what is the unit of measurement in figuring the conversion factor?
candela per square meter per milliroentgen per second
the numeric version of the conversion factor is approximately ________ of the brightness gain value.
the higher the conversion factor or brightness gain value, the _________ the efficiency of the image intensifier.
what is ABC and what does it do?
automatic brightness control
makes automatic adjustments to equipment exposure factors
maintains contrast and density by adjusting kVp and/or mA
amplifies video signal rather than adjusting exposure factors:
automatic gain control
what is the difference between automatic gain control and automatic brightness control?
automatic gain control amplifies video signal
automatic brightness control (ABC) adjusts exposure factors
name four main factors that affect image quality:
in fluoroscopy, what is contrast controlled by and what is it affected by?
controlled by amplitude of video signal
affected by scattered ionizing radiation and penumbral light scatter
in fluoroscopy, the resolution of video viewing is limited by:
the 525 line raster pattern of the monitor
how do raster patterns affect resolution?
the greater the number of lines in the raster pattern, the greater the resolution of the video signal
what is the primary cause of size distortion and how can it be combated?
combated by bringing image intensifier as close to patient as possible (thereby decreasing OID)
name two common shape distortions caused by the shape of the input screen:
pin cushion effect
____________ shape of the input screen helps to minimize _________________, but does not remove it all.
what is quantom motte, its cause, and how it is most commonly remedied?
blotchy, grainy appearance
caused by too little exposure
remedied by increasing mA
name two types of video viewing systems:
closed circuit television
video camera tube
a video viewing system in which there is a video camera coupled to an output screen and monitor:
closed circuit television
two types of video viewing systems in which a video camera tube is used:
Vidicon or Plumbicon tube
how are Vidicon and Plumbicon tubes different?
they have different target materials
Plumbicon has a faster response time than Vidicon
in video camera tubes, there is a __________ signal going in, and a __________ signal going out.
in a video camera tube, the cathode is the:
B. control grid
C. focusing coil
D. deflecting coil
E. electron beam
F. glass face plate
G. signal plate
I. video signal
name three parts that make up the anode of the video camera tube:
name two parts of the cathode of the video camera tube and their functions:
heating assembly: has an electron gun that controls thermionic emission
control grid: shapes the electron beam
describe the target of the video camera tube:
a thin insulating mica
a matrix of globules of photoconductive material
give the target materials of the two video camera tube types:
Vidicon: antimony trisulfide
Plumbicon: lead oxide (faster)
what is the function of the raster pattern?
accelerates the electron beam across the TV camera tube to the anode
what slows the raster pattern at the anode?
wire mesh in front of the target
in the video camera tube, shapes the electron stream into a single point:
electromagnetic focusing coils
in the video camera tube, causes the electron stream to scan the target in the raster pattern:
name two components of the video camera tube that contribute to the formation of the raster pattern:
electromagnetic focusing coils
in the video camera tube, a positively charged thin film of graphite:
the signal plate of the anode
what is the function of the anode target in the video camera tube?
it changes the light pattern to the electronic signal that is sent to the video system
list the forms of energy as they travel through the cathode ray tube:
from electrical, to electron, to light (which will be viewed at the monitor)
A. iron trap
B. electron gun
C. control grid
D. focus coil
E. deflecting coil
F. electron beam
H. fluorescent screen
I. light photons
a semiconducting device that emits electrons in proportion to the amount of light striking the photoelectric cathode:
video camera charged coupled device (CCD)
what does the CCD's fast discharge achieve?
it eliminates lag
name two advantages of the CCD over the video tube:
it operates at lower voltages
it is more durable
here are the notes i jotted down in class from the youtube video on CCDs we watched from the powerpoint. decipher and go over them at your own risk!!
CCDs made of silicon
the human eye is more sensitive to green light (closer to middle of light spectrum)
x-ray interacts, receptor receives the interaction, CCD receives it. With every x-ray interaction, releases negative charge (electrons)…capacitors in CCDs get more intensity (like from tissues, ligaments, etc), stores charge, then you’ve got the whole grid of reception with the CCD (the whole finished picture).
the areas with greater electrical charge have greater intensity. we want it to be changed to a digital form so we can see it.
in digital fluoroscopy, the image intensifier output screen is coupled to:
TFTs (thin film transistors)
in digital fluoroscopy, TFT photodiodes are connected to:
each pixel element
in digital fluoroscopy, resolution is limited out of concerns for
TFTs improve ___________________ and are used to display images on _______________.
an LCD screen
name four ways of recording the fluoroscopic image:
cine film systems
static spot filming systems
when recording the fluoroscopic image, what is a film size of note in digital fluoroscopy?
105mm chip film
name two types of dynamic systems used in recording the fluoroscopic image:
give measurements and rates specific to cine film systems for when the movie camera intercepts the image:
16mm and 35mm formats
records series of static exposures at high speeds
30-60 frames per second
what do cine film systems offer as compared to dynamic systems?
increased resolution (at the cost of increased patient dose)
list some common advantages and disadvantages of videotape recording:
(VHS and VHS-S)
often used today with the speech pathologist
allows playback in real-time after the procedure
limited storage space is a disadvantage
in static spot filming systems, what changes in mA are necessary in comparing fluoro and radiography modes?
fluoro mode: 2 to 5 mA
radiography mode: 100 to 1200 mA
in static spot filming systems, which mode increases the dose to the patient and personnel in the fluoroscopy room?
radiographic mode increases dose as compared to fluoro mode
where is the film located in static spot filming systems?
stored in a lead compartment until an exposure is ready to be made
in static spot filming systems, what size film is utilized, and how can it be divided for exposures?
9x9 film size
divides into 1 on 1; 2 on 1; 4 on 1; and 6 on 1
in static spot filming, what allows the film to be exposed photographically?
a beam-splitting mirror during the exposure
in static spot filming, since the process is photographic, how must it be developed?
in a wet processor in a darkroom
in static spot filming, how many frames per second can be taken?
up to 12 frames per second
taking an image using the image intensifier causes _________ dose to the patient as compared to the spot film.
describe digital fluoroscopy with the use of a CCD:
uses the CCD to generate an electrical signal
the signal is sent to an ADC
allows for post processing and electronic storage and distribution
name the three pillars of radiation protection and who they are meant to protect
time, distance, shielding
patient, radiologists and technologists, others
in patient protection, list the minimum SSDs (source to skin distances) for both mobile and stationary equipment:
mobile equipment: 12" minimum SSD
stationary equipment: 15" minimum SSD
for patient protection, when do audible alarms sound in the use of fluoroscopy?
at 5 minutes
what is the maximum exposure rate of the x-ray beam at tabletop that is deemed acceptable by the FDA?
maximum of 10 R/min: for units with automatic brightness stabilization (ABS)
maximum of 5 R/min: for units without automatic brightness stabilization (ABS)
(typically 1-3 R/min is used)
give typical exposure rates for cinefluoroscopy, cassettes, and 105 mm film:
cinefluoroscopy: 7.2 R/min
cassettes: 30 mR/exposure
105 mm film: 10 mR/exposure
the minimum required shielding required for lead gloves and thyroid shields:
.25 mm lead equivalency(by the NCRP No. 102)
the minimum required shielding required for lead aprons:
.5 mm lead equivalency (by the NCRP No. 102)
describe the angle and level of most scatter radiation in the fluoro room:
90° angle to the incident beam
the level of the radiologist's/technologist's gonad area
the minumum required shielding for the primary barrier of the fluoro tower's image intensifier:
2.0mm of lead equivalency (by the FDA)
the minimum required shielding for the protective curtain:
.25 mm lead equivalency (by the NCRP No. 102)
the minimum required shielding for the bucky slot cover: