Medical Physics | AQA A-Level Physics (7408)
Medical Physics
- 462 questions
- 19 subtopics
- Paper 3 Section B: one option of five
- Paper 3
Medical physics is one of the five optional topics, sat on Paper 3.
It applies optics, sound and radiation physics to the body: how the eye and ear work and how their defects are corrected, then the imaging techniques built on ultrasound, X-rays, magnetic resonance and gamma emission.
Sample questions from Medical Physics
Answer each one closed book first, then open the answer.
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Physics of vision
Which type of photoreceptor is highly sensitive to low light intensities?
Show the answer
Rods are highly sensitive to low light intensities. -
Ear as a sound detection system
Which ossicle connects directly to the oval window, and what is its common name?
Show the answer
The stapes, commonly called the stirrup. -
Defects of hearing
How does age-related hearing loss appear on audiometric tests?
Show the answer
The hearing loss is reflected in altered equal loudness curves, showing reduced sensitivity compared to normal hearing. -
Ultrasound imaging
Define attenuation in the context of ultrasound imaging.
Show the answer
Attenuation is the gradual loss of ultrasound intensity as it travels through tissue, due to absorption and scattering -
Magnetic resonance (MR) scanner
What type of magnet produces the main magnetic field in an MR scanner?
Show the answer
A superconducting magnet. -
Image detection and enhancement
State one advantage of flat panel detectors related to image handling and archiving.
Show the answer
They enable easy storage, transmission and retrieval of images in digital format. -
CT scanner
Why does a monochromatic X-ray beam allow more accurate attenuation measurements in CT?
Show the answer
Because all photons have the same energy, the attenuation coefficient is constant and predictable, enabling accurate calculation of tissue properties. -
Half-life
Why does effective half-life account for two separate processes?
Show the answer
Because both radioactive decay (physical) and biological removal occur simultaneously, each contributing to the reduction in activity.
The 19 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Physics of vision | Refraction at the cornea and lens, accommodation, the retina, and rod and cone vision. | 38 |
| Defects of vision and their correction using lenses | Lens power in dioptres, the lens equation, and correcting myopia and hypermetropia. | 36 |
| Ear as a sound detection system | The outer, middle and inner ear, pressure amplification by the ossicles, and the cochlea. | 28 |
| Sensitivity and frequency response | Sound intensity, the decibel and dBA scales, and equal loudness curves. | 24 |
| Defects of hearing | Noise-induced and age-related hearing loss, and how each appears on an audiogram. | 17 |
| Simple ECG machines and the normal ECG waveform | Detecting and amplifying the heart's electrical signal, and the P, QRS and T features. | 17 |
| Ultrasound imaging | Acoustic impedance, the reflection coefficient, coupling gel, and A-scans and B-scans. | 28 |
| Fibre optics and endoscopy | Total internal reflection, coherent and non-coherent bundles, and the advantages of endoscopy. | 24 |
| Magnetic resonance (MR) scanner | The superconducting magnet, gradient coils, RF excitation of protons, and the relaxation signal. | 12 |
| The physics of diagnostic X-rays | X-ray production, the continuous and characteristic spectra, and controlling intensity and energy. | 36 |
| Image detection and enhancement | Flat panel detectors, image intensifiers, and contrast media such as barium and iodine. | 26 |
| Absorption of X-rays | The exponential attenuation equation, the attenuation coefficients, and half-value thickness. | 21 |
| CT scanner | How a CT image is reconstructed, and the dose and cost weighed against the detail gained. | 19 |
| Imaging techniques | The tracers used in nuclear medicine, what makes a good one, and the technetium generator. | 29 |
| Half-life | Physical, biological and effective half-life, and the formula relating them. | 16 |
| Gamma camera | The collimator, scintillator and photomultiplier, and how an image is built up. | 25 |
| Use of high-energy X-rays | External radiotherapy, why the source is rotated, and why cancer cells are more vulnerable. | 14 |
| Use of radioactive implants | Brachytherapy, why beta emitters are used, and the short range of the radiation. | 9 |
| Imaging comparisons | Weighing X-ray, CT, ultrasound, MRI and PET on resolution, dose, cost and availability. | 43 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
AQA A-Level Physics Active Recall Guide
Every topic, not just this one. 3,682 questions with their answers.