Experimental determination of the photon-energy dependent dose-to-water response of TLD600 and TLD700 (LiF:Mg,Ti) thermoluminescence detectors

Schwahofer, A.; Feist, H.; Georg, Holger; Häring, Peter; Schlegel, Wolfgang

doi:10.1016/j.zemedi.2016.02.003

Cited by 7 publications

(12 citation statements)

References 20 publications

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“…TLD100 contains the natural abundance of 6 Li and 7 Li, while TLD600 contains primarily 6 Li. According to Schwahofer et al., TLD600 and TLD100 show the same response to photon radiation since the number of neutrons in Li does not affect the energy bands of the TLD crystal. For the same reason, it was assumed in this manuscript that there is no difference in the response with photon radiation energy of TLD100H and TLD700H.…”

Section: Methodsmentioning

confidence: 99%

“…The in‐ and out‐of‐field photon dose of the 6 MV treatments and the CBCT were measured separately using a combination of TLD100 and TLD100H chips. The two TLD types show a difference in response with photon radiation energy . If calibrated with 6 MV nominal beam energy, TLD100 show an over‐ and TLD100H an under‐response toward lower energy (down to 0.1 MeV) .…”

Section: Methodsmentioning

confidence: 99%

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Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Hauri

Schneider

2019

J Applied Clin Med Phys

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Purpose This study investigates the difference in whole‐body dose equivalent between 6 and 15 MV image‐guided radiotherapy (IGRT) for the treatment of a rhabdomyosarcoma in the prostate. Methods A previously developed model for stray radiation of the primary beam was improved and used to calculate the photon dose and photon energy in the out‐of‐field region for a radiotherapy patient. The dose calculated by the treatment planning system was fused with the model‐calculated out‐of‐field dose, resulting in a whole‐body photon dose distribution. The peripheral neutron dose equivalent was calculated using an analytical model from the literature. A daily cone beam CT dose was added to the neutron and photon dose equivalents. The calculated 3D dose distributions were compared to independent measurements conducted with thermoluminescence dosimeters and an anthropomorphic phantom. The dose contributions from the IGRT treatments of three different techniques applied with two nominal X‐ray energies were compared using dose equivalent volume histograms (DEVHs). Results The calculated and measured out‐of‐field whole‐body dose equivalents for the IGRT treatments agreed within (9 ± 10) % (mean and type A SD). The neutron dose equivalent was a minor contribution to the total out‐of‐field dose up to 50 cm from the isocenter. Further from the isocenter, head leakage was dominating inside the patient body, whereas the neutron dose equivalent contribution was important close to the surface. There were small differences between the whole‐body DEVHs of the 6 and 15 MV treatments applied with the same technique, although the single scatter contributions showed large differences. Independent of the beam energy, the out‐of‐field dose of the volumetric‐modulated arc therapy (VMAT) treatment was significantly lower than the dynamic intensity‐modulated radiation therapy (IMRT) treatment. Conclusion The calculated whole‐body dose helped to understand the importance of the dose contributions in different areas of the patient. Regarding radiation protection of the patient for IGRT treatments, the choice of beam energy is not important, whereas the treatment technique has a large influence on the out‐of‐field dose. If the patient is treated with intensity‐modulated beams, VMAT should be used instead of dynamic IMRT in terms of radiation protection of the patient. In general, the developed models for photon and neutron dose equivalent calculation can be used for any patient geometry, tumor location, and linear accelerator.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Hauri

Schneider

2019

J Applied Clin Med Phys

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“…The absorbed dose of the various treatment plans and the CBCT were measured separately with a combination of TLD100 and TLD100H chips. The two TLD types show a different response with radiation energy . Between 1 MeV and 0.1 MeV, TLD100 show an over‐ and TLD100H an under‐response.…”

Section: Methodsmentioning

confidence: 99%

“…The two TLD types show a different response with radiation energy. 15,16 Between 1 MeV and 0.1 MeV, TLD100 show an over-and TLD100H an under-response. For the dose measurements, a TLD100H chip was put on top of a TLD100 chip.…”

Section: C Tld Dose Measurementsmentioning

confidence: 99%

Technical Note: Comparison of peripheral patient dose from MR-guided ⁶⁰ Co therapy and 6 MV linear accelerator IGRT

2017

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“…A detailed description of the gel dose evaluation process is given in Mann et al 24 The TLDs were read-out using a hot gas reader (Harshow 5500, Thermofisher Scientific, USA) on the day of irradiation. The complete process of TLD reading is described in Schwahofer et al 22…”

Section: Dose Evaluationmentioning

confidence: 99%

Technical Note: On the feasibility of performing dosimetry in target and organ at risk using polymer dosimetry gel and thermoluminescence detectors in an anthropomorphic, deformable, and multimodal pelvis phantom

et al. 2021

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Objective To assess the feasibility of performing dose measurements in the target (prostate) and an adjacent organ at risk (rectum) using polymer dosimetry gel and thermoluminescence detectors (TLDs) in an anthropomorphic, deformable, and multimodal pelvis phantom (ADAM PETer). Methods The 3D printed prostate organ surrogate of the ADAM PETer phantom was filled with polymer dosimetry gel. Nine TLD600 (LiF:Mg,Ti) were installed in 3 × 3 rows on a specifically designed 3D‐printed TLD holder. The TLD holder was inserted into the rectum at the level of the prostate and fixed by a partially inflated endorectal balloon. Computed tomography (CT) images were taken and treatment planning was performed. A prescribed dose of 4.5 Gy was delivered to the planning target volume (PTV). The doses measured by the dosimetry gel in the prostate and the TLDs in the rectum (“measured dose”) were compared to the doses calculated by the treatment planning system (“planned dose”) on a voxel‐by‐voxel basis. Results In the prostate organ surrogate, the 3D‐γ‐index was 97.7% for the 3% dose difference and 3 mm distance to agreement criterium. In the center of the prostate organ surrogate, measured and planned doses showed only minor deviations (<0.1 Gy, corresponding to a percentage error of 2.22%). On the edges of the prostate, slight differences between planned and measured doses were detected with a maximum deviation of 0.24 Gy, corresponding to 5.3% of the prescribed dose. The difference between planned and measured doses in the TLDs was on average 0.08 Gy (range: 0.02–0.21 Gy), corresponding to 1.78% of the prescribed dose (range: 0.44%–4.67%). Conclusions The present study demonstrates the feasibility of using polymer dosimetry gel and TLDs for 3D and 1D dose measurements in the prostate and the rectum organ surrogates in an anthropomorphic, deformable and multimodal phantom. The described methodology might offer new perspectives for end‐to‐end tests in image‐guided adaptive radiotherapy workflows.

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Experimental determination of the photon-energy dependent dose-to-water response of TLD600 and TLD700 (LiF:Mg,Ti) thermoluminescence detectors

Cited by 7 publications

References 20 publications

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Technical Note: Comparison of peripheral patient dose from MR-guided ⁶⁰ Co therapy and 6 MV linear accelerator IGRT

Technical Note: On the feasibility of performing dosimetry in target and organ at risk using polymer dosimetry gel and thermoluminescence detectors in an anthropomorphic, deformable, and multimodal pelvis phantom

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Experimental determination of the photon-energy dependent dose-to-water response of TLD600 and TLD700 (LiF:Mg,Ti) thermoluminescence detectors

Cited by 7 publications

References 20 publications

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Whole‐body dose equivalent including neutrons is similar for 6 MV and 15 MV IMRT, VMAT, and 3D conformal radiotherapy

Technical Note: Comparison of peripheral patient dose from MR-guided 60 Co therapy and 6 MV linear accelerator IGRT

Technical Note: On the feasibility of performing dosimetry in target and organ at risk using polymer dosimetry gel and thermoluminescence detectors in an anthropomorphic, deformable, and multimodal pelvis phantom

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Product

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Technical Note: Comparison of peripheral patient dose from MR-guided ⁶⁰ Co therapy and 6 MV linear accelerator IGRT