CT scanner

What is CT?

During a CT scan, x-rays are continuously emitted while rotating 360 degrees around the body. Different structures make up different densities within the body and as the x-rays travel along their path their energy and intensity will be altered depending on which densities they hit. The detectors sitting at 180 degrees to the x-ray emission source (and also rotating) will be able to collect this numerical data and from this the sophisticated computer software can calculate which structures the x-rays have passed though and their location in the body generating a grey scale . Dense areas (such as bone) are whiter on the images while less dense areas (like air) appear darker.

Data sets can be processed to best demonstrate different anatomy, primarily soft tissue, bone and lung and these can be retrospectively reconstructed in many planes. Iodinated contrast may be injected intravenously to gather further information for certain conditions and may also be injected intrathecally and intra-articularly in specialised circumstances. For the majority of our orthopaedic patients a contrast injection is not required as we are able to acquire all our diagnostic material without it.

When is CT used?

Common indications for CT are coronoid elbow disease, antebrachial growth deformity, patellar luxation, oncology staging, further assessment of hip dysplasia, cranial cruciate disease and complex fractures, surgical planning, trauma and post-operative implant assessment. CT scans are a relatively short examination and may be performed under sedation or general anaesthetic.