protection, waste and regulations

Chapter 4 where the reader will find in particular sections dealing with ARSAC for the administration of radioactive substances, the transport of substances, the statutory instruments governing the general use of radiation and specifically its use for medical applications. In particular, the risk assessment of situations involving the administration of radioisotopes on an individual basis can be required frequently due to particular circumstances. The need for adequate staff monitoring and decontamination provision is also essential for the safe provision of radionuclide treatment.

Consideration of the patients’ circumstances in relation to the radionuclide being used is important. Treatments with pure beta emitters, such as yttrium-90, present very little hazard to other people unless the radioactivity is excreted in urine or other body fluids. However, simple hygeine precautions with wound dressings for a short period can also reduce any likely loss of activity and maintain the therapeutic benefit to the patient. By contrast, the administration of ¹³¹I with its half-life of 8 days, gamma ray emission at 364 keV as well as the beta particle emission and avidity for the thyroid gland if ingested in the form of iodide presents a more complex problem. Requirements and guidance are drawn from several sources including the IRMER regulations [26] and the MDGN [10]. Patients receiving more than 30 MBq ¹³¹I must be assessed individually to ensure that they do not pose a hazard to others. In general, patients receiving less than 800 MBq may go home directly after treatment. A journey time of less than one hour is considered reasonable for ambulance and public transport. Advice should be given about seating position in the vehicle to minimize irradiation of fellow passengers. If conveyed by private car, the driver and patient should be advised regarding journey time and seating position in the car. In addition, certain conditions concerning public transport journey times, places of entertainment, use of cutlery and crockery and contact with young children and pregnant women will be required for the following few weeks.

In circumstances when the activity exceeds 800 MBq, the patient will have to be admitted and cared for in specialized accommodation as follows:

• confinement to a single room with impervious wall finishes and flooring and with coved skirtings to ease decontamination

• the room be designated as a controlled area

• exclusive use of a toilet and shower facility connected directly to a main drain

• suitable warning signage to drainage for maintenance workers

• bed linen, towels and clothing must be monitored for contamination before patient discharge

• visiting by adults should be discouraged for the first 24 hours and restricted thereafter

• visiting by children and pregnant women is forbidden

• emergency decontamination kit and radiation monitor readily accessible

• staff must wear at least gowns and gloves to protect their skin and clothing from contamination

• overshoes should be worn if there is any chance of the floor being contaminated

• if possible, utensils such as cutlery and crockery should be disposable and all waste disposal should be dealt with by authorized personnel

• nursing procedures should be carried out in the minimum time compatible with good nursing care

• a clearly documented procedure must be provided to allow artificial resuscitation of a patient but minimize the risk of radioactive contamination.

Patients who have received radioiodine therapy may not be discharged until the radiation dose which they can potentially give to people they come into contact with is significantly reduced. This is achieved by adherence to simple precautions within specified levels of activity. The limit for discharge is generally held to be when the residual level of activity in the body has fallen below 800 MBq. This limit has no legal standing however, so a careful risk assessment is required before discharge, at whatever level.

The 800 MBq limit for iodine-131 was arrived at by carefully modelling likely patient behaviour and compliance. It corresponds to approximately 300 MBq.MeV, so this figure was initially taken as a suitable limit for discharge of patients who had received other therapeutic radionuclides, such as ¹⁵³samarium or ⁹⁰yttrium. Unfortunately, due to differences in half-life and radiation emitted, the extrapolation is not valid [27].

The MDGN [10] contains a table of restrictions which are suitable when discharging patients who have undergone radioiodine therapy for thyrotoxicosis. This includes restrictions on contact with children and any restrictions on the mode of transport used. Self-discharge must be firmly discouraged on the grounds of the hazards to others.

Where risk assessment has shown it necessary, all patients should be given written instructions on leaving hospital about precautions to be taken to minimize the dose to others. This may take the form of a card. Even many weeks after precautions have elapsed, patients may retain enough radioactivity in their bodies to set off radiation alarms at airports. It is wise to question patients on their travel plans prior to discharge and warn them of the possibility of delay.

Following discharge from inpatient accommodation, the room may not be re-used until it has been monitored and declared free from contamination.

In the case of the death of a patient following the administration of a therapeutic dose of radioactivity, due regard must be given to the safety of the relatives, pathologists and undertakers, etc. The MDGN [10] contains a section giving advice on this but a local policy should be written for each treatment offered in that centre.

Staff who prepare, administer or care for patients who have received therapeutic doses should minimize the risk of receiving doses by adherence to good radiation protection principles. They must wear protective clothing when handling the radioisotope, the patient or any articles which may be contaminated. Contaminated goods and clothing must be carefully stored for assay and approved disposal by the medical physics staff. Contamination monitoring should be undertaken by experienced staff and all results recorded. In addition to film or thermoluminescent dosimeters (TLD) badge monitoring, there may be a requirement for periodic monitoring of the staff for inhaled or ingested contamination, e.g. of the thyroid when nursing iodine therapy patients.

Although waste disposal is permitted in gaseous, solid and liquid form and gaseous waste may be encountered from fume cabinets, the majority of waste is liquid and solid. Syringes, swabs, paper tissues and all contaminated material constitute solid waste. Liquid waste arises from radioactive solutions from isotope administration, decontamination procedures and body fluids from patients. The disposal of radioactive waste from a hospital must be organized, carefully controlled and documented in compliance with the UK regulations to avoid hazard to staff patients and the general public. The Environment Agency will have set limits of activity for gaseous, liquid and solid waste for each site in its authorization. The site must show that it disposes of all waste by the best practicable means before authorization is granted.

In most cases, the disposal of radioactive excreta from patients is dealt with by discharging to the sewage system. In this way, the hazard to staff involved in collection and disposal is avoided. This is permitted where there is an adequate inactive effluent flow from the hospital to dilute the waste to a low concentration level, and when the toilets reserved for radioactive waste are connected directly to the main drainage system. Similar conditions must also be applied to the disposal of radioactive liquid waste from the laboratories. The waste pipes between the ward/laboratory and the main sewer should be labelled as potentially radioactive.

Some storage facilities are always required for contaminated belongings or storing high activity waste storage until it can be disposed of. An example would be the tubing and bags from peritoneal dialysis. Such storage facilities must be adequately shielded, designed to prevent risk of escape of material and labelled.

Once the activity has decayed to extremely low levels, it can be disposed of with the rest of the clinical waste. Larger concentrations of activity in solid waste or long-lived radionuclides will require special arrangements for disposal through authorized routes but, once again, strict activity limits are imposed.

Detailed records must be kept of all disposals of radioactive materials irrespective of which route has been used. These records should include the type of radionuclide, its activity at disposal, the route of disposal and the date of disposal.

The limits authorized for disposal as liquid waste under RSA93 [28] may be one of the limiting factors in the ability of a hospital to offer radionuclide therapy. Some countries favour the use of delay tanks to store radioactive excreta before release into the environment, however, the ensuing difficulty in ensuring that the control mechanisms on the tanks are functioning correctly without exposing maintenance workers to unacceptable risk has precluded its widespread use in the UK.

References

[1] Otte A., Mueller-Brand J., Dellas S., Nitzsche E.U., Herrmann R., Maecke H.R. Yttrium-90-labelled somatostatin-analogue for cancer treatment. Lancet. 1998;351:417–418.

[2] de Jong M., Bakker W.H., Krenning E.P., et al. Yttrium-90 and indium-111 labelling, receptor binding and biodistribution of [DOTA0,d-Phe1, Tyr3] octreotide, a promising somatostatin analogue for radionuclide therapy. Eur J Nucl Med. 1997;24:368–371.

[3] Lewington V.J. Targeted radionuclide therapy for neuroendocrine tumours. Endocr Relat Cancer. 2003;10:497–501.

[4] Royal College of Physicians. Radio-iodine in the management of benign thyroid disease. Clinical guidelines: report of a Working Party. Royal College of Physicians; 2007.

[5] Society of Nuclear Medicine. Procedure guidelines for therapy of thyroid disease with iodine-131 (sodium iodide) version 2. Society of Nuclear Medicine; 2005.

[6] Luster M., Clarke S.E., Deitler M., et al. European Association of Nuclear Medicine (EANM).Guidelines for radio-iodine therapy of differentiated thyroid cancer. European Journal of Nuclear Medicine and Molecular Immunology. 2008;35:1941–1959.

[7] Sagel J., Epstein S., Kalk J., Van Mieghem W. Radioactive iodine therapy for thyrotoxicosis at Groote Schur Hospital over a 6 year period. Postgrad Med J. 1972;48:308–313.

[8] Pauwels E.K., Smit J.W., Slats A., Bourquiqnon M., Overbeek F. Health effects of therapeutic use of ¹³¹ I in hyperthyroidism. Q J Nucl Med. 2000;44:333–339.

[9] Robbins R.J., Schlumberger M.J. The evolving role of ¹³¹I for the treatment of differentiated thyroid carcinoma. Journal of Nuclear Medicine. 2005;46:28S–37S.

[10] Medical and Dental Guidance Notes. A good practice guide on all aspects of ionising radiation protection in the clinical environment. Institute of Physics and Engineering in Medicine; 2002.

[11] Seidlin S.M., Marinelli L.D., Oshry E. Radioactive iodine therapy: effect on functioning metastases of adenocarcinoma of the thyroid. J Am Med Assoc. 1946;132:838–847.

[12] Parmentier C. Use and risks of phosphorous-32 in the treatment of polycythaemia vera. J Nucl Med. 2005;46(Suppl.):115S–127S.

[13] Lawrence J.H. Polycythaemia physiology, diagnosis and treatment. Grune and Stratton; 1955.

[14] ICRP Publication 80. Radiation dose to patients from radiopharmaceuticals, Addendum 2 to ICRP 53 and Addendum 1 to ICRP 72. Elsevier; 1999.

[15] ICRP Publication 53. Radiation dose to patients from radiopharmaceuticals. Elsevier; 1988.

[16] Firusian N., Schmidt C.G. Radioactive strontium for treating incurable pain in skeletal neoplasms. Dtsch Med Wochenschr. 1973;98:2347–2351.

[17] Lewington V.J. Cancer therapy using bone-seeking isotopes. Phys Med Biol. 1996;41:2027–2042.

[18] Baczyk M., Czepczynski R., Milecki P., Pisarek M., Oleksa R., Sowinski J. ⁸⁹Sr versus ¹⁵³Sm-EDTMP :comparison of treatment efficacy of painful bone metastases in prostate and breast carcinoma. Nucl Med Commun. 2007;28:245–250.

[19] De klerk J.M., Zonnenberg B.A., Blijham G.H., et al. Treatment of metastatic bone pain using bone seeking radiopharmaceutical Re-186-HEDP. Anticancer Res. 1997;17:1773–1777.

[20] Roberts D.J., Jr. ³²P-Sodium phosphate treatment of metastatic malignant disease. Clin Nucl Med. 1979;4:92–93.

[21] Sisson J.C., Frager M.S., Valk T.W., et al. Scintigraphic localization of pheochromocytoma. N Engl J Med. 1981;305:12–17.

[22] Hattner R., Huberty J.P., Engelstad B.L., et al. Localization of M-iodi (I-131) benzylguanidine in neuroblastoma. Am J Roentgenol. 1984;43:373–374.

[23] Fielding S.L., Flower M.A., Ackery D., Kemshead J.T., Lashford L.S., Lewis I. Dosimetry of iodine-131 metaiodobenzylguanidine for treatment of resistant neuroblastoma: results of a UK study. Eur J Nucl Med. 1991;18:308–316.

[24] Britton K.E., Mather S.J., Granowska M. Radiolabelled monoclonal antibodies in oncology. III. Radioimmunotherapy. Nucl Med Commun. 1991;12:333–347.

[25] Sharkey R.M., Goldenberg D.M. Perspectives on cancer therapy with radiolabeled monoclonal antibodies. J Nucl Med. 2005;46(Suppl. 1):115S–127S.

[26] Department of Health. The Ionising Radiation (Medical Exposure) Regulations 2000. The Stationary Office; 2000. Statutory Instrument 2000 No 1059

[27] Waller M.L. Estimating periods of non-close-contact for relatives of radioactive patients. Br J Radiol. 2001;74:100–102.

[28] Radioactive Substances Act. The Stationary Office; 1993.

Only gold members can continue reading. Log In or Register to continue