Technical Innovations & Patient Support in Radiation Oncology (Sep 2023)

Synchronization of light flash with the irradiation pulse in proton beam therapy: A case report

  • Takashi Saito,
  • Masashi Mizumoto,
  • Yoshiko Oshiro,
  • Toshio Miyamoto,
  • Satoshi Kamizawa,
  • Masatoshi Nakamura,
  • Toshiki Ishida,
  • Hirokazu Makishima,
  • Haruko Numajiri,
  • Kei Nakai,
  • Takeji Sakae,
  • Hideyuki Sakurai

Journal volume & issue
Vol. 27
p. 100218

Abstract

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The correlation between sensory light flash and proton beam delivery was evaluated by measuring the timing of pulse beam delivery and light flash sensing using an event recorder in an 83-year-old patient receiving proton beam therapy (PBT) for nasopharyngeal adenoid cystic carcinoma. The treatment dose was 65 Gy (RBE) in 26 fractions with 2 ports, and both beams included the visual pathway (retina, optic nerve, chiasma). Measurements were obtained in 13 of the 26 fractions. The patient sensed a light flash in all 13 fractions and pressed the recorder button for 426 of the 430 pulsed beam deliveries, giving a sensing rate of 99.1%. The median duration of button-pressing of 0.3 s was almost the same as that of the beam pulse of 0.2 s, with a reaction time lag of 0.35 s. These results suggest a consistency between light flash during PBT and the timing of irradiation.

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