Division of Radiation Oncology and Particle Therapy

Tetsuo Akimoto, Naoki Nakamura, Sadatomo Zenda, Hidenobu Tachibana, Kenji Hotta, Hiromi Baba, Motoki Kumagai

Introduction

The aim of research in the Division of Radiation Oncology and Particle Therapy at the National Cancer Center Hospital East (NCCHE) is to study and develop innovative treatment techniques and pilot a clinical trial for proton beam therapy (PBT). Medical physicists mainly perform the development and verification of the systems for beam irradiation, a dose calculation system, dose measurement, and imaging of PBT. Radiation oncologists mainly perform studies on the clinical trials, efficacy, and side-effects of PBT.

Our team and what we do

At present, the staff of the Division of Radiation Oncology and Particle Therapy consists of seven consultant physicians (radiation oncologists), six radiation technologists, four medical physicists, one nurse, and one clerk. We have more than 300 new patients for PBT every year, and quality assurances of PBT are performed by medical physicists and radiation technologists, and a conference on verification of treatment planning is held every morning in addition to a weekly work conference regarding research activities. PBT is routinely based on three-dimensional radiation therapy planning and PBT using RT-dedicated multi-detector-row helical computed tomography (CT) scanning in order to confirm a precise radiation dose to the targeted tumors. Respiratory-gating has been applied especially in radiotherapeutic management for patients with lung, esophagus, and liver cancers.

Our division is responsible for PBT that is composed of seven operating staff members and one technician for fabricating the compensator and aperture; they are sent from manufacturing companies and work in collaboration with other staff members of our division. PBT consists of two treatment rooms, both of which are routinely used for rotational gantry treatment. Our division ensures quality assurance and regular maintenance of the PBT machines for precise dose delivery and safe treatment.

Research activities

1)PBT as a nonsurgical approach to mucosal melanoma of the head and neck: a pilot study

2)Phase II study of PBT combined with chemotherapy for inoperable non-small cell lung cancer

3)Phase I/II study of dose escalated PBT combined with chemotherapy for esophageal cancer

4)Non-randomized prospective comparative study between surgical resection and PBT for resectable hepatocellular carcinoma

5)Establishment of feasibility and effectiveness of line scanning for localized prostate cancer

6)Proton dose distribution measurements using a MOSFET detector with a simple dose-weighted correction method for LET effects

7)Radiobiological evaluation of cellular response to PBT

8)Radiobiological evaluation of combined effect of chemotherapeutic agents on enhancement of PBT

9)Standardization of methods of PBT and quality assurance of PBT among Japanese proton beam facilities

10)Establishment of infrastructure for multi-institutional study of PBT for various cancers

11)Technical development of intensity modulated proton beam therapy (IMPT)

12)In silico comparison of dose distribution between IMRT and IMPT for locally advanced head and neck squamous cell carcinoma

Clinical trials

The following in-house and multi-institutional clinical trials are under way.

1)Phase II study of PBT for malignant melanoma of nasal cavity

2)Phase II study of PBT combined with chemotherapy for inoperable non-small cell lung cancer

3)Phase I/II study of dose escalated study of PBT combined with chemotherapy for esophageal cancer

4)Phase I/II study of line scanning for localized prostate cancer

5)Non-randomized prospective comparative study between surgical resection and PBT for resectable hepatocellular carcinoma

Education

We established an education and training system for residents and junior radiation oncologists through clinical conferences and lectures on radiation oncology, physics, and radiation biology. In addition, a training course regarding quality assurance of radiation therapy including PBT has been regularly held for medical physicists and radiological technologists.

Future prospects

We are now aiming at the establishment of a system that can provide high-quality and safe PBT. In addition, we would like to promote the research and development of innovative technologies regarding PBT, radiation biology, and medical physics.

Table 1. Changes in the number of patients treated with PBT