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To encourage the use of the NTCP0 for evaluating safety as a new alternative of assessing the S-Es of the radiation oncology treatments; and the use of the 'NTCP0cal' methodology that calculates/estimates NTCP0. Revisions of studies related to use of the NTCP in the evaluations of S-Es. Development of the first version of the Matlab application of our methodology, which provides three options, two of them employ the well-known aspects of a phenomenological model, or the relationship with the TNTCP; where NTCP0 = 100%-TNTCP; and the third option determines NTCP0 from an assumed NTCP discrete probabilistic distribution from the binomial distribution, where one of its parameters is automatically defined from a database d of the Disease locations Vs. Late complications. As result of revisions of some QUANTEC studies, we can say that: (1) The majority of current NTCP models are DVH-based; (2) The risk of toxicity is the way of evaluating the S-Es of the radiation oncology treatments; and (3) The NTCP are used mainly for evaluations of individual or principal complications or Endpoints of the radiation treatments. The 'NTCP0cal' Matlab application developed in this study has three calculation options. Two of the options provide additional graphical information about the distributions. The NTCP0 is a new radiobiological concept, its introduction let to correct some current P + and UTCP formulations, and will allow evaluating S-Es in whatever activity involving ionizing radiation, like radiation treatments; and its phenomenological model function of dose prescribed (D = n*d) will allow calculating values of NTCP0 for a range of dose per fraction (d) in a treatment with a determined number of fractions (n), or for range of n for a constant d. The DVH is irrelevant for this model. For whatever radiation treatment given to a population of similar patients under similar circumstances, the NTCP0 is calculated as ratio of the number of patients without acute/late complications and total of them. When this number is unknown, then NTCP0 can be obtained using the 'NTCP0cal' application. [ABSTRACT FROM AUTHOR]

Although in the ionizing radiation field many concepts and processes are currently recognized as radiobiological, there are also probabilistic ones, and a probabilistic treatment makes a better understanding about them. The purpose of this study is to develop a new radiobiological simulator that calculates the tumor control probability (TCP) for a tumor heterogeneously irradiated from a fractioned treatment. The three possible types of cells and the results of interactions of ionizing radiation with each cell of a determined volume are analyzed. For an irradiated region with a dose per fraction d, the simulator determines the radiation biological effects using the cell kill (K) and cell sub-lethal damage, volume, cell density, cell repair of damaged cells during the interfractions, and number of fractions. K is determined from its probabilistic complement, the cell survival (S), described with the linear-quadratic (LQ) S(d) model as K = 1 − LQ S (d). TCP is calculated from computational simulations as in the ratio of simulations with K = 100% and their total. This application opens new avenues for theoretical and experimental investigations concerning simulations of radiation treatments, and methodologies for therapy optimizations. Our simulator represents a novel methodology as TCP is calculated without analytical formulas, but based on its own probabilistic definition. [ABSTRACT FROM AUTHOR]

1) To show the validation criteria of the product of probabilities (PPs). Bayes' theorem (BT) is widely used in the ionizing radiation field; and 2) To demonstrate that terms P(B|A) and P (A|B) in the BT are not new probabilistic metrics, but the own respective probabilities of B and An events. Mathematical derivations based on strong probabilistic foundations, and with their respective illustrations. a) Determination of the validationcriteria of the PPs; and b) There is demonstration of incoherencies of the BT. 1) The tumor control probability (TCP) of independent radiation oncology treatments to patients with more than one target, calculated as the product of individual TCPs is an incoherent determination; 2) Given previously explained about BT terms, the use of this theorem should be re-considered; and 3). P (A∩B) P(A)*P(B) only when N × P(A) and N × P(B) are a subset of a population N, and if A and B are independent and simultaneous events. • It provides validation criteria of the product of probabilities (PPs). • The use of the Bayes' theorem should be re-considered. • UTCP = TCP × NTCP0 is an excellent example using PPs. • It provides a new proposal for the composite TCP expression. [ABSTRACT FROM AUTHOR]