Exam 1 - Radiation Oncology Flashcards
what is radiation?
electromagnetic energy
what is ionizing radiation?
radiation with sufficient energy to detach electrons from atoms - ionizing atoms
T/F: gamma=xray=photon
true
what is the ionization ability & penetration of alpha-rays?
can ionize the atom very readily but penetrability is limited because it isn’t high energy
what is the ionization ability & penetration of beta-rays?
greater penetration than alpha-rays but less ionizing than alpha-rays
what is the ionization ability & penetration of gamma-rays?
least ionizing but most penetration
what diagnostics use gamma rays (electromagnetic radiation)?
radiographs, CT, PET-CT, & radiation therapy
what is teletherapy/tomotherapy (external beam)?
showers the patient with photons
what is brachytherapy?
radioactive isotype is placed within the patient
what is plesiotherapy?
put the probe on top of the area of interest
why can’t you be with the patients receiving radiation therapy?
megavoltage photons are used - way too dangerous
what are the diagnostic levels of energy typically used?
20-120 kVp
what is mAs?
of electrons
what is kVp?
energy of xray
what happens when you increase mAs?
increase the dose to the patient
what happens to your image if you increase kVp?
decrease the diagnostic quality
how many volts are in tomotherapy?
6 million volts
what are the 3 parts to integrated oncology?
medical, surgical, & radiation oncology
in radiation planning, what is contouring?
determining normal structure vs the target for therapy
what are the 3 components of radiation protocol?
- client goals
- dose required for adequate control for tumor type or palliation
- limited by dose tolerances of surrounding normal tissues
what tumor types are less responsive to radiation?
carcinomas & sarcomas
what tumor types are most sensitive to radiation?
round cell tumors
what are the rules of thumb for definitive radiation treatment goals as far as dosing?
10-20 fractions - low dose per fraction
high total prescription dose
typically used alone or after surgery
what are the rules of thumb for palliative radiation treatment goals as far as dosing?
2-5 fractions - higher dose per fraction
low to moderate total dose
what are the goals of definitive radiation treatment?
improve survival in OS, MST, & PFS
achieve local tumor control or locoregional control
what are the goals of palliative radiation treatment? what about secondary goals?
pain relief, improve quality of life, & improve clinical signs
secondary - slow down the progression of the tumor
what are the planning techniques for stereotactic radiation therapy?
definitive or palliative setting
when would you use stereotactic radiation therapy?
well-defined tumors
how is stereotactic radiation therapy defined?
highly conformational, heterogenous dose
high ablative dose
how many doses are needed in stereotactic radiation therapy?
1-5
what is the primary goal for pre-op radiation therapy? what is the secondary goal?
sterilize surgical margins
cytoreduction
in preoperative radiation therapy, cytoreduction depends on what?
tumor histopathology
for short course preop radiation therapy, how many fractions is the rule of thumb?
5 fractions
for short course preop radiation therapy, how many fractions is the rule of thumb?
20 fractions
T/F: in preop radiation therapy, lower doses are given compared to post-op radiation therapy
true
what are the possible risks for pre-op radiation therapy?
increased risk of surgical complications (dehiscence) & more challenging surgery
what are the benefits or pre-op radiation therapy?
well-defined tumor for radiation planning
less irradiated tissue in the patient
associated with improved osteosarcomas in human treatments
more treatment options (short course vs. long course)
why is CT used for RT planning?
electron density of tissues = HU of CT
what is the most common mode of cell death with radiation?
mitotic cell death
what is the cellular response to radiation for epithelial, mesenchymal, & round cells?
epithelial - mitotic cell death
mesenchymal - mitotic cell death
round cell - apoptosis
T/F: in radiation therapy, there are not clinically significant side effects
true
what is the exception to side effects with radiation therapy?
acute radiation sickness associated with irradiation of large volumes of the body
what is the response of sarcomas to radiation?
they are resistant
what is the response of round cells to radiation?
they are sensitive to radiation
what is the response of carcinomas to radiation?
radiation responsive
T/F: side effects from radiation only occur in the radiation field
true
what is the most common side effect of radiation?
inflammatory - transient in nature
with what kind of radiation therapy are you expecting transient side effects?
definitive radiation therapy
what is the best management of radiation therapy side effects?
anti-inflammatories - NSAIDs & steroids
prevention of self trauma!!!!
what are the chronic side effects of radiation therapy?
fibrosis
what radiation therapy type may have an increased risk for chronic side effects?
stereotactic
what happens in direct cell target in radiation therapy?
30%
single strand or double strand breaks
what happens in indirect cell target in radiation therapy?
70%
oxygen radical formation from water causes damage & damage is ‘fixed’ with oxygen
what is the compton effect?
why are photons related to the ‘skin spare’ effect?
they are indirectly ionizing
what is a gray?
1 gy = 1 j/kg
unit of absorbed dose
what is the formula for radiation protocol?
___ fractions of ___dose/fraction = total prescribed dose
fraction = treatment
what is included in the initial consult of radiation therapy?
diagnosis, staging, & treatment plan
what is included in the radiation planning of radiation therapy?
contouring & computerized planning
what is this?
multi-leaf collimator - step & shoot modulation
T/F: IMRT & IGRT are the most current historical advances seen in radiation therapy
true - tomotherapy uses IMRT & IGRT
