Katalin Kisivan1, Gergely Antal1, Akos Gulyban2, Csaba Glavak1, Zoltan Laszlo1, Judit Kalincsak1, Daniel Gugyeras1, Tibor Jenei3, Melinda Csima4, Ferenc Lakosi5. 1. Department of Radiation Oncology, Somogy County Mor Kaposi Teaching Hospital, Dr Jozsef Baka Center, Kaposvar, Hungary. 2. Medical Physics Department, Institut Jules Bordet, Bruxelles, Belgium. 3. Department of Urology, Somogy County Mor Kaposi Teaching Hospital, Kaposvar, Hungary. 4. Faculty of Pedagogy, Kaposvar University, Kaposvar, Hungary. 5. Department of Radiation Oncology, Somogy County Mor Kaposi Teaching Hospital, Dr Jozsef Baka Center, Kaposvar, Hungary. Electronic address: lakosiferenc@yahoo.com.
Abstract
PURPOSE: Our purpose was to investigate time efficiency and target coverage for prostate stereotactic ablative radiation therapy (SABR) using triggered imaging (TI) and auto beam hold. METHODS AND MATERIALS: A total of 20 patients were treated with volumetric modulated arc-based SABR. Treatment verification consisted of pre- and post-radiation therapy cone beam computed tomography (CBCT) with gold marker-based TI every 3 seconds. In case of ≥3 mm (deviation limit) displacement, the treatment was interrupted and imaging-based correction was performed. Beam interruptions, intrafractional shifts, and treatment times were recorded. Prostate, rectum, and bladder were delineated on each CBCT. Target coverage was evaluated by comparing the individual prostate delineations with 98% isodose contour volumes (% of the evaluated volumes exceeding the reference). Both inter- and intrafractional changes of bladder and rectal volumes were assessed. RESULTS: The average overall treatment time (±standard deviation) was 18 ± 11 min, with a radiation delivery time of 6 ± 3 min if no intrafractional CBCT acquisitions were necessary (91% of fractions). On average, 1.2 beam interruptions per fraction were required with 0/1 correction in 71% of the fractions. The mean residual 3-dimensional shift was 1.6 mm, exceeding the deviation limit in 8%. In the case of intrafractional CBCT and/or ≥2 corrections the treatment time dramatically increased. The 98% isodose lines did not encompass the prostate in only 8/180 (4%) evaluations in 6 different patients, leading to a loss of D98 between 0.1%-6% as a worst case scenario. The bladder volumes showed significant increases during treatment (P < .01) while rectal volumes were stable. CONCLUSIONS: Time efficiency of TI + auto beam hold with 3 mm/3 sec threshold during prostate SABR is comparable with competitive techniques, resulting in minimal 3-dimensional residual errors with maintained target coverage. Technical developments are necessary to further reduce radiation delivery time. Use of CBCT allowed full control of rectal volumes, while bladder volumes showed significant increases over time.
PURPOSE: Our purpose was to investigate time efficiency and target coverage for prostate stereotactic ablative radiation therapy (SABR) using triggered imaging (TI) and auto beam hold. METHODS AND MATERIALS: A total of 20 patients were treated with volumetric modulated arc-based SABR. Treatment verification consisted of pre- and post-radiation therapy cone beam computed tomography (CBCT) with gold marker-based TI every 3 seconds. In case of ≥3 mm (deviation limit) displacement, the treatment was interrupted and imaging-based correction was performed. Beam interruptions, intrafractional shifts, and treatment times were recorded. Prostate, rectum, and bladder were delineated on each CBCT. Target coverage was evaluated by comparing the individual prostate delineations with 98% isodose contour volumes (% of the evaluated volumes exceeding the reference). Both inter- and intrafractional changes of bladder and rectal volumes were assessed. RESULTS: The average overall treatment time (±standard deviation) was 18 ± 11 min, with a radiation delivery time of 6 ± 3 min if no intrafractional CBCT acquisitions were necessary (91% of fractions). On average, 1.2 beam interruptions per fraction were required with 0/1 correction in 71% of the fractions. The mean residual 3-dimensional shift was 1.6 mm, exceeding the deviation limit in 8%. In the case of intrafractional CBCT and/or ≥2 corrections the treatment time dramatically increased. The 98% isodose lines did not encompass the prostate in only 8/180 (4%) evaluations in 6 different patients, leading to a loss of D98 between 0.1%-6% as a worst case scenario. The bladder volumes showed significant increases during treatment (P < .01) while rectal volumes were stable. CONCLUSIONS: Time efficiency of TI + auto beam hold with 3 mm/3 sec threshold during prostate SABR is comparable with competitive techniques, resulting in minimal 3-dimensional residual errors with maintained target coverage. Technical developments are necessary to further reduce radiation delivery time. Use of CBCT allowed full control of rectal volumes, while bladder volumes showed significant increases over time.
Authors: Jihye Koo; Louis Nardella; Michael Degnan; Jacqueline Andreozzi; Hsiang-Hsuan M Yu; Jose Penagaricano; Peter A S Johnstone; Daniel Oliver; Kamran Ahmed; Stephen A Rosenberg; Evan Wuthrick; Roberto Diaz; Vladimir Feygelman; Kujtim Latifi; Eduardo G Moros; Gage Redler Journal: Technol Cancer Res Treat Date: 2021 Jan-Dec
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