physics quiz for tommorow

X-ray photon

A particle of electromagnetic radiation that can penetrate body tissues to form an image.

Differential Absorption

The varying degrees to which different anatomic parts absorb the primary x-ray beam, creating a structurally representative image.

Attenuation

A reduction in the energy or number of photons in the primary x-ray beam due to absorption and scattering.

Photoelectric Effect

An interaction in which an incoming photon has enough energy to eject an inner-shell electron, leading to absorption.

Compton Effect

An effect where an incoming photon loses energy when it ejects an outer-shell electron and changes direction.

Transmission

The passage of x-ray photons through the body without any interaction with atomic structures.

Scattering

The deflection of photons from their original path due to interactions with tissue, which affects image quality.

Factors Affecting Beam Attenuation

Elements including tissue thickness, type of tissue, tissue density, and x-ray beam quality that influence how much x-ray photons are absorbed or scattered.

Image Receptor

A device that captures the radiation after it has passed through the body, forming the radiographic image.

Higher-penetrating x-rays

X-rays with shorter wavelengths and higher frequencies, which are more likely to transmit through tissues without interacting.

Lower-penetrating x-rays

X-rays with longer wavelengths and lower frequencies, which are more likely to interact with atomic structures and be absorbed.

Brightness

The amount of luminance (light emission) of a display monitor.

Exposure Indicator

A numeric value indicating the level of radiation exposure to the digital image receptor.

Digital Image Processing

Technique that compensates for exposure errors and maintains brightness in images.

Quantum Noise

Increased noise in images caused by underexposure due to insufficient radiation.

Saturation

Result of extreme overexposure in imaging, leading to loss of detail.

Window Level

The midpoint setting of the range of densities visible in an image that can affect overall brightness.

Contrast

Differences in brightness levels needed to differentiate among anatomic tissues.

Radiographic Contrast

Contrast that affects the visibility of structural lines that make up the recorded image.

Subject Contrast

Refers to the absorption characteristics of anatomic tissue and the quality of the x-ray beam.

Contrast Resolution

The ability of the system to distinguish between small objects that attenuate the x-ray beam similarly.

Beam Attenuation

The reduction of the intensity of the X-ray beam as it passes through matter.

Factors Affecting Beam Attenuation

Tissue thickness, atomic number, density, and beam quality.

Tissue Thickness

Increased thickness decreases transmission of the X-ray beam.

Tissue Atomic Number

Higher atomic number increases beam attenuation.

Tissue Density

Greater tissue density results in increased beam attenuation.

X-ray Beam Quality

Higher quality beams penetrate tissues better than lower quality beams.

Scattered Radiation

Radiation that is deflected from its original path and contributes to image fog.

Primary Radiation

The initial radiation emitted from the X-ray tube before it interacts with the patient.

Exit Radiation

The radiation that emerges from the patient, including both transmitted and scattered radiation.

Fog

Unwanted exposure on an image caused by scattered radiation.

Latent Image

The invisible image that exists on the exposed film before processing.

Manifest Image

The visible image on the exposed film after it has been processed.

Digital Imaging

The most common method in radiography to create radiographic images.

Matrix

A grid of rows and columns in a digital image composed of numeric data.

Pixel

The smallest unit of a digital image, represented by a numeric value.

Bit Depth

The number of bits used to represent the brightness of a pixel in a digital image.

Quality Radiographic Image

An image that accurately represents the anatomic area of interest for diagnosis.

Contrast

The difference in brightness between different parts of an image.

Spatial Resolution

The ability of an imaging system to resolve detail in the image.

Sharpness

The clarity of the edges in the radiographic image.

Contrast

The difference in brightness between the lightest and darkest areas of an image.

Window Width

The range of pixel values that affect the contrast of an image.

Spatial Resolution

The smallest object that can be detected in an image, determined by pixel size and spacing.

Field of View (FOV)

The dimensions of an anatomic area as represented in an image.

Modulation Transfer Function (MTF)

A measure of an imaging system's ability to display contrast across varying sizes of anatomic objects.

Detective Quantum Efficiency (DQE)

A measurement of the efficiency of an image receptor in converting x-ray exposure into a quality radiographic image.

Distortion

The misrepresentation of an object's size or shape in an image.

Size Distortion

An increase in the image size compared with the actual size of the object.

Shape Distortion

A change in the shape of an object in an image, which can appear as elongation or foreshortening.

Scatter

Unwanted radiation that decreases contrast by fogging images and masking brightness levels.

Image Artifact

Any unwanted image on a radiograph that can obscure anatomical information.

Quantum Noise

Image noise that contributes no useful diagnostic information and detracts from image quality.

Signal-to-Noise Ratio (SNR)

A method describing the strength of radiation exposure compared to the noise in the digital image; a higher SNR improves image quality.

Contrast-to-Noise Ratio (CNR)

A method that describes contrast resolution relative to the noise in a digital image; increasing CNR enhances visibility of anatomical details.

Anatomic Visibility

The clarity of anatomical details in an image; affected by the presence of artifacts and noise.