ABSTRACT
Objective:To analyze the 6-year operation faults of PHILIPS Brilliance big bore CT, identify the common problems, make corresponding maintenance plans, reduce the incidence of failures, and carry out simulation prediction of the occurrence rate of failures in the next few years.Methods:The failure data of Brilliance big bore CT from June 2012 to June 2018 were collected, and the curve estimation function in SPASS 19.0 software and the pareto diagram were used to analyze the relationship between the number of failures, time and failure types, and the prediction was made.Results:A total of 28 faults occurred during the 6-year opeation of Brilliance big bore CT. During the first half year, five times of faults occurred with the highest fault rate and then tended to stabilize. The linear function model was obtained using the curve estimation: y=-0.033 x+ 2.099( y for the number of fault, unit for times, x for the unit of time for half a year), the model of R2=0.003. In the next three years, approximately twice faults occurred within half year. The pareto chart showed that 16 faults occurred during data collection, including 3 faults in the treatment bed and 3 faults in the power supply system, respectively. The accumulative ratio of the above three faults was 71.4%, which were the main fault sources. Conclusion:The fault statistical analysis of Brilliance big bore CT is helpful for department maintenance personnel to better understand CT, develop effective maintenance programs, reduce the occurrence of faults, and predict the incidence of faults in the future.
ABSTRACT
Objective To evaluate the penumbra of a new multileaf collimator equipped with Elekta Synergy accelerator. Methods The penumbra were derived from beam profiles measured in air and water using PinPoint ion chamber with PTW MP3 water phantom. Variations of penumbra with X-ray beam energy, depth in water, and leaf position were investigated. Results The penumbra in air for 6 MV X-ray was 2 mm less than that at depth of maximal dose in water. The penumbra of leaf side was 1 mm less than that of the leaf end. The penumbra had close relationship with beam energy, depth in water and leaf position. Penumbra was increased with beam quality and water depth. The leaf position had great influence on the penumbra. Conclusions The penumbra of the multileaf collimator is related to its original design and radiation delivery technique. Special considerations should be taken into during treatment planning.Regular measurement should be performed to guarantee the delivery quality.