Patient as Beam Emitter

attenuation is a

reduction in the number of photons in the beam after Compton and photoelectric interactions

attenuation is dependent on

part thickness, tissue density, atomic number, beam energy

more matter has more

attenuation

denser areas (bone) will attenuate

more

different structures attenuate

differently

lower energy photons will penetrate less and

attenuate more

what are the four major substances account for variable attenuation as radiographic densities

gas, fat, muscle, bone

differential absorption is the

difference in how different materials absorb the photons in the beam

least absorbing power/more black on image

air

most absorbing power/less blackness on image

bone

bone shows up

white

muscles shows up as

gray

air shows up as

black

air

low tissue density, absorbs few photons, radiolucent

bone

composed of calcium and phosphorus salts, high absorption of photons, large precent of PE IX, results in radiopaque areas

the patient has an impact on properties affecting radiographic quality like

subject density, subject contrast, subject detail, subject distortion

subject density

refers to the impact the subject has on resulting IRE

increasing subject size decreases

IRE

subject contrast is the degree of

differential absorption resulting from the differing absorption characteristics of the tissues in the body

when there is little difference in absorption subject contrast will be

low

when there is a large difference in absorption subject contrast will be

high

subject contrast is dependent on the

tissue composition of a body part

subject detail

the spatial resolution of the structures is dependent on their position within the body and body’s placement in relation to the IR

more distance from IR means less

detail

pathology can alter the thickness and composition of a patient’s

tissue density

understanding pathology allows us to

adjust our technical factors accordingly

increased attenuation pathology diseases cause the body to

absorb more radiation and may require increase in technique

pagets disease

increased bone cell activity which increases bone density, common additive pathology

atelectasis

collapsed lung, common additive pathology

edema

common additive pathology

cardiomegaly

common additive pathology

CHF

common additive pathology

pleural effusions

common additive pathology

pneumonia

common additive pathology

ascites

common additive pathology

cirrhosis

common additive pathology

chronic osteomyelitis

common additive pathology

osteochondroma

common additive pathology

decreased attenuation pathology diseases absorb

less radiation and may require decrease in technique

atrophy

common destructive pathology

emaciation

common destructive pathology

emphysema

common destructive pathology

pneumothorax

common destructive pathology

bowel obstruction

common destructive pathology

active osteomyelitis

common destructive pathology

aseptic necrosis

common destructive pathology

degenerative arthritis

common destructive pathology

gout

common destructive pathology

osteoporosis

common destructive pathology