School of Infection & Immunity

Procedure Notes for use of radioisotopes and radioiodine

Registering to use radioisotopes

All users of radioisotopes should have completed a registration form as a user, completed the training course run by Radiation Protection Services, and received a dosemeter badge from the local Radiation Protection Officer, Jim Scott, or the person delegated by them for this task.

Note: Female workers who become pregnant must inform the University Radiation Protection Office. The information will be treated in the strictest confidence and will not be divulged without prior written consent. All efforts should be made to ensure that the dose to the foetus is <1mSv for the duration of the pregnancy. For women who are breast-feeding, extra precautions should be taken in the workplace to ensure that radiation levels are minimal.

Use of Unsealed Radioactive Material

• Risk assessments should be carried out for each new process and updated regularly.
• The delivery of the radioisotope to the end-user should always include a primary stock disposal sheet marked with its GBRC source code. The local radiation protection supervisor, Jim Scott, will also fill in a record card for each isotope and this card will be retained by him. See also ordering radioisotopes. 
• The experimenter must know the physical and chemical properties of the radiochemical in use and should guard against the unnecessary production of radioactive gases and aerosols.
• Millicurie (40 MBq) activities of stock radioisotope solution should be dispensed in a fume cupboard in a radioisotope dispensary. Smaller activities of the least radiotoxic materials may be handled in a Supervised Radiation Area provided an area of bench is segrgated for radioisope work, covered with "Benchkote" (R) absorbent side up, and marked with a short length of "radiation hazard" warning tape. See also Classification of Radiation Areas.
• All the manipulations must be carried out over a spill tray lined with absorbent tissue. Where there is any possibility of radioactive gas or aerosol being produced, the experimental system must be completely enclosed, and the whole operated in a Class 3 fume cupboard.
• A laboratory coat (buttoned up) and plastic disposable gloves should be worn, and a radiation dosemeter (if appropriate) should be worn at chest level. Other personal protective equipment such as lead-lined gauntlets or apron should be considered as part of the prior risk assessment..
• Monitor the apparatus used as the experiment proceeds, and monitor the hands frequently.
• Place all radioactive waste materials in the special receptacles provided.
• If the work is to be carried out in the researcher's laboratory, and not in the radioisotope laboratory (ie, the amounts to be used are below the handling limit - see handling and Storage limits) :-
  • ensure that the laboratory where the work is to be carried out is registered with the Radiation Protection Service (RPS) for radiation work, and that all sinks where radioisope disposal will occur is also registered with the RPS. Prepare a separate waste bin, with radiation disposal bags, for the solid waste. If solid waste disposal bags contain high-energy emitters, ensure that they are well-shielded.
  • prepare a bench area with benchkote and radioactive marker tape for the work area. If screens are to be used, ensure that all staff in the laboratory, and not just the person handling the isotope, will be protected.
• After the experiment, monitor and decontaminate all the apparatus used. Monitor all laboratory surfaces including the front of the bench and floor, and ensure that they are not contaminated.
• Finally check for personal contamination, remove personal protective equipment, wash hands and monitor them before leaving the laboratory.

Maintaining Laboratory Records

It is a legal obligation for the user of the radioisotope to be able to demonstrate the location of the full amount of the radioisotope at all times. This requires records with a level of detail in excess of that covered by the card issued by stores. At any time, the amount of radioisotope remaining in the stock bottle, plus the amount recorded as present in any diluted solutions/aliquots/scintillation vials, plus the amount recorded as disposed in liquid or solid waste, must total the amount delivered

Maintain detailed records for the isotope as follows:-

1. Post disposal record sheets by the solid waste bin and by the sinks designated for liquid waste. On every occasion of radioactive waste disposal, record the type of isotope, the amount disposed, the source code, the user, and the date.
2. Label all diluted solutions/aliquots containing isotope with the source code and the date.
3. Maintain a detailed record sheet for each source code, and on each occasion where radioactivity from that source code is used, record the amount of isotope used; where it moves to (ie, to a diluted solution in the fridge/freezer, to solid waste, or to liquid waste); the user; the date; and the amount of isotope remaining in the stock bottle.
4. Once the batch of isotope is all used, summarise the usage in the table on the second of the two cards issued with it, and return the completed card to your local collection point.
5. On the first few days of each month, complete a summary of the liquid radioactive waste disposal that month, and return it to your local collection point.
6. The detailed records should be kept for 5 years.

Note that all recordings should be done in Mega-bequerels (MBq).
1 micro-curie(uCi) = 0.037 Mega-Bequerels(MBq).

Ordering of Radioisotopes

• All internal order requisition forms for radioisotopes should be clearly marked as ‘yes’ for radiation.
• All radiochemical orders must be countersigned by Jim Scott, Jim Reilly or Helen Arthur prior to the order being placed.
• All radiochemicals arriving in the building will be received by Jim Scott, who will allocate a vial number before putting the vial in the appropriate stock storage location, or before handing it over to the person by whom it was ordered. Isotope vials for personal use are generally stored in the appropriate fridge or freezer in the Dispensary. End-users will be notified of delivery.

Storage

Label all fridges/freezers to be used for the storage of radioisopes.

Store all radioactive material not in use in the safe or refrigerator designated for that purpose. Ensure that material is properly labelled and that secondary containment is provided.

Storage of radioisotopes in unlocked fridges and freezers in corridors, or in areas where there is general access is not permitted since only authorised personnel should have access to radioactive material.

Dosemeters

All radiation workers on registering with RPS are issued with a dosemeter. This should be worn at chest level for best effect. The dosemeters are changed every 2 months.

Thermoluminescent finger doesemeters are available for use where millicurie (40 MBq) activity of phosphorus-32 or other isotopes emitting penetrating radiation are being dispensed.

Use of Radioiodine

Chemical compounds containing radioiodine are particularly hazardous since there is a possibility of a release of free iodine which will volatilise and lead to an airborne contamination hazard.
Moreover, an intake of radioiodine will concentrate in the thyroid gland, irradiating the gland at a high level. An information sheet giving details of the precautions which should be observed in the use of radioiodine is available from the Radiation Protection Service.

Non-Ionising Radiation

When using bactericidal UV lamps enclosed within fume hoods, hands and arms must be fully protected. Thee is no significant risk of burning with the use of non-bactericidal long-wave UV lamps.