What thickness of crystals is better for imaging radiopharmaceuticals with higher energies; with decreased resolution?

• A. Thinner
• B. Thicker
• C. Same
• D. Variable thickness

Answer: (B)

Thicker crystals are preferred when imaging higher-energy radiopharmaceuticals because stopping power—and thus detection efficiency—increases with crystal thickness. Higher-energy photons are more penetrating, so a thicker crystal captures more of them, producing more detectable light and improving overall counts. The trade-off is that greater thickness leads to more light spread and depth-of-interaction uncertainty, which degrades spatial resolution. When the imaging task prioritizes detecting higher-energy photons and accepts some loss of resolution, using a thicker crystal improves sensitivity and practical image quality.