The use of the normal tissue non-complication probability (NTCP0) methodology as a new alternative of assessing side-effects in brachytherapy treatments

BACKGROUND: The NTCP methodology evaluating side-effects (S-Es) was initially used in radiotherapy (RT), and later was extended to brachytherapy (BT). The NTCP0 methodology has been recently introduced in RT. Given the advantages, this methodology could replace NTCP. MATERIALS AND METHODS: Revisions of studies related to use of NTCP in the evaluations of S-Es in BT. Development of the first versions of two Matlab applications of the NTCP0 methodology. These applications have three options. Two of them employ the well-known aspects of a phenomenological model, or the probabilistic relationship between NTCP0 and total NTCP (TNTCP) that is the sum(NTCP(x(i))) i: i(th) complication i:1..nc: Number of complications; where NTCP0 = 100% — TNTCP; and the third option assumes a NTCP(x(i)) discrete probabilistic distribution generated by the binomial distribution, where one of its parameters is automatically obtained from a databased of the Disease locations Vs. Late complications. RESULTS: The NTCP0cal and NTCP0calDr Matlab applications have been developed, and respectively used for fractional continuous low dose-rate BT. CONCLUSIONS: NTCP0 is defined as the ratio of the number of patients without acute/late complications and total of them, and also can be obtained using our Matlab applications. NTCP0 works do not disregard the last 10–15 years of NTCP research; but NTCP0 was not considered during these years. A generic example was used for showing the variations of the late complications and NTCP0 for a BT treatment of a constant number of fractions and six different dose per fraction values.