DHA Radiology / Radiographer study guide
DHA Radiology / Radiographer · Work through your exam, one topic at a time.
The Dubai Health Authority (DHA) radiographer licensing examination is the professional assessment that diagnostic radiographers must satisfy in order to be registered to practise in the Emirate of Dubai. It is intended for radiographers who hold a recognised qualification in diagnostic radiography or medical imaging and who now need to show that their knowledge and judgement meet the standard expected of a practising professional within the UAE healthcare system. The DHA Radiology / Radiographer study guide has 8 sections and about 3,750 words.
01Radiation Protection
Every exposure must satisfy three ICRP principles: justification (the benefit outweighs the risk), optimisation (ALARA, taking economic and social factors into account), and dose limitation (which applies to occupational and public exposure, never to the patient's own medical exposure). Limits are constraints, not targets: occupational effective dose 20 mSv per year averaged over five defined years (100 mSv in that period, with no single year above 50 mSv); lens of the eye 20 mSv per year averaged; extremities and skin 500 mSv per year; public 1 mSv per year.
337 words, about 2 min02Dosimetry and Radiation Biology
Absorbed dose (gray, joules per kilogram) describes energy deposited in tissue. Equivalent dose (sievert) applies the radiation weighting factor, which is 1 for x-rays and gamma rays.
299 words, about 1 min03Radiographic Physics
Electrons are emitted thermionically from a tungsten filament, accelerated by the tube potential, and strike the focal spot, where about 99% of energy becomes heat. Bremsstrahlung produces the continuous spectrum; characteristic radiation appears only when tube potential exceeds the K-shell binding energy of the target (about 70 keV for tungsten, giving emissions near 59 and 67 keV).
296 words, about 1 min04Equipment and Imaging Informatics
Computed radiography uses a photostimulable phosphor plate. Direct digital radiography uses indirect conversion (caesium iodide scintillator with an amorphous silicon photodiode array) or direct conversion (amorphous selenium photoconductor).
278 words, about 1 min05Radiographic Positioning and Procedural Technique
Describe projections, not views. Know AP, PA, lateral (state the side nearest the image receptor), oblique, axial and tangential.
286 words, about 1 min06Image Quality
Spatial resolution is the ability to resolve small high-contrast detail, measured in line pairs per millimetre or by MTF. Contrast resolution is the ability to distinguish low-contrast structures and is limited by noise.
287 words, about 1 min07Image Evaluation and Quality Assurance
Assess against explicit criteria: correct patient and marker, all required anatomy included, no rotation, adequate inspiration or positioning, exposure index within range, acceptable contrast and sharpness, no artefact, and no avoidable collimation of essential anatomy. Reject analysis should classify cause - patient, equipment, technique or processing - and feed a cycle of improvement rather than blame.
278 words, about 1 min08Cross-Sectional Anatomy
Axial (transverse), coronal, sagittal, oblique and curved reformats. Axial CT and MRI images are conventionally displayed as if viewed from the patient's feet, so the patient's left appears on the viewer's right.
1,689 words, about 8 min