BRAINCAKEThe Piezoelectric Effect
Ultrasound for medical imaging is produced and detected using the piezoelectric effect.
Some crystals, such as natural quartz and the ceramic lead zirconate titanate (PZT), are made of ions arranged so that squeezing the crystal shifts the positive and negative charges slightly relative to each other. The piezoelectric effect is the production of a potential difference across a crystal when it is compressed or stretched. Compressing it gives a p.d. one way; stretching it gives a p.d. the opposite way.
The effect also works in reverse. Applying a p.d. across the crystal makes it change shape: one polarity makes it expand, and reversing the p.d. makes it contract.
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More in Medical Imaging
- The Gamma Camera
- Diagnosis with a Gamma Camera
- PET Scanning
- Ultrasound
- Ultrasound Transducers
- A-scans and B-scans
- Acoustic Impedance
- Reflection at Boundaries
All 20 lessons in Medical Imaging · All OCR A-level Physics topics