1. Which protection against radiation from new protocols of internal dosimetry by yttrium-90
AUBERT Bernard*, GUILABERT Nadine°, LAMON Annick* and RICARD Marcel*
*Physics Department and °Nuclear Medicine Department
Institut Gustave-Roussy, Villejuif, France
6th European ALARA Network Workshop - Madrid, 23-25/10/2002

2. Introduction
Within the field of the therapeutic applications in Nuclear Medicine, new protocols have been proposed these last years based on the use of therapeutic agents labelled with yttrium-90 :
Octreother° (somatostatine analogue) on patients with neuro-endocrines tumors.
Zevalin* for treatment by radio immunotherapy of non Hodgkiniens lymphoma.
° Mallinckrodt
* Schering

3. Yttrium 90 - ( 100 %) T1/2 = 64.1 hours Rmax (air ) : 9 m
Rmax (water) : mm
R90 (water) : 5.3 mm

4. Introduction
iode 131 : beta emitter (Emax  0.6 MeV) used since more than 50 years for treatment of thyroid diseases and gamma emitter (Eprincipal = MeV):
Radiation protection procedures are well known even for high activities ( 8 GBq).
Other used beta emitters:
erbium 169 (Emax  0.35 MeV)
rhenium 186 (Emax  1 MeV)
Applications not very wide spread and using low activity ( 0.1 GBq).

5. Aim of the study
Recommandations for radiation protection for beta emitters are very general:
10 mm of PMMA are enough to stop any beta emission,
PMMA is preferable to lead (or tungsten) because the bremsstrahlung emission is less important.
Systematic analysis of exposure situations at the beginning, or before starting, clinical protocols with yttrium-90 by:
procedure analysis,
choice of radiation protection material, and,
additional dosimetric survey.

6. 71.1 µSv.h-1.GBq-1
43.5 Sv.h-1.GBq-1
Radiation Protection Dosimetry, Vol. 98, No 1, 2002

7. Additional personal dosimeter
TLD chips
Electronic dosimeter

8. OCTREOTHER protocol Solution of 5.4 GBq (145 mCi) of 90Y in 86 mL
Activity measured with a dose calibartor
Radioactive vial placed inside the injection container

9. OCTREOTHER protocol Installation of the line
Connection of the line to the patient
Installation of the line in the electrical pump
Injection of 4.44 GBq (120 mCi) by perfusion during 12 to 15 minutes

10. OCTREOTHER protocol Surveillance of injection
Collection of vial and line and management of radioactive wastes
Surveillance and patient care during 2 days

11. OCTREOTHER protocol
Exposure measurements with portable ionisation chamber
Close to the delivery container and injection container (at  5 cm):  300 µSv/h.
at 1 m from containers:  2 à 3 µSv/h
Before injection :
After injection
at 1 m from patient:  30 à 40 µSv/h
near the second pump (for amino acides) managed by the nurse:  120 µSv/h

12. Finger exposure in mSv/injection TLD measurement - mean value (SD)
OCTREOTHER protocol
Finger exposure in mSv/injection
TLD measurement - mean value (SD)
Localization
Technologist
1st injection
right thumb
18.0
right forefinger
23.5
left foerfinger
14.5
left
thumb
14.0
After new procedure
Technologist
(15 inject.)
Nurse
2.81
(2.13)
0.40
(0.56)
2.36
(2.58)
0.28
(0.50)
2.12
(0.74)
0.42
(0.58)
1.6
0.20
(0.32)

13. (dose rate at 1 m: 1.5 to 2 µSv/h).
OCTREOTHER protocol
NaI(Tl) probe
Bremsstrahlung spectrum from patient one day after injection of 4.44 GBq of 90Y
(dose rate at 1 m: 1.5 to 2 µSv/h).

14. OCTREOTHER protocol
Due to the importance of low energy components in the bremsstrahlung spectrum (max at  80 keV and very few photons above 300 keV), a protective apron (0.5 mm Pb equivalent ) is efficient.
Measurement with portable ionization chamber
(RAM DA 2000)
Patient 1 (at 50 cm)
Patient 2 (at 65 cm)
without apron
360
59.1
with apron
4.8
1.0
(µSv/h)

15. ZEVALIN protocol Radionuclide preparation.
Injection of 1.11 GBq (30 mCi) with an automatic syringe pump during 10 minutes.
Surveillance of injection.
Collection of vial and line, and management of radioactive wastes.
Surveillance and patient care during 2 days.

16. ZEVALIN protocol Radiopharmaceutical preparation
Solution of 1.85 GBq (50 mCi) of 90Y in 2 mL.
Measurement of activity with a dose calibrator.
Removal of 90Y from delivery vial and transfer into preparation vial.
Filling of infusion syringe.

17. ZEVALIN protocol Efficiency of vial shield
Wall in lead glass and size adaptator in PMMA
Close to the shielding:  70 µSv.h-1.GBq-1

18. ZEVALIN protocol
Syringe shield
Tungsten
 5 mm
PMMA
5 and 10 mm

19. ZEVALIN protocol Efficiency of syringe shield - TLD measurements
This study
5.5
ZIMMER* study
11.2
Contact syringe
(mSv.h-1.MBq-1)
Contact with syringe shield
(µSv.h-1.MBq-1)
PMMA-5 mm
PMMA-10 mm
tungsten-5 mm 16
2.7
1.4
PMMA
PMMA/Pb
tungsten
2.8
1.7
2.4
* Zimmer et al., abstract n° 164, J.N.M. abstract book, may 2002

20. Conclusions
This radiation protection study concerning new therapeutic protocols with 90Y confirmed:
the need for studies related to working conditions before the starting of new clinical protocols,
the interest of additional dosimetry at the most exposed regions (fingers),
the interest of operational dosimetry for the direct information of the operator,

21. Conclusions
the need for electronic dosemeters suited to the situation, i.e. sensitive to the beta radiation,
the need to collaborate with the manufacturer to increase its awareness of this problem in order to inform users before starting the clinical protocol,
the contribution of a radiation protection culture in a hospital where the human and material means are available.