Calculating Effective Dose for CT Scanners Using mA Modulation
Research type
Research Study
Full title
Methods of Calculating Effective Dose for Computed Tomography Scanners Operating Tube Current Modulation
IRAS ID
207168
Contact name
Jonathan Dixon
Contact email
Sponsor organisation
Newcastle upon Tyne Hospitals NHS Foundation Trust
Duration of Study in the UK
1 years, 0 months, 1 days
Research summary
Computed tomography (CT) scans are performed routinely in hospitals to aid the diagnosis of patient conditions.
Traditionally, scanners would use the same exposure factors (and so the same amount of radiation) for all patients for any particular examination, irrespective of the individual patient’s size or weight. This is less than ideal, as smaller patients do not need as much radiation to create their images compared to large patients. Modern CT scanners, however, are able to adjust the amount of radiation being used during the scan to optimise for inherent differences in individual patient size, and for changes in size across an individual patient (for example, neck versus abdomen).
While being a useful diagnostic tool, the radiation (x-rays) that CT scaners use to acquire images can be harmful as it has the potential to induce cancer at some point in the future. In order to estimate the associated future cancer risk it is important to understand exactly how much radiation has been delivered together with its distribution within to the patient.
A quantity called effective dose is used to quantify the overall risk to the patient and this is calculated using specific information provided by the CT scanner. Common methods of calculation assume a constant amount of radiation throughout the scan as would have been the case with traditional scanners. However, with modern scanners that are able to vary the amount of radiation, this assumption is no longer true.
This project will involve analysing archived patient scans to retrieve the additional information required to more accurately calculate effective dose by accounting for the varying amount of radiation used for the individual patient’s examination. The effective dose will then be calculated and compared to that calculated using the existing method that assumes a fixed amount of radiation over the entire scan.REC name
Wales REC 4
REC reference
16/WA/0228
Date of REC Opinion
5 Aug 2016
REC opinion
Favourable Opinion