Tissue Equivalent Plastic
Cross-section of the telescope assembly, showing the two sections of TEP (grey) sandwiched between three detector pairs, connected via flexible cables (brown) to the analog signal processing board (green).
Tissue equivalent plastic (or TEP) is an A-150 plastic designed specifically to simulate human tissue. Its hydrogen and nitrogen percentages-by-composition are representative of that found in human skin and muscle.
In Nuclear Instruments and Methods in Physics Research, Al-Sulaiti notes that "For energies typically encountered in proton therapy, A-150 plastic appears to be a good representation of water (and thereby very similar to tissue.)"
The atomic-level effects that radiation has on the TEP are useful in deducing what similar effects may occur in humans.
