Multileaf collimation versus conventional shielding blocks: a time and motion study of beam shaping in radiotherapy

The work processes for the planning and delivery of shaped beams using a Philips multileaf collimator were studied for two treatment techniques and compared to those for conventional shielding blocks. The MLC proved faster in all cases of treatment delivery providing time reductions of 19-48% for parallel opposed beams and 6-44% for conformal isocentric beams. The workload in the mould room and workshop would be reduced if multileaf collimation is used. Time spent manufacturing and mounting blocks (average 2 h 30 min and 37 min, respectively) is eliminated for the techniques studied. The physics process for generating conformal MLC beams proved faster (average 1 h 36 min) than for blocks (average 2 h 30 min); this was not so for parallel opposed beams. Overall the results suggest that using the MLC is a time- and resource-saving alternative to blocks