CT Expo V 2 3 Application Module Light If the gross scan length derived from CTDI and DLP turns out significantly longer or shorter by or 3 cm than the corresponding standard length for the selected examination plus 4 cm overranging a warning message appears In this case the accuracy of the calculated doses in particular fo
20. HE a Routine Abdomen tot ABD PE xl N e D a Routine Pelvis xl N o E Liver Kidneys LIKI Whole Trunk TRUN TH E ES D alrm s aja tnd D ak a o ES a 2 5 ae Lja a 818 SIR BB al xI 3 2 3 2 Cervical Spine Head Cervical Spine Body CSP B 140 2 umbar Spine ESE 140 206 2 140 CTA Thoracic Aorta A CTA Abdominal Aorta AAB 140 CTA Pulmonary Vessels PV 140 Osseous Pelvis OP 140 CSP H 140 A a b N Silo En ak N a do w ES ME ES Aa a os al 3 3 ar 25 ers moe an 5 Los 493 ro 62 120 120 100 170 Effective dose E refers to ICRP 103 Average unweighted 137 1 2141 11 220 o 78 eo re rt 2211 286 284 5152 102 100 119 109 117 All relative and reference values refer to the corresponding average values of the German single slice CT survey conducted in 1999 by DRG and ZVEI Fig 7 5 Worksheet Benchmarking SSCT Standard examinations for which comparative dose calculations Benchmarking can be made area Standard Examination input cells for scan parameters area Scan Parameters and the resulting absolute and relative dose values area Dose Values and Relative Values Relative values refer to the average values of the German CT survey in 1999 Values above average are highlighted in red The
21. INH 37 Fig 7 7 Comparison of actual values of scan length top left pitch factor top right number of scan series bottom left and slice thickness bottom right with average values of the 99 German CT survey ref User s Guide CT Expo V 2 3 Application Module Benchmarking By using the example it is easy to see how to inter pret these values and how to make use of them for the optimisation of scan protocols These values re fer to a realistic example of a hospital which partici pated in the CT survey Please note that the scan pa rameters applied at this hospital are not representa tive for the scanner model concerned The unweighted mean values in the lower line of fig 7 5 show that the overall exposure practice at this particular institution is slightly higher than the aver age For users of modern spiral scanners such as a Somatom Plus 4 this finding indicates a poor result however because the average values of the survey also include contributions from older scanners which are much less dose efficient A closer look at the dose length products shows values significantly higher than the average for the examination types chest CHE 141 pulmonary vessels PV 163 cervical spine CSP 144 and lumbar spine LSP 158 Con trary to this the DLP for the examination type Fa cial Bone Neck FB N 16 is considerably be low average The values of the local dose quantity C
22. T scanners manufactured by Philips applies also for Elscint Marconi and Picker CT Twin Mx Twin Mx8000D Mx8000 Quad Mx8000 ID Teenies BEE Brilliance series Brilliance all Scan parameter Tube current via mAs slice effective I mAs slice t Exposure time per J t scan or rotation 1s Scan Time Rot Time Current time As sli product effective MASISIICe i via Scanmode via h Number of slices N col Single N 1 for CT Twi A h 0 5mm N 2 scanned Dual N 2 simultaneously Fused N 2 else N 4 via Collimation via Slice Thickness Single Dual p 0 7 or 1 5 ia NX Slice collimation at h h 111 via N h via Thickness data acquisition p 1 or 2 first sub menu as for Mx8000D via Collimation h h 13 Fused cot Aec Fused h h 12 z E ol V Table teed per via Pitch Per N Scan Increment as for CT Twin as for CT Twin as for CT Twin Increment scan or rotation TV N h_ p pose relevant Pitch p TV N h as for CT Twin as for CT Twin as for CT Twin p Increment N h pitch factor col i Reconstructed slice thickness FWHM Thickness L Scan length in cm 0 1 Sequence Length 0 1 Length h Single Dual T h 47 User s Guide CT Expo V 2 3 Appendices Tab A 3 MSCT scanners manufactured by Siemens via mAs slice Tube current effective I mAsislice Ite Exposure time per scan Rot time or rotation Current time product mAs slice effective Number of sli
23. TDI are de termined by the settings of tube voltage U kV and current time product Q mAs From fig 7 6 it can be seen that the CTDI for these four types of examina tions is already above average The reason for this is identified as the choice of an increased tube voltage 140 kV which has not been compensated by a re duction of mAs product A comparison of scan length fig 7 7a shows mar ginally higher values for chest and lumbar spine ex aminations by 10 to 20 compared to the corre sponding survey values Scan length therefore does not contribute significantly to the above average dose values When pitch factors are compared fig 7 7b it be comes clear that with the exception of Facial Bone Neck the protocols adopted have not been optimised On a spiral scanner while examinations of the brain the cervical spine and the lumbar spine are usually performed in sequential mode with pitch 1 all other types of examinations are normally 38 User s Guide CT Expo V 2 3 Application Module Benchmarking scanned with pitch 1 5 Therefore the integral dose values at that particular institution are increased by that factor for most examinations The comparison of the number of scan series fig 7 7c however exhibits reduced values with the ex ception of liver kidneys scans The adoption of sin gle series protocols compensates for the effect of other dose increasing influences to some extent
24. User s Guide CT Expo V 2 3 CI Expo V 2 3 A Tool for Dose Evaluation in Computed Tomography User s Guide April 2014 User s Guide CT Expo V 2 3 Impressum Authors adresses Dr rer nat G Stamm c o Medizinische Hochschule Hannover Abt Experimentelle Radiologie D 30623 Hannover e mail stamm georg mh hannover de Dr rer nat H D Nagel c o SASCRAD Fritz Reuter Weg 5f D 21244 Buchholz e mail drhdnagelOsascrad com Insofar as this publication mentions any dosage or application readers may rest assured that the authors editors and publishers have made every effort to ensure that such references are strictly in accordance with the state of knowledge at the time or production of this publication Nevertheless every user is requested to carefully examine the manufacturer s leaflets accompanying each drug or piece of equipment on its own responsibility whether the dosage schedules or protocol settings recommended therein or the contraindications stated by the manufacturers differ from the statements made in the present publication Such examination is particularly important with drugs pieces of equipment or protocol settings that are either rarely used or have been newly released on the market Trade mark protection will not always be marked The absence of a reference does not indicate an unprotected trade mark All rights reserved No part of this publication may be reproduced stored in a retrieval s
25. a a 20 Step 1 Selection of Examination Type 21 Step 2 Selection of Scanner Model 0 cc ccc esses seeeeneees 21 Step 3 Input of SPR Parameters snesesennenenesnenenenesnnnennnn 22 Step 4 Input of Scan Parameters ccecceseeeteeteeseteeseeeceeeneeseeees 22 Step 32 Results nassen ae aan 23 Step 6 Effective Dose Calculation Mode u ee 25 Comparison with Survey Results uessssessnesnesnennennennennenn 25 RESET ee NO 26 6 Application Module Light sueina iisen 27 Application Areas ii nenn 27 Input Steps nennen anne 27 Step 1 Selection of Examination Type 27 Step2 Input of CTDIvol and DLP scssssssssssesssesssseesesseesens 28 Step 3 Correction for dose modulation effects 0 0 eee 29 Step A RESUS u a asked 29 RESO ii siicssscscssessssstsssssssssassaveascascascesenastocticesetoetoescaveascoseeseevestes ves 30 7 Application Module Benchmarking 31 Application Areas u a 31 Selection of the Appropriate Worksheet 31 Benchmarking of SSCT Scanners 32 Step 1 Selection of Scanner Model ueennsessenneneneennennne 32 Step 2 Effective Dose Calculation Mode uneeeene 33 Step 3 Selection of Examination Type Step 4 Input of Scan Parameters 00 0 eects conan cin ra nanino 33 Res iii ir ieeetiastalasseubavied ded Aids for Interpretation and Optimisation 3 Benchmarking of MSCT Scanners e
26. andard CT examinations of adults As the limits of the body section to be scanned are al ready defined the selection of the lower and the up per limits of the scan range as in Calculate mod ule is not required Assessment of the dose contri bution resulting from scan projection radiographs Topogram Scout Surview Pilot Scan etc is an other feature offered in this module This module should be used in daily practice to calculate and document the dose of each CT examination performed e for those examinations where the same body sec tion or parts of it is scanned more than once and with different scan parameter settings e if a direct comparison with the corresponding val ues of the German survey on CT exposure prac tice in 1999 is desired With the advantage of a faster data input comes a compromise of accuracy whenever the actual length of the scan range differs from the pre defined length Although the pre defined length can be corrected by manually entering the actual length the mean con version coefficient is not changed accordingly How ever this is of importance only for the calculation of effective dose The error resulting from this simpli fication is normally small and can be tolerated in most cases Input Steps In this section the procedure to enter the data re quired for dose calculations is described step by step As many details are identical with the procedure in the Calculate m
27. been installed is used by you personally for at least 80 of the time You are not authorised a to use the software as a part of an other commercial product without having the written permission of the manufacturer b to copy the documents accompanying the software iii User s Guide CT Expo V 2 3 License Conditions c to loan or to rent the software or to assign sub licenses d to re develop reverse engineering to decompose to disas semble the software or to attempt in other ways to gain access to the source code of the software to alter the software to trans late it or to generate products which have been deduced from this software Limited guarantee The manufacturer of this software guarantees for a period of sixty 60 days after delivery data that the medium on which the software has been distributed is free from faults If the prod uct purchased by you should not meet this guarantee the manu facturer is free either to replace the copy of this software or to refund the fee paid for the software In both cases a proof of the purchase of the software must be sent to the manufacturer Updates The manufacturer of the software makes every endeavor to pro vide regular updates of the scanner database contained in the software that can be ordered by interested license holders for a moderate fee Updates are exclusively announced via e mail and require personal registration of the license holder Disclaimer o
28. ces via Slice collimation scanned simultaneously N ho Slice collimation at data via Slice collimation acquisition N ho ta Table feed per scan or rotation Dose relevant via N h and TF pitch factor p TF N ha Reconstructed slice FPES ET thickness FWHM SI Ma Scan length in cm L 0 1 Scan range Note On Sensation 64 total collimation N h in z sharp mode is always 32 0 6 mm not 64 0 6 mm as erroneously stated at the scanner s console Make therefore calculations with N 32 independently acquired slices TF Feed rotation 53 Tab A 4 MSCT scanners manufactured by Toshiba Tube current electrical Exposure time per scan Scan time or rotation Current time product a t electrical R Number of slices column Thickness scanned simultaneously value in brackets h a Table feed per scan or 2nd level Continous rotation or Range table Dose relevant 2nd level Continous pitch factor or Range table Reconstructed slice Image Thickness 2nd thickness nominal level Recon Detail Scan length in cm L 0 1 Range h Slice collimation at data Thickness acquisition Note Make input of mAs for Toshiba s multi slice scanners always separately with electrical tube current I and exposure time t never with effective mAs as also indicated on some consoles 48 User s Guide CT Expo V 2 3 Appendices Appendix B
29. curate dose estimates are always achieved by using the latest ver sion of CT Expo Overbeaming Effects In case of multi slice scanners and single slice scan ners from Elscint and Toshiba the width of the beam in z direction is larger than the portion used for de tection for all collimator settings The parameters that are needed to correct for this effect overbeaming correction are included in the scanner data 51 User s Guide CT Expo V 2 3 Appendices On some single slice scanners post patient colli mation is used on scans where the slice thickness is below 2 mm In this case the dose profile resulting from the primary collimation close to the x ray source is wider than the slice profile at the secondary colli mation close to the detector array e g 2mm vs Imm This overbeaming effect is also corrected Scan Projection Radiograph SPR As demonstrated by calculations that can be made in module Standard the dose contribution from the SPR Scanogram Topogram Scout View etc is relatively small Normally it accounts for only 1 2 of the effective dose of the CT examination and can therefore be neglected Larger contributions 10 20 of total dose may occur in examinations which are characterised by low dose settings e g sinuses low dose chest paediatric examaminations or a short scan range e g bone mineral density studies and pae diatric examinations in particu
30. d in the assess ment of organ doses resulting in larger discrepan cies In order to allow for the correction of dose modulation effects a typical mAs profile has been evaluated fig D1 which is based on measured attenuation data of adult standard patients The conversion into relative mAs values follows the modulation characteristic of the present CareDose 4D automatic dose control system This employs a gentle adaptation of mAs to differences in effective body diameter mAs x 2 per 8cm in the trunk per 20cm in the head neck range and per 30 cm in the leg s range It should be noted that the actual profile depends to a large degree on the modulation strength of the scanner on the individual attenuation charecteristics of the patient and on other factors such as upper and lower mAs limits As an example the mAs adaption to differences in body diameter is much stronger 55 User s Guide CT Expo V 2 3 Appendices mAs x 2 per 4 cm if automatic dose control systems with constant noise characteristic GE Hitachi Toshiba are used At the same time the mAs range is restricted in these systems by applying upper and lower limits factor 2 to 3 Nevertheless the mAs profiles shown in fig D1 allow to account for the effects of longitudinal and 3D dose modulation in adult patients in an approximate manner For these reasons however a similar correction for pure angular dose modulation is not possible The averag
31. domen pelvis and osseous pelvis examinations If in those cases the calcula tion of uterine dose is required this can easily be made in application module Calculate by using the same scan parameters Note The integral dose values of the complete examina The uterine dose exceeds the first stage 20 tion are the sum of the values of each scan series and Dose Values per Scan or per Series CTDI CTD DLP Effective Dose E mGy m6y mGy cm msy m f m Istopr 008 oos 5 5 008 0 10 2nd SPR 0 08 oos 5 5 008 0 10 istsenes 125 87 102 192 32 at 2nd Series 156 114 238 238 40 51 3rd Series 208 148 658 628 111 134 CTDI and DLP values refer to 32cm body phantom Effective dose E refers to ICRP 60 6 Effective Dose Dose Values per Examination ICRP 60 DLP Effective Dose E mGy cm msy C 103 m t m 1097 1067 185 228 Effective dose E refers to ICRP 60 Fig 5 6 Results of the dose calculations for each particular SPR and scan series and the complete examination Integral dose values dose length product DLP and effective dose E are listed for both male m and female f standard patients ADAM and EVA respectively Activate the corresponding button to select the organ weighting scheme for effective dose calculation 24 User s Guide CT Expo V 2 3 Application Module Standard SPR and are presented se
32. e quantities are therefore independent of patient dimen sions with the exception of body region and age group A direct dependence on patient size is intro duced however if CTDI is used to determine organ dose Organ dose is dependant on many variables such as variability of organ position and dimension and is subject to large error Conversion Factors Calculation of organ dose and effective dose inevita bly depends on the accuracy of the conversion fac tors used These factors are based on the modelling of mathematical phantoms The statistical error of the Monte Carlo simulation involved amounts to a few percentage points and can be neglected The prin cipal sources are 1 systematic errors which result from the definition of these phantoms and ii the geometrical position of the organs inside Depend ing on the set of conversion factors used organ and effective dose values calculated with different pro grams may differ to some degree The general agree ment between the data set used in CT Expo Zankl 1991 and the NRPB data set Shrimpton 1991 which is frequently be used by others is good This holds however for only one scanner model with Tab D 1 Specifications of the mathematical phantoms on which the conversion factors used for the assessment of organ and effective dose values are based Zankl 1991 Zankl 1993 Phantomtyp ADAM EVA CHILD BABY Alter gt 18 J gt 18 J 73 6 Wo Gr e cm 170 160 115
33. e values of mAs or CTDI of the corre sponding scan series have to be used as input param eter If these values are neither available at the scan ner s console nor in the dose report of the examina tion or if the display shows the peak instead of the average value as currently applied by Toshiba scan ners the required average values must be determined from the individual values of all images in the scan series Effective Dose Calculation The calculation of effective dose in modules Calculate and Standard is performed separately for each gender For males the contribution of breast dose is not taken into account as the associated radiation risk is negligible due to the small size of the organ compared to the female breast In module Benchmarking however the gender in dependent calculation is performed according to the formula defined in ICRP 74 ICRP97 E zz Woreast gt Ha T E sE Sl Xw T breast This holds for both calculation modes ICRP 60 and 103 As the contribution of the breast is effectively doubled effective doses for all types of examination that include the breast region in particular heart and chest are higher than the average of effective doses separataly assessed for ADAM and EVA 56 User s Guide CT Expo V 2 3 Appendices Total Error When using CT Expo the typical total error in dose calculation is e 10 to 15 for those quantities which can al
34. emens hd Somatom Plus 4 Serics y Fig 7 2 Selection of scanner model manufacturer and type of scanner Scanner Data for Somatom Plus 4 Series Head Neck CTD CTD N he 10 0 mm Pu 0 82 Po dz dz 10 10 mm ker 1 00 ker Pr 00 kw Une 120 Ur Mor Dor 20 1 0 Fig 7 3 Scanner data for the selected scanner divided into data for the head neck and body region 32 User s Guide CT Expo V 2 3 Application Module Benchmarking Step 2 Effective Dose Calculation Mode The calculation of effective dose can be performed either according to the previous method ICRP 60 ICRP 1991 or the new method ICRP 103 ICRP 2008 by activating the corresponding button fig 7 4 ICRP 60 C 103 Fig 7 4 Selection of calculation mode for effective dose 2 Effective Dose Step 3 Selection of Examination Type A selection of the scan range is not necessary as this is made implicitly by entering the required data into the corresponding line fig 7 5 The 14 examina tion types are identical to those already known from the Standard module Only the input of the actual scan length is requested The scanner data and con version coefficients required to perform the dose cal culations in the pre programmed cells are retrieved automatically Step 4 Input of Scan Parameters The input of the scan and examination parameters is made in a similar way to that in
35. ent MSCT prac tice still requires major optimisation effort Brix 2003 Contrary to the graphical presentation of relative dose values used for SSCT scanners the pitch corrected volume CTDI CTDI is used instead of the weighted CTDI fig 7 10 for the following reasons the majority of MSCT scanners makes use of a spe cial kind of z interpolation z filtering which ensures that effective slice thickness image noise and aver age local dose inside the scan range are independent from the pitch selected Nagel 2002 Therefore the volume CTDI is the relevant descriptor of local dose for MSCT scanners Volume CTDI is identical to the CTDI value displayed at the scanner s console The additional figures provided for the comparison of scan parameter settings are also identical to those used for SSCT scanner with the exception of slice thickness With MSCT scanners the slice thickness used for data acquisition usually differs from the slice thickness used for image presentation The noise impression however depends only on the latter Po tential consequences for the selection of mAs set tings therefore result from h not from h There fore the comparison of slice thickness is made for h o fig 7 11 Slice Thickness h mm w ad oO SY m ras Fig 7 11 Comparison of actual slice thicknesses recon structed slice thickness h with average values of the 99 German CT surve
36. examinations are presented in a graphical form The presentation is restricted to weighted CTDI CTDI and dose length product DLP which serve as the main descriptors of local and integral dose and in which diagnostic reference levels for CT have been established Four additional figures allow for identification of those scan parameters which significantly differ from common practice and which may give rise for dose levels above average These figures give comparisons of the actual values act and the corresponding average values from the CT survey ref for the following scan parameters Scan length L fig 7 7a pitch factor p fig 7 7b number of scan series fig 7 7c and slice thickness h fig 7 7d 35 User s Guide CT Expo V 2 3 Application Module Benchmarking OCTDiw mDLPw v w o a v 8 o BRN FBISIN FB N H FB N B CHE ABD PE PEL LIKI TRUNK ATH OP CSP H CSP B LSP Average Standard Examinations Fig 7 6 Relative dose values for each type of examination in terms of weighted CTDI CTDI and dose length product DLP Bars exceeding the 100 line represent dose values above the average of the 99 German CT survey 36 Application Module Benchmarking User s Guide CT Expo V 2 3 Dact Mref Dact Mref Td ad day 3H QN a4 HN G4 NIS 84 naa 5 5 a a E o D Td 34087 3H Q N a4 my cas HN 4 nisvad Naa as 1 pe ueg Salias JO J3QU
37. f liability In no condition will the manufacturer of the software be liable to you for any consequential incidental or indirect damages including damages for loss of business profit business inter ruption loss of business information and the like arising out of the use or inability to use the software even if the manufac turer has been advised of the possibility of such damages iv User s Guide CT Expo V 2 3 Preface Preface After more thanl0 years CT Expo has meanwhile become the world wide only software that allows for dose calculation for practically all CT scanners and is regularly updated Besides the addition of new scanner models a number of improvements have been introduced over the years that have increased the ac curacy of dose assessment and have extended the functionality of this tool The 12th version with the new update V 2 3 now comes with another significant innovation assess ment of the dose contribution resulting from the scan projection radiograph This is rarely known and of ten grossly over estimated Now it is possible to quan tify that its contribution is almost negligible in the majority of cases In addition a number of other modifications have been introduced in V2 3 These are documented in the file Release_Notes v2 3 E pdf and can be found in the CT Expo V 2 3 folder As before CT Expo will be availabe as shareware at a price which we anticipate will make it easily affo
38. fmsan ImSvimGy cm females males females ICRP6O ICRP 103 without dose modulation with dose modulation males Fig 5 1 Selection of examination type with the corresponding scan length scan range limits and mean conversion coefficients 21 User s Guide CT Expo V 2 3 Application Module Standard the overranging correction These values are used to calculate the Ks factors for the selected collimation and tube load and AL for the selected collimation and pitch factor Step 3 Input of SPR Parameters The following parameters are required to calculate the dose contribution resulting from the scan projec Scanner Data for Scan Region Body SID Une Pen Ker dz dzz N hur Mor Bor mGuyim s k mm mm mm ooss 120 os 1 1o 1o to 20 10 Fig 5 3 Scanner data with the corresponding parameters used for dose calculations and corrections 3 Scan Projection Radiograph Parameters 1st SPR 2nd SPR tion radiograph SPR fig 5 4 tube voltage U in kV tube current I in mA table speed TS in mm s beam width N h in mm and SPR length L in cm Alternatively to tube current and table speed the SPR s total mAs Q p can be used If table speed and beam width are not known 100 mm s and 3 mm can be applied as typical values instead Enter the parameters separately if two SPRs are acquired for the pertaining examination Step 4 Input
39. g the button Body mode for head neck region fig 4 7 In this case body CTDI data are used regardless of the location of the scan range Furthermore the check box Spiral mode must be activated for examinations performed in spiral scanning mode This allows to take the extra rotations needed for data interpolation at start and end of the scan into account when calculating dose length product and effective dose The extent of this over ranging is displayed in the cell AL 4 x Select mode 7 Body mode for head neck region M Spiral mode For examinations performed with longitudinal or 3D dose modulation the resulting effects on local dose distribution can be taken into accountby activating the corresponding check box The relative mAs characteristic shown in the appendix fig D 1 is used in the assessment of organ and effective doses This function is applicable for adult patients only Note In order to calculate DLP and effective dose for routine brain examinations overranging is taken into account according to the exposed part of the body If for example the imaged region starts at the vertex only half of the overranging is dose relevant Longitudinal 2 axis dose modulation adults only Fig 4 7 Selection of the basic scanner data applicable to the body mode for examinations in the head neck region carried out in body scanning mode of spiral scanning mode and of correction for the effects of long
40. he security centre settings Note Program versions obtained from original diskettes CDs with serial number or from updates distributed by the manufacturer via e mail attachments have been checked for viruses before shipment These versions can be opened and activated without hesitation No guarantee can be given however for program versions that have been obtained by other non author ised channels After having given your OK to another box which contains important information the start sheet fig 2 1 is accessible From this the different applica tion modules Calculation Standard Light and Benchmarking and a help sheet Help can be selected The application may also be terminated in a conventional way End CT Expo v2 3 7 Calculation Calculate Benchmarking Standard Help Light Close y Copyright All rights reserved Copyright by Georg Stamm and Hans Dieter Nagel Hannover Buchholz 2001 2014 Fig 2 1 Start sheet with selection of application modules User s Guide CT Expo V 2 3 Start Sheet As all input operations performed by the user are in terpreted by MS Excel as a change you will be asked when terminating CT Expo V 2 3 whether you wish to store the changes made or not Normally your de cision should be NO In particular situations how ever it may be desirable to store the latest inputs
41. ic Aspects NRPB 249 London HMSO 1991 48 Shrimpton 2000 Shrimpton PC and Wall B Reference doses for paediatric computed tomography Radiation Protection Dosimetry 2000 90 249 252 Stamm 2002 Stamm G Nagel HD CT Expo ein neuarti ges Programm zur Dosisevaluierung in der CT Fortschr Rontgenstr 2002 174 1570 1576 Zankl 1991 Zankl 1993 Zankl M Panzer W and Drexler G The Calcula tion of Dose from External Photon Exposures Using Reference Human Phantoms and Monte Carlo Methods Part VI Organ Doses from Com puted Tomographic Examinations GSF Bericht 30 91 OberschleiBheim GSF Forschungszen trum 1991 Zankl M Panzer W and Drexler G Tomographic Anthropomorphic Models Part II Organ Doses from Computed Tomographic Examinations in Paediatric Radiology GSF Bericht 30 93 Ober schlei heim GSF Forschungszentrum 1993 59
42. ion of the serial number and the origin of the software on the registration form which is attached to the software Mult iple registration of the software under the same serial number leads to the loss of the license its guarantees and privileges The software acquired with this license remains the property of the manufacturer and is protected by national laws international contracts and intellectual property rights In accepting these li cense conditions you have been given the right to use this soft ware Unless additional regulations accompanying this license have been agreed upon the use of this software is bound to the fol lowing conditions You are authorised a to use a copy of this software only on a single computer b to produce a copy of this software for archiving purposes or to copy the software to the hard disk of your computer and to archive the original floppy disk c to use the software in a network environment provided that you have purchased a license for each computer which has ac cess to the software via the network d to permanently transfer the rights on this software to a third party provided that all copies of this software and the accom panying documents are handed over and that the receiver of the software also accepts all parts of this license conditions e to use this software also on a mobile computer or on a single home computer provided that the computer on which the soft ware has initially
43. is made automatically depend ent of the scan range selected A scan range which is predominantly located above the landmark cervical Scanner Model Manufacturer Siemens v Somatom Plus 4 Series y Fig 4 5 Selection of scanner model manufacturer and type of scanner vertebra 7 thoracic vertebra 1 represents the head neck range If the scan range is predominantly lo cated below this landmark the body CTDI values are used The numbers displayed in the fields k and AL are of particular importance for multi slice scanners kog 18 a factor used to correct for the exposed areas outside the detector array overbeaming while AL accounts for the additional scan length in spiral mode overranging Both values are dependent on the selected scan parameters and may change unless the exposure settings have been entered into the corre sponding cells Scanner Data for Scan Region Body fey TE Pen Kor kos AL mGuytmaAs kv em ATA ee EAS ee PI REF TE Fig 4 6 Scanner data used for dedicated dose calculations for the selected scanner User s Guide CT Expo V 2 3 Application Module Calculate Step 4 Adaptation of Scanning Mode CT examinations of the neck region are often carried out in body mode if the shoulder region is included in the scan range The automatic assignment of basic scanner data head neck or body made by CT Expo can be overruled by activatin
44. issisicisisssiiisisssssi isise Step 1 Selection of Scanner Model uueesnsensenneneneennnenene Step 2 Effective Dose Calculation Mode Step 3 Selection of Examination Type Step 4 Input of Scan Parameters Results 42 Printing the RESUS access nennen 45 RESET cco cz rara tordo oe tabaco 45 Appendices sismos dla 46 Appendix A MSCT Scan Parameter Translator 46 Appendix B Calculation Formulas Appendix C Types of Standard Examinations Appendix D Accuracy of Dose Calculations A a a ASNE oE vii User s Guide CT Expo V 2 3 Introduction 1 Introduction CT Expo V 2 3 is an MS Excel application written in Visual Basic for the calculation of patient dose in CT examinations It is based on computational methods which were used to evaluate the data collected in both German surveys on CT exposure practice in 1999 and 2002 A comprehensive description of these methods is documented in the book Radiation Ex posure in Computed Tomography Nagel 2002 CT Expo V 2 3 allows the calculation of the follow ing dose quantities e Weighted CTDI e Volume CTDI Effective CTDI e Dose length product e Organ doses e Effective dose according to ICRP 60 and 103 In contrast to similar programs for dose calculations in CT CT Expo V 2 3 offers the user a number of unique features such as e dose calculations for all age groups adults chi
45. itudinal dose modulation User s Guide CT Expo V 2 3 Application Module Calculate Step 5 Input of Scan Parameters Note Any input made in cell Q is automatically The input of the actual scan parameters is made in copied into the adjacent cell Q thereby over the cells kept in white fig 4 8 The following set of riding the product of I and t Enter zero into parameters is required the cell Q to restore the initial state e tube voltage U kV The accuracy of the dose calculations greatly depends e electrical tube current I mA and on the quality of the data input Please carefully en acquisition time per slice or rotation t s ter the scan parameters that are displayed at the op alternatively current time product Q mAs erator s console or the outcome from the way that e total collimation N h mm the CT examination is carried out e g during CT e table feed TF mm fluoroscopy e reconstructed slice thickness h mm number of scan series Ser a Please Enter Actual Settings A a z U t Qu Q N hai TF Prec p Ser kV mA s mAs mAs mm mm 200 mm Fig 4 8 Input cells in white for entering the actual scan parameters To avoid input errors a number of important hints should be observed see text 12 User s Guide CT Expo V 2 3 Application Module Calculate Note Prior to the introduction of multi slice CT there was a standard way of presenting
46. l dren neonates e dose calculations for each gender e dose calculations for all existing scanner models e correction of scanner specific influences e correction of overbeaming effects e correction of overranging effects in spiral mode e free and standardised dose assessment from scan parameters as well as from dose data provided by the scanner e assessment of the dose contribution resulting from scan projection radiographs e comparisons with results from the German CT survey e a comprehensive benchmark function including guidance on dose optimisation User s Guide CT Expo V 2 3 Introduction CT Expo V 2 3 consists of four application modules e Calculation Allows to calculate age and sex spe cific patient dose values with individual selection of the scan range this can be made in a separate sheet Scan Range with graphical input facili ties e Standard Offers dose calculations for pre defined standard CT examinations adults only the se lection of the scan range is made automatically and for both sexes simultaneously For complex types of examinations separate dose calculations may be made for each scan series with different sets of scan parameters Calculated values can be compared with the corresponding average values of the German CT survey using a separate sheet Compare In addition the dose contribution re sulting from scan projection radiographs can be assessed e Light Allows
47. lar if it is not possi ble on your scanner to reduce the length of the SPR SPR dose assessment is primarily made by calcula tion of the resulting CTDI The absorbed energy from a SPR and thus the average dose is the same as from a regular scan with rotating x ray tube ac quired with comparable exposure settings The re sulting organ doses however are different due to the differences in irradiation geometry Therefore no ex plicit statements on organ doses from SPR are given The accuracy of the corresponding effective dose is also restricted As the resulting values are compara bly small this limitation can be tolerated Spiral Scans Spiral scans require additional data at the start and the end of the spiral Only integral dose quantities DLP E are increased by this effect This is taken into account by the overranging correction introduced in V1 4 Patient Influence All dose calculations strictly apply only for standard 52 User s Guide CT Expo V 2 3 Appendices patients that are represented by the mathematical phantoms ADAM EVA CHILD and BABY The most important specifications of these phantoms are listed in tab D 1 Different patient dimensions only impact on the cal culation of effective dose Weighted CTDI and dose length product however refer to standardised cylin drical phantoms made from PMMA of diameter 16 and 32 cm Head and Body respectively Thes
48. lection of application module Benchmarking e Save Print Storing or printing the content of a sheet e Reset Resetting all input cells e Help Selection of short instruction in sheet Help Touching the left edge can change the location of the navigation toolbar By clicking on the Close button the bar can completely be removed from the sheet To re install the toolbar when it is not available click on VIEW TOOLBARS NAVIGATION from the standard Excel menu In Excel version 2007simply click on Add Ins Zoom in a Zoom out tat Goto Start Calculate Scan Range E Standard a Comparison E Light Benchmark Save Print Reset Help Fig 3 1 Navigation toolbar User s Guide CT Expo V 2 3 Application Module Calculate 4 Application Module Calculate Application Areas The Calculate module allows dedicated dose cal culations for all groups of age and sex This module should be used whenever e dose calculations are required for those types of examinations which differ significantly from the pre defined standard CT examinations covered in module Standard an individual selection of the scan range is made e the calculation of uterine dose is necessary e paediatric CT examinations are carried out Although it may be an advantage to more accurately determine dose using a free selection of scan range it requires an extra effort to do so Input Steps In
49. m body phantom Effective dose E refers to ICRP 60 Series y 4 Average Values per Fig 5 7 Results of the dose calculations for each particular scan series from the actual examination as in fig 5 6 and average values per scan series from the German CT survey in 1999 Galanski 2001 23 User s Guide CT Expo V 2 3 Application Module Standard and indicate that the calculated dose value for this examination was higher than the corresponding av erage value from the German survey Comparisons of this kind can be made for the entire set of standard examinations in the Benchmarking module There you will find detailed information which may be helpful in identifying those param eters which differ significantly from usual practice and which are responsible for increased dose values Reset By clicking on the area Rese in the navigation tool bar all data entered in the white cells are erased im mediately The dose values in the yellow cells also disappear If you need to erase only a small amount of data first highlight the corresponding cells then push the Erase key on the keyboard of your com puter By clicking on the corresponding areas in the navi gation toolbar you can return to the start sheet or to other application modules of your choice Dose Values per Examination Results per Examination m Relative Values in DLP mGy cm Effective Dose E mS B m f 109
50. made If you decide to do this the previous version of CT Expo will disappear Note The authors recommend that users make a backup copy before using CT Expo for the first time and that this is made on a separate storage device This will guard against the conse quences of accidental loss or damage or breakdown of the computer system If you should have obtained your CT Expo application on a standard floppy disk or CD copy all files on this device to your hard disk and work only with this copy Carefully store the original storage device in a separate location for emergency situations User s Guide CT Expo V 2 3 Navigation Toolbar 3 Navigation Toolbar An additional means to switch from one sheet to an other is provided by the navigation toolbar shown in fig 3 1 This toolbar is normally located at the upper boarder of the Excel sheet The functions of the dif ferent buttons are e Zoom In Enlarged display e Zoom Out Reduced display e Goto Start Back to start sheet e Calculate Selection of application module Cal culate e Scan Range Selection of sheet Scan Range in order to make graphical input of the scan range e Standard Selection of application module Stand ard e Comparison Switch to sheet Comparison in or der to compare the dose values calculated in Standard to those of the German CT survey e Light Selection of application module Light e Benchmark Se
51. mation on the corresponding values of scan length L and conversion factors which de pend on the choice of patient type and scan range may be obtained The conversion factors are needed in order to calculate effective dose and uterine dose Overriding the content of both input cells from z and to z is possible at any time By clicking on the area Get Values however the actual values which have been set up in the Scan Range sheets are restored Step 3 Selection of Scanner Model The scanner model for which dose calculations shall be performed is defined fig 4 5 by selecting e the scanner manufacturer and e the type of scanner from the corresponding drop down menus When selecting the type of scanner please note care fully that sometimes different versions of a particu User s Guide CT Expo V 2 3 Application Module Calculate lar scanner exist which differ in the dose relevant scanner data In order to distinguish between these versions a special name or the year from which the modification became effective or the characteristic in which this version differs from other scanners of the same type is attributed e g old BS BS beam shaper Information used to perform dedicated dose calcula tions for the selected scanner model can be obtained from the grey cells in the box Scanner Data fig 4 6 Initially the correct choice of the normalised CTDI head or body
52. odule only those items are men 20 User s Guide CT Expo V 2 3 Application Module Standard tioned here which are specific to this module Step 1 Selection of Examination Type Selecting the examination type from the drop down menu shown in fig 5 1 gives the definition of the scan range The values of scan length scan range limits co ordinates and anatomical landmarks and mean conversion coefficients f sa are displayed for information purposes in the corresponding cells As for the subsequent dose calculation this is made for both sexes simultaneously Step 2 Selection of Scanner Model The selection of the scanner model is made in the same way as in the Calculate module fig 5 2 In 1 Standard Examination males Routine abdomen amp pelvis v 0 gt 43 Pubic symphysis Standard Scan Length L cm females from gt to O gt 41 Diaphragm stead of the overbeaming correction factor Kop and AL the extent of overranging the following param eters are displayed in the Scanner Data box fig 5 3 e dzl and dz2 the effective width of the overbeam ing range for regular and very small beam width settings respectively e N h the total collimation applicable to the value of normalised CTDI Scanner Model Siemens v Somatom Plus 4 series v 25 Scanner Selection Manufacturer Scanner Fig 5 2 Selection of scanner model manufacturer and type of scanner
53. one Neck which are far below average may be adjusted upwards to about 65 of the values 39 User s Guide CT Expo V 2 3 Application Module Benchmarking Scan Parameters Dose Values Relative Values U l A ig L ser Spiral CTDI CTDha DLP E CTDI CTDhy DLP E k mA s mAs mAs mm mm mm cm Mode mGy mGy mGy cr mSv in of Survey Average 120 200 15 300 300 10 12 10 4 10 per Examination Example per Scan Facial Bone I sinuses FBISIM 120 160 15 0 gt 3 al rs a4 03 ame aim 10 19 Facial 8 Neck Head FBN H oll D ae a eas coe E Facial Beck Body FENE ie ez e ra ese 25 224 om Routine Chest CHE 120 150 0 75 65 4 9 Routine Abdomen tot ABD PE 165 MIEDO Routine Pelvis L E Ps Liver Kidneys LIKI 120 220 0 7 96 Whole Trunk TRUNK 65 39 105 CTA Thoracic Aorta ATH so 200 CTA Abdominal Aorta AAB 50 CTA Pulmonary Vessels PV Osseous Pelvis Cervical Spine Head CSP H Cervical Spine Body CSPI 201 201 on na osm 65 10 ven Lumbar Spine LSP 3 257 257 193 32 656 67 am 699 Effective dose E refers to ICRP 103 eros weigean mafas 1 we 0 Ysa ro sa ra ee a val ma ows 3 om am oom aon All relative and reference values refer to the corresponding average values of the German single slice CT survey conducted in 1999 by DRG and ZVEI x a 0 s 0 ES e oa B 5 2
54. ork which is easy to use Our experience gained during the evaluation of the German CT survey has led to a tool which has been restricted to only a few essential dose quantities and which focuses on the practicability of the results For us one of the most important goals was to include for the first time the prospect for dose assessment in paediatric CT examinations also This software product is now commercially available at a price which we estimate will be easily afford able for all potential users Please support the shareware idea by paying the nominal fee requested This enables us to continually improve this program and to supply you with regular updates free of charge Hannover Hamburg summer 2001 Dr Georg Stamm Dr Hans Dieter Nagel vi User s Guide CT Expo V 2 3 Table of Contents Table of Contents 1 Introduction ciaci n inicias 1 SS u ae 3 Navigation Toolbar sumisa 4 Application Module Calculate E Application Arcas anciana latas article TNPUE SLEDS irc coro 6 Step 1 Selection of Patient Type 6 Step 2 Selection of Scan Range wel Step 3 Selection of Scanner Model and Step 4 Adaptation of Scanning Mode 11 Step 5 Input of Scan Parameters sossssenissiisssiissiissni nsina 12 e E ON 17 Step 7 Effective Dose Calculation Mode u nee 18 Reset tad it 19 5 Application Module Standard o oo eee eee 20 Application ATC ica 20 A nnan
55. oses H are based on conversion factors for standard patients ADAM EVA CHILD BABY and serve for information pur poses only in particular for organs outside the scan range Step 7 Effective Dose Calculation Mode Fig 4 10 The calculation of effective dose can be performed Organ doses H per scan series left principal organs right either according to the previous method ICRP 60 remainder organs ICRP 1991 or the new method ICRP 103 ICRP 2008 by activating the corresponding button Fig 4 11 Selection of calculation mode for effective dose 18 User s Guide CT Expo V 2 3 Application Module Calculate Reset By clicking on the area Rese in the navigation tool bar all data entered in the white cells are erased im mediately The dose values in the yellow cells also disappear However as these cells are protected the algorithms programmed in these cells simply become invisible If you need to erase only a small amount of data first highlight the corresponding cells then push the Erase key on the keyboard of your com puter By clicking on the corresponding areas in the navi gation toolbar you can return to the start sheet or to other application modules of your choice 19 User s Guide CT Expo V 2 3 Application Module Standard 5 Application Module Standard Application Areas The Standard module offers dose calculations for pre defined st
56. our computer By clicking on the corresponding areas in the navi gation toolbar you can return to the start sheet or to other application modules of your choice 45 User s Guide CT Expo V 2 3 Appendices Appendices Appendix A MSCT Scan Parameter Translator Tab A 1 MSCT scanners manufactured by General Electric I electrical tube current t exposure time per scan or rotation Rotationtime in s Sean parameter Sas eS A O IEEE Current time via and t product electrical Q l t ae ee implicitly Number of slices no explicit info implicitly no explicit info ee no explicit info 1i N 1 scanned normally max possible 1i N 1 normally max possible 2i N 2 normally max possible 2i simultaneously number of slices N 2 2i N 2 number of slices N 4 4i N 4 number of slices N 8 4i 8i Slice thickness Ta TV N p In submenu of Thick Speed data acquisition TV N p Detector Configuration In submenu of Thick Speed Detector Configuration Table feed per as for as for as for i icin al oo uber Scan Mode via Scan Mode UQ p 0 625 ao HQ p 0 75 ee as for NX i ead UM p 0 875 A 3rd value in Thick Speed pitch factor HS p 1 5 p UF p 1 35 US p 1 675 oe eke romina nn uch ha ae ee s length via StartLocation and EndLocation in mm can Ceng sean ent onom cm L 0 1 EndLocation StartLocation 46 User s Guide CT Expo V 2 3 Appendices Tab A 2 MSC
57. parately for both sexes Step 6 Effective Dose Calculation Mode The calculation of effective dose can be performed either according to the previous method ICRP 60 ICRP 1991 or the new method ICRP 103 ICRP 2008 by activating the corresponding button Comparison with Survey Results By clicking on the area Comparison in the naviga tion toolbar you will arrive on a sheet of the same name Here you will find once again the dose values for each scan series as in fig 5 6 In the cells below the average values are listed taken from the German survey on CT exposure practice in 1999 Galanski 2001 for the corresponding type of examination fig 5 7 These values apply per scan series In the outmost right cell of this line the user will find the average number of scan series according to the survey By multiplying the values in this line by this number reference values per examination can be gen erated which may be used for comparison The re sults of this comparison are given as relative values in below the dose values per examination fig 5 8 Relative values exceeding 100 are marked red Dose Values per Scan or per Series 1 Results per Scan Series CTDI CTDi DLP Effective Dose E ImGy Imey msv m 1st Series 2nd Series 3rd Series f m f 125 87 182 102 32 at 156 111 288 238 40 51 208 148 658 628 111 134 CTDI and DLP values refer to 32c
58. perience significant errors may occur with the input of the following parameters e Tube current I Must not be mixed up with the current time product Q if your scanner only dis plays the mAs product please enter this value into the corresponding cell Note For tube current I or current time product Q enter the values as displayed at the operator s 13 User s Guide CT Expo V 2 3 Application Module Calculate console or on the film For scanners which employ pitch corrected values effective mAs mAs per slice these values are auto matically converted into electrical mAs as dis played in the cell Q Note Many scanners now provide a modulation of the tube current along the z axis according to the local attenuation properties of the patient longitudinal dose modulation Use the aver age mAs value for the scanned range and cor rect for local variations by activationg the cor responding check box in step 4 If the average mAs value is not available you may use the dose length product displayed at the operator s console by trial and error vary the mAs prod uct until the DLP value calculated with CT Expo is the same as at the console Note For cardiac CT applications performed with retrospective gating many scanners now offer the possibility for temporal modulation of the tube current controlled by the patient s ECG signal ECG gating Please contact the manu facturer to
59. r organs at the border or outsicde the standard scan range will significantly be affected If the required scan protocol data are available the dose assessment should preferentially be performed in application module Calculate The calculated dose values are given for each gender separately The underlying conversion factors k factors are in accordance with the conversion factors for the mathematical phantoms ADAM and EVA used in CT Expo Compared to the currently used k factors from AAPM report 96 larger differences may be observed for the following reasons e differences in the modelling of the underlying mathematical phantoms e body regions only coarsely defined e k factors for neck scans apply to head mode only missing differentiation between males and females e valid for effective dose according to ICRP 60 only Own comparisons with published alderson phantom based studies and other CT dose calculation programs have revealed that the k factors used in CT Expo give realistic doses for standard sized patients Hence effective doses using the AAPM k factors tend to be too low Reset By clicking on the area Reser in the navigation tool bar all data entered in the white cells are erased im mediately The dose values in the yellow cells also disappear By clicking on the corresponding areas in the navi gation toolbar you can return to the start sheet or to other application modules of your choice 3
60. ral Runoff Cervical Spine Disk Cervical Spine Fracture Lumbar Spine Disk Lumbar Spine Fracture Osseous Pelvis Osseous Pelvis w Testes Head Trunk Head Trunk w Testes Whole Body Abbr BRN SKB FB SIN DENT FB N CHE CHE CHE ABD PE ABD PE LIKI PEL PEL TRUNK TRUNK CAR AOR ATH AAB PV Anatomical Landmarks caudal Skull base Skull base Occlusial plane Inferior margin of teeth Inferior margin of thyroid gland Sinus Inferior margin of adrenals Inferior extremity of kidney Pubic symphysis Inferior extremity of testes Inferior extremity of kidney Pubic symphysis Inferior extremity of testes Pubic symphysis Inferior extremity of testes Aortic arch Superior end of sacrum T12 Superior end of sacrum T10 Sinus Sinus Feet c5 C7 L5 S1 L5 S1 Ischial tuberosity Inferior extremity of testes Pubic symphysis Inferior extremity of testes Feet cranial Vertex Skull base Superior margin of frontal sinus Superior margin of teeth Superior margin of frontal sinus c7 T1 c7 T1 c7 T1 Diaphragm Diaphragm Diaphragm Inferior extremity of kidney Inferior extremity of kidney c7 T1 c7 T1 Vertex Ti Ti T12 T2 3 T8 T5 6 lliac crest c3 ct L3 4 11 1112 lliac crest lliac crest Vertex Vertex Vertex Scan Range male from 82 80 78 76 70 41 36 25 0 5 to 94 92 89 80 88 69 69 69 43 43 43 25 25 68 68 94
61. range in the cells from z and to z fig 4 2 The corresponding values are defined by the first and the last slice position as indicated on the images and on most scanner consoles This input method should only be applied by experienced users who are familiar with the design of the mathematical phantoms ADAM EVA CHILD and BABY and the location of the individual organs inside these phantoms Zankl 1991 Zankl 1993 For less experienced users a graphical input facility 1s provided This facility is accessible by clicking on the area Scan Range in the navigation toolbar De pending on the age group selected in step 1 you will enter either the sheet Adult or Child Baby The limits of the scan range are selected by using the arrow symbols located at the upper border of this sheet and are displayed by the semi transparent red area located over the phantom of choice The fol lowing rules apply e By using the left group of arrow symbols the en User s Guide CT Expo V 2 3 Application Module Calculate tire scan range is displaced up or downwards by the corresponding distance in cm e by using the right group of arrow symbols the entire scan range is lengthened or shortened by the corresponding value in cm When selecting the scan range you should proceed in such a way that initially the lower limit of the scan range Start z is defined by using the left g
62. rdable for all potential users Please support the shareware idea by paying the nominal fee requested This enables us to continually improve this program We will also make every endeavor to provide regu lar updates of the scanner database contained in the software Due to the increased efforts that are neces sary for the preparation of the dose relevant data of new scanners it was no longer possible to distribute updates for free They can however be ordered by interested license holders for a moderate fee Updates are exclusively announced via e mail and require per sonal registration of the license holder Hannover Buchholz April 2014 Dr Georg Stamm Dr Hans Dieter Nagel User s Guide CT Expo V 2 3 Preface Preface First Edition In the past few years increasing efforts have been initiated to significantly reduce the radiation expo sure of CT examinations In Germany a nation wide survey of CT exposure practice was conducted in 1999 as a joint effort of the German Roentgen Soci ety DRG and the manufacturer s association of electromedical equipment ZVEI with a participa tion rate of 50 of all CT users This broad interest has encouraged us to develop CT Expo V 1 0 a tool for CT dose evaluation We hope that every person involved in the production appli cation and inspection of CT scanners who has a role in dose evaluation wants to use it It also provides a powerful tool for users in their daily w
63. roup of arrow symbols Subsequently the upper border of the semi transparent area is shifted to the desired position by using the right group of arrow symbols thus defining the upper limit of the scan range End z All changes can be made either in large or small steps of 5 and 1 cm respectively When setting the scan range limits the following aids for orientation are available e The location of the principal organs inside the phantoms fig 4 4 e the z co ordinates displayed in the cells Start and End and ta dd ho Fig 4 3 Selection of the scan range limits by using the arrow symbols up and down The left group is used to define the lower limit the right group to define the upper limit The resulting scan range is indicated by the semi transparent red area User s Guide CT Expo V 2 3 Application Module Calculate Female breast Lung Liver Bladder Ovaries Testes Uterus Pelvis Fig 4 4 Symbols which represent the principal organs inside the phantoms e the anatomical landmarks given below these cells After having defined the scan range you have to re turn to the module Calculate by clicking on the corresponding field in the navigation bar In the scan range input area shown in fig 4 2 both z co ordi nates from z and to z which have been graphi cally selected earlier are now displayed From the grey cells infor
64. s D terus H mSv Organ dose per scan series In addition the values of dose length product effec tive dose and uterine dose for complete examinations eventually comprising more than one scan series are stated too These are the dose estimates for the en tire examination and therefore are the only relevant values when considering radiation risk Note In CT Expo the calculation of weighted and volume CTDI for paediatric CT examinations is always based in agreement with other au thors such as Shrimpton 2000 on the smaller head phantom which is 16 cm in diameter The resulting dose values CTDI CTDI and Dose Values per Scan or per Series CTDi CTDi DLP mGy mc _ImGyem E De mSv mSv 166 116 485 107 148 Child Baby all CTDI and DLP values refer to 16cm head phantom Effective dose E refers to ICRP 60 Effective dose E refers to ICRP 60 Fig 4 9 Presentation of the calculated dose values per scan or per scan series DLP E D In addition dose values for uterus the complete examination which may comprise more than one scan series are stated for DLP EandD too uterus 17 User s Guide CT Expo V 2 3 Application Module Calculate DLP are usually higher than the values dis played at the console of newer scanners which refer to CTDI if the examination has been carried out in body mode regardless of actual patient size Note All organ d
65. scan parameters of a participant of the survey have been used for this example Note that these are not representative for the participant s type of scanner 34 User s Guide CT Expo V 2 3 Application Module Benchmarking Results The results of the dose calculations are listed in ab solute terms for the most important dose quantities weighted CTDI CTDI volume CTDI CTDI dose length product DLP and effective dose E in the area Dose Values fig 7 5 For the local dose quantities CTDI CTDI these values are per scan slice or rotation both the integral dose quantities DLP E are values for complete examinations av eraged over both sexes In the area Relative Values right of this the value given is the ratio of the dose value for that particular institution relative to that of the German CT survey and given in terms of a The meaning of these val ues is identical to that in the Comparison sheet ie values greater than the average of the German sur vey are indicated red In the lower line of this table the unweighted mean values of all input parameters and results are listed averaged over all types of examinations The relative values given here can be used as a first indication of the dose levels resulting from the exposure practice at the corresponding scanner Aids for Interpretation and Optimisation In fig 7 6 the relative dose values from all types of standard
66. so be measured CTDI CTDI DEP and e 20 to 30 for those quantities which can only be derived by using conversion coefficients or gan dose and effective dose Even larger errors may occur in case of incorrect data input e organ dose assessment for organs located at the boarder or outside of the scan range organ dose assessment when angular and or lon gitudinal dose modulation is applied e unusually large equipment tolerances e unknown or unauthorised scanner modifications 57 User s Guide CT Expo V 2 3 Literature Literature Brix 2003 Brix 2004 Brix G Nagel HD Stamm G et al Radiation exposure in multi slice versus single slice spiral CT Results of a nationwide survey Eur Radiol 2003 13 1979 1991 Brix G Lechel U Veit R et al Assessment of a theoretical formalism for dose estimation in CT Eur Radiol 2004 14 1274 1285 DGMP 2002 Deutsche Gesellschaft fiir Medizinische Physik e V und Deutsche R ntgengesellschaft Pr na tale Strahlenexposition aus medizinischer Indi kation Dosisermittlung Folgerung fiir Arzt und Schwangere Uberarbeitete und erg nzte Neuauf lage 2002 DGMP Report No 7 2002 ISBN 3 92518 74 2 see also http www dgmp de Galanski 2001 Galanski M Nagel HD Stamm G CT Exposi tionspraxis in der Bundesrepublik Deutschland Ergebnisse einer bundesweiten Umfrage im Jahre 1999 Fortschr R ntgenstr 2001 173 R1 R66 ICRP 1991
67. t agent 2 series not the number of slices A series is defined here as the 13 User s Guide CT Expo V 2 3 Application Module Calculate number of times which the same body section or a part of it is scanned Scanning a section in mul tiple steps e g chest upper abdomen pelvis or multiple segments of the lumbar spine is counted as 1 series If the body section is only partially scanned in one of the series e g unenhanced scan of the upper abdomen only contrast scan of the entire abdomen please enter a value between 1 and 2 which takes into account the different lengths of both scans In case of standard CT examina tions the user is referred to the application mod ule Standard which allows the user to perform calculations for up to three scan series with differ ent parameter settings simultaneously Note Please enter here the number of rotations if sta tionary procedures are performed e g CT fluoroscopy or CT perfusion 16 User s Guide CT Expo V 2 3 Application Module Calculate Step 6 Results Results for the following dose quantities are displayed in the yellow shaded cells fig 4 9 e CTDI mGy Weighted CTDI per scan slice or rotation e CTDI mGy Volume CTDI also effective CTDI CTDI per scan e DLP mGy cm Dose length product based on CTDI per scan series a mSv Effective dose per scan series mSv Uterine dose per scan serie
68. this section the procedure to enter the data re quired for dose calculations is described step by step All cells into which data input has to be made are in white Those cells in grey contain other data which are also used for dose calculations and which only serve for information purposes Cells in which the results of dose calculations are displayed are in yel low All but the white cells are protected in order to avoid unintended changes Step 1 Selection of Patient Type 1 Age Group Patient Sex P J Adut y male a female Fig 4 1 Selection of patient type age group and sex User s Guide CT Expo V 2 3 Application Module Calculate The type of patient for which dose calculations shall be made is defined fig 4 1 by selecting e the age group adults children babies from the corresponding drop down menu and e the sex male female by clicking on the corre sponding button Step 2 Selection of Scan Range The scan range can directly be defined by entering the numerical values of the lower and the upper limit 2 Scan Range Get Values Fig 4 2 Selection of scan range by directly entering the numerical values of the lower and the upper limit of the scan range in the cells from z and to z By clicking on the area Get Values the content of these cells is replaced by the actual values which have been set up in the Scan Range sheets 13 of the scan
69. ults Selection of the Appropriate Worksheet From experience gained in the German MSCT sur vey at the beginning of 2002 it was felt to be more 31 User s Guide CT Expo V 2 3 Application Module Benchmarking appropriate to use separate worksheets for SSCT and MSCT scanners The selection of the appropriate worksheet is made automatically according to the type of scanner selected If another type of scanner is chosen later a prompt is given if necessary re quiring the user to switch to the corresponding benchmarking sheet fig 7 1 This is achieved by confirming the prompt Benchmarking of SSCT Scanners In this section the procedure to enter the data re quired for dose calculations is described step by step As many details are identical with the procedure in Attention G You have chosen a MSCT scanner on the single slice sheet Click on lt OK gt for changing to MSCT sheet Fig 7 1 A prompt which shows up if the worksheet is not ap propriate for the scanner selected the Calculate module only those items are men tioned here which are specific to this module Step 1 Selection of Scanner Model The selection of the scanner model is made in the same way as in the Calculate module fig 7 2 The presentation of scanner data fig 7 3 comprises all dose relevant specifications divided into the regions Head Neck and Body 15 Scanner Model Manufacturer Si
70. wn de pending on data input in N h and TF Note In order to calculate DLP and effective dose for routine brain examinations only half of the overranging is taken into account Step 5 Results The results of the dose calculations made in the Please Enter Actual Settings a Spiral Dose AL mm Imm mm mode modulat__ cm DEDOS La oso so ro sn ra mo am o os Ca aso veo foo o ss vo so sa on am 0 on Fig 5 5 Input cells in white used for entering the actual scan and examination parameters Different sets of parameters can be entered for up to three scan series If necessary the pre defined scan length values can be replaced by actual values enter ing zero restores the initial settings 23 User s Guide CT Expo V 2 3 Application Module Standard Standard module fig 5 6 are presented in similar form as in the Calculate module differences are as follows e The dose values resulting from the scan projec tion radiographs ae listed in addition e the results for each scan series are given separately e the values of the integral dose quantities DLP and E are given both for males and females e uterine dose is not given mSv following the German 3 stage model DGMP 2002 only in those examinations where the uterus is directly exposed The uterus is anatomically located at the level of the sacrum and lies within the scan range only for the total ab
71. y ref 43 User s Guide CT Expo V 2 3 Application Module Benchmarking 180 OCTDivol mDLPw _ O 140 120 100 80 Relative Dose 60 40 Standard Examinations Fig 7 10 Relative dose values for each type of examination in terms of volume CTDI CTDI and dose length product per examination DLP Bars exceeding the 100 line represent dose values above the average of the 99 German CT survey Contrary to the benchmarking of SSCT scanners the pitch corrected CTDI is used instead of CTDI 44 User s Guide CT Expo V 2 3 Application Module Benchmarking Printing the Results In order to send the benchmark results to your line printer please click on the area Prin in the naviga tion toolbar and select either Print Sheet or Print Diagram depending on whether you wish to hard copy the table or the figures In the same way other sheets like Calculate Stand ard and Comparison can also be printed Reset By clicking on the area Rese in the navigation tool bar all data entered in the white cells are erased im mediately The dose values in the yellow cells also disappear However as these cells are protected the algorithms programmed in these cells simply become invisible If you need to erase only a small amount of data first highlight the corresponding cells then push the Erase key on the keyboard of y
72. ystem or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without the prior written permission of the copyright holder of this work G Stamm Hannover and H D Nagel Buchholz Ist edition 2nd edition 3rd edition Ath edition 5th edition 6th edition August 2001 translated by H D Nagel and l Angelo Mysterioso April 2003 translated by H D Nagel and l Angelo Mysterioso November 2004 translated by H D Nagel November 2005 translated by H D Nagel November 2007 translated by H D Nagel January 2010 translated by H D Nagel 7th edition January 2011 translated by H D Nagel 8th edition May 2012 translated by H D Nagel 9th edition June 2013 translated by H D Nagel 10th edition April 2014 translated by H D Nagel Layout H D Nagel Hamburg on Apple Macintosh with Adobe PageMaker il User s Guide CT Expo V 2 3 License Conditions License Conditions This program used by you mentioned in the following as soft ware is shareware Use of this software requires the payment of the shareware fee to the company G Stamm in the follow ing mentioned as manufacturer For those users who have received the software from an authorised distributor free of charge the shareware fee is already paid All rights and conditions described in this license only apply to users registered by the manufacturer Registration requires the declarat

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