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93 Cards in this Set

  • Front
  • Back

Pyramid problem

Technical factor

Subject density


Film processing


Interrelationship of these factors can result in endless potential problems?

Pyramid Problem

Analytical Process

Diagnosing and treating image

Diagnostic Process

Narrowing search field

Hypostases activation

Information seeking

Hypothesis evaluation

Diagnosing process

Careful breakdown of whole into parts

4 parts

Goodness and greatness

Diagnostic process

Matter of attention to detail

Problem Solving

Diagnostic process

Analysis, Syntheses, evaluation

Narrowing the search field 1

Diagnostic process

Begin with overview

Note difference

Seek patterns within cues

Hypothesis Activation 2

Diagnostic process

Seek Hypotheses

Hold cues that do not fit hypothesis in reserve

Information Seeking 3

Diagnostic Process

*Questions to validate hypothesis

*Shift focus to all possible explanations when cues discovered

Hypothesis Evaluation 4

Diagnostic Process


*Must resolve most cues

*Predict solution

Diagnostic process improvement

1) Remember that cues are not diagnosis

2) Be careful to separate observations from inferences

3) Avoid jumping to conclusions at first cue

4) look for competing hypothesis

5) Try each cue with each hypothesis

6) Validate hypothesis w questioning when possible

7) Rule out each hypothesis one by one

8) Be Cautious of premature closure

9) Be tentative in diagnosis until experienced

10) Be confident in your expert knowledge- Important

Acceptable Limits

*Graphing acceptable limits

*Striving for perfection

*Factors affecting acceptance limit curves

*Practical considerations

Graphing acceptance Limits

*Fix limits of acceptable versus not acceptable radiographs

*Parties responsible for evaluation acceptance levels, rads, supervisors, radiologists, physicians

Striving for perfection

*Corrections should strive for perfect image not just acceptable

* Competency questioned when unable to correct repeated mistake.

Acceptance limit curves

Extremely narrow, high repeat rate

Wide acceptance limits

*may result in high repeat rates

*technologists can become careless

Narrow acceptance limits

*May result in production of near perfect

center radiographs

Ideal acceptance limits

Right in the middle, small but perfect image

Practical Considerations

*If repeat, make changes large enough to cause visible difference

*Be confident

Density IR/Exposure

*Comprise visibility of detail

*1 of 2 photographic properties, detail to eye


New term for density is called?

*IR exposure



monitor control function Light VS Dark

*not the same as density

Window level

Post processing, changes in Brightness

*Not the same as density

Brightness and Density

Are not interchangeable

Assessing Density/ IR exposure Film

*Assure proper densities present in anatomy of interest

*Keep room dark for the film, bright light can eliminate excess information

Film: OD= Optical density

Our range of seeing things B&W

Typical OD range .25-2.5

(Human Visibility range )

Assessing Density/ IR Exposure=Digital Systems


*Detail not recorded

*like polar bear in a snow storm, two few photons

Assessing Density/ IR Exposure=Digital Systems


*Digital post processing can eliminate excess info on overexposed

*Can save image like burnt toast

*Over better than under

Effects on Image Appearance

*Digital follow linear IR response curve

*for mistakes=Histogram kicks in

*Film follows D-Log-E Curve

* Toe=underexposed

* Shoulder= Overexposed

Min 30% difference for eyes to see

Factors affecting Density/ IR exposure

Density IR exposure

*Controlling MAS

*Influencing KVP

Other influencing factors,

-Focal spot -anode heel effect -distance -filtration -beam restriction-anatomic part( tissue type, thickness, CM, and pathology) -Grid Construction (ratio, frequency) -Image receptor ( digital, film)

Physical part of the image -Recorded detail

(Geometric properties)

What can effect detail


-Focal spot

-Distance (OID, SID)

*Image Receptor (Film Screen, Digital)

*Motion (Involuntary, voluntary, equipment)

Physical part of the image -Distortion

(Geometric properties)

What can effect detail


-OID and -SID (Centering ray, Part, IR)


-Alignment, angulation (Direction, Degree)

MAS Reciprocity Rule

*film Only

*Fails for extremely short exposure .01

(100ma x .1seconds= 10MAS) but if you need to up MA to 500 and keep 10 MAS

(500MA X .02seconds= 10MAS)

Same density different factors

Changes in mAS

*Changes made in doubles or halves

*Repeats, change 30% or higher go big or go home

*as mAS increases x-ray exposure increases proportionately

Changes in mAs 2

*f/s= a min of 30%

*Digital systems= 25%-30%

*use seldom, anytime changing MAS you are alternating the # of photons as MAS goes up so does density.


*Only changes in MAS

-Halves= Divide by 2

-Doubles= Double multiple by 2

*Beware of the plethora of changes possible


KV as an influencing factor1

*alters intensity in 2 ways (Strength of photons, controls ave energy of X-ray phones @anode target)

KV as an influencing factor 2

*Affects production of scatter

*Change in Kvp varies quantity & quality

*Increase scatter increase density, unwanted fog

*Increase KVP creates density but is the overall controlling factor for CONTRAST

(KVP) Small changes can have profound impact on density IR exposure

-15% increase= doubles exposure

-15% decrease= halves exposure

*4-5% in power kip ranges (30-50kvp)

*10-12% in higher range (90-130% KVP) Will effect visibility

* only use when density and contrast desired

Generator configuration

(we use only high frequency)

*Affects average energy of beam

-only consider when changing single to high-frequency multi-phase

-better to just change kip

1^2= HIGH FREQUENCY= times MAS by conversion factor of .5

High frequency= 1^2= times MAS by conversion factor of 2.0

Grid conversion factor

Mas X Conversion factor

ex: 10 MAS x 0.5= 10 MAS

Focal spot

(Only affects detail)

Large (1.5-2)

small (.5)

Anode Heel Effect

*alters intensity across cathode and anode axis

*Density= 45% greater at cathode side

*wide open collimator

*small anode angle inside machine (12 degrees or less) makes anode heel affect more pronounced with wide open collimator

Distance SID and OID


*Inverse square law (new exposure)

- I1/I2= (D2)sq (D1)sq

*Exposure maintenance (mas maintenance)


Distance SID and OID

Accuracy=only with moderate acceptance range impossible to predict with all factors of the imaging system

*Direct swear law directly proportional

Rough "Rule of thumb"

*Distance doubling and halving will bring IR exposure within roughly 50% OF THE ORIGINAL EXPOSURE



*Types= Inherent, added and total (2.5 mm al 70 KVP or higher)

*Inversely related to density

*Increase filtration Decrease density

Technique adjustments

*Large body parts

*High KVP

*Low Grid efficiency (Low grid ratio)

*non-grid (Extremities)

Anatomic part 1

-PT prime factor

-Thickness, tissue type average z#, tissue density CM

Anatomic 2

-Positive CM= increase atomic # and decrease density

-Negative CM= decreased atomic # and Increased density


-Additive radiopaque ( decreased Density)

- Negative radiolucent ( Increased density)

Part thickness variation with large tube angles

*every 10-15% angle adds thickness to 1 inch sid and Increases tissue thickness

*treat cast if thicker part


- Inversely related

- increase grid ratio decreases density

- More efficient a grid is less IR exposure less density will be recorded only improve contrast

Grid conversion factor


Image Receptor

-Exposure index number useful parameter for digital

-(EI and SI #s)

-Relative speed (RS#s)

-Useful parameter for film screen combinations


Film processing

-increases density

-increase developer temp (hot oven)

-increase immersion time (in oven to long burnt)

-increase replenishment rate of chemicals (to much chlorine)

- if these factors decrease so does density

Digital world

-Manufacturers set collaboration

-Uses algorithms to set histograms

-exposure indicates EI and SI #s

-Digital systems have much wider acceptance ranges (Fudge factors)

-Limits will be set on how much post processing techs can do in the future.


-Difference between adjacent densities

Assessing contrast

-2 photogenic effects allow detail to be seen

-allows us to see density and contrast

-digital range- digital image on a monitor window width- changes brightness and contrast

Assessing contrast 2

-Image contrast

- difference between adjacent densities

-Dynamic range

- range of brightness as displaced on screen

-difficult to separate the 2 change in density will affect contrast

-add or take away density inverse relationship, if density goes up contrast goes down

High contrast (Extremities)

- short scale


-Low Kvps

-short narrow dynamic range

- low frequency, low penetration

-increased contrast

Low contrast (Abdomens)



L=Low contrast

L= Long scale wide latitude

-long scale


-high kvp

-decreased contrast

-high frequency

-more penetration

Manipulating contrast

-Depending on desired contrast the densities are compressed or expanded into a range of visible densities (Achieved by:)

-Change in D log E curve film

- Adjustment to kvp

- Adjustment of window width -digital

Image contrast

-IS the total amount of contrast from

- IR= image receptor contrast

- Pts= patients anatomic part=subject contast

IR/ Film itself contrast

low contrast

-Film contrast= range of densities the film system is capable of recording

- D log E curve

*depends on 4 things

1) intensifying screens

2) film density

3) D log E curve

4) processing

Intensifying screens

high contrast

-Directly exposed film has LOW contrast than screen film (with an intensifying screen)

- Dramatic change in D log E curve when screen film directly exposed

Changes to contact FILM

-intensifying screens have higher contrast

(increase,short scale)

-the speed of the screen doesnt matter

-both excessive or inadequate density /IR exposure decrease contrast (all black or all white)

-Steeper the slope higher the contast

Changes to contrast DIGITAL

-window with manipulation

-pre set algorithms

-techs post process and histograms and LUT are used to standardize the data


-Differential absorption: for detector sensitivity to tissue differences

Subject contrast

-differences in intensity of beam after, it passes though pt (Attenation)

-Dependent upon= kip, amount of irradiated and type of material

KV and subject contrast

-kvp prime factor

-as kip increase (Wider range of photon energy)

- greater penetrability, wider greater range of exposure

- great amount of scatter Compton-long scale-contrast grays.

Amount of irradiated material

- dependent on thickness of part and field size

-Affects # of photons reaching the IR

- when the differences between adjacent body part thickness is great, subject contrast increases

Amount of irradiated material 2

Increase in thickness and field size

- increase scatter

- long scale of contrast

- Decrease subject is the result

Types of irradiated material

-influences by atomic # and tissue density (physical) how tightly packed the cells are

*high atomic # tissue density

- greater attenuation (bones, muscle)

-Large difference in atomic # and tissue density of adjacent tissues

- increase contrast

- CM= positive= higher contrast

- CM= negative= low contast

Evaluating contast

-good range of densities present

-anatomical structures intrest present

-satisfy diagnostic quality

-sufficient contrast and density

-knowledge of anatomy of physiology

- normal and abnormal

Random kip tis digital

-Dont exceed 80 kip for non grid

-PE increases as kip increases

Factors affecting contrast


-increased Kvp and decreased contrast more grays (Inversely related)

- controls scatter production (Direct relationship)

-MAS influences

Influencing factors


Focal spot size

anode heel effect

beam restriction, collimation pbl


f/s combos

anatomical part



Filtration OID


changes density, alters contrast

Focal spot size

nothing only detail duh

Anode heel effect

little to no effect

Beam restriction

collimation, PBR= direct effect


primary function is contrast improvement, it removes scatter

F/S combos

increase grid ratio increase contrast

- d log e curve

- steeper the slope greater the contrast


contrast improvement factor

k= ave gradient with grid

ave gradient without grid

-if k= 1 no improvement occurred

-most grids k= 1.5-3.5 times better contrast than non grid

Anatomical part

tissue type, thickness and pathology


SID= alters image receptor exposure

-can change contrast if change in mass

OID= air gap technique increases contrast


-altering the average photon energy of the beam, measured in mm of al eq

-Inversely related

**increased filtration

- increase average beam energy

- decreases contrast, creates more scatter as in Compton

Digital systems

-determined by histograms and LUT

- displayed as various bit depth values

- post processing effects contrast and visibility of detail

KVP negabile effect

increasing MAS

decreasing MAS

focal spot size

anode heel effect

increasing SID

decreasing SID

increasing F/S relative speed

decreasing F/S relative speed

KVP increasing contrast

-increasing OID

-decreasing filtration

-increasing beam restriction/collimation

-decreasing amounts of irradiated material

-increasing the differences between the atomic # and tissues

-decreasing density of tissue

-using CM increase or decrease atomic #

-destructive pathological condition

-increasing grid ratio

KVP decreasing contrast

-decreasing OID

-increasing filtration

-decreasing beam restriction/collimation

-increasing amount of irradiated tissue

-decreasing the differences between the atomic number of tissues

-increasing density of tissue

-additive pathological conditions

-decrease grid ratio

MAS negligible effect with density

-focal spot size

-anode heel effect

MAS increasing density

-Increasing KVP

-increasing number of pulses in the generator waveform

-decreasing distance

-decreasing filtration

-decreasing anatomical part

-decreasing beam restriction/ collimation

-decreasing grid ratio

-using radiolucent contrast media

-destructive pathological conditions

-increasing F/S combination relative speed

-increasing film processing developer time temp and replenishment rate

MAS decreasing density

-Decreasing KVP

-Decreasing number of pulses in the generator waveform

-increasing distance

-increasing beam restriction/collimation

-increasing anatomical part thickness or tissue type

-using radiopaque

-additive pathological conditions

-increasing grid ratio

-decreasing film screen combination relative speed

-decreasing film processing developer time temp and or replenishment rate