Honors Thesis Archive
| Author | Steven La Count |
|---|---|
| Title | 60Co/137Cs γ–ray imaging of a geode, phantom and a human forearm model |
| Department | Physics |
| Advisor | Dr. Paul Voytas, Dr. Elizabeth George, Dr. David Finster |
| Year | 2015 |
| Honors | Departmental Honors |
| Full Text | View Thesis (794 KB) |
| Abstract | This experiment explored a common non-invasive way to map the internal composition of objects, called Computed Tomography (CT), for future pedagogical purposes. 60Co has a characteristic spectrum with peaks where it emits γ–rays at 1.17 and 1.33 MeV and 137Cs has one γ-ray peak at 0.662 MeV. These high-energy γ–rays can easily pass through most objects. Their unattenuated intensities were known from the activity of their respective source(s) as well as their distance from a detector. By comparing unattenuated intensity with the attenuated intensities at different x-y slice positions, the internal density information of an object can be found using an iterative algorithm. From this, a contour plot showing the structural density of an object was constructed. A geode was the first object examined; unfortunately, its attenuation values did not converge and satisfy both horizontal and vertical attenuations at the same time, so meaningful contour plots were not able to be obtained. Thus, a phantom consisting of polyethylene beads and a brass slab in a cardboard cube (of known composition) was imaged. Its contour plot again did not have converging values, but both of the linear attenuation values in the grid (to satisfy the horizontal and vertical information lines separately) produced contour plots that were very close to being quantitatively the same and that were similar to expected results, with a slight offset. A human forearm model was built from a beef bone and gelatin and imaged in much the same way, again with the image being suggestive of the bone’s structure but with an offset. |
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