Effects of Distance and Radiation Dose Scattering from Mobile X-ray Machines used in Hospitals in Bangkok, Samut Sakhon, and the 4th Health Service Area

Effect of Distance and Radiation Dose Scattering from Mobile X-ray Machines

Abstract

    Mobile X-ray machines are used to take pictures of immobile patients, which has amount of radiation exposure depends on the radiographic time, distance and technical settings. If the scatteredness of radiation is high, it will affect the health of the radiation recipient. The objective of this study was to study the effect of distance on the degree of scatteredness of radiation doses and the scatteredness characteristics at 80 kVp and 32 mAs of radiographic setting. The study was carried out among mobile X-ray machines used in hospitals in Bangkok and 6 provinces in the 4^th Health Service Area and Samut Sakhon province in the 5^th Health Service Area, with a total of 83 X-ray machines (7 brands, 15 models) with a fixed radiographic technique value of 80 kVp and 32 mAs. The tested mobile X-ray machines had degree of scatteredness (mean±SD) at a distance of 1 meter ranged from 2,100±1,253 μSv/hr to 11,500±9,192 μSv/hr, and when tested at a distance of 2 meters, the degree of scatteredness was reduced to the range of 800±0 μSv/hr to 2,940±3,624 μSv/hr, while the tests at 3, 4 and 5 meters showed a significant decrease in degree of scatteredness, which were in the range of 256±0 μSv/hr to 1,278±1,021 μSv/hr, 131±78 μSv/hr to 719±575 μSv/hr and 84±50 μSv/hr to 449±387 μSv/hr, respectively. When comparing the degree of scatteredness with the measured distance, the results showed that the degree of scatteredness decreased with the distance measured in all machines, and the degree of scatteredness had an exponential reduction pattern. The results also pointed out that at a distance of 2 meters or more, the scatteredness value did not exceed the individual dose limit for radiation workers. In conclusion, the mobile X-ray operation should be carried out at least 2 meters away from the X-ray machine. However, the distance from the X-ray machine should be as far as possible when performing imaging work with any mobile X-ray machines.