Properties of a commercial PTW-60019 synthetic diamond detector for the dosimetry of small radiotherapy beams
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-01-07 |
| Journal | Physics in Medicine and Biology |
| Authors | JosĂ© M. LĂĄrragaâGutiĂ©rrez, Paola BallesterosâZebadĂșa, Miguel RodrĂguez-Ponce, Olivia Amanda GarcĂaâGarduño, O. O. GalvĂĄn de la Cruz |
| Institutions | Instituto Nacional de NeurologĂa y NeurocirugĂa, Instituto Nacional de CancerologĂa |
| Citations | 98 |
Abstract
Section titled âAbstractâA CVD based radiation detector has recently become commercially available from the manufacturer PTW-Freiburg (Germany). This detector has a sensitive volume of 0.004 mm(3), a nominal sensitivity of 1 nC Gy(-1) and operates at 0 V. Unlike natural diamond based detectors, the CVD diamond detector reports a low dose rate dependence. The dosimetric properties investigated in this work were dose rate, angular dependence and detector sensitivity and linearity. Also, percentage depth dose, off-axis dose profiles and total scatter ratios were measured and compared against equivalent measurements performed with a stereotactic diode. A Monte Carlo simulation was carried out to estimate the CVD small beam correction factors for a 6 MV photon beam. The small beam correction factors were compared with those obtained from stereotactic diode and ionization chambers in the same irradiation conditions The experimental measurements were performed in 6 and 15 MV photon beams with the following square field sizes: 10 Ă 10, 5 Ă 5, 4 Ă 4, 3 Ă 3, 2 Ă 2, 1.5 Ă 1.5, 1 Ă 1 and 0.5 Ă 0.5 cm. The CVD detector showed an excellent signal stability (<0.2%) and linearity, negligible dose rate dependence (<0.2%) and lower response angular dependence. The percentage depth dose and off-axis dose profiles measurements were comparable (within 1%) to the measurements performed with ionization chamber and diode in both conventional and small radiotherapy beams. For the 0.5 Ă 0.5 cm, the measurements performed with the CVD detector showed a partial volume effect for all the dosimetric quantities measured. The Monte Carlo simulation showed that the small beam correction factors were close to unity (within 1.0%) for field sizes â„1 cm. The synthetic diamond detector had high linearity, low angular and negligible dose rate dependence, and its response was energy independent within 1% for field sizes from 1.0 to 5.0 cm. This work provides new data showing the performance of the CVD detector compared against a high spatial resolution diode. It also presents a comparison of the CVD small beam correction factors with those of diode and ionization chamber for a 6 MV photon beam.