Feasibility of using glass-bead thermoluminescent dosimeters for radiotherapy treatment plan verification

Jordan, Thomas; Distefano, G.; Bradley, D.A.; Spyrou, N. M.; Nisbet, Andrew; Clark, Catharine H.

doi:10.1259/bjr.20140804

Cited by 16 publications

(11 citation statements)

References 14 publications

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“…3, the positive value of mean percentage differences may suggest that, like other silicon based detectors [27,28] the silica beads slightly over respond (0.6% on average compared to alanine in this study). This was also noticed in previous work, [16,17]. However, all the values are within measurement uncertainty and so it is not possible to form a firm conclusion.…”

Section: Discussionsupporting

confidence: 52%

“…This beam quality was chosen as all radiotherapy centres employed 6 MV photon beams for their respective audit plans. A detailed description of the calibration procedure has been published previously [17].…”

Section: Silica Beads Calibrationmentioning

confidence: 99%

“…Silica beads have previously been characterised as novel high spatial resolution micro TLDs [14,15,16,17,18]. The particular silica beads employed have several potentially favourable physical characteristics as dosimeters in postal dosimetry audit of advanced radiotherapy.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility study of silica bead thermoluminescence detectors (TLDs) in an external radiotherapy dosimetry audit programme

Distefano

Lee

Gouldstone

et al. 2017

Radiation Physics and Chemistry

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Section: Discussionsupporting

confidence: 52%

Section: Silica Beads Calibrationmentioning

confidence: 99%

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Feasibility study of silica bead thermoluminescence detectors (TLDs) in an external radiotherapy dosimetry audit programme

Distefano

Lee

Gouldstone

et al. 2017

Radiation Physics and Chemistry

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“…More investigation might be helpful to provide better understanding of the behavior of the phantom under different clinical conditions. Although the bead TLD responses were assessed already in external RT by Jafari et al [15,16,17,34], it could be better to execute an external RT plan on this phantom within the presence of the silica beads.…”

Section: Discussionmentioning

confidence: 99%

“…A batch of 500 micro-silica beads (TrueInvivo Ltd., UK), 1.5 ±0.1 mm in diameter, 1.0 ±0.1 mm in thickness, and 3.7 ±0.1 mg in weight, with material composition (by weight), including C – 8.93%, O – 42.18%, Na – 10.55%, Al – 1.3%, Si – 33.62%, K – 1.09%, Ca – 1.92%, and Fe – 0.37%, was employed for this study. These dosimeters were selected for the dosimetry because of several of characteristics, such as small size, with a chemically inert nature, inexpensive, easy to use and reusable, with a fading rate of 10% at 30 days after irradiation and high thermoluminescence (TL) light transparency, high sensitivity, and a large dynamic dose range that remains linear ( R 2 ≥ 0.999) from 1 cGy to 25 Gy [ 15 , 16 , 17 , 18 ].…”

Section: Methodsmentioning

confidence: 99%

Development of a novel and low-cost anthropomorphic pelvis phantom for 3D dosimetry in radiotherapy

Babaloui¹,

Polak²,

Ghorbani³

et al. 2020

jcb

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Purpose The aim of this study was to construct a low-cost, anthropomorphic, and 3D-printed pelvis phantom and evaluate the feasibility of its use to perform 3D dosimetry with commercially available bead thermoluminescent dosimeters (TLDs). Material and methods A novel anthropomorphic female phantom was developed with all relevant pelvic organs to position the bead TLDs. Organs were 3D-printed using acrylonitrile butadiene styrene. Phantom components were confirmed to have mass density and computed tomography (CT) numbers similar to relevant tissues. To find out clinically required spatial resolution of beads to cause no perturbation effect, TLDs were positioned with 2.5, 5, and 7.5 mm spacing on the surface of syringe. After taking a CT scan and creating a 4-field conformal radiotherapy plan, 3 dose planes were extracted from the treatment planning system (TPS) at different depths. By using a 2D-gamma analysis, the TPS reports were compared with and without the presence of beads. Moreover, the bead TLDs were placed on the organs’ surfaces of the pelvis phantom and exposed to high-dose-rate (HDR) 60 Co source. TLDs’ readouts were compared with the TPS calculated doses, and dose surface histograms (DSHs) of organs were plotted. Results 3D-printed phantom organs agreed well with body tissues regarding both their design and radiation properties. Furthermore, the 2D-gamma analysis on the syringe showed more than 99% points passed 3%- and 3-mm criteria at different depths. By calculating the integral dose of DSHs, the percentage differences were –1.5%, 2%, 5%, and 10% for uterus, rectum, bladder, and sigmoid, respectively. Also, combined standard uncertainty was estimated as 3.5% ( k = 1). Conclusions A customized pelvis phantom was successfully built and assessed to confirm properties similar to body tissues. Additionally, no significant perturbation effect with different bead resolutions was presented by the external TPS, with 0.1 mm dose grid resolution.

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3D in vivo dosimetry of HDR gynecological brachytherapy using micro silica bead TLDs

Jaberi

Babaloui

Siavashpour

et al. 2022

J Applied Clin Med Phys

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This study aimed to evaluate the feasibility of defining an in vivo dosimetry (IVD) protocol as a patient-specific quality assurance (PSQA) using the bead thermoluminescent dosimeters (TLDs) for point and 3D IVD during brachytherapy (BT) of gynecological (GYN) cancer using 60 Co high-dose-rate (HDR) source. Methods: The 3D in vivo absorbed dose verification within the rectum and bladder as organs-at-risk was performed by bead TLDs for 30 GYN cancer patients. For rectal wall dosimetry, 80 TLDs were placed in axial arrangements around a rectal tube covered with a layer of gel. Ten beads were placed inside the Foley catheter to get the bladder-absorbed dose. Beads TLDs were localized and defined as control points in the treatment planning system (TPS) using CT images of the patients. Patients were planned and treated using the routine BT protocol. The experimentally obtained absorbed dose map of the rectal wall and the point dose of the bladder were compared to the TPSs predicted absorbed dose at these control points. Results: Relative difference between TPS and TLDs results were −8.3% ± 19.5% and −7.2% ± 14.6% (1SD) for rectum-and bladder-absorbed dose, respectively.Gamma analysis was used to compare the calculated with the measured absorbed dose maps. Mean gamma passing rates of 84.1%, 90.8%, and 92.5% using the criteria of 3%/2 mm, 3%/3 mm, and 4%/2 mm were obtained, respectively. Eventually, a "considering level" of at least 85% as pass rate with 4%/2-mm criteria was recommended. Conclusions: A 3D IVD protocol employing bead TLDs was presented to measure absorbed doses delivered to the rectum and bladder during GYN HDR-BT as a reliable PSQA method. 3D rectal absorbed dose measurements were performed. Differences between experimentally measured and planned absorbed dose maps were presented in the form of a gamma index, which may be used as a warning for corrective action.

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Feasibility of using glass-bead thermoluminescent dosimeters for radiotherapy treatment plan verification

Abstract: Commercial glass beads are utilized as low-cost novel TLDs for treatment-plan verification.

Cited by 16 publications

References 14 publications

Feasibility study of silica bead thermoluminescence detectors (TLDs) in an external radiotherapy dosimetry audit programme

Feasibility study of silica bead thermoluminescence detectors (TLDs) in an external radiotherapy dosimetry audit programme

Development of a novel and low-cost anthropomorphic pelvis phantom for 3D dosimetry in radiotherapy

3D in vivo dosimetry of HDR gynecological brachytherapy using micro silica bead TLDs

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