Electrostatics and Magnetism Quiz

Imaging Equipment and Maintenance

• This presentation covers imaging equipment and maintenance.
• The presenter is Rafael Santos, RRT, faculty at Lyceum-Northwestern University's College of Radiologic Technology.

Basic Circuitry

• A pre-test on basic circuitry is included in the presentation.

Pre-Test Questions

• Question 1: What is the rate of charge flow?
• Correct answer: Current
• Question 2: What is the difference in charge between two points?
• Correct answer: Voltage
• Question 3: What is the smallest magnet?
• Correct answer: Electron
• Question 4: What is a substance with many free electrons and low resistance called?
• Correct answer: Conductor
• Question 5: What is the SI unit of power?
• Correct answer: Watt
• Question 6: What does the resistance of a conductor vary inversely with?
• Correct answer: Area of cross-section
• Question 7: How does temperature affect resistance?
• Correct answer: Resistance increases as temperature increases
• Question 8: What happens when like charges meet?
• Correct answer: They repel
• Question 9: What does not permit the flow of electricity?
• Correct answer: Insulator
• Question 10: What device measures potential difference?
• Correct answer: Voltmeter

Electricity

• Electricity is a form of energy created by moving electrons and other subatomic particles.
• Dr. William Gilbert coined the term "electrica."
• Electricity encompasses various phenomena caused by electric charge presence and flow.
• Electrostatics studies stationary electric charges.
• Electrodynamics studies electric charges in motion and deals with electric current.
• Electrification is the transfer of electrons from one object to another.
• Electric potential is the ability of a system to do work as it releases stored energy.
• Electric current is the flow of electricity through a conductor (measured in amperes).
• Static charge develops from friction (e.g., rubbing amber).
• Current flow is from positive to negative.
• Electron flow is from negative to positive.
• Current is measured in amperes (amps).

Electrostatic Law

• Like charges repel; unlike charges attract.
• Coulomb's Law: The force of attraction or repulsion between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance separating them.
• Electric charge concentration: Electric charge of a conductor is concentrated along the sharpest curvature of the surface.
• Electric charge distribution: Electric charge distribution is uniform throughout the surface of a conductor.

Electric Classification of Matter

• Conductors allow electron flow (e.g., copper, gold, aluminum).
• Insulators inhibit electron flow (e.g., plastics, rubber).
• Semiconductors can act as either conductors or insulators (e.g., silicon, germanium).
• Superconductors allow the flow of electrons even without voltage (very cold required.)

Ohm's Law

• Total voltage across a circuit equals the product of total current and total resistance.
• Voltage is measured in volts (V).
• Current is measured in amperes (A).
• Resistance is measured in ohms (Ω).
• V = I x R (Voltage = Current x Resistance).
• I = V / R (Current = Voltage / Resistance).
• R = V / I (Resistance = Voltage / Current).

Electric Circuit

• A series circuit connects circuit elements in a line along a conductor and the same current flows through every part.
• A parallel circuit connects circuit elements at their ends rather than in a line. Each element receives full voltage.
• Electrical components have different symbols.
• A complete circuit is required for continuous electron flow.

Transformers

• Transformers change alternating voltage and current intensity via mutual induction.
• Transformers convert low voltage to high voltage, or vice versa.
• Transformers don't change energy form.
• Transformers have a primary and secondary coil, electrically insulated from each other.
• Transformer types include step-up and step-down.
• Turns ratio: primary coil turns / secondary coil turns.
• Transformers have core constructions i.e., air-core, open core, and closed core, etc.

X-Ray Imaging System

• Components of an X-ray imaging system include the X-ray tube, operating console, and high-voltage generator.
• The operating console controls the X-ray tube current and voltage.
• Radiation quantity is the number of X-rays (expressed in mGy/mAs).
• Radiation quality refers to X-ray beam penetrability (expressed in kVp).
• Most systems operate on 220 V.

Line Compensating Device

• A line compensator adjusts the incoming voltage to precisely maintain 220 V.
• The voltage variations are typically ±5%.
• Autotransformers are used in the line compensator circuit.

Autotransformer

• Autotransformers have one winding and are essential in X-ray imaging systems, primarily to supply voltages of varying magnitude.

KVP Adjustment

• The console knobs adjust the transformer taps for major or minor kVP.
• Advanced units have a LED readout of kVP.

mA Control

• The mA selector controls the tube current (measured in milliamperes), which in turn determines the number of electrons emitted from the filament.
• The filament circuit and transformer are used in the process.

High-Voltage Circuits

• High-voltage circuits energize the X-ray tube.
• Step-up transformers are significant for raising the voltage output from a few hundred volts to tens/hundreds of thousands of volts.

X-Ray Control Panel

• The panel is used to adjust technical factors and controls the x-ray machine operation.
• Typical controls include mA (or mAs), kVp, focal spot settings, an expose button and voltage compensation.

Image Intensified Fluoroscopy

• Image intensifiers are electronic vacuum tubes that improve image brightness by converting x-rays to light, then back to electrons.
• Image intensifiers have five major parts: the input phosphor, photocathode, electrostatic focusing lenses, accelerating anode, and output phosphor.

Cineradiography

• A technique for producing motion picture records using radiographs.

Digital Fluoroscopy

• Digital fluoroscopy systems convert analog video signals to digital data.
• Essential components include camera (CCD), ADC, DAC, memory, and computer.

Digital Subtraction Angiography

• DSA is a technique that requires complex equipment to process a number of pulsed images to produce subtracted images.
• It uses pre-contrast images as a mask.

Dental X-Ray Unit

• Dental X-rays use low radiation levels to capture details of the teeth and gums
• Used for oral health assessments.

Bone Densitometer

• A test similar to an X-ray to quickly and accurately measure bone density.
• Used mainly for osteopenia or osteoporosis diagnoses.

Mammography Unit

• This unit compresses the breast for detailed images of the tissue.

Radiograph Processing (Processing System Tanks)

• Automatic processors use specialized tanks (developer, fixer, wash, and dryer) for film.
• Manual processors use tanks for processing, typically with a master and insert tank for chemical storage.

Automatic Processor

• Crucial components include a roller transport system, processing cycle, processor capacity, feed tray, entrance rollers, planetary rollers, turn-around/solar/master roller, crossover roller, squeegee roller, and guide plates or shoes.
• Replenishment and recirculation systems maintain appropriate chemical levels.
• A temperature control system preserves ideal temperature conditions.
• A drying system regulates humidity for high-quality film.

Other

• Different types of x-ray equipment like X-ray tube stand exist.
• Mobile X-ray units allow radiographic imaging without moving patients.