1. Monitoring of positron using high-energy gamma camera for proton therapy
- Author
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Masataka Komori, Mitsutaka Yamaguchi, Shu Fujimaki, Yuichi Saito, Satoshi Okumura, Seiichi Yamamoto, Yuki Morishita, Naoki Kawachi, and Toshiyuki Toshito
- Subjects
Astrophysics::High Energy Astrophysical Phenomena ,Physics::Medical Physics ,Electrons ,Scintillator ,Imaging phantom ,law.invention ,Optics ,Positron ,law ,Proton Therapy ,medicine ,Humans ,Gamma Cameras ,Radiology, Nuclear Medicine and imaging ,Image resolution ,Proton therapy ,Gamma camera ,medicine.diagnostic_test ,Phantoms, Imaging ,Sodium Radioisotopes ,business.industry ,Collimator ,Equipment Design ,General Medicine ,Positron emission tomography ,Physics::Accelerator Physics ,business ,Nuclear medicine - Abstract
In proton therapy, imaging of proton-induced positrons is a useful method to monitor the proton beam distribution after therapy. Usually, a positron emission tomography (PET) system installed in or near the proton beam treatment room is used for this purpose. However, a PET system is sometimes too large and expensive for this purpose. We developed a small field-of-view (FOV) gamma camera for high-energy gamma photons and used it for monitoring the proton-induced positron distribution. The gamma camera used 0.85 mm × 0.85 mm × 10 mm Ce:Gd3Al2Ga3O12 (GAGG) pixels arranged in 20 × 20 matrix to form a scintillator block, which was optically coupled to a 1-inch-square position-sensitive photomultiplier tube (PSPMT). The GAGG detector was encased in a 20-mm thick container and a pinhole collimator was mounted on its front. The gamma camera was set 1.2 m from the 35 cm × 35 cm × 5 cm plastic phantom in the proton therapy treatment room, and proton beams were irradiated to the phantom with two proton energies. The gamma camera had spatial resolution of ~6.7 cm and sensitivity of 3.2 × 10−7 at 1 m from the collimator surface. For both proton energies, positron distribution in the phantom could be imaged by the gamma camera with 10-min acquisition. The lengths of the range of protons measured from the images were almost identical to the simulation results. These results indicate that the developed high-energy gamma camera is useful for imaging positron distributions in proton therapy.
- Published
- 2014