Dosimetric properties of a commercial PTW 60019 synthetic diamond detector in small photon fields

• 作 者: ChangXue WangKun ZhangJian WangZhipeng JinSunjun
• 机 构: NationalInstituteofMetrology,Beijing100027,China,NationalInstituteofMetrology,Beijing100027,China,Na
• 出 处: 中华放射医学与防护杂志
• 发表日期: 2018年38期
• 关键词: Small field Synthetic diamond detector Relative dose

Objective

To investigate the dosimetric properties of PTW 60019 synthetic diamond detector in small photon beams.

Methods

A PTW 60019 synthetic diamond detector was tested under 6 and 10 MV photon beams, respectively. Linearity with dose, dose rate dependence and off-axis ratio were measured and compared to those measured by an IBA SFD. Percentage depth doses were measured and compared to those measured by an IBA SFD and a PTW 31010 semiflex chamber. Total scatter factors were measured and compared to those measured by an IBA SFD and a PTW 31016 PinPoint chamber.

Results

The dose response of a PTW 60019 synthetic diamond detector showed a good linear behavior as a function of dose, with observed deviations below 0.2% over a dose range from 100 to 1 000 MU. The dose rate response was almost independent, with deviations below 0.2% in the dose rate range from 37 to 614 MU/min. For the fields of 20－100 mm in diameter, there were dose differences in percentage depth doses within 1% as compared to an IBA SFD and a PTW 31010 semiflex chamber. For the 10 mm diameter field, the differences were up to 5.8% in the build-up region. Off-axis ratios measurements showed a good agreement among the involved detectors (<1%). The higher differences appeared in the penumbra region. A good agreement was also found in terms of total scatter factor measurements for the related detectors.

Conclusions

The observed dosimetric properties of the PTW 60019 synthetic diamond detector indicate that it is a suitable candidate for small photon beam dosimetry.