Range optimization for target and organs at risk in dynamic adaptive passive scattering proton beam therapy - A proof of concept

Shunsuke Moriya; Hidenobu Tachibana; Kenji Hotta; Naoki Nakamura; Takeji Sakae; Tetsuo Akimoto

doi:10.1016/j.ejmp.2018.11.010

Range optimization for target and organs at risk in dynamic adaptive passive scattering proton beam therapy - A proof of concept

Phys Med. 2018 Dec:56:66-73. doi: 10.1016/j.ejmp.2018.11.010. Epub 2018 Nov 27.

Authors

Shunsuke Moriya¹, Hidenobu Tachibana², Kenji Hotta³, Naoki Nakamura⁴, Takeji Sakae¹, Tetsuo Akimoto³

Affiliations

¹ Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8577, Japan.
² Division of Radiation Oncology and Particle Therapy, Exploratory Oncology Research & Clinical Trial Center, National Cancer Center, Chiba 277-8577, Japan; Radiation Safety and Quality Assurance Division, Hospital East, National Cancer Center, Chiba 277-8577, Japan. Electronic address: htachiba@east.ncc.go.jp.
³ Division of Radiation Oncology and Particle Therapy, Exploratory Oncology Research & Clinical Trial Center, National Cancer Center, Chiba 277-8577, Japan; Radiation Safety and Quality Assurance Division, Hospital East, National Cancer Center, Chiba 277-8577, Japan.
⁴ Division of Radiation Oncology and Particle Therapy, Exploratory Oncology Research & Clinical Trial Center, National Cancer Center, Chiba 277-8577, Japan; Department of Radiation Oncology, Hospital East, National Cancer Center, Chiba 277-8577, Japan.

PMID: 30527091
DOI: 10.1016/j.ejmp.2018.11.010

Abstract

Purpose: The purpose of this study was to design and develop a new range optimization for target and organs at risk (OARs) in dynamic adaptive proton beam therapy (PBT).

Methods: The new range optimization for target and OARs (RO-TO) was optimized to maintain target dose coverage but not to increase the dose exposure of OARs, while the other procedure, range optimization for target (RO-T), only focused on target dose coverage. A retrospective analysis of a patient who received PBT for abdominal lymph node metastases was performed to show the effectiveness of our new approach. The original plan (OP), which had a total dose of 60 Gy (relative biological effectiveness; RBE), was generated using six treatment fields. Bone-based registration (BR) and tumor-based registration (TR) were performed on each pretreatment daily CT image dataset acquired once every four fractions, to align the isocenter.

Results: Both range adaptive approaches achieved better coverage (D_95%) and homogeneity (D_5%-D_95%) than BR and TR only. However, RO-T showed the greatest increases in D_2cc and D_mean values of the small intestine and stomach and exceeded the limitations of dose exposure for those OARs. RO-TO showed comparable or superior dose sparing compared with the OP for all OARs.

Conclusions: Our results suggest that BR and TR alone may reduce target dose coverage, and that RO-T may increase the dose exposure to the OARs. RO-TO may achieve the planned dose delivery to the target and OARs more efficiently than the OP. The technique requires testing on a large clinical dataset.

Keywords: Abdominal cancer; Adaptive therapy; Image guidance; Proton beam therapy; Range optimization.

MeSH terms

Colonic Neoplasms / diagnostic imaging
Colonic Neoplasms / pathology
Colonic Neoplasms / radiotherapy
Humans
Lymphatic Metastasis / diagnostic imaging
Lymphatic Metastasis / radiotherapy
Organs at Risk*
Proof of Concept Study
Proton Therapy / methods*
Radiometry
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy, Image-Guided / methods
Retrospective Studies