Question

If a tech absorbs a dose rate of 2.5 mrem/hr while working 3 ft from a therapy patient, what distance will need to be maintained in order to absorb only 2 mrem/hr?

a. 2.5 ft
b. 3.4 ft
c. 4.0 ft
d. 4.2 ft

Answer 1

To reduce the dose rate from 2.5 mrem/hr to 2 mrem/hr, the technician must increase their distance from the patient to approximately 3.4 ft, calculated using the inverse square law.

Step-by-step explanation:

The question presented deals with the principles of radiation safety, specifically the inverse square law related to radiation protection. The inverse square law states that the intensity of radiation decreases with the square of the distance from the source. Given that a technician receives a dose rate of 2.5 mrem/hr at 3 ft from a therapy patient, we can use the inverse square law to determine the distance needed to reduce the dose rate to 2 mrem/hr.

To solve this, we can set up a proportion using the distances and respective dose rates:

(Dose rate 1 / Dose rate 2) = (Distance 2 / Distance 1)²

(2.5 mrem/hr / 2 mrem/hr) = (Distance 2 / 3 ft)²

Then solve for Distance 2:

(5/4) = (Distance 2 / 3 ft)²

Distance 2 = 3 ft * sqrt(5/4)

Distance 2 = 3 ft * (sqrt(5)/2)

Distance 2 ≈ 3.354 ft, which rounds to 3.4 ft

Therefore, to absorb a dose rate of 2 mrem/hr, the technician would need to maintain a distance of approximately 3.4 ft from the therapy patient.