Page 58 - Flexible Robotics in Medicine

42 Chapter 3

resulting in late detection and diagnosis at an advanced stage 3 or 4. Survival rates
decrease significantly, particularly from stage 3 to 4, where the 5-year survival rates
decrease from 62% to 38% [7]. This is primarily a cause of concern, as early detection
can increase patient survival rates. There is clearly a need for a home-based prototype to
allow easy detection and constant monitoring of the NPC in the comfort of the patients’
homes [10].

A significant percentage of patients are inclined to redevelop NPC following treatment [11].
The median interval between initial treatment and recurrence ranges from 1 month to
10 years. Most subjects experience a recurrence within 3 years of initial treatment, with
48.7% experiencing a recurrence within 2 years [11]. Thisstronglysuggestsa need forclose
monitoring of the nasopharynx after treatment to assist in the detection of recurring NPC as
early as possible. Moreover, as discussed earlier, the distinct ethnicity of NPC points to a
genetic predisposition to NPC. Therefore genetically at-risk subjects can benefit from an early
detection and surveillance prototype for frequent assessment of their condition.

One major problem of current endoscopes is the lack of subject-operated capability, which
eliminates the feasibility of using the prototype in the comforts of the subjects’ homes.
After treatments for NPC have been administered, compulsory follow-up visits to the
hospital are required every few months to a year. However, this can be costly and result in
inconvenience for elderly subjects or subjects with disabilities. Thus there is a need to
improve on the existing endoscopes designs to enable home-based usage in view of these
needs from the consumers.

Therefore we came up with a self-administered prototype for detection and constant
monitoring of the NPC in the comfort of the subjects’ homes, while ensuring the user-
friendliness, affordability, comfort, and safety of the subjects.

3.1.3 Summary of prior art

There is a wide variation in the design of the endoscope flexion mechanism. The focus in
this chapter will be on cable-driven manipulators. Cables exert tension on a body element,
and it is through these tensions that a body member bends. To selectively bend only
constricted regions of the body, constriction members employed are usually stiffer and more
resistant to bending than the bending regions such that localized bending is achieved. Other
than cable-driven mechanisms, other methods employ pressure-driven deflection, shape
memory alloy, or precurved concentric tubing. As these methods have little relevance to the
cable-driven technique, it will not be further elaborated. Cable-driven manipulators can be
subdivided into rigid and flexible manipulators. Rigid manipulators usually include a
plurality of segments that are secured into a serpentine structure via joints. State-of-the-art
rigid endoscopes manipulate designs in the rigid segments. Each individual rigid