NPTE-PTA Therapeutic Modalities and Electrotherapy

Question 1

Which parameter determines the frequency of ultrasound and affects depth of penetration?

Accepted Answer

Frequency (MHz)

Answer

Ultrasound at 1 MHz penetrates deeper (up to 5 cm) and is used for deep tissues, while 3 MHz penetrates more superficially (1–2 cm) due to higher absorption.

Question 2

What does a 20% duty cycle in pulsed ultrasound indicate?

Accepted Answer

Ultrasound is on 20% of the time and off 80% of the time

Answer

Duty cycle is the ratio of on-time to total cycle time; a 20% duty cycle means the ultrasound is active for 20% of each pulse cycle, reducing thermal effects.

Question 3

Which electrical stimulation waveform is most commonly used for muscle strengthening in a normally innervated muscle?

Accepted Answer

Russian current (medium-frequency AC)

Answer

Russian current (2500 Hz sinusoidal AC delivered in 50 bursts/sec) is widely used for muscle strengthening because it produces strong, comfortable muscle contractions.

Question 4

What is the primary physiological effect of cryotherapy in the first 24–48 hours post-injury?

Accepted Answer

Vasoconstriction, reduced metabolism, and decreased edema formation

Answer

Cryotherapy causes vasoconstriction, slows cellular metabolism, and reduces the release of inflammatory mediators, limiting secondary tissue damage in the acute phase.

Question 5

Iontophoresis uses which principle to drive medication through the skin?

Accepted Answer

Direct electrical current repelling similarly charged ions

Answer

Iontophoresis uses direct current to drive ionized medication through the skin; like charges repel, so a negatively charged drug is driven from the negative electrode into tissue.

NPTE-PTA - National Physical Therapy Examination for Physical Therapist Assistants Practice Test

NPTE-PTA - National Physical Therapy Examination for Physical Therapist Assistants Practice Test

NPTE-PTA Therapeutic Modalities and Electrotherapy