R_Bibb_Medical_Modelling_The_Application_of_Adv.pdf

Case studies 135
create template (30 minutes), planning (one hour), marking of template
(15 minutes) the total time taken is 2.5 hours. This involves at least one
technician, one surgeon and requires a patient appointment which, depending
on salaries and overheads, could represent a cost saving of approximately
£250.
6.3.8 Benefi ts and future development
The principal benefi ts resulting from this approach are reduced cost implications
for planning activities. Once the entities are created from the CT
data, they can be positioned and repositioned as many times as required.
This allows different placement strategies to be performed and evaluated
in three dimensions in a matter of minutes and with zero costs implication
(other than time).
Once a plan has been agreed between the clinicians, the implant sites
themselves can be assessed for bone depth and quality (within the limits of
the original CT scan). If they are found to be unsatisfactory, these sites can
be altered without incurring cost. When a fi nal solution is achieved, the
template model can be made in under two hours and cost dramatically less
than even a localised stereolithography model of the bone structure. The
CT data used in these cases was taken at 1.5 mm slice distance and proved
adequate. However, reducing this slice distance would increase the quality
of the three-dimensional entities.
Of course, the purchase and maintenance of the software required for
this approach is signifi cant, and it can be anticipated that a high volume of
cases would be required to justify this investment in isolation. However,
it is the experience of the authors that such software has many useful
applications in head and neck reconstruction as well as other medical
specialities.
6.3.9 References
1. Klein HM, Schneider W, Alzen G, Voy E D, Gunther RW (1992), ‘Pediatric
craniofacial surgery: comparison of milling and stereolithography for 3D-model
manufacturing’, Pediatric Radiology, 22, 458–60.
2. Bibb R, Brown R (2000), ‘The application of computer aided product development
techniques in medical modelling’, Biomedical Sciences Instrumentation, 36,
319–24.
3. Bibb R, Brown R, Williamson T, Sugar A, Evans P, Bocca A (2000), ‘The application
of product development technologies in craniofacial reconstruction’,
Proceedings of the Ninth European Conference on Rapid Prototyping and
Manufacturing, Athens, Greece, 113–22.
4. D’Urso PS, Redmond MJ (2000), ‘A method for the resection of cranial tumours
and skull reconstruction’, British Journal of Neurosurgery, 14 (6), 555–9.