Etymology.

If anyone says they’re not at least a little confused by the term intensity modulated radiotherapy (IMRT), they’re lying. This update on the initial 2011 ASTRO commission on IMRT safety is here to define the many techniques that can fall under this umbrella and delve into recommended routine quality assurance protocols. Broadly speaking, IMRT can refer to any multileaf collimation be it static (“step and shoot” with no collimator or gantry movement during radiation delivery), dynamic (“sliding window” with collimator but no gantry movement), or rotational such as volumetric modulated arc therapy (VMAT with both collimator and gantry movement). And these can be either forward or inverse planned. QA recommendations get more rigorous with increasing technique complexity, but Table 3 provides a good summary. | Morna, Pract Radiat Oncol 2022