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 techniq ues and compared to those for conventional shielding blocks. The MLC p roved faster in all cases of treatment delivery providing time reducti ons of 19-48% for parallel opposed beams and 6-44% for conformal isoce ntric beams. The workload in the mould room and workshop would be redu ced if multileaf collimation is used. Time spent manufacturing and mou nting blocks (average 2 h 30 min and 37 min, respectively) is eliminat ed for the techniques studied. The physics process for generating conf ormal MLC beams proved faster (average 1 h 36 min) than for blocks (av erage 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.