Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Medical Physics > Key Words > Flashcards

Key Words Flashcards

1
Q

Accommodation

A

The ability of the eye to adjust its focal length.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Acoustic impedance (Z)

A

The product of the density, r, and the speed of sound, c, in that material.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Action potential

A

The change in electrical potential that occurs across a cell membrane during the passage of a nerve impulse.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

A-scan (amplitude scan)

A

A range-measuring system, which records the time taken for an ultrasonic pulse to travel to an interface in the body and be re ected back.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Astigmatism

A

A defect in the eye or in a lens caused by a deviation from spherical curvature, which results in distorted images.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Attenuation

A

The reduction of intensity as a wave travels through a material.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Auditory nerve

A

Carries auditory sensory information from the cochlea of the inner ear directly to the brain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Biological half-life (TB)

A

The time required for the body to eliminate half of an administered dose of any substance by regular physiological processes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Bremsstrahlung (‘braking’ radiation)

A

Electromagnetic radiation produced by the acceleration or especially the deceleration of a charged particle after passing through the electric and magnetic elds of a nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

B-scan (brightness scan)

A

A diagnostic test used in optometry and ophthalmology to produce a two-dimensional, cross-sectional view of the eye and the orbit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Characteristic X-rays

A

Emitted when outer-shell electrons ll

a vacancy in the inner shell of an atom, releasing X-rays in a pattern that is ‘characteristic’ to each element.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Ciliary muscle

A

One of the muscles around the lens of the eye that can change the shape of the lens in order to produce a clear image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cladding

A

The outer covering of an optical fibre, which confines light to the core.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Coherent bundle

A

An ordered collection of optical bres that can carry images.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Cochlea

A

Part of the inner ear where sound vibrations are converted into electrical signals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Computed tomography

CT

A

Radiography in which a three-dimensional image of a

body structure is constructed by computer from a series of plane cross-sectional images made along an axis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

concave lens

A

A lens that spreads a parallel beam into a divergent emergent beam.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

cones

A

Light-sensitive cells in the retina, responsible for colour vision.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Contrast

A

In X-ray image: the variation in brightness of the image due to differential absorption of X-rays in the patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Contrast medium

A

A material of high density and atomic number put into the body to enable soft organs to be visualised on an X-ray image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

convex lens

A

A lens that causes a parallel beam to converge to a point called the focus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

cornea

A

The outer covering of the front of the eye, where most of the refraction of light takes place.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

CT scanner

A

Medical scanner

that uses beams of X-rays to produce high-contrast images of a cross-section through the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

dBA

A

dBA-weighted decibels are
a measurement of the relative loudness of sounds in air as perceived by the human ear. In
the A-weighted system, the decibel values of sounds at low frequencies are weighted in such a way that they are reduced compared with unweighted decibels (dB). This weighting is applied because the human ear is less sensitive at low and high audio frequencies and the A weighting matches more closely the human ears frequency response to sound levels.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
dB scale
The logarithmic scale used to measure intensity of sound.
26
Decibel (dB)
The unit used to measure the intensity of a sound
27
Depolarisation
A sudden change within a cell, during which the cell undergoes a dramatic electrical change.
28
Eardrum
The membrane of the middle ear, which vibrates in response to sound waves.
29
Electrocardiograph (ECG)
An instrument used in the | detection and diagnosis of heart abnormalities that measures the electrical activity of the heart.
30
Endoscope
An instrument that can be introduced into the body to give a view of its internal parts.
31
excited
Being at an energy level higher than the ground state.
32
Far point
the farthest point from the eye at which images are clear
33
Flat-panel (FPD) detectors
A class of solid-state X-ray digital radiography devices similar in principle to the image sensors used in digital photography and video.
34
Focal length (f)
The distance between the principal focus of a lens and its centre.
35
Focus
The point where light rays originating from a point on the object converge.
36
Fovea
A region on the retina with a high concentration of cone cells.
37
Gamma camera
A device used to image gamma radiation emitting radioisotopes.
38
Image intensifier
A device used in the X-ray technique uoroscopy to produce a visible image using a lower dose of X-rays.
39
Incoherent bundle
A bundle of laments of optical glass or other transparent materials that transmit only light, not optical images.
40
Intensifying screen
Absorbs the energy in the X-ray beam that has penetrated the patient and converts this energy into a light pattern.
41
Intensity
The power of a wave transmitted through unit area perpendicular to the direction of travel of the wave; unit: watts per square metre, Wm-1
42
Intensity attenuation coef cient (μ)
The fraction of a beam of X-rays or gamma rays that is absorbed or scattered per unit thickness of the absorbing material.
43
Intensity level
The relative sound intensity at any point in a sound eld as compared with a speci ed standard intensity.
44
Iris
A thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina
45
Lens
A transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina.
46
Linear attenuation coefficient | μ
A measure of a material’s ability to attenuate X-rays
47
Magnetic resonance (MR)
The excitation of particles (as atomic nuclei or electrons) in a magnetic field by exposure to electromagnetic radiation of a specific frequency.
48
Mass attenuation coefficient (μm)
a measure of a material’s ability to attenuate X-rays that is independent of the material’s density; equal to the linear attenuation coef cient divided by the density
49
Myopia
Short-sightedness: the inability to focus on objects at large distances from the eye.
50
Near point
The closest distance from the eye at which an object can be brought into focus.
51
Nuclear magnetic resonance (NMR)
The absorption of electromagnetic radiation at a precise frequency by a nucleus in an external magnetic eld.
52
Optic nerve
A paired nerve that transmits visual information from the retina to the brain
53
Optical fibres
Thin transparent fibres of glass or plastic that transmit light throughout their length by internal reflections; used in medical instruments to view otherwise inaccessible parts of the body.
54
Ossicles
Three bones in the middle ear, malleus, incus and stapes, that are among the smallest bones in the human body.
55
Photocathode
A negatively charged electrode in a light-detection device such as a photomultiplier or phototube that is coated with a photosensitive compound.
56
Photodetector
A device that detects or responds to incident light by using the electrical effect of individual photons.
57
Photodiode
A semiconductor diode that, when exposed to light, generates a potential difference or changes its electrical resistance
58
Photomultiplier
An instrument containing a photoelectric cell and a series of electrodes, used to detect and amplify the light from very faint sources.
59
Piezoelectric effect
The ability of certain materials to generate an electric charge in response to applied mechanical stress.
60
Piezoelectric transducer
A device that generates a potential difference when it is compressed or expanded; used to generate and detect ultrasound.
61
Polarised
A transverse wave is polarised when the vibration of the wave is con ned to one direction.
62
Power
The rate at which energy is transferred or at which work is done, measured in joules per second, or watts, W.
63
Principal axis
An imaginary line drawn at right angles to a lens passing through the optical centre, used in constructing ray diagrams
64
Principal focus
A particular point on the optical axis of a lens where light is focused.
65
Pulse rate
The number of times your heart beats per minute.
66
pupil
The aperture of the eye.
67
Radioactive tracer
A radioactive isotope used for medical imaging and which is tracked and detected by an external radiation detector.
68
real image
An image formed by the convergence of rays of light; it can be formed on a screen
69
Repolarised
Describes the change in the cell membrane potential that returns it to a negative value just after the depolarisation phase of an action potential has changed the membrane potential to a positive value.
70
Resonance
Occurs when a system accepts energy from a driving source at its natural frequency – the amplitude increases greatly.
71
Retina
A tissue of light-sensitive cells lining the back of the eye.
72
Rhodopsin
A photopigment present in rod cells, which disassociates when it absorbs a photon of light
73
Rods
Light-sensitive cells in the retina, which respond well in low light conditions
74
Scintillator
A material that uoresces when struck by a charged particle or high-energy photon
75
Source focal spot
The small area of the target of an X-ray tube on which the electron beam is focused; it is an important factor in the ability of an X-ray machine to produce a sharp image.
76
Thermionic emission
The process by which electrons are released from the surface of a heated metal
77
Threshold of hearing (I0)
The lowest sound intensity that can be detected by a healthy human ear, de ned as 1×10-12 W m-2.
78
Ultrasound
Sound waves with a frequency above 20 kHz.
79
Virtual image
An image caused by rays that do not converge; the image can be seen by the eye but not formed on a screen.

Medical Physics (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions