Models of the various parts of the body built directly using the CT or MRI data are called Medical Models. The scanned data that is stored in the computer system of the scanning machine is directly used for processing through software and then the same is built on a computer-controlled Rapid Prototyping Machine.

The steps involved in the entire process are as follows :-

	Reading the data from various scanning systems
	Selecting the appropriate region of interest
	Interpolating the data; within a slice and also across the slices
	Converting it to a format that is suitable for the Rapid Prototyping machine
	Transferring the data from the computer to the machine
	Building of the model by the machine

The key benefits of these models can be broadly classified as :

   Visualising the Anatomy : The models provide a very close-to-real information about the condition of the particular anatomical region at the time of scanning. This can be useful for pre-operative planning, communication between professionals of multiple disciplines and for teaching at institutes or special workshops

   Surgery Rehearsals : These models serve as useful dummies for rehearsing the surgical procedures. These can be cut &/or joined in various combinations to verify and ensure that the final result is as expected by the surgeon.

   Developing Custom Implants : As the CT or MRI scan provides very accurate data on the anatomy, the implant developed based on it will also be highly accurate. The ability of making mirrored models on the computer itself, adds to the variousossibilities of working.

The following are required :-

Data on MOD The data (2D images) from the CT or MRI machine on a 5.25” Magneto-Optical-Disk (MOD), preferably a Pioneer DEC-702. 3D reconstruction is not necessary on the scanning system. b) Film of images

One set of print of the images which clearly mention orientations (L, R, A, P, T & B) and the region of interest marked-up on it.

Data from almost all commonly used machines are acceptable. MODs from various models of GE, Siemens, Yokogawa, Elscint, Hitachi etc. are readable. We have already read data from GE’s CT/I & Siemens -Somatom scanners. Please refer to us for any specific scanner that you might have.

Typically the following :-

	Slice intervals between 1 to 3 mm in the region of interest
	No gantry tilt (or if necessary, it should be more than 10 degrees)
	2D Image Data to be saved and given to us on MOD (just the images films are not good enough)
	Adjust the focus so that the dithering of images is avoided.

A scan can be split into multiple regions based on the specific requirement of the case and each of these regions can be built separately.

Each of these models can be subsequently replicated into various types of materials, rigid (transparent or opaque) or flexible (regular, semi- & highly). Such replicas are useful for distributing to attendees of surgical workshops.

The first model that is made is of ABS equivalent plastic. This material is sufficiently strong and does not break under normal handling. A variety of manufacturing/surgical processes can be performed on these e.g. sawing, chipping, drilling, tapping, pasting with glue or screws or tapes etc. Thus making them very useful for surgical rehearsals.

The subsequent replicas can be made of a variety of materials that are castable upto 50degC. There are materials that simulate various grades of plastic or rubber. Besides, the graft material can also be used in the molds that are cast from the first plastic model.

It is the complex cases where the surgeons will find these models to be most useful. Some of the areas where the surgeons have seen the benefits are :

	Orthopaedics	:	Fractures, Dislocation & Deformity, Implants & Graft Preparations
	Cosmetic / Plastic	:	Facial reconstruction
	Neurology	:	Cranioplasty and other Skull deformities
	Oncology	:	Tumour Analysis & Replacements

We are willing to explore other areas of its application as well.