Investigation of acoustic radiation force for radio-protecting normal tissues during radiation therapy.

Radiation therapy (radiotherapy) is the medical use of ionizing radiation as part of cancer treatment to erradicate malignant cells. Normal tissue tolerance is currently a major dose-limiting factor. As molecular oxygen plays a critical role in creating the radiation damage, we propose a novel approach, that is, the use of acoustic radiation force (ARF) to suppress the normal tissue oxygenation, for the purpose of protecting the normal tissue and increasing its tolerance during radiotherapy. This paper investigated the effects of ARF on tissue oxygenation. Both subcutaneous tissue and tumor were studied for comparison. Experiments have been carried out using a murine model. Preliminary results showed that ARF can effectively suppress normal tissue oxygenation, and at the same time had negligible effect on the tumor oxygenation. Further investigation is ongoing to characterize the time course of oxygen changes with different ultrasound parameters (frequency, intensity, ultrasound pulse duration, etc.), for the purpose of optimal control of tissue oxygenation.