Rad safety registry review YouTube

Source of electrons

At the filament of the cathode (negative side)

The filament of the cathode consists of

small coil of tungsten wire

What provides the electron source for the xray production

Space charge/ electron cloud

If you increase mA, you ______ the filament current

increase filament current (this leads to increase of xray photons)

______ forces the electrons across the tube giving them kinetic energy

kVp

(the higher the kVp the more energy the accelerated electrons will have)

Houses the filament wires

focusing cup

Focusing cup is made up of

molybdenum or nickle

the focusing cup holds the released electrons around the filament wires in a tiny cloud called a _______ until the exposure switch is engaged

space charge

To convert the electrons kinetic energy the accelerating electrons must be

slowed down or stopped (deceleration)

When do the electrons decelerated?

when they strike the anode

The anode is a ______ disk

tungsten (rhenium)

The anode has a high ______ and a high _____

atomic number (74) and a high melting point

There are two interactions that occur at the target (anode)

Bremsstrahlung and Charachteristic

Bremsstrahlung is also known as

braking radiation

Bremmstrahlung radiation is ___% of all xray production

90%

Bremsstrahlung interactions is 100% of xray production below _____ kVp

70 kVp

K shell binding energy of tungsten

69.5 or 70 keV (characteristic radiation)

Number of times per second the electric and magnetic fields generate themselves

frequency

The higher the frequency the ______ the energy

higher

Unit of frequency

Hertz (Hz)

Distance between two successive peaks (tops of the waves)

wavelength

wavelength and frequency relationship

inversely related

Refers to the energy of the xray photons

quality, kVp, penetration

refers to the number of xray photons

quantity , mAs

Refers to the xrays that are produced by the xray tube and strike the patient

primary beam (either Bremsstrahlung or characteristic)

The remaining beam after it leaves (exits) the patient

remnant beam

Remnant beam is made up of

primary and secondary radiation

The intensity of radiation is inversely proportional to the square of the distance between the xray tube and the image receptor

inverse square law

when distance is doubled, what happens to intensity?

it is decreased by 4 times

when distance is cut in half, what happens to the intensity?

it is increased by four times

What three xray interactions with matter occur in diagnostic?

-compton

-PE absorption

-coherent (classical) scatter

Most common interaction with matter and is the least desirable

Compton effect

Compton effect: energy partially absorbed by loosely bound ____ shell electron

outer

What type of interaction is Compton effect?

ionization interaction

Compton effect produces ______ photon (low energy) going in different direction

scatter

Compton effect is the source of most ______ exposure

occupational

Compton effect is the source of most _____ seen on the IR

fog

Photoelectric effect: the photon energy equals the _____ energy

binding

Photoelectric effect: _____ shell electron is knocked out of orbit (ionization)

inner

Photoelectric effect is the source of most ____ exposure

patient

The reduction in the intensity of an x-ray beam as it passes through material is termed

attenuation

The higher the _____ of the body part the greater the attenuation of the xray beam and the greater the biological effect

atomic number

Attenuation has what relationship with receptor exposure ?

indirect relationship

Radiation in air

exposure and air kerma

Radiation in tissue

-absorbed dose

-equivalent dose

-effective dose

Electrons are represented by a Sine wave or a straight line?

straight line

Photons are represented as a sine wave or a straight line?

sine wave

NOTE

If the diagram of an interaction starts as an electron then it is a tube interaction.

If the diagram of an interaction starts with a photon then it is a patient interaction.

Refers to the xray beam prior to any interaction with the patient, grid, table, or image receptor

Primary beam

The beam that interacts with the detector is termed

exit beam

Direct result of Compton effect and contributes to most staff radiation dose

Scatter radiation

Leakage radiation comes from

xray tube housing

Leakage radiation is limited to a maximum of

1 mGya/hr at 1 meter

6 feet = ___ meters

1.8 meter

Exposure is measure by multiplying what

exposure rate X exposure time

If you increase kVp/ quality of the xray beam then scatter will _____

increase

If you increase the FOV then scatter will _______

increase

If you increase collimation then scatter will ________

decrease

If you increase pt size then scatter will ______

increase

Exposure switch on portable must be at least ___ ft

6 ft (1.8 or 2m)

Exposure switch on portable xray must be what type?

dead man type

What protective shielding is 0.5 mm Pb?

aprons and thyroid shields

What protective shielding is 0.35 mm Pb?

glasses

How often should lead aprons be evaluated to determine if cracks or holes are present?

annually

what protective shielding is 0.25 mm Pb?

gloves, Bucky slot cover, and protective curtain

___mm Pb is recommended for fluoroscopy

0.5

Anywhere where the primary beam could be directed

primary barrier

examples of primary barrier

wall behind the wall Bucky and the floor below the table Bucky

what must the height be for the primary barrier?

7 feet/ 2.1 m

Primary barrier must contain ____ inch pB

1/16 or 4 inches of brick/ concrete

Located wherever leakage or scatter radiation may strike

secondary barrier

Examples of secondary barriers

ceiling, doors to xray room, xray control booth

Secondary barrier must contain ____ inch pB

1/32

What determines the barrier thickness?

1. Distance

2. Who Occupies that area

3. mA min per week (Type of exams) / workload

4. Amount of time in use/ Use factor

uncontrolled areas should be shielded to ensure an effective dose limit to the general public of ___uSv (micro sieverts) per week

20

Controlled areas (occupied by persons trained in radiation safety) should be shielded to keep exposure under ___ mSv per week

1

amount of time the beam is on and directed at a particular barrier

use factor

occupational workers that may exceed ___% of the annual limit must wear dosimeters

10%

Dosimetry devices used to measure the output of the xray tube

ionization chambers

Immediate environmental reading most commonly used to detect contamination

Geiger conter

Immediate personal readout

pocket ionization chamber

work by converting xray energy into visible light

Scintillators

Annual whole body effective dose limits (stochastic effects) for occupation workers

50 mSv

Annual dose for lens of the eye for occupational workers

150 mSv

Cumulative effective limit dose/ lifetime for occupational worker

10 mSv X age

General population (infrequent) exposure annual effective dose limit

5 mSv or 10% of occupation dose

Public exposure effective dose limit (continuous) annually

1 mSv

Dose limit for lens, skin and extremities for public exposure annually

50 mSv

Embryo/ fetus total dose equivalent limit annually

5 mSv

Embryo/ fetus total dose equivalent limit in a month

0.5 mSv

Student radiographer annual equivalent dose limit

1mSv

Where should a radiation monitoring device be worn for routine radiography?

worn on the collar outside the apron at chest level

where should pregnant technologist where additional dosimeter?

at waist level under the apron

-heated and releases light in proportion to exposure

-no permanent record

-not exchanged bu every 90 days

-contains lithium fluoride

TLD

-Immediate reading

-false positive/ flase negative concerns

-NO permanent record of dose

pocket dosimeter

-Aluminum oxide is exposed to a laser and emits visible light in proportion to radiation exposure

-filter allow determination of deep, shallow and eye exposure

-allows permanent record of dose

OSLD

1 mSv= ___ mrem

100

50 mSv= ___ mrem

5000

The unit of absorbed dose

Gy

Xray photon with matter and the transference of part of the photons energy to matter

scatter