Rad 102-1: Part 1

7 components of radiographic equipment (1)

1. control panel

2. transformer

3. x-ray tube

4. tube stand

5. X-ray table

6. upright cassette holder

7. bucky system

Control panel (1)

the basic one contains selectors and indicators used to power up the unit and manipulate the stregth of the x-ray beam

Control panel controls features in fluroscopy like (1):

1. kVp selector

2. mA selector

3. exposure switch

Transformer: (2)

steps up incoming voltage to kilovoltage

X-ray tube (2)

contains the anode and cathode

tube stand (2)

suspends tube over patient

X-ray table (3)

its movable, some tables can be angles 30 degrees head down or fully upright to 90 degrees

Upright casette holder, it is also known as: (3)

upright bucky

bucky system (3)

body parts larger than 10cm require the use of a lead grid to recude the amount of scatter radiation reaching the film.

The bucky mechanism… (3)

has a grid that moves back and forward during the exposure to better reduce scatter

A.E.: Technique chart (4)

used in determining the proper exposure according to the part to be radiographed and its size

A.e. : Calipers (4)

Measurement for part thickness is always from entry to exit of the CR through the part that is being examined.

A.E.: Protractor (4)

measures the angle of the plane with a base that is parallel with the table

A.e. : CR Cassettes (4)

used to hold and expose the image receptor. They have different sizes.

A.E.: Sand bags (5)

used for immolization and positioningA

A.e.: Radioluscent position blocks (5)

used to aid in mobilization and patient comfort during positioning

A.e. Lettter markers (5)

used to identify side of body on a radiograph as well as other needed informaiton

A.E. Safety (6)

The technologist is responsable for the safety of everyone in the exposure room to include themselves as well as the safe use of all equipment and supplies.

Additional equipment: (4-6)

1. technique chart

2. calipers

3. protractor

4. CR Cassettes

5. sand bags

6. radioluscent positioning blocks

7. letter markers

8. safety

What is the X-ray machine indentification and purpose (7)

x-ray units are classified as “diagnostic” or “therapeutic”

What are x-ray machines usually identified according to? (7-8)

1. energy of x-ray produced

2. the purpose for which those xrays are intended

3. usually operate at maximum voltages ranging from 25 to 150 kVp and a tube current from 100 to 1200 mA

what are the components every xray machine mut have regardless of its design? (9-10)

1. xray tube

2. control/operating console

3. high voltage generator

xray tube (9)

contained in an inaccessible protecting housing that guards against excessive radiation exposure and electric shock. it has anode and cathode

Control/ operating console(9)

allows the control of: tube current and voltage for proper quantity (mA) and quality (kVp)

High voltage generator (10)

Converets low voltage supplied at the autotransformer to the kVp necessary fro xray production

Types of application: Tomographic unit (11)

have tubes that move in an arc during exposure

types of application: Magnetic Resonance Imaging (MRI or MR) suite (12)

computerized sectional images using magnetism and radio frequencies

Beam restriction devices (15)

tools the readiographer can use to limit the amount of scatter radiation reaching the IR

purposes of beam restriciton: (15)

1. limit patient exposure

2. reduce amount of scatter produced within the patient

3. improvement of image quality

Factors that increase the production of scatter radiation (15)

1. high kVp

2. Volume of tissue irrated (thicker body part)

As the volume of irrated tissue increases (16)

the amount of scatter produced increases

Decreasing the x-ray beam field size and amount of tissue irradiated causes: (16)

1. decrease scatter radiation production

2. decreased patient dose

3. increased contrast

Aperture diaghragm (16)

flat sheet of metal, usually lead with a hole cut in the center and attached to the xray tube port

Collimator (17)

most commonly employed beam restrictor in radiography

Materials used in xray filter (18)

most common material- alumminum

Aluminum (18)

AL/Eq

inherent filtration (19)

filtration that is a result of the composition of the rube and housinga

Types of components of xray filtration : application (19)

general purpose xray tubes use 0.5 mm aluminum equivalent(Al/Eq)

Types of compensating filters: (21)

1. Wedge filter

2. bow-tie-shaped filters

Wedge filter (21)

used to radiograph body parts that varies considerable, such as the foot

Bow-tie-shaped filters (21)

used in some CT scanners to compensate for the shape of the head or body

Automatic Exposure Control (AEC) systems (24)

device that measures the quantity of radiation reaching the image receptor and automatically terminates the exposure when the image receptor has received radiation intensity.

Types of AEC (24)

1. phototimer

2. Ionization chamber

Phototimer device (25)

Xray beam pases through the patient, tabletop, and casette before it strikes a phototimer

Components of a phototimer device (25)

1. flurescent screen

2. photomultiplier tube

3. capacitor

   1. thyratron

Fluroscent screen (25)

absorbs xrays and produces light photon, they get directed toward a photomiltiplier tube

photomultiplier tube (25)

produces electrons from the light photons received from the flourescent screen

capacitor (25)

reeives electrons from the photomultiplier tube and is charged until it reaches a present value. Once it does, it discharges, triggering the thyrathon and opening the relay to terminate exposure

thyratron (25)

regulates the exposure automatically

Ionization chamber device (25)

xray beam passes through the patient and tabletop before striking the ionization chamber.

Back up timer (26 )

cannot exceed the tube limit and should be set at 150% (or 1.5 times) of the anticipated manual exposure mAs

If the AEC fails to terminate the exposure, the second safety circuit terminates at (26)

600 mAs for exposures over 50 kVp

At what mAs can the secondary circuit terminate exposures below 50 kVp? (26)

2,000 mAs

AEC control panel, to image the use of AEC, the radiologist selects the appropriate: (26)

1. kVp

   1. mA

Kvp in the AEC control panel (26)

selected according to the specific anatomical part that is being examined

mA in the AEC control panel (26)

the AEC compensates for increases/decreases in mA

Component of mobile set: Generators (28)

specialized generator specifically designed for mobile quipment

generators: capacitors (28)

discharge and battery-powered units are the most common

what generator produce a constant potential output? (28)

capacitor-discharge units

What generator produce output that is esentially 3 phase? (29)

battery powered units

Drive system (29)

power is available to drive the unit itslef with a baterry powered unit (some units do not have a drive system)

application of mobile radiographic units: (29) Locations where mobile radiography may be done

1. emergency room

2. surgery or operating room

3. bedside

two major categories of mobile equipment (30)

1. mobile light duty units

2. full-power institutional units

Battery-driven, Battery-operated (30)

powered at 10-16 rechargable sealed, lead-acid 12-volt batteries connected in series

Baterry driven (30)

variable speeds up to 2.5 -3.0 mph, driving range of up to 10 miles on a full charge

radiation safety (34)

1. wear lead when operating a portable unit and provide lead aprins for the patient, staff, and other close patients.

2. stand at least 6 feet away from the xray source.