screener Flashcards
what are the 3 acute radiation syndromes in humans
- Cerebrovascular/Neurological syndrome (>20 Gy, shock/death, headache, weakness)
- Gastrointestinal syndrome (~10 Gy, death in 3-10 days, nausea)
- Hematopoietic syndrome (2.5-5 Gy, bleeding, infection, anemia)
what are some examples of functional endpoints
-breathing rate
-paralysis
-bladder function
-tear production
-lethality
what are some commonly used SPECT isotopes
99mTc
67Ga
201Tl
131I
what is single-photon emission computed tomography (SPECT)
uses gamma cameras to detect photons from injected radiotracers in the body
-provides 2-3D image based on distribution of radiotracers
-low resolution
-information on blood flow and metabolism
what kind of information does computed tomography (CT) give us
shows the distribution of attenuation coefficients in the body
-measures projections in different directions
what kind of information does magnetic resonance imaging provide (MRI)
shows spacial distribution of proton density in the body
what are the phases of acure radiation syndrome
- prodromal syndrome (loss of appetite, fatigue)
- latent phase (length decreased w increased dose)
- illness
- recovery or death
define flash RT
single ultra high dose rate (>40 Gy/s)
-too short for reoxygenation, repopulation, redistribution
-anti-tumor effects with less protective functions and less toxicity to normal cells
what are some examples of some isotopes used for RIT and what particles do they emit
beta: (131I, 90Y, 177Lu)
alpha: (213Bi, 225Ac, 227Th, 223Ra, 211At, 212Pb)
what are some considerations when choosing therapeutic isotopes for radio-immuno therapies
-physical half-life
-availability
-emission type
-photon emission (imaging)
-stability with conjugate
define radio-immuno therapy
administration of a radionuclide conjugated to an antibody for therapeutic intent
limitations: toxicity, tumor penetration
define brachytherapy
implanting radioactive sources in/close to tumor
define neutron capture therapy
non-invasive radiation therapy for treating localized and distributed malignant tumors
1. non radioactive isotope with high thermal n capture xs
2. radiate with epithermal n
3. isotope captures and decays next to tumor
what are the different types of x-ray production machines
- orthovoltage
- linacs
- co sources
advantages/disadvantages and common uses of CT
advantages: fast, detailed, 3D image
disadvantages: requires radiation
uses: detecting solid tumors and other issues in abdomen/chest
advantages/disadvantages and common uses of MRI
advantages: detailed, no radiation
disadvantages: expensive, uncomfortable, slow
uses: brain issues and soft tissue injury
advantages/disadvantages and common uses of ultrasound
advantages: cheap, no radiation
disadvantages: low image quality
uses: fetal and children
advantages/disadvantages and common uses of x-ray
advantages: fast, cheap, low dose
disadvantages: uses radiation, less detail, 2D
uses: broken bones, intestinal issues
what kind of information is provided with an ultrasound
intensity of ultrasonic waves and its signal reflected in the body
compare CT and SPECT
CT: transmission, measures linear attenuation coefficients, body structure information, fast
SPECT: emission, measures radionuclide distribution, biological function/metabolism, long
what is a radiograph
diagnostic x-rays attenuated in the body
describe positron emission tomography (PET)
works by the simultaneous detection of annihilation photons that are produced during positron emission
-requires energy discrimination and coincidence timing
-not great resolution
what is dual modality imaging
structural: CT/MRI
functional: SPECT/PET
how is 99mTc produced
decay of mo99
