Diagnostic Imaging Flashcards
Wavelength and frequency are __ proportional
Inversely
List 3 properties of x-rays
- Short wavelength
- High frequency
- High energy
Which materials can x-rays penetrate?
Materials that absorb or reflect visible light
How do x-rays cause direct tissue damage?
By direct interaction with DNA
How do x-rays cause indirect tissue damage?
By the ionization of water molecules leading the formation of radicals
Which tissues are more affected by x-rays?
List 3
- Bone marrow
- Epithelial cells of the GI tract
- Early stage embryonic cells
What are the 2 classes of biological effects of x-rays?
- Stochastic effects
- Deterministic effects
Define stochastic effects
Give one example
Effects that have a random probability of distribution, and cannot be predicted precisely
Cancer or genetic effects
Define deterministic effects
Give one example
Effects that happen because of certain known conditions
Erythema, hematopoietic damage or cataracts
What does ALARA stand for?
As low as reasonably achievable
What are the units for absorbed radiation?
Gray (Jkg-1)
What are the units for effective dose of radiation?
Sievert
Define radiation exposure
Amount of ionization per mass air
Define absorbed radiation
Amount of energy transferred by radiation per mass
Define effective dose
A measure of radiation and organ system damage in humans
I.e. doses that are NOT received as a patient
What is the annual dose limit of radiation for the public vs a professional?
Public: 1mSv
Professional: 20mSv
What are 3 exceptions for the UK Veterinary Radiation Protection Regulations?
I.e. when can you go in to manually restrain the patient?
- Critical illness in which sedating the animal is dangerous
- Specific radiographic technique is required
- Patient type (i.e., large animal)
List 6 methods of radiation protection
- Filtration of the x-ray tube
- Time
- Distance
- Sheilding
- Collimation
- Personnel monitoring
What is the inverse square law when relating to the distance of radiographic imaging?
If the distance from the primary source is doubled, the intensity will decrease by a factor of four
List 3 ways you can sheild yourself from radiation
- Lead gloves
- Lead aprons
- Lead thyroid collar
What is a collimator?
A light beam diaphragm (like a view finder)
What are 2 types of dosimeters?
- Film badge
- Thermoluminescent (TLD)
How are x-rays produced?
Through conversion of kinetic energy of accelerated electrons into electromagnetic radiation
What is the source of electrons in an x-ray?
A cathode