Radiotherapieplanning

Radiotherapieplanning is the process of creating a radiotherapy treatment plan to deliver a prescribed radiation dose to a target volume while sparing surrounding healthy tissue. The goal is to achieve adequate tumor control while minimizing radiation-induced side effects. Planning integrates patient imaging, dose calculation, and optimization within a treatment planning system.

Imaging and delineation are central to planning. A CT simulation is typically acquired, often with MRI or PET fusion to improve target and organ-at-risk visualization. Immobilization devices are used to ensure reproducible positioning. Delineated contours commonly include the gross tumor volume (GTV), clinical target volume (CTV), planning target volume (PTV), and organs at risk (OARs). Margins account for motion and setup uncertainties.

Dose calculation and optimization involve selecting a planning technique and computing the dose distribution. Treatment planning systems use algorithms to optimize beam energies, angles, and shapes to meet dose constraints for targets and OARs. Evaluation uses metrics such as dose–volume histograms, conformity and homogeneity indices, and adherence to dose constraints across different fractions.

Delivery techniques and quality assurance ensure the plan can be safely executed. Methods include 3D-CRT, IMRT, VMAT, and SBRT/SRS. Plan verification and patient-specific QA checks validate dose delivery before treatment, and image-guided radiotherapy (IGRT) is often employed to verify setup and anatomy at each session. Motion management may be used for organs that move.

Workflow and teams typically involve a radiation oncologist, dosimetrist, medical physicist, and radiation therapists. The process spans simulation, contouring, planning, plan approval, QA, treatment, and follow-up, with potential adaptive steps when anatomy or physiology changes.