Key term
AQA A-Level Physics 7408
Measurements and Their Errors
Particles and Radiation
Topic overviewConstituents of the atomStable and unstable nucleiParticles, antiparticles and photonsParticle interactionsClassification of particlesQuarks and antiquarksApplications of conservation lawsThe photoelectric effectCollisions of electrons with atomsEnergy levels and photon emissionWave-particle duality
Waves
Mechanics and Materials
Electricity
Further Mechanics and Thermal Physics
Fields and Their Consequences
Topic overviewFieldsNewton's lawGravitational field strengthGravitational potentialOrbits of planets and satellitesCoulomb's lawElectric field strengthElectric potentialCapacitanceParallel plate capacitorEnergy stored by a capacitorCapacitor charge and dischargeMagnetic flux densityMoving charges in a magnetic fieldMagnetic flux and flux linkageElectromagnetic inductionAlternating currentsTransformers
Nuclear Physics
AstrophysicsOptional topic
Topic overviewAstronomical telescope consisting of two converging lensesReflecting telescopesSingle dish radio telescopes, I-R, U-V and X-ray telescopesAdvantages of large diameter telescopesClassification by luminosityAbsolute magnitude, MClassification by temperature, black-body radiationPrinciples of the use of stellar spectral classesThe Hertzsprung-Russell (HR) diagramSupernovae, neutron stars and black holesDoppler effectHubble's lawQuasarsDetection of exoplanets
Medical PhysicsOptional topic
Topic overviewPhysics of visionDefects of vision and their correction using lensesEar as a sound detection systemSensitivity and frequency responseDefects of hearingSimple ECG machines and the normal ECG waveformUltrasound imagingFibre optics and endoscopyMagnetic resonance (MR) scannerThe physics of diagnostic X-raysImage detection and enhancementAbsorption of X-raysCT scannerImaging techniquesHalf-lifeGamma cameraUse of high-energy X-raysUse of radioactive implantsImaging comparisons
Engineering PhysicsOptional topic
Turning Points in PhysicsOptional topic
Topic overviewCathode raysThermionic emission of electronsSpecific charge of the electronPrinciple of Millikan's determination of the electronic charge, eNewton's corpuscular theory of lightSignificance of Young's double slits experimentElectromagnetic wavesThe discovery of photoelectricityWave–particle dualityElectron microscopesThe Michelson-Morley experimentEinstein's theory of special relativityTime dilationLength contractionRelativistic mass and energy
ElectronicsOptional topic
Topic overviewMOSFET (metal-oxide semiconducting field-effect transistor)Zener diodePhotodiodeHall effect sensorDifference between analogue and digital signalsLC resonance filtersThe ideal operational amplifierInverting amplifier configurationNon-inverting amplifier configurationSumming amplifier configurationReal operational amplifiersCombinational logicSequential logicAstablesPrinciples of communication systemsTransmission mediaTime-division multiplexingAmplitude (AM) and frequency modulation (FM) techniques
Medical Physics
Image detection and enhancement
- 5 things to know
- Paper 3, section B
Overview
Flat panel detectors, intensifying screens and image intensifiers for X-ray imaging, and how a barium meal uses an X-ray opaque material to enhance contrast in images of the gut.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
How does a flat panel detector improve on photographic film?
Key term
What is contrast enhancement, and why does barium sulfate work as a contrast agent?
Key term
What is the role of the input phosphor screen in an image intensifier?
Key term
What do the electron focusing electrodes do in an image intensifier?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Name the three main components of a flat panel detector (FPD).
Model answer
An X-ray scintillator layer, an array of photodiode pixels, and electronic scanning circuitry.
- 2
What is the function of the X-ray scintillator layer in a flat panel detector?
Model answer
It converts incident X-rays into visible light photons.
- 3
What role does the photodiode pixel array play in a flat panel detector?
Model answer
It detects the visible light produced by the scintillator and converts it into electrical signals.
- 4
What is the purpose of the electronic scanning circuitry in a flat panel detector?
Model answer
It reads out the electrical signals from each photodiode pixel to construct a digital image.
- 5
How does a flat panel detector differ from photographic film regarding image availability?
Model answer
Flat panel detectors provide immediate image availability without requiring chemical processing, unlike photographic film.
- 6
Why can a flat panel detector visualise tissues of different densities better than photographic film in a single exposure?
Model answer
Flat panel detectors have a wider dynamic range than photographic film.
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