physics semester 1 (ALL EXAMS)

Which of the four natural forces is responsible for holding the protons and neutrons together to form the nucleus

strong force

The Newton is the SI unit of

force

As the wavelength of an X-ray photon increases, frequency

decreases

As the wavelength of a photon decreases, energy

increases

As the frequency of a photon increases, energy

increases

In radiation therapy, biologic damage occurs when X-ray or electron beams impact energy to matter, causing

ionization

The octet rule states that no more than ______ electrons are permitted in the outermost shell of an atom

8

Which forms of radiation are considered high LET radiation

Alpha, protons, neutrons

For an electron to be ejected from an orbital shell within an atom, energy must be

applied

Energy of motion is termed

kinetic energy

What particle contains two protons and two neutrons, thus resembling an atom of helium

alpha

The model of the atom, which is recognized today, was introduced by

Bohr

The energy that holds an electron in its orbital shell is referred to as a

binding energy

The energy that holds an electron in its orbital shell is overcome by the

addition of energy

The energy that holds an electron in its orbital shell is related to the force of attraction between the _______ and the ____ electron shells

nucleus, orbital

A neutral atom that loses an electron has an overall _ charge

positive

.511 MeV is the resting energy of an

electron

Of the three fundamental particles of an atom, which one possesses the greatest mass

neutrons

The _ of an element is equal to the number of protons and neutrons in the nucleus of an atom

Atomic mass number

The most commonly used unit of energy used to refer to a radiation therapy photon beam is

mega-electron volt

In an ______ collision, some of the kinetic energy is lost during the collision and can reappear as a different form of energy

inelastic

Gamma rays possess the same properties of x-ray photons, however, they differ in their

origin

Calculate the maximum number of electrons in the shell of an atom, given that the M shell is not a valence shell of an atom

18

Which forms of radiation are directly ionizing

alpha, beta, protons

1.6021×10(-19) joule =____eV

1

The _________ number is the number of electrons in the outermost orbital shell of an atom which provides information about the atom, chemical activity or behavior

valence

The speed of light is

3 x 10(8) m/s

Which form of radiation is the product of interactions between high-speed electrons and nuclei of higher atomic number of atoms within the target of the radiation therapy treatment unit

Bremsstrahlung radiation

The SI unit of energy is

joule

The amount by which the mass of an atomic nucleus is less than the sum of the masses of its constituent particles is referred to as

mass deficit

Atoms having the same number of neutrons, but different number of protons

isotone

Atoms are the same except for their nuclear energy states

isomere

Atoms having the same number of protons, but different number of neutrons

isotope

The majority of the x-ray photons and the radiation therapy beam are

Bremsstrahlung x-ray

Which forms of radiation are categorized as electromagnetic radiation

X-rays and gamma rays

The energy deposited into a medium per unit length of travel by ionizing radiation as it passes through the medium is termed

LET

The force which holds electrons and protons together inside an atom is termed

electromagnetic force

A patient's treatment is planned to deliver 200cGy from the anterior field with an SSD of 90 cm. By accident, for one fraction, the therapist used an SSD of 91 cm. What fraction dose was delivered as a result of the error

196cGy

A beam that is described as homogeneous is one in which the photons of the beam have

same energy

The addition or removal of an electron from an orbital shell of an atom is termed

ionization

As atomic number increases, the probability of a photoelectric effect

increases

Percentage of beam transmission on beam passes through a 4 cm block, with a half value layer thickness of 2 cm

25%

The inverse square law states that the intensity of radiation is ________ proportional to the square of the distance between the source of radiation and the point measurement

inversely

The exposure rate for a monoenergetic source of radiation is 80cGy/hr. How many half value layers are required to shield the source to a rate of 10cGy/hr

3

Influences the probability of Compton scatter interaction

Energy of the incoming photon; Number of electrons within the absorbing material (electron density)

A homogeneity coefficient closer to a value of 1.0 indicates that the beam is more

homogeneous

A 5cm attenuator is placed within the path of an x-ray being produced. If the half value layer for the beam is 2 cm, what is the percentage of beam transmission through the attenuator?

17.7%

Interaction involving the conversion of energy to matter and then back to energy

pair production

Interaction who's probability increases with increased electron density

compton scatter

Interaction requires the incoming photon to possess an energy of 1.02 MEV or greater

pair production

Interaction involving an incoming photon that gives up some of its energy to a loosely bound electron causing ionization

compton scatter

Interaction involving a low energy photon that is absorbed by an electron of an atom and is then remitted in a new direction with the same energy it had originally

coherent scatter

Interaction which is responsible for causing components of the linear accelerator to become activated or radioactive

photodisintegration

Interaction involving an incoming photon, giving up all of its energy to an inner shell electron causing ionization

photoelectric effect

Interaction that is independent of the atomic number of the absorbing material

compton scatter

This refers to the phenomenon of the photoelectric effect, where the energy of the incoming photon becomes equal to or just slightly greater than the binding energy of the electron shells, causing an increase in absorption

absorption edge

A photon beam that traverses matter, unaffected as described as being

transmitted

At a distance of 8 feet from a source of radiation, your survey meter reads 100mR/hr. What is the radiation intensity at 1 foot from the source?

6400 mR/hr

Calculate the linear attenuation coefficient of the half value layer is 2.1 cm

.33cm(-1)

6.25% of a photon beam is transmitted through an attenuator. If the half value is 2 mm, what is the actual thickness of the attenuator?

8mm

85 MeV photon interacts with an atom by way of pair production. What is the total energy given to each particle if the energy is divided equally between each particle?

1.9MeV

A photon that is scattered 180° will have an energy of

.255 MEV or less

The linear attenuation coefficient divided by the mass density of the attenuator is termed

mass attenuation coefficient

Photoelectric effect ________ ionization

causes

Pair production _ ionization

does not cause

Compton scatter _ ionization

causes

Coherent scatter _ ionization

does not cause

During the pair production interaction, a positron comes to rest and combines with an electron giving rise to two .511 MEV photons that travel in opposite directions. This component of pair production is called.

pair annihilation

In the energy range of radiation therapy treatment delivery, the predominant interaction between a photon and matter is

compton scatter

The photoelectron, which is a product of the photoelectric effect, refers to the

ejected inner shell electron

A photon that is scattered 90° direction and travel will have a energy of

.511MeV

As an emitted characteristic photon travels away from the atom, it could interact with an orbital electron of that same atom and cause it to be ejected, termed a

Auger electron

The thickness of a material which reduces the radiation beam intensity by 50% is termed the

HVL

Attenuation results in a change of the beam's quality, but not beam quantity

false

This refers to the process that occurs as a radiation beam traverses matter in photons are gradually removed from the beam

attenuation

This refers to the removing low energy photons from a polyenergetic photon beam as it passes through matter, thus increasing the average energy of the photon beam

beam hardening

Photonuclear interactions become important starting energies of approximately

10-15MeV

What radiation is considered indirectly ionizing

neutrons, x-rays, protons, gamma ray

Attenuation is a combination of scatter and

absorption

The ratio of the initial intensity and the final intensity of a radiation beam after passing through a medium is termed

transmission

A neutral atom which loses an electron through ionization will have a _ charge

positive

Equal absorbed doses of different types of radiation produce the same biological damage

false

This refers to a condition in a high energy photon beam with the number of electrons coming to rest equals the number of electrons being set into motion

electron equilibrium

Solve for the equivalent dose of 10Gy of alpha radiation

200Sv

As photon beam energy increases, the depth of electron equilibrium

increases

A cutie pie is considered a portable ionization chamber

true

What materials are commonly used in neutron detectors to slow down the particles so they may be measured

Hydrogen and boron

The dose buildup region of a depth dose chart is defined as the region where the

Beam is building towards the peak absorbed dose

If a patient is exposed to 100cGy of electrons, what is this person's equivalent dose?

1Sv

Which radiation detection device discriminates between beta, alpha, and gamma radiation

Proportional counter

Which radiation detection device is used in the calibration of a linear accelerator

ionization chamber

Which radiation detection device is used to locate a lost brachytherapy source

Geiger Mueller counter

Which radiation detection device is used to survey of treatment console area of linear accelerator

Cutie pie survey meter

100 ergs per gram of matter best defines

1Rad

The amount of energy transferred to electrons from incoming photon best defines

Kerma

3000cGy is equivalent to _______ Gy

30

As air temperature increases, the number of ionizations per volume of air

decreases

As LET decreases, RBE

decreases

This is defined for gamma and x-ray, photon beams, is only valid for photon beams less than 3MEV, and is only valid for in air measurements

exposure

An exposure measurement of 90R is equivalent to an in air dose of

79rad