Radiography Principles

Study Notes

The substance of which a physical object is composed is known as matter.
Potential energy describes the ability of an object to do work by virtue of its position.
Electromagnetic energy exists in 2 forms: ionizing radiation and nonionizing radiation.
X-rays are invisible, have no mass, and produce electric and magnetic fields.
A neutron can travel a great distance and typically requires a hydrogen shield to contain it.
Radiation quantity is governed by the voltage used and regulates the x-ray penetrability of the beam. This statement is true
Compton scatter is responsible for the majority of scatter produced during diagnostic imaging.
Erythema is the most commonly observed effect of radiation exposure.
Symptoms of hematologic syndrome include all of the following except constipation.
Symptoms of central nervous system syndrome include ataxia, meningitis, and systemic vasculitis
The primary stochastic effect observed in humans is cancer.
Radiographers use time, distance, and shieling to enact ALARA

As x-rays pass through matter, they dislodge electrons, creating an ion in an atom or molecule.
The simplest form of an element that retains that element's chemical properties is an atom.
The cathode assembly consists of the filament wires, a focusing cup, and associated wiring
Bremsstrahlung x-rays are produced when an incident electron interacts with the force field of the target atom's nucleus.
A photon is sometimes pictured as a small bundle of energy that travels through space at the speed of light.
X-rays are an example of low-linear energy transfer radiation.
The amount of energy retained by a scattered x-ray depends on the energy of the original x-ray and the angle of deflection.
Equivalent dose is the product of the average absorbed dose in a tissue or organ and its associated radiation weighting factor.
Five millisieverts is the recommended dose limit by the National Council on Radiation Protection and Measurements for cumulative exposure to members of the public who are frequently exposed.
Cardiovascular and central nervous system acute radiation sickness occurs with doses of 30 Gy or more.
Advantages of thermoluminescent dosimeters include being more sensitive and accurate than film badge dosimeters and they can be read on site
Ways to reduce patient dose during fluoroscopic procedures include using electronic collimation, performing fluoroscopy intermittently, and using the last image hold feature.

Somatic effects of ionizing radiation exposure include that they can be short- or long-term, and the most detrimental long-term effect is the increased probability of developing cancer..
Deterministic effects typically result from high-dose exposure during a short period.
Of the sources of radiation mentioned the patient is associated with the highest level of exposure..
When distance from a radiation source doubles, radiation intensity decreases by a factor of 4.
The minimum lead-equivalent thickness apron that should be worn during fluoroscopic procedures is 0.5 mm.
When performing mobile radiography, radiologic technologists should stand at least 6 feet away from the x-ray tube, and wear a protective apron with a minimum of 0.25-mm lead equivalency.
Ceiling-suspended shields can decrease scatter radiation to the head, lenses of the eyes, and neck of imaging personnel by 50% to 60%.
Whole-body dosimeters should be worn at the vertical midline at collar level, outside the lead apron.