Usual Operations
Page 5-30
5.4.2. General Dose Planning
There are several dose reduction measures available in the system. They are: Low Dose Mode, Pulsed Mode
using reduced frame rates, removal of the contrast grid, and additional filtration.
As a general guideline, Low Dose Mode will typically reduce the dose by 50%. This will typically result in
reduced image quality.
Pulse Fluoroscopy can result in dramatic dose reduction where image update frequency is not critical.
Images may be noisy /grainy, especially in dense anatomy. The slowest pulse rates provide the
greatest dose reduction. Clinical need should determine the appropriate pulse rate.
Contrast grid removal is not recommended for anatomical thickness greater than 20 cm, although this
is where the greatest dose reduction would occur, but this would also result in the greatest loss of
image quality.
Added filtration is recommended for all pediatric applications. Dose reduction will be greatest for light
anatomy and will result in some image contrast reduction.
It may be possible to use these dose reduction features in combination, resulting in even greater dose
reduction. However, there will be incremental image quality reduction for each dose reduction feature.
It is not advised to remove the grid for anatomy greater than approximately 15 cm in thickness, since
image contrast can be severely impacted. Narrowing the beam through collimation will help minimize the
effects of scattered radiation on image quality. This also reduces the exposure area on the patient.
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