Radiobiologically equivalent deformable dose mapping for re-irradiation planning: Implementation, robustness, and dosimetric benefits.

Background: Re-irradiation in radiotherapy presents complexities that require dedicated tools to generate optimal re-treatment plans. This study presents a robust workflow that considers fractionation size, anatomical variations between treatments, and cumulative bias doses to improve the re-irradiation planning process.

Methods: The workflow was automated in MIM® Software and the Elekta© Monaco® treatment planning system.

Development of a multi-layer quality assurance program to evaluate the uncertainty of deformable dose accumulation in adaptive radiotherapy.

Purpose: Deformable dose accumulation (DDA) has uncertainties which impede the implementation of DDA-based adaptive radiotherapy (ART) in clinic. The purpose of this study is to develop a multi-layer quality assurance (MLQA) program to evaluate uncertainties in DDA.

Methods: A computer program is developed to generate a pseudo-inverse displacement vector field (DVF) for each deformable image registration (DIR) performed in Accuray's PreciseART.

Incorporating uncertainty bounds in daily deformable dose accumulation for adaptive radiation therapy of head-and-neck cancer.

Background: The widespread use of deformable dose accumulation (DDA) in adaptive radiotherapy (ART) has been limited due to the lack of clinically compatible methods to consider its related uncertainties.

Purpose: We estimate dose reconstruction uncertainties in daily DDA during CT-guided radiotherapy of head-and-neck cancer (HNC). We project confidence intervals of cumulative dose-volume parameters to the parotids and determine threshold values to guide clinical decision-making in ART.

Experimental HPGe coaxial detector response and efficiency compared to Monte Carlo simulations.

The peak efficiency for photons hitting the frontal surface of a medium volume n-type HPGe coaxial detector is mapped using acutely collimated beams of energies between 31 and 383 keV from a (133)Ba radioactive source. Simulated values obtained with the Monte Carlo radiation transport code penelope, using a model that respected actual detector dimensions and physical constants while varying dead-layer thicknesses, allowed us to fit the experimental results in the detector bulk but not near its rim. The spectra of a (137)Cs source were measured using the detector shielded from the natural background radiation, with and without a broad angle collimator.