1. Planing a PET Imaging Centre: Radiological Protection Requirements
Dr. Radu A. Vasilache
Canberra Packard
Notes
3rd BALKAN CONGRESS OF NUCLEAR MEDICINE
“Present and future in Nuclear Medicine”
Bucharest, April 23rd-26th 2014

2. Overview Standards and legislation
What to survey? Pathways of exposure
Radiation protection planning
Specific instruments and methods for radiation monitoring
Conclusions

3. Standards and regulations
IAEA Basic Safety Standards & ICRP Guides and Recommendations
National laws and regulations: e.g. Law 111/1996 & Basic Radiological Protection Norms
Set up the dose limits for exposed personnel (20 mSv/year) and population (1 mSv/year)
Specific norms for each area of interest (nuclear medicine, environmental monitoring, personnel monitoring, site planning, etc.)

4. Who & What to Survey? Targets of the survey:
Protection of the profesionally exposed:
Direct exposure to external radiation – shielding calculations, dose monitoring
Internal exposure through inhalation & ingestion – internal contamination (activity) monitoring → zoning, doses are calculated
External contamination → zoning
Protection of the patients
Proper dosage
Dosimetry
GMP

5. Who & What to Survey? Protection of the public
Gaseous effluents (beta – gamma, pure beta)
Liquid effluents (beta – gamma, pure beta)
Waste disposal
External exposure

6. Radiation protection planing
Site planing:
Proper shielding:
Scanner
Hot room / preparation room
Injection rooms
Patients waiting rooms
Proper patients circuit: Entrance / reception / waiting hall → consult / preparation room → injection room / rest room → scanner → waiting room (post scanning) → exit.
Proper radiopharmaceuticals circuit: FDG reception → transfer to the hot room / dispensing → transfer to the injection room → disposal of the used syringes

7. Radiation protection planing
Site planing:
Proper facilities design:
Special ventilation
Special sewage
Waste disposal
Proper attendands circuits
Identify points of continuous monitoring and what needs monitored
Identify the proper equipment needs: basic / full / “de luxe”

8. Equipment needs Exposed personnel:
Basic: personnel dosimetry, proper personnel shielding (including hot-cells), contamination monitoring (hand-held)
Full: extra shielding, automatic dispensing (in some countries manual dispensing is not even allowed), automatic injection units
De luxe: hand – feet contamination monitors, extra alarming monitors
Patients:
Proper dosage: automatic dispensing is a must, manual dispensing is not nearly precise enough
Public: zoning, caution signs, physical barriers, proper effluent and waste handling

9. Equipment needs Patients:
Proper dosage: automatic dispensing is a must, manual dispensing is not nearly precise enough
The dispensed doses must be periodically veriffied by cross check with a second dose calibrator
Dose calibrators must be periodically submited to metrology verifications
Injected patients must be shielded from each other
Public: zoning, caution signs, physical barriers, proper effluent and waste handling

10. Personnel protection Personnel dosimetry:
Should be provided by an autorised personnel dosimetry lab (either with film badges, TLD badges or glass dosemeters), including extremity dosimetry
Minimum investment, records should be kept for a number of years speciffied by the national regulations
Extra dosimetry:
Electronic personal alarm dosemeters – some countries require that operating personnel should wear also alarm dosemeters and even keep the records
Area dosimetry & hand held contamination monitoring: also part of normal legal requirements, measurements fall into the responsibility area of the RPO

11. Examples of personnel dosemeters

12. Personnel contamination

13. Shielding
In order to minimise general exposure and especially hand exposure, automatic dispensing is compulsory
Hot cells for dispensers with 50 mm all arround lead shielding
Shielded syringes and automatic injectors also required
Images from

14. Patient protection Dosimetry:
Using the corect doses (activity measurement): dose calibrators, automatic dispensing
Internal dosimetry: easier said then done (biokinetic models, dose factors, etc.)

15. Patient protection Hot cells / dispensers: EEC GMP / GAMP conformity
2. ISO – Clearooms and associated controlled environments
3. ISO – Containment enclosures
4. FS209E Standard
5. Shielding requirements (minimum lead thickness, negative pressure, etc.)

16. Patient protection – hot cell design
Shielding
GMP conformity
- 2 pre-chambers
- Manipulation gloves
- Shielded dose calibrator
- Integrated waste conteiner
- UV lamp for sterilisation
- Double main door (lead and plexy)

17. Dispensing
Total activity measurement for the main / bulk vial and dilution to the desired initial concentration
Dispensing the syringe and diluting it to the desired concentration
Short dispening time

18. Dose dispensers
Images from

19. Dispensing and injecting
Mobile dispensing and injecting stations: careful not to allow direct connection between the main vial and the patient
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20. Dispensing and injecting
Mobile dispensing and injecting stations (e.g. Karl-100):
- should allow dispening into a syringe (dispensing the dose directly to the patient presents the risk that a malfunction will put the patient in direct contact with the main vial, which would be contrary to the GMP, and exposes the patient to an useless external dose)
- should allow independent verification of the dispensed dose
- should allow with the minimum possible injected volume (e.g. not more than 10 ml)
-should allow for any lead pot to be used to avoid un- necessary exposure of the personnel when transfering the vial from one pot to the other

21. Dosimetry – area monitoring
Ambient equivalent dose H*(10)
Measured directly, usualy the dose, time stamp and location are logged in
Usually applies to photons (gamma & X) and neutrons, surface contamination is subject to separate monitoring and should lead to zoning
Area monitoring normally involves network monitoring, with detectors sending remotely the data, combined with periodic surveys performed by operators

22. Zoning The access to different areas should be subject to zoning
At least 3 zones are normally established:
Controlled area: personnel doses could reach and exceed a higher level (e.g. 6 mSv/year) & external contamination may occur
Buffer zone: doses are above background, but will not exceed a determined level (e.g. 3 mSv/year) contamination should not occur
Free on-site access zone, where doses should be in the background level, and contamination must not occur

23. Area monitoring – hand held units

24. Details to be observed
Dose ranges: in areas where the dose rate could have significant fluctuations, a matter of concern should be the saturation of the probes
TTC methods is the answer

25. Time – to – count principle
Conventional GM Tube Operation
BIAS
+HV
TIME
DISCR.
WAVE FORMS
TIME
PULSE
TIME
Source

26. Time – to – count principle
“Time to Count” Operation
t on
t on
Time Totalizer HV ÷
Average Time to Count HV 2
t off
Pulse Totalizer
t off K
TIME TO COUNT
RATE =
TIME
GM TUBE WAVEFORMS
Source

27. Time – to – count principle
“Time to Count” Behaviour
HIGH FIELD
LOW FIELD
SHORT TIME
+HV
+HV HV HV 2 2
LONG TIME
2 mSec.
2 mSec.
TIME
TIME
Source

28. Effluent & waste monitoring
Should be integrated in the same RMS software as the dose area monitoring
Involves mostly liquid discharges (gaseous effluents are not a big concern in sites without cyclotrons)
Waste:
Solid:
Can be stored in a shielded place until cold
Biohazard must be addressed
Liquid:
Separate sewage needed
Dilutors are to be used until the sewage waste is cold then treated according to normal hospital regulations

29. Conclusions
From the point of view of the radiological protection, one must observe the following in the site planing:
Plan for the correct circuits for patients, incoming FDG and attendants
Insure proper zoning
Insure proper monitoring of personnel exposure / contamination
Monitor waste production
Never use manual dispensing
Always check the doses dispensed by periodic cross - measurements

30. Thank you!
...for your attention...
Questions?