Question

question 8 / 40
which of the following would double the quantity of photons in the x - ray beam? (select two)
double the time and double the milliamperage (ma) simultaneously
double the exposure time, but do not change the milliamperage (ma)
double the exposure time and cut the milliamperage (ma) in half
double the milliamperage (ma), but do not change the exposure time

Explanation:

Step1: Recall photon - quantity relationship

The quantity of photons in an x - ray beam is proportional to the product of milliamperage ($mA$) and exposure time ($t$), i.e., $Photon\ quantity\propto mA\times t$.

Step2: Analyze each option

• Option 1: If we double the time ($t$) and double the milliamperage ($mA$) simultaneously, the new product is $(2mA)\times(2t)=4(mA\times t)$, which quadruples the photon quantity.
• Option 2: If we double the exposure time ($t$) and keep $mA$ the same, the new product is $mA\times(2t) = 2(mA\times t)$, which doubles the photon quantity.
• Option 3: If we double the exposure time ($t$) and cut the milliamperage ($mA$) in half, the new product is $(\frac{1}{2}mA)\times(2t)=mA\times t$, which keeps the photon quantity the same.
• Option 4: If we double the milliamperage ($mA$) and keep the exposure time ($t$) the same, the new product is $(2mA)\times t=2(mA\times t)$, which doubles the photon quantity.

Answer:

• Double the exposure time, but do not change the milliamperage (mA)
• Double the milliamperage (mA), but do not change the exposure time