Progress in Medical Physics (한국의학물리학회지:의학물리)

Korean Society of Medical Physics (한국의학물리학회)
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Analysis of Small-Field Dosimetry with Various Detectors

  • Park, So-Yeon (Department of Radiation Oncology, Veterans Health Service Medical Center) ;
  • Choi, Byeong Geol (Department of Radiation Oncology, Veterans Health Service Medical Center) ;
  • Lee, Dong Myung (Department of Radiation Oncology, Veterans Health Service Medical Center) ;
  • Jang, Na Young (Department of Radiation Oncology, Veterans Health Service Medical Center)
  • Received : 2018.11.30
  • Accepted : 2018.12.14
  • Published : 2018.12.31
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Abstract

We evaluated the performance of various detectors for small-field dosimetry with field sizes defined by a high-definition (HD) multileaf collimator (MLC) system. For small-field dosimetry, diodes referred to as "RAZOR detectors," MOSFET detectors, and Gafchromic EBT3 films were used in this study. For field sizes less than $1{\times}1cm^2$, percent depth doses (PDDs) and lateral profiles were measured by diodes, MOSFET detectors, and films, and absolute dosimetry measurements were conducted with MOSFET detectors. For comparison purposes, the same measurements were carried out with a field size of $10{\times}10cm^2$. The dose distributions were calculated by the treatment planning system Eclipse. A comparison of the measurements with calculations yielded the percentage differences. With field sizes less than $1{\times}1cm^2$, it was shown that most of the percentage difference values were within 5% for 6-MV and 15-MV photon beams with the use of diodes. The measured lateral profiles were well matched with those calculated by Eclipse as the field sizes increased. Except for the depths of 0.5 cm and 20 cm, there was agreement in terms of the absolute dosimetry within 10% when MOSFET detectors were used. There was good agreement between the calculations and measurements conducted using diodes and EBT films. Both diode detectors and EBT3 films were found to be appropriate options for relative measurements of PDDs and for lateral profiles.

Keywords

References

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