Safety Flashcards
cell biology
animals stay alive by dividing their cells
- mitosis: most cells
- meiosis: genetic cells
- energy in radiation disturbs natural sequencing
- primary effect on cells due to interaction b/w fluid in body + radiation
- radiation is cumulative **
radiation effects
1) stochastic: by chance, can occur without threshold level dose
- late-term effects appear many years after exposure/as genetic effect mutating offspring
- commonly causes cancer, cataracts, hyper/hypothyroid, sterility
- most at risk: eyes, thyroid, reproductive organs
- Clarence madison dally: first man to die from radiation
- marine curie died of radiation induced cancer
2) deterministic: noticeable in short term
- rare
- commonly cause erythema (skin reddening)
DNA effects
- radiation effects mainly present in cell DNA
1) radiation may pass through cell and not affect critical point, suspending mitosis but not damaging cell
2) cell may display no immediate effects but internal damage occurred that presents later during mitosis - cell division unsuccessful and cell dies
3) obvious cell damage, portions of DNA compromised
4) cell death, severely damages molecules
radioactivity
- atoms that exist in abnormally excited state w/unstable nucleus
- radiographic decay/disintegration
- important in nuclear medicine
intensity of radiation
- LET (linear energy transfer): amount of energy imparted on target, measures rate energy is transferred from ionizing radiation into patient’s tissue
- high LET = more energy transferred (-> reduces ability of particle to penetrate tissue -> increases risk of damage to target material as energy is absorbed in tissue)
- higher kV = higher energy beam = more energy scattered + secondary radiation = higher risk to worker
- important to know your settings! kV optimized to penetrate and mAs set to provide correct density
dosimeters
- captures radiation from xray, beta and gamma radiation, maintained until read by dosimetry service annually
- replaced at specific time intervals to be read
- should be kept in contained received in mail and stored away from radiation exposure
- users must provide personal info to dosimetry service
types:
- thermoluminescent (TLD): measures intensity of light emitted from crystal within detector when crystal is heated (intensity of light depends on radiation exposure)
- optically stimulated luminescence (OSL): has sensitive elements that absorb radiation and store energy in form of excited electrons
rules:
- don’t take home
- store away from radiation
- store away from heat/sunlight
- worn only at site it is registered to
- worn between waist + shoulder
- never shared
- not worn on coats that might be removed and hung in radiation area
- 2nd one needed on thyroid collar during fluoroscopic exams, must be clearly marked
- visitors need to be provided w/one
- facilities must post results of readings
dose limits
- employer’s responsibility to protect worker
- OHS has legislation
maximum permissible dose:
- the amount of radiation that doesn’t involve greater risk to technologist or future generations
- determines if procedures + equipment are adequate to provide the degree of protection necessary
radiation units
- radiation absorbed dose (RAD) measures amount of radiation absorbed per unit of mass (concerns biological effects)
- radiation equivalent man (REM)/dose equivalent: unit measured by dosimeters
- measured radiation (roentgen): dose output of x-ray, measured by service personnel calibrating unit
principles of protection
ALARA: as low as reasonably achievable
3 cardinal rules:
1) time (reduce time of exposure)
2) distance (increase distance b/w source of radiation + subject)
3) shielding (place shield/barrier between operator + source
- particular risk to anything actively developing + growing/cells rapidly dividing (pregnancy)
protective devices
- patient: laded drapes/shields
- cassettes: leaded dividers to lower scatter
- operator: leaded gloves, aprons, thyroid protectors minimum (goggles also recommended, movable barriers)
use + care:
- aprons hung by shoulders, do not fold
- clean w/warm water + gentle soap
- ensure correct fit
immobilization equipment
used for patient restraint
- foam blocks, cloth restraints, tie down
- any person helping restrain needs to be wearing PPE
- always use as few people as possible
dark room safety
tripping hazard
inhalation hazard
contact hazard
