A proposal for quality assurance of multi-leaf collimators

Multi-leaf collimators (MLC's) are rapidly entering clinical service in many Institutes through-out the World. Commercial MLC's are reliable but highly complex devices that have new and sometimes complex maintenance and quality assurance (QA) requirements. The experience gained from installing the prototype Philips MLC and from using and maintaining two production model Philips MLC's - one four years old, one six months old - will be used to define the requirements of a QA schedule for MLC's. Problems specific to MLC's such as leaf positioning and radiation leakage between the leaves will be discussed and methods for measuring these problems presented. Recommendations for the frequency for performing these checks based on our experiences will be made. Preventative maintenance times, machine down times due to the MLC and planned Quality Control down times will be reported