Fluoroscopy

Used to require (blank) minutes of dark adaptation.

"15" minutes of dark adaptation

They used to use (blank) screens

"Fluoroscopic" screens

What is the typical X-ray tube current in fluoroscopy?

-5 mA -Can range from .5 to 5 mA -Compare this to a radiograph which can range from 50-1200 mA.

-What does Dynamic means:

-Always active or changing. -Having or showing a lot of energy. -Of or relating to energy, motion, or physical force.

Continuous Vs Pulsed Fluoro

-Continuous at 30 f/sec= higher dose. -Pulsed mode at 2 to 15 f/sec= lower dose. -Recommended to use lowest pulse mode required.

Distortion

-Distortion is an issue with image intensified fluoro. -Shape distortion results from inaccurately focused electrons. -Curved photocathode results in unequal magnification. -Also causes loss of brightness at periphery/ vignetting. -Too little x-rays can result in image noise.

Digital Fluoroscopy

-Early versions added analog to digital converter (ADC). -Video signal converted to bits (1s, 0s) determines gray. -The CCD improved digital.

What are the two ways in which the camera tube or CCD may be coupled to the ii?

-Fiberoptic bundle (does not allow for spot film) -Optical lens system (allows for spot film or cine)

Film cameras and VCR/DVD

-Film camera also photo-spot camera. -105mm or 70mm film roll. -Uses visible light from output phosphor to expose. -Can use VCR/DVD to record from TV monitor.

Automatic Brightness Control

-Function that maintains overall brightness and density. -It automatically adjusts kVp and mA. -Can be slow in adjusting for tissue density or thickness. -It works by monitoring the current (or output phosphor) and adjusts exposure level accordingly.

The (blank) the CF, the (blank) the efficiency of the image intensifier

-Higher -Greater

Viewing systems

-Historically used a mirror optics system. Now they use a TV system -Image on output phosphor must be converted to an electrical signal. -Two devices do this: the camera tube & charged couple device (CCD)

Fluoroscopy allows for?

-Imaging of the movement of internal structures. Can visualize function and motion in real time. -Commonly used for GI, vascular, and urinary studies, ect. -This often requires the use of contrast media.

Conversion factor

-Is Luminance of the output phosphor divided by input exposure rate. -Amounts to approximately 1% of brightness gain.

The Camera Tube

-Is either Vidicon or Plumbicon tube. -They are connected to the output phosphor by either fiber optics or lens system. -An electron beam (from the electron gun) sweeps the anode from left to right, top to bottom. This sweeping is called the raster pattern. -If there is light present when the electron beam sweeps, then a signal is transmitted.

Minification gain

-Is the reduction in size of the output phosphor image compared to the input phosphor image. -Is the square of the diameter of the input phosphor compared to the output phosphor. -Output phosphor sizes usually between 2.5cm or 5cm. -Input phosphor sizes vary from 10cm to 40cm.

As image intensifiers age, they become (blank) efficient, resulting in (blank) patient dose.

-Less -Increased

Many (blank) photons are needed to emit (blank) electron.

-Light photons -One electron

LCD

-Liquid crystal layer that is "twisted" -Receiving signal "untwists" and allows light to pass through pixel

Radiation safety in fluoro

-Reducing time reduces dose. -Increase collimation. -Use mag mode less.

Cassette spot film & cameras

-Spot film loaded into a slot between patient and ii. -Machine switches to radiographic mode, which increases mA. -Cassette can be divided into imaging sections. -Film reels used for recording dynamic imaging.

Charged Couple Device (CCD)

-The CCD is a light sensitive device that generates electric charge when stimulated by light. -Its charge is stored in a capacitor.

TV Monitor

-The purpose is to convert the electronic signal from the camera tube or CCD into a visible image. -Phosphors are on the inside of the glass front of a CRT monitor. -The phosphors get scanned by an electron gun emitting signal. -The phosphors emit light when hit by signal from electron gun. -This is what is visible to us.

When and by whom was fluoroscopy invented?

-Thomas Edison. -1896

Flat Panel Detector

-Used in place of ii. -Cesium iodide amorphous silicon indirect-capture. -Similar to DR systems, but used for dynamic imaging 60frames/sec.

Magnification Mode

-ii's are often multifield. -25/17/12 cm is a common type. These numbers refer to the diameter of input phosphor. -Using a small input phosphor results in a "magnified" view. -Magnification factor is direct proportion to ratio of diameters.

Flat Panel Detector (FPD) Digital

-mA in hundreds, similar to radiography. -Automatically pulsed 1-10frames/sec. -Generator controls = automatic dose rate, automatic exposure rate, take the place of ABC. -Vary kVp and mA. -Must switch on and off rapidly.

Bucky slot cover contains at least (blank) of lead-equivalent

.25mm

Protective curtain must contain at least (blank) lead-equivalent

.25mm

Personnel should wear aprons with (blank) lead-equivalent

.5mm

CF is approximately (blank) of brightness gain

1%

Characteristics of fiber optic devices

1) Are lighter 2) More rugged 3) cannot accommodate spot film.

Mag mode results in:

1) Better spatial resolution. 2) Better contrast resolution. 3) Higher patient dose. 4) Vignetting, which is the unfocused image at the periphery of the image.

Advantages of Digital Fluoroscopy over Image Intensified fluoroscopy:

1) Less bulky, less weighty, easier to manipulate. 2) Capable of operating in radiography mode. 3) Has a rectangular field of view. 4) Better contrast resolution. 5) Better spatial resolution regardless of field of view. 6) No pincushion distortion. 7) 50% lower radiation dose. 8) Less noise 9) Higher DQE

Characteristics of lens coupling

1) More susceptible to damage 2) Can use with spot film

Advantages of CCD over camera tube include:

1) The CCD is more sensitive to light (detective quantum efficiency DQE). 2) CCD shows no geomentric distortion (no pincushion). 3) CCD works better with digital systems. 4) CCD has higher signal to noise ratio (SNR). 5) CCD has better contrast resolution. 6) No warm up required. 7) No image lag. 8) No maintenance.

Federal law and most state statutes require that under normal operation, the ESD rate shall not exceed (blank)

100 mGy/min (10 R/min).

X-ray beam exposure at tabletop should not exceed (blank)

10R/min

Digital fluoroscopy systems must incorporate high-frequency generators with interrogation and extinction times of less than (blank)

1ms

The potential difference is of (blank)

25kV

SSD should at least be (blank) in portable unit

30 cm (12 inch)

SSD (source to skin distance) should at least be (blank) in stationary

38 cm (15 inch)

Each photo-electron produces (blank) times more light than was necessary to create it.

50-75 times more

Units without ABC (automatic brightness control) should not exceed (blank)

5R/min

-Coupling to the Image Intensifier - The two methods commonly used to couple the television camera tube or CCD to the image-intensifier tube are:

A, Fiberoptics B, Lens system

In conventional fluoroscopy, the milliamperage range is typically: A .0.5 to 5 mA B .20 to 50 mA C .100 to 300 mA D .400 to 600 mA

A. 0.5 to 5 mA

Electrons are (blank) from photocathode to an anode.

Accelerated

The numeric conversion factor value is equal to ________ of the brightness gain value. A. 0.001 B. 0.01 C. 0.1 D. 1.0

B. 0.01

The Bucky slot cover must have lead equivalent of ________. A. 0.10 mm B. 0.25 mm C. 0.50 mm D. 2.5 mm

B. 0.25 mm

A brightness gain of 40,000 would have a conversion factor of ________. A. 40 B. 400 C. 4000 D. 40,000

B. 400

In digital fluoroscopy, the x-ray beam is operated in a continuous mode similar to conventional fluoroscopy. A. True B. False

B. False

When spot filming during conventional fluoroscopic image intensification, the radiation dose to the patient is decreased. A. True B. False

B. False

What component of the image intensifier converts the visible light to electrons? A. Output phosphor B. Photocathode C. Input phosphor D. Electrostatic focusing lenses

B. Photocathode

A disadvantage of using the magnification mode during fluoroscopy is ________. A. decreased spatial resolution B. increased patient exposure C. decreased density D. decreased contrast

B. increased patient exposure

How do we calculate Brightness gain?

Brightness gain = minification gain X flux gain

When operating a stationary fluoroscopic unit, the source-to-skin distance (SSD) should not be less than ________. A. 25 cm (10 inches) B. 30 cm (12 inches) C. 38 cm (15 inches) D. 45 cm (18 inches)

C. 38 cm (15 inches)

What component of the image intensifier converts the exit or remnant radiation into visible light? A. Output phosphor B. Photocathode C. Input phosphor D. Electrostatic focusing lenses

C. Input phosphor

Brightness gain is a product of ________. A. minification gain and automatic brightness control B. flux gain and automatic brightness control C. minification gain and flux gain D. automatic brightness control and milliamperage

C. minification gain and flux gain

How do we measure luminance?

Candela per square meter

The photocathode is composed of (blank)

Cesium and Antimony

(blank) are used for day vision

Cones

For fluoroscopic units with automatic brightness control (ABC), the x-ray exposure at the tabletop should not exceed ________. A. 0.01 R/minute B. 0.1 R/minute C. 1.0 R/minute D. 10 R/minute

D. 10 R/minute

In conventional fluoroscopy, in order to view the images on a television monitor, the light intensities are converted by a ________. A. camera tube B. electrostatic lens C. charge-coupled device D. A or C

D. A or C

Which of the following standard safety practices is NOT used to reduce radiation exposure to the operator during fluoroscopy? A. Distance B. Time C. Shielding D. All of the above are used

D. All of the above are used

During fluoroscopy, releasing the pressure applied to the pedal or switch terminates the radiation exposure and is known as the ________. A. fluoroscopic timer B. intensification switch C. activation switch D. deadman switch

D. deadman switch

These compounds emit (blank)

Electrons

Large pattern of electrons must be reduced. (Blank) reduces electron stream.

Electrostatic lenses

What does ESD stand for?

Entrance skin dose

The light intensity emitted by the input phosphor (cesium iodide) is equal to the intensity of the (blank)

Exit radiation

The ii converts the x-rays into (blank)

High intensity visible light image.

The electrons pass through a (blank) in the middle of the anode.

Hole AKA focal point

The (Blank) receives the x-ray beam during fluoroscopy

Image Intensifier (ii).

X-rays that exit the patient are (blank) on the ii

Incident

They (x-rays) interact with the (blank)

Input phosphor (cesium iodide)

How do we measure exposure to an object?

Milli-Gray per sec

They then interact with an (blank)

Output Phosphor

Electrons pass through a hole in the anode to reach the (blank)

Output phosphor (composed of zinc cadmium sulfide)

Electrons move from (blank) to anode

Photocathode

This light then interacts with the (blank)

Photocathode

The process is called (blank)

Photoemission

(blank) used for night or dim vision have reduced visual acuity

Rods

Vidicon television camera tube and its principal parts.

The television camera tube converts the light image from the output phosphor of the image intensifier into an electrical signal that is sent to the television monitor, where it is reconstructed as an image on the television screen.

Extinction time

Time to turn off

Interrogation time

Time to turn on and be ready

X-rays are (blank) through the glass envelope

Transmitted

The ii exists within a (blank) to protect and support it.

Tube-glass or metal-housed within a metal structure.

The energy is converted to (blank)

Visible light

Image intensifiers have CF's of 50 to 300

Which corresponds to brightness gains of 5,000 to 30,000.

The output phosphor is composed of (blank)

Zinc cadmium sulfide

Electrons interact with output phosphor producing (blank)

light