Sample interview questions: Describe the principles behind laser-induced acoustic imaging and its applications in medical imaging.
Sample answer:
Laser-induced acoustic imaging (LAII) is a non-invasive imaging technique that uses short-pulsed lasers to generate ultrasonic waves within biological tissues. These ultrasonic waves are then detected using a transducer, and the resulting signals are processed to create images of the tissue.
Principles of Laser-induced Acoustic Imaging:
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Laser Pulse Generation: A short-pulsed laser is used to generate a high-intensity, ultrashort laser pulse. The pulse duration is typically in the picosecond or nanosecond range.
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Laser-Tissue Interaction: When the laser pulse interacts with the tissue, it is absorbed by the chromophores (light-absorbing molecules) present in the tissue. This absorption results in the rapid heating and expansion of the tissue, generating an acoustic wave.
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Ultrasonic Wave Propagation: The generated acoustic wave propagates through the tissue at a speed determined by the tissue’s mechanical properties. The speed of sound in biological tissues is typically in the range of 1500-2000 m/s.
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Ultrasonic Wave Detection: An ultrasonic transducer is placed on the surface of the tissue to detect the propagating acoustic waves. The transducer converts the acoustic waves into electrical signals, which are then amplified and processed.
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Image Reconstruction: The processed electrical signals are used to reconstruct images of the tissue. The images provide information about the tissue’s structure, density, and other acoustic properties.
Applications of Laser-induced Acoustic Imaging in Medical Imaging:
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Breast Imaging: LAII has been used for breast cancer detection and characterization. It can differentiate between benign and malignant lesions based on their acoustic properties.
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Thyroid Imaging: LAII is used in the evaluation of thyroid nodules. It can help distinguish between benign and malignant nodules, reducin… Read full answer