Some ratioisotopes are used for medical imaging . A radioisotope is injected into th blood of a person. Malignant tissue absorb and retian this isotope much more efficiently than other healthy tissues. A sample of radio isotope having half life of 5 hour and activity of 22mCi is injected into the blood aof a patient. the isotope enters into thyroid glnads through the blood streams. The isotope radiates gamma photons each having energy of `2xx10^(-8)muJ`. (a) Qualitatively sketch the amount of radio isotope in the thyroid glands as a function of time. (b) Sometime after the injection a scan of the glands is taken over a period of 20 minute. The total energy emitted by the glands was found to be `6xx10^(-4)J`. Assume that the thyroid glands are quickly saturated (with isotopes) after the injection and almost 50% of the injected isotopes are absorbed by the glands. Make an estimate of the time after the injection when the scan was performed.