Abstract
This paper describes measurements of external gamma radiation dose rate from terrestrial gamma-rays 1
m above the ground in three different mountainous locations in the western region of the Kingdom of Saudi Arabia. These locations are At-Taif city, Al-Hada village, and Ash-Shafa village. CaSO
4:Dy (TLD-900) thermoluminescent dosimeters were used for the detection of terrestrial gamma radiation at 40 different places in the three locations. The values of terrestrial gamma radiation dose rate measured ranged between 14 and 279
nGy
h
–1 for the time interval from June 2001 to June 2002. The measured dose rate varied with the season of the year. The average gamma radiation dose rates were 468, 541, and 781
μGy
y
–1 for At-Taif city, Al-Hada village, and Ash-Shafa village, respectively. The corresponding average absorbed doses to the population of the three locations were 328, 379, and 547
μSv
y
–1, respectively. The quality factor of 0.7
Sv
Gy
−1 was applied in the calculations of the absorbed dose to humans.