Digital fluoroscopy Flashcards
____ is the smallest element of a digital image
pixels
_____ image is usually composed of a two dimensional matrix of pixels
digital image
____ = the number of pixels in each row and column of the image
Matrix size
relating to the matrix how is the image size more faithfully reproduced >
as matrix size increases and pixel size decreases
Digital fluoro operates in ___ mode ???
radiographic mode
Greater than 100 mA
Standard fluoro operates in ___ mode
fluoro mode
Less than 5 mA
____ is the pulsed beam method utilized in digital fluoro to keep pt. dose down
Pulse- progressive fluoro
how many ms of fluoro are required to obtain a single video frame
33 ms
___ is the fraction of time an x-ray tube is energised
duty cycle
Describe interrogation time
time required for x-ray tube to switch on
Describe extinction time
Time required for x-ray tube to switch off
CCD have ____ to make interrogation and extinction time < than ___
- high frequency generators
2. less than 1 ms
What is the function of a CCD
name principal advantages
turns light signal from output phosphor into electrical signal
- Durable
- Small size
- Ruggedness
What is an ADC and what is it function
Analog digital Converter
*Turns electrical signal from CCD into a digital signal to bread/stored by computer
What does DAC stand for and what is its function?
Digital to analog converter
*Turns digital signal back to analog for manipulation at the console panel.
What is the sensitive component of the CCD
layer of crystalline silicon
How is spatial resolution of CCD determined by
- Physical size
2. Pixel count
Where is the ABS sensor located at
in the CCD
List the advantages of flat panel IR over CCD II.
- No I.I
- Smaller & lighter
- Response is uniform over entire receptor
- Does not degrade with age
- Highest DQE
C-arms are used mostly in ____ or ___.
mobile fluoroscopy
or in OR
C-arms mostly utilized which type of receptor
CCD
Describe last image hold
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
_____ is the term for adjusting window levels to optimize the anatomy of interest
Gray scale processing
term for subtraction of unnecessary anatomy from view
Digital subtraction angiography (DSA)
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)
Road mapping
What minimizes pt. dose during digital fluorosocpy
pulsed progressive technology
- What does Rad stand for
- What is it?
- What quantity is it associated with?
Radiation absorbed dose
-amount of energy absorbed by the medium at a particular point.
-Quant: absorbed dose SI unit (Gy)
- What does Rem stand for
- What is it?
- What quantity is it associated with?
- Radiation Equivalent man
- biological impact of varying types of radiation on various tissues.
- Effective dose (Sv)
Occupational dose equivalents are all stated in which radiologic quanity?
Rem
Occupational Exposure limits are measured in ?
Dose equivalent
____ is the product of absorbed dose in tissue X quality factor and other modifying factors at the area of interest
Dose quivalent
____ is the amount of energy imparted by ionizing radiation per unit mass of irradiated material
Absorbed dose
What is the Tissue weighting factors (Wt)
Takes into account various organ radiosensitivites
-Greater Wt –> higher the radiosensitivity
Define dose rate
Absorbed dose delivered per unit of time
Expressed in rems
Under normal operation ESD for fluoro should not exceed _____
& under boost mode, ESD shall not exceed ____
- 10 R/min
2. 20 R/min
The quality of the x-ray beam is determined by ___?
HVL ( half value layer )
Term for thickness/ layer of a materiel necessary to reduce the x-ray intensity to half its original value
Half vale layer ( HVL)
measured in mm of AL
What determines quality of the x-ray beam and barrier thickness
HVL
What does whole body dose consists of and what is the dose amount?
Head, trunk, prox. arms and legs
.05 Sv/ year
What are the annual occupational dose limits
- whole body= .05 Sv/year
- Lens of the eye= .15 Sv/year
- Skin & extremities = .5 Sv/year
What are the annual public dose limits
1 rem annually
or .002 rems in any 1 hour
What does GSD stand for and what is it?
Genetically significant dose
- It
