Ct Registry Review 1

Front 1

Which generation scanner has Fan beam geometry and a detector array arranged in a curved arc?

Back 1

3rd Generation Scanner.

Front 2

The abdominal aorta bifurcates at what level?

Back 2

L4

Front 3

What is a normal platelet count?

Back 3

150,000-400,000/mm3

Front 4

Quantitative CT is used to measure what?

Back 4

The mineral content of bone.

Front 5

What is the average osmolality of high osmolar contrast?

Back 5

1000-2400 mOsm/kg water

Front 6

What is the density of a mass of fat cells in HU numbers?

Back 6

-50 to -100 HU

Front 7

A CT of the abdomen should be done during what kind of breathing?

Back 7

Full expiration. (Holding breath)

Front 8

What can be given to reduce peristalsis and distend the colon for a CT of the abdomen pelvis?

Back 8

Glucagon ( 1 mg. by I.V.)

Front 9

What is the term used to describe a radio density similar to that of another or adjacent tissue?

Back 9

Isodense. (Hemangiomas enhance from periphery in word until they become isodense.)

Front 10

Common areas of calcifications within the brain?

Back 10

Choroid Plexus and Pineal gland.

Front 11

Angle of the gantry during a CT of the brain?

Back 11

15° above orbitomeatal line

Front 12

What happens when you increase the average photon energy of a heterogeneous x-ray beam?

Back 12

Beam Hardening.

Front 13

Increased aperture size (slice thickness) will increase what?

Back 13

Signal to noise ratio.

Hint 13

Pixel x Matrix size= DFOV

Front 14

Calculate DFOV with a 320 Matrix and pixel dimension of 0.75x0.75 mm.

Back 14

0.75mmx320= 240 mm (24cm)

Front 15

The full width at half - maximum of the CT scanner describes?

Back 15

Spatial resolution.

Front 16

The average photon energy of the primary beam of a CT scanner with the tube potential of 120 KVP.

Back 16

70 KeV (average photon energy is 30-40% of applied kilo volts)

Front 17

How to reduce streak artifacts from edge gradient effect?

Back 17

Increase filtration, increase KVP

Front 18

What is statistical noise? (Static)

Back 18

Quantum mottle\graininess.

Front 19

Causes of low contrast resolution on scanner and the result to the patient?

Back 19

Increased electronic noise and decreased patient dose.

Front 20

The value of a pixel in H.U. Is calculated by?

Back 20

Comparison of linear attenuation. Coefficient of a voxel of tissue to that of water.

Front 21

Explain what contrast resolution is?

Back 21

The ability of scanner to differentiate objects with minimal differences in attenuation coefficients.

Front 22

What does dynamic scanning involve?

Back 22

Bolus of IV contrast, rapid scanning with minimal interscan delays.

Front 23

How will an acute subdural hematoma appear on a scan?

Back 23

Hyperdense.

Front 24

Benign pulmonary nodules will have a CT H.U. # of?

Back 24

+164 H.U.

Front 25

What area of the brain is not enhanced on the CT scan ?

Back 25

Posterior horn of the lateral ventricle. (Because it contains spinal fluid)

Front 26

What is interpolation used for?

Back 26

Mathematical technique used in reconstruction process of a spiral CT.

Front 27

A CT produces diagnostic images with improved_____?

Back 27

contrast resolution.

Front 28

What is the primary interaction between x-ray photons and tissue?

Back 28

Compton.

Front 29

Parental injection of medicine into the body? Name the different routes. (4)

Back 29

Intramuscular, intravenous, intradermal, subcutaneous.

Front 30

What is osmolality?

Back 30

The number of particles\ions formed when a substance dissociates in a given solution.

Front 31

The term used to describe systemic hypertension often leading to cerebral ischemia?

Back 31

Vasovagal.

Front 32

The interaction between x-ray beam and matter? (Also has the largest amount of patient dose.)

Back 32

Photoelectric effect.

Front 33

A common and effective sedative for children?

Back 33

Choral Hydrate.

Front 34

The portion of the nephron (kidney) that filters on wanted substances from blood plasma?

Back 34

Renal glomerulus.

Front 35

The adult spinal cord and at what level?

Back 35

L1-L2

Front 36

Body part that stores most of the mature sperm?

Back 36

Vas deferns.

Front 37

Which sinuses are absent at birth and do not fully develope until after puberty?

Back 37

Frontal sinus.

Front 38

A condition of excess nitrogenous material in blood?

Back 38

Axotemia, uremia.

Front 39

Partial voluming average can be decreased by________?

Back 39

Decreasing slice thickness.

Front 40

The artifact that occurs when the patient suspends respiration at different depths during scanning?

Back 40

Misregistration.

Front 41

Most common type of noise found in CT image?

Back 41

Statistical noise.

Front 42

CT window controls _______on the CT image?

Back 42

Contrast and brightness.

Front 43

What is the relationship between the CT number and actual linear attenuation coefficients of an object?

Back 43

Linearity.

Front 44

What is responsible for the math calculations of the image reconstruction process?

Back 44

Array Processor.

Front 45

What would decrease noise on a CT image?

Back 45

Decreasing the matrix size.

Front 46

What is the CT number for blood?

Back 46

+42 - +58 H.U.

Front 47

The math technique used exclusively for image reconstruction with spiral CT?

Back 47

Interpolation.

Front 48

A contrast material that may be described as one that does not dissociate into charged particles in a solution?

Back 48

Non-ionic contrast.

Front 49

What are the advantages of auto power injectors over manual bolus of contrast injection?

Back 49

Increased tissue enhancement due to faster injection time. And uniform administration over entire length of the scan.

Front 50

The third ventricle of the brain communicates with the fourth ventricle through the________?

Back 50

Cerebral Aqueduct.

Front 51

To differentiate between the duodenum and the head of the Pancrease what is the best way to scan. And what type of contrast to use, and timing of?

Back 51

Use oral contrast 30 to 45 minutes before the scan. It is best if patient is placed in right lateral decubitus while scanning.

Front 52

What is a glioma and where would it be found?

Back 52

It is found in the brain. It is a general term to describe a group of primary tumor's consisting of malignant glial cells.

Front 53

Does decreasing the matrix size decrease the noise on a CT image?

Back 53

Yes !!!

Front 54

Increasing the pitch during a spiral CT exam adversely affects the _______along with which axis?

Back 54

The spatial resolution. The Z axis.

Front 55

Pre-patient collimation directly controls________?

Back 55

Slice thickness.

Front 56

What reduces scatter radiation from reaching the detectors?

Back 56

Post patient collimation and pre-detector collimation.

Front 57

Name a type of iso-osmolar contrast media?

Back 57

Iodixanal (Visipaque)

Front 58

What are three types of non-ionic contrast media (low osmolar)?

Back 58

(Omnipaque 350) Iohexol

(Isovue 370) Lopamidol

(Visipaque 320) Iodixanol

(Ultravist 370) Iopromide

(Oxilan 350) Ioxilan

Front 59

Name two types of high osmolar contrast media?

(Ionic contrast)

Back 59

(Hypaque 50) Diatrizoate

(Isopaque 370) Metrizoate

(Hexabrix) Ioxaglate

(Conray)

Front 60

Explain, what is window width?

Back 60

Ranges of shades of gray on CT image. It is controlled by contrast.

Front 61

Explain what window level is?

Back 61

It's the H.U. at the center of window width. It controls density or brightness of the image.

Front 62

What is photon fluence?

Back 62

The quantity of x-ray photons passing through a specific area.

Front 63

What is photon flux?

Back 63

The rate at which the quantity of x-ray photons (fluence) passes through a unit area over time.

Front 64

What is Aliasing?

Back 64

A streaking artifact caused by insufficient number of views (data samples) obtained during data acquisition.

Front 65

Low energy photons are absorbed as x-ray beam passes through an object resulting in an increase of the average photon energy of the beam. This is called_________?

Back 65

Beam Hardening.

Front 66

What is binning?

Back 66

Electronically combining signal from adjacent detector elements to produce reconstructed CT image that is thicker than the detector width.

Front 67

What streak artifact occurs at the interface between a high density object and a lower attenuation material surrounding it?

Back 67

Edge gradient.

Front 68

What is M I P?

Back 68

Maximum intensity Projection. (Multiplanar Reformation) Displays maximum pixel value along Ray traced through viewer.

Front 69

Define temporal resolution?

Back 69

Ability of CT to freeze motion and provide blur free images.

Front 70

What is linear attenuation coefficient?

Back 70

Is a constant that describes the rate of energy loss by a photon beam per cm. within a medium.

Front 71

Describe what a step artifact is?

Back 71

In multiplane or or 3-D reformats the stair step artifacts produces loss of sharpness and loss of detail. Misalignment of the tube can cause these artifacts.

Front 72

Explain hyper dense?

Back 72

Attenuation values are greater than the surrounding tissues.

Front 73

Explain Hypo dense?

Back 73

Attenuation values are less than the values of the surrounding tissues

Front 74

What is iso-dense?

Back 74

The attenuation values are equal to the values of the surrounding tissues.

Front 75

What is iso-tropic?

Back 75

Equal dimensions along the X, Y, and Z axis.

Front 76

What is insufflation?

Back 76

The introduction of air into an organ or cavity for distention and improving visualization.

Front 77

Describe volume rendering?

Back 77

Is a set of techniques used to display a 2D projection of a 3D discretely sampled data set.

Adjusting opacity of Voxel's according to tissue type.

Front 78

What is convolution?

Back 78

Mathematical Filtration used by CT to remove blurring artifacts during back projection method of image reconstruction.

Front 79

Define what a kernel is?

Back 79

Mathematical filter applied to Raw data to remove the "blurring" artifact. A.k.a. algorithm.

Front 80

What is retrospective reconstruction?

Back 80

Reconstruction done after the initial re-cons are done. Using raw data to change DFOV, image center, etc.....

Front 81

What is considered the normal range for cerebral blood flow through the brain?

Back 81

50-60 ml./100g. Brain tissue/minute.

Front 82

What is considered a normal range of cerebral blood volume/100g. Of brain tissue?

Back 82

4-5 ml./100g. Brain tissue

Front 83

What is cerebral perfusion?

Back 83

The level of blood flow throughout the brain tissue.

Front 84

Define data acquisition system.(DAS) ?

Back 84

It is responsible for measuring the transmitted x-radiation absorbed by the detectors.

Front 85

The component of the CT system that receives raw data, performs all major re-cons and returns the recon images to storage memory to the host computer?

Back 85

Array processor.

Front 86

What are 10 organs that make up the retroperitoneum?

Back 86

Duodenum, pancreas, prostate, uterus, kidneys, ureter's, bladder, aorta, IVC, adrenal gland's.

Front 87

What is a normal BUN level (Blood Urea Nitrogen) and a normal creatinine level for adults?

Back 87

BUN: 7-25 mg/dl.

Creatinine: 0.5-1.5 mg/dl.

Front 88

What is a normal PT? (Prothrombin Time)

Back 88

12-15 sec.

Front 89

What is a normal PTT ?

(Partial Thromboplastin Time)

Back 89

25-35 sec.

Front 90

What is the normal range for a platelet count?

Back 90

140,000-440,000

Front 91

What is the parameter that is responsible for partial volume averaging?

Back 91

Slice Thickness.

Front 92

What is a single 2-D picture element within the image plane?

Back 92

Pixel.

Front 93

Define spatial resolution?

Back 93

The ability of CT to display fine details. (Units: line pairs/cm.)

Small detector size, small pixel, thin slice, small focal spot. *To get better spatial resolution.

Front 94

What is partial volume artifact?

Back 94

The error occurs when structure only partly positioned within the voxel and attenuation is not accurately represented.

Front 95

What is partial volume effect/averaging?

Back 95

Distortion in signal intensity from object because it partially extends into the Adjacent slice thickness. Inaccuracy in pixel values.

Values will average together to attempt to yield a single pixel value.

Front 96

What are the main components of a typical CT scanner and the path they are used starting with the console.

Back 96

Back (Definition)

Front 97

What year was the first CT scanner introduced for general clinical use?

Back 97

1973

Front 98

What type of scanner Incorporated an x-ray tube which generated a thin focused x-ray beam called a pencil beam through the patient to a single detector? Both the tube and the detector were part of an Assembly which moved or translated across the gantry while the patient remained stationary between them.

Back 98

First-generation scanners.

Front 99

What was the total scan time per image for a first generation scanner?

Back 99

5 minutes

Front 100

The tube and detector assembly moved across the patient then rotated by 1°. Which generation scanner is this?

Back 100

First generation scanner.

Front 101

What type of scanner had a "pencil beam" and a single detector?

Back 101

First generation scanner.

Front 102

Which generation scanner used a series of translate -rotate procedures covering an arc of 180° around the patient?

Back 102

First generation scanner.

Front 103

Which generation scanner incorporated and x-ray tube which generated an x-ray beam that had a shape similar to an open paper fan?

Back 103

Second generation scanner.

Front 104

Which type of scanner had a fan beam geometry and a group of detectors referred to as a detector array?

Back 104

Second generation scanner.

Front 105

About how many detectors were used in the second-generation scanners?

Back 105

30

Front 106

Which type of scanner utilize the tube/detector assembly moving across the patient and then rotating by 5°? Multiple detectors in a straight line.

Back 106

Second-generation scanner.

Front 107

What was the total scan time per image for second-generation scanners?

Back 107

20 seconds

Front 108

What were the two most important additions to the second-generation scanners?

Back 108

The fan beam geometry and introduction of the detector array.

Front 109

When were the third generation scanners first introduced?

Back 109

1975

Front 110

Which generation scanner has Fan beam geometry and a detector array arranged in a curved arc?

Back 110

3rd Generation Scanner.

Front 111

What is the scan time for the third generation scanners?

Back 111

Less than 1 second per image.

Front 112

Most scanners today are based off of which generation scanner?

Back 112

3rd Generation Scanner

Front 113

What is the primary difference between the third and fourth generation scanners relating to the detectors?

Back 113

In the fourth generation scanners the detectors do not travel with the tube they form a complete circle around the gantry in a ring configuration.

Front 114

With a continuous rotation scanner what piece of equipment is used to supply electrical power, accept scanning instructions, convey information concerning the measured attenuation data from the patient to the computer and array processor to facilitate image construction?

Back 114

The slip ring.

Front 115

In what year was the multi-row detector scanners offered?

Back 115

1998

Front 116

What type of scanner collects information from multiple anatomical slices in each rotation of the x-ray tube?

Back 116

Multi-row detector scanners.

Front 117

What are some benefits of the multi-row detector CT?

Back 117

Faster scans, increased anatomical coverage, and scanning with thinner slices to improve resolution along the slice direction.

Front 118

What type of CT is used for oncology?

Back 118

Cone beam CT

Front 119

What is the primary link between the technologist and the other components of the imaging system?

Back 119

The Host Computer.

Front 120

The axis which extends along the patient table or the long axis of the body is called what?

Back 120

Z axis.

Front 121

If the patient is lying supine on the table, the axis that extends from the patients left to right sided is called what?

Back 121

X axis.

Front 122

The axis that extends anterior to posterior through the patient is called?

Back 122

Y axis.

Front 123

An atomic particle with a negative electrical charge is called?

Back 123

Electron.

Front 124

When an electron collides with the nucleus of an Atom or enters the vicinity of the nucleus what happens to the electrons?

Back 124

They lose energy in the form of x-ray photons.

Front 125

Electrons losing their energy and slowing down forming x-ray photons is a phenomenon called what?

Back 125

Bremsstrahlung or braking radiation.