Medical Design Briefs - October 2024 - 15

Advanced medical imaging. (Credit: Stock Spectrum/AdobeStock)
T
he integration of advanced technologies is driving
significant improvements in medical imaging and diagnostic
capabilities. This article explores key modalities
like ultrasound, MRI, OCT, x-ray, CT, and PET,
as well as several emerging trends that are driving
performance improvements (see Table 1).
Ultrasound
Noninvasive diagnostic ultrasound is used to imagine tissues
inside the body. Ultrasound probes (i.e., transducers) produce
sound waves, and when placed on the skin or inside the body,
they transmit those waves into the body and detect returning
echoes (see Figure 1). Based on the speed of sound and the timing
of echo returns, the system calculates the distance between
the transducer and the tissue. These distances are used to create
two-dimensional images of the tissues of interest. Diagnostic ultrasound
includes images of internal organs and functional
maps to visualize changes happening inside the body.
Ultrasound systems include three main components: a
transmitter, a transducer, and a receiver. The transmitter and
receiver are electronic components while the transducer is
mechanical. The transducer is responsible for generating and
receiving ultrasound waves. With the help of piezoelectric
quartz, like PZT and ceramics, transducers convert electrical
energy into mechanical (i.e., sound) energy. Capacitive micromachined
transducers (cMUTs) and piezoelectric micromachined
transducers (pMUT) are growing in popularity as a
cost-effective alternative.
The transmitter is responsible for amplifying signals from the
transducer; inside the transmitter, power amplifier design plays a
significant role in overall performance. Receivers amplify weak
signals from the transducer for the sake of transmission. Inside
the receiver, the low-noise amplifier (LNA) determines the
signal- to-noise ratio (SNR), and by extension, performance.
Magnetic Resonance Imaging (MRI)
Magnetic resonance imaging (MRI) leverages a magnetic field
and computer-generated radio-frequency pulses to generate detailed
2D or 3D images of organs and tissues inside the body.
Technology Signal*
Ultrasound
Sound
MRI
Endoscopy
OCT
X-Ray
CT-Scan
PET
SPEC
Gamma Radiation 10s of EHz+
X-Ray Radiation 10s of PHz+
RF Signals
Visible and IR
Frequency
10s of KHz+
10s of MHz+
Applications
Blood vessels, muscles, tendons,
and blood flow
Soft tissue
100s of GHz+ Gastroscopy, brochoscopy,
uretroscopy, neuroscopy
Opthalmology, dermatology,
cardiology, oncology
Bones, soft tissue
Head, neck, lungs, cardiac,
abdominal, bones, ligaments
Oncology
Oncology
Medical Design Briefs, October 2024
* Signals range from sound waves at 20 kHz to gamma radiation at exa-hertz .
Table 1. Popular imaging modalities and their relevant clinical applications.
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Medical Design Briefs - October 2024

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