Dosimetric properties of a commercial PTW 60019 synthetic diamond detector in small photon fields / 中华放射医学与防护杂志

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.

Determination of Fe, Co, Mn and Ni in Synthetic Diamonds by Inductively Coupled Plasma Atomic Emission Spectrometry / 分析化学

A method for the determination of Fe, Co, Mn and Ni in synthetic diamonds by inductively coupled plasma atomic emission spectrometry ( ICP-AES) was proposed. The synthetic diamond sample was decomposed completely, while the sample was burned in air at 1000 ℃ for 10 h, and then a mixed acid of H2 SO4 , aqua regia and HClO4 was used for the dissolving the residue of the sample. In this method, the limits of detection of Fe, Co, Mn and Ni were 0. 0147, 0. 0018, 0. 0006 and 0. 0027 mg/L, respectively. Under the optimum condition, Fe, Co, Mn and Ni in synthetic diamond sample were determined. The values of RSDs (n=7) were less than 0. 5%. The recoveries of added standard were 94. 0%-105. 0%.