Keywords: Monte Carlo simulation, diagnostic radiology, thermoluminescent dosimetry, TLD, radiation dose, radiodiagnostic examinations, radiation exposure, low radiation
The evaluation of the dose equivalent to the people accompanying patients in diagnostic radiology using the MCNP4C Monte Carlo code and TL dosimetry
The general purpose Monte Carlo N-Particle Radiation Transport Computer Code (MCNP4C) was used to calculate the equivalent dose to the person or people accompanying patients who have been exposed to radiation that was scattered from the patient. To do the calculations, two homogeneous water phantoms were used to simulate the patient and the accompanying person. Finally, in the case of source specification, only the focus of the X-ray tube was modelled, i.e., as a standard MCNP point source that emits a cone of photon. The X-ray spectra to be used in the MCNP simulations were generated with spectrum generating software. These calculations were done for different patient sizes and radiological operations. Dose measurements were made using standard methods that employ LiF TLD-100 dosimeters. A Thermoluminescent Dosimetry (TLD) card was placed on the main trunk of the body of the accompanying person(s), where the maximum dose was probable. In the case of TLD, for a group of 100 examinations, the dose equivalents ranged from 0.01 μSv to 0.13 mSv, with an average of 0.05 mSv. These results are seen to be in close agreement with Monte Carlo simulations. The results suggest that under the correct technical conditions, the radiation doses that are received by the accompanying person or people in radiodiagnostic examinations can be limited to acceptable values and can certainly be under the limits of a permissible dose to the public (1 mSv per year). However, if exposure is frequently repeated, it is probable that the limits that were mentioned above will be exceeded.