Unit: Medical Imaging Task 3 Case Studies (AC 5.1, 5.2) 5.1 Compare and contrast the uses and relative advantages of X-rays, ultrasound, gamma camera and MRI in examining internal structures. 5.2 Evaluate the hazards of X-rays, ultrasound, gamma camera and magnetic resonance in medical imaging and explain the control methods used to minimize risk to patients and operating staff. You are provided with information describing safety procedures used in 3 medical imaging departments. For each department a) explain the nature of the hazards to patients and staff b) explain how the procedures reduce the hazardous effect Explain the circumstances where each method of imaging might be used in preference to ultrasound, which has relatively low levels of hazard. Scenario 1: Nuclear Medicine Imaging Patients who have had radioactive substances administered to them may be treated as outpatients when radiation exposures caused to family members and other persons by the residual activity in these patients remain insignificant. The following dose constraints shall be applied: Family members of the patient Children (including unborn children) 1 mSv/treatment Adults (under 60 years of age) 3 mSv/treatment Adults (60 years of age and older) 15 mSv/treatment Other persons (members of the public)*) 0.3 mSv/year If it is possible that the dose constraints of family members or any other individuals might be exceeded, (e.g. because of a long journey, or if there are small children at home) the patient must remain in hospital until the residual activity in this patient has fallen sufficiently. Patients who have received radionuclide therapy shall be accommodated in the hospital facilities in a manner that minimizes the radiation exposure of workers, other patients and visitors. After 13I treatment the patient may be released from hospital after receiving the relevant radiation protection instructions when the residual 131 activity in patient no longer exceeds 800 MBq. Patients should be able to use public transportation for journeys of no longer than two hours. Patients with incontinence should not be released to their own home or to nursing home immediately after treatment. . When using beta-emitting radionuclides, such as 32P, 89Sr and 0Y, no radiation protection measures are necessary after the residual activity in a patient no longer exceeds 200 MB