Introduction to SI Units and Atomic Structure
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Questions and Answers

What is the standard unit of mass in the International System of Units (SI)?

  • Pounds
  • Grams
  • Ounces
  • Kilograms (correct)

Which of the following defines the distance light travels in a vacuum in 1/299792485 second?

  • Length (correct)
  • Frequency
  • Velocity
  • Mass

What is the term for the smallest particle of a compound?

  • Ion
  • Element
  • Molecule (correct)
  • Atom

How many base SI units are there?

<p>7 (C)</p> Signup and view all the answers

What term describes the combining ability of an element?

<p>Valence (D)</p> Signup and view all the answers

What does the ‘E’ represent in the equation E=mc^2?

<p>Energy (B)</p> Signup and view all the answers

Which of the following measures the number of waves that pass a given point in a specified time frame?

<p>Frequency (D)</p> Signup and view all the answers

What happens to an element if the Z number of an atom is changed?

<p>The element changes. (C)</p> Signup and view all the answers

What are high frequency x-rays that interact with matter and behave like particles rather than waves?

<p>Photons (A)</p> Signup and view all the answers

How many properties of x-rays did Roentgen identify?

<p>12 (A)</p> Signup and view all the answers

Which type of radiographic equipment typically produces higher amounts of radiation?

<p>Fixed equipment (A)</p> Signup and view all the answers

What is the most common type of tube support used in radiographic setups?

<p>Overhead 3D tubercrane suspension (C)</p> Signup and view all the answers

What type of x-ray tube support allows for both longitudinal and transverse movement?

<p>Overhead 3D tubercrane suspension (D)</p> Signup and view all the answers

What is thermionic emission?

<p>The release of electrons when the filament is heated (A)</p> Signup and view all the answers

What is the charge of the focusing cup in an x-ray tube?

<p>Negative (C)</p> Signup and view all the answers

Which filament in a dual focus arrangement permits better resolution?

<p>Small filament (D)</p> Signup and view all the answers

What does off-focus radiation contribute to the total primary beam?

<p>Up to 25% (C)</p> Signup and view all the answers

What does the anode primacy serve as?

<p>Thermal conductor (A)</p> Signup and view all the answers

What is the relationship between target angle and focal spot size?

<p>Inverse relationship (D)</p> Signup and view all the answers

What type of interaction occurs when an incident electron interacts with the electrostatic field of a nucleus?

<p>Bremsstrahlung interactions (B)</p> Signup and view all the answers

What material is the rotor inside the x-ray tube mainly composed of?

<p>Copper (C)</p> Signup and view all the answers

What is the purpose of a radiographic rating chart?

<p>To identify safe technical factors for x-ray tube operation (D)</p> Signup and view all the answers

What type of photon is produced in coherent scattering that maintains the same energy, frequency, and wavelength as the initial photon?

<p>Secondary photon (C)</p> Signup and view all the answers

What is the term for the series of jumps that electrons undergo between shells during photoelectric absorption?

<p>Characteristic cascade (B)</p> Signup and view all the answers

What is the primary source of scatter in radiographic imaging?

<p>The patient (C)</p> Signup and view all the answers

Which type of grid error occurs when the x-ray tube or grid is improperly positioned?

<p>Off level (B)</p> Signup and view all the answers

Which beam restricting device is the most commonly used in radiography?

<p>Collimator (B)</p> Signup and view all the answers

What defines the number of grid lines per inch or centimeter in radiography?

<p>Grid frequency (A)</p> Signup and view all the answers

What is the relationship between beam restriction and image receptor (IR) exposure?

<p>Inverse relationship (B)</p> Signup and view all the answers

What type of distortion is associated with changes in source-to-image distance (SID) and object-to-image distance (OID)?

<p>Magnification (B)</p> Signup and view all the answers

In digital imaging systems, what is spatial frequency commonly referred to as?

<p>Spatial resolution (B)</p> Signup and view all the answers

What does pixel pitch measure in a digital image?

<p>Distance from the midpoint of one pixel to the midpoint of another (A)</p> Signup and view all the answers

What is the term for an 8-bit word in digital imaging?

<p>Byte (B)</p> Signup and view all the answers

What is the primary function of an ancillary device in radiography?

<p>To meet special patient needs (A)</p> Signup and view all the answers

What is characterized by many shades of grey in a radiographic image?

<p>Low contrast (B)</p> Signup and view all the answers

What is defined as the flat sheet of metal with a central cut opening attached to the x-ray tube port?

<p>Aperture diaphragm (B)</p> Signup and view all the answers

What determines the range of signal in regions of interest?

<p>Histogram (A)</p> Signup and view all the answers

What is the process of correcting the scale of grey in an image that is either underexposed or overexposed?

<p>Rescaling (A)</p> Signup and view all the answers

What term describes the filtering process applied to enhance edges in an image?

<p>High pass filtering (D)</p> Signup and view all the answers

What type of image processing involves calculations applied to small groups of pixels?

<p>Local processing (B)</p> Signup and view all the answers

What is the term used for the ability to effectively represent small energy values in a dataset?

<p>Low contrast resolution (C)</p> Signup and view all the answers

What is the effectiveness of converting data from the IR to the monitor referred to as?

<p>Detective quantum efficiency (B)</p> Signup and view all the answers

What term is used for the process of shifting the focal point away from the anode in an intensification tube?

<p>Magnification tubes (C)</p> Signup and view all the answers

What type of filtering is often used to reduce high frequency noise in imaging?

<p>Low pass filtering (D)</p> Signup and view all the answers

What part of the intensification tube is positively charged and allows electrons to pass through?

<p>Anode (C)</p> Signup and view all the answers

What aspect of tomography determines the thickness of the section being imaged?

<p>Exposure angle (A)</p> Signup and view all the answers

What is commonly used to lower noise during fluoroscopy procedures?

<p>Pixel binning (B)</p> Signup and view all the answers

What is the term for images in tomography that do not correspond with existing anatomical structures?

<p>Phantoms (C)</p> Signup and view all the answers

In fluoroscopy, what is the maximum exposure rate permitted?

<p>10 R/min (A)</p> Signup and view all the answers

What type of interaction leaves a hole in the inner shell due to an incident electron's interaction with an inner shell electron?

<p>Characteristic interactions (C)</p> Signup and view all the answers

At what kilovolt peak (kVp) value can characteristic interactions occur?

<p>70 kVp or higher (A)</p> Signup and view all the answers

What is the process called by which high-energy particles produce ionization through direct atomic collisions?

<p>Particulate interaction (B)</p> Signup and view all the answers

What type of particulate particle can travel a maximum distance of 5 cm?

<p>Alpha particles (C)</p> Signup and view all the answers

Which biological effect has no threshold and occurs randomly?

<p>Stochastic effects (B)</p> Signup and view all the answers

What is the basic principle of radiation protection?

<p>ALARA (B)</p> Signup and view all the answers

What term describes the quantity of radiation received by a patient?

<p>Absorbed dose (B)</p> Signup and view all the answers

Which group of radiation includes high-energy particles?

<p>Ionizing (D)</p> Signup and view all the answers

Which federal agency regulates radiopharmaceuticals and radiation safety requirements for x-ray equipment?

<p>FDA (B)</p> Signup and view all the answers

What is the amount of filtration material that reduces the intensity of a beam to half its original value called?

<p>Half value layer (A)</p> Signup and view all the answers

What happens to beam intensity if the distance is doubled?

<p>4 times less (A)</p> Signup and view all the answers

What is the interaction between very low energy x-ray photons and matter called?

<p>Coherent scattering (D)</p> Signup and view all the answers

In photon interactions, high energy photons primarily interact with which component of the atom?

<p>The nucleus (C)</p> Signup and view all the answers

Flashcards

Mass

The amount of matter in an object.

Length

The distance light travels in a vacuum in 1/299792485 second.

Atomic Mass Number

The total mass of protons and neutrons in an atom.

SI Units

The standard system of measurement using length, mass, time.

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Element

A substance that cannot be broken down into simpler substances.

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Compound

A substance formed by the chemical combination of two or more elements.

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Z number

The number of protons in an atom.

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Matter

Anything that has mass and takes up space.

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X-ray photons

High-energy electromagnetic radiation that behaves like particles.

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Crookes tube

Early x-ray tube, similar to fluorescent lights, with controlled gas inside.

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Coolidge tube

Modern x-ray tube, using a heated filament to create x-rays.

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Cathode

Negative side of the x-ray tube, containing the filament.

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Anode

Positive side of the x-ray tube, containing the target.

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Thermionic emission

Process where a heated filament releases electrons.

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Rotating Anode

Anode that spins, distributing heat, increasing x-ray production.

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Actual Focal Spot

Physical area on the target that electrons hit.

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Effective Focal Spot

Projected area of the x-ray beam.

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Bremsstrahlung Interactions

Energy loss by electrons when interacting with atomic nuclei.

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Off-focus radiation

X-rays generated outside the intended focal spot.

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Radiographic Rating Chart

Chart that specifies safe technical factors for x-ray tube operation.

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Anode Cooling Chart

Chart that specifies time needed for anode cooling before further exposures.

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Characteristic interactions

Occur when high-energy x-rays interact with inner-shell electrons in the patient, causing the ejection of an inner-shell electron.

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Sources of radiation

Radiation can be natural (from the Earth and space) or man-made (from medical devices or nuclear activities).

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Radiation groups

Radiation can be categorized as particulate (high-energy particles) or electromagnetic (photons like x-rays).

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Particulate radiation

High-energy particles that produce ionization directly through atomic collisions.

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Particulate types

From radioactive decay, alpha and beta particles are two types.

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Alpha particles

High-energy helium nuclei with large mass, traveling a short distance (max 5cm) in air.

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Beta particles

Light particles, smaller than alpha particles, traveling farther (10-100 cm) in air.

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Photon interaction result

Photon interactions with matter cause energy transfer through excitation (electron jump) and ionization (electron loss).

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Exposure

The amount of ionization in a given quantity of air.

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Absorbed dose

The amount of radiation energy absorbed by the patient.

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Equivalent Dose

Quantity of radiation received by a radiation worker, considering types of radiation

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ALARA

The basic principle of radiation protection, aiming to keep radiation as low as reasonably achievable

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Personnel Monitoring

Devices used to track radiation workers' exposure, ensuring they don't surpass radiation limits.

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Coherent Scattering

A photon interacts with an electron, causing it to be re-emitted at a different angle, while maintaining the initial energy, frequency, and wavelength.

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Photoelectric Absorption

A photon interacts with an inner shell electron, ejecting it from the atom, and the photon is absorbed.

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Characteristic Cascade

An electron from an outer shell replaces the inner shell electron, emitting characteristic X-rays as it does so.

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Secondary radiation

Radiation produced outside the x-ray tube due to interactions of the primary beam with matter.

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Compton Scattering

A photon interacts with a loosely bound outer shell electron, transferring some energy to the electron and thus changing its direction.

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Scatter Reduction Methods

Techniques to minimize scattered radiation, including beam restriction and grids.

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Collimator

The common beam restricting device in radiography.

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Penumbra Reduction

Bottom shutters of the collimator reduce the unsharpness/blurring of the image.

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Grid Ratio

The ratio of the height of grid strips to the distance between them.

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Grid Frequency

Number of grid lines per inch or centimeter.

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Image Contrast

The difference between adjacent shades of gray.

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Spatial Resolution

Sharpness of detail in an image.

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Quantum Mottle

Image noise caused by insufficient x-ray photons.

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Magnification

A type of distortion related to SID (Source-to-Image Distance) and OID (Object-to-Image Distance).

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Elongation

A shape distortion caused by improper tube angulation.

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Histogram

A graphical representation of the distribution of pixel values (brightness) in an image. It helps determine the range of signal values in a specific region of interest (ROI).

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Rescaling

A process that adjusts the brightness of an image by stretching or compressing the pixel values. This helps correct underexposure or overexposure.

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Look Up Table (LUT)

A pre-defined table in computer systems that maps input pixel values to output pixel values, adjusting contrast and brightness.

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Windowing

A technique for changing the contrast and brightness of an image on the monitor.

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Window Level

A control that adjusts the brightness of the image on the monitor.

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Window Width

A control that adjusts the contrast (difference between light and dark areas) of the image on the monitor.

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Local Processing

Image processing technique where calculations are applied to small groups of pixels (neighborhoods) within an image.

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Kernel

A mathematical code used in local processing to filter data by applying weights to pixels in a neighborhood.

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Masking

A process used in local processing where a kernel is applied to filter image data.

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High Pass Filtering

A type of filtering that amplifies or deletes all but high frequencies in an image, enhancing edges and sharpening details.

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Low Pass Filtering

A type of filtering that reduces or eliminates high frequencies in an image, resulting in smoother edges and reduced noise.

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Geometric Processing

A type of image processing that changes the position or orientation of pixels in an image, such as scaling, rotation, or translation.

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Low Contrast Resolution

The ability to distinguish small differences in signal values (brightness) in a dataset.

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Detective Quantum Efficiency (DQE)

The efficiency of a system (e.g., an IR detector) in converting incoming radiation into an image signal.

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Study Notes

SI Units

  • Standard units of measurement are length, mass, and time
  • Mass is the amount of matter in an object, measured in kilograms
  • Length is the distance light travels in a vacuum in 1/299792485th of a second, measured in meters
  • Time is measured in seconds, relating to vibrations of cesium
  • SI units were adopted by the 11th General Conference of Weights and Measures.
  • There are 7 base SI units.

Matter and Energy

  • Matter is the substance of all physical objects, has shape, form, and occupies space.
  • Mass is the quantity of matter in an object.
  • Weight is the force of gravity acting on an object.
  • Substances have definite and constant composition.
  • Elements are substances that cannot be broken down.
  • Compounds are substances that can be broken down.
  • The smallest particle of an element is an atom.
  • The smallest particle of a compound is a molecule.
  • Einstein's theory of relativity states matter and energy cannot be created or destroyed but can be converted from one to the other (E=mc²).

Atoms and Elements

  • Z number is the number of protons in an atom, determining element classification.
  • Changing the Z number changes the element.
  • Changing the number of neutrons or electrons causes ionization, not a change in element, but can disrupt metabolic relationships.
  • Atomic mass number is the total mass of protons and neutrons in an atom.
  • Valence is an element's combining ability.

X-Ray Tube Components

  • X-ray tubes (Coolidge tubes) are inefficient, producing 1% x-rays and 99% heat.
  • Cathode is the negative side, containing the filament.
  • Anode is the positive side, containing the target.
  • Filament is composed of thoriated tungsten.
  • Dual focus filaments allow for better resolution with small filaments and high heat with large filaments.
  • A focussing cup surrounds the filament.
  • Thermionic emission occurs when electrical energy heats the filament.
  • Anodes are either stationary or rotating.
  • Stationary anodes use tungsten alloy embedded in a copper anode.
  • Rotating anodes use tungsten rhenium alloy for increased heat capacity (300x).
  • Target is where electrons collide, causing x-ray production.
  • Actual focal spot is the physical area hit by electrons.
  • Effective focal spot is the projected area of the x-ray beam.
  • Focal spot size and target angle influence effective focal spot size (inverse relationship).
  • Stator is a bank of electromagnets.
  • Rotor is made of ferromagnetic bars, connected to the anode by a molybdenum stem.
  • Target interactions (bremsstrahlung and characteristic) occur close to the target surface (0.25 - 0.5 cm).
  • Bremsstrahlung interactions are major component of x-ray production.
  • Characteristic interactions involve inner shell electrons.
  • Off-focus radiation is not produced at the focal spot.

Image Quality and Radiation Safety

  • Filtration removes low-energy x-rays (inherent and added).
  • Total Filtration is inherent + added filtration.
  • mAs (milliampere-seconds) controls the quantity of x-rays.
  • kVp (kilovoltage peak) controls the quality of x-rays.
  • Distance and intensity are inversely related (inverse square law).
  • Attenuation is the reduction of photons passing through matter.
  • Photon interactions: Coherent (no change in initial photon, only direction), photoelectric (absorption), Compton (scattering).
  • Beam restrictors (collimators, cones, cylinders) reduce scatter and the primary beam.
  • Grids reduce scatter radiation, but can cause grid cutoff.
  • Grid ratio is the height/distance of grid lines.
  • Filtration and beam restriction are inversely related to exposure.

Image Receptor, Display, and Processing

  • Visibility of detail involves image contrast and spatial resolution.
  • Contrast is the difference in brightness between adjacent areas.
  • Spatial resolution (or frequency) is the sharpness of detail.
  • Quantum mottle is underexposure noise.
  • Noise is expressed as signal-to-noise ratio.
  • Magnification and distortion (elongation/foreshortening) are geometric distortions.
  • Digital radiography uses direct and indirect conversion detectors.

Other Topics

  • Radiation protection principles (ALARA, time, distance, shielding).
  • Radiation sources (natural and man-made).
  • Personnel monitoring devices, radiation protection standards, regulatory agencies.
  • Biological effects (stochastic and deterministic).
  • Image processing in digital imaging (point, local, geometric).
  • Exposure index determines exposure to the image receptor (Digital).

Fluoroscopy and Tomography

  • Fluoroscopy uses high image frame rates for the moving body.
  • Tomography demonstrates coronal sections.
  • Tomography uses synchronized movement of the tube and image receptor.
  • Focal plane reveals the clearest structures.
  • Section interval separates tomographic planes.

CR and DR

  • CR uses phosphor plates in a cassette.
  • DR uses flat panel detectors for direct or indirect electronic conversion.
  • Image acquisition using PSP (phosphor storage plates) or Flat panel detectors .

Image Intensification

  • Image intensification tubes (ITT) increase brightness gain.
  • Input screen converts x-rays into light.
  • Output screen converts electrons into light.
  • Magnification gain is input diameter squared/ output diameter squared.
  • Interrogation and extinction times affect fluoro speed.
  • Image quality (spatial resolution, contrast) significantly influence the use of radiographic and fluoro imaging.

General Concepts

  • Informatics relates to information processing.
  • Platforms and specific medical applications such as Body Mass Index.

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Test your knowledge on the fundamental concepts of the International System of Units (SI) and atomic structure. This quiz covers essential terms, definitions, and equations related to mass, light distance, and atomic properties. Perfect for students seeking a clear understanding of these scientific principles.

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