Part III Flashcards by Queenie Francisco

the degree of blackening in the finished radiograph

optical density

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OD is primarily controlled by [..]

mAs

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Optical and mAs relationship

directly proportional

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Tips for High Contrast-Short Scale of Contrast

Low Scatter Radiation
High Differential Absorption
OD Falls on the straight-line portion of the CC
Steep CC

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Tips for Low Contrast-Long Scale of Contrast

High Scatter Radiation
Low Differential Absorption
OD falls on the toe and shoulder
Shallow CC

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Kvp Vs. Density

Directly related to OD and IR expo but not proportional
↑ kVp, ↑xray quantity (kVp²)
↓kVp, ↓ xray quantity (kVp^5)

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high KVp chain [H.Ix.DdD.Is.L

high kVp→ increase xray beam pene → decreases DA → increase scatter → low contrast

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mAs vS Density

control quantity
directly prop to OD
↑ mAs, ↑ IR expo and film density

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SID vS Density

indirect
↑ SID, ↓ film density and IR expo
mAs must be increased

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OID vS Density

indirect
↑ OID, ↓ radiation, exposure, scatter, OD/IR

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Anatomical Part vs Density [TAXO]

↑ thickness, ↑ attenuation, ↓ xray quantity, ↓ OD/IR exposure (indi)

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lung [mass density]

320

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fat [mass density]

910

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soft tissue, muscle [mass density]

1000

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bone [mass density]

1850

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air cm [mass density]

1.3

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barium [mass density]

3500

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iodine [mass density]

4930

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calcium [mass density]

1550

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concrete [mass density]

2350

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molybdenum [mass density]

10, 200

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lead [mass density]

11, 350

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rhenium [mass density]

12,500

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tungstate [mass density]

Study These Flashcards

19, 300

increased pt thickness chain

↑ patient thickness → increases volume of tissue irradiated → increases scatter rad → low contrast

constructive pathology vs density [IDD)

increase attenuation decreases xray quantity decreases OD/IR exposure mAs must be increased

constructive pathology [3ACHMePPS]

Aortic Aneurysm Ascites Atelectasis Cirrhosis Hypertrophy Metastases Pleural Effusion Pneumonia Sclerosis

destructive pathology [2ABoCaDEOP]

active tuberculosis atrophy bowel obstruction cancer degenerative arthritis emphysema osteoporosis pneumothorax

positive cm vs density

radiopaque high atomic o. increase attenuation decreases x-ray quantity decreases OD/IR expo

fat [effective atomic no.]

6.3

soft tissue and lungs[effective atomic no.]

7.4

bone [effective atomic no.]

13.8

air [effective atomic no.]

7.6

iodine [effective atomic no.]

barium [effective atomic no.]

concrete [effective atomic no.]

molybdenum [effective atomic no.]

tungsten [effective atomic no.]

lead [effective atomic no.]

high atomic no. chain

high atomic number → positive cm →radiopaque → high contrast

dev't time vs density

increased development time, more silver ions are reduced to black metallic silver, increase OD decreased development time, fewer silver is reduced to black metallic silver, increases OD

increased developer, temp, replenishment rate chain

increased developer, temp, replenishment rate → increases chemical fog → shallow curve → low contrast →very high OD → OD on the shoulder portion → low contrast

decreased developer, temp, replenishment rate chain

decreased developer, temp, replenishment rate → very low OD → OD falls on toe portion →low contrast

screen speed vs density

large phosphor, greater no. of light produced per incident x-rays, increases OD/IR expo, mAs must be decreased

ultra high or hi plus [relative speed value]

300

high or fast screen [relative speed value]

200

medium, par or standard screen [relative speed value]

100

detail, slow or high resolution [relative speed value]

ultra-detail

Fast Screen chain

Fast screen

Fast Screen chain [SIDH]

Fast screen → steep curve → increases OD differences → high contrast

Slow Screen chain [S. S. D. L]

slow screen → shallow curve → decreases OD differences → low contrast

collimation vs density

increased collimation, decreases primary beam FS, decreases no. of photons available, decreases, scatter, decreases OD/IR expo, mAs must be increased

increased collimation chain

increased collimation chain → decrease FS → decrease tissue volume irrad → decrease scatter rad → high contrast

grid ratio vs density

high grid ratio, increases scatter rad clean up, decreases, scatter radiation, high contrast

filtration vs kVp

increased filtration → decreases low energy x-rays → increases beam hardening → decreases differential absorption → low contrast

screen film vs kVp vice versa for direct-expo film

screen film → steep curve → increases OD differences → high contrast

affects the number number of x-ray pulses and the total average photon energy

voltage ripple

High voltage ripple/ Hi Generator chain

high generator → low V ripple (<1%) →increases average energy → decreases differential absorption → increases scatter → low contrast

Part III Flashcards

(59 cards)