Comment on “Simulating Radiotherapy Effect in High-Grade Glioma by Using Diffusive Modeling and Brain Atlases”

الملخص EN

The paper by Roniotis et al.

[1] contains a serious error.

The problematic term is f ( c ) representing the effect of radiotherapy on the tumor (equation (11) page 4).

This term is inserted in the reaction-diffusion (Fisher-Kolmogorov) equation (3), describing the expansion-infiltration of brain tumors.

As is well known, in a mathematical expression, adding (or subtracting) two terms with different dimensions is invalid (e.g., what would be the result obtained by adding a length with an area?).

That is exactly what has been done in equation (11), first line, that we rewrite here, adding square brackets for greater clarity: 11 f c = ρ - 1 - e - a · R t - b · R t r t · c · c m - c c m , t ∈ therapy.

The term included in the curved brackets is a simple number (i.e., dimensionless), but ρ has the dimensions of 1/time and represents the tumor expansion rate.

Therefore one cannot subtract the (1 – exponential) term from ρ .

It is probable that all the subsequent results are erroneous (in particular Figure 2 ).