Accuracy evaluation of distance inverse square law in determining virtual electron source location in Siemens Primus linac

Douk, Hamid Shafaei; Aghamiri, Mahmoud Reza; Ghorbani, Mahdi; Farhood, Bagher; Bakhshandeh, Mohsen; Hemmati, Hamid

doi:10.1016/j.rpor.2018.01.002

Cited by 8 publications

(4 citation statements)

References 9 publications

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“…The accuracy of the virtual source position for the calculation data can be used to validate the accuracy of the Monte Carlo modeling. 25 The reported data show a good agreement between the measured and the RayStation data validating the individual jaw and scraper positions of each applicator/energy of the RayStation model. The observed data show a trend of a minor overestimation of the distance of the virtual source position to the applicator surface in the RayStation model for the smallest applicator pointing out the necessity for the validation of small inserts at extended SSD before clinical implementation.…”

Section: Ssd Dependence Of Dose Outputsupporting

confidence: 67%

“…Electron beams are shaped by the scrapers in the electron applicators, 24 and for the Elekta accelerator, four different scraper levels are present gradually limiting electron field size that depends on each selected energy and applicator, 16 a configuration that is quite different compared to other linacs. The accuracy of the virtual source position for the calculation data can be used to validate the accuracy of the Monte Carlo modeling 25 . The reported data show a good agreement between the measured and the RayStation data validating the individual jaw and scraper positions of each applicator/energy of the RayStation model.…”

Section: Discussionmentioning

confidence: 67%

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Measurement‐based validation of a commercial Monte Carlo dose calculation algorithm for electron beams

et al. 2022

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Purpose This work presents the clinical validation of RayStation's electron Monte Carlo code by the use of diodes and plane parallel radiation detectors in homogenous and heterogeneous tissues. Results are evaluated against internationally accepted criteria. Methods The Monte Carlo–based electron beam dose calculation code was validated using diodes, air‐ and liquid‐filled parallel radiation detectors on an Elekta linac with beam energies of 4, 6, 8, 10, and 12 MeV. Treatment setups with varying source‐to‐skin distances, different applicators, various cutouts, and oblique beam incidences were addressed, together with dose prediction behind lung‐, air‐, and bone‐equivalent inserts. According to NCS (Netherlands Commission for Radiation Dosimetry) report 15 for nonstandard treatment setups, a dose agreement of 3% in the δ1 region (high‐dose region around Zref), a distance‐to‐agreement (DTA) of 3 mm or a dose agreement of 10% in the δ2 region (regions with high‐dose gradients), and 4% in the δ4 region (photon tail/low‐dose region) were applied. During validation, clinical routine settings of 2 × 2 × 2‐mm3 dose voxels and a statistically dose uncertainty of 0.6% (250 000 histories/cm2) were used. Results RayStation's electron Monte Carlo code dose prediction was able to achieve the tolerances of NCS report 15. Output predictions as a function of the SSD improve with energy and applicator size. Cutout data revealed no field size or energy dependence on the accuracy of the dose prediction. Excellent agreement for the oblique incidence data was achieved and a maximum of one voxel difference was obtained for the DTA behind heterogeneous inserts. Conclusions The accuracy of RayStation's Monte Carlo–based electron beam dose prediction for Elekta accelerators is confirmed for clinical treatment planning that is not only performed within an acceptable timeframe in terms of the number of histories but also addresses for homogenous and heterogeneous media.

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Section: Ssd Dependence Of Dose Outputsupporting

confidence: 67%

Section: Discussionmentioning

confidence: 67%

Measurement‐based validation of a commercial Monte Carlo dose calculation algorithm for electron beams

et al. 2022

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“…Notably, the latter two mechanisms-penetration and direct escape-are more common with higher-energy beams, while scattering is characteristic of lower-energy beams which includes scattered electrons and bremsstrahlung photons [8,24]. The energy spectrum of scattered photons and electrons depends on the eld size, distance from the applicator, and material of the applicator, which can be approximated using Monte Carlo simulations [7,25]. The main source of the peripheral dose is known to be the photons produced in the Bremsstrahlung effect [13].…”

Section: Discussionmentioning

confidence: 99%

Peripheral doses outside the electron applicators in an Elekta Versa HD Linac

Maharaj,

Goodall,

Sabet

et al. 2024

Preprint

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Background Radiotherapy is an essential component of cancer treatment, but healthy tissues can be exposed to out-of-field doses, potentially causing adverse effects and secondary cancers. This study investigates peripheral doses outside the electron beam applicator in an Elekta Versa HD linear accelerator. Methods Peripheral doses outside the electron applicator were measured using 6, 9, and 12 MeV beams at their respective maximum dose depths while maintaining a 100 cm source-to-surface distance. Measurements employed EBT3 films within solid water phantoms. The influence of field size on penumbra width and peripheral doses were examined using various cutouts (6 x 6 cm², 10 x 10 cm², and a 5 cm diameter circle) within a 10 × 10 cm² applicator, with gantry and collimator angles set to 0 degrees. Additionally, the impact of collimator angles on penumbra width and peripheral doses was explored, enhancing the understanding of dose distribution. Measured profiles were also compared with those calculated using Monaco treatment planning system. Results Findings showed that both penumbra width and peripheral dose values increased with energy across different field sizes and collimator angles. Root Mean Square Deviation (RMSD) analysis indicated deviations of 1.8 mm for penumbra and 1.1% for peripheral doses between measured profiles and Treatment Planning System (TPS) predictions for all field sizes. Notably, peripheral doses remained below 5% of the maximum dose at distances ranging from 10 to 15 mm away from the field edges, suggesting the potential for implementation of supplementary shielding strategies. Conclusion This study highlights the critical importance of considering peripheral doses in radiotherapy, emphasizing the need to evaluate the impact on healthy tissues outside the primary treatment area to ensure patient safety and mitigate long-term treatment-related side effects. The findings underscore the necessity of implementing appropriate measures to minimize peripheral doses.

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“…23 Hence, the distance which is near the face cannot reduce the pain but increase it because of the undesirable heating that results from close proximity to the lamp and the erythema in the surface of skin. 24,25 The other reason being, some patients cannot hold down the light. 26 We illustrated this study, if the intensity of the nearest distance was 45 cm (r) that corresponded to a surface A.…”

Section: Discussionmentioning

confidence: 99%

Determining the Effectivity of Infrared Distance to Eliminate Dental Pain Due to Pulpitis and Periodontitis

et al. 2020

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Objective The infrared rays is one of the treatments to relief of dental pain due to pulpitis or periodontitis. The ability of infrared to increase the pain threshold which make eliminating P substance on the inflammation area and inducing Aβ and Aδ fibers to activate γ-aminobutyrate (GABA) and neuropeptides to decrease the pain. Hence, reducing or eliminating dental pain. This study to get information about effectively distance between patients and infrared rays which can reduce or eliminate dental pain. Materials and Methods The explorative experimental research to determine the effectivity of the infrared rays’ distance: 45, 55, and 55 cm in reducing or eliminating dental pain. The material of infrared was tungsten with luminous light and the time for the lighting was 15 minutes. Statistical Analysis The data were obtained and analyzed using Wilcoxon’s signed rank test and Kruskal–Wallis test (α= 0.05). Results There were influenced of the infrared rays to reduce the dental pain as follow, distance 45 cm (p = 0.007), distance 55 cm (p = 0.026), and distance 65 cm (p = 0.007). The average scale reduction for distance 45 cm was 2.22 ± 0.83, the distance 55 cm was 3.44 ± 0.82, and the distance 65 cm was (1.78 ± 0.83). Therefore, according to Kruskal–Wallis test with p = 0.004 (p < 0.05) showed the significant difference between the scale to decrease of dental pain was the distance of 55. Conclusion Infrared rays located at a distance of 55 cm from patients might be more effective in relieving dental pain, compared with other distances tested.

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Accuracy evaluation of distance inverse square law in determining virtual electron source location in Siemens Primus linac

Abstract: According to the results, it is concluded that the ISL method can be considered as a good method for calculation of location in higher electron energies (14 MeV).

Cited by 8 publications

References 9 publications

Measurement‐based validation of a commercial Monte Carlo dose calculation algorithm for electron beams

Measurement‐based validation of a commercial Monte Carlo dose calculation algorithm for electron beams

Peripheral doses outside the electron applicators in an Elekta Versa HD Linac

Determining the Effectivity of Infrared Distance to Eliminate Dental Pain Due to Pulpitis and Periodontitis

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