Feasibility Study on Applying Radiophotoluminescent Glass Dosimeters for CyberKnife SRS Dose Verification

Abstract

CyberKnife is one of multiple modalities for stereotactic radiosurgery (SRS). Due to the nature of CyberKnife and the characteristics of SRS, dose evaluation of the CyberKnife procedure is critical. A radiophotoluminescent glass dosimeter was used to verify the dose accuracy for the CyberKnife procedure and validate a viable dose verification system for CyberKnife treatment. A radiophotoluminescent glass dosimeter, thermoluminescent dosimeter, and Kodak EDR2 film were used to measure the lateral dose profile and percent depth dose of CyberKnife. A Monte Carlo simulation for dose verification was performed using BEAMnrc to verify the measured results. This study also used a radiophotoluminescent glass dosimeter coupled with an anthropomorphic phantom to evaluate the accuracy of the dose given by CyberKnife. Measurements from the radiophotoluminescent glass dosimeter were compared with the results of a thermoluminescent dosimeter and EDR2 film, and the differences found were less than 5%. The radiophotoluminescent glass dosimeter has some advantages in terms of dose measurements over CyberKnife, such as repeatability, stability, and small effective size. These advantages make radiophotoluminescent glass dosimeters a potential candidate dosimeter for the CyberKnife procedure. This study concludes that radiophotoluminescent glass dosimeters are a promising and reliable dosimeter for CyberKnife dose verification with clinically acceptable accuracy within 5%.

Three-dimensional printer-generated patient-specific phantom for artificial in vivo dosimetry in radiotherapy quality assurance

“…As per our expectations, notable dose differences should have been obtained because this study employed PLA filament. However, the dose difference between the anthropomorphic head phantom and the 3D-printed phantom was almost within the measurement uncertainty for the RPL glass dosimeter [23,30]. A factor contributing to this result may be the low CT value in the infill region of the 3D-printed phantom, as discussed in the previous section.…”

“…In Japan, postal dose audits have been performed on radiation therapy units using RPL glass dosimeters since 2007 [29] and previous studies have employed RPL glass dosimeters for radiotherapy dose verification. Hus et al compared measurements from an RPL glass dosimeter with those from a thermoluminescent dosimeter and radiographic film, and found differences less than 5%, which is clinically acceptable accuracy [30]. Nakaguchi et al also reported that the accuracy of the RPL glass dosimeter measurement was almost 5% and that angular dependency and geometric uncertainties should be considered [23].…”