Clinical application of a gantry-attachable plastic scintillating plate dosimetry system in pencil beam scanning proton therapy beam monitoring

Seonghoon Jeong, Myonggeun Yoon, Kwangzoo Chung, Sung Hwan Ahn, Boram Lee, Jaehyeon Seo

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Purpose: The entrance beam fluence of therapeutic proton scanning beams can be monitored using a gantry-attachable plastic scintillating plate (GAPSP). This study evaluated the clinical application of the GAPSP using a method that measures intensity modulated proton therapy (IMPT) beams for patient treatment. Methods: IMPT beams for the treatment of nine patients, at sites that included the spine, head and neck, pelvis, and lung, were measured using the GAPSP, composed of an EJ-212 plastic scintillator and a CMOS camera. All energy layers distinguished by the GAPSP were accumulated to determine the dose distribution of the treatment field. The evaluated fields were compared with reference dose maps verified by quality assurance. Results: Comparison of dose distributions of evaluation treatment fields with reference dose distributions showed that the 3%/1 mm average gamma passing rate was 96.4%, independent of the treatment site, energy range and field size. When dose distributions were evaluated using the same criteria for each energy layer, the average gamma passing rate was 91.7%. Conclusions: The GAPSP is a suitable, low-cost method for monitoring pencil beam scanning proton therapy, especially for non-spot scanning or additional collimation. The GAPSP can also estimate the treatment beam by the energy layer, a feature not common to other proton dosimetry tools.

Original languageEnglish
Pages (from-to)181-186
Number of pages6
JournalPhysica Medica
Publication statusPublished - 2020 Sept

Bibliographical note

Funding Information:
This work was supported by the Basic Science Research Programs through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (NRF-2016R1D1A1B04932909).

Publisher Copyright:
© 2020 Associazione Italiana di Fisica Medica


  • Dose monitoring
  • Pencil beam scanning proton therapy
  • Plastic scintillating plate
  • Treatment beam verification

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging
  • General Physics and Astronomy


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