Radiation safety- part 1, chapter 2- Laura nappi

Radiation can be emitted in the form of

particles, electromagnetic radiation, or both

Emitted radiation includes

alpha, beta, and gamma rays

Alpha particles are ___ charges

positively

Beta particles are ___ charges

negatively

Gamma rays have ____ charge

No

____________ occurs as the source emits radiation in attempt to become stable

Radioactive decay

Elements with higher atomic number are more likely to be

radioactive

____ is the radioactive sources rate of decay

Activity

The SI unit of activity is the

Becquerel (Bq)

1 Becquerel (Bq) = ___ dps

1 dps

1dps = ____ Curie(ci)

2.70X 10^ -11 CI

What is formula for activity?

A= Ao (0.5) ^ t/T1/2

__________ of a radioactive source describes the duration of time it takes for the activity to decay to half the original value

Half- Life (T 1/2)

______ of a radioactive source describes the average lifetime decay

Mean life (Ta)

Radioactive materials can be used for diagnostic tests like

nuclear medicine

What is example of nuclear medicine radioactive material

Technetium-99

What are some examples of therapeutic radioactive materials?

Iodine-125, Palladium- 103, iridium- 192, colbolt-60, Strontium- 90

_______ is a "short-distance therapy" that uses radioactive materials to treat certain cancers internally

Brachytherapy

Brachytherapy sources typically have lower energies that have a

rapid- fall off

Brachytherapy is common used for treatments of the

Uterus, cervix, lung, prostate, and breast

There are different types of brachytherapy applications that can be used depending on the

size and location of the tumor

__________ are plastic molds that conform to patients skin surface with source placed on the outer surface mold

External applicators

External applicators, brachy, are used to treat

tumor beds, skin surfaces, or mucosal surfaces

_____ is a brachy applicator with radioactive source placed within body cavity

intracavitary

Intracavitary applicators are use to treat

GYN tumors

Vaginal cylinders, tandem and ovoid, and fletcher-suit applicator are what type of brachytherapy appicators

Intracavitary

_____ is a type of brachy where the radioactive source is placed with needles, wire, or seeds directly into malignant tissues

interstitial

The most common radioisotopes used in brachytherapy are

sealed sources

What does sealed sources mean?

that they are covered by metal casing

sources that are used for low dose rate brachytherapy (LDR) treat

40-200 cgy/hr

Sources that are used for high dose rate brachytherapy (HDR) treat

12Gy/hr or .2 cgy/hr

_____ was the original radioactive isotope, which helped start brachytherap

Radium (ra-226)

Half life= 2.67 days

Ex use: liver caner and lymphoma treatment

Exampling which radioactive source:

Yttrium (y-90)

Half life= 2.7 days

Ex of use= Permanent implant (seeds) for prostate cancer treatment

Exampling which radioactive source:

Gold (Au-198

Half life= 8 days

Ex of use= thyroid cancer treatment

Exampling which radioactive source:

Iodine (I-131)

Half life= 17 days

Ex of use= permanent implants for prostate cancer treatment

Exampling which radioactive source:

Palladium (Pd- 103)

Half life= 50.5 days

Ex of use= treats pain caused by bone mets

Exampling which radioactive source:

Strontium (sr- 89)

Half life= 59.4 days

Ex of use= permanent implants for the treatment of prostate cancer

Exampling which radioactive source:

Iodine (I-125)

Half life= 73.8 Days

Ex of use= HDR treatments and made of nylon ribbons with seeds

Exampling which radioactive source:

Iridium (Ir-192)

Half life= 5.26 Years

Ex of use= External beam treatments

Exampling which radioactive source:

Cobalt (Co-60)

Half life= 28 years

Ex of use= treats cancers in the eye (pterygium)

Exampling which radioactive source:

Strontium ( Sr-90)

Half life= 30 years

Ex of use= Brachytherapy for cancers of the cervix or uterus

Exampling which radioactive source:

Cesium ( C-137)

Half life= 1,622 years

Ex of use= original radioactive isotope

Exampling which radioactive source:

Radium (Ra- 226)

_____ radiation is man-made radiation created within an x-ray tube that consists of a cathode and an anode within a class envelope

photon

Photons (x-rays) are formed when a high voltage is applied between the

cathode and anode

The voltage of proton is supplied by a

generator

1 kilovolt = ___ volts

1000

1 megavolt= ___ volts

1,000,000

1 megavolt= ____ kilovolts

1,000

_____ is a negatively charged electrode with a tungsten filament that releases electrons when heated ( aka thermionic emission)

Cathode

Tungsten has a Z number of ___ and melting point of ___

Z = 74

Melting point= 3370 Celsius

____ is a positively charged electrode made of tungsten and is also known as the target

anode

Rotating anodes allow for more ______

heat dissipation

Hooded anodes prevent unwated

secondary electrons

Targets in megavoltage therapy machines are known as

transmission targets

In a linear accelerator, there is a waveguide between the electron gun and target to increase

electron energies

Therapy x-ray photons have energies from

50 keV to 25 MeV

Common beam energies for linear accelerators range from

4MV to 25 MV

Orthovoltage energies range from

150-500 kV

Superficial therapy energies range from

50-150 Kv

When electrons interact with the target, they either produce

bremsstrahlung, x-rays or characteristic x-rays

______ is an electron interaction that occurs near the nucleus

Bremsstralung

In bremsstrahlung the electron does what?

Slows down as it approaches the nucleus and then changes uts direction

______ is where the incoming electron interacts with an inner shell electron, causing the inner shell electron to be ejected

Characteristic

With characteristic x-rays an outer shell fills the

new vacancy

Characteristic X-rays only occur in

Diagnostic Radiograph NOT radiation therapy

______ beam radiotherapy includes high-energy charged, particles, such as protons, alpha particles, and carbon ions

particle

What is a cyclotron?

Charged particle accelerator

What is a cyclotron used for

Used in proton herapy to speed up protons

The common benefit of protons is the dose distribution because of _____

bragg peak

Bragg peak is the dose curve of a proton beam. It starts off low at beginning but then rapidly rises toward the ends of the path and then.....

abruptly falls to zero

The depth of Bragg peak can be adjusted based on the

beam energy

X-ray photons are electromagnetic energy and travel in...

waves

Characteristic of a wave include

frequency, wavelength, velocity, and amplitude

___ is the number of waves that pass a given point in one second.

Frequency

___ is the measured distance between two specific points of the wave

wavelength

What an example of a wavelength?

Peak to peak or valley to valley

What unit is wavelength measured in?

meters

___ is how fast the wave is traveling (speed)

velocity

X-rays travel at the speed of

light in a vacuum

What is the SI unit for the speed of light?

3 X 10^8 m/sec

_____ us half the distance from one crest to one valley of the wave

Amplitude

____ have both wave and particle characteristics

photons

Photons have no

mass or charge and low LET

As the radiation beam travels through matter, it will diverge and decrease in intensity because of the

inverse square effect

The beam decreases in intensity because it is either absorbed or scatter in a different.......

direction than it travels through matter

The beam intensity will decrease more as the thickness of attenuating material _____

increases

3 multiple choice options

The radiation beam intensity (dose) with decrease with increasing distance due to the

beams divergence

____ is inversely proportional to square of distance from source

beam intensity

IF distance increases by two, then the intensity

decreases by 4

IF distance decreases by two, then intensity

increases by 4

PDD equations use the inverse sqaure law when implementing

Mayneord F factor

Beam quality describes the beams ability to

penetrate

Different types of radiation have different beam qualities and can produce different ____

amounts of response

Quality factor (QF) are assigned to describe the type of

Radiation

What is the quality factor of X-rays, gamma rays, beta particles, electrons

1

What is the quality factor of protons

2

What is the quality factor of neutrons

3 to 10

What is the quality factor of heavy particles (alpha particles)

20

___ interaction with electrons can produce coherent or elastic scattering, photoelectric effect and Compton scattering

Photons

3 multiple choice options