Computational study of necrotic areas in rat liver tissue treated with photodynamic therapy.

•The necrotic area can be equal up to 155.3% of beam's radius.•High values of light fluence rate (φ) increase necrotic distance.•High φ values are necessary to maintain clinically applicable irradiation times.•Irradiation time is independent of φ for the necrosis of upper tumor layers.•A novel calculation algorithm of necrotic areas in photodynamic therapy (PDT).