Monitoring of positron using high-energy gamma camera for proton therapy

Seiichi Yamamoto, Toshiyuki Toshito, Masataka Komori, Yuki Morishita, Satoshi Okumura, Mitsutaka Yamaguchi, Yuichi Saito, Naoki Kawachi, Shu Fujimaki

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Purpose: 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. Methods: 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. Results: 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. Conclusions: These results indicate that the developed high-energy gamma camera is useful for imaging positron distributions in proton therapy.

Original languageEnglish
Pages (from-to)268-275
Number of pages8
JournalAnnals of Nuclear Medicine
Volume29
Issue number3
DOIs
Publication statusPublished - 01-04-2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Radiology Nuclear Medicine and imaging

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    Yamamoto, S., Toshito, T., Komori, M., Morishita, Y., Okumura, S., Yamaguchi, M., Saito, Y., Kawachi, N., & Fujimaki, S. (2015). Monitoring of positron using high-energy gamma camera for proton therapy. Annals of Nuclear Medicine, 29(3), 268-275. https://doi.org/10.1007/s12149-014-0936-4