General Public
- What are the radiation risks to the public?
- The patient has to use public transport regularly. What precautions should he take?
- Will the radioactivity from the patient harm the environment?
- The patient is undergoing regular haemodialysis. Is this a risk?
- How is the radioactive waste from the patient disposed of, and does it pose a risk?
1. What are the radiation risks to the public?
The public can be exposed to radiation from a radionuclide therapy patient as :
- external radiation emitted from the patient, when in close contact (such as on public transport),
- internal contamination from radioactive body fluids,
- exposure through environmental pathways including sewage, discharges to waterways, or cremation of bodies.
In the case of the public, the normal dose constraint of 1 mSv/year applies.
Any exposure of the public are predominantly caused by external exposure. The various specific discharge guidelines give information, where appropriate, on this matter.
The other causes are very much less likely, and would result in very low exposure only.
2. The patient has to use public transport regularly. What precautions should he take?
If travel times sitting next to one person are less than a few hours, radionuclide therapy patients rarely present a hazard, and then only for iodine-131 therapy.
For example, take the case of a patient treated with 600 MBq of iodine-131 for hyperthyroidism. One hour of travel daily on public transport in the first week after therapy, and nine hours per day in the second week, next to the same person, will result in an effective dose of <1 mSv-1.
For family members, the suggested travel time using public transport with hyperthyroid treatment patients is seven hours per day for the first week and 24 hours per day for the second week, to restrict the effective dose to 5 mSv/yr - in other words, no travel restrictions are necessary.
3. Will the radioactivity from the patient harm the environment?
The main radionuclide discharged into the environment following radionuclide therapy is radioiodine (iodine-131). Due to the half-life of 8 days, iodine-131 may be detected in small amounts in the general environment after medical use. However, the high degree of dilution and dispersion by mixing with normal waste discharges, and the length of time required for any contamination to be returned to the ecosystem, has meant that an environmental impact has not been measurable.
Some countries require short-term storage of hospital waste (usually urine only) containing radionuclides from hospitalized therapy patients until the activity has reached a particular level; however, the ICRP does not specifically require this.
For radionuclides used in bone pain palliation, it is suggested in this guideline that where the therapy is given to an outpatient, the patient should empty the bladder at least once before leaving the hospital.
If the social system and infrastructure in a country mean that there may be contamination risks from discharged patients, it may be necessary to hospitalize the patient (if an outpatient therapy), or extend the normal hospitalization time.
4. The patient is undergoing regular haemodialysis. Is this a risk?
In such cases, no significant contamination of the dialysis machines has been reported. There may be slight contamination of disposable items such as lines and waste bags, which may require storage for a few half lives in the case of iodine-131. In most cases, however, no precautions will be required.
5. How is the radioactive waste from the patient disposed of, and does it pose a risk?
The predominant issue is radioactive excreta - urine and faeces. The specific therapy discharge guidelines will recommend that excreted radioactivity levels be low enough such that the public dose limits would not be exceeded. In addition, the ICRP does not recommend that urine from therapy patients be stored - a procedure which has minimal benefit, and can even lead to higher exposures due to multiple handling of the urine.
Other wastes such as dressings will usually end up in landfill or incinerators. Again, the specific therapy discharge guidelines recommend that any contamination be of an extremely low and negligible level.
Solid waste from the patient's stay in hospital is a different matter, and is normally incinerated at high temperature along with other biological waste (which does not pose a contamination problem), or held for a period until radioactive decay brings the activity to an acceptable level. The relatively short half lives of therapeutic radionuclides make this a manageable problem.
- Information for
- Health Professionals
- Member States
- Patients