Filtration and Beam Restriction
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| Ability to image small objects that have high subject contrast. | show 🗑
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| show | Contrast Resolution
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| Image detail or visibility of detail | show 🗑
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| What are two principle ways of controling scatter radiation that reaches the IR? | show 🗑
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| show | kVp, field size, patient thickness
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| show | aperture diaphragm, cones and cylinders, variable aperture diaphragm (PBL)
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| show | Increased kVp will allow for more penetration of beam and there will be lower patient dose (due to less attenuation) but an increase in scatter and decrease in image contrast
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| By decreasing the field size you _______ the level of scatter radiation. | show 🗑
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| What is the simplest type of beam restricting device that is attached to the head of x ray tube? | show 🗑
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| Cones and cylinders | show 🗑
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| show | PBL - positive beam limitation (automatic collimation)
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| What is the main purpose of beam restriction? | show 🗑
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| If collimation is increase, what will happen to pt. dose, density and contrast? | show 🗑
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| If field size is increased (open up collimator), what will happen to pt. dose, scatter, density and contrast? | show 🗑
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| show | Problem with ghosting (shadow of anatomy)
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| Ghosting is due to what? | show 🗑
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| show | Between the anode and the patient
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| show | 8-9 penny test; checks for collimator cutoff
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| Entrance shutters | show 🗑
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| show | project light image onto patient; sits at a 45 degree angle and sits exactly between the light source and focal spot siz
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| Moveable lead shutters | show 🗑
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| show | Harden the beam to reduce patient skin exposure
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| Filters have an affect on scatter. T/F | show 🗑
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| show | aluminum or can be a combination of aluminum and copper
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| show | absorbs low energy, long wavelength radiation that contributes to skin dose and leaves higher nergy, short wavelength beam which has more penetration.
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| Where is the filter located? | show 🗑
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| Measurement of the amount of absorber required to reduce intial beam intesnity by 1/2 or 50%. | show 🗑
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| What is total AL filtration? | show 🗑
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| show | envelope (gas or metal; houses anode and cathode) and oil
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| What are the requirements for the mm AL used if the kVp range was less than 50? | show 🗑
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| show | 1.5 required
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| What are the requirements for the mm AL used if the kVp range was 70-100? | show 🗑
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| show | 3.0 required
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| What affect do filters have on image quality (contrast and density)? | show 🗑
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| What are two examples of compensating filters? | show 🗑
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| show | Even out density of body parts with unequal thickness
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| When radiating a foot how would you use the wedge filter? | show 🗑
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