Final answer:
99mTc-HMPAO is a radiopharmaceutical that emits gamma rays upon decay. These gamma rays are used for medical imaging of various organs, and the compound is preferred for its short half-life and diagnostic efficiency.
Step-by-step explanation:
99mTc-HMPAO is a radiopharmaceutical used extensively in medical imaging. This compound utilizes a metastable form of technetium, denoted by 'm' in 99mTc. The 'm' stands for metastable, indicating that the nucleus of the technetium atom is in an excited state. The decay of this metastable state produces a single gamma ray (symbolized as 'y ray' in the information) with an energy of 0.142 MeV.
The question asks which type of particle 99mTc-HMPAO emits. Based on the provided information, which cites the detection of y-rays, we can deduce that 99mTc-HMPAO emits gamma rays. This is consistent with the decay process of the metastable technetium-99m, which is known for its diagnostic use in medical imaging due to the emission of a 0.142-MeV gamma ray.
In summary, when 99mTc decays, it does not emit alpha particles, beta particles, or X-rays but instead emits gamma rays, which are used to image various organs such as the skeleton, heart, lungs, and kidneys. Moreover, the radiation dose to the patient is limited due to the short half-life of 99mTc, which is 6.0 hours. The use of 99mTc-HMPAO and similar compounds in nuclear medicine is vital for non-invasive diagnostics and provides valuable information on the function of specific organs and tissues.