Question

Which of the following is the expected result of a CT number CaLiBration test performed on a water phantom?

1) Increase in CT number
2) Decrease in CT number
3) No change in CT number
4) Cannot be determined without additional information

Answer 1

The expected result of a CT number calibration test on a water phantom is no change in CT number, as the scanner should be calibrated such that the CT number for water is set to zero, the reference standard.

Step-by-step explanation:

The expected result of a CT number calibration test performed on a water phantom is no change in CT number. A CT (Computed Tomography) calibration test is designed to ensure that the imaging system is producing accurate values representative of the scanned material. In the case of a water phantom, which is used to simulate human tissue, the CT number should be calibrated to zero, since water is the reference standard in Hounsfield units (the measurement scale for CT numbers).

The calibration test will confirm whether the CT scanner is properly calibrated. If it is well calibrated, there will be no change in the CT number. However, if the calibration is off, the test would identify a need for adjustment, but the expected and desired outcome of a successful calibration on a water phantom is no change.