Radiation Saftey and The Machine

what is it (Intro to Diagnostic Imaging)

air

what is it (Intro to Diagnostic Imaging)

fat

what is it (Intro to Diagnostic Imaging)

soft tissue

what is it (Intro to Diagnostic Imaging)

bone

what is it (Intro to Diagnostic Imaging)

lead

Diagnostic value is related to the … (Intro to Diagnostic Imaging)

quality of the image

High quality images = (Intro to Diagnostic Imaging)

High diagnostic value

Low quality images = (result + consequence) (Intro to Diagnostic Imaging)

Low diagnostic value/Misdiagnosis

photons have — energy to pass through tissues (Intro to Diagnostic Imaging)

high

X Ray machines turn electrical current into — — — (Intro to Diagnostic Imaging)

high energy photons

Electrical current flows through (Intro to Diagnostic Imaging)

cathode

the cathode is —- charged (Intro to Diagnostic Imaging)

negativly

the anode is — charged (Intro to Diagnostic Imaging)

positively

the anode attracts — (Intro to Diagnostic Imaging)

electrons

what is it (Intro to Diagnostic Imaging)

stator

what is it (Intro to Diagnostic Imaging)

rotor

what is it (Intro to Diagnostic Imaging)

bearings

what is it (Intro to Diagnostic Imaging)

W/Re anode

what is it (Intro to Diagnostic Imaging)

thin exit window

what is it (Intro to Diagnostic Imaging)

evacuated glass bottle

what is it (Intro to Diagnostic Imaging)

cathode support

what is it (2) (Intro to Diagnostic Imaging)

filament and focusing cup

We can control 3 parameters to alter the nature of the X Ray beam produced and so optimize our radiographic image (Intro to Diagnostic Imaging)

1. kVp

2. mA

3. time

what does kVp stand for (Intro to Diagnostic Imaging)

kilovolts

what does mA stand for (Intro to Diagnostic Imaging)

milliamps

kVp is the — with which the photons move (Intro to Diagnostic Imaging)

Power

Higher kVp gives the photons … (Intro to Diagnostic Imaging)

more power to penetrate tissues.

Increasing kVp will — contrast (Intro to Diagnostic Imaging)

decrease

mA is the — — of photons in the beam (Intro to Diagnostic Imaging)

total number

Higher mA increases the total number of photons and —- the image overall (Intro to Diagnostic Imaging)

darkens

Higher mA increases the total number of photons and — contrast (Intro to Diagnostic Imaging)

reduces

long contrast is — kVp, — mAs (Intro to Diagnostic Imaging)

high, low

short contrast is — kVp, — mAs (Intro to Diagnostic Imaging)

low, high

X-Rays are a type of — radiation (Radiation Safety)

ionizing

X Rays are highly penetrating but have low (Radiation Safety)

LET

what does LET stand for (Radiation Safety)

linear energy transfer

Risks are — and increased based on —- —- —- to radiation (Radiation Safety)

CUMULATIVE, TOTAL LIFETIME EXPOSURE

define Inverse square law of radiation intensity (Radiation Safety)

The beam intensity at the image receptor is directly proportional to the exposure parameters mAs

what ppe should be worn (5) (Radiation Safety)

1. 0.5mm lead gown

2. thyroid protector

3. gloves

4. glasses

5. dosimeter

what is the dosimeter for (Radiation Safety)

to allow monitoring of excessive exposure

PPE only protects from (Radiation Safety)

scatter radiation

NO PART OF THE TECHNICIANS ANATOMY SHOULD BE PLACED IN … (Radiation Safety)

THE PRIMARY BEAM

who discovered x-rays (The Basics of Atoms and Electricity)

Wilhelm Conrad Roentgen

when were x-rays discovered (The Basics of Atoms and Electricity)

1895

what are the12 unique properties of x-rays (The Basics of Atoms and Electricity)

1. Are invisible

2. Are electrically neutral

3. Have no mass

4. Travel at the speed of light in a vacuum

5. Cannot be focused by a lens

6. Form a polyenergetic (heterogeneous) beam

7. Can be produced in a range of energies (kV)

8. Travel in straight lines

9. Cause fluorescence in certain substances

10. Can cause chemical changes to occur in radiographic and photographic film

11. Can be absorbed or scattered by tissues in the body; can produce scattered and secondary radiation

12. Can cause chemical and biological damage to living tissue

define element (The Basics of Atoms and Electricity)

Smallest particle of a substance

define atom (The Basics of Atoms and Electricity)

Smallest particle of an element

the nucleus of atoms contains (2) (The Basics of Atoms and Electricity)

1. protons

2. neutrons

— circle the nucleus in rings (The Basics of Atoms and Electricity)

electrons

define thermionic emission (The Basics of Atoms and Electricity)

heat is applied to the cathode of the x-ray tube, electrons are “boiled off”

how are x-rays made (4) (The Basics of Atoms and Electricity)

1. boiling electrons off

2. exposure switch is closed

3. “photons” or energy packets are drawn across from the cathode to the anode

4. interacts with the anode

what charge do protons have (The Basics of Atoms and Electricity)

positive

what charge do neutrons have (The Basics of Atoms and Electricity)

none

none

what charge are electrons (The Basics of Atoms and Electricity)

negative

X-rays created from converting — into — (The Basics of Atoms and Electricity)

matter, energy

Principle characteristic of “matter” (2) (The Basics of Atoms and Electricity)

1. Matter occupies space

2. Mass or weight

Energy’s principle characteristic (2) (The Basics of Atoms and Electricity)

1. Movement or motion

2. The ability to do work

what kind of energy is used in radiography (The Basics of Atoms and Electricity)

electromagnetic

amplitude is the —- of waves (The Basics of Atoms and Electricity)

height

frequency is the —- between waves (The Basics of Atoms and Electricity)

wavelength

frequency is connected to the kilovoltage used to … (2) (The Basics of Atoms and Electricity)

1. penetrate the tissue of the patient

2. the time that is set to produce the x-rays.

Shorter wavelengths with higher frequencies penetrate the tissue —- effectively than long wavelengths with low frequency (The Basics of Atoms and Electricity)

more

A photon may be pictured as a … (The Basics of Atoms and Electricity)

small bundle of energy.

As energy increases, frequency —- (The Basics of Atoms and Electricity)

increases

heat dissapation is —-% heat/—-% x-rays (Diagnostic X-Ray Production)

99, 1

what are the 4 x-ray generator settings (Diagnostic X-Ray Production)

1. voltage

2. current

3. time

4. resistance

what are the units for voltage (Diagnostic X-Ray Production)

V

define voltage (Diagnostic X-Ray Production)

the speed with which the electrons in the electric current transfer energy along the circuit.

what are the units for high voltage (Diagnostic X-Ray Production)

kV

high voltage produces (3) x-rays (Diagnostic X-Ray Production)

1. short-wavelength

2. high frequency

3. highly penetrating

current is also known as (Diagnostic X-Ray Production)

amerage

what is the unit for current (Diagnostic X-Ray Production)

upper case ‘i’

define current (Diagnostic X-Ray Production)

to measure the electric current that activates the x-ray tube.

the x-ray unit consists of a closed circuit with 5 main criteria: (Diagnostic X-Ray Production)

1. It must have enough power to eventually produce x-rays.

2. It must have selections where the power can be increased or decreased as necessary.

3. The electric current must travel in the same direction through the x-ray tube.

4. There must be a way to produce free electrons with enough energy to produce x-rays.

5. There must be an efficient way to dissipate the heat that results in the interaction of the photons and the anode.

circuit breakers acts as a (Diagnostic X-Ray Production)

fuse

how do circuit breakers act as fuses (Diagnostic X-Ray Production)

If the voltage or current is set too high, or if a component malfunctions, the circuit breaker will cut the power to the unit

define fuse (Diagnostic X-Ray Production)

safety devices that will mechanically interrupt the flow of electricity if a problem arises that would overheat the circuit

define ground wire (Diagnostic X-Ray Production)

Redirects current flow of excess electrons if circuit is broken

what color is the ground wire usually (Diagnostic X-Ray Production)

green

operating console is aka (Diagnostic X-Ray Production)

generator

voltage controls — —- (Diagnostic X-Ray Production)

penetrating power

current controls (2) (Diagnostic X-Ray Production)

1. number of photons

2. density of image

power (WATT) equation (Diagnostic X-Ray Production)

Power (WATT) = voltage (V) X Current (A)

purpose of line voltage compensator (Diagnostic X-Ray Production)

Stabilizes incoming power line

define direct current (Diagnostic X-Ray Production)

Source of power near the end user

define Alternating Current (Diagnostic X-Ray Production)

One positive pulse and then one matching negative pulse

how many cycles are in alternating current (Diagnostic X-Ray Production)

120 cycles/sec

define transformers (Diagnostic X-Ray Production)

Transformers step up (increase) the power at one end of the journey and then step down (decrease) the power at the destination

define rectifiers (Diagnostic X-Ray Production)

Allow current to keep moving in one direction within x-ray unit

What is the problem with single-phase circuits (Diagnostic X-Ray Production)

The problem that arose was the long exposure time due to the low power of these units and the loss of power as the voltage dropped during the exposure with the completion of each pulse

what are 3-phase circuits used for (Diagnostic X-Ray Production)

large animal chest and abdominals

why is 3-phase circuits used for large animal (Diagnostic X-Ray Production)

high milliamperes (mA) combined with short times (seconds) are necessary to image large-animal chests and abdomen

what are the 3 kinds of circuits (Diagnostic X-Ray Production)

1. single-phase

2. three-phase

3. high-frequency

what are the 3 components of the x-ray unit (Diagnostic X-Ray Production)

1. High-voltage transformer / high-tension transformer

2. X-ray generator

3. X-ray tube

define High-voltage transformer / high-tension transformer (Diagnostic X-Ray Production)

It is connected to the hospital power lines and uses the power supplied to the hospital by the outside power lines.

define X-ray generator (Diagnostic X-Ray Production)

receives its power from the highvoltage transformer and sends it through the circuit to the rectifiers and then to the x-ray tube

define x-ray tube (Diagnostic X-Ray Production)

it is here that the x-rays are produced

what is in the x-ray tube (7) (Diagnostic X-Ray Production)

1. Cathode

2. anode

3. Near vacuum

4. Power must enter thru the cathode

5. Heat will exit through stem of the anode

6. Stem is mounted on ball bearings which are coated in light oil

7. Every x-ray tube is shielded with a metal covering, which restricts most off-focus radiation from exiting the tube other than at the tube port.

the x-ray tube process to produce x-rays (5) (Diagnostic X-Ray Production)

1. the exposure switch is closed

2. the electrons are drawn across to the anode by electromagnetic force

3. they are stopped very suddenly by the density of the metal of the anode.

4. They react immediately by losing speed

5. converting the forward motion to energy, which results in heat and x-rays (99% heat and 1% x-rays).

define thermionic emission (Diagnostic X-Ray Production)

emission due to heating