Radiation Protection Quiz to Final Review Flashcards
What is used to assess the impact of gonadal dose?
GSD: genetically significant dose
Temporary sterility can occur in males and last as long as 12 months with a dose of _________?
2Gy
What is the most pronounced effect of exposure within the first weeks of fertilization?
Prenatal death, very rare
3 major considerations when constructing a radiology departments protective barriers
- location in institution
- barriers
- adjoining rooms
What about location in the institution must be considered ?(protective barriers)
- basment, main floor, upper floor: kind of clients, size of elevators
- infrastructure in the existing or new department
2 common materials for barriers
- lead
- concrete
What can good communication with the patient do?
- Reduce anxiety and stress
- Increase chances of successful x-ray
4 types of patient shield. Describe
- Flat Contact shield: made of lead strips 1mm thick. Most effective for AP
- Shadow Shield: radiopaque material hang over the area of clinical interest to cast a shadow in the primary beam over reproductive organs
- Clear Lead Shield: transparent lead. Organic material impregnated with 30% lead by weight
- Shaped Contact Shield: contoured to enclose the male reproductive organs
Design of an x-ray room rules
- Adequate working space for tech
- SHOULD be self closing door, but MUST have “unauthorized entry prohibited” sign
- no one can enter the room without the tech knowing
- beam only directed towards primary barriers
- wall detectors must have primary shielding
- radiation must be absorbed as close to the patient as possible
- control booth and window are secondary barriers
- radiation must scatter at least twice before entering control booth
Another name for bone marrow dose?
Mean marrow dose
Calculating barrier thickness
- location of controlled vs. Uncontrolled areas
- max kVp
- distance from radiation source
- occupancy on other side of barrier
- use of unit or time tube is energized
- workload of unit
- intrinsic shielding (leakage)
What happens if an exposure is taken and the SID is too short? Too long?
Too short: overexposed, may need to repeat
Too long: underexposed, may need to repeat
Lead apron specs for pregnant staff
90% attenuation at 75 kVp
Controlled areas maximum exposure according to SC35
20mSv/yr
What must be considered about adjoining rooms? (Protective barriers) and 2 types of adjacent rooms
- amount of time occupied
- type of occupancy
- controlled
- uncontrolled
Irradiation of an unborn fetus increases risk of ________ and _______ effects.
- somatic
- genetic
0.1mm lead =
- 0.5mm steel
- 1.2mm glass
- 2.8mm gypsum
- 19mm wood
Use factors (from chart)
Primary Barriers:
U=1: full use, floor of radiation room, walls near upright detector, any walls/door/ceiling exposed to direct beam
U=1/4: partial use, door and wall areas not normally exposed to direct beam
U=1/16: occasional use, ceiling areas not normally exposed to direct beam
Secondary Barriers:
U=1: full use, scatter emerges in all directions
Who do you contact if the patient in unsure about pregnancy status
Referring physician
Most common SIDs for technique charts in Canada?
100, 110, 150, 180cm
ESE
Entrance skin exposure
When are the ovaries most radiosensitive? Least radiosensitive
Fetal stage, childhood, and after approx. 30yrs old until menopause
Least radiosensitive from 20-30 yrs old
7 methods to reduce patient dose
- shielding
- collimation
- technical factors
- Quality control
- equipment
- communication
- filtration
What is included in a Radiation survey report?
- Schematic of location, equipment, booth, and surrounding areas
- Equipment identification and type of tube support
- Observation of electrical and mechanical operation
- Actual or estimated total workload
- Result of radiation readings, both in and outside of controlled area
- Estimate of potential exposures
- Assessment of equipment, techniques, DRLs, restraints, filtration
- recommends improvements
What is the first and most important step in gonadal protection?
Collimation
Most genetic mutations are _______?
Recessive traits: both male and female must have the gene for it to be produced
Primary barrier materials
- Lead bonded to sheet rock or wood panelling
- Concrete, cinder blocks, or brick
1/16th” lead = 4 inches of brick
0.4mm lead = 24mm concrete
What is the role of the responsible user?
- Monitor and manage safety programs
- Implement image quality assurance program
- Oversees equipment safety and performance reports
- ensure equipment is used properly
- etc.
What is the occupancy factors? (T)
Takes into account the time that the space behind the barrier is occupied
SC 35 guidelines to exposing a pregnant patient
- exposure should be as low as possible
- shield if possible
- patient should be positioned prone- gets rid of softer rays
- don’t use x-rays to see position of fetus
- well collimated, well shielded, AP/PA and lateral views only
3 types of PBL
- Aperture Diaphragm
- Cones
- Cylinders
- (Variable Aperture Collimator)
Protective staff clothing should be tested ________ and must be tested ________
Should: semi-annually
Must: annually
ColEfD
- collective effective dose
- used when a population has been exposed by a radiation accident
- EfD of an individual x # of people
What things are taken into account when measuring fetal dose?
-x-ray unit used
-projection taken
-#of images
-exposure factors used
-SID
-patient measurements
For fluoro and spot films: also exposure time
Secondary barrier materials
- gypsum
- glass
- lead-infused acrylic
Who is ultimately responsible for radiation safety of the entire facility?
The owner
NCRP
National Council on Radiation Protection
-US corporation, determines how ICRP recommendations are incorporated into the US radiation protection criteria
What does quality control do?
Ensures production of optimal images
Uncontrolled area maximum exposure
1mSv/yr
-pediatrics 0.30mSv/yr
Purpose of radiation surveys?
Ensures the x-ray and auxiliary equipment is working within SC35 standards and adhered to radiation protection act of alberta
Ensured proper equipment installation and provides max radiation protection for everyone
4 major concerns in radiology and fetus exposure are?
- congenital abnormalities
- spontaneous abortion
- metal retardation
- childhood malignancy
Thickness of a barrier depends on_______?
- distance between the barrier and radiation source
- where the tube is situated when energized: upright, table, x-table
What is workload and Workload formula
mAs x (days/week) x (patient/day) x (films/patient)
Weekly radiation use of the unit (mA-min/wk or mAs/wk)
What is ESE?
Absorbed dose to the most superficial layer
EqD
- Equivalent Dose
- the biological effect of radiation type R having a radiation factor WR
What is use factor?
Fraction of workload when the beam is on and directed towards a barrier
How much mA-min/wk is classed as a busy radiology room? Slow room?
Busy: greater than 500mA-min/wk
Slow: less than 100mA-min/wk
When are primary barriers required?
Whenever the primary beam is directed at a structure
Rules for staff protection
- Decrease time in room
- Increase distance from tube and patient
- Always use shielding
- Never stand in the primary beam
- ALARA also applies to our exposure
What is the greatest radiation hazard to the tech?
Patients
What is an uncontrolled area?
- occupied routinely by other staff/general public
- bathroom, waiting room, change room
Permanent sterility in a males and females is most likely to occur with a dose of _______?
5-6Gy
What is GSD?
The EqD that can bring about genetic injury
7 methods to reduce patient dose
- Shielding
- Collimation
- Technical Factors
- Quality Control
- Equipment
- Communication
- Filtration
What happens if a fetus is irradiated in the first 2-12 weeks of development?
- skeletal and organ abnormalities
- central nervous system abnormalities
- neonatal death of abnormalities are severe enough
What is the ten-day rule?
X-rays should be taken in the ten-day period after menstruation begins because there is a low probability of pregnancy
EfD for occupational radiation exposure
- Whole body: 20mSV
- Eyes: 150mSV
- Skin, hand, and other organs: 500mSV
Minimum lead required in aprons
0.25mm
Occupancy Factors (from chart)
T=1: offices, labs, wards, nursing stations, living quarters, any other area that is normally occupied while the tube is energized
T=1/2: patient examination and treatment rooms
T=1/5: corridors, patient rooms, staff lounges, staff restrooms
T=1/8: corridor doors
T=1/20: public restrooms, vending areas, storage rooms, outdoor sitting areas, patient holding areas
T=1/40: outdoor areas with pedestrian or vehicle traffic, parking lots, drop-off areas, stairways, closets
Types of stationary barriers
- Primary barrier: absorbs primary beam
- Secondary barrier: absorbs misdirected scatter and leakage
3 ways patient dose can be established?
- ESE/ESD
- Gonadal dose
- Bone Marrow Dose
What are dose limits?
Dose of radiation that is not expected to produce a significant effect
Ways to protect staff from exposure
- mobile walls
- bucky slot shielding device
- image intensifier curtain
- radiologist
7 factors that need considering when determinin necessary shielding for a DI room
- Primary or secondary barriers
- Distance from radiation source (D)
- Occupancy Factor of the area (T)
- Controlled or Uncontrolled areas
- Workload (W)
- Maximum and average tube potential and output
- Use Factor (U)
3 types of radiation that may be in an x ray room
- scatter
- leakage
- primary
All radiographic rooms MUST have a detailed floor plan that indicates
- location of control panel: dimension, shape, size, location
- location of the equipment within the room
- range of movement of the tube
What is the outcome if an exposure is taken at an SID that is too short?
Overexposed, may need to repeat
2 methods to determine ESE?
- Nomogram: graph
- Calculations
Ideal kVp and mAs combo?
High kVp, low mAs
Another name for use factor?
Beam direction factor
What is used for the average kVp calculations of a room?
100kVp
Who calculates fetal dose after all the info is supplied to them?
Medical physicist
What is the purpose of protection standards groups?
To help to form recommendations for EfD and EqD
ESE helps the medical physicists approximate the fetal dose based on several factors (list factors)
- kVp
- mAs
- SID
- Beam filtration
- tube output per minute (in fluoro)
Two types of movement?
Voluntary and involuntary
Minimum amount of lead in protective equipment?
- Aprons: 0.35mm
- Shielded barriers: wall (0.3-2.0mm) hanging (0.5mm)
- Gloves: 0.25mm
- Glasses: 0.35
- Thyroid collars: 0.5mm
Maximum dose for fetus for entire pregnancy?
4.0mSv
ICRP
International Commission on Radiologic Protection
-international authority regarding the safe use of ionizing radiation
TEDE
- total effective dose equivalent
- lifetime effective dose
- age in years x 10mSV
9 Safety equipment requirements from SC 35
- Warning signs
- Markings
- Mechanical stability
- Indicator lights
- Indication of loading factors
- Irradiation Control
- Controlling Timer
- X-ray tube shielding
- X-ray beam filtration
How is the optimum technique for a patient determined?
- patient thickness
- composition
UNSCEAR
United Nations Scientific Committee on the Effects of Atomic Radiation
- provides help for radiation guidelines
- evaluates human and environmental ionizing radiation exposures
NRC
Nuclear Regulatory Commission
Types of radiation and how to calculate them
- primary radiation: total primary = mR/mAs x mA x time
- Scatter (secondary): mR @ patient x 0.1% @ 1m
- Leakage (secondary): must never exceed 1mGy/hr OR 100mR/hr @1m
NAS/NRC-BEIR
National Academy of Sciences/Nation Research Council Committee on Biologic Effects of Ionizing Radiation
-advisory group that reviews studies of biological effects of ionizing radiation and risk assessments
Shielding plans should take into consideration what 2 things?
- advances in radiation technology
- ALARA becoming stricter
What is the main priority of department design and safety?
-to protect the people from radiation exposure above current exposure limits
EfD
- Effective dose
- the biological effect of radiation on tissue types. Tissue having a radiation weighting factor WT
- measured overall risk of exposing body to radiation
Doses higher than ______ may deplete mature sperm (maturation depletion)
0.1Gy
10 specific radiographic equipment rules from SC 35
- Radiation output reproducibility: same exposure 10 times w/same output
- Radiation output linearity: different combos of mA and time
- Irradiation switch
- Automatic exposure control
- Current time product limit
- Accuracy of loading factors
- Minimum irradiation time capability
- Beam limiting devices
- Radiation/light field alignment
- Focal spot marking
What is the purpose of filtration?
‘Hardens’ bean by absorbing low energy photons, reduces patient dose
After puberty, doses as low as _______ may cause suppression and /or delay of menstruation?
0.1Gy
What is a controlled area?
- immediate areas where x-ray equipment is used
- occupied by monitored personel
- procedure rooms and control booth
Doses of _______ can cause temp. sterility in females?
2Gy
What is bone marrow dose?
Average radiation dose to all active bone marrow
Distance of the barriers depends on _________
The type of exposure the barrier receives
When calculating shielding, do we take into account the scatter from the patient?
No
4 methods to evaluate for and protect potential early pregnancies
- questions
- signs on doors and in change rooms
- elective bookings
- ten-day rule
What is the major contributor to gonadal dose?
Medical x-rays
