Carbon range verification with 718\xa0keV Compton imaging

Raj Kumar Parajuli,Yoshiki Kubota,Nobuteru Kubo,Mutsumi Tashiro,Kazuo Arakawa,Makoto Sakai

doi:10.1038/s41598-021-00949-5

Abstract

Carbon ion radiotherapy is a sophisticated radiation treatment modality because of its superiority in achieving precise dosage distribution and high biological effectiveness. However, there exist beam range uncertainties that affect treatment efficiency. This problem can be resolved if the clinical beam could be monitored precisely in real-time, such as by imaging the prompt gamma emission from the target. In this study, we performed real-time detection and imaging of 718 keV prompt gamma emissions using a Si/CdTe Compton camera. We conducted experiments on graphite phantoms using clinical carbon ion beams of 290 MeV/u energy. Compton images were reconstructed using simple back-projection methods from the energy events of 718 keV prompt gamma emissions. The peak intensity position in reconstructed 718 keV prompt gamma images was few millimeters below the Bragg peak position. Moreover, the dual- and triple-energy window images for all positions of phantoms were not affected by scattered gammas, and their peak intensity positions were approximately similar to those observed in the reconstructed 718 keV prompt gamma images. In conclusion, the findings of the current study demonstrate the feasibility of using our Compton camera for real-time beam monitoring of carbon ion beams under clinical beam intensity.

Highlights

Carbon ion radiotherapy is a sophisticated radiation treatment modality because of its superiority in achieving precise dosage distribution and high biological effectiveness
A distinct energy peak of 718 keV was not visible in the energy spectrum (Fig. 2b), peak intensity positions of 718 keV prompt gamma emissions could be successfully observed in the reconstructed Compton images
This was because the background component of the signal detected by the Compton camera was large; the 718 keV signal was buried in the noise in the energy spectrum

Summary

Introduction

Carbon ion radiotherapy is a sophisticated radiation treatment modality because of its superiority in achieving precise dosage distribution and high biological effectiveness. There exist beam range uncertainties that affect treatment efficiency This problem can be resolved if the clinical beam could be monitored precisely in real-time, such as by imaging the prompt gamma emission from the target. Carbon ion radiotherapy (CIRT) is a widely accepted modality for the treatment of deeply seated tumors because of its high-dose localization around the Bragg peak (BP)[1] and its biological effectiveness[2,3,4,5] These unique properties make CIRT more sensitive to beam range u ncertainties[6,7,8]. One of the methods used to reduce uncertainties is the real-time monitoring of beams based on secondary radiation measurement In this regard, a positron emission tomography (PET) system is one of the potential s ystems[11,12,13,14,15,16].

Methods

Results

Conclusion