PURPOSE: To investigate dose deformation-invariance in adaptive prostate radiation treatment. METHODS: A 19 patient prostate cancer-cohort with 8-13 CTs/patient is used. The 79.2 Gy plans are developed on the reference image using seven 6 and 18 MV intensity-modulated beams with identical RTOG 0126 objectives. Dose on the subsequent images is evaluated in two ways: (A1) Dose is recalculated on each image. (A2) The initially planned dose distribution is copied to each image. A2 assumes dose-invariance in the accelerator-coordinate-system. Effects of patient miss-alignment are simulated by 27 per-patient image shifts; 0 and ±10 mm in left-right, anterior-posterior and superior-inferior directions. The per-voxel dose differences for each patient image, total accumulated patient dose, and dose-volume metrics (CTV-D98 and -D90, bladder- and rectum-D50, -D35, -D25 and -D15) are used to compare A1 and A2. RESULTS: The per-voxel mean percent difference in A1 and A2 dose over all patient images at 6 MV is (0.01±1.56)% and at 18 MV is (0.00±0.96)%. For 6 MV and 18 MV plans, the root-mean-square-percentage-error (RMSPE) in A2 over all patient image shifts are CTV-D98=0.94 and 0.55, CTV-D90=0.92 and 0.55, rectum-D50, -D35, -D25 and -D15=1.00, 0.96, 0.86, 0.80 and 0.84, 0.96, 0.92, 1.05; and bladder-D50, -D35, -D25, -D15=1.07, 0.88, 0.78, 0.72 and 1.61, 0.93, 0.67, 0.51. The dose differences are not correlated to the dice-similarity coefficients; with respective correlation-coefficients for CTV, rectum and bladder being -0.17, -0.17 and 0.081. CONCLUSIONS: Assumption of shift- and deformation-invariant dose distributions on an average introduces <2% error in evaluated dose-volume metrics for 6 and 18 MV IMRT prostate plans. Use of invariant dose distributions has a potential to reduce online re-planning time and permit pre-planning based on tissue deformation models.
PURPOSE: To investigate dose deformation-invariance in adaptive prostate radiation treatment. METHODS: A 19 patientprostate cancer-cohort with 8-13 CTs/patient is used. The 79.2 Gy plans are developed on the reference image using seven 6 and 18 MV intensity-modulated beams with identical RTOG 0126 objectives. Dose on the subsequent images is evaluated in two ways: (A1) Dose is recalculated on each image. (A2) The initially planned dose distribution is copied to each image. A2 assumes dose-invariance in the accelerator-coordinate-system. Effects of patient miss-alignment are simulated by 27 per-patient image shifts; 0 and ±10 mm in left-right, anterior-posterior and superior-inferior directions. The per-voxel dose differences for each patient image, total accumulated patient dose, and dose-volume metrics (CTV-D98 and -D90, bladder- and rectum-D50, -D35, -D25 and -D15) are used to compare A1 and A2. RESULTS: The per-voxel mean percent difference in A1 and A2 dose over all patient images at 6 MV is (0.01±1.56)% and at 18 MV is (0.00±0.96)%. For 6 MV and 18 MV plans, the root-mean-square-percentage-error (RMSPE) in A2 over all patient image shifts are CTV-D98=0.94 and 0.55, CTV-D90=0.92 and 0.55, rectum-D50, -D35, -D25 and -D15=1.00, 0.96, 0.86, 0.80 and 0.84, 0.96, 0.92, 1.05; and bladder-D50, -D35, -D25, -D15=1.07, 0.88, 0.78, 0.72 and 1.61, 0.93, 0.67, 0.51. The dose differences are not correlated to the dice-similarity coefficients; with respective correlation-coefficients for CTV, rectum and bladder being -0.17, -0.17 and 0.081. CONCLUSIONS: Assumption of shift- and deformation-invariant dose distributions on an average introduces <2% error in evaluated dose-volume metrics for 6 and 18 MV IMRT prostate plans. Use of invariant dose distributions has a potential to reduce online re-planning time and permit pre-planning based on tissue deformation models.
Authors: Raj Sripadam; Julie Stratford; Ann M Henry; Andrew Jackson; Chris J Moore; Pat Price Journal: Radiother Oncol Date: 2008-09-08 Impact factor: 6.280
Authors: Kirsten E I Deurloo; Roel J H M Steenbakkers; Lambert J Zijp; Josien A de Bois; Peter J C M Nowak; Coen R N Rasch; Marcel van Herk Journal: Int J Radiat Oncol Biol Phys Date: 2005-01-01 Impact factor: 7.038
Authors: Kelly H Zou; Simon K Warfield; Aditya Bharatha; Clare M C Tempany; Michael R Kaus; Steven J Haker; William M Wells; Ferenc A Jolesz; Ron Kikinis Journal: Acad Radiol Date: 2004-02 Impact factor: 3.173
Authors: Oscar Casares-Magaz; Ludvig P Muren; Niclas Pettersson; Maria Thor; Austin Hopper; Rick Knopp; Joseph O Deasy; Michael Væth; John Einck; Vitali Moiseenko Journal: Phys Imaging Radiat Oncol Date: 2018-10-05