It's distressing enough for anyone to learn that he has a brain tumor without the additional information that available treatment is long, cumbersome and prone to inaccuracy.
For the neurosurgeon, small inaccuracies in hardware placement could mean major problems during surgery. Stereotactic radiosurgery (SRS) is a treatment for metastatic brain tumors as well as a wide variety of other diseases. It involves the delivery of a high dose of radiation to a lesion, or area of diseased tissue, from many different directions.
SRS usually requires the use of a stereotactic frame that is fixed onto the patient's skull to ensure accurate targeting of the radiation.
Eric Ford, an assistant professor in the Department of Radiation Oncology and Molecular Radiation Sciences at Hopkins, along with several other doctors and students, has addressed the problem of neurosurgeons being unable to "see inside the brain" during frame placement in SRS with a new technology, a computerized "virtual" frame.
"The virtual frame came out of a need in our clinic to more precisely locate the frame with respect to the internal lesion in the brain. The problem is that there is no way for the neurosurgeon to 'see inside' the brain as they are placing the frame. So we set out to develop a way to plan where the frame would go," Ford said.
The team ran into problems while trying to decide how to best address the frame placement problem. They originally considered developing additional physical tools to use in the operating room, before deciding on a simpler computer-only solution.
"We briefly considered adapting some intra-operative navigational tools, but wanted something that was simpler with less technology overhead. The computer-only solution seemed ideal. About this same time, we had an undergraduate student, David Purger, come down for the summer from MIT. We sicced him on it, and he got more done in the first two weeks than I thought he would over the entire summer. That really kick started the project, and?after a year of software development we had something that works in the clinic," Ford said.
The resulting software is a virtual frame, or a computer representation of the stereotactic head frame that is used in surgery and allows the surgeon to predict the position of the frame in relation to an MRI scan. The overlay of the virtual frame on the MRI scan using the program allows the surgeon to determine the best location for the frame prior to SRS.
The virtual frame works by using a three-dimensional representation of all the hardware parts of the frame to superimpose on the MRI scan. These parts can be manipulated in the program.
The paper indicates that the software is quite exact, with an initial study suggesting accuracy within less than three millimeters compared to previous surgeries. Additionally, the team has shown that initial clinical use on patients indicates an average discrepancy of the virtual frame location and the actual frame location of less than one millimeter.
Radiosurgical treatment planning software can generate an initial treatment plan when the surgeons import MRI images with virtual reference markers.
"So far we have only used it for our stereotactic radiation treatment applications. It is most useful for metastatic cancers to the brain," Ford said.
This virtual frame placement software is currently the only software available to help surgeons with frame placement prior to SRS and its use allows for safer and more convenient surgery for patients.
"In particular there is no software that allows us to plan a frame placement prior to the day of the patient's procedure. Being able to do this makes the treatment go much faster. In some cases, it also allows us to do the whole treatment in one day rather than having the patient come back for a second day of treatment," Ford said.
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