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An ultrasound A-scan is used to find the length / l of an eye as shown in Figure 6 - AQA - A-Level Physics - Question 4 - 2019 - Paper 5
Question 4
An ultrasound A-scan is used to find the length / l of an eye as shown in Figure 6. Figure 7 shows the simplified A-scan for the eye. A short pulse of ultrasound is ... show full transcript
Worked Solution & Example Answer:An ultrasound A-scan is used to find the length / l of an eye as shown in Figure 6 - AQA - A-Level Physics - Question 4 - 2019 - Paper 5
Step 1
Discuss whether an A-scan or a B-scan should be used for amniocentesis.
Answer
Differences between A-scan and B-scan
A-scan
- Provides a one-dimensional view, resulting in a simple graph of amplitude versus time.
- Primarily useful for measuring distances, like lengths of organs.
B-scan
- Provides a two-dimensional cross-sectional image, giving more information about the structure.
- Useful for visualizing the position of organs, making it suitable for complex procedures.
Advantages and Disadvantages
A-scan
Advantages:
- Simple and requires less time to perform.
- Easier to interpret for specific measurement tasks.
Disadvantages:
- Limited information as it does not provide detailed visualization of surrounding structures.
B-scan
Advantages:
- Offers detailed images of the anatomy, allowing for better positioning information.
- More useful for procedures like amniocentesis which require an accurate location of the fetus and placenta.
Disadvantages:
- More complicated interpretation, requiring trained personnel and more time.
Recommendation
For amniocentesis, a B-scan should be preferred due to its ability to provide a detailed image of the fetus and surrounding structures, which is crucial for safely guiding the procedure.