Abstract:

This paper evaluates the parameters affecting the quality of 3D printed models from CT (computed tomography) scans of human bones and organs. A CT scan combines a series of X-rays from different angles around the body and uses software to create cross-sectional images (slices) of bones and organs. The two CT scans in this study were from an 80 year old female. The reconstructed data from one of the CT scans with no IV contrast agent had a slice thickness of 3.75mm and from the second CT scan with an IV contrast agent had slice thicknesses of 2.50mm and 0.98mm. 3DSlicer software was used to segment the 3D models from the CT scans. The parameters affecting the quality of 3D printed models that were evaluated in this study were: CT slice thickness, CT IV contrast, 3DSlicer threshold levels, 3DSlicer paint and grow from seeds option and 3DSlicer smoothing methods. Anatomically correct 3DSlicer models were constructed of the spine segments, lungs, trachea, liver, kidneys, aorta, stomach and spleen. The results of the evaluation were: 1) the CT scan with a slice thickness of 3.75mm resulted in excellent 3D printed models of the spine segments, 2) the threshold option in the 3DSlicer segment editor was critical in creating 3D models of the bones, 3) large threshold values resulted in more detail and also more holes in the model while a smaller threshold resulted is less detail and fewer holes in the models, 4) the CT scan with an IV contrast and a slice thickness of 2.50mm resulted in a much sharper model of the spine, however, considerably more effort was necessary to remove the noise and extrusions, 5). it was easy to rapidly 3D print the lungs and trachea from the CT scan a slice thickness of 3.75mm since the area surrounding the lungs was lighter in color, and 6) a CT with an IV contrast agent and a small slice thickness (2.5mm or 0.98mm) were necessary for printing the other organs. The results of this study are being implemented into the Simulation Based Learning Experiences (SBLEs) by the College of Nursing at the University of Alabama in Huntsville. SBLEs are an array of structured activities that represent actual or potential situations in education and practice. These activities allow participants to develop or enhance their knowledge, skills, and attitudes, or to analyze and respond to realistic situations in a simulated environment. SBLEs occur in a simulation laboratory where nursing students come for a given amount of time to engage in activities specifically designed around a set of learning objectives. These activities are developed into simulation cases with realistic patient scenarios. The College of Nursing has developed over one hundred SBLEs. Each simulated clinical experience is documented in detail and placed in a binder with specific objectives, a detailed set up sheet and pictures for standardized repetition with multiple clinical groups. Three specific 3D printed models (assemblies) have been added to the SBLE's at UAH: 1) kidney with renal arteries/aorta/spine, 2) liver/stomach/spleen, and 3) lungs/trachea. A heart/aorta arch and aorta/spine assembly is currently being developed. All the 3D printed organs and bones in the assemblies are anatomically correct, printed to scale (correct size) and most importantly in the correct location relative to other organs and bones. With 3DBuilder software nursing students can view and rotate and enlarge the models on their own computer.

Keywords:

3 D Printed Models, CT Scan, Anatomical medical models, Training nursing students.