3D Conformal Radiation
3D conformal radiation is a process whereby the target for radiation is created as a three dimensional structure. This process may use one or more types of 3D imaging including CAT scans, PET scans or MRI scans. The target is contoured (outlined) on many axial slices of the body and the computer takes all of these separate axial contours and assembles the slices into a 3D structure. The same process is used to create 3D maps or structures of adjacent normal body parts.
After the structures have been created (targets and avoidance structures), the scan data is sent to radiation treatment planning computers. Specialized software is used by physicists and dosimetrists to arrange multiple beams of radiation which provide uniform coverage of the targets. The distribution of the radiation to the targets and avoidance structures is viewed in graphic analysis which is termed dose-volume histograms.
A more modern and more sophisticated type of 3D radiation is called intensity modulated radiation (IMRT). Almost all cases of 3D radiation now incorporate IMRT in the planning and delivery of the radiation.
Radiation can be used with several goals. For the goal of cancer cure, 3D or IMRT is usually used. Often radiation is used for improvement of symptoms with the goal of cancer cure. This goal is commonly called palliation. Palliative radiation may be used to reduce pain, control bleeding, reduce pressure on spinal cord or nerves, and improve obstruction on normal structures such as bronchial tube, ureter, kidney, and bowel.