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

Abstract

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.

End-to-End QA in Radiation Therapy Quality Management

“…If the delivery under evaluation involves motion management, then the phantom will have to be able to be integrated into some commercial or in-house built motion testing system [129,130,178,179]. For some RT deliveries the E2E QA phantoms may need to be more anthropomorphic in external appearance (e.g., if the delivery requires phantom set-up in some patient immobilization system with set-up validation and repositioning) or to simulate internal structure heterogeneity with organ mimicking structures (e.g., if the E2E testing is being applied to RT delivery to specific anatomy and the assessment includes target conformity) [89,102,104,106,111,180,181]. The material for the phantom need not be exactly tissue or water equivalent although it should be similar to any organs of interest and should be well characterised by CT, and perhaps MR imaging, before use [174].…”

End-to-end test for fractionated online adaptive MR-guided radiotherapy using a deformable anthropomorphic pelvis phantom

“…The experiment was carried out using the so-called ADAM-PETer (Anthropomorphic, Deformable And Multimodal pelvis phantom with positron emission tomography (PET) Extension for Radiotherapy), which was initially designed to perform a variety of different end-to-end tests in radiotherapy (Gillmann et al 2021, Marot et al 2021. In the present study, however, no PET measurements were performed and the included lymph node system was not used.…”

“…Other studies have suggested the use of thermoluminescence detectors (TLDs) to renormalize the absolute PG dose distribution (Mann et al 2019, Schwahofer et al 2020 as well as to combine PG and TLDs for dose measurements within the updated version of the ADAM phantom (ADAM-PETer, Marot et al (2021)). Marot et al (2021) applied the same phantom as used in the present study equipped with a PG-filled prostate and TLDs in the rectum. However, the phantom was used only statically without employing MR-guidance or online adaption of the treatment plan.…”

Thermoluminescent Tb(III) and Dy(III) complexes with redox‐active ligands: experimental and theoretical study

“…Whereas the luminescence properties of inorganic rare‐earths compounds have been widely studied, [ 17–21 ] there is practically no information on the TL of lanthanide coordination compounds, although there is available information on TL in organic compounds, as well as in polymers. [ 22–25 ]…”

“…Whereas the luminescence properties of inorganic rare-earths compounds have been widely studied, [17][18][19][20][21] there is practically no information on the TL of lanthanide coordination compounds, although there is available information on TL in organic compounds, as well as in polymers. [22][23][24][25] Previously, we obtained interesting coordination compounds of terbium and dysprosium, which are able to store the energy from ultraviolet (UV) and X-ray radiation. [26,27] The energy from UV and X-ray radiation stored by these materials can be stored indefinitely at a low temperature even if the external excitation is removed.…”