- Email: [email protected]
1040 poster Impact of urethrogram on prostate contouring
$436
1038 poster Cranial and extracranial stereotactic IMRT using the Varian 120-leaf MLC
S. Jaywant Cancer Institute of New Jersey~Robert Wood Johnson University Hospital, Radiation Oncology, New Brunswick (New Jersey), U.S.A. Introduction: Intensity modulated radiation therapy (IMRT) provides improved conformality in the dose distribution, reduces toxicity, allows dose escalation and hence improved tumor control. One of the several reasons for negative clinical outcome, when using IMRT, is inadequate patient immobilization and hence variability in the day to day positioning of the patient. This assumes greater importance when the fraction number is large, typically over 25, and the system becomes susceptible to increased positioning uncertainties due to either changes in the immobilization device or patient anatomy (loss of weight, swelling). Some of these issues are being addressed by resorting to daily imaging of the patient. A probable solution to this problem could be to use IMRT as a boost only. A better solution lies in incorporating stereotactic technology when delivering IMRT, which provides superior immobilization and localization. Materials and Method: The stereotactic IMRT technology is provided by Radionics and used on a Varian linac with a 120leaf MLC in the step and shoot mode. It utilizes, for cranial sIMRT, the GTC (adult) and TLC (pediatric) stereotactic frames, and, for extracranial targets, the HNL (Head and Neck Localizer) and BL (Body Localizer). The XknifeRT2.1 incorporates the necessary treatment planning tools. Stereotactic quality assurance phantoms that are specific to the frames, developed in-house and inexpensive, provide the dosimetric verification of the patient plans. Experience with the technology in the cranial region indicates that the "depth helmet" readings provide very accurate (1 mm) day to day reproducibility of the patient position and imaging is rarely required. In the Head and Neck region when using the HNL, however, it is important to corroborate the "depth" readings with once-a-week imaging and an accuracy of 2 mm is achievable. The BL currently does not provide any means of obtaining such "depth" readings and relies only on imaging. Hence a feature has been added to the BL that will allow for such observations to be recorded as well. This presentation will highlight the clinical use of s-IMRT in the brain, and, Head and Neck, (e.g. base of tongue and the neck). Some of the initial observations on the use of the Body Localizer will also be provided. 1039 poster Treatment technique
set-up verification: quality assurance for linac-based stereotactic : radiosurgerylradiotherapy using micro multi-leaf collimator
E. Lazaddis ~, K. Xydis 2, K. Theodorou 2, C. Kappas 2, M. Eble ~ University Hospital Aachen, Radiation Therapy, Aachen, Germany 2University Hospital Larissas, Radiation Therapy, Larissa, Hellas Isocenter accuracy and treatment set-up verification of stereotactic radiotherapy/radiosurgery procedure was examined with the classical optical and a new computational method. Linear accelerator stability was tested for possible sagging when the BrainLAB micro multi-leaf collimator (mMLC) was mounted. Isocentric shots were acquired on a series of radiographic films using the BrainLAB holder. A simple mathematical derivation was applied to measure distances of gantry deviation from the non-deviated origin
Posters
(classical optical method). Results were compared to data obtained from the identical test without the collimator mounted, as well as with the use of a different holder. Furthermore, the films were digitized and an algorithm was developed to assess algebraically uncertainties (computational method). After digitalization of the films to images, they were then analyzed through a special software tool, which converts each image to its numerical representation of pixel size, ranging from 0 to 255. Considering the reference distribution of pixel size as that in the case of zero-gantry angle (G = 0°), variations in pixel size in comparable regions for different angles were detected and calculated through the algorithm. The output from both visual and evaluative method was compared. Frequent repetitions of the so-called "Winston-Lutz" test, proved the necessity of this simple quality assurance test. Film digitalization should lead to more precise numerical determination of individual tests. Overall, the classical approach followed by an algebraic evaluation is a fairly satisfying quality assurance method for target verification and a very cost effective way to approve stereotactic treatments.
Target volume delineation 1040 poster Impact of urethrogram on prostate contouring
M. Liu 1, S. Kristensen ~, T. Currie 1, A. Agranovich ~, A. Karvat ~, W. Kwan ~, E. Kostashuk 1, M. Pc ~, E. Berthelet 2 ~BCCA, Fraser Valley Centre, Surrey, Canada 2BCCA, Vancouver Island Centre, Victoria, Canada Purpose: To determine if urethrogram impacts significantly on prostate contouring. Methods and Materials: Five patients undergoing radiotherapy for prostate cancer were randomly chosen. All had CT simulation (5ram slices) without and then with an urethrogram. The prostate was contoured on all CT's by 5 oncologists, blinded to patient identification. The contouring was repeated to account for intra-observer variation. Thus, a total of 100 prostate contours were obtained. The effects of urethrogram on prostate volume, superior-inferior (S-I), rightleft (R-L) and anterior-posterior (A-P) dimensions were measured. Results: The mean effect of urethrogram on prostate volume is +0.39% (+ve/-ve=increase/decrease of the particular measurements; range: +23.0% to -22.1%); effect on S-I: +0.031cm (range: +0.5cm to -0.75cm); R-L: +0.013cm (range: +0.7cm to -0.54cm); A-P:-0.108cm (range: +0.57cm to -0.63cm). Standard deviations are: 9.69%, 0.3cm, 0.32cm and 0.26cm respectively. The effect of urethrogram on individual oncologists' contours is small: range of mean volume change: +2.77% to -2.39%; range of mean measurement change S-I: +0.15cm to -0.05cm; R-L: +0.09cm to -0.12cm; A-P: +0.044cm to -0.28cm. The mean intraobserver variations without urethrogram are S-I: 2mm; R-L: 2.1mm; A-P: 1.8mm; as opposed to S-I: 1.4mm, R-L: 1.7mm; A-P: 2.5mm for those with urethrogram. Effect of urethrogram on individual patients is also small: range of mean volume change: +7.49% to -6.28%; S-I: +0.20cm to -0.09cm; R-L: +0.20cm to -0.19cm; A-P: +0.01 lcm to -0.29cm. Conclusions: Urethrogram does not affect prostate contouring significantly. Mean change of volume is only 0.39%.The mean change in dimensions in all directions are < l m m . The variations of S-I dimension are similar to those of R-L and A-P dimensions, thus supporting the effect of urethrogram on S-I measurements is minimal. Individual oncologists are not affected significantly by the use of
Posters
S437
urethrogram. Intra-observer variations are similar with and without urethrogram. 1041 poster
1042 poster
Internal target volume for oesophagus carcinoma F. Lorchel 1, J. Dumas ~, A. Noel 2-3, D. Wolf3, J. Bosset ~, P.
Delineation software for teaching in target volume definition J.C. Duppen 1, R.J.H.M. Steenbakkers ~, I. Fitton I, L.J. Zijp ~, P. Remeijer ~, K. De Jaeger ~, P.J.C.M. Nowak 2, C.R.N. Rasch ~, M. van Herk ~ The Netherlands Cancer Institute, Radiotherapy, Amsterdam, The Netherlands 2Erasmus University Medical Center- Dijkzigt, Radiotherapy, Rotterdam, The Netherlands Purpose: During delineation courses, hands-on training is
~University Hospital, Radiotherapy, Besangon, France 2Cancer Institute, Radiotherapy, Nancy, France 3Polytechnic National Institute of Lorraine, CRAN CNRS UMR 7039, Nancy, France Purpose: Chemoradiotherapy (CTRT) is the standard treatment for locally advanced oesophagus cancer. According to the ICRU-62 report, Planning Target Volume (PTV) delineation needs to know the organ motions during normal phases of breathing and set-up margins. With a view to suggest a PTV for conformational 3D radiotherapy (3D-RT) of oesophagus cancer, we analyzed motions of Gross Tumour Volume (GTV) and Clinical Target Volume (CTV) between exhale and inhale.
Materials and methods: Eight patients with squamous-cell carcinoma of the oesophagus were enrolled. Turnout location was: cervical (2), upper third (1), middle third (3) and lower third (2), We used a breath-hold technique with Dyn'R ° spirometer to performe dosimetric CT-scans at exhale, inhale and free breathing. Patients could control their own breathhold level with a video mobile personnal display. The same Oncologist (FL) drawned GTV and CTV delineation on each CT-scan. We evaluated the 3D-motions of GTV and CTV at 3 levels: superior, middle (isocentre) and inferior of the target volume, according to the ICRU recommandations. Moreover, we compared these motions with the amplitude of anteroposterior movements of xyphoid process, where we will put the box, with reflective markers of RPM system (Varian Medical Systems °) for gating. Results:Mean 3D movements (in cm) of GTV and CTV at the top, at the isocenter and at the bottom of the target volume are reported in table 1. Overall, motion of GTV and CTV is in inferior and left direction between exhale and inhale. Data of motion range from 0 to 15 mm in absolute value. Ninety five per cent of values range from O to 10 mm. Table 1 : ............ i ~
Motions[ Sup ANT
.......................................... ~ c ~ v
~isocentre
0.09 :I +0 66 0.31 +0.44
nf
& Sup
0.15-0.06 +0 27 +0 14
00 +021%6 i
patients are needed to try to find differences between turnout levels.
001 LATR I~+"
~_0.18
-035+054 -
............................................
j
Isocentre
Inf
:! + 0.05_0.13
-0.1 +0 43
005+03
-0~6 1-02 +" +" i 0 . 3 2 _0.47
~-016+046 0+"0 4 _0.46i
-0.19 -0.28 LAT L i+0.23-011 i-0.33 -+0.29 I+0.51 ,. . . . +0.38
~ I0 -+0 "68
i0.15 +0.52
i!
'
I-0.19 • +0.43
INF
;~ '
~
;
" -0.07 ~+0.17
~
'
There is a trend for a correlation between the anteroposterior movements of CTV, GTV and xyphoid process, but amplitude is higher for xyphoid process (0,41 cm _+0.31).
Conclusion: To take into account 95% of the motions, an ITV of 10 mm must be chosen for PTV suggestion. More
desirable but difficult to organize. For this reason, we developed delineation software for target volumes that is suitable both for homework and for application during teaching courses, such as the ESTRO teaching course: "Imaging for target volume determination in radiotherapy".
Materials and methods: The delineation software (Fig. 1) contains the usual delineation tools provided by most commercial planning systems. The main window shows the CT slices for delineation, while side windows show sagittal and coronal reconstructions. In some cases an additional window is available with matched MRI or FDG-PET scans. The software was distributed on CD to the participants prior to the ESTRO teaching course. No installation is needed and the program starts automatically. The students were asked to delineate GTV and/or CTV for head and neck, brain, lung and prostate patients. All participants received a private access code to create, edit and view their own set of contours and were not able to see the work of other participants. After delineation, the contours were submitted through the Internet. During delineation, the software recorded all user actions for later analysis. The teacher version of the software had additional functions: it could replay the whole process of delineation, and it could display delineations from multiple observers at the same time. During the ESTRO course, ten groups of fifteen participants were asked to delineate and discuss the same patients again using a single computer per group. At the end of the course a second password was provided allowing joint display of the students and teacher's work.
Results: For the delineations that were made prior to the ESTRO teaching course, large variations were observed. For example, for the prostate patient, some participants included all pelvic lymph nodes into the CTV and others delineated the prostate only. During the teaching course, the participants in the groups were asked to discuss with each other during delineation, leading to better agreement among the different groups. Subsequent discussions between students, and teachers (both oncologists and diagnosticians), using the same software, lead to further consensus.
Conclusions: We developed software for delineation of target volumes specifically suited for teaching purposes. Group discussion about the delineations resulted in a significant reduction of observer variation.
1038 poster Cranial and extracranial stereotactic IMRT using the Varian 120-leaf MLC
S. Jaywant Cancer Institute of New Jersey~Robert Wood Johnson University Hospital, Radiation Oncology, New Brunswick (New Jersey), U.S.A. Introduction: Intensity modulated radiation therapy (IMRT) provides improved conformality in the dose distribution, reduces toxicity, allows dose escalation and hence improved tumor control. One of the several reasons for negative clinical outcome, when using IMRT, is inadequate patient immobilization and hence variability in the day to day positioning of the patient. This assumes greater importance when the fraction number is large, typically over 25, and the system becomes susceptible to increased positioning uncertainties due to either changes in the immobilization device or patient anatomy (loss of weight, swelling). Some of these issues are being addressed by resorting to daily imaging of the patient. A probable solution to this problem could be to use IMRT as a boost only. A better solution lies in incorporating stereotactic technology when delivering IMRT, which provides superior immobilization and localization. Materials and Method: The stereotactic IMRT technology is provided by Radionics and used on a Varian linac with a 120leaf MLC in the step and shoot mode. It utilizes, for cranial sIMRT, the GTC (adult) and TLC (pediatric) stereotactic frames, and, for extracranial targets, the HNL (Head and Neck Localizer) and BL (Body Localizer). The XknifeRT2.1 incorporates the necessary treatment planning tools. Stereotactic quality assurance phantoms that are specific to the frames, developed in-house and inexpensive, provide the dosimetric verification of the patient plans. Experience with the technology in the cranial region indicates that the "depth helmet" readings provide very accurate (1 mm) day to day reproducibility of the patient position and imaging is rarely required. In the Head and Neck region when using the HNL, however, it is important to corroborate the "depth" readings with once-a-week imaging and an accuracy of 2 mm is achievable. The BL currently does not provide any means of obtaining such "depth" readings and relies only on imaging. Hence a feature has been added to the BL that will allow for such observations to be recorded as well. This presentation will highlight the clinical use of s-IMRT in the brain, and, Head and Neck, (e.g. base of tongue and the neck). Some of the initial observations on the use of the Body Localizer will also be provided. 1039 poster Treatment technique
set-up verification: quality assurance for linac-based stereotactic : radiosurgerylradiotherapy using micro multi-leaf collimator
E. Lazaddis ~, K. Xydis 2, K. Theodorou 2, C. Kappas 2, M. Eble ~ University Hospital Aachen, Radiation Therapy, Aachen, Germany 2University Hospital Larissas, Radiation Therapy, Larissa, Hellas Isocenter accuracy and treatment set-up verification of stereotactic radiotherapy/radiosurgery procedure was examined with the classical optical and a new computational method. Linear accelerator stability was tested for possible sagging when the BrainLAB micro multi-leaf collimator (mMLC) was mounted. Isocentric shots were acquired on a series of radiographic films using the BrainLAB holder. A simple mathematical derivation was applied to measure distances of gantry deviation from the non-deviated origin
Posters
(classical optical method). Results were compared to data obtained from the identical test without the collimator mounted, as well as with the use of a different holder. Furthermore, the films were digitized and an algorithm was developed to assess algebraically uncertainties (computational method). After digitalization of the films to images, they were then analyzed through a special software tool, which converts each image to its numerical representation of pixel size, ranging from 0 to 255. Considering the reference distribution of pixel size as that in the case of zero-gantry angle (G = 0°), variations in pixel size in comparable regions for different angles were detected and calculated through the algorithm. The output from both visual and evaluative method was compared. Frequent repetitions of the so-called "Winston-Lutz" test, proved the necessity of this simple quality assurance test. Film digitalization should lead to more precise numerical determination of individual tests. Overall, the classical approach followed by an algebraic evaluation is a fairly satisfying quality assurance method for target verification and a very cost effective way to approve stereotactic treatments.
Target volume delineation 1040 poster Impact of urethrogram on prostate contouring
M. Liu 1, S. Kristensen ~, T. Currie 1, A. Agranovich ~, A. Karvat ~, W. Kwan ~, E. Kostashuk 1, M. Pc ~, E. Berthelet 2 ~BCCA, Fraser Valley Centre, Surrey, Canada 2BCCA, Vancouver Island Centre, Victoria, Canada Purpose: To determine if urethrogram impacts significantly on prostate contouring. Methods and Materials: Five patients undergoing radiotherapy for prostate cancer were randomly chosen. All had CT simulation (5ram slices) without and then with an urethrogram. The prostate was contoured on all CT's by 5 oncologists, blinded to patient identification. The contouring was repeated to account for intra-observer variation. Thus, a total of 100 prostate contours were obtained. The effects of urethrogram on prostate volume, superior-inferior (S-I), rightleft (R-L) and anterior-posterior (A-P) dimensions were measured. Results: The mean effect of urethrogram on prostate volume is +0.39% (+ve/-ve=increase/decrease of the particular measurements; range: +23.0% to -22.1%); effect on S-I: +0.031cm (range: +0.5cm to -0.75cm); R-L: +0.013cm (range: +0.7cm to -0.54cm); A-P:-0.108cm (range: +0.57cm to -0.63cm). Standard deviations are: 9.69%, 0.3cm, 0.32cm and 0.26cm respectively. The effect of urethrogram on individual oncologists' contours is small: range of mean volume change: +2.77% to -2.39%; range of mean measurement change S-I: +0.15cm to -0.05cm; R-L: +0.09cm to -0.12cm; A-P: +0.044cm to -0.28cm. The mean intraobserver variations without urethrogram are S-I: 2mm; R-L: 2.1mm; A-P: 1.8mm; as opposed to S-I: 1.4mm, R-L: 1.7mm; A-P: 2.5mm for those with urethrogram. Effect of urethrogram on individual patients is also small: range of mean volume change: +7.49% to -6.28%; S-I: +0.20cm to -0.09cm; R-L: +0.20cm to -0.19cm; A-P: +0.01 lcm to -0.29cm. Conclusions: Urethrogram does not affect prostate contouring significantly. Mean change of volume is only 0.39%.The mean change in dimensions in all directions are < l m m . The variations of S-I dimension are similar to those of R-L and A-P dimensions, thus supporting the effect of urethrogram on S-I measurements is minimal. Individual oncologists are not affected significantly by the use of
Posters
S437
urethrogram. Intra-observer variations are similar with and without urethrogram. 1041 poster
1042 poster
Internal target volume for oesophagus carcinoma F. Lorchel 1, J. Dumas ~, A. Noel 2-3, D. Wolf3, J. Bosset ~, P.
Delineation software for teaching in target volume definition J.C. Duppen 1, R.J.H.M. Steenbakkers ~, I. Fitton I, L.J. Zijp ~, P. Remeijer ~, K. De Jaeger ~, P.J.C.M. Nowak 2, C.R.N. Rasch ~, M. van Herk ~ The Netherlands Cancer Institute, Radiotherapy, Amsterdam, The Netherlands 2Erasmus University Medical Center- Dijkzigt, Radiotherapy, Rotterdam, The Netherlands Purpose: During delineation courses, hands-on training is
~University Hospital, Radiotherapy, Besangon, France 2Cancer Institute, Radiotherapy, Nancy, France 3Polytechnic National Institute of Lorraine, CRAN CNRS UMR 7039, Nancy, France Purpose: Chemoradiotherapy (CTRT) is the standard treatment for locally advanced oesophagus cancer. According to the ICRU-62 report, Planning Target Volume (PTV) delineation needs to know the organ motions during normal phases of breathing and set-up margins. With a view to suggest a PTV for conformational 3D radiotherapy (3D-RT) of oesophagus cancer, we analyzed motions of Gross Tumour Volume (GTV) and Clinical Target Volume (CTV) between exhale and inhale.
Materials and methods: Eight patients with squamous-cell carcinoma of the oesophagus were enrolled. Turnout location was: cervical (2), upper third (1), middle third (3) and lower third (2), We used a breath-hold technique with Dyn'R ° spirometer to performe dosimetric CT-scans at exhale, inhale and free breathing. Patients could control their own breathhold level with a video mobile personnal display. The same Oncologist (FL) drawned GTV and CTV delineation on each CT-scan. We evaluated the 3D-motions of GTV and CTV at 3 levels: superior, middle (isocentre) and inferior of the target volume, according to the ICRU recommandations. Moreover, we compared these motions with the amplitude of anteroposterior movements of xyphoid process, where we will put the box, with reflective markers of RPM system (Varian Medical Systems °) for gating. Results:Mean 3D movements (in cm) of GTV and CTV at the top, at the isocenter and at the bottom of the target volume are reported in table 1. Overall, motion of GTV and CTV is in inferior and left direction between exhale and inhale. Data of motion range from 0 to 15 mm in absolute value. Ninety five per cent of values range from O to 10 mm. Table 1 : ............ i ~
Motions[ Sup ANT
.......................................... ~ c ~ v
~isocentre
0.09 :I +0 66 0.31 +0.44
nf
& Sup
0.15-0.06 +0 27 +0 14
00 +021%6 i
patients are needed to try to find differences between turnout levels.
001 LATR I~+"
~_0.18
-035+054 -
............................................
j
Isocentre
Inf
:! + 0.05_0.13
-0.1 +0 43
005+03
-0~6 1-02 +" +" i 0 . 3 2 _0.47
~-016+046 0+"0 4 _0.46i
-0.19 -0.28 LAT L i+0.23-011 i-0.33 -+0.29 I+0.51 ,. . . . +0.38
~ I0 -+0 "68
i0.15 +0.52
i!
'
I-0.19 • +0.43
INF
;~ '
~
;
" -0.07 ~+0.17
~
'
There is a trend for a correlation between the anteroposterior movements of CTV, GTV and xyphoid process, but amplitude is higher for xyphoid process (0,41 cm _+0.31).
Conclusion: To take into account 95% of the motions, an ITV of 10 mm must be chosen for PTV suggestion. More
desirable but difficult to organize. For this reason, we developed delineation software for target volumes that is suitable both for homework and for application during teaching courses, such as the ESTRO teaching course: "Imaging for target volume determination in radiotherapy".
Materials and methods: The delineation software (Fig. 1) contains the usual delineation tools provided by most commercial planning systems. The main window shows the CT slices for delineation, while side windows show sagittal and coronal reconstructions. In some cases an additional window is available with matched MRI or FDG-PET scans. The software was distributed on CD to the participants prior to the ESTRO teaching course. No installation is needed and the program starts automatically. The students were asked to delineate GTV and/or CTV for head and neck, brain, lung and prostate patients. All participants received a private access code to create, edit and view their own set of contours and were not able to see the work of other participants. After delineation, the contours were submitted through the Internet. During delineation, the software recorded all user actions for later analysis. The teacher version of the software had additional functions: it could replay the whole process of delineation, and it could display delineations from multiple observers at the same time. During the ESTRO course, ten groups of fifteen participants were asked to delineate and discuss the same patients again using a single computer per group. At the end of the course a second password was provided allowing joint display of the students and teacher's work.
Results: For the delineations that were made prior to the ESTRO teaching course, large variations were observed. For example, for the prostate patient, some participants included all pelvic lymph nodes into the CTV and others delineated the prostate only. During the teaching course, the participants in the groups were asked to discuss with each other during delineation, leading to better agreement among the different groups. Subsequent discussions between students, and teachers (both oncologists and diagnosticians), using the same software, lead to further consensus.
Conclusions: We developed software for delineation of target volumes specifically suited for teaching purposes. Group discussion about the delineations resulted in a significant reduction of observer variation.