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WE‐C‐BRA‐02: Parameters for and Use of NTCP Models in the Clinic
Author(s) -
Yorke E
Publication year - 2007
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2761533
Subject(s) - medical physics , radiation treatment planning , radiation therapy , presentation (obstetrics) , computer science , set (abstract data type) , dosimetry , medicine , nuclear medicine , surgery , programming language
Delivery of adequate tumor dose without causing excessive normal tissue complications is the driving principle of modern radiation therapy. Resulting dose distributions in normal tissues are very different from the “partial organ irradiation” distributions that characterize the simple beam arrangements of earlier days. Further, the growing popularity of hypofractionation drastically widens the range of biological effective doses within organs at risk (OAR). The clinical physicist is faced with uncertainty as to what aspects of an OAR dose distribution require special consideration in treatment plan design and evaluation. Normal tissue complication probability (NTCP) models are one way to account for the full dose distribution. For most serious toxicities, statistical models from various outcomes analyses help direct the planner toward dose‐volume limits. There are also several semi‐mechanistic models, each with a set of parameters that must be adjusted to describe existing data. But for conditions that differ greatly from those under which they were ‘commissioned’, two models for the same endpoint and starting from the same input dose distribution do not necessarily predict the same NTCP. A working group, with joint participation from AAPM, ASTRO and RTOG, is being established to, among other things, reconcile model differences and provide clinical guidelines in the near future. In this presentation, common NTCP models for several major dose‐limiting toxicities will be described, including parameters sets gleaned from literature review. Problems and pitfalls of integrating and interpreting diverse studies and applying them to an individual clinic's practice will be discussed and real‐world examples of application to clinical decisions will be presented. Educational Objectives: 1. Understand the important features of the most widely‐used NTCP models. 2. Understand how the model parameters affect predictions of normal tissue dose‐volume responses. 3. Understand some of the complexities of implementing these models into routine clinical practice.