The effects of cutouts on output, mean energy and percentage depth dose of 12 and 14 MeV electrons

Khaledy, N.; Arbabi, Amir; Sardari, Dariush

doi:10.4103/0971-6203.89970

Cited by 10 publications

(8 citation statements)

References 10 publications

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“…Such applicators are expected to affect output factors (OFs), percentage depth dose curves (PDDs), and the shape of beam profiles. In particular, the lack of lateral scatter equilibrium occurring in small beam sizes (2) results in a shift towards the phantom surface of the depth of maximum dose in the PDD curves (3) . Additionally, a contribution from scattered and bremsstrahlung radiation generated by the collimator systems is expected (4,5) .…”

Section: Introductionmentioning

confidence: 99%

Comparison between small radiation therapy electron beams collimated by Cerrobend and tubular applicators

Venanzio

Marinelli

Tonnetti

et al. 2015

J Applied Clin Med Phys

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The purpose of this study was to compare the dosimetric properties of small field electron beams shaped by circular Cerrobend blocks and stainless steel tubular applicators. Percentage depth dose curves, beam profiles, and output factors of small‐size circular fields from 2 to 5 cm diameter, obtained either by tubular applicators and Cerrobend blocks, were measured for 6, 10, and 15 MeV electron beam energies. All measurements were performed using a PTW microDiamond 60019 premarket prototype. An overall similar behavior between the two collimating systems can be observed in terms of PDD and beam profiles. However, Cerrobend collimators produce a higher bremsstrahlung background under irradiation with high‐energy electrons. In such irradiation condition, larger output factors are observed for tubular applicators. Similar dosimetric properties are observed using circular Cerrobend blocks and stainless steel tubular applicators at lower beam energies. However, Cerrobend collimators allow the delivery of specific beam shapes, conformed to the target area. On the other hand, in high‐energy irradiation conditions, tubular applicators produce a lower bremsstrahlung contribution, leading to lower doses outside the target volume. In addition, the higher output factors observed at high energies for tubular applicators lead to reduced treatment times.PACS number: 87.53.Bn, 87.55.Qr, 87.56.Fc

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Section: Introductionmentioning

confidence: 99%

Comparison between small radiation therapy electron beams collimated by Cerrobend and tubular applicators

Venanzio

Marinelli

Tonnetti

et al. 2015

J Applied Clin Med Phys

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“…These studies showed that the mixed beam has some advantages over electron or photon beams. For example, the electron beam is more sensitive to small fields [4] [5] than mixed or photon beams. Xiong et al conducted a research to optimize dose distribution of photon and electron combination in breast [6].…”

Section: Introductionmentioning

confidence: 99%

Comparing Nasal Cavity Radiotherapy Using Electron, Photon, Proton and Photon-Electron Beams

Khaledi¹,

Ahmadabad²,

Ebam³

et al. 2018

JCT

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Aim: Electron, photon or proton beams are used in radiotherapy for cancer treatment while each one may be used depending on depth and the location of tumor and normal tissues around the treatment target as well as economic issues. Materials and Methods: In this research, dose distribution by proton was measured by film dosimetry in nasal cavity Plexiglas phantom and Monte Carlo simulation. Then the DVH of treatment target and the posterior of treatment target of different beams were compared. The energies of electron, photon and proton were 9 MeV, 6 MV, and maximum 65 MeV, respectively. Due to a depth of 3.5 cm of CTV (Clinical Target Volume), Modulation Range was between 0-3.5 cm and SOBP (Spread-out Bragg Peak) was between 0-65 MeV. Results: Comparing the obtained DVH values, 95% dose coverage of target volume for electron, photon, proton and Photon-Electron beams were 88%, 98%, 98%, and 95%, respectively. However, doses above 40% that reached outside the target were 50%, 82%, 5%, and 44%, respectively. Conclusions: The results demonstrate the superiority of proton therapy in nasal cancer due to its better target volume coverage and the less amount of the dose reaching outside the target that is because of dose discharge in a small area and significant dose fall-off after Bragg peak.

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“…This capability leads to employ it in radiation therapy of nasal, breast, and parotid regions (1,2). On the other side, its usage is limited by the dependency of penumbra to the depth and influence of dose parameters of electron beam from the field size changing (3)(4)(5)(6)(7)(8). The issue of penumbra increment by depth is enhanced in some investigations by adding a narrow photon beam to the edge of the electron beam field (5) or mixing a low weight photon to electron beam field (4,9,10).…”

Section: Introductionmentioning

confidence: 99%

Investigation of Simultaneous Photons and Electrons Beam by Monte Carlo Code

Khaledi

Arbabi

Sardari

et al. 2015

Rep Radiother Oncol

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Background: Depending on the location and depth of tumor, the electron or photon beams might be used for treatment. Electron beam have some advantages over photon beam for treatment of shallow tumors to spare the normal tissues beyond of the tumor. In the other hand, the photon beam are used for deep targets treatment. Both of these beams have some limitations, for example, the dependency of penumbra with depth, and the lack of lateral equilibrium for small electron beam fields. Objectives: In this study, improvement of the penumbra and Dmax changes will be investigated. Also the effects of cut-outs on the beam parameters prepared as well. Patients and Methods:In first, we simulated the conventional head configuration of Varian 2300 for 16 MeV electron, and the results approved by benchmarking the percent depth dose (PDD) and profile of the simulation and measurement. In the next step, a perforated Lead (Pb) sheet with 1 mm thickness placed at the top of the applicator holder tray. This layer producing bremsstrahlung x-ray and a part of the electrons passing through the holes, in result, we have a simultaneous mixed electron and photon beam. For making the irradiation field uniform, a layer of steel placed after the Pb layer. The simulation was performed for 10 × 10, and 4 × 4 cm 2 field size. Results: The measured R50 and RP for 10 × 10 cm2 field were 6.5 and 7.8 cm, respectively. The photon percentage for 1 mm thickness with 0.2, 0.3, and 0.5 cm holes diameter Lead layer target was about 33%, 32%, and 28% and for 2 mm targets punched with 0.2, 0.3, and 0.5 cm holes, the x-ray percentages were 43%, 41%, and 35%. Conclusions: This study showed the advantages of mixing the electron and photon beam by reduction of pure electron's penumbra dependency with the depth, especially for small fields, also decreasing of dramatic changes of PDD curve with irradiation field size.

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The effects of cutouts on output, mean energy and percentage depth dose of 12 and 14 MeV electrons

Cited by 10 publications

References 10 publications

Comparison between small radiation therapy electron beams collimated by Cerrobend and tubular applicators

Comparison between small radiation therapy electron beams collimated by Cerrobend and tubular applicators

Comparing Nasal Cavity Radiotherapy Using Electron, Photon, Proton and Photon-Electron Beams

Investigation of Simultaneous Photons and Electrons Beam by Monte Carlo Code

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