Computed tomography [CT Imaging]
Computed tomography [CT Imaging]
Computed tomography (CT) [also known as computed axial tomography (CAT)] scanning involves x-rays. As the x-rays pass through the body, they are absorbed by tissue so that an overall “mean attenuation” image results along the ray path. Spatial resolution is not determined by wavelength but by focal spot size of the x-ray tube and scatter from tissue; the state of the art is about 1 mm. Radioactive contrast agents can be ingested or injected to improve visualization of vessels. Though exposures are short, x-rays are a form of ionizing radiation, so that dosage effects can be cumulative and extra precautions are needed for sensitive organs such as eyes and for pregnancies.
CT equipment is large and stationary so that a person can fit inside, and as a result, it is relatively expensive to operate. Consecutive pictures of a moving heart are now achievable through synchronization to ECG signals. The resolution of CT images is typically 1 mm. CT scanning creates superb images of the brain, bone, lungs, and soft tissue, making it complementary to ultrasound.
Although the taking of CT images requires training, it is not difficult. Interpretation of CT cross sectional images demands considerable experience for definitive diagnosis.
Related pages:
- Medical Imaging
- Electrocardiogram [ECG]
- Electroencephalogram [EEG]
- How does ultrasound work?
- Ultrasound
- Magnetic resonance imaging [MRI]
- Positron emission tomography [PET]
- Commonly Used Radionuclides in Nuclear Medicine
