Exam 1 Introduction to radiology Flashcards
Explain X-rays
Radiation passes through patient strikes cassette to create an image, rays don’t pass through dense tissues as easily creating the outlines
What is Computed Radiography?
x-ray passes through patient strikes a sensitized plate which is read and digitized into a computer image
What is digital radiography?
x-ray strikes a plate of sensors producing the computer image directly
Which type of radiography sends the image directly to the computer: digital or computed?
digital
Why are x-rays harmful to biological organisms?
can displace electrons from energy level, creating a free radical
What are the different risks of radiation?
deterministic effects resulting in cell death: skin erythema, epilation, radiation burns or cataracts; stochastic effects: cancer/leukemia
T/F: pediatric patients are at increased risk for stochastic effects
True; higher proportion of rapidly dividing cells
What are examples of background radiation exposure?
radon, radioactivity from rocks, cosmic rays
What accounts for 95% of all radiation exposure?
medical imaging
What does the risk model look like that estimates lifetime risk of radiation induced cancer?
linear no-threshold dose response curve (dose and risk are directly proportional
What questions should you ask to reduce the risk of radiation-induced cancer?
Is this test necessary? Will it change the management of the pt? Is there a better study that would answer the question?
What are the technical factors that can be controlled to reduce the exposure to radiation?
decrease tube current/tube voltage, wider collimation or change speed table moves, automated methods
What trimester is absolutely critical to avoid radiation exposure?
First trimester (organ exposure); after 2 gestational weeks it gets better
What is the first line of study to look at lungs, heart and skeleton?
Plain films
What are the main uses for plain films/x rays
CXR, spine films, skeletal films, abdoment films
What should always be done when getting an x-ray
get more than 1 view to put it in more of a 3D
What is basis of ultrasound?
high frequency sound waves reflect back based on distance/density
Does ultrasound use ionizing radiation?
negatory
What is the primary way of evaluation pregnancy?
ultrasound
What are the best uses of ultrasound?
pregnancy, gallbladder, abdominal/pelvic pain in women and children
T/F: ultrasound is good for evaluating veins for DVT?
False
Do CT scans use IR?
yes; a lot
How does CT work?
gantry moves around patient taking x-rays at many angles and computer puts them all together
What is CT best used for?
acute hemorrhage of brain, mass effect or herniation of brain, chest imaging, PE, tumor, interstitial lung disease, abdominal screening (tumor, inflammation, obstruction), UTI and kidney stones