Question | Answer |
Define radiology. | A branch of medicine concerned with the use of radiant energy or radioactive material in the diagnosis and treatment of disease. |
How are X-rays produced? | In an X-ray tube by focusing a beam of high-energy electrons onto a tungsten target. |
How does an X-ray produce an image? | Tissues of high density cause more X-ray beam attenuation and are shown as lighter grey or white on a radiograph. Less dense tissues and structures cause less attenuation of the X-ray beam and appear darker on radiographs. |
What colour does air appear on an X-ray? | Black. |
What colour does fat appear on an XR? | Very dark grey. |
What colour does soft tissue appear on an XR? | Grey. |
What colour does bone appear on an XR? | Very light grey. |
What colour does metal appear on an XR? | White. |
How many planes should you take an XR? | At least two. |
What is an AP view? | Anteroposterior. |
What is a PA view? | Posterior-Anterior |
Why is PA sometimes preferred? | It does not magnify the heart as much from behind, so gives a more accurate representation. |
What is a mammography? | A specific type of XR that uses a low does of XR system designed for creating detailed images of the breast. |
When is mammography used? | As a screening tool to detect early breast cancer in women without signs or symptoms of disease.
Or to diagnose a breast disease in women with symptoms such as a lump, pain or nipple discharge. |
What is fluoroscopy? | A type of medical imaging that shows a continuous XR image on a monitor. |
When is a fluoroscopy used? | When real time examination of the patient's body is required. E.g. orthopaedic implants during surgery, catheters and pacemakers. |
What is an angiography? | An XR technique used in the examination of the arteries, veins and organs to diagnose blockages. |
What occurs in an angiogram? | The radiologist inserts a thin tube, called a catheter, into an artery or vein from an access point (arm or groin).
A substance called a contrast agent is injected to make the blood vessels visible on the XR image. |
Define tomography. | A method that produces images of single tissue plane. |
What does CT and CAT stand for? | Computed tomography and Computerized axial tomography. |
What does a CT scan produce? | Cross-sectional images or "slices" of anatomy. |
What are the advantages of CAT scans? | Fast.
Readily available.
Good imaging of bony structures, abdomen and lungs. |
What are the disadvantages of CAT scans? | High radiation.
Not so good at imaging soft tissue such as brain and spinal cord. |
What is nuclear medicine also known as? | Scintigraphy. |
How does scintigraphy work? | Uses gamma radiation to form images following the injection of various radiopharmaceuticals. |
What is the most common radionuclide? | Technetium. |
What does metastable mean? | Means that the technetium atom has two basic energy states: high and low. |
What happens as the technetium transforms energy states? | As the technetium transforms from the high-energy state to the low-energy state, it emits a quantum energy in the form of a gamma ray. |
What happens when the gamma ray is emitted? | Gamma rays emitted by the radionuclides are detected by a gamma camera that converts that absorbed energy of the radiation to an electrical signal.
The signal is analysed by a computer and displayed as an image. |
What are the main advantages of scintigraphy? | High sensitivity and providing functional information as well as anatomical information. |
What does SPECT stand for? | Single photon emission CT. |
What is SPECT? | A scintigraphic technique whereby the computer is programmed to analyse data coming from a single depth within the patient. |
Why is SPECT good? | It allows greater sensitivity in the detection of subtle lesions overlain by other active structures. |
Why would you combine SPECT with CT? | Fuses highly sensitive SPECT findings with anatomically accurate CT images, thus improving sensitivity and specificity. |
What does PET stand for? | Positron emission tomography. |
What is PET? | A combination of computed tomography and scintillation scanning most commonly used in oncology. |
What are the advantages of scintigraphy? | Good functional information.
Good localization of pathology. |
What are the disadvantages of scintigraphy? | High radiation dose.
Not so good at differentiating between different pathologies. |
What MRI stand for? | Magnetic Resonance Imaging. |
What is the principle of MRI? | Uses a powerful magnetic field and radio frequency pulses to produce detailed images of the body's internal structures as cross-sectional images or slices. |
How does MRI work? | |