DESC:FIELD OF INVENTION
The present invention relates to manufacture of dissectible soft whole models of human / animal / plant/ organic source for exploring morphology through sectioning or dissection by a scalpel or such cutting instruments including hacksaw or laser source for purpose of learning/ teaching/ research / surgical planning.

BACKGROUND OF THE INVENTION
Medical education has been based on illustrations, models, and cadaver samples to teach anatomy and working principles of various body subsystems. While illustrations and models are reusable, cadaver models though rich teaching aids, are limited in availability and have low shelf life. They also pose definite health hazard due to their organic origins and need treatment before use.

For long time, anatomical models made of clay have been used as teaching aids. With the advent of plastics, models made of plastic, joined by glue were used. Some sections were made with soft material such as silicon rubber, thermoplastic polyurethane (TPU) in smaller sections for simulations. 3D printing has made fabrication of complex shapes very easy and has been used in making of anatomical models using various technologies: Stereolithography (SLA), standard linear solid (SLS), fused deposition modeling (FDM), Binder Jetting, Polyjet, etc. In all these known processes, the output is hard models and in sections or small parts only. Most 3D printing processes involve creation of supports to print overhanging structures. SLA, FDM, Polyjet all use supports.

SLS technology makes parts out of powder, by a powder bed fusion process and does not need support as powder itself props up the model / over hung feature. SLS with TPU composite is usually used to make bellows and gasket prototypes. They are also used to make custom insoles / footwear accessories.

Drawbacks of the known art:
• The known anatomical models are capable of producing pre-cut sections.
• If whole model if printed, will have support which remains inside the model (figure 5).
• Most are hard material and are not easy to cut using surgical scalpel.
• The processes available are expensive
• Most models are unfit to be cut and not usable for surgery training or such explorations.

There exists an unmet need to develop a model with following features:
• that can be built as a whole;
• that is built without any support;
• that can be made in variable hardness;
• that can have variable hardness within the same whole model;
• that is eeconomical to manufacture;
• that is quick to prepare;
• that can be prepared on-demand;
• such that a patient-specific model can be made from Medical Image data.

The inventors of the present invention have developed an anatomical model with all of the aforementioned benefits and advantages. The anatomical models of the present invention with sintered thermoplastic polyurethane (TPU) possess all of the aforementioned features. The present invention thus provides anatomical model of human organ that are soft and can be dissected to study the internal morphology of the structure/defect that is near-perfect simulation of performing surgery on actual human organs. The present invention provides a simple, convenient and inexpensive method for the preparation of anatomical models. The model of the present invention is thus an indispensable tool for education and spatial exploration within structures.

OBJECTS OF THE PRESENT INVENTION
It is an object of the present invention to provide an anatomical model prepared by selective laser sintering of nylon composite.
It is an object of the present invention to provide an anatomical model prepared by selective laser sintering of thermoplastic polyurethane (TPU).
It is an object of the present invention to provide an anatomical model dissectible with surgical scalpel.
It is an object of the present invention to provide a simple, convenient, reproducible and inexpensive method for the preparation of anatomical models.
It is yet another object of the present invention to provide an anatomical model that is printed by 3D printing.

SUMMARY OF THE PRESENT INVENTION
According to an aspect of the present invention there is provided a soft dissectible anatomical model comprising nylon composite wherein said composite is made by selective laser sintering method and characterized in that the said anatomical model is printed by 3D printing.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1: Models of the prior art-Clay model of the heart.
Figure 2: Models of the prior art-plastic model of the heart.
Figure 3: 3D printed model (Binder jetting Process).
Figure 4: 3D printed Model (Photo Polymerization).
Figure 5: 3D Printed model in FDM.
Figure 6: 3D Printed model in Material Jetting.
Figure 7: Pre-sectioned SLS hard Model made in Nylon.
Figure 8: Development of a dissectible anatomical whole model of the present invention.
Figure 9: Process of fixing the parameters.
Figure 10: Model of the present invention, ready for dissection.

DETAILED DESCRIPTION OF THE PRESENT INVENTION
The soft dissectible anatomical model of the present invention is prepared by sintering nylon composite. The nylon composite preferably is TPU.
DICOM data of an abnormality preferably a typical heart defect is collected. The data is processed by image processing to build a digital model of the anatomy. The digital file is printed by selective laser sintering using the flexible composite material. The printed material is cleaned and finished to get the final dissectible part.
The raw material used is TPU-based powder sintered by a laser. The process used is selective laser sintering technique. This is also called as power bed fusion. The process parameters are altered to produce a soft model for dissection by surgical scalpel. The main parameters that are found to influence the softness of the model of the present invention are laser power, powder temperature and scan distance or scan density
According to the most preferred embodiment of the present invention,
A) For a given batch of thermoplastic polyurethane (TPU powder), a set of standard test sample are built with specific parameters.
B) The set is tested by a shore hardness system.
C) The results are tabulated and checked for functional criteria.
D) The best result of build parameter is recorded.
E) With Optimal parameter in hand, the target model is built to get the desired final model.
F) The cycle of A to D is carried out for each new batch of Powder.
G) The rest of the process is as per the standard SLS process.
H) Post processing of the model so built offers new scope to explore.
I) The intra layer powder is removed by Air Blast/ Mechanical vibration.
J) To facilitate better powder removal, few holes may be positioned at appropriate places and are later sealed.

Soft tissue models such as heart, lungs, liver, kidney, brain and the like can be made. The model of the present invention may be colored as appropriate for better communication.
As an embodiment of the present invention, there is provided dissectible heart model for teaching and training in surgical procedures. The process of the present invention produces accurate models of the whole heart using 3D printing. Thus, the method has potential as an alternative to cadaver samples. Further, the models of same defect can be repeatedly built for use in training and teaching. The models are prepared and offered to expert faculty and students for dissection and evaluation.
With the anatomical model of the present invention even the soft tissue such as pericardium can be prepared and dissected with surgical scalpel thereby simulating heart surgical procedures.
Computerized tomography (CT data set representing 6 typical congenital heart defect cases was collected from DICOM (Digital imaging and communications on Imaging). The DICOM data set are processed on Materialise Mimics Software to construct a digital model of the part. The digital 3D model data is exported as Stereolithographic file and is sent for 3D printing. The material used is Nylon composite. Selective Laser Sintering is chosen as 3D printing process to build the whole model.
First set of 6 typical sets of congenital heart whole models are successfully made by 3D printing. The models are offered for dissection to expert faculty.
A second 6 sets of same models are offered to students. The 3D heart models were built and dissections carried out.
The results drawn by expert faculty and student demonstrate that the anatomical models of the present invention enabled better teaching as well as learning experience. The 3D printing of dissectible heart model, therefore have potential as an alternative to cadaver sample and can be repeatedly printed to simulate the same defect condition which is very useful to train junior surgeons about the defect morphology.
The anatomical model of the present invention is derived from a specific patient.
The anatomical model of the present invention:
• used for education and training purposes in Art, Engineering and Medicine;
• used for visual impaired for learning through tactile feel;
• is of plant for botanical teaching and research;
• is of animals for Zoology/ Veterinary teaching and research;
• are engineering components that needs sectional explorations for teaching and research;
,CLAIMS:1. A soft dissectible anatomical model comprising nylon composite wherein said composite is made by selective laser sintering method and characterized in that the said anatomical model is printed by 3D printing.
2. The soft dissectible anatomical model comprising nylon composite as claimed in claim 1 wherein the nylon composite is thermoplastic polyurethane.

3. The soft dissectible anatomical model comprising nylon composite as claimed in claim 1 is derived from a specific patient.

4. The soft dissectible anatomical model comprising nylon composite as claimed in claim 1 is for education and training purposes in Art, Engineering and Medicine.

5. The soft dissectible anatomical model comprising nylon composite as claimed in claim 1 is for visual impaired for learning through tactile feel.
6. The soft dissectible anatomical model comprising nylon composite as claimed in claim 1 is of plant for botanical teaching and research.
7. The soft dissectible anatomical model comprising nylon composite as claimed in claim 1 is of animals for Zoology/ Veterinary teaching and research.

8. The soft dissectible anatomical model comprising nylon composite as claimed in claim 1 are engineering components that needs sectional explorations for teaching and research.