3D conformal radiotherapy and IMRT are generally only possible for patients who have received CT-simulation. 3D-conformal radiotherapy and IMRT have similar goals: that is to ensure the target (the cancer) gets the appropriate dose of radiation, whilst ensuring that critical normal tissues receive low or no dose of radiation. 3D-conformal radiotherapy is considered appropriate for most patients, although IMRT is particularly recommended for patients with prostate, brain and head and neck cancer.
The benefits of IMRT can be seen in the following patient with prostate cancer. One can see the high dose volume of conventional 6-field 3D conformal radiotherapy (on the right) is good, with a small high dose area (shaded). 6-field 3D-conformal radiotherapy should be the basic treatment offered, although some centres still use a 4-field technique which most would consider to be inferior.
However on the left is an IMRT field, which has an even better dose distribution, and really is the treatment of choice for prostate cancer. IMRT should be used in conjunction with CT-simulation, PET-planning, or MRI-CT simulation (in the case of prostate, brain and head and neck cancers).
