Practical Radiation Safety Flashcards
How to reduce radiation exposure
Limit Time,
Increase distance,
Use shielding
These principles help minimize radiation exposure.
What should be done to limit exposure time when using fluoroscopy?
Limit exposure time by using pulsed exposure if possible
This reduces the dose received by patients and operators.
What happens to the radiation dose when the distance from the source is doubled?
The dose decreases
As distance from source increases
Doubling the distance reduces the area over which radiation is spread.
In fluoroscopy, how should the x-ray tube be positioned relative to the patient?
Position the x-ray tube as far from the patient as possible
Must be at least 30 cm from the patient’s skin.
Position detector as close as possible to the patient
What is the definition of Half Value Layer (HVL)?
The thickness required to reduce the dose to half what it is without the attenuation
HVL is crucial for radiation shielding.
What materials are typically used for radiation shielding at lower diagnostic energies?
Lead
Lead has a high atomic number (Z) and is effective at these energies.
Photoelectric effect occurs- Hugh atomic no. And high frequency
What is the primary concern regarding scatter radiation in fluoroscopy?
Most scatter is directed back towards the x-ray tube
This affects the positioning of the x-ray tube during procedures.
Stand opposite side of the x-ray source to prevent scatter exposure
What type of personal protective equipment (PPE) will not protect you from the primary radiation beam?
Lead gloves
Lead gloves protect against scattered radiation, not the direct beam.
True or False: PPE is effective against the primary radiation beam.
False
PPE should never be relied upon to protect from the primary beam.
When should you notify radiation safety
Dosimeters is lost or damaged
Doses are above investigation levels
Staff member is reaching an annual limit
This is crucial for maintaining safety records.
What is the purpose of a dosimeter?
Form of PPE
To measure the amount of radiation exposure
They do not protect from radiation but record exposure levels.
Have a duty to use them and take care of them
What is the advantage of thermoluminescent dosimeters (TLD)?
They emit light when heated
TLDs can provide a permanent record of exposure.
Small devices
Can be worn on fingers
Reusable
What happens to the dose received by staff when changing to a fluoroscopy low dose setting?
The dose is reduced by 50%
This significantly decreases radiation exposure during procedures.
What is the effect of collimating the beam to a smaller size?
It reduces the dose received
For example, collimating from 10 cm x 20 cm to 10 cm x 10 cm can halve the dose.
What is the impact of increasing distance from the radiation source on exposure?
It reduces the dose significantly
For instance, standing at 100 cm instead of 50 cm can reduce the dose by 90%.
What should be done with lead aprons to ensure they remain effective?
Store them appropriately to limit creasing
Proper storage prevents damage and maintains their protective qualities.
True or False: It is acceptable to pierce or bend a dosimeter.
False
Damaging a dosimeter can result in inaccurate readings.
What is the advised maximum dose limit for fingers in the primary beam?
100 minutes for an entrance dose rate of 20 mSv/min
This limit is crucial for preventing occupational exposure injuries.
What should be included in a PPE inventory?
Lead aprons, thyroid shields, and individual labels
This ensures accountability and proper maintenance.
‘Acquisition’ meaning
Step back due to radiation dose
Lead gloves and primary beam
Keep your hands well away from the primary beam
Lead gloves are not designed to protect hands from the direct beam. (Only scattered radiation)
You should never enter the primary beam
All operators fingers in the beam must be datixed
Wearing lead gloves in primary beam causes detector to pump up dose to get through the lead which pouts operator in higher danger
Rad pads
Radiation protection shield that is placed directly over patient and gives operator protection from the scattered radiation
Ceiling mounted screens
Use wherever possible
Place as close to the individual
Film badges pros and cons
Pros:
Cheap
Permanent record
Range of doses
Acute or chronic exposure
Cons:
Not very sensitive
Can be fogged by heat
Larger than TLD
No longer routinely available
