Introduction to Imaging Flashcards
Define what an x-ray is.
An X-ray is a type of high-energy electromagnetic radiation used in medical imaging to view the inside of the body. It passes through tissues, with dense areas like bones absorbing more X-rays and appearing white on the image, while softer tissues appear darker. The resulting image, called a radiograph, helps diagnose conditions such as fractures, infections, or tumors.
Recall in general terms the principles of xray generation and image capture.
X-rays are generated in an X-ray tube, where electrons are accelerated towards an anode, producing X-rays through Bremsstrahlung and characteristic radiation. The X-ray beam passes through the body, with different tissues absorbing varying amounts. The remaining X-rays are captured by a film or digital sensor, creating an image. Dense tissues like bones appear white, while softer tissues appear darker, resulting in a radiograph that helps diagnose medical conditions.
Explain why different anatomical structures have different appearances on x-ray imaging.
Different anatomical structures have different appearances on X-ray imaging due to the varying densities and compositions of tissues, which affect how much X-ray radiation they absorb.
Bone: Bone is dense and contains a high amount of calcium, which absorbs a large amount of X-rays. As a result, bones appear white or light gray on X-ray images because they block most of the X-ray beam from passing through.
Soft Tissues: Soft tissues like muscles, fat, and organs are less dense than bone and absorb fewer X-rays. These tissues allow more X-rays to pass through, so they appear darker on the X-ray image.
Air-filled Structures: Structures filled with air, like the lungs, absorb very few X-rays and appear very dark or black on X-rays, since they allow most of the X-ray beam to pass through.
Fat: Fat is less dense than muscle or bone and absorbs fewer X-rays, so it appears as a darker gray compared to muscle but lighter than air-filled structures.
In summary, the denser the tissue, the whiter it appears on the X-ray image (such as bone), and the less dense the tissue, the darker it appears (such as air-filled lungs or fat). This contrast allows for differentiation of various anatomical structures.
Recall the basic principles of CT, ultrasound and fluoroscopy and explain their strengths and weaknesses in simple, general terms.
CT provides detailed images and is great for complex diagnoses but involves radiation.
Ultrasound is safe, portable, and effective for soft tissues but is limited by image quality and depth penetration.
Fluoroscopy offers real-time imaging for dynamic functions but also involves radiation and has lower image resolution compared to other modalities.
Describe the scientific basis of the use of iodinated contrast media.
Iodinated contrast media enhance the visibility of internal structures in X-ray and CT imaging by exploiting iodine’s ability to absorb X-rays due to its high atomic number. This contrast allows for better differentiation between tissues, aiding in the diagnosis of conditions like vascular abnormalities, tumors, and other diseases.
Describe the scientific basis of the hazards of ionising radiation.
The hazards of ionizing radiation stem from its ability to ionize atoms, causing DNA damage, mutations, and cell death, which can lead to cancer and other health problems. The biological effects depend on the radiation dose, type, and the tissue being irradiated. High doses can cause immediate tissue damage and acute radiation sickness, while low doses, accumulated over time, increase the risk of long-term effects like cancer. Radiation protection strategies aim to minimize exposure to reduce these risks.
Be able to explain the strengths and weaknesses of common radiological modalities and tests in simple, general terms.
X-ray:
Strengths: Quick, accessible, good for bone imaging, and low cost.
Weaknesses: Limited soft tissue detail, involves radiation, and only provides 2D images.
CT (Computed Tomography):
Strengths: Detailed 3D images, good for bones and soft tissues, fast.
Weaknesses: High radiation exposure, expensive, less effective for soft tissues compared to MRI.
MRI (Magnetic Resonance Imaging):
Strengths: No radiation, excellent for soft tissues, detailed images.
Weaknesses: Expensive, time-consuming, can cause discomfort for some patients, and not ideal for bone imaging.
Ultrasound:
Strengths: Safe, no radiation, real-time imaging, portable, and low cost.
Weaknesses: Limited depth, lower resolution, and operator-dependent.
Fluoroscopy:
Strengths: Real-time imaging, useful for guiding procedures.
Weaknesses: Involves radiation, lower resolution, and limited soft tissue imaging.
Nuclear Medicine (e.g., PET, SPECT):
Strengths: Provides functional information, detects disease early.
Weaknesses: Radiation exposure, lower resolution, and high cost.
