Abstract
Radiotherapy treatment plan evaluation relies on an implicit estimation of the tumor control probability (TCP) and normal tissue complication probability (NTCP) arising from a given dose distribution. A potential application of radiobiological modeling to radiotherapy is the ranking of treatment plans via a more explicit determination of TCP and NTCP values. Although the limited predictive capabilities of current radiobiological models prevent their use as a primary evaluative tool, radiobiological modeling predictions may still be a valuable complement to clinical experience. A convenient computational module has been developed for estimating the TCP and the NTCP arising from a dose distribution calculated by a treatment planning system, and characterized by differential (frequency) dose‐volume histograms (DDVHs). The radiobiological models included in the module are sigmoidal dose response and Critical Volume NTCP models, a Poisson TCP model, and a TCP model incorporating radiobiological parameters describing linear‐quadratic cell kill and repopulation. A number of sets of parameter values for the different models have been gathered in databases. The estimated parameters characterize the radiation response of several different normal tissues and tumor types. The system also allows input and storage of parameters by the user, which is particularly useful because of the rapidly increasing number of parameter estimates available in the literature. Potential applications of the system include the following: comparing radiobiological predictions of outcome for different treatment plans or types of treatment; comparing the number of observed outcomes for a cohort of patient DVHs to the predicted number of outcomes based on different models/parameter sets; and testing of the sensitivity of model predictions to uncertainties in the parameter values. The module thus helps to amalgamate and make more accessible current radiobiological modeling knowledge, and may serve as a useful aid in the prospective and retrospective analysis of radiotherapy treatment plans.PACS number: 87.53.Tf
Highlights
Radiotherapy treatment plans are assessed by evaluating the 3D dose distributions calculated by a treatment planning system
We have developed a convenient software tool for estimating the tumor control probability (TCP) or normal tissue complication probability (NTCP) arising from differential dose-volume histograms (DDVHs)
Included are two NTCP models: a sigmoidal dose response (SDR) model introduced by Lyman[9] and individualbased and population-based variants of the Critical Volume (CV) model; and two TCP models: a two-parameter Poisson-based model and a model employing linear-quadratic cell kill and the formalism developed by Zaider and Minerbo[8] to account for repopulation
Summary
Radiotherapy treatment plans are assessed by evaluating the 3D dose distributions calculated by a treatment planning system. The evaluation process includes the following: [1] looking at the dose distribution superimposed on images of the patient anatomy; and [2] examining dosevolume histograms (DVHs), which are 1D representations of 3D dose information, for each organ or tumor volume of interest. With these methods of assessment, acceptance or rejection of a plan relies on an implicit estimation of the tumor control probability (TCP) and normal tissue complication probability (NTCP) arising from the dose distribution. To determine the optimal plan in this case, clinicians may need to rely on relatively vague notions of dose-volume characteristics of different tissues
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
