Author/Editor		Schinkel, Colleen; Stavreva, Nadia; Stavrev, Pavel; Carlone, Marco; Fallone, B Gino
Title		Functional form comparison between the population and the individual Poisson based TCP models
Translated title		Primerjava Poissonovih TCP modelov za posameznika in populacijo
Type		članek
Source		Radiol Oncol
Vol. and No.		Letnik 41, št. 2
Publication year		2007
Volume		str. 90-8
Language		eng
Abstract		In this work, the functional form similarity between the individual and fundamental population TCP models is investigated. Using the fact that both models can be expressed in terms of the geometric parameters gamma50 and D50, we show that they have almost identical functional form for values of gamma50 >= 1. The conceptual inadequacy of applying an individual model to clinical data is also discussed. A general individual response TCP expression is given, parameterized by Df and gammaf - the dose corresponding to a control level of f, and the normalized slope at that point. It is shown that the dose-response may be interpreted as an individual response only if gamma50 is sufficiently high. Based on the functional form equivalency between the individual and the population TCP models, we discuss the possibility of applying the individual TCP model for the case of heterogeneous irradiations. Due to the fact that the fundamental population TCP model is derived for homogeneous irradiations only, we propose the use of the EUD, given by the generalized mean dose, when the fundamental population TCP model is used to fit clinical data.
Summary		Raziskali smo podobnost TCP modelov za posameznika in populacijo. Z ozirom na to, da lahko oba modela opišemo z geometrijskima parametroma gama50 in D50, smo pokazali, da dobita skoraj enako obliko pri vrednostih gama50 >= 1. Obravnavali smo neprimernost uporabe modela za posameznika na kliničnih podatkih. Podali smo splošen izraz za TCP in ga parametrizirali z Df in gamaf - z dozo, kjer TCP zavzame vrednost f in z normaliziranim naklonom v tej točki. Izkazalo se je, da lahko krivuljo interpretiramo kot odziv posameznika le ob dovolj velikem gama50. Na osnovi podobnosti TCP modelov za posameznika in populacijo smo obravnavali možnost uporabe slednjega v primeru neenakomernega obsevanja. Ker osnovni TCP model za populacijo predpostavlja enakomerno obsevanje, smo predlagali, da se pri uporabi na kliničnih podatkih vrednost parametra EUD izenači s povprečno dozo.
Descriptors		RADIOTHERAPY DOSAGE POISSON DISTRIBUTION DOSE-RESPONSE RELATIONSHIP, RADIATION MODELS, STATISTICAL