1. The environmental dose measurements of high dose Iodine-131 treated thyroid cancer patients during hospitalization period
Nina TUNÇEL
 Department of Physics, Science Faculty, Akdeniz University, Antalya, Turkey

2. Introduction
Radioiodine mostly 131I is one of the oldest clinical radionuclide types which used widely spread in diagnosis and currently used in the treatment of both thyreotoxicosis and thyroid cancer.
Large doses of 131I are administered to ablate residual thyroid tissue and functional metastases from thyroid cancer.
Nina TUNÇEL

3. Introduction The regulations
In our country it is obligatory to hospitalize the patients receiving high doses of radioactive iodine, the same as European countries regulations. The limit for hospitalization that Turkey Atomic Energy Organization has defined is 800 MegaBecquerel (MBq). Hospitalization is required for patients receiving doses above this amount. However, the patients whose house conditions are not suitable and who will receive doses <800 MBq can be hospitalized(1). The Radioiodine (RI) (iodine-131, or 131I) activity is supposed to remain , <600 MBq in patients’ bodies or the external measurements received at the abdominal level from 1-m distance is required to be under 30 microSievert per hour (mSv/h) during their discharge(9). Additionally, in ‘protection from radiation guide, 97 Europe’ it was stated that this limit for the residual activity remaining in patient’s body needed to be 600 MBq or the external measurement value received from 1-m distance was required to be <30 mSv/h (2, 3).
1. Official Journal of Republic of Turkey (2000). Number 23999, Article 31.
2. European Commission. Radiation protection following Iodine-131 therapy (exposures due to out-patients or discharged inpatients). Radiation Protection 97 (Luxembourg: Office for Official Publications of the European Communities) (1998).
3. Jorgensen, H. B., Hoilund-Carisen, P. F. and Nielsen, V. E. External dose rates in radioiodine treatment of bening goitre:estimation versus direct measurement: Scand. J. Clin. Lab. I˙nvest. 66(6), 509–516 (2006).
Nina TUNÇEL

4. Therapy Patient with I-131
The patient should be kept at least 2h, and if possible one day in the hospital.
In the case of cancer treatment, the patient should generally be hospitalized for several days.
In all cases, the dose rate at 1 m from the patient should be down to an acceptable level established by the RPC.
Hospitalize:
>1100 MBq I-131
Release with restrictions:
Treatment of thyrotoxicosis
Pain palliation (Sr-89, Sm-153)
Lactating women (specified procedures)
Release without restrictions:
Diagnostic procedures
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5. IAEA Training Material on Radiation Protection in Nuclear Medicine
Room for Iodine Therapy (controlled area)
only one patient in the room
easily cleanable surfaces
and utensils
extra lead shields
door closed
warning sign outside
restrictions for visitors
decontamination equipment
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6. Exposures From Patient
Contamination External
saliva
perspiration
breath
urine
mSv/h
1000 MBq
I-131 m
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7. IAEA Training Material on Radiation Protection in Nuclear Medicine
Contamination
Administered activity: 1000 MBq I-131
Excretion Concentration Contamination
Saliva <2 MBq/g utensils 2 kBq
Perspiration <20 Bq/cm2 surfaces 10 Bq/cm2
Breathing Bq/l air 1 Bq/l
Urine < 500 kBq/ml toilet 2 kBq/cm2
Generally larger than the derived limits for contamination given by ICRP (publ 57)
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8. IAEA Training Material on Radiation Protection in Nuclear Medicine
Restrictions
Patient with Iodine-131
This is one example of behaviour restrictions
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9. IAEA Training Material on Radiation Protection in Nuclear Medicine
Restrictions
Patient with Iodine-131
And another one
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10. Estimated % of Administered I-131
I-131 Dosimetry NCCHPS

11. I-131 Dosimetry NCCHPS

12. IAEA Training Material on Radiation Protection in Nuclear Medicine
Isolation Ward
Bed shield is positioned
Areas are covered with plastic backed absorbent material.
King Faisal Specialist Hospital and Research Center, Riyadh
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13. IAEA Training Material on Radiation Protection in Nuclear Medicine
Discharge of Patient
Abdalla Al-Haj
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14. IAEA Training Material on Radiation Protection in Nuclear Medicine
Monitoring
Areas suspected to be
contaminated are surveyed.
Furniture and telephone sets
are surveyed.
King Faisal Specialist Hospital and Research Center, Riyadh
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15. IAEA Training Material on Radiation Protection in Nuclear Medicine
Monitoring
Derived limit: 3 Bq/cm2
METHODS
wipe testing
direct surveying
The measurements should be documented
The measurements should be documented
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16. Part 12. Protection of the public
Radiation protection in nuclear medicine
Structural Shielding
The absorbed dose is determined by factors such as:
source strength;
length of exposure;
distance from the source;
transmission through the protective barrier.
Patient with I-131
General public
This is an illustration of a situation where extra shielding might be necessary
D mSv/h
0.3 mSv/procedure
Distance d
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17. Materials and Methods
In the fixed activity protocol, a high activity typically 3.7, 5.5 and 7.4 GBq (100, 150 and 200 mCi) I–131 was administered to12 patients.
Therapeutic doses of 131I was administered orally in capsule form.
Nina TUNÇEL

18. Materials and Methods
In general, the patients remained in isolation for a period of 2–3 days.
Patients were confined to the two isolation rooms having walls covered with lead.
Each room is designed for two beds which were separated by a lead separator.
The special delay tank at hospital ground is designed for radioactive waste disposal.
Nina TUNÇEL

19. Treatment rooms
Entrance door
Corridor

22. Each treatment room has its own bath and toilet in room.
Nina TUNÇEL

23. Materials and Methods
The beta is often dominant radiation for I-131 treatments, although the associated gamma emission gives rise to exposures to other tissues and even to other individuals.
Nina TUNÇEL

24. Materials and Methods
The dose rates were measured at 1 m from the patient's thyroid and abdominal levels at different interval times.
The clean and unclean room dose rate measurements were performed at each isolated room.
Nina TUNÇEL

25. Materials and Methods
For environment dose measurements the dose rate meter (Inspector Radiation Alert, S. E. International, Inc., USA) was used.
Nina TUNÇEL

26. Therapy with <800 MBq I-131
Discharge of Patient
Therapy with <800 MBq I-131
External monitoring
30 mSv/h m

27. Results Discharge of Patient
mR/h at 1m
Day

28. Results Discharge of Patient
mR/h at 1m
Day

29. Results Discharge of Patient
mR/h at 1m
Day

30. Results Location The clean room overall 0.43+0.56 The toilet bowl
Dose rate + SD (mRh-1)
The clean room overall
The toilet bowl
The pillow
0.03 to 2.12
The unclean room overall
1.33 to 13
The pillow at unclean room
The background level was 0.014mRh-1 in the isolation area.
Nina TUNÇEL

31. Results Location Dose rate + SD (mRh-1) Surrounding rooms 7.06+10.33
Service door-corridor No
Pts.
Nina TUNÇEL

32. Date of survey?

33. Scanning at 7–10 d after therapy

34. I would like to thank the nuclear medicine department in Akdeniz University School of Medicine.