Intro to imaging

Question 1

radiographic timeline

Answer 1

-1885- x ray discovery by Wihelm Conrad Roentgen
-1940- 1/10 pts managed by radiographic study
-1950-1970- development of conventional angiography, nuclear medicine, U/S, and CT
-1980- almost all pts underwent some dx imaging
-1980s- MRI emerges
-1990s- molecular images
-new millennium- interventional radiography -> development of subspecialties based on organ system, specific fields -> genetic and molecular marker imaging

Question 2

X-Ray

Answer 2

-high energy photons, emitted by electrons generated by x-ray tube
-wire element one end (cathode) and metal target (copper, now tungsten) opposite end (anode)
-high energy electrons collide with metal target (anode) creating x-rays
-x-rays pass through pt to hit a specialized detector
-now its more digitalized

Question 3

pros of digital imaging

Answer 3

-Can be stored on CD/USB
-Permits remote access/telemedicine
-Can manipulate images
-Easy retrieval of previous studies/no lost films

Question 4

ionizing vs non ionizing studies

Question 5

radiation safety

Answer 5

-X-rays may cause damage to DNA molecules directly or produce free radicals that can chemically damage genetic material
-sievert = mSv or mrem -> measures radiation dosage

Question 6

radiation risk factors

Answer 6

-age (younger)- cells dividing and cumulative dose
-organ -> ovaries/eyes are sensitive
-heart/brain -> radiation resistant (more barriers)
-body region
-cumulative dose

Question 7

biological effects of radiation exposure

Answer 7

-Erythemia
-Skin peeling
-Ulcerations / skin lesions
-Cancers
-Cataracts

Question 8

short term effects of radiation exposure

Answer 8

-skin erythema -> starts to appear a few hours after exposure
-hematopoietic syndrome- damages bone marrow, leads to anemia, infections, bleeding, occurs after a whole body dose over
-1 gray (Gy) = 100 roentgen (Rads)
-one roentgen of x-rays may deposit anywhere from 0.01 to 0.04 Gy (1.0 to 4.0 rad) in bone depending on the beam energy
-doses of 200 to 1,000 rad delivered in a few hour will cause serious illness
-whole body doses of more than 1,000 rad are almost invariably fatal

Question 9

short term effects: GI syndrome

Answer 9

-destroys the cell that line the GI tract
-results in death due to inability to absorb nutrients and water
-occurs after a single whole body dose over 1000 rads (10Gy) for comparison 1 Gray (Gy) = 100 Roentgen (rads)

Question 10

short term effects: cerebrovascular syndrome

Answer 10

-destroys nervous system tissues and blood brain barrier
-occurs after a single whole body dose of 5000 rads (50 Gy)

Question 11

long term effects and primary concern of radiation workers in hospital settings

Answer 11

-cataract formation is deterministic and occurs at threshold of 100 rads
-vision impairment occurring at 500 rads
-skin effects can occur on hands of fluoroscopists who perform interventional procedures (SHIELDING IS ESSENTIAL)

Question 12

effects on fetus

Answer 12

-depends on stage of pregnancy
-pre-implantation period
-8-15 weeks increased risk of neurodevelopment (10-20 rad threshold)
-organ malformations can occur with exposures during major organogenesis
-increased incidence of early childhood cancer has been observed in children exposed in-utero

Question 13

issues concerning pregnant workers

Answer 13

-option of declaring yourself a pregnant worker NOT mandatory
-there is a declaration form
-fetal dosimeter in addition to standard dosimeter
-monthly exposure rate would be restricted to 50 mrem (.5 mSv) per month and 500mrem for pregnanct

Question 14

dosimetry

Answer 14

-radiation workers are given badges that will monitor an individuals exposure
-use of landauer OSL (optically stimulated luminescence) badges
-badges are made of aluminum oxide
-nuclear medicine workers are also given ring badges which contain LiF TLD’s (thermo luminescence dosimeters)

Question 15

ALARA princinples

Answer 15

-always wear personnel monitor
-radiology personnel should not restrain pts
-sound radiographic exposure factors
-cardinal rules of radiation protection: time, distance, shielding

Question 16

distance

Answer 16

6 feet of clearance

Question 17

shielding

Answer 17

-lead aprons can reduce exposure by as much as 95%
-thyroid shields and lead gloves are available for use in fluoroscopy
-when working with radioactive material, use lead blocks, syringe shields and lead pigs to reduce exposure

Question 18

scatter radiation

Answer 18

-protect- time, distance, shielding
-MC type of exposure you will receive in dx radiology

Question 19

safety guidlines

Answer 19

-justification- appropriate indication for imaging procedure
-optimization- ALARA (as low as reasonably achievable)
-limitation
-american college of radiology guidelines- systems to decrease the utilization of low yield CT scans

Question 20

target film distance (TFD)

Answer 20

-distance between tube and cassette
-Increased TFD produces clearer image
-3 feet ideal distance for chest X-rays

Question 21

object film distance (OFD)

Answer 21

-distance between the person and cassette
-Short as possible for most accurate image
-If increased will cause magnification
-decrease distance causes decrease magnification! (this is good)
-greater distance causes scatter

Question 22

golden rules

Answer 22

-Review previous tests to answer current questions.
-Select the appropriate study.
-Communicate/Consult with the radiologist & technicians!!!
-Only request studies that will influence management.
-Prepare patient to minimize delays in getting study done.
-Continually filter results in the context of the patient.
-Ensure appropriate follow-up
-Balance risks and benefits
-Provide patient-centered care: inform, consent, educate

Question 23

reasons for errors in radiology

Answer 23

-errors in interpretation
-failure to suggest next appropriate procedure
-failure to communicate results in timely and clinically appropriate manner

Question 24

radiology vs other medical specialities

Answer 24

-yields presumptive….….. but NEITHER a histological nor a biological diagnosis
-depends entirely on visual perception!

Question 25

5 x-ray densities

Answer 25

-black- air
-dark grey- fat
-grey- soft tissue
-light grey
-white- metal

Question 26

shadowgram

Answer 26

-attenuation- amount of radiation absorbed by tissues
-increased attenuation -> appears whiter
-more absorption of radiation by tissues
-less radiation reaches the cassette
-whiter areas -> opaque, opacified or radiodense

Question 27

decreased attenuation

Answer 27

-less radiation absorption by tissues
-Appear as DARKER (blacker) areas on radiograph.
-Different amounts of radiation escape from different tissues.
-More radiation reaches the cassette.
-“Non-Opaque” or “Radiolucent”: Terms describe darker areas on radiograph

Question 28

density

Answer 28

-dense parts do not allow photons to pass through -> White
-less dense tissue (muscle, fat, air) -> allow x-rays to pass through and hit photographic plate -> dark

Question 29

terms used for white

Answer 29

-x-ray- increased density, opaque
-CT- increased attenuation, hyperdense
-MRI- increased signal intensity
-ultrasound- increased echogenicity, sonodense, hyperechoic
-nuclear medicine- increased tracer uptake
-barium studies- radiopaque

-vice versa -> opposite of opaque is lucent

Question 30

pros and cons of x-ray

Answer 30

PROS:
-Fast
-Cheap
-Quick
-Easy to perform
-Detects calcium, bone, air, gas, metal
-Produces few artifacts
-less radiation
CON:
-Radiation exposure – can cause cumulative damage
-difficult to evaluate soft tissue – muscles, masses, blood, water, solid tumors
-Image variability – position/technique

Question 31

plain radiograph

Answer 31

-portable is usually AP -> ideal target film distance 3 ft
-affected by angle of x-ray beam and distance from x-ray source to object

Question 32

projection technique conventional x-ray

Answer 32

-shadowgram
-all structures in path of x-ray beam are superimposed upon each other
-requires multiple views to localize structures/objects
-most imaging involves at least 2 views often at 90 angles for better localization

Question 33

pt position

Answer 33

-supine
-upright
-lateral
-decubitus - place pt in left decubitus if youre looking for left lung fluid

Question 34

distortion

Answer 34

-Affected by
-Xray Source to Image receptor Distance (SID)
-Object to Image receptor Distance (OID)
-Angle of xray beam
-Motion
-Patient position/thickness

Question 35

source imaging distance (SID)

Answer 35

-if you increase SID while keeping object to image receptor distance the same -> x-rays from focal spot spread less after they pass the object on their way to the film
-increasing SID -> cuts down on blurring and improves recorded detail*

Question 36

motion (blur)

Answer 36

-types:
-involuntary motion- cardiac, peristalsis, spasm, tremor
-voluntary motion- pt moves
-equipment motion- bucky activation, portable x-ray tube lock failure, cassette movement

Question 37

key points

Answer 37

-select appropriate study
-test should provide information that will influence tx
-consult with radiologist or tech
-always review all radiographs you have ordered
-avoid “tunnel vision” and “satisfaction of search” when reviewing study
-always treat pt not the radiograph
-know anatomy

Question 38

shorter waves

Answer 38

more dangerous

Question 39

ionizing

Answer 39

-radiography
-CT
-nuclear scintography

Question 40

non ionizing

Answer 40

-MRI
-echocardiography
-ultrasound

Question 41

abdomen scan

Answer 41

water density
-abdominal organs have similar density and atomic weight
-harder to differentiate than chest

Question 42

what determines the amount of radiation absorbed

Answer 42

-atomic weight and
-tissue depth