In vivo dosimeters for HDR brachytherapy: A comparison of a diamond detector, MOSFET, TLD, and scintillation detector

Abstract

The large dose gradients in brachytherapy necessitate a detector with a small active volume for accurate dosimetry. The dosimetric performance of a novel scintillation detector (BrachyFOD) is evaluated and compared to three commercially available detectors, a diamond detector, a MOSFET, and LiF TLDs. An 192Ir HDR brachytherapy source is used to measure the depth dependence, angular dependence, and temperature dependence of the detectors. Of the commercially available detectors, the diamond detector was found to be the most accurate, but has a large physical size. The TLDs cannot provide real time readings and have depth dependent sensitivity. The MOSFET used in this study was accurate to within 5% for distances of 20 to 50 mm from the 192Ir source in water but gave errors of 30%-40% for distances greater than 50 mm from the source. The BrachyFOD was found to be accurate to within 3% for distances of 10 to 100 mm from an HDR 192Ir brachytherapy source in water. It has an angular dependence of less than 2% and the background signal created by Cerenkov radiation and fluorescence of the plastic optical fiber is insignificant compared to the signal generated in the scintillator. Of the four detectors compared in this study the BrachyFOD has the most favorable combination of characteristics for dosimetry in HDR brachytherapy.

TRUS-probe integrated MOSkin detectors for rectal wall in vivo dosimetry in HDR brachytherapy: In phantom feasibility study

“…Moreover, if performed on-line, it allows the constant monitoring of the dose delivered during the treatment, enabling the immediate intervention of the clinician if adverse dose readings are detected (Lambert et al, 2007).…”

Inter-Fraction and Intra-Fraction Variation in the Absorbed-Dose Delivery during Interstitial High Dose Rate Brachytherapy—A Study Using MicroMOSFET <i>In-Vivo</i> Dosimeter

“…Lambert et al [7] for Brachytherapy. The intra-fraction and inter-fraction dose delivery uncertainties during Interstitial Brachytherapy using flexible catheters are measured and analyzed in this study.…”

Comparison of the New MOSkin Detector and Fiber Optic Dosimetry System for Radiotherapy

“…They can be made quite small, with 1 mm thick crystals now being common. Smaller 0.5 mm thick crystals are also available, which means fiber optic dosimeters offer a sensitive volume with a thickness comparable to or better than that of TLDs 1) . Their water equivalence is a valuable characteristic, as ion chambers introduce complicated issues related to the difference in the physical characteristics of the surrounding material, and that of the ion chamber.…”

“…The main issue with fiber optic dosimetry has always been the background radiation due to * Corresponding Author, Tel No: +61-2-4221-4574, Fax No: +61-2-4221-5944, E-Mail: anatoly@uow.edu.au ** B. Lee is currently a visiting fellow at CMRP on subbatical Cerenkov radiation. 1,2) Cerenkov radiation is produced when charged particles, (electrons in this case) pass through the fiber at a speed greater than the speed of light in the fiber. The Cerenkov radiation produced when a high energy photon beam is delivered from a linear accelerator (LINAC) has a wavelength in the 400-480 nm range, which is in the violet and blue end of the visible spectrum.…”