BACKGROUND AND PURPOSE: Accurate delivery of radiotherapy is critical to achieve optimal treatment outcomes. Interfraction translational IGRT is now standard, and intrafraction motion management is becoming accessible. Some platforms can report both translational and rotational movements in real time. This study aims to quantify the dosimetric impact of observed intrafraction rotation of the prostate measured using monitoring software. MATERIALS AND METHODS: A dose grid resampling algorithm was used to model the dosimetric impact of prostate rotations for 20 patients on a SBRT prostate clinical trial. Translations were corrected before and during treatment, but rotations were not. Real time rotation data were acquired using KIM and a cumulative histogram analysis performed. Prostate volumes were rotated by the range of observed angles and used to calculate DVH data. RESULTS: The pitch axis had a higher range of observed rotations resulting in only 7 patients spending at least 90% of the beam on time across all fractions within rotation angles resulting in PTV D95% ≥36 Gy in this axis. The yaw and roll axes saw 17 and 15 patients respectively achieving this criterion. All but one of 20 patients exceeded CTV D98% ≥36 Gy for all observed rotation angles. CONCLUSIONS: Current CTV-PTV margins do not result in compromised CTV dose coverage due to inter and intrafraction prostate rotations in the absence of other uncertainties. Reduced PTV dosing is due to the extremely conformal treatment delivery but is unlikely to be clinically deleterious. Prostate standard IGRT should continue to focus on correcting any observed translational movements. Margin reduction could be explored in conjunction with other uncertainties.
BACKGROUND AND PURPOSE: Accurate delivery of radiotherapy is critical to achieve optimal treatment outcomes. Interfraction translational IGRT is now standard, and intrafraction motion management is becoming accessible. Some platforms can report both translational and rotational movements in real time. This study aims to quantify the dosimetric impact of observed intrafraction rotation of the prostate measured using monitoring software. MATERIALS AND METHODS: A dose grid resampling algorithm was used to model the dosimetric impact of prostate rotations for 20 patients on a SBRT prostate clinical trial. Translations were corrected before and during treatment, but rotations were not. Real time rotation data were acquired using KIM and a cumulative histogram analysis performed. Prostate volumes were rotated by the range of observed angles and used to calculate DVH data. RESULTS: The pitch axis had a higher range of observed rotations resulting in only 7 patients spending at least 90% of the beam on time across all fractions within rotation angles resulting in PTV D95% ≥36 Gy in this axis. The yaw and roll axes saw 17 and 15 patients respectively achieving this criterion. All but one of 20 patients exceeded CTV D98% ≥36 Gy for all observed rotation angles. CONCLUSIONS: Current CTV-PTV margins do not result in compromised CTV dose coverage due to inter and intrafraction prostate rotations in the absence of other uncertainties. Reduced PTV dosing is due to the extremely conformal treatment delivery but is unlikely to be clinically deleterious. Prostate standard IGRT should continue to focus on correcting any observed translational movements. Margin reduction could be explored in conjunction with other uncertainties.
Authors: Jarad Martin; Paul Keall; Shankar Siva; Peter Greer; David Christie; Kevin Moore; Jason Dowling; David Pryor; Peter Chong; Nicholas McLeod; Avi Raman; James Lynam; Joanne Smart; Christopher Oldmeadow; Colin I Tang; Declan G Murphy; Jeremy Millar; Keen Hun Tai; Lois Holloway; Penny Reeves; Amy Hayden; Tee Lim; Tanya Holt; Mark Sidhom Journal: BMJ Open Date: 2019-08-20 Impact factor: 2.692
Authors: Denis Panizza; Valeria Faccenda; Raffaella Lucchini; Martina Camilla Daniotti; Sara Trivellato; Paolo Caricato; Valerio Pisoni; Elena De Ponti; Stefano Arcangeli Journal: Front Oncol Date: 2022-04-07 Impact factor: 5.738
Authors: Casper Gammelmark Muurholm; Thomas Ravkilde; Robin De Roover; Simon Skouboe; Rune Hansen; Wouter Crijns; Tom Depuydt; Per R Poulsen Journal: Med Phys Date: 2022-04-25 Impact factor: 4.506
Authors: Alexandre Taillez; Andre-Michel Bimbai; Thomas Lacornerie; Marie-Cecile Le Deley; Eric F Lartigau; David Pasquier Journal: Front Oncol Date: 2021-07-14 Impact factor: 6.244