PPT Slide
- Inverse Square Law & Distance
- When you double your distance from the table, you reduce your exposure by 1/4. For example, when the exposure 1 ft. from the table side is 100 mR/hr, then the exposure 4 feet away will be 1/16 or 6.25 mR/hr there.
- The same is true when you move the patient further from the X-ray tube. For example, at 50 cm. the dose may be 5 R/min., but at 60 cm the dose would be 3.5 R/min. (a 30% reduction in this case)