Optimization of Combined Radiation and Gold Nanoparticle Hyperthermia Therapy for Treating Cutaneous Squamous Carcinoma
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Radiation therapy offers the ability to kill and shrink tumors non-invasively and serves as adjuvant therapy post-surgery and as primary therapy for patients unable to undergo surgery. But the process is nonspecific and nearby healthy tissue exposed to the radiation can also undergo the same ablation process that kills tumor cells. A possible solution is coupling the radiation therapy with directed hyperthermia. Tumors exposed to elevated temperatures of 40-45C during hyperthermia exhibit increased sensitivity to radiation therapy and are more likely undergo ablation. The heating process of the tissue can be controlled by directly injecting the tumor with gold nanoparticles (AuNPs), which can absorb near infrared light and heat the tumor faster. This project models the treatment of subcutaneous squamous carcinoma using AuNP controlled hyperthermia and X-ray radiation therapy. Using COMSOL Multiphysics 4.3b using 2D axisymmetric coordinates, we simplified the geometry of the tumor and surrounding tissue. We modeled two overall processes vital to the treatment: diffusion of AuNPs injected into the tumor and the heating process of hyperthermiaradiation therapy. We optimized the heating and radiation dosage combination for maximized tumor death and minimized tissue damage. Survival fraction of tumor and tissue were evaluated using a linear quadratic model of radiation dosage modified for thermal treatments. Our model shows the results for AuNPs diffusion and hyperthermia-radiation tissue ablation. The optimized combination of hyperthermia and X-ray dosage was determined to be 60 seconds of heating using a 1.5 W/cm2 infrared lamp and 0.35 Gy. This hyperthermia and radiation dosage model takes advantage of AuNP’s ability to increase tumor sensitivity to radiation therapy. By optimizing the heating time and radiation dosage combination, we can reduce the total radiation exposure and the length of treatment, allowing for overall faster and less harmful treatments for patients.