Sensitivity improvement of YAP(Ce) cameras for imaging of secondary electron bremsstrahlung X-rays emitted during carbon-ion irradiation: Problem and solution

Seiichi Yamamoto, Mitsutaka Yamaguchi, Takashi Akagi, Maki Kitano, Naoki Kawachi

研究成果: Article査読

4 被引用数 (Scopus)

抄録

Low-energy X-ray imaging of secondary electron bremsstrahlung X-rays emitted during carbon-ion irradiation is a promising method for range estimation and could be used for imaging with almost clinical dose levels of carbon ion. However, the number of counts in images with clinical dose levels is relatively small, making it difficult to obtain precise range estimations. Since improving the sensitivity of the X-ray camera may solve this issue, we developed two new types of X-ray cameras. One uses a 1 mm thick, 40 mm × 40 mm cerium-doped yttrium aluminum perovskite (YA1O3: YAP(Ce)) scintillator plate combined with a 2 inch square flat panel photomultiplier tube (FP-PMT) contained in a 2 cm thick tungsten shield with a pinhole collimator positioned 50 mm from the scintillator; the other uses a 0.5 mm thick, 20 mm × 20 mm YAP(Ce) scintillator plate combined with a 1 inch square position sensitive photomultiplier tube (PSPMT) contained in the same tungsten shield with a pinhole collimator, but with the scintillator positioned closer (30 mm) to the pinhole collimator to obtain a similar field of view. For both cameras, we used a wider angle (∼55°) pinhole collimator to measure the phantom closer to improve sensitivity. Although the 40 mm × 40 mm YAP(Ce) camera had high system spatial resolution, the background count fractions were high and produced a high count area at the center of the images due to the pulse pileup of the signals. With the 20 mm × 20 mm YAP(Ce) camera, we obtained X-ray images with low background counts without a high count area at the image center. By smoothing the measured images, we were able to estimate the ranges even for clinical dose levels. We therefore confirmed that one of our newly developed YAP(Ce) cameras had high sensitivity and is promising for the imaging of secondary electron bremsstrahlung X-rays during irradiation of carbon ions in clinical conditions.

本文言語English
論文番号105008
ジャーナルPhysics in Medicine and Biology
65
10
DOI
出版ステータスPublished - 2020 5月 21
外部発表はい

ASJC Scopus subject areas

  • 放射線技術および超音波技術
  • 放射線学、核医学およびイメージング

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