Page 188 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

8.2 Approved modes for ultrasound therapy 187

Table 8.3 A list of therapy applications with FDA approved.
Therapeutic Bioeffect
Therapy method Frequency outcome mechanism
Unfocused beam 1–3 MHz Tissue warming Heating
Hyperthermia 1–3.4 MHz Cancer therapy Regional heating
HIFU 0.5–2 MHz Uterine fibroid Thermal lesion
ablation
4 MHz Laparoscopic tissue Thermal lesion
ablation
3.8–6.4 MHz Laparoscopic or Thermal lesion
open surgery
4.6 MHz Glaucoma relief Permeabilization
Focused ultrasound 4.4–7.5 MHz Skin tissue Thermal lesion
tightening
Extracorporeal ∼ 150 kHz Kidney stone Mechanical stress,
lithotripsy comminution cavitation
Intracorporeal 25 kHz Kidney stone Mechanical stress,
lithotripsy comminution cavitation
Extracorporeal shock ∼ 150 kHz Plantar fasciitis, Unknown
wave epicondylitis
Phacoemulsification 40 kHz Lens removal Vibration, cavitation
US assisted 20–30 kHz Adipose tissue Fat liquefaction,
liposuction removal cavitation
Tissue cutting and 55.5 kHz Laparoscopic or Thermal lesion,
vessel sealing open surgery vibration
Intravascular US 2.2 MHz Thrombus Unknown, gas
dissolution body activation
Skin permeabilization 55 kHz Transdermal drug Unknown
delivery
Low-intensity 1.5 MHz Bone fracture Unknown
pulsed US healing

8.2.1.1 Physical therapy
Unfocused beams of ultrasound for physical therapy were the first clinical applica-
tion, dating to the 1950s, which often has been referred to simply as “therapeutic
ultrasound” [14]. This modality now typically has a base unit for generating an elec-
trical signal and a hand-held transducer. The hand-held transducer is applied with
coupling gel and moved in a circular motion over an injured or painful area of the
anatomy to treat conditions such as bursitis of the shoulder or tendonitis, by trained
physical therapy technicians. The objective is to warm tendons, muscle and other
tissue to improve blood flow and accelerate healing. Ultrasound application can also
assist by promoting transport of the compound into the skin, a method sometimes
called sonophoresis or phonophoresis (as opposed to electrophoresis) [15]. Drugs
such as lidocaine or cortisol have been used extensively in sports medicine. The
level of clinical benefit to the patient from physical therapy ultrasound treatments