Page 29 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

26 CHAPTER 2 Diagnostic imaging in cancer

hydrophilic molecules due to the fast-renal excretion. In order to improve the sensi-
tivity of X-ray scanners, high dose molecules need to be administrated which may
cause acute renal toxicity, cardiovascular problems, and allergy. To deal with the
problem, a new class of lipid-based radiopaque CT has been introduced to replace
hydrophilic iodinated CAs such as Lipiodol [7] and Fenestra [8]. Furthermore, nano-
technology brings new types of radiopaque CT to the market [9].
Recent progress in technology develops new applications for the use of CT, such
as parasite imaging [10], coronary inflammation [11] and determining the initial
breast tumor size [12].

2.1.3 Advantages and disadvantages

The main consideration of using X-ray imaging technic is related to an assessment
of benefit-to-risk profile.
The key advantages of this technic include:
1. Easy and quick processing
2. Having high resolution
3. Be able to diagnosis various kinds of diseases including broken bone, infection,
and cancer

The main limitation of this technic ise as follow:
1. Causing genetic damage due to the delivery of high dose
2. Causing nephropathy and cardiovascular problems
3. Inducing cancer or increasing cancer life time
4. Costly

It should be noted that all these side effects depend on the amount of photon
energy, number of scan and scan speed [13]. The damages are minimized by com-
promising the quality of the image and patient health.

2.2 Magnetic resonance systems

For many decades, there has been an opinion that magnetic field passes through the
body with no harmful effects [14]. Since then, the application of magnetic field in
biomedicine has been introduced. Magnetic resonance imaging (MRI) is a nonion-
izing imaging technic providing high resolution 3D-images of soft tissues. Currently,
MRI is one of the most well-known tools for human visualization [15]. It mostly has
been used for tumors detection, brain, and cardiovascular observation.

2.2.1 Principle
MRI provides images based on the relaxation times (transvers T and longitudinal
2
T ) of water in a magnetic field. In body, each compartment has been surrounded
1