1.1: Instrument Parts1. VivaCT 40 – The main CT scanner unit.
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From Figure 1:
2. If a scan needs to be printed, it will be printed from this.
3. Computer Interface – This is where the scan is set up and then executed. After a scan is completed, reconstruction and viewing will be done here.
From Figure 2:
4. This light indicates power to the scanner.
5. Emergency Off (EMO) – Press only in case of emergency. If the system needs to be reset, make sure this is pulled out.
6. When a scan is in progress, this light will be on. During that time DO NOT open the scanner door or the scan will be aborted.
7. Scanner Door – This is where the sample entrance is covered. Opening this during an acquisition will cancel the scan.
From Figure 3:
8. Sample entrance – This is where the sample bed will be placed.
9. Sample tube – This is where your sample will be placed most of the time. There are multiple sizes of tubes.
10. Sample bed – The sample is placed in a tube located at the front portion of the sample bed, or for large samples, in the bed with the area of interest protruding out.
1.2: Getting started
The system should be powered ON all the time. If you come in and the ‘In Progress’ light is on, DO NOT open the scanner door. If a scan is running and you open the door, it will abort the scan. Scans can take up to several hours, so if one is in progress, please reschedule for a later time.
There is a login for the computer and unless there is a problem with the scanner, it will always be logged in. If it is logged out, that is probably due a malfunction. Usually a note will be placed to indicate this.
The first time you use the system, you will have to fill out the 'New Operator form' (Figure 4). The only field that is mandatory is the 'Name' field. For all subsequent logins, just enter the first few letters of your name and press Return (Figure 5).
Note about operating system for vivaCT:
• On the top right corner there is a minimize/maximize button
• On the top left corner there is the menu bar.
1.3: Preparing your sample
Objects being scanned should be smaller than 35 mm. The largest area that can be scanned is 38 mm. If the size is close to this, then you are likely to lose part of your image.
Most samples will be small enough to fit one of the tubes (sample tube shown in Figure 6). Beam hardening is when the X-rays get scattered by the very dense metal and cause distortions in the final image. To prevent beam hardening, place sample at a distance from the metal tip at the bottom of the holder. To achieve this, use a piece of foam or Styrofoam to create space.
Place something on top of your sample to prevent movement. While the sample will not actually move, the scanner itself creates vibrations such that if the sample is not immobilized, then artifacts (distortions) can occur in your final image. A good test of immobility is tapping the tube with your finger. If nothing moves, it should not move during the scan. If your sample contains some liquid that could leak out into the machine, it is very important to cap the end with paraffin wax.
It is very simple to position the sample into the scanner. After your sample is prepared in the tube, place it into the slot of the sample bed. The sample bed will now slide easily into the track on the scanner. Be sure to lift the pin on top to slide it in (Figure 7).
Once the bed is in the desired position, pull back on the bed and place the lever tightly as seen in Figure 8. After the sample is secure, close the scanner door. Your sample is now ready to be scanned.