# On an inverse source problem for the full radiative transfer equation with incomplete data

## TL;DR

This paper introduces a novel numerical method for solving an inverse source problem in the radiative transfer equation with incomplete data, using a boundary value reformulation and quasi-reversibility, with proven convergence and demonstrated robustness.

## Contribution

The paper develops a new numerical approach that does not require restrictive assumptions on coefficients, employing a boundary value reformulation and discrete Carleman estimates for convergence.

## Key findings

- Method effectively handles noisy data
- Proven convergence of regularized solutions
- Numerical simulations show high accuracy

## Abstract

A new numerical method to solve an inverse source problem for the radiative transfer equation involving the absorption and scattering terms, with incomplete data, is proposed. No restrictive assumption on those absorption and scattering coefficients is imposed. The original inverse source problem is reduced to boundary value problem for a system of coupled partial differential equations of the first order. The unknown source function is not a part of this system. Next, we write this system in the fully discrete form of finite differences. That discrete problem is solved via the quasi-reversibility method. We prove the existence and uniqueness of the regularized solution. Especially, we prove the convergence of regularized solutions to the exact one as the noise level in the data tends to zero via a new discrete Carleman estimate. Numerical simulations demonstrate good performance of this method even when the data is highly noisy.