Ch. 2 - Radiographic Techniques Flashcards
What are the three basic principles of radiation protection?
Justification Principle, Limitation Principle, and Optimization Principle
The Justification Principle
The Justification Principle: this principle states that one should expose patients to ionizing radiation only if there is no other way to obtain the diagnostic information or if this exposure will positively influence the diagnosis, the treatment, and the patient’s health
The Limitation Principle
one should always try to keep the radiation dose as low as reasonably achievable (ALARA)
The Optimization Principle
The Optimization Principle: one should obtain the best quality images possible, with both previous principles in mind
The purpose of adhering to the radiation protection principles
X-rays can impart energy to the matter they traverse; if that matter is living tissue, then some biological injury may occur
Little is known about the effects of low-energy ionizing radiation (as used in diagnostic radiology and dentistry in particular) on biological systems
Assumptions of damage are based on extrapolation of data from high to lower levels of radiation
What are the two models that explain the effects of radiation?
Non-Threshold (stochastic) Model:
any dose of x-rays can cause biological damage
Threshold Model:
No detrimental effects of ionizing radiation occur below a particular level or “threshold” of x-ray exposure
What does ALARA stand for? and what radiation protection principle is it part of?
as low as reasonably achievable (ALARA); justification principle
what is deterministic effect
a certain amount of radiation is necessary before the response can be seen; Carcinogenesis and malformations are responses of somatic tissues and are believed to have a threshold response
how and where should the radiographer stand when tkin
The radiographer should stand either at 90° to or behind the radiation source; at least 6 feet (2 meters) from the radiation source is safe
Focus-to-skin distance definition and distance?
Focus-to-skin distance = distance between the x-ray machine’s anode (where x-rays are created) and the skin of the patient’s cheek or lip
Ideally this should be a minimum of 8 inches (20 cm) to reduce the amount of low-energy x-radiation reaching the patient
When is the use of a lead apron is not necessary ?
ICRP guidelines suggest that the use of a lead apron is not necessary with rectangular collimation, short exposure times, adequate x-ray energies, and fast image receptors.
what are PSPPs?
photo-stimulable phosphor plates (PSPPs)
