PAM Ultrasound & Phonophoresis 3 — Questions and Answers
Question 1: When selecting ultrasound parameters for an acute inflammatory condition, the MOST appropriate setting is:
- Continuous mode, 1.5 W/cm², 1 MHz
- Pulsed mode (20%), 0.5 W/cm², 3 MHz (Correct answer)
- Continuous mode, 2.0 W/cm², 3 MHz
- Pulsed mode (50%), 1.5 W/cm², 1 MHz
Correct answer: Pulsed mode (20%), 0.5 W/cm², 3 MHz
Pulsed mode minimizes thermal effects while low intensity and 3 MHz limit penetration to superficial inflamed tissue, making it safe for acute conditions.
Question 2: The effective radiating area (ERA) of an ultrasound transducer refers to:
- The total face area of the transducer head
- The area that produces clinically significant acoustic output (Correct answer)
- The depth of tissue treated per treatment session
- The ratio of peak to average intensity
Correct answer: The area that produces clinically significant acoustic output
ERA is the portion of the transducer face that actually emits therapeutic acoustic energy, typically smaller than the total transducer face.
Question 3: Which medication is most commonly used for phonophoresis in the treatment of musculoskeletal inflammation?
- Lidocaine 4%
- Hydrocortisone 1% (Correct answer)
- Capsaicin 0.025%
- Diclofenac 3%
Correct answer: Hydrocortisone 1%
Hydrocortisone 1% cream is the most widely studied and commonly used agent for phonophoresis targeting musculoskeletal inflammation.
Question 4: The spatial average temporal average (SATA) intensity is used to:
- Determine the transducer's effective radiating area
- Describe average power output over time and space (Correct answer)
- Measure peak intensity at the beam's center
- Calculate duty cycle of pulsed ultrasound
Correct answer: Describe average power output over time and space
SATA intensity represents the average intensity both across the beam's cross-section and averaged over the pulse cycle, indicating overall energy delivery.
Question 5: An ultrasound transducer should be moved continuously during treatment primarily to:
- Maximize energy absorption at the target tissue
- Prevent hot spots from standing wave formation (Correct answer)
- Reduce impedance mismatch at tissue interfaces
- Increase cavitation throughout the treatment area
Correct answer: Prevent hot spots from standing wave formation
Continuous transducer movement prevents standing waves that can create dangerous focal areas of high intensity (hot spots) in tissue.
Question 6: Ultrasound is contraindicated over the gravid uterus because:
- It causes fetal tachycardia
- Thermal and cavitation effects may harm developing fetal tissue (Correct answer)
- It deactivates placental enzymes
- The fluid medium amplifies intensity beyond safe levels
Correct answer: Thermal and cavitation effects may harm developing fetal tissue
Thermal and cavitation effects of ultrasound on rapidly dividing fetal cells pose unacceptable developmental risk, making the gravid uterus an absolute contraindication.
Question 7: The primary difference between acoustic streaming and microstreaming is:
- Acoustic streaming occurs at cellular level; microstreaming is bulk fluid movement
- Acoustic streaming is bulk fluid movement; microstreaming occurs near cavitation bubbles (Correct answer)
- Acoustic streaming is a thermal effect; microstreaming is a mechanical effect
- They are synonymous terms for the same phenomenon
Correct answer: Acoustic streaming is bulk fluid movement; microstreaming occurs near cavitation bubbles
Acoustic streaming refers to unidirectional bulk fluid movement induced by the sound beam, while microstreaming occurs in the fluid immediately surrounding oscillating cavitation bubbles.
PAM Ultrasound & Phonophoresis 3
When selecting ultrasound parameters for an acute inflammatory condition, the MOST appropriate setting is: