European Journal of Nuclear Medicine

, Volume 23, Issue 2, pp 123–130 | Cite as

Radiation dose rates from patients receiving iodine-131 therapy for carcinoma of the thyroid

  • S. F. Barrington
  • A. G. Kettle
  • M. J. O'Doherty
  • C. P. Wells
  • E. J. R. Somer
  • A. J. Coakley
Original article

Abstract

Patients treated with radioiodine present a radiation hazard and precautions are necessary to limit the radiation dose to family members, nursing staff and members of the public. The precautions advised are usually based on instantaneous dose rates or iodine retention and do not take into account the time spent in close proximity with a patient. We have combined whole-body dose rate measurements taken from 86 thyroid cancer patients after radioiodine administration with published data on nursing and social contact times to calculate the cumulative dose that may be received by an individual in contact with a patient. These dose estimates have been used to calculate restrictions to patients' behaviour to limit received doses to less than 1 mSv. We have also measured urinary iodide excretion in 19 patients to estimate the potential risk from the discharge of radioiodide into the domestic drainage system. The dose rate decay was biexponential for patients receiving radioiodine to ablate the thyroid after surgery (the ablation group, A) and monoexponential for these receiving subsequent treatments for residual or recurrent disease (the follow-up group, FU). The faster clearance in the follow-up patients generally resulted in less stringent restrictions than those advised for ablation patients. For typical activities of 1850 MBq for the ablation patients and 3700 MBq or 7400 MBq for the follow-up patients, the following restrictions were advised. Patients could travel in a private car for up to 8 h on the day of treatment (for an administered activity of 1850 MBq in group A) or 4 and 2 h (for activities of 3700 or 7400 MBq in group FU) respectively. Patients should remain off work for 3 days (1850 MBq/group A) or 2 days (up to 7400 MBq/group FU). Partners should avoid close contact and sleep apart for 16 days (1850 MBq/group A) or 4–5 days (3700 or 7400 MBq/group FU). Contact with children should be restricted according to their age, ranging from 16 days (1850 MBq/group A) or 4–5 days (3700 or 7400 MBq in group FU) for younger children, down to 10 days (1850 MBq/group A) or 4 days (up to 7400 MBq/group FU) for older children. The cumulative dose to nursing staff for the week after treatment was dependent on patient mobility and was estimated at 0.08 mSv for a self-caring patient to 6.3 mSv for a totally helpless patient (1840 MBq/group A). Corresponding doses to nurses looking after patients in group FU were 0.18–12.3 mSv (3700 MBq) or 0.36–24.6 mSv (7400 MBq). Sensible guidelines can be derived to limit the dose received by members of the public and staff who may come into contact with cancer patient treated with radioiodine to less than 1 mSv. The rapid clearance of radioiodine in patients treated on one or more than one occasion means that therapy could be administered at home to selected patients with suitable domestic circumstances. In most cases the restriction times, despite the high administered activities, are less than those for patients treated for thyrotoxicosis. The concentration of radioiodide in domestic drainage systems should not pose a significant risk.

Key words

Thyroid carcinoma Iodine radioisotopes Radiometry 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    National Radiological Protection Board.Guidance notes for the protection of persons against ionising radiation arising from medical and dental use. London: HMSO; 1985: 57.Google Scholar
  2. 2.
    Title 10, Chapter 1,Cose of Federal Regulations — Energy, Part 35, Section 35.75, 31 October 1986.Google Scholar
  3. 3.
    Allen HC Jr, Zelenski JP. 430 non-hospitalised thyroid cancer patients treated with single doses of 40–400 mCi [abstract].J Nucl Med 1992; 33: 784.Google Scholar
  4. 4.
    Ibis E, Wilson CR, Collier BD, Akansel G, Isitman AT, Yoss RG. Iodine-131 contamination from thyroid cancer patients.J Nucl Med 1992; 33: 2110–2115.Google Scholar
  5. 5.
    Nishisawa K, Ohara K, Ohshima M, Maekoshi H, Orito T. Monitoring of iodine excretion and used materials of patients treated with I-131.Health Phys 1980; 38: 467–481.Google Scholar
  6. 6.
    Jacobsen AP, Plato PA, Toeroek D. Contamination of the home and environment by patients treated with iodine-131: initial results.Am J Public Health 1978; 68: 225–230.Google Scholar
  7. 7.
    International Commission on Radiological Protection. 1990 Recommentations of the International Commission on Radiological Protection.Annals of the ICRP 1991: 21(1–3). Oxford: Pergamon Press, ICRP Publication 60.Google Scholar
  8. 8.
    O'Doherty MJ, Kettle AG, Eustance CNP, Mountford PJ, Coakley AJ. Radiatio dose rates from adult patients receiving131I therapy for thyrotoxicosis.Nucl Med Commun 1993; 14: 160–168.Google Scholar
  9. 9.
    Rose MR, Prescott MC, Herman KJ. Excretion of iodine-123-hippuran, technetium-99m-red blood cells and technetium-99m-macroaggregated albumin into breast milk.J Nucl Med 1990; 31:978–984.Google Scholar
  10. 10.
    Mountford PJ, O'Doherty MJ, Forge NI, Jeffries A, Coakley AJ. Radiation dose rates from adult patients undergoing nuclear medicine investigations.Nucl Med Commun 1991; 12: 767–777.Google Scholar
  11. 11.
    Crompton HM, Mitchell H, Cameron J McL. The Aberdeen formula.Nursing Times 1976; 26 August: 121–124.Google Scholar
  12. 12.
    Mountford PJ. Estimation of close contact doses to young infants from surface dose rates on radioactive adults.Nucl Med Commun 1987; 8: 857–863.Google Scholar
  13. 13.
    Singh B, Sharma M, Patel MC, Raghavendran KV, Berman M. Kinetics of large therapy doses of 131-I in patients with thyroid cancer.J Nucl Med 1973; 15: 674–678.Google Scholar
  14. 14.
    Ronga G, Fiorentino A, Pasiero E, Signore A, Todino V, Tummarello MA, Filesi M, Baschieri I. Can iodine 131 whole body scan be replaced by thyroglubulin measurement in the post-surgical follow-up of differentiated thyroid carcinoma?J Nucl Med 1990; 31: 1766–1771.Google Scholar
  15. 15.
    Culver CM, Dworkin HJ. Radiation safety considerations for post-iodine I131 thyroid cancer therapy.J Nucl Med 1992; 33: 1402–1405.Google Scholar
  16. 16.
    National Radiological Protection Board. Occupational, public and medical exposure.Documents of the NRPB, vol 4: no 2. London: HMSO, 1993.Google Scholar
  17. 17.
    Association of University Radiation Protection Officers.AUPRO Guidance Note No 3: Completion of RSA 3 Forms. University of Leicester, 1990.Google Scholar

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • S. F. Barrington
    • 1
    • 2
  • A. G. Kettle
    • 1
  • M. J. O'Doherty
    • 1
    • 2
  • C. P. Wells
    • 1
  • E. J. R. Somer
    • 2
  • A. J. Coakley
    • 1
  1. 1.Department of Nuclear MedicineKent and Canterbury HospitalCanterburyUK
  2. 2.St. Thomas' HospitalLondonUK

Personalised recommendations