TY - JOUR
T1 - Online adaptive radiotherapy of anal cancer
T2 - Normal tissue sparing, target propagation methods, and first clinical experience
AU - Åström, Lina M.
AU - Behrens, Claus P.
AU - Storm, Katrine Smedegaard
AU - Sibolt, Patrik
AU - Serup-Hansen, Eva
N1 - Publisher Copyright:
© 2022 The Author(s)
PY - 2022/11
Y1 - 2022/11
N2 - Background and purpose: Online adaptive radiotherapy (oART) potentially spares OARs as PTV margins are reduced. This study evaluates dosimetric benefits, compared to standard non-adaptive radiotherapy (non-ART), target propagation methods, and first clinical treatments of CBCT-guided oART of anal cancer. Materials and methods: Treatment plans with standard non-ART and reduced oART PTV margins were retrospectively generated for 23 consecutive patients with anal cancer. For five patients randomly selected among the 23 patients, weekly CBCT-guided oART sessions were simulated, where the targets were either deformed or rigidly propagated. Preferred target propagation method and dose to OARs were evaluated. Ten consecutive patients with anal cancer were treated with CBCT-guided oART. Target propagation methods and oART procedure time were evaluated. Results: For the retrospective treatment plans, oART resulted in median reductions in bowel bag V45Gy of 11.4 % and bladder V35Gy of 16.1%. Corresponding values for the simulated sessions were 7.5% and 27.1%. In the simulated sessions, 35% of all targets were deformed while 65% were rigidly propagated. Manual editing and rigid propagation were necessary to obtain acceptable target coverage. In the clinical treatments, the primary and some elective targets were rigidly propagated, while other targets were deformed. The median oART procedure time, measured from CBCT acquisition to completion of plan review and QA, was 23 min. Conclusions: Simulated oART reduced the dose to OARs, indicating potential reduction in toxicity. Rigid propagation of targets was necessary to reduce the need for manual edit. Clinical treatments demonstrated that oART of anal cancer is feasible but time-consuming.
AB - Background and purpose: Online adaptive radiotherapy (oART) potentially spares OARs as PTV margins are reduced. This study evaluates dosimetric benefits, compared to standard non-adaptive radiotherapy (non-ART), target propagation methods, and first clinical treatments of CBCT-guided oART of anal cancer. Materials and methods: Treatment plans with standard non-ART and reduced oART PTV margins were retrospectively generated for 23 consecutive patients with anal cancer. For five patients randomly selected among the 23 patients, weekly CBCT-guided oART sessions were simulated, where the targets were either deformed or rigidly propagated. Preferred target propagation method and dose to OARs were evaluated. Ten consecutive patients with anal cancer were treated with CBCT-guided oART. Target propagation methods and oART procedure time were evaluated. Results: For the retrospective treatment plans, oART resulted in median reductions in bowel bag V45Gy of 11.4 % and bladder V35Gy of 16.1%. Corresponding values for the simulated sessions were 7.5% and 27.1%. In the simulated sessions, 35% of all targets were deformed while 65% were rigidly propagated. Manual editing and rigid propagation were necessary to obtain acceptable target coverage. In the clinical treatments, the primary and some elective targets were rigidly propagated, while other targets were deformed. The median oART procedure time, measured from CBCT acquisition to completion of plan review and QA, was 23 min. Conclusions: Simulated oART reduced the dose to OARs, indicating potential reduction in toxicity. Rigid propagation of targets was necessary to reduce the need for manual edit. Clinical treatments demonstrated that oART of anal cancer is feasible but time-consuming.
KW - Anal cancer
KW - Artificial intelligence
KW - Image-guided radiotherapy
KW - Normal tissue
KW - Online adaptive radiotherapy
KW - Re-optimization
UR - http://www.scopus.com/inward/record.url?scp=85139350886&partnerID=8YFLogxK
U2 - 10.1016/j.radonc.2022.09.015
DO - 10.1016/j.radonc.2022.09.015
M3 - Journal article
C2 - 36174846
AN - SCOPUS:85139350886
SN - 0167-8140
VL - 176
SP - 92
EP - 98
JO - Radiotherapy and Oncology
JF - Radiotherapy and Oncology
ER -