For a SPECT study requiring 2 million counts and a count rate of 65,000 cpm over 64 steps, how long should each step last?

For a SPECT study requiring 2 million counts and a count rate of 65,000 cpm over 64 steps, how long should each step last?

• A. 21 seconds
• B. 29 seconds
• C. 31 seconds
• D. 48 seconds

Answer: (B)

To determine how long each step should last in a SPECT study requiring a total of 2 million counts, we first need to calculate the total acquisition time based on the desired count rate and then distribute that time evenly across the specified number of steps. Given a count rate of 65,000 counts per minute (cpm), we can first convert that to counts per second (cps) for clarity: \[ 65,000 \text{ cpm} \div 60 \text{ seconds} = 1,083.33 \text{ cps} \] Next, we calculate the total acquisition time needed to reach 2 million counts: \[ \text{Total counts} \div \text{Count rate} = 2,000,000 \text{ counts} \div 1,083.33 \text{ cps} \approx 1,846.15 \text{ seconds} \] Now that we have the total time, we divide this by the number of steps, which in this case is 64: \[ \text{Time per step} = \text{Total time} \div \text{Number of steps} = 1,846.15 \text{

To determine how long each step should last in a SPECT study requiring a total of 2 million counts, we first need to calculate the total acquisition time based on the desired count rate and then distribute that time evenly across the specified number of steps.

Given a count rate of 65,000 counts per minute (cpm), we can first convert that to counts per second (cps) for clarity:

[

65,000 \text{ cpm} \div 60 \text{ seconds} = 1,083.33 \text{ cps}

]

Next, we calculate the total acquisition time needed to reach 2 million counts:

[

\text{Total counts} \div \text{Count rate} = 2,000,000 \text{ counts} \div 1,083.33 \text{ cps} \approx 1,846.15 \text{ seconds}

]

Now that we have the total time, we divide this by the number of steps, which in this case is 64:

[

\text{Time per step} = \text{Total time} \div \text{Number of steps} = 1,846.15 \text{