Useful information

The patient receives information about the examination procedure from the nuclear medicine staff. Patients might feel stressed and fearful about the procedure, often due to inaccurate information from non-experts. Therefore, it is essential that patients are provided with accurate and clear information about the basic principles of the procedure when considering a nuclear medicine examination.

Once a patient is scheduled for a nuclear medicine examination, they will receive information sheets detailing the procedure. Additionally, the medical team and nursing staff should provide explanation and clarification of the examination procedure. In some cases, it may be helpful to ask the nuclear medicine staff to speak directly with the patient.

Most examinations require little or no preparation from the patient. However, for some procedures, it is important that the patient has had enough to drink.

Such examinations should not be conducted on a day when oral intake is not allowed for the patient (e.g., due to other planned examinations).

For PET examinations using [18F]FDG, it is generally necessary that the tracer is administered while the patient is fasting with a normal blood sugar level. Therefore, patients must fast for at least 5 hours and can only have sugar-free drinks or infusions for hydration.

Iodine, used as a contrast agent in conventional radiological examinations, can block the uptake of the radionuclide in thyroid examinations. If possible, a thyroid scintigraphy should be performed before any examination involving contrast agents. Failure to observe this may result in having to postpone a thyroid scintigraphy for up to eight weeks after the administration of a contrast agent.

The principle of radiation protection requires that every exposure to radiation be kept as high as necessary and as low as possible. Consequently, it is necessary to know the radiation dose resulting from a nuclear medicine examination for the patient. This dose can be compared with those from other possible procedures. Additionally, it is desirable to understand the health risks associated with the radiation exposure.

Patients who are scheduled for a nuclear medicine examination are naturally concerned about the use of radioactive substances within their bodies. This is especially true for pregnant women, those who might be pregnant, and breastfeeding mothers. Even if the doctor deems the examination necessary after considering all options, it is essential to present the risks of such an examination to the patient in a way that they can understand.

For example, the risk can be compared to smoking a few cigarettes or traveling a certain distance by car or plane. The radiation exposure is measured as "effective dose" and given in millisieverts (mSv). For the majority of diagnostic examinations, the dose is under 5 mSv, and often under 1 mSv.

The information about the radiation dose of individual examinations should be understood as approximate values: The individual dose depends on various factors, such as the administered activity, the patient’s anatomy, and the specific organ function.

For comparison: The natural radiation exposure in Austria is about 2–3 mSv per year. This is an average value that varies depending on a person's location. The statistical risk of causing a fatal cancer with a dose of 1 mSv is 50 in 1 million (0.005%).

For individuals still capable of reproduction, this risk is a quarter of that value for subsequent generations. To put this risk into perspective, the risk of death due to anesthesia during surgery is 40 in 1 million (0.004%).

The risk of a fatal traffic accident is 200 in 1 million (0.02%) for a yearly mileage of about 15,000 km. Smoking just one cigarette a day over a period of 10 years results in 2,500 deaths per 1 million smokers (0.25%). And, from the age of 55, the risk of dying from any cause is 10,000 per 1 million people (1%). Table 1 shows these risks in relation to a radiation dose of 1 mSv.

Risks Compared to a Radiation Dose of 1 mSv:

• 1 mSv = 200 km of motorcycle riding
• 1 mSv = 3,750 km of driving a car
• 1 mSv = 18,000 km of flying
• 1 mSv = 75 cigarettes of smoking
• 1 mSv = 75 minutes of climbing
• 1 mSv = 1–2 years of working in a factory
• 1 mSv = 17 hours of living as a 60-year-old

Recently, a more understandable risk assessment has been attempted by calculating the loss of life expectancy due to diseases, accidents, socioeconomic factors, and other factors. This type of risk estimation is easier to understand compared to the previous figures.

A single exposure of 1 mSv would theoretically result in a loss of life expectancy of 0.3 days, while an exposure of 10 mSv would result in a loss of 1.5–3 days. This is much lower than the loss of life expectancy due to diseases or self-inflicted measures such as alcoholism, smoking, or obesity. For example, half a kilogram of excess weight is associated with a theoretical loss of life expectancy of one month. These observations highlight that radiation exposure in the typical range of most nuclear medicine examinations (1–5 mSv) poses a theoretical risk that is negligibly small. Furthermore, no adverse effects have been reported from patient examinations using nuclear medicine methods, even considering studies involving children.

The internationally accepted maximum allowable radiation exposure for occupationally exposed individuals (such as those working in a radiology department or a nuclear medicine department, e.g., radiologic technologists) is 50 mSv per year, or a total dose of 100 mSv over a period of 5 years. For the general public, the annual limit according to ICRP (International Commission on Radiation Protection) guidelines is 1 mSv, though up to 5 mSv may be permitted in specific cases, such as for the care of patients.

There is sufficient research and measurement data showing that healthcare staff (considered as "general public" in this context) involved in the care of patients undergoing nuclear medicine examinations are not exposed to significant radiation. Even with prolonged direct contact with patients, the radiation exposure for healthcare staff is minimal (e.g., after a bone scan, it is 2–5% of the annual dose limit for non-occupationally exposed individuals). Often, it is much lower, around 0.05–0.5% of the natural annual radiation exposure. Thus, it is negligibly low.

For diagnostic examinations, the risk to staff, as mentioned, is low. Even a small distance between the staff and the patient significantly reduces the radiation dose. This fact is important for accompanying persons who bring patients to nuclear medicine examinations. Although the risk to the fetus of pregnant accompanying persons is unlikely, it seems prudent to avoid unnecessary radiation exposure to the pregnant person and their fetus. Therefore, pregnant individuals should avoid accompanying patients. Additionally, pregnant staff members should be kept from direct patient care for the first 12 hours after the administration of a radiopharmaceutical for diagnostic purposes.

There is no need to isolate patients from each other, as the distances between them are already sufficient to prevent significant radiation exposure to neighboring patients. For patients who have undergone radionuclide therapy, it is important to review the information sheet provided to them.

If necessary, some nuclear medicine examinations can be performed on pregnant women, such as a lung scan to diagnose or rule out a pulmonary embolism. Pregnancy is not an absolute contraindication for a nuclear medicine examination. However, the well-being of the developing child must always be considered. Therefore, the risks and benefits must be weighed as carefully as possible, and the woman must be thoroughly informed.

Routine examinations are not conducted on pregnant women unless the results are urgently needed for current treatment and cannot be postponed until after the pregnancy. The dose to which a fetus is exposed varies greatly depending on the type of examination and can be minimized for pregnant women by reducing the administered activity.

The principal risk for the fetus is considered to be the potential development of cancer in childhood. Estimates of this risk range from 30 to 130 cases per 1 mSv. There is no evidence of congenital malformations in a fetus exposed to less than 100 mSv. The possibility of developmental delay is currently considered to be a reduction in IQ by 0.03 points per mSv if the exposure occurs during the gestational period of 8 to 15 weeks.

In simple terms, no detectable effects have been observed from any nuclear medicine examination. No harm is seen to the live-born child from exposure of an embryo during the first three weeks after conception.

The consideration of a nuclear medicine examination for a pregnant woman should be discussed with the head of the relevant department or a responsible physician in consultation with a nuclear medicine specialist. It is crucial that a pregnant or breastfeeding woman receives an explanation of the risks associated with such an examination before coming in for the procedure.

Pregnancy and the postpartum period are emotionally demanding, and radiation exposure during pregnancy often raises significant concerns. A patient in this situation may seek advice from her partner, and there may not be time for this if she is only informed of the potential risks shortly before the examination.

Some radiopharmaceuticals accumulate in breast milk. If a radionuclide examination is necessary during lactation, a short interruption of breastfeeding is recommended. The duration of the interruption depends on the radiopharmaceutical used. If possible, the baby should be breastfed immediately before the nuclear medicine examination.

The mother should be encouraged to pump her milk during the interruption, which is beneficial for her own well-being by preventing milk stasis and for maintaining a continuous milk production. The pumped milk must be discarded. If a nuclear medicine examination is desired for a breastfeeding mother, the nuclear medicine department should be contacted in advance.

Adverse reactions to radiopharmaceuticals are very rare, occurring in about 1 in 100,000 cases. This risk is approximately 1,000 times lower than that associated with X-ray contrast agents.

As with any intravenous injection, there is a risk of anaphylaxis with radiopharmaceuticals, but this risk is extremely small, and most reactions are mild. No deaths due to radiopharmaceuticals have been reported worldwide in recent years. Clinical manifestations of side effects are categorized into anaphylactoid immediate reactions (nausea, vomiting, hypotension, incontinence, syncope, skin flushing with tachycardia), allergic delayed reactions (rash, urticaria, itching, shortness of breath, chest pain, palpitations, and tachycardia), pyrogenic reactions (fever, headache), various reactions (metallic taste, cyanosis, chills), and vasovagal reactions, although the latter cannot be definitively attributed to the radiopharmaceutical. Typically, these side effects are mild and usually do not require special treatment. Side effects from radiopharmaceuticals are rare, occurring in about 0.001–0.006% of cases.

In a comprehensive study from the USA, the prevalence of radiopharmaceutical-related side effects was found to be 0.0023%. This study included 783,525 examinations conducted in 18 institutions over a period of 5 years. In total, only 18 side effects were reported, none of which resulted in permanent damage or adverse outcomes for the affected individuals.

For most diagnostic nuclear medicine examinations, no special care measures are necessary, other than those dictated by the clinical condition of the patient. This does not apply to therapy with radionuclides or radiopharmaceuticals, for which specific measures must be taken. All necessary measures for handling patients undergoing radionuclide therapy should be discussed in advance. All patients receiving a therapeutic dose of a radiopharmaceutical will be informed in a timely manner by our staff on what to expect and how to manage their care (information brochure).

In addition to the examination request, any available images and the patient's medical history, including current medication intake, should be provided.

If medication intake is necessary during the stay in our department, clear information about the medication and its dosage must be provided. Patients arriving by medical transport from other hospitals or nursing homes must expect a certain waiting period before their return transport.

The nursing staff should inform our employees about any special needs of the patients, e.g., in cases of diabetes or bedsores. Although every effort is made to conduct the examination as efficiently as possible, the patient may be absent from their ward for an extended period. Visitors can accompany the patient.