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

Distefano, G.; Lee, J; Gouldstone, C.; Mayles, Helen; Jupp, T; Nisbet, Andrew; Clark, Catharine H.

doi:10.1016/j.radphyschem.2017.07.021

Cited by 9 publications

(3 citation statements)

References 27 publications

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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%

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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Section: Discussionmentioning

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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“…Micro silica bead TLDs, which were discovered in 2014 as novel radiation detectors, exhibit several favorable characteristics; they have a small size and chemically inert nature, are inexpensive, are reusable, have a fading rate of 10% at 30 days after irradiation, high thermoluminescence (TL) light transparency, and an extensive dynamic dose-response range that remains linear (R 2 ≥ 0.999) from 1 cGy to 25 Gy. [15][16][17][18][19] Some common TLDs types, such as lithium fluoride (LiF) and dysprosium-doped calcium sulfate (CaSO 4 :Dy) ones, can only measure absorbed doses of up to 10 Gy 20 or possess a 28-day fading rate of 25%-60%. 21 In addition, the spherical shape of the bead TLDs with a hole in the middle enables them to arrange in 2D and 3D configurations.…”

Section: Introductionmentioning

confidence: 99%

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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“…In recent years other than TLD-100, various types of transfer detector have also been introduced in postal dosimetry audits, including RPL (radio-photoluminescence) glass dosimeters (Mizuno et al, 2014;Okamoto et al, 2018), optically stimulated luminescent (OSL) dosimeters (Alvarez et al, 2017;Lye et al, 2014), radio-chromic film (Okamoto et al, 2018) and alanine dosimeters (McEwen et al, 2015;Yamaguchi et al, 2020). A number of workers have examined the feasibility of use of more novel high spatial resolution TLDs, including silica beads for lung radiotherapy postal dosimetry audits (Jafari et al, 2017) and Ge-doped optical fibres for high energy photon beam audits (Fadzil et al, 2014;Noor et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Dosimetric characteristics of fabricated germanium doped optical fibres for a postal audit of therapy electron beams

Abdullah

Bradley²,

Nisbet³

et al. 2022

Radiation Physics and Chemistry

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

Cited by 9 publications

References 27 publications

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

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

Dosimetric characteristics of fabricated germanium doped optical fibres for a postal audit of therapy electron beams

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