How does radiation intensity change with increasing distance from the source?

Related MCQs

• A radiographic exposure with 3700 GBq (100 Ci) source of Ir-192 using source to film distance of 60 cm results in a radiation intensity of 0.12 Gy/h (11.8 R/h) and a radiographic density of 2.5. The intensity of radiation needed to obtain the same density when the source to film distance is changed to120 cm is:
• If the radiation intensity is 5.9 Gy/h (590 R/h) at a distance of 30.5 cm (1 foot) from a source, how far is it to the point where the radiation intensity is 0.02 Gy/h (2R/h)?
• If the radiation intensity is 5 Gy/h (500 R/h) at a distance of 152.4 cm (5 feet) from a source, how far is it to the point where the radiation intensity is 0.05 Gy/h (5 R/h)?
• At 61 cm (two feet) from a radiation source, radiation intensity is 3 Gy/h (300 R/h). What is the Intensity at 244 cm (8 feet) from the source?
• If the radiation intensity is 5 Gy/h (500 R/h) at a distance of 152.4 cm (5 feet) from a source, what is the intensity at 1524 cm (50 feet)?
• If the radiation intensity is 1 Gy/h (100 R/h) at a distance of 152.4 cm (5 feet) from a source, what is the intensity at 610 cm (20 feet)?
• A good Cobalt-60 shot is made on a 7.6 cm (3 inches) steel casting using an exposure time of 10 minutes and a source-to-film distance of 91.5 (36 inches). If it is necessary to change the source-to-film distance to 61 cm (24 inches), what exposure time would produce a similar radiograph if all other conditions remain the same?
• The amount of X radiation or gamma radiation is often spoken of as the of the radiation:
• If an exposure time of 60 seconds and source to film distance of 365.7 m (1200 feet) is necessary for a particular exposure, what exposure time would be needed for an equivalent exposure if the source- to-film distance is changed to 457.2 m (1500 feet)?
• Source-to-object distance, object-to-film distance, and source size are the three factors that control the of the radiograph.