CT scanning delivers higher radiation doses than conventional X-ray — a single chest CT delivers approximately 100 times the effective dose of a chest X-ray. In a busy UAE radiology department performing hundreds of CT scans per week, the cumulative radiation burden on the patient population is significant. Regulatory bodies worldwide — and FANR in the UAE — require CT operators to optimise their scan protocols to deliver the minimum dose consistent with diagnostic quality. This is the ALARA principle (As Low As Reasonably Achievable) applied to CT. This article explains the key dose optimisation strategies available to UAE CT departments.
The biological effects of ionising radiation are probabilistic — higher doses increase the probability of radiation-induced cancer, but do not guarantee it. For an individual patient, the risk from a single CT scan is small. For a population of millions of patients undergoing CT scans annually, the statistical contribution to cancer burden is not negligible.
From a regulatory perspective, FANR and DOH require all UAE CT departments to: • Establish local diagnostic reference levels (DRLs) based on their scan protocols • Compare their DRLs against national and international reference values • Investigate and optimise if their DRLs exceed reference values • Document their dose optimisation efforts as part of the quality assurance programme
Modern CT scanners are equipped with automatic exposure control (AEC) systems — also known as automatic tube current modulation (ATCM). These systems continuously adjust the tube current (mA) during the scan to maintain consistent image quality as the beam passes through regions of different thickness and density. Without AEC, a single tube current is applied throughout the scan — acceptable for the thinnest part of the body it passes through, but unnecessarily high for the thicker parts.
AEC systems can reduce CT dose by 20–40% compared to fixed-mA protocols without any reduction in diagnostic image quality. Every UAE CT department should have AEC enabled on all scanner types that support it. RevirzaMed's medical physicists verify AEC function and optimisation as part of CT QC assessments.
The most common source of unnecessary CT radiation dose is using a protocol designed for a demanding diagnostic task when a simpler, lower-dose protocol would suffice. Examples:
• Using a routine abdomen protocol for a follow-up scan of a known benign cyst — a much lower-dose protocol is appropriate • Performing a triple-phase CT (three full acquisitions) when a single-phase scan addresses the clinical question • Using adult scan parameters for a child — paediatric patients require significantly lower scan parameters
RevirzaMed's medical physicists review CT protocols for all scanner types and clinical indications, and recommend optimised parameters that achieve diagnostic quality at reduced dose.
The tube voltage (kVp) is the second most important dose parameter after mA. Lower kVp settings produce lower-energy X-ray beams that deliver less radiation dose for the same image noise level in many patients.
For contrast-enhanced CT, lower kVp settings (80–100 kVp versus the traditional 120 kVp) produce higher contrast enhancement from iodinated contrast media, often allowing the iodine dose to be reduced while maintaining diagnostic quality. For standard-sized or smaller patients, 100 kVp or even 80 kVp protocols deliver significantly lower dose than 120 kVp protocols.
Traditional CT image reconstruction uses filtered back-projection (FBP), which is fast but generates significant image noise at lower dose levels. Modern CT scanners offer iterative reconstruction (IR) algorithms — statistical methods that progressively reduce image noise through multiple reconstruction passes. IR allows diagnostic quality images to be produced from raw data collected at 20–50% lower dose than FBP requires.
All major CT scanner manufacturers now offer IR — marketed under various names (ASIR, iDose, ADMIRE, AIDR, etc.). UAE CT departments should have IR enabled and optimised for their protocols. RevirzaMed verifies IR implementation as part of CT QC assessments.
Knowing whether your CT dose levels are appropriate requires benchmarking against national and international diagnostic reference levels (DRLs). RevirzaMed performs CT dose audits for UAE facilities — measuring CTDI and DLP for standard scan types, comparing them against IAEA and European DRL values, and providing recommendations for optimisation where needed. These audits produce a report suitable for submission to FANR, DOH or DHA as evidence of active dose management.
DRLs are doses that should not be routinely exceeded for a given standard examination in an average-sized patient. They are not dose limits — exceeding a DRL does not mean a patient was harmed. They are management tools that identify departments whose doses are above the achievable level and prompt investigation and optimisation.
FANR's radiation protection regulations require healthcare facilities to apply the ALARA principle — keeping doses as low as reasonably achievable. For CT, this requires facilities to have optimised protocols and to have a documented dose management programme. RevirzaMed's CT dose audit service provides all the documentation required.
RevirzaMed Healthcare Solutions — Abu Dhabi's trusted FANR Approval and medical equipment specialists since 2015.