Monte Carlo portal dosimetry

Chin, Mary

doi:10.1118/1.2040709

Cited by 2 publications

(3 citation statements)

References 109 publications

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“…The source model producing the best agreement with measured data was chosen to be the fine-tuned model. (11) The number of histories in the DOSXYZnrc input were specified to produce a statistical uncertainty in calculated dose approaching 1%. This choice involved simulation of the order of 2 × 10 7 to 2 × 10 8 primary particle histories, depending on energy, field size, and SSD.…”

Section: B2 Dose Calculationsmentioning

confidence: 99%

Electron beam therapy at extended source‐to‐surface distance: a Monte Carlo investigation

O’Shea

Foley

Rajasekar

et al. 2008

J Applied Clin Med Phys

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Electron‐beam therapy is used to treat superficial tumors at a standard 100 cm source‐to‐surface distance (SSD). However, certain clinical situations require the use of an extended SSD. In the present study, Monte Carlo methods were used to investigate clinical electron beams, at standard and non‐standard SSDs, from a Siemens Oncor Avant Garde (Siemens Healthcare, Erlangen, Germany) linear accelerator (LINAC). The LINAC treatment head was modeled in BEAMnrc for electron fields 5 cm in diameter and 10×10 cm, 15×15 cm, and 20×20 cm; for 6 MeV, 9 MeV, and 12 MeV; and for 100 cm, 110 cm, and 120 cm SSD. The DOSXYZnrc code was used to calculate extended SSD factors and dose contributions from various parts of the treatment head.The main effects of extended SSD on water phantom dose distributions were verified by Monte Carlo methods. Monte Carlo–calculated and measured extended SSD factors showed an average difference of ±1.8%. For the field 5 cm in diameter, the relative output at extended SSD declined more rapidly than it did for the larger fields. An investigation of output contributions showed this decline was mainly a result of a rapid loss of scatter dose reaching the dmax point from the lower scrapers of the electron applicator. The field 5 cm in diameter showed a reduction in dose contributions; the larger fields generally showed an increased contribution from the scrapers with increase in SSD. Angular distributions of applicator‐scattered electrons have shown a large number of acute‐angle electron tracks contributing to the output for larger field sizes, explaining the shallow output reduction.PACS numbers: 87.53.Wz, 87.53.Vb, 87.53.Hv

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Section: B2 Dose Calculationsmentioning

confidence: 99%

Electron beam therapy at extended source‐to‐surface distance: a Monte Carlo investigation

O’Shea

Foley

Rajasekar

et al. 2008

J Applied Clin Med Phys

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“…Moreover, changes in the patient's positioning and anatomy changes cannot be detected. All of these can be checked in the 206 K. BadraouiČuprová: Radioprotection 49(3), 205-211 (2014) dose verifications during treatment (Chin, 2008) and this paper will be dedicated entirely to such verifications.…”

Section: Introductionmentioning

confidence: 99%

“…In the first approach, the transmission portal dose image is predicted and compared with the acquired one (Chin, 2008). This method is called direct transmission dosimetry and will be considered in this paper.…”

Section: Introductionmentioning

confidence: 99%

Transmission portal in vivo dosimetry by means of the Monte Carlo method and the mathematical programming language MATLAB

Cuprova

2014

Radioprotection

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-Modern radiotherapy has increased demand for dose delivery verification. In this paper transmission portal dosimetry was considered. Portal detectors are a promising tool for 2D dosimetric verification and they are nowadays one of the most widely investigated topics. In this study an Electronic Portal Imaging Device (EPID) was positioned below the patient and the transmission images were captured during the irradiation. The principle of this verification consists of comparison of the acquired images with images predicted on the basis of the entrance fluence map and the tissue distribution in the patient. Such verification is not performed at any radiotherapy department in the Czech Republic. There is no system available for the prediction of transmission portal images. Even worldwide, there is still a lack of commercially available solutions. The aim of this paper is to present a new method of prediction of transmission portal images by means of the Monte Carlo (MC) method and the mathematical programming language MATLAB. The MC code EGSnrc (Electron Gamma Shower) was used. The validity of the presented method was verified by comparison of the predicted images with the acquired ones. The acquisition of EPID images was performed at the Hospital Na Bulovce. Three different validation tests were performed. In the first case, the EPID was irradiated by regular and irregular fields while there was nothing present in the beam path. In the second case, a water-equivalent phantom was added to the EPID and was irradiated by a number of irregular fields. In the third case, a real patient was present in the beam path and the EPID images were acquired during the patient's treatment. The patient was irradiated by 8 treatment fields and the portal images were acquired during 5 treatment fractions. All of the acquired images were compared with the MC predicted ones by gamma analysis with gamma criteria of 3%, 3 mm. The average gamma values were 0.31−0.4, 0.34−0.4 and 0.35−0.61 in the first, second and third case, respectively. The results validate the developed method and demonstrate that MC is an effective tool for portal dose image prediction. MC may be favourably used for in vivo transmission dosimetry.

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Monte Carlo portal dosimetry

Cited by 2 publications

References 109 publications

Electron beam therapy at extended source‐to‐surface distance: a Monte Carlo investigation

Electron beam therapy at extended source‐to‐surface distance: a Monte Carlo investigation

Transmission portal in vivo dosimetry by means of the Monte Carlo method and the mathematical programming language MATLAB

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