Implementation of the microdosimetric kinetic model using analytical microdosimetry in a treatment planning system for proton therapy.

Purpose: To implement RBE calculations in treatment planning systems based on the Microdosimetric Kinetic Model (MKM) upon analytical calculations of dose-mean lineal energy (y). MKM relies on the patterns of energy deposition in sub-nuclear structures called domains, whose radii are cell-specific and need to be determined.

Methods And Material: The radius of a domain (r) can be determined from the linear-quadratic (LQ) curves from clonogenic experiments for different cell lines exposed to X-ray and proton beams with known y.

Clinical implications of variable relative biological effectiveness in proton therapy for prostate cancer.

Purpose: To study the potential consequences of differences in the evaluation of variable versus uniform relative biological effectiveness calculations in proton radiotherapy for prostate cancer.

Methods And Material: Experimental data with proton beams suggest that relative biological effectiveness increases with linear energy transfer. This relation also depends on the ratio, characteristic of a tissue and a considered endpoint.

On the concepts of dose-mean lineal energy, unrestricted and restricted dose-averaged LET in proton therapy.

To calculate 3D distributions of microdosimetric-based restricted dose-averaged LET (LETd) and dose-mean lineal energy ([Formula: see text]) in order to explore their similarities and differences between each other and with the traditional unrestricted LETd. Additionally, a new expression for optimum restricted LETd calculation is derived, allowing for disregarding straggling-associated functions in the classical microdosimetric theory. Restricted LETd and [Formula: see text] for polyenergetic beams can be obtained by integrating previously developed energy-dependent microdosimetric functions over the energetic spectrum of these beams.

Is there a role for arcing techniques in proton therapy?

Proton arc therapy (PAT) has been proposed as a possible evolution for proton therapy. This commentary uses dosimetric and cancer risk evaluations from earlier studies to compare PAT with intensity modulated proton therapy. It is concluded that, although PAT may not produce better physical dose distributions than intensity modulated proton therapy, the radiobiological considerations associated with particular PAT techniques could offer the possibility of an increased therapeutic index.

Calculation of clinical dose distributions in proton therapy from microdosimetry.

Purpose: To introduce a new algorithm-MicroCalc-for dose calculation by modeling microdosimetric energy depositions and the spectral fluence at each point of a particle beam. Proton beams are considered as a particular case of the general methodology. By comparing the results obtained against Monte Carlo computations, we aim to validate the microdosimetric formalism presented here and in previous works.