Rad Oncol (Anderson) Flashcards
electrons, neutrons, protons, alpha particles and heavy charged ions are all what kind of radiation?
particulate
x-rays (from outside the nucleus) and gamma rays (from inside the nucleus) are the two forms of what kind of radiation?
eletromagnetic (photons)
Which of these is a property of electrons? A. large and dense B. positively charged C. accelerated by a cyclotron D. also called beta particles E. have very little exit dose
D. Electrons are also called beta particles. All of the other properties are those of protons.
particle produced when a charged particle is accelerated and slammed against a target material; may cause extensive damage to tissues
neutrons
these particles that are the nuclei of helium atoms and are emitted from radon gas get trapped in the lining of the lungs, which is why radon gas exposure tends to produce lung cancer
alpha
these are positively charged nuclei of elements such as carbon, neon, argon, and iron that are accelerated in a synchrotron (giant machine in japan)
heavy charged particles
what is the difference between x-rays and gamma rays?
they differ in the way they are produced. xrays are produced outside of the nucleus when electrons accelerate and crash. gamma rays are produced inside the nucleus of an atom and are emitted via radioactive decay.
____ and ____ are indirectly ionizing, meaning that they do not produce chemical or biological damage themselves, but when they are absorbed in a medium they give up their energy to produce fast-moving charged particles that will.
neutrons and photons
what type of particle is useful in the treatment of superficial cancers and why?
electrons - this prevents deeper unncecessary damage, as electrons are able to penetrate through something only about the thickness of a sheet of plywood
the most deeply penetrating radiation that takes several feet of concrete to stop
gamma rays, x rays, neutrons
how do photons cause damage to a DNA molecule?
lndirectly, through their interaction with water molecules and formation of OH radicals
Because DNA repair enzymes are ramped up and a complimentary copy of DNA is available as a template, this phase is considered a “radio-resistant phase”
S-phase
this phase is considered the most “radio-sensitive” phase, because there is no time for repair prior to attempting cell division
G2/M phase
why are tumor cells more sensitive to radiation than normal cells?
mutated tumor cells can’t repair damage as easily as normal tissue cells
these two types of chromosomal abberations occur prior to replicaiton in S-phase, and result in portions of DNA being lost
dicentric chromosome and rings
this type of chromosomal abberation occurs after replication, when an anaphase bridge prevents separation
dicentric chromatid
type of death that is the dominant mechanism following irradiation
mitotic death (cells die attempting to divide because of damaged chromosomes)
which of these is NOT one of the “four Rs”, describing the benefits of radiation therapy?
A. Reassortment of cells within the cycle
B. Reoxygenation
C. Repair of sublethal damage
D. Repopulation
E. Redox reactions
E
which of these statements about the reoxygenation of tumor cells is FALSE?
A. as a tumor shrinks, its percentage of aerated cells remains relatively constant (~15%)
B. different tumor types reoxygenate at different rates
C. scheduling at least 24 hours between radiation treatments allows tumor cells to reoxygenate in between treatment
D. aerated cells are more sensitive to radiation than hypoxic cells
E. aerated cells form a rind around hypoxic cells
A. It is the % of hypoxic cells that remains relatively constant, and makes up ~15% of the tumor.
in terms of biological effects of different types of radiation, ____ result in protons that leave large tracks of irreparable damage while _____ interact with electrons and are far less damaging.
neutrons; x-rays
True or false: an advantage of 3D conformal therapy over IMRT is that it uses inverse planning to generate tightly contoured beams for optimal dose coverage.
False. This is an advantage of IMRT over 3D conformal therapy.
Which of the following is TRUE of hypofractionated radiation therapy?
A. Late effects to normal tissues are not as dramatic
B. It is given in smaller doses
C. It is more effective for radiation-resistant tumors
D. Sometimes requires more treatments per week
E. Conventional dose is
C. Advantages of this therapy are that it can be performed in fewer treatments per week, making it less of a time commitment, and it is more effective against radiation-resistant tumors. Drawbacks include larger doses per treatment (>2 gY) and worse late effects on normal tissue.
_____ is used to line up internal markers of the patient to ensure direct delivery of radiation.
IGRT (image guided radiation therapy)
uses a small wave of photon energy to delivers information about bony versus soft tissue anatomy, to ensure proper alignment for therapy
conebeam CT
highly targeted, highly precise technique designed to treat gross tumors only with a hypofractionated (high dose) course
stereotactic radiotherapy
_____ means that the radiation source is placed right next to or inside the tissue under treatment
brachytherapy
True or false: one advantage of proton therapy over photon therapy is that protons are able to be prescribed to highly specific location with very little exit dose, whereas photons will keep interacting with tissues regardless of depth assigned
True
