CT Lab

Today we had our lab for our course Radiation Detectors and Imaging Systems. It's quite fun cos we got to do a full CT (Computer Tomography) scan on poor Barbie. Basically, for the sake of scientific pursuit, Barbie was inserted with a metal ball bearing somewhere in her torso. We were supposed to locate the location of the "patient's tumour" using the CT scan. This time, I was very diligent in taking notes, so that I'd know what to write for the report.. Sigh.. It's very slack though.. U're supposed to hand in the report 2 weeks after lab, when the report is kind of short anyway.

Okay, so you have a source, Am-241, at one side emitting photons. We select one low and one high energy range of the photons to observe. At the other end, you have a detector that will allow you to know how much photons are absorbed or passed through. The metal ball-bearing would absorb more photons and lead to a lower amt of photons being detected at the end. It's pretty automated, the machine simlpy rotates every 6 degrees for 180 degrees at each position along her torso, and then repeats it another 5mm down her torso. First we conduct CT slicing to approximate the positiona and then conduct a full CT scan. Then once the machine is in working, we go for a 45 minutes coffee break.. Unbelievable...
Patient Barbie undergoing CT scan.

When we are back, the machine has been kind enough to give us the following results.


Tumour found near Barbie's left back. Blue area due to higher absorption of photons. In this case, the result is more apparent using the higher energy photons.