Electrodes in Capacitors and Inductors

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Questions and Answers

What happens to ions when they are in an electrical field?

They change their polarity

They move in a circular motion

They are unaffected

They are attracted or repelled depending on the charge of the pole (correct)

What is a characteristic of capacitor electrodes?

They produce a stronger magnetic field than electrical field

They have uniform contact and spacing equal to cross-sectional diameter of pads (correct)

They are typically used for deep tissue heating

They are made of a ferromagnetic material

What is a precaution when using a capacitor electrode with a high-fat content area?

The electrode should be moved frequently

The patient should be grounded

The electrical field may overheat the area (correct)

The treatment time should be longer

What is the purpose of toweling in a capacitive method?

To ensure uniform contact between the electrode and skin Signup and view all the answers

What is a characteristic of air space plates?

The sensation of heat is directly proportional to the distance from the skin Signup and view all the answers

What is a characteristic of inductor electrodes?

They create a magnetic field by inducing eddy currents Signup and view all the answers

What is the result of passing current through a coiled cable?

It generates heat through eddy currents Signup and view all the answers

Why is the patient not part of the circuit in an induction method?

Because the magnetic field is not directly interacting with the patient Signup and view all the answers

What is a precaution when using an induction method?

The patient may not feel as much heat superficially Signup and view all the answers

What is a characteristic of drum electrodes?

They are used for deep tissue heating Signup and view all the answers

What is the primary purpose of using continuous shortwave and microwave diathermy?

To achieve thermal effects Signup and view all the answers

What is the effect of increased tissue temperature on blood flow?

Vasodilation Signup and view all the answers

Why is it difficult to control the amount of heating in diathermy?

Because the dose of heating cannot be directly measured Signup and view all the answers

What is the formula for heating in diathermy?

Heating= Current2 X Resistance Signup and view all the answers

What is pulsed shortwave diathermy used to treat?

Soft tissue injuries and wounds Signup and view all the answers

What is the frequency of the Shortwave Diathermy Unit that generates a stronger magnetic field?

13.56 MHz Signup and view all the answers

What is the effect of pulsed shortwave diathermy on damaged cells?

Depolarization of damaged cells Signup and view all the answers

What is the purpose of the Power Meter in a Shortwave Diathermy Unit?

To monitor the current from the power supply Signup and view all the answers

What is the effect of pulsed shortwave diathermy on cell division?

Loss of cell division Signup and view all the answers

What is generated by pulsed shortwave diathermy to increase Na pump activity?

A magnetic field Signup and view all the answers

What is the desired temperature range for therapeutic effect in Shortwave Diathermy?

40-45°C Signup and view all the answers

What happens when the patient's circuit oscillates at the same frequency as the device frequency?

The electromagnetic energy is fully delivered Signup and view all the answers

What is the purpose of the Tuning Control in a Shortwave Diathermy Unit?

To tune the output frequency Signup and view all the answers

What is the recommended initial output intensity setting for a Shortwave Diathermy Unit?

30-40% Signup and view all the answers

What happens when the patient is out of resonance in a Shortwave Diathermy Unit?

The power output decreases Signup and view all the answers

What is the purpose of the Power Amplifier in a Shortwave Diathermy Unit?

To amplify the power to drive the electrodes Signup and view all the answers

What is the recommended final output intensity setting for a Shortwave Diathermy Unit?

50% Signup and view all the answers

What is the purpose of the Radio Frequency Oscillator (RFO) in a Shortwave Diathermy Unit?

To generate the radio frequency oscillations Signup and view all the answers

What is the primary characteristic of high-frequency modalities, including short wave diathermy?

They use radiation with more than 1 million cycles per second Signup and view all the answers

What is the effect of short wave diathermy on motor or sensory nerves?

It does not stimulate either motor or sensory nerves Signup and view all the answers

What is the primary mechanism by which short wave diathermy produces heat?

Through the resistance in body tissues Signup and view all the answers

What is the effect of short wave diathermy on tissue cells?

It produces heat as it is absorbed by the tissue cells Signup and view all the answers

What is the characteristic of the impulses of short wave diathermy?

They have a short duration Signup and view all the answers

What is the characteristic of short wave diathermy in terms of its mode of operation?

It can be either continuous or pulsed Signup and view all the answers

Study Notes

Capacitor Electrodes

Create a stronger electrical field than magnetic field
Ions are attracted or repelled depending on the charge of the pole
Electrical field is the lines of force exerted on charged ions that cause movement from one pole to another
Center has higher current density than periphery
The tissue that offers the greatest resistance to current flow develops the most heat
Fat tissue resists current flow, thus fat is heated in an electrical field

Air Space Plate Electrodes

Sensation of heat is in direct proportion to the distance of the electrode from the skin
Closer plate generates more surface heat
Parts of the body low in subcutaneous fat are best treated
Greater electrical field is produced
Patient is part of the circuit
Uniform contact is required (toweling)
Spacing equal to the cross-sectional diameter of pads is necessary
Part to be treated should be centered
Increasing the spacing will increase the depth of penetration but will decrease the current density

Capacitive Method

Good for treating superficial soft tissues
Creates a stronger electrical field than magnetic field

Inductor Electrodes

Creates a stronger magnetic field than electrical field
A cable or coil is wrapped circumferentially around an extremity or coiled within an electrode
Passing current through a coiled cable creates a magnetic field by inducing eddy currents (small circular electrical fields) that generate heat
Patient is not part of the circuit
Greatest current flow through tissue with the least resistance
Tissues react like a parallel circuit
Fat does not provide as much resistance to electromagnetic energy
Tissue high in electrolytic content responds best to a magnetic field (muscle and blood)

Induction Method

Not as much superficial sensation of heat with electromagnetic energy
Precaution: electrical field may overheat area with large fat content

Treatment Time

Typically, SWD treatments last for 20-30 minutes
As skin temperature rises, resistance falls

Diathermy

Considered to be high-frequency modalities because they use radiation with more than 1 million cycles per second
Impulses of such short duration come in contact with human tissue, there is insufficient time for ion movement to take place
Consequently, there is no stimulation of either motor or sensory nerves
The energy of this rapidly vibrating radiation produces heat as it is absorbed by tissue cells, resulting in a temperature increase
Shortwave diathermy may be either continuous or pulsed

Physiologic Responses to Diathermy

Tissue temperature increase
Increased blood flow (vasodilation)
Increased venous and lymphatic flow
Increased metabolism
Changes in physical properties of tissues
Muscle relaxation
Analgesia

Non-Thermal Effects of Diathermy

Used to treat soft tissue injuries and wounds
Related to depolarization of damaged cells
Loss of cell division
Loss of proliferation
Repolarization corrects cell dysfunction
Generates a magnetic field to increase Na pump activity

Shortwave Diathermy Unit

Radio transmitter assigned frequencies (27.12 MHz, 13.56 MHz, 40.68 MHz)
Generates both an electrical and a magnetic field
Ratio depends on characteristics of both the generator and the electrodes
SWD units at 13.56 MHz = stronger magnetic field
SWD units at 27.12 MHz = stronger electrical field

Power Output

Should provide energy to raise tissue temperature to the therapeutic range (40-45°C) (80-120 watts)
Should exceed SAR (specific absorption rate) - the rate of energy absorbed per unit area of tissue mass

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Description

This quiz covers the basics of electrodes in capacitors and inductors, including their selection and how they influence treatment. It also explores how they interact with electrical and magnetic fields.