Dosimetric impact of placement errors in optically stimulated luminescent in vivo dosimetry in radiotherapy

Tariq, Mahin; Gomez, Cindy; Riegel, Adam C.

doi:10.1016/j.phro.2019.08.004

Cited by 14 publications

(10 citation statements)

References 21 publications

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“…By combining entrance with exit measurements, differences in patient anatomy between planning and delivery can also be detected [24] . However, the transition from simple conformal fields to intensity-modulated techniques such as intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) has limited the usefulness of point measurements [25] , [26] , particularly when bearing in mind the additional uncertainty due to placement error, which can substantially impact measured-to-planned dose agreement of point detectors in high gradient regions, demonstrating the criticality of accurate dosimeter placement for IMRT and VMAT treatments [27] .…”

Section: Current Ivd Methodsmentioning

confidence: 99%

In vivo dosimetry in external beam photon radiotherapy: Requirements and future directions for research, development, and clinical practice

Olaciregui-Ruiz

Beddar

Greer

et al. 2020

Physics and Imaging in Radiation Oncology

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External beam radiotherapy with photon beams is a highly accurate treatment modality, but requires extensive quality assurance programs to confirm that radiation therapy will be or was administered appropriately. In vivo dosimetry (IVD) is an essential element of modern radiation therapy because it provides the ability to catch treatment delivery errors, assist in treatment adaptation, and record the actual dose delivered to the patient. However, for various reasons, its clinical implementation has been slow and limited. The purpose of this report is to stimulate the wider use of IVD for external beam radiotherapy, and in particular of systems using electronic portal imaging devices (EPIDs). After documenting the current IVD methods, this report provides detailed software, hardware and system requirements for in vivo EPID dosimetry systems in order to help in bridging the current vendor-user gap. The report also outlines directions for further development and research. In vivo EPID dosimetry vendors, in collaboration with users across multiple institutions, are requested to improve the understanding and reduce the uncertainties of the system and to help in the determination of optimal action limits for error detection. Finally, the report recommends that automation of all aspects of IVD is needed to help facilitate clinical adoption, including automation of image acquisition, analysis, result interpretation, and reporting/documentation. With the guidance of this report, it is hoped that widespread clinical use of IVD will be significantly accelerated.

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Section: Current Ivd Methodsmentioning

confidence: 99%

In vivo dosimetry in external beam photon radiotherapy: Requirements and future directions for research, development, and clinical practice

Olaciregui-Ruiz

Beddar

Greer

et al. 2020

Physics and Imaging in Radiation Oncology

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“…However, as the clinical reports show, patient entrance doses obtained for the IVD of complex RT techniques vary significantly due to the chip’s placement errors. As a result, the dosimetric uncertainty can be even doubled [ 4 ]. Therefore, one of the solutions to avoid dose discrepancies is to migrate from point-based in vivo dosimetry to planar or volumetric methods, enabling spatial dose measurements.…”

Section: Introductionmentioning

confidence: 99%

3D Dosimetry Based on LiMgPO4 OSL Silicone Foils: Facilitating the Verification of Eye-Ball Cancer Proton Radiotherapy

Sądel

Gajewski

Sowa

et al. 2021

Sensors

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A direct verification of the three-dimensional (3D) proton clinical treatment plan prepared for tumor in the eyeball, using the Eclipse Ocular Proton Planning system (by Varian Medical Systems), has been presented. To achieve this, a prototype of the innovative two-dimensional (2D) circular silicone foils, made of a polymer with the embedded optically stimulated luminescence (OSL) material in powder form (LiMgPO4), and a self-developed optical imaging system, consisting of an illuminating light source and a high-sensitive CCD camera has been applied. A specially designed lifelike eyeball phantom has been used, constructed from 40 flat sheet LMP-based silicone foils stacked and placed together behind a spherical phantom made by polystyrene, all to reflect the curvature of the real eyeball. Two-dimensional OSL signals were captured and further analyzed from each single silicone foil after irradiation using a dedicated patient collimator and a 58.8 MeV modulated proton beam. The reconstructed 3D proton depth dose distribution matches very well with the clinical treatment plan, allowing for the consideration of the new OSL system for further 3D dosimetry applications within the proton radiotherapy area.

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“…Accurate measurement of small radiation fields is a well-known challenge, due to loss in charged particle equilibrium. The potential of Al 2 O 3 :C point detectors for small field dosimetry was successfully accessed by many authors [30] , [31] . Several works demonstrated that plastic scintillators measured higher output factors than an ionization chamber, silicon diode and/or radiographic film [32] , due to difficulties to correct for the Cherenkov radiation and the differences in the active volumes of the detectors.…”

Section: Discussionmentioning

confidence: 99%

“…When we integrated a sequence of 10 images (resulting in a 200 ms integrated image), the signal-to-noise ratio improved and the difference observed in the valleys were 2–3%, with FHWM = 5.5 ± 0.2 mm. It is possible that part of the overresponse observed in the valley region were due to the films material’s specific energy dependency for energies below 100 keV [30] , [36] .…”

Section: Discussionmentioning

confidence: 99%

Two-dimensional real-time quality assurance dosimetry system using μ-Al2O3:C,Mg radioluminescence films

Nascimento

Verellen

Goossens

et al. 2020

Physics and Imaging in Radiation Oncology

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Background and purpose: There is a continual need for more accurate and effective dosimetric systems for quality assurance (QA) as radiotherapy evolves in complexity. The purpose of this project was to introduce a new system that minimally perturbs the main beam, while assessing its real time 2D dose-rate and field shapes. The system combined reusability, linear dose-rate response, and high spatial and time resolution in a single radiation detection technology that can be applied to surface dose estimation and QA. Materials and methods: We developed a 2D prototype system consisting of a camera, focusing lenses and short pass filter, placed on the head of a linear accelerator, facing an Al 2 O 3 :C,Mg radioluminescent film. To check the appropriateness of multi-leaf collimator, stability/reproducibility QA tests were prepared using the treatment planning system: including the routinely used alternating leaves, chair and pyramid checks. Results: The Al 2 O 3 :C,Mg film did not perturb the dose vs. depth dose curves determined with a point detector (-0.5% difference). Our results showed a dose-rate linear film response (R 2 = 0.999), from 5 to 600 MU/min. Measured output factors agreed with reference data within ~1%, indicating a potential for small field dosimetry. Both chair and pyramid measured profiles were comparable with those obtained with the treatment planning system within 1%. The alternating leaves test showed an average discrepancy in the valleys of 14%. Conclusions: The prototype demonstrated promising results. It obviated the need for corrections regarding the relative position of the camera, confirming accurate dose-rate delivery and detection of radiation fields.

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Dosimetric impact of placement errors in optically stimulated luminescent in vivo dosimetry in radiotherapy

Cited by 14 publications

References 21 publications

In vivo dosimetry in external beam photon radiotherapy: Requirements and future directions for research, development, and clinical practice

In vivo dosimetry in external beam photon radiotherapy: Requirements and future directions for research, development, and clinical practice

3D Dosimetry Based on LiMgPO4 OSL Silicone Foils: Facilitating the Verification of Eye-Ball Cancer Proton Radiotherapy

Two-dimensional real-time quality assurance dosimetry system using μ-Al2O3:C,Mg radioluminescence films

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