Thermal‑Light Mix in Tumor Treatment: A New Computer View

Researchers have built a computer model that shows how light, heat and chemical reactions work together when treating cancer with a dye called indocyanine green (ICG). The model uses a fast Monte‑Carlo method on graphics cards to trace how 808‑nanometer laser light moves through a three‑dimensional tumour made of small cubes. As the light is absorbed, it heats the tissue and triggers chemical reactions that produce reactive oxygen species (ROS), which can kill cancer cells. The heat and ROS are linked to equations that describe how temperature, oxygen, and chemicals change over time. The simulated tumour is split into two regions: a low‑oxygen core and an outer layer where cells grow quickly. Light intensity drops sharply, losing about 70 % within the first 400 micrometres.Temperature peaks vary from roughly 41 °C to 54 °C depending on how long each laser pulse lasts. The outer, oxygen‑rich layer generates more ROS than the inner core, so it experiences stronger chemical damage. Heat alone can cause cell death (necrosis) in the core when pulses are strong enough, while ROS mainly triggers programmed cell death (apoptosis) in the outer region. A sensitivity test shows that pulse length, how fast oxygen moves through tissue, and the dye’s light‑absorbing power are the biggest factors that change how well the treatment works. This multiphysics approach lets scientists predict which parts of a tumour will respond best to the laser and helps them fine‑tune treatment settings before using real patients. Because it is based on physical laws, the model indicates trends rather than exact biological outcomes.