Exposures in interventional radiology using Monte Carlo simulation coupled with virtual anthropomorphic phantoms.

In this work we investigated the way in which conversion coefficients from air kerma-area product for effective doses (CCE) and entrance skin doses (CCESD) in interventional radiology (IR) are affected by variations in the filtration, projection angle of the X-ray beam, lead curtain attached to the surgical table, and suspended shield lead glass in regular conditions of medical practice. Computer simulations were used to model an exposure scenario similar to a real IR room. The patient and the physician were represented by MASH virtual anthropomorphic phantoms, inserted in the MCNPX 2.7.0 radiation transport code. In all cases, the addition of copper filtration also increased the CCE and CCESD values. The highest CCE values were obtained for lateral, cranial and caudal projections. In these projections, the X-ray tube was located above the table, and more scattered radiation reached the middle and upper portions of the physician trunk, where most of the radiosensitive organs are located. Another important result of this study was to show that the physician's protection is 358% higher when the lead curtain and suspended shield lead glasses are used. The values of CCE and CCESD, presented in this study, are an important resource for calculation of effective doses and entrance skin doses in clinical practice.

Comparison of point, line and volume dose calculations for exposure to nuclear medicine therapy patients.

This work compared the predicted dose to an individual due to exposure from a radioactive patient using three models (point, line, and volume), for three therapeutic regimens (hyperthyroidism, thyroid cancer, and non-Hodgkin's lymphoma). For the volume source calculations, Monte Carlo simulations employing the Visual Monte Carlo (VMC) code and the voxel phantom FAX were used. For hyperthyroid patients, the point, line, and volume source models predicted doses to exposed individuals of 54, 24, and 14 mSv, respectively, at a distance of 0.3 m, and 4.8, 4.0 and 3.3 mSv at a distance of 1 m. For thyroid cancer patients, the dose values were 85, 38, and 18 mSv at 0.3 m, and 7.6, 6.4, and 4.4 mSv at 1 m, respectively. For non-Hodgkin's lymphoma (NHL) subjects, the doses were 230, 103, and 36 mSv at 0.3 m, and 21, 17, and 10 mSv at 1 m. These results show that patient release based on point source calculations involves unnecessary conservatism.

Use of a voxel phantom as a source and a second voxel phantom as a target to calculate effective doses in individuals exposed to patients treated with 131I.

UNLABELLED: In this study, the Visual Monte Carlo radiation transport code and the female voxel phantom FAX were used to calculate organ and effective doses delivered by target-source irradiation geometries associated with radioiodine therapy treatments. METHODS: Specific situations were considered: when a patient was accompanied during hospitalization, when a patient was accompanied on return to his or her residence, and when a patient received daily care at home. RESULTS: This simulation study showed that, in the 3 situations considered, the total effective dose to an individual in normal contact with the patient was less than 0.85 mSv for up to 11.1 GBq (300 mCi) of administered activity. CONCLUSION: The results of this study suggest that for these patients receiving radioiodine therapy, radiation protection procedures after hospital discharge are unnecessary.