Unit 3 Flashcards
Who is declared as a radiation worker
Anyone who may receive a dose of more than 1/20th of the of the whole body dose limit to radiation workers (more than 1mSv)
- must wear personal dosimeters
How often are dosimeters sent in for reading
Quarterly
Why is the radiation DL higher for radiation workers than the public
- workforce in radiation related dose is small compared to whole population
- doesnt alter the genetically significant dose
Distance and personnel dose
Distance is the most effective means of protecting from ionizing radiation
application of the inverse square law
- mobile unit exposure switch cord must be atleast 3m long from the tube
- radiographer should stand at a right angle to the x-ray beam wearing a protective apron if no protective barrier available
Time and personnel dose
- rotational schedule of personnel reduces the length of time personnel is in the path of radiation
- fluoro, interventional, mobile, general rad, c-arm fluoro
Shielding vs personnel dose
- used when its not possible to the use the principles of time and distance
Dose reduction techniques
- avoid repeats
- filter x-ray beam, reduces scatter
- always use adequate collimation
- technical exposure factors, higher avg energy increases forward scatter and less side scatter, lower mAs leaves fewer photons to produce compton scatter
Types of Shielding for personnel
- wall/barrier & control booths made of lead concrete and lead glass, location of control booth should be in a location where xrays need to scatter twice before entering control booth
- aprons gloves thyroid shields made of lead or rubber for operator or patient
Controlled vs uncontrolled areas
- controlled area for only occupationally exposed areas (Same as radiation DL for occupation)
- uncontrolled areas for public and others (1mSv/yr)
Direct radiation exposure
- direct radiation exposure should never be allowed
- cannot hold IR and should not hold patient
- pregnant operators are never permitted to hold patient during exposure
Primary Barriers
always try to point the beam towards primary barriers or unoccupied areas
- wall where primary beam is likely to hit (Bucky wall or XTL wall)
Secondary Barriers
never expose a secondary barriers with primary radiation (control booth)
Lead thickness equivalency
- must be permanently and clearly marked and tested yearly
- stored maintained to manufacturers intstructions (do not fold aprons)
- 100kV or less lead Eq. must be 0.25mm
- 100kV-150kV lead Eq. must be 0.35mm
- 150Kv or more lead Eq. must be 0.5mm
Bucky Slot Shielding
When bucky is pushed all the way to the side lead covers the hole to prevent scatter
Lower potential scatter dose when Fluoroing
The location of the lower
potential scatter dose is on the
side of the patient away from
the x-ray tube (i.e., the image
intensifier side
Lateral Set up for Fluoro
Standing on patient side away from the tube (beside image intensifier)
Regulations that concern operator safety
SC35 2.0-2.4
Preparing for fixed fluoro procedure which has tube under table list all possible ways you can be protected from exposure
- bucky slot shielding
- lead lined curtain
- lead apron/thyroid collar and glasses
- TLD
