Dosimetric characteristics of an electron multileaf collimator for modulated electron radiation therapy

Abstract

Modulated electron radiation therapy (MERT) has been proven as an effective way to deliver conformal dose distributions to shallow tumors while sparing distal critical structures and surrounding normal tissues. It had been shown that a dedicated electron multileaf collimator (eMLC) is necessary to reach the full potential of MERT. In this study, a manually‐driven eMLC for MERT was investigated. Percentage depth dose (PDD) curves and profiles at different depths in a water tank were measured using ionization chamber and were also simulated using the Monte Carlo method. Comparisons have been performed between PDD curves and profiles collimated using the eMLC and conventional electron applicators with similar size of opening. Monte Carlo simulations were performed for all electron energies available (6, 9, 12, 15, 18 and 20 MeV) on a Varian 21EX accelerator. Monte Carlo simulation results were compared with measurements which showed good agreement (<%1mm). The simulated dose distributions resulting from multiple static electron fields collimated by the eMLC agreed well with measurements. Further studies were carried out to investigate the properties of abutting electron beams using the eMLC, as it is an essential issue that needs to be addressed for optimizing the MERT outcome. A series of empirical formulas for abutting beams of different energies have been developed for obtaining the optimum gap sizes, which can highly improve the target dose uniformity.PACS numbers: 87.53.Wz, 87.53.Hv

Design and production of 3D printed bolus for electron radiation therapy

“…(2) IMET is similar, in concept, to inverse treatment planning (or optimization) of IMRT and uses multiple, optimally-weighted beamlets to deliver dose conformal to the PTV. (3) Beamlets are shaped by a conventional photon multileaf collimator (pMLC), (4)(5)(6)(7)(8) specific add-on electron multileaf collimator (eMLC), (9)(10)(11)(12)(13) or few-leaf electron collimator (FLEC). (14,15) Though the MERT techniques show promising results in terms of PTV coverage and normal tissue sparing, they are complex in clinical implementation and dose delivery, thus compromising the efficiency of treatment.…”

A source model for modulated electron radiation therapy using dynamic jaw movements

“…[1][2][3][4][5][6][7][8] The E-MLC would be attached either on an existing electron applicator or on a retractable applicator. A second approach 9-12 is to use the photon MLC for the collimation of electron beams.…”

Delivery validation of an automated modulated electron radiotherapy plan

“…Various groups [1][2][3][4][5] have reported on the feasibility of using the photon MLC as a possible collimation device, while others [6][7][8][9][10][11][12] have manufactured add-on electron MLCs that are positioned closer to the patient in an effort to minimize the penumbra width due to air scatter. It was reported that acceptable penumbra can be obtained with photon MLCs by using SSDs in the 70 cm range.…”