Radiation Biology Part 4 Flashcards
what are the goals for oral and maxillofacial radiology
- reduced radiation exposure
- maintain a high degree of diagnostic efficiency
what does ALARA stand for
as low as reasonably achievable
what factors are prioritized in ALARA
- time
- distance
- shielding factors
what are the MANDATED dose reduction mechanisms for the X ray tube head
- filtration
-collimation
what is filtration and what does it do
- selective passage of contents through a specified substance
- selectively removes a greater proportion of low keV x ray photons
- increases mean energy of the beam
what is the mandated minimum total aluminum filtration for <50 kV
-0.5mm
what is the mandated minimum total aluminum filtration for 50-70 kV
1.5mm
what is mandated minimum total aluminum filtration for >70 kV
2.5mm
what is the maximum diameter of the exit side beam collimation and what shape is preferred
2.75 inches
- rectangular preferred
what are the optional dose reduction mechanisms for X ray tube head
- rectangular collimator
- high kV generator/transformer
- constant potential (DC) fully rectifiied
- increased focal length
what is the name of another device that uses a rectangular collimator
Tru-align
area exposed is related to the:
maximum size of the beam
effective dose is relative of:
the specific technique
higher kV units are:
larger and heavier
higher kV = _____ dose
lower
what are the benefits of constant potential (DC) fully rectified
- high detail and sharp X rays with 20-30% less radiation
- increased diagnostics with variable tube voltage due to a 60-70 kV DC multi pulse generator
increase of long BID benefits:
- 27% less head volume
- reduced effective dose
- sharper image
what are the dose reduction mechanisms practice options
- film speed
- lead Pb thyroid collar
- film holding devices with beam alignment capability
- time- temperature quality control processing
what are the film speeds
- D speed (ultraspeed)
- E speed
- F speed ( insight)
- digital receptors: PSPP, CCD, CMOS
what are the ways we protect patients
- lead apron
- thyroid collar
what are the patient shielding recommendations during dentomaxillofacial radiology
1: discontinue shielding of the gonads, pelvic structures, and fetuses during all dentomaxillofacial radiographic imaging procedures
2: thyroid sheilding not used during intraoral, panoramic, cephalometric and CBCT imaging
where should the operator be during an exposure taken with a wall mounted X ray unit
-behind a protective barrier
- if protective barrier not present, stand at least 6 feet from the patient at an angle between 90-135 degrees to the direction of the useful beam
what should the operator never do
- stand in the primary beam
- hold film or other receptors in a patient’s mouth
what needs to be worn by all full time operators of radiographic equipment while x ray exposures are being made
dosimeter badges
