MLC performance prognosis using a degradation model based on trajectory log data from a daily test.

Purpose: This paper investigates the feasibility of implementing a predictive maintenance program for a multileaf collimator (MLC) based on data collected in trajectory logs (TLs) obtained by conducting a simple daily test, with the aim of minimizing unscheduled downtime.

Methods: A dynamic field test was designed, and the TLs generated in the course of daily administration in a linear accelerator were collected to evaluate trajectory deviations of the MLC leaves as well as interlocks (COL 420219/20, COL 420207/08) reported by the machine. During this evaluation, we observed that the trajectory deviations of some leaves increased up to a threshold value beyond which certain interlocks began to appear in treatment fields in those leaves.

A method to improve fluence resolution derived from two-dimensional detector array measurements for patient-specific IMRT verification using the information collected in dynalog files.

This paper proposes a method for improving the resolution of the fluence derived from detector array measurement using the information collected in dynalog files. From dynalog information, a file is generated with the actual multileaf collimator (MLC) positions and used as input to the treatment planning system (TPS) to obtain the dynalog-derived fluence and the theoretical response over the detector array. In contrast with the measured response, this theoretical response allows for correction of the dynalog-derived fluence and translation into the reconstructed fluence.