Exam 1.5: Radiation Biology, Safety, Infection Control Flashcards
What are the three effects of radiation on atoms and molecules
Excitation
Ionization
Breakage of Molecular Bonds
What happens to an electron when it is excited by an xray photon?
It vibrates before returning to its normal state, releasing the energy stored from the impact as heat or light
How could radiation create an ion pair?
A high energy photon can impact an atom and eject an orbital electron creating a positive ion and a free electron….an ion pair
Why is molecular bond breakage the worst type of radiation damage?
It renders the molecules useless and can kill the organelle, which might lead to cell death
What free radicals are created via radiolysis of water?
OH* and Hesi
Can then react with water to form
HO2
H2O2
Besides water, what other common biological molecules can be turned into free radicals when hit with radiation
CO2
NO2
O2
What is a DIRECT effect of radiation exposure?
Ionization energy is placed directly into critical molecules within the cell
What is the critical biomolecule?
DNA
What is the INDIRECT effect of radiation exposure?
The water in the cell is radiolysed creating free radicals and toxic chemicals (H2O2) that then damage critical molecules like DNA and proteins
What is the period between the radiation exposure and the damage incurred by indirect effects?
Latent period
What are some health problems caused by the accumulative effects of radiation exposure?
Cancer
Cataracts
Birth defects
What factors of the radiation influence the radiobiological effects of radiation exposure?
Type of Radiation LET (Linear Energy Transfer) Total Dose Penetrating ability/Quality of Beam Local area v. Entire body
How do Alpha particles and X-rays compare in terms of LET?
Alpha particles have a High LET
X rays have a low LET
What host factors influence the radiobiological effects of radiation exposure
Species Intrinsic resistance Type of Tissue Rate of cell division Somatic Tissue vs. Genetic Tissues
What are the worst tissue cells to get hit with radiation?
Reproductive
Bone Marrow
GI Mucosa
What are the “best” tissue cells to get hit with radiation?
Muscle
Nerves
What are 4 Deterministic Effects
Erythema and Skin Ulcers
Epilation (Hair falls out by the roots)
Cataract Formation
Sterility
What is the term for genetic effects of radiation
Stochastic effects
What are the 4 Total Body Irradiation Syndromes
CNS Syndrome
GI Syndrome
Bone Marrow Syndrome
Lethal Effects
Which syndrome requires a threshold of 50+ Grays?
CNS (Neurons are able to take a lot of radiation)
What syndrome is imparted with 10-50 Grays
GI Syndrome
No cases of survival with doses of 10+ Grays
How much radiation is required to acquire Bone Marrow Syndrome
2-10 Grays
What percent of the average americans annual radiation comes from medical x-rays?
11%
What percent of the average american’s annual radiation comes from radon in the ground?
54%
How much radiation is the average american exposed to in one year (in microSieverts)
3000 uSv
How many microsieverts is in one Panoramic Radiograph
7 uSv
What are the chances of increased cancer risk from a dental x-ray?
1 in 1 Million Billion
What is the difference between exposure and dose?
Exposure (R) is the amount of radiation coming out of the machine
Dose is the amount of radiation that was absorbed by a unit mass of tissue
What do you need to multiply the dose by to get a effective dose measurement?
The quality of the beam.
Xray multiplier = 1
Neutrons = 5
Alpha Particles = 25
What is the MPD for the dental team for a year?
50 mSv
What is filtration
Removes soft, low wavelength x-rays that will contribute to the patient’s dose w/o contributing to the image
What do dental units operating at 70 kVp or more need in terms of filtering?
2.5 mm of aluminun
How does collimation help limit dose?
It restricts the beam’s cross-sectional area
What is the size of the beam diameter limited by federal law?
7 cm
How does a collimator also improve the image?
Reduces fog
Why is a long BID preferred?
Long BID’s reduce patient radiation exposure by reducing the amount of beam divergence so a smaller cross section of patient tissue is exposed per image
Why aren’t pointed plastic cones recommended?
They produce more scatter than a rectangular collimated beam
Why should you NEVER hold the tubehead in order to keep it steady during an image
A small amount of leakage will always sneak out of the tube head.
At what angle and distance should you stand from the primary beam to reduce occupational exposure
90-135 degrees and at least 6 feet away
What is the PPE needed for dental radiology
Mask
Gloves
What should be covered with plastic wrap to prevent contamination
BID
Yoke
Tubehead
Control Panel
What film speeds can be ordered pre-wrapped in bags
D
E
F
What is required for infection control in panoramic radiography?
Bite block cover or disposable bite block
What device can eliminate the need to cover the exposure button in plastic wrap
Foot switch
What must any contaminated, unwrapped items in the xray operatory be disinfected with
Quaternary ammonium spray solution
Spray Wipe Spray
28 days
