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Dosimetry - Europe PMC

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Last Updated: 03 August 2022

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The probe-format graphite calorimeter, Aerrow, for absolute dosimetry in ultra-high pulse dose rate electron beams.

Methods The calorimeter system is used to determine the potential effect of dose per pulses delivered up to 5. 6 Gy, the number of pulses delivered per measurement, and the potential for relative measurement are all used in this paper. The finite element method was used to determine heat transfer corrections along the percentage depth dose of a 20 MeV electron beam, according to the percentage depth dose. Dose conversion factors that were used to determine absorbed dose to-water are also shown in Monte Carlo. Conclusion in this study It was discovered that in a UHPDR electron beam, the Aerrow probe-type graphite calorimeter can be used for relative and absolute dosimetry in water. This is the first reported use of an absorbed dose calorimeter for an in-water percentage depth curve analysis, according to the author.

Source link: https://europepmc.org/article/MED/35912973


Factors modulating 99m Tc-MAA planar lung dosimetry for 90 Y radioembolization.

Purpose To investigate the reliability and biases of predicted lung shunt fraction and lung dose estimations using 99 million Tc-aggregated albumin planar imaging for treatment planning of 90 Y-microsphere radioembolization. The reliability of each planar-based LSF and LD methods, which have been demonstrated in phantom and patient studies, was determined by determining the median absolute difference between SPECT/CT-based LSF and LD estimates, which have been used to more precisely and precisely determine the true LSF and LD values. Standard-of-care LSF using geometric mean of lung and liver contours had median absolute overestimation of 4. 4 percentage points from SPECT/CT LSF. LSF errors were only reduced when using anterior views. Conclusions: Planning calculator LSF from lung and liver contours of a single view and planar LD using the same LSF and 1000 g lung mass was found to increase precision and minimize bias in planar lung dosimetry.

Source link: https://europepmc.org/article/MED/35906892


Radiation quality correction factors for improved dosimetry in preclinical minibeam radiotherapy.

For preclinical x-ray and proton minibeams, their effect on dosimetric accuracy was determined using dosimetry calibration dosimetry calibration parameters for the PTW microdiamond. Methods A method for the determination of radiation quality correction factors for absolute dosimetry in minibeam fields was devised. Following our formalism, radiation quality correction factors for the PTW microDiamond detector were determined using the Monte Carlo method. In the following scenarios: reference dosimetry open field to minibeam center of the central peak, iii various positions on the minibeam profile along the peaks and valleys direction to the central minibeam's center; iii some representative depth positions. Conclusions The use of the PTW microdiamond detector in minibeam reference dosimetry requires radiation quality calibration factors.

Source link: https://europepmc.org/article/MED/35904962


Comparison of PMT-based TF64 and SiPM-based Vereos PET/CT systems for 90 Y imaging and dosimetry optimization: a quantitative study.

Background Selective internal radiotherapy based on transarterial radio-embolization with yttrium-90 microspheres is an established therapy for primary or metastatic liver disease. Methods NEMA 2012 PET phantom was packed with nearly 3. 9 GBq of 90 Y activity and collected on days 0, 3, 5, 7, and 9 on a classic Time-of-Flight PET/CT scanner and on a silicon photomultiplier based PET/CT scanner based on a Samsung X-Flight PET/CT scanner. The comparison of measured and true doses enabled us to identify the image containing the most consistent dose estimates and, in turn, specify the set of parameters to be used on patients' data for the reconstruction of optimized clinical images. The most accurate results for quantitative 90 Y measurements were produced by a SiPM-based PET/CT system, with reconstructed images with a 2-mm voxel size and the application of the point spread function correction.

Source link: https://europepmc.org/article/MED/35894818


Mitigating the uncertainty in small field dosimetry by leveraging machine learning strategies.

Small field dosimetry is significantly different from broad beam dosimetry due to a lack of electron side scatter equilibrium, source occlusion, and consequences related to the choice of detector. With the increase in evidences for intensity-modulated radiation therapy and stereotactic body radiation therapy, however, accurate dosimetry is becoming more important. Here we recommend that machine learning methods be used to reduce the risks and increase the accuracy in determining small field output factors. Incorporating these models into the dose estimation process could greatly improve the accuracy and robustness of dose estimation for any radiotherapy delivery method that depends heavily on small fields.

Source link: https://europepmc.org/article/MED/35803256


The fast calibration model for dosimetry with an electronic portal imaging device.

Purpose The aim of this research was to produce an algorithm that corrects the image of a linear accelerator's electronic portal imaging system so that it can be used for dosimetric or quality assurance for photon radiotherapy in vivo. The effect of the field size, phantom thickness, and the varying spectral photon distribution within the irradiation field on the EPID image was investigated for that purpose. To convert the EPID image to a dose delivery, an EPID calibration and correction scheme was developed. The results Within 0. 6 percent was shown by several correction factors. It was also possible to correct the influence of the field size, phantom thickness on the EPID signal, as well as homogenization of the image profile by several correction factors within 0. 6%. Conclusion The improved algorithm allows the EPID to be monitored online during the radiation therapy, which is included in the endnotes.

Source link: https://europepmc.org/article/MED/35876832


Inhalation Bioaccessibility and Risk Assessment of Metals in PM 2.5 Based on a Multiple-Path Particle Dosimetry Model in the Smelting District of Northeast China.

The bioavaibility of PM 2. 5 heavy metals and the deposition fraction must be addressed urgently in order to be consistent with the reality of the pulmonary area and avoid overestimating the danger of inhalation human health risk. According to the EPA's exposure determination tool, the inhalation exposure threshold was estimated, and the human health risk with different inhalation exposure doses was compared. U00b7kg-1 for the non-carcinogenic exposure dose, and 0. 04-14. 2 mg/u00b7kg -1 for the carcinogenic exposure dose. Cd and Pb in PM 2. 5 in the study area have a non-carcinogenic risk to human health, and Cd have no or a potential carcinogenic threat to human health. A new inhalation health risk assessment may avoid overestimation.

Source link: https://europepmc.org/article/MED/35897292


Personalized Dosimetry in the Context of Radioiodine Therapy for Differentiated Thyroid Cancer.

Differentiated Thyroid Cancer, which accounts for more than 90% of cases, is the most common thyroid disease. The systemic administration of 131-sodium or potassium iodide is a promising option for treating DTC. Due to its association with tissue irradiation reactions, the Absorbed dose is a reliable predictor of biological response. This review seeks to summarize new evidence for a dosimetry-based therapy and so explore new options that may lead to more tailored therapies, minimizing the risks of radioiodine therapy for Differentiated Thyroid Cancer's potential side effects.

Source link: https://europepmc.org/article/MED/35885666

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions

* Please keep in mind that all text is summarized by machine, we do not bear any responsibility, and you should always check original source before taking any actions