Diagnostic Imaging Modalities Flashcards
What organization is the regulator of all imaging modalities in Ontario?
CMRITO
college of medical radiation and imaging technologists of ontario
What modalities does the CMRITO regulate?
-radiography
-nuclear medicine
-radiation therapy
-MRI
-diagnostic medical sonography
-national voice for MRT professionals
-works with provincial organization to represent and protect the MRT
(OAMRS, PLI, continuing education)
CAMRT
Canadian association of medical radiation technologists
-national voice for DMS in Canada
(PLI, continuing education)
Sonography Canada
T/F
Radiation therapy is considered a treatment modality and not imaging modality
True
Treatment modality that employs ionizing radiation to treat cancers and various diseases
Radiation therapy
-based on the acoustic properties of the tissue it is passing through
-sound waves are produced by electrical stimulation of a specialized crystal in the transducer
-sound waves are reflected at differing tissue interfaces
*the greater the difference, the greater the echo
Ultrasound
What is the average cost of an ultrasound machine?
$50,000
What is the average exam time of an ultrasound?
30 minutes
T/F
Ultrasound machines are very common, found everywhere
True
What are the 2 contributors to image creation in ultrasound?
-transducer
-image receptor
Production of multi frequency sound waves
US
Transducer
Transducer receiving echoed signal
US
Image receptor
What are the 4 imaging descriptors in ultrasound?
-anechoic
-hyperechoic
-hypoechoic
-isoechoic
US
a structure/region that does not produce any echos (black)
Anechoic
US
highly reflective (echogenic) structures as compared with surrounding structures (white)
Hyperechoic
US
a structure/region that produces fewer echos than normal (dark)
Hypoechoic
US
a structure/region that produces a similar number of echoes as are produced by surrounding tissue
Isoechoic
What are some advantages to ultrasound?
-non ionizing
-relatively fast, inexpensive and available
-ability to differentiate between cystic, solid and complex
-may be used for image guidance of biopsies
-excellent for dynamic evaluations of joints
What modality is the gold standard for pancreas, liver, gallbladder, and uterus?
Ultrasound
What are some disadvantages of ultrasound?
-Limited resolution and demonstration of structures
-operator dependent
-presence of acoustic barriers (air, bone)
T/F
Acoustic barriers will reflect all of the sound back to the transducer and nothing beyond them will be imaged
True
-little or no difference in tissue density
-little or no difference in contrast on the image
-can be transmitted, scattered or absorbed
-interaction between energy and matter is of concern
Xray
What is the average cost of an xray machine?
$500,000
What is the average exam time of X-rays
5 minutes
Considered the workhorse of medical imaging
Xray
What are some advantages of xray?
-relatively inexpensive
-very fast
-workhorse of MI
-numerous trained staff
-usually non invasive
What are some disadvantages of xray?
-ionizing radiation
-limited soft tissue differentiation
-oral contrast needed to demonstrate GI system
-can be invasive with IV contrast
What is the gold standard in early detection of breast cancer?
Mammography screening
What 2 images are tone for mammo screening?
2 of each breast
Cc- cranial caudal
MLO- media lateral oblique
What is done if suspicious areas are identified on a screening mammogram?
Additional images ( coned down or mag. Projections)
When is a diagnostic mammogram done?
When palpable nodule is present
What is the average cost of a mammography machine?
$500,000
What is the average time of a mammo exam?
10 minutes
-produces cross sectional image by scanning a slice of tissue from multiple angles as it goes around in an arc with a narrow xray beam
-calculated the linear coefficient
-allows for image manipulation with windowing/leveling and image reconstruction into Sagittal, coronal or 3D images
CT
What is the average cost of a CT scanner?
1 million
What is the average exam time for CT?
15 minutes
Gold standard for trauma
CT
Air -1000
Water 0
Bone 1000
Hounsfield units for CT
What factors contribute to image creation in CT?
-collimated xray beam attenuation detection
-detectors receive the attenuated signal
What are the image descriptors of CT?
-CT number (HU) reflects the attenuation of a tissue to water
-window width - greyscale, contrast scale
-window level - midpoint of densities, brightness
-provides imaging based on structural/anatomical properties and functional/physiological properties
-uses magnetic fields and radio waves to produce an image
-the rate at which the nuclei recover produces the image
-uses large magnetic, radio transmitter, powerful computer to produce images
MRI
T/F
MRI uses non-ionizing, which is good. But could potentially be harmful due to magnets
True
How are MRI images produced?
-magnet is turned on and causes the proton in the hydrogen nucleus to spin (precession)
-radio waves are sent in pulses (resonance) with magnet
-radio frequency pulses are off the nuclei begin to slow down spinning, this is the rate of relaxation (T1 and T2)
-this gives info on normal tissue or pathological tissue
What is the average cost of an MRI machine?
2.5 million
What is the average exam time for MRI?
30-45 minutes
What are the advantages of MRI?
-structural and functional capabilities
-soft tissue differentiation
-complimentary to other modalities
-does not use ionizing radiatoon
What is the modality of choice for imaging CNS and spine
MRI
What are the disadvantages of MRI?
-expensive
-complex to operate/interpret
-long scan times
-claustrophobia
-metal in body
-MRI compatible equipment in rooms increase cost
-patient ingests or receives (IV) radio pharmaceuticals that emit radiation from the patient to create an image
-a gamma camera detects that radiation emitted from the patient
-creates a scintigraphic image
Nuclear medicine
-provides physiological information (functional maps) based on metabolic uptake of radionuclides in tissues and organs
-very poor resolution
-critical contribution to assessing spread of disease
Nuclear medicine
What is the most common used include in nuclear medicine?
Technetium 99m
T/F
Nuclear medicine emits 140kev gamma radiation (gamma camera)
True
What is a gamma camera used for?
Fractures, infections, tumors, Mets
Cost = $500,000
Time = 45 minutes exams
What is the PET/MRI hybrid used for?
Revolution in oncology, surgical planning, radiation therapy
Cost = $2 million
-same as radiopharmaceuticals as conventional NM
-gamma camera with ability to rotate around patient (like CT)
-poor resolution and sensitivity
SPECT
-uses different radiopharmaceuticals that decay by positron emission
-produces a metabolic image
-uses multiple gamma detectors, can reformat into 3D images
-higher quality images than SPECT
-especially useful in oncology
-technologist receives larger doses
PET
Gamma camera that detects gamma radiation emitted from patient
Image creation of NM
Rotating gamma camera for multiplanar gamma radiation collection
SPECT image creation
Increased uptake directly proportional to the emission of gamma radiation
Hot spot
Reflection of decreased uptake directly proportional to the emission of gamma radiation
Cold spot
-radiopharmaceuticals that emits a positron - through the collection following annihilation, two gamma rays are created
-two opposite gamma cameras detect gamma radiation simultaneously emitted from patient
PET image creation
What are the advantages of NM?
-images physiological/metabolic function of tissue
-safer for patients with iodine allergies
-earlier diagnosis and better prognosis (very sensitive)
What are the disadvantages of NM?
-uses ionizing radiation
-not cheap, funding model complex
-radioactive nuclide supply issues
-lacks anatomical information
