Evaluation of multiple institutions' models for knowledge-based planning of volumetric modulated arc therapy (VMAT) for prostate cancer

Yoshihiro Ueda; Jun-Ichi Fukunaga; Tatsuya Kamima; Yumiko Adachi; Kiyoshi Nakamatsu; Hajime Monzen

doi:10.1186/s13014-018-0994-1

Evaluation of multiple institutions' models for knowledge-based planning of volumetric modulated arc therapy (VMAT) for prostate cancer

Radiat Oncol. 2018 Mar 20;13(1):46. doi: 10.1186/s13014-018-0994-1.

Authors

Yoshihiro Ueda¹, Jun-Ichi Fukunaga², Tatsuya Kamima³, Yumiko Adachi⁴, Kiyoshi Nakamatsu⁵, Hajime Monzen⁶

Affiliations

¹ Department of Radiation Oncology, Osaka International Cancer Institute, 3-1-69 Otemae, Chuo-ku, Osaka, 537-8567, Japan.
² Divisin of Radiology, Department of Medical Technology, Kyushu University Hospital, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
³ Department of Radiation Oncology, Cancer Institute Hospital, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
⁴ Department of Radiology, Seirei Hamamatsu General Hospital, 2-12-12 Sumiyoshi, Naka Ward, Hamamatsu, Shizuoka, 430-8558, Japan.
⁵ Department of Radiation Oncology, Faculty of Medicine, Kindai University, 377-2 Ohno-higashi, Osakasayama, Osaka, 589-8511, Japan.
⁶ Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Ohno-higashi, Osakasayama, Osaka, 589-8511, Japan. hmon@med.kindai.ac.jp.

Abstract

Background: The aim of this study was to evaluate the performance of a commercial knowledge-based planning system, in volumetric modulated arc therapy for prostate cancer at multiple radiation therapy departments.

Methods: In each institute, > 20 cases were assessed. For the knowledge-based planning, the estimated dose (ED) based on geometric and dosimetric information of plans was generated in the model. Lower and upper limits of estimated dose were saved as dose volume histograms for each organ at risk. To verify whether the models performed correctly, KBP was compared with manual optimization planning in two cases. The relationships between the EDs in the models and the ratio of the OAR volumes overlapping volume with PTV to the whole organ volume (V_overlap/V_whole) were investigated.

Results: There were no significant dosimetric differences in OARs and PTV between manual optimization planning and knowledge-based planning. In knowledge-based planning, the difference in the volume ratio of receiving 90% and 50% of the prescribed dose (V90 and V50) between institutes were more than 5.0% and 10.0%, respectively. The calculated doses with knowledge-based planning were between the upper and lower limits of ED or slightly under the lower limit of ED. The relationships between the lower limit of ED and V_overlap/V_whole were different among the models. In the V90 and V50 for the rectum, the maximum differences between the lower limit of ED among institutes were 8.2% and 53.5% when V_overlap/V_whole for the rectum was 10%. In the V90 and V50 for the bladder, the maximum differences of the lower limit of ED among institutes were 15.1% and 33.1% when V_overlap/V_whole for the bladder was 10%.

Conclusion: Organs' upper and lower limits of ED in the models correlated closely with the V_overlap/V_whole. It is important to determine whether the models in KBP match a different institute's plan design before the models can be shared.

Keywords: Inverse planning; Knowledge-based planning; Prostate cancer; Quality assurance for planning; RapidPlan.

Publication types

Multicenter Study

MeSH terms

Humans
Male
Organs at Risk
Prostatic Neoplasms / radiotherapy*
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy, Intensity-Modulated / methods*