Quality assurance of intensity-modulated radiotherapy

Intensity-modulated radiation therapy (IMRT) requires the use of inverse treatment planning and nonuniform fluence beams delivered by a series of complex radiation portals. The quality assurance procedures for conventional three-dimensional conformal radiation therapy (3D-CRT) have been developed and are in worldwide clinical use, but the more complex nature of IMRT limits the application of much of the quality assurance (QA) procedures developed for IMRT. Although consensus has not yet been reached regarding which procedures will eventually become recommended by official organizations, the field is rapidly coming to agreement on a basic set of procedures. This manuscript describes some of the novel techniques recently developed for IMRT QA, both for the validation of the calculated dose distribution and for assuring that the dose distribution reaches its intended targets.