Levels of leakage radiation from electron collimators of a linear accelerator

Das, K. R.; Cramb, Jim; Miller, Ryan M.; Kenny, M.B.; Patterson, William R.; Ackerly, Trevor; Perkins, Amy E.; Chongkitivitya, K.

doi:10.1016/0958-3947(91)90055-7

Cited by 3 publications

(4 citation statements)

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“…7.42 (PTW Freiburg). Next, the off-axis ratios (OARs) on the cross-line (transverse direction) dose profiles were measured at a depth of 5 mm (R s ), the depth of dose maximum (R 100 ), the depth of a 90% dose (R 90 ), the depth of a 50% dose (R 50 ), and the practical range (R p ) as defined by AAPM TG25 [18] using a TM31010 (PTW Freiburg) thimble ionization chamber with an effective volume of 0.125 cm 3 . The doses measured at off-axis points of interest were normalized to the dose at the central beam axis in a water phantom for the given electron energy.…”

Section: Energy (Mev)mentioning

confidence: 99%

Monte Carlo simulation and measurement of radiation leakage from applicators used in external electron radiotherapy

et al. 2013

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External electron radiotherapy is performed using a cone or applicator to collimate the beam. However, because of a trade-off between collimation and scattering/bremsstrahlung X-ray production, applicators generate a small amount of secondary radiation (leakage). We investigate the peripheral dose outside the radiation field of a Varian-type applicator. The dose and fluence outside the radiation field were analyzed in a detailed Monte Carlo simulation. The differences between the calculation results and data measured in a water phantom in an ionization chamber were less than ±1% in regions more than 3 mm below the surface of the phantom and at the depth of dose maximum. The calculated fluence was analyzed inside and outside the radiation field on a plane just above the water phantom surface. Changing the electron energy affected the off-axis fluence distribution outside the radiation field; however, the size of the applicator had little effect on this distribution. For each energy, the distributions outside the radiation field were similar to the dose distribution at shallow depths in the water phantom. The effect of secondary electrons generation by photon transmission through the alloy making up the lowest scraper was largest in the region from the field edge to directly below the cutout and at higher beam energies. The results of the Monte Carlo simulation confirm that the peripheral dose outside the field is significantly affected by radiation scattered or transmitted from the applicator, and the effect increases with the electron energy.

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Section: Energy (Mev)mentioning

confidence: 99%

Monte Carlo simulation and measurement of radiation leakage from applicators used in external electron radiotherapy

et al. 2013

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“…For high‐energy electron beams, the out‐of‐field electron component is usually produced primarily via (2) and (3). For lower‐energy electron beams, scatter radiation occurs 12,13 . For 4‐MeV electron beams, the out‐of‐field dose peak may be caused by scattering electrons originating from the rounded surface of the MLC 14 .…”

Section: Discussionmentioning

confidence: 99%

“…For lower-energy electron beams, scatter radiation occurs. 12,13 For 4-MeV electron beams, the out-of-field dose peak may be caused by scattering electrons originating from the rounded surface of the MLC. 14 According to our results, the peripheral dose peak gradually weakened with an increasing number of LA layers, which was likely caused by the low penetration depth of the electron beams.…”

Section: D | Shielding Effect At 20-cm Depthmentioning

confidence: 99%

Shielding effect of a lead apron on the peripheral radiation dose outside the applicator of electron beams from an Elekta linear accelerator

Zhang

Wang

et al. 2020

J Applied Clin Med Phys

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To evaluate the shielding effect of lead aprons (LAs) on peripheral radiation doses outside the applicator of electron beams from a linear accelerator.Methods: Out-of-field radiation doses of 4-, 6-, 8-, 10-, 12-, and 15-MeV electron beams from an Elekta Synergy linear accelerator (linac) were measured by thermoluminescence dosimeters (TLD) at different depths (0, 0.5, 1.0, and 2.0 cm) and distances from the applicator edge (0-58 cm) in a water-equivalent slab phantom with a different number of layers of LA shielding (0-5 layers). Measurements were performed by 6 × 6, 10 × 10, 14 × 14, and 20 × 20-cm 2 applicators at a gantry and collimator angle of 0°. The out-of-field radiation dose profiles were normalized to the maximum dose of every energy and measuring depth. Results:The out-of-field radiation doses (beyond 3 cm away from the field edge) decreased with an increase in the number of LA layers and distance away from the central beam axis (CAX). After shielding with the LA, the out-of-field doses decreased by up to approximately 99% compared with the no shielding group. For 4-MeV electron beams, there was a peak at 24.5 cm from the CAX, which weakened with an increasing number of LA layers. Conclusion:The shielding effect of the LA varied for a different number of LA layers as well as different depths and distances away from the CAX. Four LA layers were sufficient for shielding out-of-field doses of 4-15-MeV electron beams. K E Y W O R D S electron beams, out-of-field radiation, shielding effect of LA 1 | INTRODUCTION Advances in radiotherapy have greatly improved the ability to deliver highly conformal doses to tumors while minimizing doses to surrounding normal tissues. Despite this tremendous progress, there remains a general concern about out-of-field radiation. Since the beginning of the 1950s, megavoltage electron beams have been used as an important treatment modality in modern radiotherapy owing to the advantage of a sharp dose drop to off beyond the tumor site. Electron therapy has often been used in the treatment of

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“…In addition to this, it is known that the part of the scattered and transmitted radiation that cannot be neglected leaks from the applicators and causes undesirable doses outside the treatment area. [5][6][7][8][9][10][11] The accuracy and efficacy of treatment in breast RT should involve accurate measurement of target and local surrounding tissue doses. Due to the excellent dosimetric properties, for example, the wide range of linearity of dose characteristic, the good lowest detection limit, near tissue equivalence and the low energy dependence the BeO detectors are predestined for dosimetric use.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive evaluation of electron radiation dose using beryllium oxide dosimeters at breast radiotherapy

et al. 2019

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Introduction:In this study, the differences between calculated and measured dose values were then analysed to assess the performance, in terms of accuracy, of the tested treatment planning system (TPS) algorithms applied to calculate electron beam dose targeted and non-targeted the breast region.Materials and methods:The beryllium oxide (BeO) dosimeters placed on the female RANDO phantom were irradiated 12 MeV electron energy with medical linear accelerator and repeatedly read in the Risø thermoluminescence (TL)/optically stimulated luminescence (OSL) system via OSL method at least three times.Results:For electron treatment, one made quantitative comparisons of the dose distributions calculated by TPSs with those from the measurements by OSL at various points in the RANDO phantom.The mean dose measured from the dosimeters placed on the female RANDO phantom target left breast region was 160 cGy and non-target right breast region was 1·2 cGy. Analysis of Generalised Gaussian Pencil Beam (GGPB) and Electron Monte Carlo (eMC) algorithms for determined region mean point dose values, respectively, 174 and 164 cGy. Two algorithms for non-targeted region calculated same point dose values of 0·2 cGy.Conclusions:The results of this study showed that BeO dosimeters can be used with OSL method in radiotherapy applications and it is a very important tool for the determination of targeted/non-targeted absorbed dose.

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Levels of leakage radiation from electron collimators of a linear accelerator

Cited by 3 publications

References 0 publications

Monte Carlo simulation and measurement of radiation leakage from applicators used in external electron radiotherapy

Monte Carlo simulation and measurement of radiation leakage from applicators used in external electron radiotherapy

Shielding effect of a lead apron on the peripheral radiation dose outside the applicator of electron beams from an Elekta linear accelerator

Comprehensive evaluation of electron radiation dose using beryllium oxide dosimeters at breast radiotherapy

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