Bushong (9th; Ch 9)
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| A measure of the number of ion pairs produced in air by a quantity of x-rays | roentgen (R) or
milliGray [subscript a] (mGya)
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| the number of x-rays in the useful beam | x-ray quantity
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| X-ray intensity of most general purpose radiographic tubes, when operated at approx. 70 kVp | 5 mR/mAs (50 μGya) at 100cm SID
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| Units of x-ray intensity | roentgens (R), mGya, mR/s, mR/min, or mR/mAs
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| X-ray quantity or intensity; measured in roentgens (R) | radiation exposure
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| radiation ________ = x-ray _________ = _____ quantity | exposure; intensity; x-ray
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| x-ray ________ is ________ proportional to the mAs | quantity; directly
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| a measure of the total number of electrons that travel from cathode to anode to produce x-rays | milliampere seconds (mAs)
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| a measure of the electrostatic charges; 6.25 x 10¹⁸ electrons | Coulomb (C)
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| Formula for x-ray quantity & mAs | I₁/I₂ = mAs₁/mAs₂
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| Formula for x-ray quality & kVp | I₁/I₂ = (kVp₁/kVp₂)²
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| X-ray ________ is ____________ to the kVp² | quantity; proportional
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| mC = ___ | mAs
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| For optical density to remain constant, if kVp is increased by ___ then mAs should be _______ by ½ | 15%; reduced
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| X-ray quantity is _________ proportional to the square of the ________ from the ______ | inversely; distance; source
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| X-ray intensity varies _________ with the ______ of the ________ from the x-ray tube ______ | inversely; square; distance; target
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| Formula for x-ray quantity & distance | I₁/I₂ = (d₂/d₁)²
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| Square Law | mAs₁/mAs₂ = (SID₁)²/(SID₂)²
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| When SID is increased, ___ must be increased by ____ to maintain constant exposure to the IR | mAs; SID²
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| Purpose of filters | reduce number of low-energy x-rays
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| Commonly used metal filter | 1-5mm Al
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| Adding __________ to the useful x-ray beam reduces _______ ____. | filtration; patient dose
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| Disadvantage of ↑ kVp & ↓ mAs for OD to remain constant | ↓ image contrast
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| Disadvantage of added filtration | ↓ image contrast
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| increases the number of high energy x-rays in the beam by removing the lower-energy nonpenetrating x-rays | beam hardening
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| one description of the ability of x-rays to penetrate deeper in tissue | penetrability
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| the penetrability of an x-ray beam | x-ray quality
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| X-rays of any given energy are more penetrating in material of ____ atomic number than in material of ____ atomic number | low; high
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| the reduction in x-ray intensity that results from absorption & scattering | attenuation
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| the thickness of absorbing material necessary to ↓ reduce the x-ray intensity to ½ of its original value | Half-value layer (HVL) of an x-ray beam
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| HVL of diagnostic x-ray beam | 3-5mm Al, or
3-6cm soft tissue
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| the best method for specifying x-ray quality | HVL
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| X-ray beam quality can be identified by _______ or __________, but ___ is most appropriate | voltage; filtration; HVL
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| Atomic number of aluminum (AL) | 13
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| Atomic number of gadolinium | 64
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| Atomic number of holmium | 67
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| Atomic number of copper (Cu) | 29
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| Atomic number of tin | 50
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| Increasing the ___ peak _________ the quality of an x-ray beam | kVp; increases
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| Amount of total filtration | 2.5mm Al
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| Increasing filtration increases the _______ of an x-ray beam | quality
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| Atomic number of Beryllium | 4
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| ↑ filtration = ↑ beam _______ = ↓ beam ________ | quality; quantity
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| part of the glass or metal enclosure of an x-ray tube through which x-rays are emitted | window
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| reason why window is thin | provides for low inherent filtration
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| type of filtration provided by the glass or metal enclosure of an x-ray tube; filters emitted x-ray beam | inherent filtration
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| inherent filtration of a general purpose x-ray tube | 0.5mm Al equivalent
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| type of special purpose tube with very thin window | mammography
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| inherent filtration of mammography unit | 0.1mm Al; sometimes made of Beryllium rather than glass
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| Added filtration results in ↑ ___ | HVL
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| Added filtration resulting from the silver surface of the mirror in the collimator | 1mm Al equivalent
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| material inserted between an x-ray source & a patient to shape the intensity of the x-ray beam; an x-ray beam filter designed to make the remnant beam more uniform in intensity | compensating filter
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| special filters used with CT imaging systems to compensate for the shape of the head or body | "bow-tie"-shaped filters
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| type of filter sometimes used in chest radiography; thin region over mediastinum & thick portions lateral over lung fields | bilateral wedge filter; trough filter
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| type of filter applicable to digital fluoroscopy, where the IR, the image intensifier tube, is round; can be concave or convex | conic filters
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| type of filter that compensates for OD variation of body parts that vary considerably in thickness | wedge filter
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| type of filter used in special procedures involving long sections of anatomy on 2 or 3 separate IRs | step-wedge filter
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