The principle of radiation protection requires that every radiation load is kept as high and as low as possible. To that effect it is necessary to know the radiation dose, which the patient is given during a nuclear medicine examination. This can be compared with the radiation doses which result from other possible procedures. Furthermore it is desirable to know the health risk that is associated with the radiation load.
Patients, who are awaiting a nuclear medicine examination, are naturally unsettled in respect of the use of radioactive substances. This particularly applies to women in pregnancy, women who maybe pregnant or breastfeeding. Even when the doctor, after weighing up all the options, considers the examination to be necessary, it is vital that the risks of such an examination are presented to the patient in a comprehensible way.
For example such a risk could be presented here compared to smoking a few cigarettes or clocking up a certain distance by car or by plane. The radiation load is measured as an "effective dose" and given in millisievert [mSv]. For the vast majority of diagnostic examinations the dose is below 5 mSv, very often even below 1 mSv.
Information on the radiation load of individual examinations should only be perceived as guidelines: The individual dose depends on different factors such as administered activity, the anatomy of the individual patient and the respective organ function.
The natural radiation load in Austria is around 2-3 mSv per year. That is an average which is subject to fluctuate depending on the place of residence of a certain person. The risk of causing a lethal cancer illness in a person with a dose of 1 mSv is statistically 50 to 1 million (0.005%).
If this person is still able to reproduce then a quarter of this value applies to all future generations. To put this risk into proportion, let it be said that the risk of death due to anaesthesia during an operation is 40 to 1 million (0.004%).
The risk of drivers meeting death in an accident with an annual mileage of around 15 000km is 200 to 1 million (0.02%).
Smoking only one cigarette a day over a ten year period kills 2 500 out of 1 million smokers (0.25%). And lastly, already from the age of 55 the risk of dying from whichever cause is 10 000 per 1 million of the population (1%). Table 1 shows these risks in relation to a radiation load of 1 mSv.
Risk in comparison to a radiation dose of 1 mSv
|1 mSv ||travelling 200 km by motorbike |
|1 mSv ||travelling 3750 km by car |
|1 mSv ||flying 18000 km |
|1 mSv ||smoking 75 cigarettes |
|1 mSv ||clinbing for 75 min |
|1 mSv ||working 1-2 years in a factory |
|1 mSv ||living 17 hours as a 60 year old |
Recently under the perspective of individual loss of life expectancy a clear risk estimate by means of calculating the risk of illness, accidents, socio-economic factors and more is being trialled. This type of estimated risk volume is slightly more comprehensible compared to the previous information.
The one-off exposure to 1 mSv would result in a theoretical loss in life expectancy of 0.3 days, such a loss for 10 mSv is 1.5 - 3 days. This is far less than the loss of life expectancy e.g. due to illness, but also due to self-inflicted measures such as alcoholism, smoking or obesity. Being half a kilogram overweight is associated with a theoretical loss of life expectancy of one month. These observations reveal that a radiation load, which is in the standard range of most nuclear medicine examinations (1 -5 mSv), which is associated with a theoretical risk, is however insignificantly low. Additionally in patient examinations with nuclear medicine methods no adverse consequences have been reported up until now, even taking into account child examinations.