Introduction to Radiology Flashcards
Summarize Roentgen’s experiment
Worked with CATHODE ray tube. He evacuated the tube of all air, filled it with a special gas, and passed a high electric voltage through it. shielded the tube with heavy black paper. he had produced a previously unknown “invisible light,” or ray capable of passing through the heavy paper. X-ray would pass through the tissue of humans leaving the bones and metals visible
X-rays were discovered by William Roentgen while experimenting with a cathode radiation.
Computed Radiography (CR) -Digital Radiography (DR)
the x-rays that pass through the patient strike a sensitized plate which is then read and digitized into a computer image
-the x-rays strike a plate of sensors producing the computer image directly
-where digital X-ray sensors are used instead of traditional photographic film.
How can X-rays that are short wave length, high energy rays, harm biological tissue?
it can displace electrons from its energy level or shell around the nucleus
CAN FORM FREE RADICALS
Ionizing Radiation is increasing, what test is responsible for the majority of the total exposure?
CT’s responsible for most exposure
What are two common effects related to high exposure to radiation?
Deterministic effects: result from cell death (burns, cataracts) predictable
Stochastic Effects: Cancer or Leukemia, unpredictable due to effects being delayed
Who is at greater risk for Stochastic effects?
Pediatric Patients due to Higher proportion of rapidly dividing and therefore radiosensitive cells. Can see cancer later in life
what is the scientific unit of measurement?
(effective dose) is measured in millisieverts (mSv), varies in different parts of the body
what is the standard exposure per year in the US?
3mSv per year
what doses categories increase risk for cancer?
FOLOWING RELATIVELY LOW-DOSE EXPOSURES (5-125mSv)
what are the top effective doses of CT chest, renal, head and extremity?
Head or Facial Bones: 2 mSv C-spine or neck: 2 mSv Chest or PE: 8 mSv Abdomen: 7.5 mSv Pelvis: 7.5 mSv Renal or A/P: 15 mSv Extremity: 0.5 mSv
Besides using X-ray or CT what are two test that do not use ionizing radiation?
Ultrasound and MRI
What are ways to decrease radiation dose?
decrease the tube current or the tube voltage
wider collimation or change the speed that the table moves
….these compromise quality
When do you avoid radiation exposure in prego women?
First trimester ( time of organ formation) is felt to be particularly critical and we try to avoid exposure
Risk decreases with age, so prefer third trimester scanning
diagnosis of mom is priority to baby… judge carefully
What test is first line study for evaluation of lungs, heart and skeleton due to availability, speed and low cost?
X-rays or Plain films
X-rays are absorbed by _____or _____. what is the color?
metals or bone
radiopaque and look white
