بررسي تاثير دما بر دوز جذبي در راديوتراپي

Effect of Temperature on the absorbed dose in radiation therapy

Objective: Radiotherapy is one of the methods used in cancer treatment. In this method tumor cells are exposed to ionizing radiation to kill these cells. More of tumor cells are killed if exposed more radiation within the region of tumor. However, the main purpose of radiotherapy is exposing enough doses to tumor mass yet protecting the normal tissues around it. In this study, we investigate the effect of temperature on the absorbed radiation dose. Materials and Methods: In these experiments a 30 ×30 × 30 cm water phantom, Farmer ionization chamber and related electrometer were used to measure the effects of exposing γ_radiation of Co-60. The field size was varied for (5×5 cm2 to 20×20 cm2) with depths (5 to 9 cm) and the range of temperatures (30 to 50 °C). The curves for variation of absorbed dose at different depth at different temperatures were drawn and a temperature enhancement ratio (TER) was introduced. Results: Our results showed that TER increases for all field sizes and depths with increase in temperature. A pronounced effect was observed at temperatures higher than 42 °C. Conclusion: These findings suggest that the hyperthermia (above 42 °C), caused a sudden variation of the structure of water and increased the absorption of radiation dose.