Q: What is Nuclear Medicine?

A: Nuclear Medicine is the medical specialty that uses very small amounts of radioactive material to diagnose and treat disease. These materials, or tracers, are substances that are attracted to specific organs or tissues by the nature of their chemical makeup. The tracer emit energy, in the form of radiation, that is detectable by highly specialized equipment known as gamma cameras or scintillation cameras. The information (in the form of energy) is collected by the camera system and is transformed into images, which provide anatomical and functional detail of the body part being imaged.

Q: What are the radiation hazards associated with the Nuclear Medicine patient?

A: Nuclear Medicine procedures are very safe. A patient only receives an extremely small amount of tracer, just enough to provide sufficient diagnostic information. The patient dose, in many cases, is equal to or less than common X-ray procedures. Most tracers pass quickly from the body through normal bodily functions. Patients should be encouraged to drink additional fluids as this will aid in eliminating the tracer more quickly.

Q: Are there special precautions for pregnant staff when handling patients who have had a Nuclear Medicine procedure?

A: For most diagnostic procedures there would be no need for pregnant staff to take any additional precautions other than limiting their direct contact to as short as necessary. Radiation exposure follows the inverse square law which makes it dependant on both time and distance from the source. The inverse square law states that if you double your distance from the source your exposure rate drops by a factor of four, or if you triple your distance, your exposure drops by a factor of nine. This, combined with the fact that most diagnostic procedures use very small doses, means that the risk to hospital staff is very small. Any patients receiving a therapeutic Nuclear Medicine procedure should be handled by you after consultation with the Radiation Safety Officer and in accordance with the policies of the respective institutions.

Q: Are Nuclear Medicine procedures performed on children?

A: Yes, Nuclear Medicine procedures are commonly performed on children and are generally used to evaluate bone pain, injuries, kidney or bladder conditions or infections. The dose for the patient is adjusted according to the child's age and weight. Sedation is sometimes required depending on the test being performed and the child.

Q: Why are there delays between Nuclear Medicine procedures and not between X-ray or Ultrasound procedures?

A: Nuclear Medicine procedures often use the same radioactive tracer combined with different chemical elements to visualize different organ or tissue systems. As these products break down and are eliminated from the body they would interfere with the imaging of another organ system as they would no longer be found only in the target organ or tissue. The Nuclear Medicine camera systems would not be able to differentiate the target organ or system from that of a previous test. For the most common tracer of Technetium it generally takes up to 48 hours to clear the body before another test can be ordered. Isotopes such as Gallium and Iodine can take considerably longer.

Q: What amount of radiation exposure is safe to receive?

A: There is no dose below which radiation induced injury is absent. Every X-ray exposure involves risk. The benefits of radiation exposure should outweigh the risks, therefore, occupational exposure should be at its absolute minimum.

Q: What kind of protective devices are available to me if I must be near an area where X-ray exposures are taken?

A: A lead apron is worn that covers 80% of your bone marrow. A thyroid shield is often used to protect the thyroid gland. Lead gloves protect your hands if you are supporting or assisting a patient who is having an X-ray and your hands are in close proximity to the X-ray beam. However, radiation effects to the skin and extremities are non-existent at today's dose levels.

Q: How many portable chest X-rays can be taken in our area in one month?

A: The intensity of radiation one (1) metre from the portable is so small that a radiation worker would have to be exposed to 2000 films a month to reach the dosage allowed the general public.

Q: Where is the best place to stand during an X-ray if you are assisting?

A: If you are holding or supporting a patient always stand off to the side so that the X-ray beam is not pointing at you. No one should routinely hold or assist a patient during an X-ray exam.

Q: Why are the patient's gonads protected during a chest or foot X-ray?

A: This is a radiation safety precaution to protect the patient from scattered radiation. The impact of radiation exposure on future generations has always been a concern. Radiation can produce mutations through unrepaired structural breaks in chromosomes or through changes in the order based on the DNA chain. If this occurs in germ cells it can be transmitted to future generations. Female patients between the ages of 11 - 55 years are questioned as to the possibility of pregnancy before irradiation. All patients are given gonadal shielding routinely up until the age of 55 years.

Q: What are the primary risks to the general public from medical radiation?

A: The primary risks are called stochastic effects. These effects include carcinogenic and genetic effects. Ordering physicians consider the risks associated with an X-ray procedure vs the benefits of a speedy diagnosis and treatment for the patient.

Q: How can I help to minimize medical X-ray exposure to my patients?

A: The largest source of unnecessary patient dose is unnecessary X-ray examinations. You can minimize exposure through communication. For example: questioning the orders for routine examinations. These should never be performed when there is no precise medical indication. Routine chest X-rays for hospital admission or annual physicals or asymptomatic patients are not necessary. Check to see if the patient has had X-rays done through the emergency department before being admitted to your floor. Ask the patient if recent films of the area of interest were performed at another site or clinic or under another physician.

Q: What factors should I consider to reduce my occupational exposure?

A: Occupational exposure can be reduced by the effective use of time, distance and appropriate shielding. Take the following steps:

- reduce the amount of time spent in the area of the radiation source
- remain as far from the source as possible. The inverse square law states that if you double your distance from the source your exposure rate drops by a factor of four, or if you triple your distance your exposure drops by a factor of nine.
- utilize the use of fixed barriers or mobile shields as well as lead aprons and thyroid collars.