Lesson 1: X-ray Production And Safety

A _____________ device is used to restrict the size of the X-ray beam and reduce the amount of scatter radiation.

Collimating

________ is important for greatly reducing the dose of x-rays that patients receive by limiting the level of scattered x-rays so only the area of interest would be exposed to the radiation.

Collimation

Which device is used to control the size of the primary beam?

Collimator

Digital images are stored in a _____________ format.

DICOM

Which of the following is the most vulnerable to radiation? Head, hands, DNA, eyes

DNA

How does scatter radiation affect the image?

Decreases the detail seen on the film by causing a thin fog of gray to cover it.

When are grids used?

During x-ray when any body part has a thickness of 10cm of more.

Who is the primary source of scatter radiation?

Patient

What is a lead letter marker?

This marker is made of small lead letters placed in a plastic holder. The lead letters show up on the film when the marker is placed in the primary beam at the time of the exposure.

What is the purpose of the control panel?

Tells the machine which settings are needed to emit the proper amount of radiation to produce a good radiograph image.

What is a bucky tray?

The Bucky tray is located below the table

What is Fluoroscopy?

another form of radiology. Fluoroscopy combines single x-rays to make a video of the radiographic images.

To help dissipate heat, the x-ray tube contains

oil

The transformer provides the radiograph machine with ____

power

The electromagnetic spectrum can be measured in three ways:

-Energy, measured in electron-volts (eV) -Frequency, measured in hertz (Hz) -Wavelength (l),measured in meters (or nanometers or kilometers)

How are grids classified? Describe each one.

-imprinting system (flasher): this system have a special lead blocker that prevents radiation from getting to one corner of the film. An index card containing animals info is placed in this corner. -Graphite tape (lead tape): tape contains a material much like ground-up pencil lead. You can use a pen or pencil to write on it, the graphite is moved to the side and a line is formed. *these differ in that lead tape needs to be on the film at the time of exposure.

Functions of x-ray cassettes

-protect the film from debris -prevent film from bending -sturdy for multiple use -are light tight. Light will ruin a film. -hold intensifying screens

What are the two components of a transformer? Describe them.

-step-up transformer: The step-up transformer raises the voltage coming into the machine from 220 volts to about 125,000 volts. -step-down, or filament, transformer: The filament transformer then reduces the volts to a preset number based on the milliamperage (mA) setting.

How to clean a cassette?

-use a damp cloth to wipe the outside of the cassette to remove outside debris -interior cleaning: a commercially available cleaner and a gauze sponge can be used to gently wipe the screens while the cassette is empty. Allow the screens to sit open in a vertical position to dry fully (for up to 30 minutes) before placing film back into the cassette

the thickness requirement for radiographic protective apparel is _____lead equivalent

0.5mm

What percentage of radiation is produced in comparison to the amount of heat produced?

1 to 99

Grids are generally used when a body part is at least _____ centimeters thick.

10

How is the image on the film made?

95% of the image is made up by the light that comes from the screens, not the x-rays themselves.

When x-rays are produced in the process reviewed above, heat is the main product. In this process, ____ percent of the energy released is heat and _____ percent of the energy is released as x-rays

99, 1

What is a dosimeter?

A badge used to record your radiation exposure level for a certain period of time.

List three functions of a cassette.

A cassette is used to hold the intensifying screens, keep the film clean, and keep light away from the film

What is a dosimeter? What is it used for?

A dosimeter is a device worn at neck level outside of the gown during radiographic procedures to monitor the amount of radiation the worker is exposed to in a given period of time.

The program established to ensure radiation exposure is kept as low as possible is:

ALARA

The x-ray tube consists of what two parts?

Anode and cathode

________ collimators perform positive beam limitation.

Automatic

Which of the following is not found on a control panel?

Bucky selector

Xray tube: Electrons are generated at the ______ by the filament. Voltage is passed between the cathode and ________. The electrons pass from the cathode side of the tube to the anode side of the tube at great speeds and collide with the target on the anode. X-rays are then produced.

Cathode Anode

Electrons are generated at the _____________ end of the X-ray tube and travel to the _____________.

Cathode; anode

Film radiographs are generally filed in folders or envelopes containing what information?

Client's name Patient's name Date Body part and views taken

Radiology logs are logs help to keep track of the settings used to perform the radiographs, making it easier to take comparison films at a later date. What information do these logs contain?

Client's name Patient's name Date Body part being radiographed Position kVp and mAs settings used Initials or signature of the technician

How is the electromagnetic spectrum measured?

Energy (eV), frequency (Hz), and wavelength (l)

Primary protect clothing includes which of the following

Eye protection, thyroid collars, gloves, aprons.

The _____________ _____________ allows for the excited electrons to be released from the cathode in a straight pattern directed toward a focused target on the anode.

Focusing cup

What is the minimal radiation safety protection necessary when in the room during the x-ray exposure?

Gowns and gloves of 0.5 mm lead equivalent are mandatory at all times when personnel are present in the room at the time of the exposure. It's highly recommended that eye protection and thyroid protection also be worn.

What is the purpose of a grid?

Helps filter out scatter radiation that is harmful to the film's detail. The grid only lets only the good primary beam through to the film.

Why is it important to keep cassettes and screens clean?

If any particle gets inside the cassette it will block the light from hitting the crystals, therefore, the crystals will not be able to work.

Which of the following is a property of an x-ray cassette?

It protects the film from debris and dirt, prevents bending of the film, holds the intensifying screens.

How long can it take for radiation to have an effect on your body?

Many years

How long does it take for damage of radiation to show its effects?

Many years or even generations

Standard patient exposure is measured in:

Milliroentgens

What's the difference between primary and scatter radiation?

Primary radiation is the radiation that's found in the x-ray beam leaving the machine. This is the useful beam that's used to make the image on the x-ray film. Scatter radiation is any radiation found outside the primary beam. It's less energetic and doesn't add to the useful image being produced. This scatter radiation is also harmful to the personnel in the room at the time of the exposure.

What does the mAs setting on the X-ray machine control?

Quantity of the electrons released

Radiation levels are measured in ____, ____, and ______.

RAD,REM, and Sievert.

__________ is the transmission of energy through space or a material

Radiation

Explain how you can reduce radiation exposure.

Radiation exposure is reduced by time, distance, and shielding. Time means getting the image right the first time (proper settings and positioning). Distance means being as far away from the primary beam and patient as possible. Shielding means wearing personal protective equipment.

What is primary beam

Radiation going into the patient

X-ray cassettes are made up of what?

Radiolucent front cover (penetrable to x-rays) and lead foil backing.

______ are used to supply all the needed electrical current to the x-ray machine

Rectifiers

The _____________ anode allows for greater dissipation of heat.

Rotating

X-rays are similar to visible light but with a much _____________ wavelength, which gives them _____________ energy.

Shorter; greater

What does the control panel do?

The control panel allows the operator to control the x-ray machine and adjust the settings as needed

Radiology equipment is composed of what?

The control panel, cassettes, and grids.

Where is the grid located? What is its purpose?

The grid is located under the table and above the cassette holding tray. Its purpose is to prevent scatter radiation from reaching the x-ray film when the cassette is placed in the holding tray.

Technique is the term used to describe

The term used to describe all the factors set on the machine. The kilovoltage, the milliamperage, and the time.

What does technique mean?

The term used to describe all the factors set on the machine. The kilovoltage, the milliamperage, and the time.

Technique is a term used for the major factors set on a radiology machine control panel. What factors are included in this term?

The three factors normally set on the machine that make up the general term "technique" are kV, mA, and time (seconds).

There are two groups of people who should never be allowed in the radiation area. Who are they?

The two groups of people who are never allowed in the radiation area for any reason are pregnant women and anyone under the age of 18 years.

Why is the x-ray tube enclosed in glass?

The x-ray tube is enclosed in glass so a vacuum can be created.

What are radiation logs?

They help track techniques used on repeat patients and radiation exposure of staff.

Why are short wavelengths better than long wavelengths for radiograph production?

They're very powerful and the potential for penetration through a mass is better.

What is "time" on the xray machine?

Time is the duration (in seconds) that the anode is receiving electrons and is therefore positively charged. -Time and mA are usually opposite. Time-short, mA- high.

What methods help reduce radiation exposure?

Time: Make sure the image taken the first time is the correct image with the correct exposure and correct positioning. Distance: Stay as far away from the primary beam and patient as possible. -the best method is to not be in the room if possible (with sedation, drugs etc) Shielding: Wear proper personal protective equipment.

What's the purpose of a rotating anode?

To dissipate heat more quickly and prevent damage to the anode

The cathode contains filaments composed of ____________

Tungsten

types of radiation?

Ultraviolet xray gamma alpha beta infrared microwave radio

Portable X-ray units possess all of the following features except:

Use a rotating anode

What are intensifying screens (located on the inside of the cassette)?

Used to produce a better image. Screens are made of crystals. These crystals glow and produce light when x-rays hit them. Certain crystals with fluoresce and emit energy in the form of colored light (blue or green) when they absorb x-rays -These crystals (also called phosphors) gives off these colored radiations in amounts that correspond with the amount of radiation that hits them

Why is it important in veterinary radiology to keep the mA setting as high as possible?

When the milliamperage is kept as high as possible, this means the exposure time can be as low as possible. It's important because the number one artifact in veterinary radiology is motion from a moving animal. Also, shorter exposure times decrease radiation exposure to personnel who are restraining the animal.

When does secondary or scattered radiation occur?

When the primary beam interacts with the patient

The normal electrical current in the United States is ________ current (AC), in which electrons switch directions many times per second. The cathode requires direct current (DC).

alternating

The _____ is the side of the x-ray tube that houses the target, which produces x-rays when hit by electrons.

anode

The control panel consists of:

basic components are the same: on/off switch, kVp selector, mAs selector, time selector, x-ray prep, and x-ray exposure button.

A Bucky tray is a tray that holds the

cassette below the table.

When measuring an animal body part with a caliper to set the technique, the unit used is the

centimeter

A dosimeter should be worn on your

collar during radiographic exposures.

The purpose of a rectifier is to

convert alternating current to direct current.

Wavelength is the size of the wave from ____ to ______

crest to crest

Two types of radiographs used in practice today are ____ and ________ radiographs.

film and digital.

The components of the x-ray tube have to be made to withstand high temperatures since ____ is the main form of energy released in the x-ray production process.

heat

During exposure to radiation, _______ ________ is ionized, which results in toxic products being released that can damage components of the cell such as deoxyribonucleic acid (DNA).

intracellular water

Radiographic envelopes generally do not contain what information?

kVP and mAs setting

The acceleration of the electrons and their striking energy is determined by the:

kVp

Types of protective clothing when xraying

lead gown, lead gloves, lead glasses and lead thyroid shield.

Explain milliamperage (mA) and kilovoltage (kV)

mA: number of x-rays that will be emitted from the machine. The more x-rays emitted, the more x-rays will hit the film and the darker it will become kV: penetrating power of the beam. If the kilovoltage is high, the beam will go through thick body parts. If the kilovoltage is low, then it will go through only thin body parts.

_______ is/are used in modern intensifying screens because they absorb more xrays per crystal and produce more light.

rare earth phosphors

A collimating device or collimator limits ____ of _____ or particles.

rays of light

If a worker exceeds the allowable dose of radiation exposure:

the employer shall investigate the cause and report the findings

Frequency is

the number of waveforms that strike an object during a given time period.

What are collimators?

the source of the xray beam *the act of coning down refers to increasing the collimation and lowering the size of the x-ray field.

Tissue effected by radiation exposure

tissues include the skin, lymphatics, hematopoietic tissue, breast tissue, the thyroid, bone growth centers, eyes, and germinal epithelium or gonads.

What are x-ray cassettes?

used to hold the x-ray film.

Cassettes are not designed to be

waterproof

What is scatter radiation? What helps with this?

x-rays that have been deflected from an object and have changed paths -the x-ray tube is housed in a lead tube. This prevents the unused x-rays from exiting the immediate area of the tube.

When radiation comes in contact with living cells, four effects occur on those cells:

• Radiation can pass through the cell with no effect • Radiation damages cells to a degree that they are repairable • Radiation damages cells to a degree that they are not repairable • Radiation kills the cells

Key points

• The long-term effects of radiation on the body can be somatic or genetic in nature. • Radiation exposure is described in terms of the sievert (Sv) with 1 sievert (Sv) equal to 100 REM. • Maximum permissible occupational exposure to radiation is 5 REMs annually. • ALARA is an acronym that designates an exposure dose "as low as reasonably achievable." • Radiation exposure can come from the primary beam, scatter radiation, and X-ray tube head. • The intensity of the X-ray beam decreases to 1⁄4 if the distance between the beam and the staff member is doubled