Design and fabrication of the control part of a prototype multileaf collimator system

Abstract

Multileaf collimator (MLC) is among the radiation field shaping systems used for conformal radiotherapy and intensity modulation radiation therapy techniques. The MLC system we have designed and fabricated includes 52 leaves, 52 stepper motors, 2 DC motors, 16 programmable logic controllers (PLC) and one Human Machine Interface (HMI). This system is able to be mounted on the conventional linear accelerators (linac) as an add-on accessory. The 52 leaves are mounted on 2 carriages that are moved independently. The leaves sequence acquired from an image processing of CT images is used to arrange leaves. This sequence is saved in a text file. The leaves are arranged as follows: a) using HMI, it is possible to test the operation of PLCs and enter the numerical values of the leaves edges by hand; b) using labVIEW program, an executable file is developed that is graphical user interface between the operator and the control system of MLC. In this program, it is possible to load the file including sequence leaves edges and then view the leaves arrangement obtained through the encoder feedback of each motor.