Unit 2: Minimizing Exposure to the Patient Flashcards
Explain risk vs. benefit
The risk of being exposed to radiation versus the benefit of getting treatment/diagnosis
Must vs Should
must is a directive that needs to be followed should is a reccomendation that should be heavily considered
Define Genetically Significant Dose (GSD).
Radiatiion workers are such a small population that dose to us does not play a genetically significant role
2 best ways to minimize exposure to the patient
- communitcation: reduces anxiety and increases cooperation
- immobilization: voluntary or involuntary motion, motion causes blurred image and causes repeats
SID vs Dose
- maximizing SOD
- distance and centering indicators must be within 2% of the SID
- minimum SSD of atleast 30cm
PA/AP vs Dose
- reduction of low energy photons hitting the gonads in a PA position
Collimation devices vs dose
- limiting the primary beam before it enters the area of clinical interest
- significant reduction of dose
- improves overall quality of the image
- positive beam limitation, automatic collimation to the size of the IR
- yearly SC35 checks collimation and light beam congruency
Protective Filtration vs. Dose
- aluminum most commonly used to effectively remove low energy photons
- HVL: decrease the intensity of the primary beam by 50% of its initial value
- Compensating filters like boomerangs to make the body part being imaged uniform in density
Grids vs Dose
- ## grids cut off scatter radiation to improve image quality
Shielding vs Dose
- should always be used
- must have a lead equivalency of 0.25mm and examined yearly
Optimum Processing vs Dose
- Correct image post-processing is essential to produce a high-quality
diagnostic image in which artifacts produced by the IR, software, or patient-related problems are controlled - Repeat rates in DR: eliminates the need for almost all retakes
required because of improper technical selection, because image
contrast and overall brightness may be manipulated after image
acquisition
IR sensitivity vs Dose
- increased sensitivity reduces the dose
- Higher DQE
kVp, mA vs Dose
high kVp low mAs to reduce dose
Total Filtration
- added filtration
- inherent filtration
Why is diagnostic tube housing required
- photons shoot in all direction thus lead lined housing absorbs any unnessecary photons (leakage radiation)
- 1m away from the housing should be a level of 100mR/hour of leakage radiation
What does more protective filtration have
- harder x-ray beam
- higher average energy
- less soft or low energy photons
Fluoroscopy equipment configurations for patient and operator safety
- having the tube below the table is best of patient and operator dose
- makes patient PA
- having lead apron blocks scatter from patient hitting operators legs (typically when AP scatter hits upper apendages of operator)
- having the tube below the table with max SSD reduces skin entrance dose
SSD distance & Fluoro safety
Image intensifier should be maintained as close as possible to reduce the patients entrance exposure rate
- requirements: Source no less than 38cm for stationary fluoroscopes and 30cm for mobile fluoroscopes
Filtration and Fluoro safety
(HVL for 80-100kVp)
HVL of 3.5-4mm of aluminum is acceptable with kVp ranges from 80-100kVp
Mag mode of image intensifiers
changes where the focal spot is adds magnification and patient dose
Intermittent mode vs Dose
Pulsing exposure reduces dose in long procedures
Culmulative timing device
Every 5 mins an alarm would sound
- keeps person fluoroing focused
- need to document time fluoro was running for
Radiation Safety measures for fluoroscopy
- limiting field size
- dead man switch on control panel (deactivates as soon as it is let go)
- timing device
- pulse mode
- mag mode
ESE - entrance skin exposure
- ESE) is the measurement of radiation output at the point of skin entry for
common X-ray examinations, including fluoroscopic and conventional
radiology - C/kg or mR or mGy
