Page 185 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

184 CHAPTER 8 Ultrasound applications in cancer therapy

FIGURE 8.2 The ultrasound absorption in different tissues.

cell division. Transmission of ultrasound waves from tissues and organs can lead to
chemical reactions, physical and biological changes. Today, many applications of
ultrasonic waves have been proposed. The use of acoustophoresis technology for
applications such as cell separation [4], cell trapping [5], blood plasma separation,
forensic analysis [6], food analysis, cell sorting and cell synchronization [7], cell
differentiation, and cellular compression. Other sections of the study have been dedi-
cated to diagnosis of diseases and the study of organs by ultrasound imaging. In the
ultrasound imaging, probability of pregnancy, size and sex of the fetus, the appear-
ance of tumors and cysts, the internal structure of the heart, kidney stones, prostate
cancer, thyroid gland, and fluid accumulation in the lung are examined. Increasing
blood flow, muscle cramps decrease, fibroblast stimulation, increased protein pro-
duction, increased tissue regeneration, and bone repair are some of therapeutic appli-
cations of ultrasonic waves. Ultrasonic surgeries are mainly used for cutting soft
tissues (by using the thermal effect) and destroying hard tissues, by centralized ultra-
sonic force. Other ultrasonic applications are; drug delivery, gene and DNA transfer
[8]. The working frequencies, the power, and pressure of the ultrasound waves in
medical applications are shown in Table 8.2 [9].
Medical ultrasound divided into two categories: diagnostic and therapeutic. A
noninvasive diagnostic technique used to image inside the body is called diagnostic

Table 8.2 Different frequencies in medical applications of ultrasound.
Moderate intensity Maximum
2
Application Frequency (MHz) (W/cm ) Pressure (MPa)
Sonography mode B 1–15 Less than 1 0.45–5.5
Sonography mode M 3–10 0.3 More than 4
Echo 3–7.5 1 2.5
Physiotherapy 1 1 Less than 0.5
Lithotripsy 0.5–1 Few More than 20
cutting soft tissues 0.25 Few 5–30
Highly focused 0.5–5 1000–10,000 10
ultrasound waves
Bone repair 1.5 0.03 0.05
Drug delivery 2 Variable 0.2–8