Digital fluoroscopy

Question 1

____ is the smallest element of a digital image

Answer 1

pixels

Question 2

_____ image is usually composed of a two dimensional matrix of pixels

Answer 2

digital image

Question 3

____ = the number of pixels in each row and column of the image

Answer 3

Matrix size

Question 4

relating to the matrix how is the image size more faithfully reproduced >

Answer 4

as matrix size increases and pixel size decreases

Question 5

Digital fluoro operates in ___ mode ???

Answer 5

radiographic mode

Greater than 100 mA

Question 6

Standard fluoro operates in ___ mode

Answer 6

fluoro mode

Less than 5 mA

Question 7

____ is the pulsed beam method utilized in digital fluoro to keep pt. dose down

Answer 7

Pulse- progressive fluoro

Question 8

how many ms of fluoro are required to obtain a single video frame

Answer 8

33 ms

Question 9

___ is the fraction of time an x-ray tube is energised

Answer 9

duty cycle

Question 10

Describe interrogation time

Answer 10

time required for x-ray tube to switch on

Question 11

Describe extinction time

Answer 11

Time required for x-ray tube to switch off

Question 12

CCD have ____ to make interrogation and extinction time < than ___

Answer 12

1. high frequency generators

2. less than 1 ms

Question 13

What is the function of a CCD

name principal advantages

Answer 13

turns light signal from output phosphor into electrical signal

1. Durable
2. Small size
3. Ruggedness

Question 14

What is an ADC and what is it function

Answer 14

Analog digital Converter

*Turns electrical signal from CCD into a digital signal to bread/stored by computer

Question 15

What does DAC stand for and what is its function?

Answer 15

Digital to analog converter

*Turns digital signal back to analog for manipulation at the console panel.

Question 16

What is the sensitive component of the CCD

Answer 16

layer of crystalline silicon

Question 17

How is spatial resolution of CCD determined by

Answer 17

1. Physical size

2. Pixel count

Question 18

Where is the ABS sensor located at

Answer 18

in the CCD

Question 19

List the advantages of flat panel IR over CCD II.

Answer 19

• No I.I
• Smaller & lighter
• Response is uniform over entire receptor
• Does not degrade with age
• Highest DQE

Question 20

C-arms are used mostly in ____ or ___.

Answer 20

mobile fluoroscopy

or in OR

Question 21

C-arms mostly utilized which type of receptor

Answer 21

CCD

Question 22

Describe last image hold

Answer 22

allows for last frame to be saved in the system so that radiologist can look at w/o having to expose the patient to unnecessary radiation

Question 23

_____ is the term for adjusting window levels to optimize the anatomy of interest

Answer 23

Gray scale processing

Question 24

term for subtraction of unnecessary anatomy from view

Answer 24

Digital subtraction angiography (DSA)

Question 25

Term for a subtracting technique in which contrast is injected and other structures are shown in white and contrast structures are dark (or visa versa)

Answer 25

Road mapping

Question 26

What minimizes pt. dose during digital fluorosocpy

Answer 26

pulsed progressive technology

Question 27

1. What does Rad stand for 2. What is it? 3. What quantity is it associated with?

Answer 27

Radiation absorbed dose -amount of energy absorbed by the medium at a particular point. ``` -Quant: absorbed dose SI unit (Gy) ```

Question 28

1. What does Rem stand for 2. What is it? 3. What quantity is it associated with?

Answer 28

1. Radiation Equivalent man 2. biological impact of varying types of radiation on various tissues. 3. Effective dose (Sv)

Question 29

Occupational dose equivalents are all stated in which radiologic quanity?

Answer 29

Rem

Question 30

Occupational Exposure limits are measured in ?

Answer 30

Dose equivalent

Question 31

____ is the product of absorbed dose in tissue X quality factor and other modifying factors at the area of interest

Answer 31

Dose quivalent

Question 32

____ is the amount of energy imparted by ionizing radiation per unit mass of irradiated material

Answer 32

Absorbed dose

Question 33

What is the Tissue weighting factors (Wt)

Answer 33

Takes into account various organ radiosensitivites -Greater Wt --> higher the radiosensitivity

Question 34

Define dose rate

Answer 34

Absorbed dose delivered per unit of time Expressed in rems

Question 35

Under normal operation ESD for fluoro should not exceed _____ & under boost mode, ESD shall not exceed ____

Answer 35

1. 10 R/min | 2. 20 R/min

Question 36

The quality of the x-ray beam is determined by ___?

Answer 36

HVL ( half value layer )

Question 37

Term for thickness/ layer of a materiel necessary to reduce the x-ray intensity to half its original value

Answer 37

Half vale layer ( HVL) | *measured in mm of AL*

Question 38

What determines quality of the x-ray beam and barrier thickness

Answer 38

HVL

Question 39

What does whole body dose consists of and what is the dose amount?

Answer 39

Head, trunk, prox. arms and legs .05 Sv/ year

Question 40

What are the annual occupational dose limits

Answer 40

* whole body= .05 Sv/year * Lens of the eye= .15 Sv/year * Skin & extremities = .5 Sv/year

Question 41

What are the annual public dose limits

Answer 41

1 rem annually or .002 rems in any 1 hour

Question 42

What does GSD stand for and what is it?

Answer 42

Genetically significant dose * It