{"entity":{"id":"imrt-term","kind":"term","name":"IMRT / IGRT / VMAT (modern external beam radiotherapy)","aka":["IMRT","IGRT","VMAT","intensity-modulated radiotherapy","intensity-modulated","image-guided radiotherapy","external beam","external-beam","external beam radiotherapy","EBRT","conformal","3D-conformal"],"tldr":"Radiation beams shaped and varied in intensity from multiple angles, or while the machine rotates around the patient (VMAT), so the dose hugs the tumour and misses healthy tissue, checked against imaging before each session so it lands where planned. It cut dry mouth in head and neck cancer and rectal toxicity in prostate cancer.","summary":"Intensity-modulated radiotherapy (IMRT) sculpts dose with a multileaf collimator; volumetric modulated arc therapy (VMAT) does it while the machine rotates, in minutes; image-guided radiotherapy (IGRT) uses cone-beam CT or surface tracking before each fraction. Together they cut xerostomia in head and neck cancer (PARSPORT), rectal toxicity in prostate cancer and allowed hypofractionation. Planning quality depends on contouring, now aided by AI auto-segmentation. Proton therapy adds a sharper depth stop for selected tumours.","asOf":"2026-09-09","wikipedia":"https://en.wikipedia.org/wiki/Radiation_therapy#Intensity-modulated_radiation_therapy_(IMRT)","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Radiation_therapy#Intensity-modulated_radiation_therapy_(IMRT)"}],"tags":[],"related":["hypofractionation","gray-unit","sbrt-term"],"cancers":[],"sections":["radiation"],"technologies":["imrt-igrt","proton-therapy","auto-contouring-ai"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Procedures"},"route":"/terms/imrt-term/","neighbours":{"term":[{"id":"brachytherapy-term","kind":"term","name":"Brachytherapy (internal radiotherapy)","route":"/terms/brachytherapy-term/"},{"id":"chemoradiation","kind":"term","name":"Chemoradiation (chemoradiotherapy, CRT)","route":"/terms/chemoradiation/"},{"id":"gray-unit","kind":"term","name":"Gray unit (Gy)","route":"/terms/gray-unit/"},{"id":"hypofractionation","kind":"term","name":"Hypofractionation (fewer, larger radiotherapy doses)","route":"/terms/hypofractionation/"},{"id":"sbrt-term","kind":"term","name":"Stereotactic body radiotherapy (SBRT / SABR)","route":"/terms/sbrt-term/"}],"section":[{"id":"radiation","kind":"section","name":"Radiation Therapy","route":"/fronts/radiation/"}],"technology":[{"id":"auto-contouring-ai","kind":"technology","name":"AI auto-contouring and adaptive planning","route":"/technologies/auto-contouring-ai/"},{"id":"c-arm-linac","kind":"technology","name":"C-arm medical linear accelerators (TrueBeam, Versa HD and others)","route":"/technologies/c-arm-linac/"},{"id":"imrt-igrt","kind":"technology","name":"IMRT / IGRT (modern external beam)","route":"/technologies/imrt-igrt/"},{"id":"proton-therapy","kind":"technology","name":"Proton therapy","route":"/technologies/proton-therapy/"},{"id":"vmat","kind":"technology","name":"Volumetric modulated arc therapy (VMAT)","route":"/technologies/vmat/"}]}}