Determination and Comparison of Radiation Absorbed dose to the Blood, by Applying Different Techniques, for Patients, Suffering from Differentiated Thyroid Cancer

BACKGROUND: Radiation absorbed dose to the red bone marrow, in the therapy of differentiated thyroid carcinoma (DTC) with 131I (radioiodine), cannot be measured directly. The absorbed dose to the blood seems to be a good first- order approximation of the radiation absorbed dose to the hematopoietic system and a better means to quantify exposure from therapy than the total amount of activity administered. OBJECTIVE: The aim of this research was to determine the radiation absorbed dose to the blood, for patients suffering from differentiated thyroid cancer. MATERIALS AND METHODS: Twenty seven patients, 22 women and 5 men, suffering from DTC were enrolled in this study. We applied four formulas and we compared between the estimated values of absorbed dose that were obtained by three formulas and those that obtained by fourth (standard one). RESULTS: All the values of absorbed dose that obtained by one of the techniques were regularly highly estimated, even though they have an excellent correlation (99%) with the standard value. CONCLUSIONS: Highly overestimated or highly underestimated results that can be obtained by certain method or technique are not desirable, because they tend to exaggerate, by increasing or decreasing, the radiation protection procedures. CONVERSION RADIATION UNITS: To convert the values of absorbed dose from S.I unit (mGy/MBq) to traditional unit (rad/mCi), we can simply multiply the values that expressed in S.I units by a factor of 3.7, and we don't need to apply complicated formulas, which were applied by other researches.