A feasibility study of novel plastic scintillation dosimetry with pulse-counting mode

Abstract

The purpose of this study was to develop a novel scintillation dosimeter for in vivo dosimetry in Ir-192 brachytherapy via the pulse-counting mode. The new dosimeter was made from a plastic scintillator shaped into a hemisphere of diameter 1 mm and connected to the tip of a plastic optical fiber. The relationship between pulse counts and absorbed dose was derived based on the assumption that scintillation photons from the incident gamma ray are proportional to the absorbed dose. An equation for the conversion of pulse counts to water-equivalent dose was deduced wherein the pulse height spectrum from scintillation photons was assumed to be exponential. To confirm its accuracy, the dose rate distribution in a water phantom was measured by the present dosimeter and this was compared with Monte Carlo simulations, resulting in a discrepancy of less than 1.97%. It was found that the dosimeter has a wide dynamic range of linearity up to an order of magnitude of almost 10(3), including corrections for loss of counts due to pile-up.

Time‐resolved in vivo luminescence dosimetry for online error detection in pulsed dose‐rate brachytherapy

“…Furthermore, PDR brachytherapy typically requires an overall treatment time of 10-50 h per fraction, and most of the treatment is therefore carried out automatically without direct presence of hospital personnel neither in the brachytherapy control room nor with the patient. Online in vivo dosimetry in brachytherapy can be carried out using, for example, semiconductor detectors 15,16,[19][20][21][22] and fiber-coupled luminescence detectors based on organic scintillators, [23][24][25][26][27] aluminum oxide crystals, 28,29 or other materials. 30,31 A concern with the fiber-coupled dosimetry systems could be that optical fiber cables are difficult to handle in a clinical environment since they have a critical bending radius and should preferably not be subject to pulls or mechanical stress.…”

Development of a wavelength-separated type scintillator with optical fiber (SOF) dosimeter to compensate for the Cerenkov radiation effect

“…Figure 1 shows the components of our scintillation dosimetry system reported previously [ 10 ]. In the succeeding discussion, we refer to this dosimeter as the scintillator with optical fiber (SOF) dosimeter.…”

“…The pulse counts are transmitted to a personal computer via a universal serial bus (USB) connection. The measurable range of the SOF dosimeter, which is from 11.4 cGy min −1 to 1.15 × 10 4 cGy min −1 , covers a range of almost 10 3 cGy min −1 without switching measurement range [ 10 ].

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Real‐time in vivo dosimetry system based on an optical fiber‐coupled microsized photostimulable phosphor for stereotactic body radiation therapy

“…However, PSDs utilize radioluminescence (RL) signals and are therefore strongly affected by the stem signals generated in the optical fiber. Various countermeasures [21][22][23][24][25][26] against stem signals have been developed, but the effects of these signals cannot be completely eliminated. Even in the spectral, or chromatic, method [27][28][29][30][31] that is considered to be preferable, the measurement precision may deteriorate depending on the conditions of the calibration performed in advance.…”