3D reconstruction of scintillation light emission from proton pencil beams using limited viewing angles-a simulation study

• Published in: Physics in medicine & biology 2014-08, Vol.59 (16), p.4477-4492
• Main Authors: Hui, CheukKai, Robertson, Daniel, Beddar, Sam
• Format: Article
• Language: English
• Subjects: 3D iterative reconstruction; Feasibility Studies; Humans; Light; liquid scintillation detector; Male; Monte Carlo Method; Physical Phenomena; Prostatic Neoplasms - radiotherapy; proton beam quality assurance; Proton Therapy - instrumentation; Quality Control; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted; Radiotherapy, Intensity-Modulated; Scintillation Counting - instrumentation
• ISSN: 0031-9155; 1361-6560
• DOI: 10.1088/0031-9155/59/16/4477

An accurate and high-resolution quality assurance (QA) method for proton radiotherapy beams is necessary to ensure correct dose delivery to the target. Detectors based on a large volume of liquid scintillator have shown great promise in providing fast and high-resolution measurements of proton treatment fields. However, previous work with these detectors has been limited to two-dimensional measurements, and the quantitative measurement of dose distributions was lacking. The purpose of the current study is to assess the feasibility of reconstructing three-dimensional (3D) scintillation light distributions of spot scanning proton beams using a scintillation system. The proposed system consists of a tank of liquid scintillator imaged by charge-coupled device cameras at three orthogonal viewing angles. Because of the limited number of viewing angles, we developed a profile-based technique to obtain an initial estimate that can improve the quality of the 3D reconstruction. We found that our proposed scintillator system and profile-based technique can reconstruct a single energy proton beam in 3D with a gamma passing rate (3%/3 mm local) of 100.0%. For a single energy layer of an intensity modulated proton therapy prostate treatment plan, the proposed method can reconstruct the 3D light distribution with a gamma pass rate (3%/3 mm local) of 99.7%. In addition, we also found that the proposed method is effective in detecting errors in the treatment plan, indicating that it can be a very useful tool for 3D proton beam QA.