Design of a computer-controlled multileaf collimator for advanced electron radiotherapy

Abstract

A multileaf collimator for electrons (eMLC) has been designed that fulfils the technical requirements for providing advanced irradiation techniques with electrons. In the present work, the basic design parameters of leaf material, leaf height, leaf width and number of leaves as well as leaf overtravel and leaf shape were determined such that an eMLC with motorized leaves can be manufactured by a company specialized in MLC technology. For this purpose, a manually driven eMLC with variable source-to-collimator distance (SCD) was used to evaluate the chosen leaf specification and investigate the impact of the SCD on the off-axis dose distribution. In order to select the final SCD of the eMLC, a compromise had to be found between maximum field size, minimum beam penumbra and necessary distance between eMLC and isocentre to eliminate patient realignments during gantry rotation. As a result, the eMLC is placed according to the target position at 72 and 84 cm SCD, respectively. This feature will be achieved by interchangeable distance holders. At these SCDs, the corresponding maximum field sizes at 100 cm source-to-isocentre distance are 20 x 20 cm and 17 x 17 cm, respectively. Finally, the off-axis dose distribution at the maximum opening of the eMLC was improved by fine-tuning the settings of the accelerator jaws and introducing trimmer bars above the eMLC. Following this optimization, a prototype eMLC consisting of 2 x 24 computer-controlled brass leaves is manufactured by 3D Line Medical Systems.

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

“…Improved plan quality can be achieved using modulated electron radiation therapy (MERT) 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 . MERT can be accomplished by sophisticated techniques based on modulation of multiple electron energies and electron beam weights or intensities, which is further classified into two categories: segmented‐field electron conformal therapy (ECT) and intensity‐modulated electron therapy (IMET).…”

Applications to Radiotherapy Using Three Different Dosimetric Tools: MAGIC-f Gel, PENELOPE Simulation Code and Treatment Planning System

“…Recent authors have studied different possibilities for realization of this new radiotherapy technique, An example being the construction of the multi-leaf collimators for a specific electron beam [32]. The possibility of using the multi-leaf collimators using only photon beams [33] or development of collimators additional to maintain a standard feature of the treatment with electrons beams [34,35].…”

Production of patient‐specific electron beam aperture cut‐outs using a low‐cost, multi‐purpose 3D printer

“…Modulation of the electron fields may improve the dose conformity 3 and has been extensively investigated using the photon multi‐leaf collimator (MLC) 4, 5, 6 or a dedicated electron MLC 7, 8. Nevertheless, the use of static electron fields remains common 9 and collimation is typically performed using aperture cut‐outs placed in the electron applicator at a small distance from the patient's skin 10…”