24 Questions
Which of the following is a fundamental learning outcome of the Basic Radiological Imaging for Musculoskeletal Medicine class?
Discuss the fundamentals of medical imaging
What is the main difference between ionizing and non-ionizing radiation in medical imaging?
Ionizing radiation has sufficient energy to remove tightly bound electrons from atoms, creating ions, while non-ionizing radiation does not have this capability
Which imaging modality is NOT mentioned as a part of the musculoskeletal imaging modalities?
PET scan
How are digital images stored in a computer's memory?
As a series of pixels, where each pixel is represented by a square box with intensity corresponding to the brightness of the object at a specific location
What principle does ultrasound technology work on?
Reflection and intensity of sound waves
What is the frequency range for ultrasound in tissue?
20 kHz – 20 MHz
What causes the 'spin' of the protons to flip in MRI?
Absorption of RF pulse by the molecules
What allows distinguishing between different tissue types in MRI?
Measurement of recovery times (T1 and T2)
What is the speed of sound in water?
1500 m/s
What does the intensity of the reflected ultrasound wave tell us?
About the density of the reflecting medium
What is the frequency range for sound in air?
20 – 20,000 Hz
What is the frequency range for sound in water?
20 – 20,000 Hz
Which type of radiation can break bonds and cause electrons to be freed from an atom?
Ultraviolet radiation
What is the scanning technique used to determine bone density and diagnose osteoporosis?
Dual Energy X-ray Absorptiometry (DEXA)
What does BMD stand for in the context of bone density measurement?
Bone Mineral Density
How is the fracture risk related to the T-score in bone density measurement?
Fracture risk doubles with every Standard Deviation (SD) below normal
What is the primary function of the linear attenuation coefficient (lac) in Computerized Tomography (CT)?
To calculate absorption as a function of position within the subject
What does a modern CT machine use to obtain detailed information on thousands of tiny volumes within a subject?
Multiple x-ray projections
What does the World Health Organization use to define bone density levels?
T-score
What is the primary purpose of a circular 'gantry' in modern CT machines?
To house the x-ray sources and detectors
What is the color scheme in a CT scan based on?
Absorption values
What is the primary purpose of Dual Energy X-ray Absorptiometry (DEXA) in bone density measurement?
To determine bone density and diagnose osteoporosis
What is the main characteristic of heavy elements like calcium in absorbing x-rays?
They are good absorbers of x-rays
What is the primary function of non-visual, computerized medical imaging systems?
To identify the object to be imaged, apply appropriate technology, and measure the received signal as a function of location
Study Notes
Medical Imaging Technologies and Their Applications
- Array elements have color and brightness values assigned based on measured parameters like absorption and emission of radiation
- Non-visual, computerized medical imaging systems follow a simple procedure: identify the object to be imaged, apply appropriate technology, and measure the received signal as a function of location
- Each matrix element corresponds to a physical position within the region of study, with its numerical value representing the strength of the received signal
- Ionizing radiation with a frequency > ~1 x 10^15 Hz can break bonds and cause electrons to be freed from an atom
- X-rays are absorbed differently by materials, with heavy elements like calcium being good absorbers, and soft tissues having similar absorption characteristics, making them difficult to distinguish in standard x-ray pictures
- Dual Energy X-ray Absorptiometry (DEXA) is a scanning technique used to determine bone density and diagnose osteoporosis, with bone mineral density (BMD) measured using two low-dose X-rays absorbed differently by bones and soft tissues
- BMD is compared to norms, and a T-score is given as the number of Standard Deviations (SD) between the BMD and the mean BMD of a sample group
- World Health Organization defines bone density levels as normal, low bone mass, osteoporosis, and severe osteoporosis, with fracture risk doubling with every SD below normal
- Computerized Tomography (CT) involves passing thin x-ray beams through the body and using the linear attenuation coefficient (lac) to calculate absorption as a function of position within the subject
- Modern CT machines use multiple x-ray projections to obtain detailed information on thousands of tiny volumes within a subject
- CT scans create a 3-d array with each element corresponding to a specific location within the patient, and a color scheme is developed based on absorption values
- In modern CT machines, the patient slides through a circular 'gantry' containing x-ray sources and detectors, creating a spiral motion and generating many x-ray projections
Test your knowledge of medical imaging technologies and their applications with this quiz. Explore topics such as X-rays, dual energy X-ray absorptiometry (DEXA), bone density measurement, and computerized tomography (CT).
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