Lesson 1 Flashcards
This x-ray and gamma ray interaction is the predominant interaction in the diagnostic energy range with soft tissue
COMPTON SCATTERING
Occurs when the binding energy exceeds the transferred energy with resultant ejection of electron
Ionization
Maximum point of specific ionization beyond which a sharp drop is seen as the partial kinetic energy is exhausted and the charged particle is neutralized.
Bragg ionization peak
Refers to the ability to detect very subtle changes in the grayscale and distinguish them from the noise image
CONTRAST RESOLUTION
Tomographic counterpart of nuclear medicine planar imaging that provides a diagnostic functional information similar to nuclear planar examination. It uses a nuclear camera that records gamma ray emissions from the patient from a series of different angles
SPECT (Single Photon Emission Computed Tomography)
Refers to the removal of photons from a beam of x-ray or gamma rays as it passes through matter.
ATTENUATION
Defined by thickness of a material required to reduce the intensity of an x-ray or gamma ray beam to one half of its initial value
HVL (HALF VALUE LAYER)
X-ray production efficiency exposure, quality and quantity are determined by 6 major factors which are:
- Anode material
- Tube voltage
- Tube current
- Beam filtration
- Generator waveform
- Exposure time
Determines the maximum energy in the Bremsstrahlung spectrum and affects the quality of the output spectrum.
TUBE VOLTAGE (maximum energy)
The following characterizes an antiscatter grid, except
- Grid ratio
- Grid frequency
- Focal length
Most common anode target material used in mammography x-ray tubes.
MOLYBDENUM
Tube port window in mammography x-ray spectrum is made of:
BERYLLIUM
Digital radiographic imaging that addresses major problems with conventional projection imaging where there is superimposition of overlying and underlying anatomy of the breast w/ pathology.
BREAST DIGITAL TOMOSYNTHESIS
Mammography tube focal spot sizes
0.3 and 0.1 mm
This factor affects both the spatial and contrast resolution in CT imaging
RECONSTRUCTION FILTER
This CT artifact occurs when the CT voxels are large enough to encompass several types of tissue, such as bone and tissues from different organs.
PARTIAL VOLUME
T2WI have:
Long TR; Long TE
T1WI sequence
TE short, TR short, fat:bright
This sequence detects alterations in the random (Brownian) motion of water molecules within tissues, measures diffusion and is used in detection of acute cerebral ischemia.
DWI
MR artifact is a result of the mismapping of anatomy that lies outside of the field of view but within the slice volume. The anatomy is usually displaced to the opposite side of the image.
Wraparound artifacts
This sequence reduces CSF signal and other water-bound anatomy in the MR image by using T1 selected at or near the bounce point of CSF to permit better eval of surrounding anatomy.
FLAIR
Beam property where the sounds have a diverging profile
Fraunhofer zone
Type of ultrasound interaction referring to the loss of intensity of the ultrasound beam from absorption and scattering in the medium.
ATTENUATION
Distance between any two point that repeat on the sinusoidal wave of pressure amplitude.
WAVELENGTH
This artifact arises from the multiple echoes generated between two closely spaced interfaces reflecting ultrasound energy back and forth during the acquisition of the signal and before the next pulse.
REVERBERATION
Greatest probability of malformation when radiation is received in peak differentiation occurs in which stage of gestational period.
ORGANOGENESIS
Most commonly encountered tissue reaction (deterministic effect) following high dose image guided interventional procedures
SKIN DAMAGE
Limit of exposure dose for occupational exposure of workers over the age of 18
Effective dose (ED) of 20mSv per year, over 5 consecutive years
TRUE OR FALSE
A “supervised” area is any area in which specific protection measures and safety provision are required for controlling normal exposures and limiting/preventing extent of potential exposures.
FALSE
(Controlled area)
Based on J. Bergonie and L. Tribondeau, cell radiosensitivity is affected by 3 factors, which are:
MITOTIC RATE
DEGREE OF DIFFERENTIATION
STAGE OF CELL CYCLE
Hemorrhage appearance in MRI
T1 , T2
Hyperacute : I (iso) Bleed (bright)
Acute: I (iso) Die (dark)
Early sub: Bleed (bright) Die (dark)
Late sub: Bleed (bright) Bleed (bright)
Chronic: Die (dark) Die (dark)
Coils that simultaneously measure the signal from orthogonal views that have 2 separate amplifiers and gain controls
RF QUADRATE COILS
Broadband RF Noise. A narrow band pattern of black and white alternating noise aka “zipper artifact”
Herringbone artifacts
Compensation: Faraday cage
Compensation methods for motion artifacts other than transposing PEG and FEG to relocate motion artifacts out of the region of diagnostic interest.
- Cardiac and respiratory gating
- Respiratory ordering of the phase encoding projections based on loc within respi cycle
- Signal averaging
- Short TE spin echo sequences
- Gradient moment nulling
- Presaturation pulses
- Multiple redundant sampling