Prior Instrumentation Exams

Front 1

When a charged particle interacts with an atom or molecule in such a way as to remove an electron completely from its orbit, this interaction is referred to as an:

Back 1

Ionization event

Front 2

Which region of the gas curve do ionization chambers operate in?

Back 2

Saturation region

Front 3

Radiation can be defined as:

Back 3

Emission of energy

Front 4

Which detector has the greatest sensitivity for detecting radiation?

Back 4

GM meter

Front 5

What are the QC measures for the dose calibrator and when should they be performed?

Back 5

Constancy - daily

Linearity - quarterly

Accuracy - annually

Geometry - installation/maintenance

Hint 5

There are 4: CLAG

Front 6

Detector efficiency equation

Back 6

CPM/DPM x 100

Front 7

Geometric efficiency equation

Back 7

(1/2)(1-cos°) x 100

Front 8

Which type of interaction is most desirable for Nuclear Medicine imaging purposes?

Back 8

Photoelectric absorption

Front 9

The percent full width at half max is often used as a measure of:

Back 9

Resolution

Front 10

Which detector provides a reading of the rate of radiation exposure?

Back 10

Ionization chamber

Front 11

Intrinsic efficiency can be defined as:

Back 11

The fraction of radiation striking the detector that interacts with it.

Front 12

In the GM meter, the size of the pulse is:

Back 12

Independent of the amount of energy deposited in the gas by the ionization event

Front 13

What is dead time?

Back 13

Time required to process an ionization event.

Front 14

True or false? We use pulse-height spectrometry to analyze background radiations, scatter radiation, and unknown. Nuclides.

Back 14

True

Front 15

There are several factors that cause spectral blurring when analyzing an "actual" spectrum. What are some?

Back 15

Counting rate

Summing events

Backscatter peaks

Imperfect energy resolution

Front 16

A detector that produces an electrical signal for an interaction, whose amplitude reflects the energy absorbed is said to have:

Back 16

Energy resolution

Front 17

Geometric efficiency of a detector depends on two things

Back 17

Position/configuration

Distance

Front 18

Ionization detectors require calibrations (blank) and are completed by the rad health Dept.

Back 18

Annually

Front 19

Due to cost and size restrictions, semiconductor detectors are not often part of the typical Nuclear Medicine clinic. In which setting would you be most likely find this type of detector?

Back 19

Intraoperative suite, cardiology clinic, Nuclear research facility, radiochemistry lab

Front 20

Which of the hint statements is not true of the dose calibrator

Back 20

Reports in mR/hr for the source

Hint 20

Used to measure the quantity of radioactive

Uses Argon gas as the detector media

Reports in mR/hr for the source

Can be used to calculate pre/post-calibration activity

Front 21

Energy linearity can be defined as

Back 21

The proportionality between output pulse amplitude and energy absorbed in the detector

Front 22

If an event occurs during the dead time of the preceding event the effect is ignored with no subsequent effects. This is known as a:

Back 22

Non paralyzable system

Front 23

When viewing a pulse-height spectrum for Tc-99m, we often see a weakened photopeak around 140 keV and a much larger photopeak around 511 keV, due to coincidence summing events.

Back 23

False

Hint 23

Summing events only happen with isotopes with more than one useful energy

Front 24

What is the approximate full width at half max?

Back 24

20 keV

Front 25

What is the energy resolution percentage equation?

Back 25

(Change in E / max photopeak) x 100

Front 26

The rate of emission per unit time is known as:

Back 26

Disintegrations per time (dp(t))

Front 27

Describe the methods used to perform the linearity quality control measure for the dose calibrator:

Back 27

Decay method - use a source of Tc-99m with 50-100 mCi. Plot and graph the activity level each day over a course of 8 days, along with the expected activity level and compare. Should be within 10%

Attenuation Method - use a source of Tc-99m with 50 mCi. Use different sizes sleeves of lead to mimic decay. Plot and graph the activity level vs expected level. Should be within 10%

Hint 27

2 methods

Front 28

Explain the ionization avalanche process for GM meters:

Back 28

An ionization event ejects a photon that causes another ionization event and so on.

Front 29

Because the well counter has nearly 100% geometric and intrinsic efficiencies, what is important to keep in mind when preparing the sample for counting?

Back 29

Sample volume/activity low

Front 30

3 components of absorption and scatter

Back 30

Nonuniform detection efficiency

Simultaneous detection emitted radiations

Attenuation and scatter of radiation outside detectors

Front 31

The exponential increase in number of electrons from cathode to anode occurs in the:

Back 31

PM Tube

Front 32

A lead bar phantom is used to determine:

Back 32

Spatial resolution

Front 33

Energy corrections are applied to the image...

Back 33

As scintillation events are acquired.

Front 34

Typically, an increase in resolution results in:

Back 34

A decrease in sensitivity

Front 35

Increasing the hole diameter of septa results in:

Back 35

Increased sensitivity

Front 36

The resolution of parallel hole collimators is best at:

Back 36

The collimator surface

Front 37

As a pinhole collimator is moved farther away from the thyroid, how will it affect the image?

Back 37

The gland will appear smaller

Front 38

In quantitating scintillation camera uniformity, the central field of view is defined as the diameter of the useful field of view times:

Back 38

0.75

Front 39

Static frame mode acquisition is the most appropriate type of image acquisition for which of the following procedures (in the hints)

Back 39

Thyroid imaging study

Hint 39

First phase of a 3 phase bone scan

Left ventricular ejection-fraction determination

Thyroid imaging study

Renal function imaging study

Front 40

If a 20% window is needed, what percentage should fall on each side of the centerline?

Back 40

10%

Front 41

Which of the following (hint) will increase the resolution of a "spot"-view bone image obtained with a parallel hole collimator?

Back 41

Moving the detector closer to the patient's body

Hint 41

Increasing the pulse-height analyzer window width

Using a high sensitivity collimator instead of a low energy all purpose collimator

Using a different gray scale to display the image with sharper contrast

Moving the detector closer to the patient's body

Front 42

Thallium is added to a sodium iodide crystal of a scintillation detector to allow the detector to:

Back 42

Enable the crystal to fluoresce at room temperature

Front 43

The best sensitivity of a low energy high resolution collimator is at which distance?

Back 43

Distance does not affect sensitivity

Front 44

For a 364 keV gamma ray, the best detection efficiency of a scintillation camera crystal is a (blank - in hints) thick crystal

Back 44

5/8 inch

Hint 44

1/4 inch

3/8 inch

1/2 inch

5/8 inch

Front 45

Spatial linearity correction is used on scintillation cameras to:

Back 45

Shift events to their correct location and improve flood uniformity

Front 46

Spatial resolution is defined as:

Back 46

FWHM mm

Front 47

Equation to determine dimensions of each pixel?

Back 47

Diameter of FoV/matrix size

Front 48

How to determine pixel coordinate location

Back 48

Convert given location to mm, divide by pixel size.

Front 49

Which of the following (hint) matrix sizes and acquisition modes would be most appropriate for a blood flow study if the feet?

Back 49

64 x 64 byte

Hint 49

64 x 64 byte

64 x 64 word

256 x 256 byte

256 x 256 word

Front 50

A technologist changes the collimator on a gamma camera from a LEAP collimator to a High-resolution collimator. If the same number of counts is acquired, how will the acquisition time change when the High-resolution collimator is used.

Back 50

The time will increase

Front 51

The image density for each pixel is determined by:

Back 51

The gamma ray counts stored within the pixel

Front 52

If a pixel can contain 1 byte of information, and if the counts per pixel reaches 256 counts, pixel rollover may occur and would result in:

Back 52

The pixel value returning to zero before resuming the count

Front 53

List the three corrections that take place within the scintillation camera.

Back 53

Energy

Nonlinearity

Nonuniformity

Front 54

List the four detection event types

Back 54

Valid

Object scatter

Detector scatter

Septal penetration

Front 55

True or false: intrinsic resolution worsens as gamma ray energy increases

Back 55

True

Front 56

Image contrast can be defined as.

Back 56

The ability to tell the difference between different objects

Front 57

What does quantum mottle refer to

Back 57

Noise

Front 58

Over time, PM Tube voltages tend to drift due to fluctuations in their high-voltage supply. Which Quality Assurance technique is applied to help maintain their performance?

Back 58

Gamma camera tuning

Front 59

Detection efficiency (blanks) as the thickness of the crystal increases.

Back 59

Increases

Front 60

The NaI(Tl) crystal material is hygroscopic. This refers to:

Back 60

It's ability to absorb moisture from the air.

Front 61

Contrast in an emission computed tomography image determines what?

Back 61

Whether two objects have different activity concentrations

Front 62

The 360° orbit is most often used in all of the following (hints) SPECT studies, except:

Back 62

Cardiac

Hint 62

Brain

Cardiac

Liver

Bone

Front 63

Body contouring or elliptical orbits in SPECT imaging have an advantage over circular orbit because they:

Back 63

Reduce the camera-to-patient distance

Front 64

DICOM does what?

Back 64

Allows for image transfer no matter the vendor or modality

Provides workflow management and communicates the status of procedures

Specifies standard formats for information such as: images, patients, studies, etc.

Front 65

Which attenuation correction method guaranteed an attenuation map?

Back 65

Transmission

Front 66

Ramp filtered projections are characterized by:

Back 66

Edge information enhancement

Front 67

OSEM reconstruction algorithms may be preferred over GBP because:

Back 67

OSEM is much faster

Front 68

A low pass filter does what?

Back 68

Allows low frequencies to pass and suppressed high higher ones

Front 69

In the reconstruction of SPECT images, segmentation refers to:

Back 69

Separating the organ from the bkg or nearby structures.

Front 70

Scatter correction methods can be applied at any time during the reconstruction process, true or false?

Back 70

False

Front 71

When the same nonuniformity is back-projected at each of the angles of acquisition, the result is:

Back 71

A ring artifact

Front 72

The center of rotation measurement determines what?

Back 72

Determines the offset between the camera and projections.

Front 73

Simple back projection results in:

Back 73

Blurring artifact

Front 74

Partial-volume effects are caused by:

Back 74

Tissue volumes that are smaller than the pixel/voxel size

Front 75

A correction technique for partial-volume effect is to apply a:

Back 75

Recovery coefficient

Front 76

When using iterative reconstruction techniques little post reconstructive filtering is required, true or false?

Back 76

True

Front 77

Spatial resolution, as a performance characteristic, is different in SPECT imaging than planar imaging in that:

Back 77

Both in-plane and axial resolution is reported

Front 78

PACS is utilized in imaging facilities to:

Back 78

Store images, view from any workstation, and transfer images among networks

Front 79

Without attenuation correction, myocardial perfusion studies in females may exhibit an artifact in the (blank) wall

Back 79

Anterior

Front 80

In a body area with uniform tissue attenuation which mathematical only attenuation correction technique may be applied:

Back 80

Chang

Front 81

For a 64 x 64 matrix, the COR value should be less than:

Back 81

0.5 pixel

Hint 81

Matrix is inversely proportional to pixel size

Front 82

Noise in frequency space is represented by:

Back 82

The highest frequencies

Front 83

Windowing in image processing, refers to the ability to

Back 83

Change gray or color scale to improve contrast

Front 84

The most common type of volume rendering is done with:

Back 84

Maximum intensity projection (MIP)

Front 85

In referring to attenuation correction, the probability of absorption increases as photon energy decreases. True or false

Back 85

True

Front 86

Scatter correction typically employs (blank) to correct errors due to Compton scatter.

Back 86

Dual energy window

Front 87

When metal artifacts are noted, it is best to perform reconstruction without using attenuation correction techniques..true or false

Back 87

True

Front 88

The sinogram is a:

Back 88

Common way to represent full projection data in the form of a 2-D matrix

Front 89

How to calculate ejection fraction:

Back 89

Normalize: (bkg cts x #object pixel)/bkg pixel

N/ED - ED = ED'

N/ES - ES = ES'

ED' - ES' / ED'