HPS 420 Exam 1 Questions With
Accurate Answers
Protons - ANSWER positively charged particles found in the nucleus. it represents the
atomic number and tells us what the element is.
Electrons - ANSWER negatively charged particles found outside the nucleus. they are
the smallest continuitent
Is the binding energy of an electron greater in the inner shell or outer shell? - ANSWER
inner shell
Neutrons - ANSWER neutrally charged particles found in the nucleus
Low LET - ANSWER x-rays and gamma rays (sparsely ionizing)
High LET - ANSWER Alpha particles, neutrons, protons (densely ionizing)
How are atoms and ions different? - ANSWER Ions are atoms that have a non-zero net
charge due to their loss or gain of an electron. Atoms have no net charge.
Indirectly ionizing radiation - ANSWER Does not directly produce any chemical or
biological damage themselves but they produce fast moving charged particles when
they interact with the material. The secondary particles are what goes on to cause
biological damages.
Directly ionizing radiation - ANSWER all charged particles; can directly disrupt the
atomic structure of any material through which they pass causing chemical or biological
damages.
Directly ionizing radiation- particulate - ANSWER electrons, protons, alpha particles,
heavy charged particles
Directly ionizing ration- electromagnetic - ANSWER None
Indirectly Ionizing Radiation- Particulate - ANSWER Neutrons
Indirectly Ionizing Radiation- electromagnetic - ANSWER x-rays and gamma rays
What type of ionization can ALL particles cause? - ANSWER direct ionization
Particulate radiation - ANSWER alpha particles, beta particles, neutrons, protons
Electromagnetic radiation - ANSWER UV rays, radiowaves, microwaves, infrared rays,
gamma rays, x-rays
, Excitation - ANSWER the raising of an electron to a higher energy level without ejecting
the electron. Excitation is temporary and the electron will go back to its normal state.
Ionization - ANSWER When there is enough energy for an electron to be ejected from an
atom resulting in an ion pair of one freed electron and the remaining atom (+)
Direct Action - ANSWER Ionizing radiation or secondary particles interacts with critical
targets (DNA) in the cells. The atoms of the target are ionized or excited initiating the
chain of events leading to biological damage
Indirect action - ANSWER Ionizing radiation or secondary particles interacts with other
atoms or molecules (typically water) int he cell to produce FREE RADICALS that are able
to diffuse far enough to reach and damage the critical targets
Why are neutrons indirectly ionizing but produces direct actions? - ANSWER Since they
don't have a charge, they cannot interact with the atom (indirectly ionizing radiation) but
they are direct action because the secondary particle after ionization interacts with the
DNA directly
How do x-rays and neutrons differ? - ANSWER Neutrons interact with just the nuclei
whereas photons and electrons interact with electrons.
Photoelectric Effect - ANSWER A photon interacts with inner shell electrons. The
photon's energy is completely absorbed by an electron and the electron then gets
ejected from the atom. The energy range PE happens in is 1-10 keV (in diagnostic
range); as photon energy increases the probability of PE decreases
Compton Scattering - ANSWER A photon interacts with outer shell electrons. The
photon's energy is NOT completely absorbed and it gets scattered at a different
wavelength. The electron that it interacted with gets ejected. The energy range
compton scattering happens in is 10 keV-10 MeV. (in diagnostic range)
Pair Production - ANSWER A photon interacts with the nucleus to which both an
electron and a positron is produced. The photon does not survive this interaction, all of
its energy is absorbed. Pair production dominates at high photon energy (> 1.022 MeV,
not in diagnostic range)
What is the smallest amount of energy needed to eject an electron? - ANSWER Whatever
the binding energy is
Equation for kinetic energy - ANSWER KE= hv-Eb (hv= energy of incident photon
Eb=binding electron)
Radiation with a long wavelength has a __________ frequency? - ANSWER smaller
Absorbed dose - ANSWER amount of energy deposited per unit mass
Absorbed dose equation - ANSWER D=E/m
Accurate Answers
Protons - ANSWER positively charged particles found in the nucleus. it represents the
atomic number and tells us what the element is.
Electrons - ANSWER negatively charged particles found outside the nucleus. they are
the smallest continuitent
Is the binding energy of an electron greater in the inner shell or outer shell? - ANSWER
inner shell
Neutrons - ANSWER neutrally charged particles found in the nucleus
Low LET - ANSWER x-rays and gamma rays (sparsely ionizing)
High LET - ANSWER Alpha particles, neutrons, protons (densely ionizing)
How are atoms and ions different? - ANSWER Ions are atoms that have a non-zero net
charge due to their loss or gain of an electron. Atoms have no net charge.
Indirectly ionizing radiation - ANSWER Does not directly produce any chemical or
biological damage themselves but they produce fast moving charged particles when
they interact with the material. The secondary particles are what goes on to cause
biological damages.
Directly ionizing radiation - ANSWER all charged particles; can directly disrupt the
atomic structure of any material through which they pass causing chemical or biological
damages.
Directly ionizing radiation- particulate - ANSWER electrons, protons, alpha particles,
heavy charged particles
Directly ionizing ration- electromagnetic - ANSWER None
Indirectly Ionizing Radiation- Particulate - ANSWER Neutrons
Indirectly Ionizing Radiation- electromagnetic - ANSWER x-rays and gamma rays
What type of ionization can ALL particles cause? - ANSWER direct ionization
Particulate radiation - ANSWER alpha particles, beta particles, neutrons, protons
Electromagnetic radiation - ANSWER UV rays, radiowaves, microwaves, infrared rays,
gamma rays, x-rays
, Excitation - ANSWER the raising of an electron to a higher energy level without ejecting
the electron. Excitation is temporary and the electron will go back to its normal state.
Ionization - ANSWER When there is enough energy for an electron to be ejected from an
atom resulting in an ion pair of one freed electron and the remaining atom (+)
Direct Action - ANSWER Ionizing radiation or secondary particles interacts with critical
targets (DNA) in the cells. The atoms of the target are ionized or excited initiating the
chain of events leading to biological damage
Indirect action - ANSWER Ionizing radiation or secondary particles interacts with other
atoms or molecules (typically water) int he cell to produce FREE RADICALS that are able
to diffuse far enough to reach and damage the critical targets
Why are neutrons indirectly ionizing but produces direct actions? - ANSWER Since they
don't have a charge, they cannot interact with the atom (indirectly ionizing radiation) but
they are direct action because the secondary particle after ionization interacts with the
DNA directly
How do x-rays and neutrons differ? - ANSWER Neutrons interact with just the nuclei
whereas photons and electrons interact with electrons.
Photoelectric Effect - ANSWER A photon interacts with inner shell electrons. The
photon's energy is completely absorbed by an electron and the electron then gets
ejected from the atom. The energy range PE happens in is 1-10 keV (in diagnostic
range); as photon energy increases the probability of PE decreases
Compton Scattering - ANSWER A photon interacts with outer shell electrons. The
photon's energy is NOT completely absorbed and it gets scattered at a different
wavelength. The electron that it interacted with gets ejected. The energy range
compton scattering happens in is 10 keV-10 MeV. (in diagnostic range)
Pair Production - ANSWER A photon interacts with the nucleus to which both an
electron and a positron is produced. The photon does not survive this interaction, all of
its energy is absorbed. Pair production dominates at high photon energy (> 1.022 MeV,
not in diagnostic range)
What is the smallest amount of energy needed to eject an electron? - ANSWER Whatever
the binding energy is
Equation for kinetic energy - ANSWER KE= hv-Eb (hv= energy of incident photon
Eb=binding electron)
Radiation with a long wavelength has a __________ frequency? - ANSWER smaller
Absorbed dose - ANSWER amount of energy deposited per unit mass
Absorbed dose equation - ANSWER D=E/m
