Statistical Analysis of Corrective Maintenance in Linear Accelerators Used in Radiotherapy

Knowing the downtime of linear accelerators (LINACs), as well as the intermediate time between failures, is essential to plan and carry out timely and reliable radiotherapy treatments. The purpose of this study is to analyze the data in the service reports of LINACs installed in four radiotherapy centers, by calculating indicators and metrics of their maintenance, as well as studying factors linked to their downtime, such as the spare parts used in the repairs of the equipment.

The maintenance database of LINAC of the commercial house Varian Medical Systems, was analyzed, and distributed in 5 years of a Clinac iX and a Clinac 2100CD, 4 years of a Clinac 21EX and a Clinac 2100CD, and 3 years of a Clinac 600C, located in different medical centers of oncological radiotherapy in the country. The data were classified according to the equipment, interlock, and area of failure in the equipment.

On average, 20 corrective maintenance tasks were performed annually for each equipment, and 33.9% of the corrective maintenance tasks performed were caused by the multileaf collimator (MLC) interlock. Of the three possible types of interlocks (major, minor, and dosimetry), 83% of the time, a minor type of interlock occurs. Regarding the location of the faults, 32% occur in the MLC. In addition, it was determined that the most requested spare part is the "Half Leaf MLC Motor."

Collecting data associated with the downtime of LINACs and using them to calculate the indicators and metrics proposed in this research will allow for monitoring and implementing improvements in the planning of maintenance and treatments. Likewise, studying the demand for spare parts necessary to perform maintenance ensures proper inventory management.