In vivo measurements for high dose rate brachytherapy with optically stimulated luminescent dosimeters

Abstract

OSLDs can be successfully used for HDR in vivo dosimetry. However, for the measurements to be meaningful one must account for the angular dependence, volume-averaging, and the greater sensitivity to Ir-192 gamma rays than to 6 MV x-rays if 6 MV x-rays were used for OSLD calibration. The limitations of the treatment planning algorithm must be understood, especially for surface dose measurements. Use of in vivo dosimetry for HDR brachytherapy treatments is feasible and has the potential to detect and prevent gross errors. In vivo HDR brachytherapy should be included as part of the QA for a HDR brachytherapy program.

Anthropomorphic phantom to investigate the bladder dose in gynecological high-dose-rate brachytherapy

“…A similar study related to the present work was performed by Sharma et al (27). In this work, the authors presented the use of commercial Nanodot dosimeters (Landauer, Inc., Glenwood, IL) for in vivo dosimetry measurements in patients being treated with HDR.…”

In vivo dosimetry and acute toxicity in breast cancer patients undergoing intraoperative radiotherapy as boost

“…Recently, OSLD has been widely used in measuring multiple radiation dose types, such as heavy ion beams, photons, electrons, and protons. Sharma and Jursinic [18] successfully used OSLD in surface dose measurement for high dose rate (HDR) brachytherapy with minimal uncertainty. The data acquired from in vivo dosimetry were useful in determining factors related to higher skin dose, which may increase the risk of acute and late skin reactions.…”

AAPM TG 191: Clinical use of luminescent dosimeters: TLDs and OSLDs

“…At lower energies, angular dependence has been found to increase for the nanoDot TM , although the results in the literature are not always consistent. A 4% angular dependence effect was observed for Ir‐192, and a 3%–16% effect in diagnostic CT beams (80–140 kV) . Angular variation of 40% at 80 kVp and of 70% in a mammography beam have also been reported.…”

“…That is, k Q varies as more material separates the source and detector. This effect was nearly 10% between 2 and 10 cm of solid water for 192 Ir . Additionally, the different filtration of different sources can also lead to different k Q factors: Nucletron and Varian Ir‐192 sources were found to have different energy responses by 2.6% .…”

“…Additionally, the different filtration of different sources can also lead to different k Q factors: Nucletron and Varian Ir‐192 sources were found to have different energy responses by 2.6% . An angular dependence of ~4% between edge‐on and en‐face irradiations of the nanoDot TM LD has been observed in 192 Ir because of asymmetric attenuation of the beam in the plastic casing and across the OSLD disk itself . As a final note, it has been observed that the sensitivity changes observed after large accumulated doses (>10 Gy) are not consistent between megavoltage energy and 192 Ir, further justifying the 10 Gy accumulated dose limit for nanoDot TM LDs.…”