Sean Marshall Designs Replacement Parts for Human Skulls

By Gabriel Chen, September 2004

Sean MarshallScenario: There has been a car accident. A patient arrives unconscious at the Duke hospital on a stretcher – he has a hole in his skull. The blood has soaked his long, dark hair. His eyes are slits; his stare, distant. A neuro-surgeon tends to him immediately. He calls for a computed tomography scan (also known as a CT scan) of his skull, and sends it to a laboratory in Colorado. There, a model of the head is made, and is relayed back to the hospital. Once the model is received, a sculptor from North Carolina would sculpt to the best of his artistic ability a piece to fill up the defect in the patient’s head. A prosthetist would then take some clay, make a mould out of them, and fill the sculpted piece with the prosthetic material needed before giving it to the surgeon.

The length of the entire process? – Three weeks.

Senior Sean Marshall, who is from Florida, is determined to cut down on the waiting time, which he feels is too long. This summer, he worked at the Duke Biomechanics lab to research cranial malformations and the development of a database of normal cranial indices. His work involved collaboration with a professor of biomechanics, a radiologist, and a plastic surgeon.

"The ultimate goal of my research is for me to design a computer program that would save us money and time by taking the CAT data to create the skull piece that the sculptor sculpts," said Marshall, a biomedical and an electrical engineering major. "We also hope to print out the prosthetics from a 3D printer so as to increase efficiency."

Three-dimensional (3D) printers are already valuable tools for making prototypes of newly designed products. They use lasers to harden thin layers of liquid plastic or to melt and fuse metal or plastic powders to build up three-dimensional forms.

In the future, 3D printers may be able to produce some parts (even complete products) that one might otherwise purchase at a store such as tape dispensers, baseball bats, dinnerware, and picture frames. However, in most cases, it would be impractical to produce these items with 3D printing because a wide variety is already available at inexpensive prices in most discount stores.

Marshall started work at the end of May and is building his computer program from scratch. He will continue to work on his research as an independent study this fall.

Marshall credits the BME department for giving him the necessary resources to carry out his research. For instance, the BME department provided him with the connection to research scientist (ECE) and Adjunct Associate Professor of Computer Science Rachel Brady's Visualization lab. The lab has the software that allows for the visualization and analysis of CT data.

He also has weekly meetings with the Biomechanics lab graduate students and professors. This allows him to get suggestions on how to approach and solve the different problems that he encounters.

Duke's undergraduate BME program was after all one of the chief reasons for his coming here three years ago, he said.

When Marshall was six years old, his grandfather who lived in South Carolina told him about a school down the road called Duke, and that he would be fortunate to end up there some day.

"I had never even heard of it then," chuckled Marshall with fond reminiscence. "But I came to Duke because of its excellent BME program. It helps that the campus is beautiful too. Every day, I walk from my Central Campus apartment through the gardens to get to class, and admire the scenery at the same time. During exam week in spring semester, everybody’s out there studying and getting their pre-tans for Myrtle Beach. It’s so lovely."

Marshall said his favorite class at Duke had to be the one on linear system theory. He learned about signal representations and system response, the Fourier series, as well as how to use MATLAB to solve problems.

MATLAB is a tool for doing numerical computations with matrices and vectors. It can also display information graphically.

"It was a practical course," Marshall said. "For our first project, we had to create a WAV tune using MATLAB. I selected the song: My friends over you. Next, I had to use MATLAB to add mathematical functions that would allow me to create this song as a WAV tune. Every student in class had to vote for the best WAV tune, and I ended up getting the most votes!"

As for his future plans, Marshall said that he may do Teach for America for two years before going to law school to specialize in intellectual property law due to his interest in the patenting aspect of devices used in the laboratory.

Marshall wants to do Teach for America "as a form of break" before going back to school, and also get some income while still being able to travel during the summer. But more importantly, he wants to do the program that seeks to eliminate educational inequity nationwide because he loves teaching.

"M y mom is a teacher and that influenced me in a certain way," Marshall said. "Also, during high school, I was an assistant teacher for a class of students who struggled a lot with their class work. I hope to help the less privileged in education."

Since 1990, more than 12,000 individuals have joined Teach for America, committing two years to teach in low-income rural and urban communities. Following this experience, many have become committed leaders in the effort to expand opportunities for all children. Corps members are paid directly by the school districts for which they work and generally receive the same salaries and health benefits as other beginning teachers.

Marshall continued to elaborate on the reasons for his interest in intellectual property law. In the summer of 2003, he worked at the Biophysics lab in the Duke University Eye Center. He helped develop prototypes for an agent that would be applied to fiber optic light guides, and which would allow light to be emitted more diffusively, aiding ophthalmologists in surgery.

While he enjoyed his "first engineering job experience," Marshall said he was more interested in how devices in the lab were patented.

"The particular lab I worked for gets a lot of patents for the devices they make," he said. "While working there, I realized that researching was not something I wanted to do in the future. I was more interested in the patenting aspect of it, and as such, would hope to do intellectual property law."

Marshall said he would miss the company of his friends most when he graduates this fall.

"I met one of my roommates at a football game," Marshall said. "Another I met during freshman year, as we were both dating girls who were roommates. I also have a group whom I got to know through a girl I danced with at a club. I will miss Duke, as a lot of my close friends are here."

Marshall graduated in May 2005.