Evaluation of nanoDot optically stimulated luminescence dosimeter for cone-shaped small-field dosimetry of cyberknife stereotactic radiosurgery unit: A monte carlo simulation and dosimetric verification study

Abstract

Aim: The aim of this study was to investigate the adequacy of nanoDot optically stimulated luminescence (OSL) dosimeter for small field dosimetry before its in vivo applications in CyberKnife SRS unit. Materials and Methods: A PTW 60018 SRS Diode, 60019 microDiamond, and Gafchromic EBT3 films were used along with a nanoDot carbon-doped aluminum oxide OSL dosimeter to collect and compare beam data. In addition, the EGSnrc/BEAMnrc code was employed to simulate 6-MV photon beams of CyberKnife SRS system. Results: All detectors showed good consistency with each other in output factor measurements for cone sizes of 15 mm or more. The differences were maintained within 3% for these cones. However, OSL output factors showed higher discrepancies compared to those of other detectors for smaller cones wherein the difference reached nearly 40% for cone size of 5 mm. Depending on the performance of OSL dosimeter in terms of output factors, percentage depth doses (PDDs) were only measured for cones equal to or larger than 15 mm. The differences in PDD measurements were within 5% for depths in the range of 5–200 mm. Conclusion: Its low reliable readings for cones smaller than 15 mm should be considered before its in vivo applications of Cyberknife system.

Determination of inflection points of CyberKnife dose profiles within acceptability criteria of deviations in measurements

“…The water-equivalent window thickness of the microdiamond is smaller; however, the difference between their correction factors we obtained for another study was not significant. 14 In this work, measured values for field sizes were the same except for the 15 mm cone. For the smallest cone, there is a direction of difference between these two evaluations.…”

“…The MC simulation was validated through percentage depth dose (PDD) and output factors measurements and results were published elsewhere. 14 For MC dose profiles the water phantom was modelled as 30 cm × 30 cm × 30 cm using different voxel sizes, 1 mm for all cone sizes except 60 mm cone for which it was 5 mm. The dose profile computation was at the depth of 5 cm with SAD of 80 cm.…”

Investigation of pediatric backscatter factor with an anthropomorphic phantom

“…It boasts a lower detection limit of 0.1 mGy and an accuracy of 10% in energy dependence within the diagnostic energy range of 70 kVp to 140 kVp, and standard accuracy within 10%. In addition, experimental data have revealed 40-50 times greater sensitivity for OSLDs compared with TLDs [20][21][22].…”

Measurement of the whole body, eye lens and extremity occupational exposures in nuclear medicine staff at King Chulalongkorn Memorial Hospital

“…Currently, OSLD is commercially available by Nagase Landauer, Tsukuba, Ibaraki, Japan, and widely used in various studies, including environmental, personnel dosimeter, and patients dose measurements in both therapeutic and diagnostic radiology (17)(18)(19).…”