calculation of thyroid dose with planner system and evaluation of thyroid function after radiotherapy for patients with breast cancer

background: much research has widely been conducted into thyroid hormones levels following radiotherapy for breast cancer. consequently, in this study, we evaluated to relate the rate of thyroid hormones levels with the dose distribution among breast cancer patients. material and methods: thirty patients were treated with 4-field breast cancer radiotherapy. the dose volume histograms, the volume percentage of the thyroid absorbing respectively 20, 30, 40 and 50 gy were then estimated (v20, v30, v40 and v50) together with the individual average thyroid dose over the whole gland derived from their computed tomography-based treatment plans. then, in serum samples triiodothyronine [t3], thyroxine [t4], thyroid-stimulating hormone [tsh] of the patients were measured before and after radiotherapy. results: there were no significant differences in thyroid hormones levels before and after radiotherapy for patients with breast cancer (p value >.05). conclusion: on the balance, we understood that thyroid stimulating hormones levels did not change before and after cancer breast radiotherapy.