Evaluation of X-ray absorbed dose in thyroid during CXR imaging of the chest by Monte Carlo simulation (DOSXYZnrc)

Abstract:   Introduction: Chest radiography is one of the most common X-ray imaging procedures performed worldwide. During this process, in addition to the chest, other tissues, including the thyroid, are also exposed to radiation. Due to the fact that one of the most important risk factors for thyroid cancer is ionizing radiation, measuring the absorption of X- rays in the thyroid is of special importance.  Method: Energies of 100, 70 and 80 kV were used in the Monte Carlo code. 300 million particles were used in the BEAMnrc simulation and 100 million particles in the DOSXYXnrc simulation Then, using chest CT scan images obtained from patients, the chest phantom was designed by CTCREATE method.  The dose absorbed in the thyroid gland was calculated using BEAMdp from the output obtained from BEAMnrc. Results: D / Dmax was obtained in different coordinates from 0.54 to 6.91 and the calculation error was calculated from 0.32 to 18.73%. Discussion and Conclusion: Chest radiography can lead to high dose absorption in some areas of thyroid tissue. Dose absorption in thyroid is present in all energy ranges, which is typically done on chest radiographs.