«RADIATION DOSE RATES FROM PATIENTS RECEIVING IODINE-131 THERAPY IN THE RABAT CHU» T.KALONJI, A.ELYAHYAOUI, S.BOUHLASSA, F.IMANI, N.

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1 «RADIATION DOSE RATES FROM PATIENTS RECEIVING IODINE-131 THERAPY IN THE RABAT CHU» T.KALONJI, A.ELYAHYAOUI, S.BOUHLASSA, F.IMANI, N.BEN RAIS

2 INTRODUCTION

3 The standards in use in our service impose a five days stay for the patients having received an amount from at least 1,1 GBq. It is interresant to note that in these standards the patient is regarded as a point source of iodine 131, placed at 1 meter of distance of its close relations during eight hours per day and outputting an amount of irradiation limited to 5 msv.

4 It appears thus that this estimation of the duration of hospitalization takes account only of the radioactive decrease of administrered dose which depends only on the physical radioactive half-life of the iodine 131. This estimation is still used in several centers of irratherapy.

5 However the Advisory committee of protection against radiation (CCRP) and of the Group of the medical advisers (GCM) of CANADA recommend that the determination of radioactivity dose must take in consideration that the patient is a diffuse source (not point source), which attenuating properties are more considrable than a point source.

6 Taking into account these considerations, the present study aims to carryout a follow-up of dose rate of irradiation of the patient during his hospitalization, in order to appreciate with precision, the time in which it ceases to constitute a danger of irradiation for the neighbouring people.

7 The obtained results will make it possible to reduce the stay duration in the radio protected room and to optimize consequently the the use of human and material means of the service.

8 MATERIAL, PATIENT AND METHOD

9 MATERIAL: In this study the material used is: Two radio protected rooms equipped each one with toilets with a WC connected to the tanks of radioactivity decrease. Mural rate meter Leaded blouse The leaded folding screen A card of investigation

10 PATIENT: The measurements of dose rate are realized among patients treated for thyroid cancer in the service of nuclear medicine of the Avicenne hospital. 72 files were selected for this study; The patients brek down as follow: - female sex (91%), - Age in the range of 30-40years

11 Originating from all the areas of Morocco (90%) and the inhabitants of Rabat 10% of the sample studied.

12 METHOD: The selection of the population of the patients was made on the basis of following criterion: To be treated for thyroid cancer in the service of nuclear medicine of the CHU of Rabat. to have an accessible medical file;

13 To have transitorily stop its treatment by thyroid hormones for a least duration of 4 weeks To have made the biological chek-up of TSH us and Tg.

14 During the hospitalization of the pathients whose files were selected, we measured the dose rates at the 48 th,72 th and at the end of their hospitalization (at 120 th hour) Measurements are realized respectively at distance 1 meter and 2 meters from the patient

15 RESULTATS

16 DISTRIBUTION OF THE PATIENTS BY SEX

17 REPARTITON OF THE PATIENTS BY SLICES OF AGES 50,00% 40,00% 30,00% 20,00% 10,00% 0,00% ans ans ans ans ans ans ans

18 LEVEL OF SOCIAL LIFE OF THE PATIENTS

19 PROPORTION OF THE PATIENTS AT THE METASTASES STAGE

20

21 48 th hour 72 th hour 13,086 5,529

22 48 th hour 72 th hour 4,592 2,079

23 AT THE AND OF HOSPITALISATION 2,013

24 DISCUSSION

25 The data analysis obtained show that the rate dose measured at different distances are not inversely proportional to reciprocal of the square of the distance (tables 1 and 2); This observation allows us to affirm that the patients behave like a non point source; This is due to the fact that the radioactivity injected is distributed in the blood of the examined patients.

26 In addition we note that the average of the dose rates measured at the 48 th hour, at a distance of at 1 meter of the patient, is about 13.08µSv/H which is approximately equal to the low threshold ( 200 MBq)

27 This low radioactivity at the 48 th hour is due to the fact that : The patients have all undergoes the operation of the thyroid and there is just an minor amount of thyroid parenchyma thet remains; In addition it has been known that the process of fixing iodine is disturbed on the sick or tumoral thyroid parenchyma which does not concentrate iodine, From where, only a small proportion of administered activity was fixed;

28 The value of this residual activity of 200 MBq measured at the 48 th hour corresponds to that authorizing the end of the hospitalization of the patient with a restriction period of 7 days. (the 97/43/EURATOM directive)

29 The patient leaving authorized after the 48 th hour instead of 120 th hour, has the following advantages: The service will hospitalizes 192 patients per yaer, instead of 96 patients, as it is currently the case; The reduction of the waiting period of the programmed treatments which will pass from 2 years to 1 year;

30 It makes it possible to avoid prolonging the isolation of the patient unnecessarily. This can influence much the moral of the patient as well as his family. Because, this protocol of insolation gives the impression to the patients that they have a threatening disease and a dangerous treatment; what justifies the resentment.

31 Taking into account the sociocultural conditions of our patients, the treatment in external private clinic seems not to be a possible solution.

32 CONCLUSION

33 It has been schown from this results that: 1. That it is possible: To make the available radioprotected rooms profitable at a maximum; To reduce for many patients the waiting periods of the treatment; To avoid unnecessarily prolonging insolation of the patient which can influence much more the moral of the patient as well as his family. 2. That the treatment in external private clinic is not a still possible solution.

34 REFERECES

35 1. Barrington, S.F., Kettle, A.G., O'Doherty, M.J., Wells, C.P., Somer, E.J.R., and Coakiey, A.J. "Radiation Dose Rates from Patients Receiving Iodine-131 Therapy for Carcinoma ofthe Thyroid." European Journal of Nuclear Medicine. Vol. 23, No.2, February Barrington, S.F., Kettle, A.G., Thomson, W.H., Burrell, D.N., Batchelor, S., Mountford, P.J., O'Doherty, M.J. and Harding L.K. "RCP Guidelines on Radiation Protection Following Radioiodine Therapy for Thyrotoxicosis: Are they Appropriate? (abstract)". Nuclear Medicine Communications (1996) Vol. 17; Carey, J.L., Kumpuris, T.M. and Wrobel, M.C. "Release of Patients Containing Therapeutic Dosages of Iodine-131 from Hospitals. Journal of Nuclear Medicine Technology. Vol. 23, No. 23, pp , September Caldwell, C.B. and Ehriich, L.E. Outpatient Treatment ofthyroid Cancer Using High doses oflodine 131, Canadian Association ofradiologists Journal, Oct vol. 50 no. 5 pages Culver, C.M., Dworkin, H.J. "Radiation Safety Considérations for Post-Iodine- 131 Thyroid Cancer Therapy". Journal ofnuclear Medicine, Vol. 33, No. 7: , July "Lignes directrices sur la gestion des patients traités à l'iode 13l", Groupe des conseillers médicaux auprès de la Commission de contrôle de l'énergie atomique, mars 1993, ÎNFO-0442.

36 7. Monsieurs, M., Thorons, H., Darks, R-, De Bacre, E-, De Ridder, L., De Saedeleer, C., De Winter, H., Lippens, M., Van Imschoot, S-, Wulfrank, D., Simons, M. Coordinating centre: University Hospital, Gent, Belgium. "Real-life Radiation Burden to In-living Relatives of Patients Treated with for Benign and Malignant Thyroid Disease: a Multicentre Study in 8 Centres for Flanders (Belgium)". (Abstract # Poster Session) at 45ihAnnual Meeting ofthe Society of Nuclear Medicine, June 1998 (Toronto). 8. Radiation Protection Following lodine Therapy (Exposures Due to Outpatients or Discharged Inpatients), Luxembourg: European Commission, (Radiation Protection séries no. 97). 9. Siegel, J.A. "Outpatient Radionuclide Therapy." Proceedings of the Thirty-Fifth Annual Meeting ofthe National Council on Radiation Protection and Measurements. Proceedings No. 21 April Wasserman, H.J. and Kiopper, J.F. "Analysis of Radiation Doses Received by thé Public from ml Treatment ofthyrotoxic Outpatients". Nuclear Medicine Communications (1993) 14, Working Party ofthe Radiation Protection Committee ofthe British Institute of Radiology. "Patients Leaving Hospital after Administration of Radioactive Substances." BJR Feb 1999 pp