Radiation Treatment Planning

In radiotherapy, radiation treatment planning is the process in which a team consisting of radiation oncologists, radiation therapist, medical physicists and medical dosimetrists plan the appropriate external beam radiotherapy or internal brachytherapy treatment technique for a patient with cancer.

Typically, medical imaging (i.e., x-ray computed tomography often the primary image set for treatment planning, magnetic resonance imaging excellent secondary image set for soft tissue contouring, and positron emission tomography less commonly used and reserved for cases where specific uptake studies can enhance planning target volume delineation) are used to form a virtual patient for a computer-aided design procedure. Treatment simulations are used to plan the geometric, radiological, and dosimetric aspects of the therapy using radiation transport simulations and optimization. For intensity modulated radiation therapy (IMRT), this process involves selecting the appropriate beam energy (photons, and perhaps protons), energy (e.g. 6 MV, 18 MV) and arrangements. For brachytherapy, involves selecting the appropriate catheter positions and source dwell times (in HDR brachytherapy) or seeds positions (in LDR brachytherapy). The more formal optimization process is typically referred to as forward planning and inverse planning. Plans are often assessed with the aid of dose-volume histograms, allowing the clinician to evaluate the uniformity of the dose to the diseased tissue (tumor) and sparing of healthy structures.

Today, treatment planning is almost entirely computer based using patient computed tomography (CT) data sets. Modern treatment planning systems provide tools for multimodality image matching, also known as image coregistration or fusion.