Test c-arm imaging for problems using an x-ray phantom, a highly specialized object utilized in medical imaging for quality control, calibration, and education
There are two main types of phantoms, anthropomorphic and calibration. The name is used interchangeably for each object despite their differences.
Anthropomorphic phantoms are objects that simulate patients, made of materials with similar tissue characteristics to normal biological organisms. They can be used for trial and error to assess the optimal use of radiation such as new protocols or image reconstruction techniques.
Anthropomorphic phantoms can be utilized for teaching staff different imaging techniques or exposure factors.
A calibration phantom is often a cylinder, or plate with densities of already known values. They are utilized in quality control to ensure images are reconstructing the imaged phantom to the correct density values. Deviation from these values can indicate a need for imaging equipment service.
If you don’t have a phantom, use radiopaque objects on the procedure table such as keys, coins, sheets, towels etc. Position the C-Arm over the procedure table.
- Images dark, grainy or light?
- Edges sharp or blurry?
- Does the C-Arm render the objects with good tonal value?
- Good range of blacks, whites, and grays?
If not, try to adjust the contrast or brightness using the controls, or the edge enhancement feature.
On older C-Arms, the image intensifier or the x-ray tube may need to be replaced or recalibrated, however sometimes a simple height adjustment of the C-arm can improve the image quality.
Make sure the body part is centered to the tube. If the anatomy is below or above the iso-center of the image intensifier, the differences in densities between the air and the body part can throw off the automatic exposure controls which produces a C-Arm problem with high contrast or a grainy images.
If a C-Arm positioned near different tissue densities such as the thoracic spine and the lumbar spine, both densities will try to adjust at the same time. This can cause a grainy or a high contrast image.
Center the tube to the densest area first, wait for the automatic exposure to adjust then move to the body part being imaged.
Different densities can cause a blooming effect around the edge of the screen, especially if the patient has a metallic device such as a prosthetic hip.
Extend the Lifetime of Your C-Arm:
- Get annual preventative maintenance.
- Always be sure to plug in the C-Arm when not in use. Your batteries will last longer if kept charged.
- Regular cleaning.
- C-Arm covers.
- Clean the tube.
- Image intensifier.
- Power cables.
- Check and clean fan filters.
- Use protective C-Arm drapes during your procedures.
- Protect monitors by adjusting the sleep mode setting. A shorter sleep mode time is better for units that have CRT monitors.