Radiation burden of patients outside the target volume in special irradiation treatment techniques

Novel special irradiation techniques in radiation therapy, notably IMRT and STRCH, expose the patients to increased amounts of radiation (by orders of magnitude in some instances) mainly outside the planned therapeutic volume. Where a treatment dose of 50-70 Gy is planned in fractionated therapy, the patient's burden in this area is at the level of units of Gy despite the fact that the system is equipped with an extra collimating system to absorb this unwanted radiation. The aim of the study was to assess the patient's radiation burden employing a real plan for IMRT techniques as well as for stereotactic radiosurgery, using cylindrical collimators and a micro MLC attached to the original collimating system. (orig.)