"Sodium iodide (NaI) is the most common crystal used in gamma cameras. It is favoured due to high atomic number of 53, and is able to absorb 90% of photons from Technetium-99m. However, it is only able to absorb 30% of photons from iodine-131 2."
Line 5:164·Put a space between the number and the unit in 'Technetium-99m'.