ABSTRACT
The principal aim of radiotherapy is to give a tumoricidal dose to the cancer-bearing tissue and to minimize the dose to normal healthy tissue. Given the dose response function of the tumor and the healthy tissue, the requirement stated in the ICRU report 50 (International Commission on Radiation Units and Measurements Report 50, 1993) is to apply the dose to the tumor within −5% and 7% of the prescribed dose. A detailed analysis of uncertainties associated with radiation treatment shows that 3% accuracy is required in the dose calculation to yield ±5% accuracy in the dose delivered to the patient (International Commission on Radiation Units and Measurements Report 24, 1976; Brahme, 1984; Dutreix, 1984; Van Dyk et al., 1993). Some studies have even concluded that for certain types of tumors the uncertainty in dose delivery should be smaller than 3.5% (Brahme, 1984; Mijnheer et al., 1987, 1989), which in turn means that the clinically implemented dose calculation algorithm should be accurate within ±2%. Thus, accurate dose calculation algorithms for treatment planning systems are of critical importance in radiation therapy.
