Intro to imaging Flashcards
What is the difference between ionising and non-ionising radiation?
Ionising radiation removes electrons from atoms and includes X-rays, gamma rays, and some UV. Non-ionising radiation includes sound waves in ultrasound and radio waves in MRI.
What are the strengths of radiography?
Radiography provides great spatial resolution, especially for bone imaging. It is also cheap and widely available.
What are the weaknesses of radiography?
Radiography is limited to 2D images, making it challenging to visualize structures behind the heart. It also relies on ionising radiation and has limited soft tissue visualisation.
How does X-ray production and interaction with the patient occur?
X-ray production involves generating a beam of X-ray photons. When the X-ray beam interacts with the patient, most photons are absorbed by filtration due to their low energy. The remaining photons can be absorbed, transmitted through the patient, or scattered from their original path.
What are the four tissue densities typically seen on a chest X-ray?
The four tissue densities seen on a chest X-ray are air, fat, soft tissue/fluid, and bone.
What is fluoroscopy?
Fluoroscopy is a real-time examination technique that involves the continuous production of X-rays. It is used for various procedures such as barium examinations, angiography, cardiac procedures (e.g., stents), urology procedures, and in-theatre imaging using a C-arm.
What are the strengths of computed tomography (CT)?
CT provides cross-sectional imaging, allowing detailed visualization of anatomical structures. It also offers high spatial resolution and is widely available.
What are the weaknesses of computed tomography (CT)?
CT uses ionizing radiation, which can be a concern for repeated or high-dose imaging. Additionally, CT has limited soft tissue contrast compared to other imaging modalities.
What are the strengths of ultrasound imaging?
Ultrasound imaging uses non-ionising radiation, making it safe for repeated use. It provides multiplanar imaging, allowing visualization of structures from different angles. Ultrasound is also dynamic, meaning it can capture real-time movement. Additionally, Doppler ultrasound can assess blood flow within the body.
What are the weaknesses of ultrasound imaging?
Ultrasound imaging is operator-dependent, meaning the quality of the images can vary based on the skill and experience of the operator. Ultrasound cannot penetrate through bone or gas, limiting its ability to visualize structures in those areas.
What are contrast agents used for in medical imaging?
Contrast agents are used in most imaging modalities to improve the visualization of organs, blood vessels, and pathology. They help enhance the contrast and delineation of structures within the body.
How are contrast agents administered?
Contrast agents can be administered through various routes, including injection, swallowing, or rectal administration, depending on the imaging procedure and the area being examined.
What are iodinated contrast media?
Iodinated contrast media are pharmacological agents that are bound to iodine. They are radio-opaque and consist of non-ionic water-soluble compounds.
In which imaging procedures are iodinated contrast media used?
Iodinated contrast media are used in CT scanning and angiography/interventional procedures to improve the visualization of blood vessels, organs, and abnormal pathology.
What are the risks associated with contrast agents?
Risks include allergic reactions, so patient history should be assessed before administration. Contrast agents should be avoided if possible during pregnancy, as they can cross the placenta.
