RADT 102 EXAM #3

Describe TOMOGRAPHY

isolates and visualizes a particular section of the body by blurring out structures above and below the area of interest

What is DRT

Digital Radiographic Tomosynthesis

• - less costly and less exposure than CT

• - stops and shoots or sweeps

• - 6-10 exposures at different angles = 1 single digital radiograph

What does CT do

produces transaxial or transverse images

What is the DESCRIPTION OF THE BEAM for the 1ST generation of CT

pencil beam

What is the DESCRIPTION OF THE BEAM for the 2ND / 3RD / 4TH generation of CT

fan-shaped beam

What is the NUMBER OF TUBES for the 1ST / 2ND / 3RD / 4TH generations of CT

1 tube

What is the NUMBER OF DETECTORS for the 1ST generation of CT

single detector

What is the NUMBER OF DETECTORS for the 2ND generation of CT

multiple detector assembly

• - 5-30 about

What is the NUMBER OF DETECTORS for the 3RD generation of CT

multiple detector array

What is the NUMBER OF DETECTORS for the 4TH generation of CT

multiple detector array

• - as many as 4000

What is the TYPE OF MOVEMENT for the 1ST generation of CT

Translate-Rotate

• - translates across pt, rotates between successive translations

What is the TYPE OF MOVEMENT for the 2ND generation of CT

Rotate-Translate

What is the TYPE OF MOVEMENT for the 3RD generation of CT

Rotate-Rotate

• - uses a curvilinear detector array

What is the TYPE OF MOVEMENT for the 4TH generation of CT

Rotate-Stationary

• - x-ray source rotates, but detector assembly does not

What is the IMAGING TIME for the 1ST generation of CT

5 minutes

What is the IMAGING TIME for the 2ND generation of CT

30 seconds

What is the IMAGING TIME for the 3RD generation of CT

subsecond imaging time

• - less than 100 ms

What is the IMAGING TIME for the 4TH generation of CT

subsecond imaging time

What are the ADVANTAGES of the 1ST generation of CT

finely collimated x-ray beam, which reduces scatter radiation

What are the ADVANTAGES of the 2ND generation of CT

speed was better than 1st generation (getting faster)

What are the ADVANTAGES of the 3RD generation of CT

a constant source-to-detector path length, which is good for image reconstruction

covers entire patient

better x-ray beam collimation, reducing scatter radiation

faster than 2nd generation

What are the ADVANTAGES of the 4TH generation of CT

allows each detector to be calibrated and its signal normalized for each image

very fast

free of ring artifacts

What are the LIMITATIONS of the 1ST generation of CT

too slow

What are the LIMITATIONS of the 2ND generation of CT

fan beam increases radiation intensity

too slow

What are the LIMITATIONS of the 3RD generation of CT

occasional appearance of ring artifacts

• - caused by malfunctions of the acquired signal or lack thereof

What are the LIMITATIONS of the 4TH generation of CT

does not result in constant beam path from the source to all detectors

increases scatter radiation

What does TRANSLATION mean (CT)

sweep around, cuts

• - tube rotates around the body

What does ROTATION mean (CT)

tube moving around

What does STEP AND SHOOT mean (CT)

pt couch moves in little by little to be shot, it stops to be shot at different sections

• - process allows you to catch the tail end of what you already radiated

What does MULTISLICE HELICAL mean (CT)

pt couch moves through as the tube is going around, doesn’t stop to shoot, keeps going

Describe CT OPERATING CONSOLES

• - dual monitors

• - operator turns CT scanner on and off

• - selects and control the protocol which is predetermined (including kVp, mAs, pitch, FOV, slice thickness, table indexing, reconstruction, algorithms and display windows)

• - kVp and mAs preselected along with focal spot size

Describe the COLLIMATION of a CT SCANNER

two collimators

• - prepatient

  • - determines DOSE PROFILE and PATIENT DOSE

• - predetector

  • - determines SENSITIVITY PROFILE and SLICE THICKNESS

Describe MRI

• - MAGNETIZES the atomic nuclei in hydrogen atoms

• - bombards these atoms with radiofrequency waves (generated by coil specific to the anatomy)

• - the coils shoot out RF waves, knock hydrogen atoms down and when they come back up they release energy that is sent back to coil, that information is digitized for image

• - hydrogen atoms absorb RF and re-emit back as radiowaves

• - signals are sent to computer to construct an image

• - magnetic energy is non-ionizing, MRI is non-ionizing

What does MRI demonstrate

soft tissue anatomy

What are the CONTRAINDICATIONS for MRI

metal in body or claustrophobia

List the ORDER of the CT NUMBERS for various tissues (GREATEST → LEAST)

• dense bone (3000)

• muscle (50)

• white matter (45)

• gray matter (40)

• blood (20)

• cerebrospinal fluid (15)

• water (0)

• fat (-100)

• lungs (-200)

• air (-1000)

As the tissue gets more DENSE, the CT number _____

INCREASES

What is the purpose of the ALGORITHM (AI)

• receive data

  • take in data that is labeled / unlabeled

• learn from data

  • analyze data to identify patterns / correlations

• make decisions

• adapt

  • improve over time as they are exposed to new data

What is ANI (AI)

Artificial Narrow Intelligence

• aka weak AI

• designed to solve a single task or narrow range of tasks

• goal-oriented and operates within predefined parameters

• lacks human-like intelligence and common sense reasoning

• e.g. voice assistants, recommendation engines, and image / speech recognition

What is AGI (AI)

Artificial General Intelligence

• aka strong AI / human-level AI

• aims to mimic human cognitive abilities

• can solve complex problems in settings and contexts that were not taught to it

• can learn from minimal data and adapt to new situations

• e.g. customer service, healthcare, autonomous systems

What is ASI (AI)

Artificial Superintelligence

• hypothetical AI system that surpasses human intelligence in every field

• would have advanced cognitive functions and problem-solving skills

What is SUPERVISED machine learning (AI)

uses labeled datasets to train algorithms to predict outcomes and recognize patterns

• given LABELED training to learn the relationship between the INPUT / OUTPUTS

What is UNSUPERVISED machine learning (AI)

learns from data without human supervision

• learning models are given UNLABELED data and allowed to discover patterns and insights without any explicit guidance / instruction

What is DEEP LEARNING (DL) machine learning (AI)

uses multilayered neural networks to simulate the complex decision-making power of the human brain

• subset of machine learning

List the possible APPLICATIONS of AI in IMAGING

• order scheduling and patient screening

• exam protocoling

• image acquisition

• image analysis

  • automated detection of findings

  • automated interpretation of findings

• automated clinical decision support (CDS)

• image post-processing

• determine what is STAT, needing TRIAGE

• can identify appropriate imaging exams based on findings

What is the difference between QA and QC

Quality assurance = about the PATIENTS

Quality control = about the MACHINE

Describe QA (quality assurance)

• responsibilities of managers and radiologists

• pt scheduling

• reception

• preparations

• safety

• personal treatment

• the team determines patient waiting time, patient education, and appropriate follow-up

What do RADIOLOGISTS do?

image interpretation

• disease/condition should be consistent with diagnosis

• outcome analysis (study that examines image interpretation process) required if diagnosis is not consistent

List the Joint Commission’s 10-step QUALITY ASSURANCE PROGRAM

1. Assign responsibility

2. delineate scope of care

3. identify aspects of care

4. identify outcomes that affect the aspects of care

5. establish limits of the scope of assessment

6. collect and organize data

7. evaluate care when outcomes are reached

8. take action to improve care

9. assess and document actions

10. communicate information to organization-wide quality assurance

Describe QC (quality control)

• monitors x-ray equipment

• ensures optimal image for radiologist

• medical physicists designs, implements and maintains

An acceptable QC program consists of what THREE steps?

• acceptance testing

  • when new equipment is given, it goes through testing to make sure it meets table criteria

• routine performance monitoring

  • done for machines to make sure everything still works (like taking a car to get oil changed)

• maintenance

  • something is broken/off and needs to be fixed

EVALUATION should follow any major equipment modification

true

What is the FREQUENCY / TOLERANCE of FILTRATION (table criteria)

• annually

• within 2.5 mm Al tolerance (greater than or equal to)

What is the FREQUENCY / TOLERANCE of COLLIMATION (table criteria)

• semiannually

• within 2% SID tolerance

What is the FREQUENCY / TOLERANCE of FOCAL SPOT SIZE (table criteria)

• annually

• within 50% tolerance

What is the FREQUENCY / TOLERANCE of CALIBRATION OF KVP (table criteria)

• annually

• within 10%

What is the FREQUENCY / TOLERANCE of EXPOSURE TIMER ACCURACY (table criteria)

• annually

• when GREATER than 10 ms, within 5%

• when LESS THAN OR EQUAL TO 10 ms, within 20%

What is the FREQUENCY / TOLERANCE of EXPOSURE LINEARITY (table criteria)

• annually

• within 10%

What is the FREQUENCY / TOLERANCE of EXPOSURE REPRODUCIBILITY (table criteria)

• annually

• within 5%

What TOOL is used to test FILTRATION

half value layer tool (HVL)

What TOOL is used to test COLLIMATION

• beam alignment test tool

• collimator test tool

• eight-penny (nine-penny if one put in center) test

Describe the EIGHT PENNY test (done for collimation)

• works at 72 INCHES

• field open 14 × 17, light field visualized

• one penny on outside of light, one penny on inside on all 4 sides

• when exposed, you should only see 4 pennies

• if you don’t see inside penny, that’s 2% error of collimation

• if you don’t see outside penny, that’s 1% error of collimation

What TOOLS are used to test SID

tape measure

What TOOLS are used to test FOCAL SPOT SIZE

• measurement focal spot

• pinhole camera tool (DIFFICULT, excessive exposure time)

• star pattern tool (EASY)

• slit camera tool (PREFERENCE)

What TOOLS are used to test KVP

• filtered ion chambers

• filtered photodiode

• voltage diode

• oscilloscope

• Wisconsin test cassette

• ardan and crooks cassette

• digital KVP meter

What TOOLS are used to test EXPOSURE TIMER ACCURACY

• ion chamber / photodiode assembly

• synchronous spinning top (MORE COMMON)

Describe the SYNCHRONOUS SPINNING TOP test (used for exposure timer accuracy)

• produces an image that is testing the specific time you want to test

• image looks like an arc, which is measured

• MATH EQUATION →

  • actual exposure time = arc size/360

What TOOLS are used to test for EXPOSURE LINEARITY

• SAME MAS, DIFFERENT mA, DIFFERENT time

  • uses precision radiation dosimeter (measures radiation intensity at various combinations of Ma / time that all equal the same MAS)

  • they should show the same read on the dosimeter, if not, mA station is off

• SAME time, DIFFERENT mA, DIFFERENT MAS

  • exposure should be INCREASING, but not by too much

  • between two adjacent stations it should only increase 10%

What TOOLS are used to test for EXPOSURE REPRODUCIBILITY

• precision radiation dosimeter utilized

• after an exam is done, technique is changed and a different exam happens

• then the same original exam is done again

• the image should be the same (reproducible) by 5% and shouldn’t deviate by much

What TOOLS are used to test for PROTECTIVE APPAREL CHECKING

• the shields are fluoroed annually for defects

• if there are cracks, tears, or holes the shield has to be discarded

How many RECTIFIERS in a 3 phase 6 pulse

6 rectifiers

How many PULSES PER SECOND in 3 phase 6 pulse

360 voltage pulses

How many PULSES PER SECOND in 3 phase 12 pulse

720 voltage pulses

How many RECTIFIERS in 3 phase 12 pulse

12 rectifiers

In a HIGH FREQUENCY system, the source of AC is fed into a _______ before entering the voltage section. This component changes the frequency of the AC from 60 hz to ________ hz

MICROPROCESSOR CIRCUIT

as much as 100,000 hz

What is the DIFFERENCE in the POWER RATINGS of a three phase / high frequency and single phase unit

single phase equation multiplies 0.707 also

• due to single phase rippling effect, AC requires the multiplier to be added

• three phase / high frequency equation =

  • KW = kVp x mA / 1000

• single phase equation =

  • KW = kVp x mA x 0.707 / 1000

The FLOOR of the control booth must not have an area LESS THAN _____

7.5 sq ft

The WALL of the control booth must be at least ________ and fixed to the floor

7 ft high

• must be shielded at least 1.5 mm

The WINDOW of the control booth must be _______ in size and mounted at least ________ above the floor

1 sq ft

5 ft

• must be shielded at least 1.5 mm

The DOOR of the examination room must _________

be interlocked with the control panel so that an exposure cannot be made unless the door is closed

The EXPOSURE SWITCH should be __________ from any open edge / open area

at least 30 inches away

The SCATTERING INTENSITY OF PHOTONS ________

must scatter at least twice before they can enter any opening in the control booth

• each time a photon scatters, its intensity from the scattering object is 1/1000 of the original intensity at a distance of 1 m

What is the appropriate LEAKAGE AMOUNT

1 mGya : 1 meter : 1 hour

What is used to test the MONITOR

SMPTE

AAPMTG-18

What are LUMINANCE PATCHES used for

looking for gross deviation in luminance adjustments

What is GRAY SCALE DISPLAY FUNCTION

maintaining consistent grayscale appearance on DICOM compatible display

What TOOLS are used to test LUMINANCE (?)

• magnifying glass

• photometer

What is LUMINANCE

brightness coming through

• measure of the brightness of a digital display device

• can be measured by photometer

What is ILLUMINANCE

light around the room, glare against the monitor

• measure of intensity of light incident on a surface

What is CQI / TQM

Continuous Quality Improvement / Total Quality Management

• focuses on the process vs the individual

• e.g. are undiagnostic images being sent to PACS … if the system goes down for any reason, how long is down?

What do SMPTE / AAOMTG-18 test for

• general appearance

• geometric distortion

• luminance, reflection, noise and glare

• tested monthly or quarterly

Describe testing for LUMINANCE

• looking for how bright the monitor is

  • 100 candeliter (cd/m)² per sq

• uses photometer

• 16 different luminance regions should be visualized

• checks for uniformity

Describe testing for RESOLUTION

• tools are magnifying glass and TG 18 QC pattern

• checking line pair patterns

What is REJECT ANALYSIS

checking the rejected images and why they were rejected

What is HEALTH PHYSICS

concerned with providing occupational radiation protection and minimizing radiation dose to the public

What does mGya MEASURE

the INTENSITY of the x-ray beam (milligray in air)

What is NCRP

National Council Radiation Protection

• makes sure there are numbers maintained that protect safety

What is ALARA

As Low As Reasonably Achievable

What is LNT

Linear Non Threshold

• x = exposure, y = effect

• any exposure past 0 is dangerous to pt, there is no safe exposure amount

• believes that anything past 0 gives an effect

• linear because effect is proportional to exposure

  • the higher the exposure, the more the effect

As you INCREASE QUANTITY, INTENSITY (mGya) ______

INCREASES

• direct relationship