Electron beam collimation with the photon MLC for standard electron treatments.

Mueller, Silvan; Fix, Michael; Henzen, Dominik; Frei, Daniel; Frauchiger, Daniel; Lössl, Kristina; Stampanoni, Marco F M; Manser, Peter (2018). Electron beam collimation with the photon MLC for standard electron treatments. Physics in medicine and biology, 63(2), 025017. Institute of Physics Publishing IOP 10.1088/1361-6560/aa9fb6

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Standard electron treatments are nowadays still performed using standard or molded patient-specific cut-outs placed in the electron applicator. Replacing cut-outs and electron applicators with the photon multileaf collimator (pMLC) for electron beam collimation would make standard electron treatments more efficient and would facilitate advanced treatment techniques like modulated electron radiotherapy (MERT) and mixed beam radiotherapy (MBRT). In this work, a multiple source Monte Carlo beam model for pMLC shaped electron beams commissioned at a source to surface distance (SSD) of 70 cm is extended for SSDs up to 100 cm and validated for several Varian treatment units with field sizes typically used for standard electron treatments. Measurements and dose calculations agree generally within 3% of the maximal dose or 2 mm distance to agreement. To evaluate the dosimetric consequences of using pMLC collimated electron beams for standard electron treatments, pMLC based and cut-out based treatment plans are created for a left and a right breast boost, a sternum, a testis and a parotid gland case. The treatment plans consist of a single electron field either alone (1E) or in combination with two 3D conformal tangential photon fields (1E2X). For each case, a pMLC plan with similar treatment plan quality in terms of dose homogeneity to the target and absolute mean dose values to the organs at risk (OARs) compared to a cut-out plan is found. The absolute mean dose to an OAR is slightly increased for pMLC based compared to cut-out based 1E plans if the OAR is located laterally close to the target with respect to beam direction or if a 6 MeV electron beam is used at an extended SSD. In conclusion, treatment plans using cut-out collimation can be replaced by plans of similar treatment plan quality using pMLC collimation with accurately calculated dose distributions.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Clinic of Radiation Oncology > Medical Radiation Physics
04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Clinic of Radiation Oncology

UniBE Contributor:

Mueller, Silvan; Fix, Michael; Henzen, Dominik; Frei, Daniel; Frauchiger, Daniel; Lössl, Kristina and Manser, Peter

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0031-9155

Publisher:

Institute of Physics Publishing IOP

Language:

English

Submitter:

Beatrice Scheidegger

Date Deposited:

09 Apr 2018 12:24

Last Modified:

10 Apr 2018 06:32

Publisher DOI:

10.1088/1361-6560/aa9fb6

PubMed ID:

29214984

Uncontrolled Keywords:

Monte Carlo electron beam collimation electron therapy multileaf collimator

BORIS DOI:

10.7892/boris.107869

URI:

https://boris.unibe.ch/id/eprint/107869

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