Dosimetric study of RapidArc plans and conventional intensity modulated radiotherapy for prostate cancer involving seminal vesicles and pelvis lymph nodes

Purpose: The main purpose of this study is to (1) identify the continual diversity between conventional fixed field intensity modulation radiotherapy (IMRT) and RapidArc (RA) for high-risk prostate cancer; and (2) determine potential benefits and drawbacks of using for this type of treatment.Methods: A cohort of 20 prostate cases including prostate, seminal vesicles and pelvic lymph nodes was selected for this study. The primary planning target volume (PTVP) and boost planning target volume (PTVB) were contoured. The total prescription dose was 75.6 Gy (45 Gy to PTVP and an additional 21.6 Gy to PTVB). Two plans were generated for each PTV: multiple 7-fields for IMRT and two arcs for RA.Results: A Sigma index (IMRT: 2.75 ± 0.581; RA: 2.8 ± 0.738) for PTVP and (IMRT: 2.0 ± 0.484; RA: 2.1 ± 0.464) for PTVB indicated similar dose homogeneity inside the PTV. Conformity index (IMRT: 0.96 ± 0.047; RA: 0.95 ± 0.059) for PTVP and (IMRT: 0.97 ± 0.015; RA: 0.96 ± 0.014) for PTVB was comparable for both the techniques. IMRT offered lower mean dose to organ at risks (OARs) compared to RA plans. Normal tissue integral dose in IMRT plan resulted 0.87% lower than RA plans. All the plans displayed significant increase (2.50 times for PTVP and 1.72 for PTBB) in the average number of necessary monitor units (MUs) with IMRT beam. Treatment delivery time of RA was 2 ‒ 6 minutes shorter than IMRT treatment.Conclusion: For PTV including pelvic lymph nodes, seminal vesicles and prostate, IMRT offered a greater degree of OARs sparing. For PTV including seminal vesicles and prostate, RA with two arcs provided comparable plan with IMRT. RA also improved the treatment efficiency due to smaller number of MUs required.</p

Dosimetric study of RapidArc plans and conventional intensity modulated radiotherapy for prostate cancer involving seminal vesicles and pelvis lymph nodes

Purpose: The main purpose of this study is to (1) identify the continual diversity between conventional fixed field intensity modulation radiotherapy (IMRT) and RapidArc (RA) for high-risk prostate cancer; and (2) determine potential benefits and drawbacks of using for this type of treatment.Methods: A cohort of 20 prostate cases including prostate, seminal vesicles and pelvic lymph nodes was selected for this study. The primary planning target volume (PTVP) and boost planning target volume (PTVB) were contoured. The total prescription dose was 75.6 Gy (45 Gy to PTVP and an additional 21.6 Gy to PTVB). Two plans were generated for each PTV: multiple 7-fields for IMRT and two arcs for RA.Results: A Sigma index (IMRT: 2.75 ± 0.581; RA: 2.8 ± 0.738) for PTVP and (IMRT: 2.0 ± 0.484; RA: 2.1 ± 0.464) for PTVB indicated similar dose homogeneity inside the PTV. Conformity index (IMRT: 0.96 ± 0.047; RA: 0.95 ± 0.059) for PTVP and (IMRT: 0.97 ± 0.015; RA: 0.96 ± 0.014) for PTVB was comparable for both the techniques. IMRT offered lower mean dose to organ at risks (OARs) compared to RA plans. Normal tissue integral dose in IMRT plan resulted 0.87% lower than RA plans. All the plans displayed significant increase (2.50 times for PTVP and 1.72 for PTBB) in the average number of necessary monitor units (MUs) with IMRT beam. Treatment delivery time of RA was 2 ‒ 6 minutes shorter than IMRT treatment.Conclusion: For PTV including pelvic lymph nodes, seminal vesicles and prostate, IMRT offered a greater degree of OARs sparing. For PTV including seminal vesicles and prostate, RA with two arcs provided comparable plan with IMRT. RA also improved the treatment efficiency due to smaller number of MUs required

Quality control test for electronic portal imaging device using QC-3 phantom with PIPSpro

Purpose:A Quality control (QC) test suitable for routinely daily use has been established for electronic portal imaging device (EPID) using PIPSpro software version 4.4 (Standard Imaging, Middleton, WI). It provides an objective and quantitative test for tolerable image quality on the basis of the high contrast spatial resolution, the contrast-to-noise ratio (CNR) and noise.Methods: The test uses a QC-3 phantom consisting of five sets of high contrast rectangular bar patterns with spatial frequeinces of 0.10, 0.20, 0.25, 0.43 and 0.75 lp/mm using 6MV and 15MV photon energy for accquiring high quality images. A “base line” value for the relative square wave modulation transfer function (RMTF), CNR and Noise data was obtained during a one week calibration period and one month test period.Results: Subsequent measurements shows significant deviations from baseline values, resulting in warning messages “potential problems in system performance”. The QC test uses high contrast spatial resolution and CNR for the system with acceptable performance. Conclusion: The method provides an automatic, objective, and sensitive measure of the system's imaging performance. This is a useful implementation during acceptance testing, commissioning, and routine quality control

Quality control test for electronic portal imaging device using QC-3 phantom with PIPSpro

Purpose:A Quality control (QC) test suitable for routinely daily use has been established for electronic portal imaging device (EPID) using PIPSpro software version 4.4 (Standard Imaging, Middleton, WI). It provides an objective and quantitative test for tolerable image quality on the basis of the high contrast spatial resolution, the contrast-to-noise ratio (CNR) and noise.Methods: The test uses a QC-3 phantom consisting of five sets of high contrast rectangular bar patterns with spatial frequeinces of 0.10, 0.20, 0.25, 0.43 and 0.75 lp/mm using 6MV and 15MV photon energy for accquiring high quality images. A “base line” value for the relative square wave modulation transfer function (RMTF), CNR and Noise data was obtained during a one week calibration period and one month test period.Results: Subsequent measurements shows significant deviations from baseline values, resulting in warning messages “potential problems in system performance”. The QC test uses high contrast spatial resolution and CNR for the system with acceptable performance. Conclusion: The method provides an automatic, objective, and sensitive measure of the system's imaging performance. This is a useful implementation during acceptance testing, commissioning, and routine quality control.</p