{"entity":{"id":"organs-at-risk","kind":"term","name":"Organs at risk and dose constraints","aka":[],"tldr":"The healthy organs near a tumour that limit how much dose can be given, each with a maximum dose or dose-volume limit the plan must respect (for example, keeping the spinal cord below about 45 to 50 Gy).","summary":"Every plan trades tumour dose against the tolerance of nearby organs: spinal cord, brainstem, optic nerves, lungs, heart, kidneys, rectum and bladder among them. Dose constraints come from decades of outcome data, summarised in the QUANTEC reviews and, for stereotactic treatment, HyTEC, and are expressed as maximum point doses or the volume allowed above a threshold. Meeting the constraints is what the optimiser and the planner negotiate.","asOf":"2026-09-17","wikipedia":"https://en.wikipedia.org/wiki/Radiation_treatment_planning","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Radiation_treatment_planning"}],"tags":["radiation-wave1"],"related":[],"cancers":[],"sections":[],"technologies":["imrt-igrt","vmat","treatment-planning-systems"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Treatment jargon"},"route":"/terms/organs-at-risk/","neighbours":{"technology":[{"id":"adaptive-radiotherapy","kind":"technology","name":"Adaptive radiotherapy (online replanning)","route":"/technologies/adaptive-radiotherapy/"},{"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":"treatment-planning-systems","kind":"technology","name":"Radiotherapy treatment planning and QA software","route":"/technologies/treatment-planning-systems/"},{"id":"tumour-control-probability-models","kind":"technology","name":"Tumour control and normal tissue complication probability (TCP and NTCP)","route":"/technologies/tumour-control-probability-models/"},{"id":"vmat","kind":"technology","name":"Volumetric modulated arc therapy (VMAT)","route":"/technologies/vmat/"}],"term":[{"id":"target-delineation-variability","kind":"term","name":"Variation between clinicians in drawing the radiotherapy target","route":"/terms/target-delineation-variability/"}],"paper":[{"id":"paper-flame-focal-boost-prostate-jco-2021","kind":"paper","name":"Focal boost to the intraprostatic tumor in external beam radiotherapy for patients with localized prostate cancer: results from the FLAME randomized phase III trial","route":"/key-papers/paper-flame-focal-boost-prostate-jco-2021/"},{"id":"paper-vinod-delineation-uncertainty-review-radiother-oncol-2016","kind":"paper","name":"Uncertainties in volume delineation in radiation oncology: a systematic review and recommendations for future studies","route":"/key-papers/paper-vinod-delineation-uncertainty-review-radiother-oncol-2016/"}],"trial":[{"id":"nrg-cc001","kind":"trial","name":"NRG CC001","route":"/trials/nrg-cc001/"},{"id":"rtog-0617","kind":"trial","name":"RTOG 0617","route":"/trials/rtog-0617/"}]}}