TY - JOUR
T1 - Evaluation of daily online contour adaptation by radiation therapists for prostate cancer treatment on an MRI-guided linear accelerator
AU - Willigenburg, Thomas
AU - de Muinck Keizer, Daan M
AU - Peters, Max
AU - Claes, An
AU - Lagendijk, Jan J W
AU - de Boer, Hans C J
AU - van der Voort van Zyp, Jochem R N
N1 - Funding Information:
This research has been partly funded by ZonMW IMDI/LSH-TKI Foundation (The Netherlands, project number 104006004). The funding sources had no involvement in the design of the study, the collection, analysis, and interpretation of the data, nor in the writing and decision to submit the article for publication.
Publisher Copyright:
© 2021 The Author(s)
PY - 2021/3
Y1 - 2021/3
N2 - Background and purpose: Magnetic resonance (MR)-guided linear accelerator (MR-Linac) systems have changed radiotherapy workflows. The addition of daily online contour adaptation allows for higher precision treatment, but also increases the workload of those involved. We train radiation therapists (RTTs) to perform daily online contour adaptation for MR-Linac treatment of prostate cancer (PCa) patients. The purpose of this study was to evaluate these prostate contours by performing an interfraction and interobserver analysis.Materials and methods: Clinical target volume (CTV) contours generated online by RTTs from 30 low-intermediate risk PCa patients, treated with 5x7.25 Gy, were used. Two physicians (Observers) judged the RTTs contours and performed adaptations when necessary. Interfraction relative volume differences between the first and the subsequent fractions were calculated for the RTTs, Observer 1, and Observer 2. Additionally, interobserver dice's similarity coefficient (DSC) for fraction 2-5 was calculated with the RTTs- and physician-adapted contours. Clinical acceptability of the RTTs contours was judged by a third observer.Results: Mean (SD) online contour adaptation time was 12.6 (±3.8) minutes and overall median (interquartile range [IQR]) relative volume difference was 9.3% (4.4-13.0). Adaptations by the observers were mostly performed at the apex and base of the prostate. Median (IQR) interobserver DSC between RTTs and Observer 1, RTTs and Observer 2, and Observer 1 and 2 was 0.99 (0.98-1.00), 1.00 (0.98-1.00), and 1.00 (0.99-1.00), respectively. Contours were acceptable for clinical use in 113 (94.2%) fractions. Dose-volume histogram (DVH) analysis showed significant CTV underdosage for one of the seven identified outliers.Conclusion: Daily online contour adaptation by RTTs is clinically feasible for MR-Linac treatment of PCa.
AB - Background and purpose: Magnetic resonance (MR)-guided linear accelerator (MR-Linac) systems have changed radiotherapy workflows. The addition of daily online contour adaptation allows for higher precision treatment, but also increases the workload of those involved. We train radiation therapists (RTTs) to perform daily online contour adaptation for MR-Linac treatment of prostate cancer (PCa) patients. The purpose of this study was to evaluate these prostate contours by performing an interfraction and interobserver analysis.Materials and methods: Clinical target volume (CTV) contours generated online by RTTs from 30 low-intermediate risk PCa patients, treated with 5x7.25 Gy, were used. Two physicians (Observers) judged the RTTs contours and performed adaptations when necessary. Interfraction relative volume differences between the first and the subsequent fractions were calculated for the RTTs, Observer 1, and Observer 2. Additionally, interobserver dice's similarity coefficient (DSC) for fraction 2-5 was calculated with the RTTs- and physician-adapted contours. Clinical acceptability of the RTTs contours was judged by a third observer.Results: Mean (SD) online contour adaptation time was 12.6 (±3.8) minutes and overall median (interquartile range [IQR]) relative volume difference was 9.3% (4.4-13.0). Adaptations by the observers were mostly performed at the apex and base of the prostate. Median (IQR) interobserver DSC between RTTs and Observer 1, RTTs and Observer 2, and Observer 1 and 2 was 0.99 (0.98-1.00), 1.00 (0.98-1.00), and 1.00 (0.99-1.00), respectively. Contours were acceptable for clinical use in 113 (94.2%) fractions. Dose-volume histogram (DVH) analysis showed significant CTV underdosage for one of the seven identified outliers.Conclusion: Daily online contour adaptation by RTTs is clinically feasible for MR-Linac treatment of PCa.
KW - Adapt-to-shape
KW - MR-Linac
KW - MRI-guided radiotherapy
KW - Online contour adaptation
KW - Prostate cancer
KW - Radiation therapists
UR - http://www.scopus.com/inward/record.url?scp=85099607968&partnerID=8YFLogxK
U2 - 10.1016/j.ctro.2021.01.002
DO - 10.1016/j.ctro.2021.01.002
M3 - Article
C2 - 33532630
SN - 2405-6308
VL - 27
SP - 50
EP - 56
JO - Clinical and translational radiation oncology
JF - Clinical and translational radiation oncology
ER -