Computed Tomography (CT) Scan

CT is a specialised form of investigation used to investigate bone injuries when x-ray results are inconclusive. (RCR IRefer, 2017) CT is an imaging technique that uses computer technology with x-ray equipment to cross-sectionally image the body.

It is a recommended form of imaging during specialised imaging. The guidelines state ‘CT is helpful to evaluate complex bony injuries or when XR is inconclusive’.

How Does CT Work?

• The X-ray tube is linked to a detector.

• Both the X-ray tube and detector will then circle you.

• They take hundreds of x-ray pictures which the computer then combines into a ‘slice’.

• This process is then repeated until a full image of a cross-section of the desired body part is complete.

Advantages:

· Allows for visualisation of internal organs.

· Avoids superimposition of tissues.

· CT allows things to be viewed on different planes.

· Modern day CT scanners are able to scan your entire body in less than 30 seconds.

Disadvantages:

· Uses a higher dose of radiation than an x-ray and therefore exposes you to more radiation.

· The gantry in the CT scanner has a set circumference and therefore, some patients are unable to have a CT scan due to their size.

CT Procedure:

· A CT is a non-invasive exam but you must remove all jewellery, watches etc... to avoid any artefacts showing up on the scan. These types of objects may obstruct the area being examined on the scan.

· You are then asked to lie on the bed in a supine (on your back) position with arms placed over your head for body scans or down by your side for brain scans etc.

· The table then moves in and out of the gantry. 

· If necessary an intravenous contrast (IV) may be injected or an oral contrast administered to help show the region of interest more clearly on the scan. It is used when tissues or organs of the same density are close together or in front of each other.

CT Scan of shoulder:

The most common reason for a CT scan to be carried out on a shoulder is to evaluate whether it is a one time injury or a recurring one . The CT allows your doctor to identify any problems with the shoulder joint. For example: pain, stiffness or clicking noise.

As with an x-ray, you are exposed to radiation. Depending on the type of X-ray, the radiation dose will vary. However, the doctors will try to make it minimal.

A CT scan can also be used to show tears in the muscles, tendons, ligaments, and also to show inflammation of the joint.

References:

• Hosseinzadeh, S., Deangelis, J.P., Komarraju, A., Wu, A.C., et al. (2020) Imaging of Acute Shoulder Trauma. Seminars in Roentgenology. [Online]. Available from: doi:10.1053/j.ro.2020.07.018.

• iRefer Guidelines https://www.irefer.org.uk/guidelines [Accessed 10 November 2020]

• Krans, B., 2018. Shoulder CT Scan. [online] Healthline. Available at: https://www.healthline.com/health/shoulder-ct-scan#preparation [Accessed 14 October 2020].

• Linnau, K.F. & Blackmore, C.C. (2002) Bony injuries of the shoulder. Current Problems in Diagnostic Radiology. [Online]. 31 (2) pp.29–47. Available from: doi:10.1067/mdr.2002.122854.

• Two-views.com. 2020. What Is A Shoulder CT Scan? | Two Views. [online] Available at: https://two-views.com/ct/shoulder-scan.html [Accessed 14 October 2020]