CT Safety: CTDI and DLP - Video Lesson

Welcome back. This lesson is about dose measurements in CT. In CT, it's a little tricky to measure the patient dose directly. So instead, we use these two calculations. The CTDI and the DLP. Let's start by talking about the CTDI. CTDI is actually an that stands for computed tomography dose index. The CTDI is not a true measurement of the patient dose. It really is an index of the dose. So here's how it works. Medical physicist scans two CTDI phantoms embedded with ionization chambers to measure the absorbed dose the phantom. You see an example of one of these in the image to the right. The first phantom is a sixteen centimeter diameter phantom, and it represents the patient's head. The second phantom measures thirty two centimeters in diameter, and it represents a patient's body. The physicist this is going to scan these phantoms numerous times using all kinds of scan parameters. In fact, the same kinds of scan parameters that we would use during actual patient scanning, the