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

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

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.)

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

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

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

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”

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

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

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

Examples of personnel dosemeters

Personnel contamination

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 www.temasinergie.com

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

Patient protection Hot cells / dispensers: EEC GMP / GAMP conformity 2. ISO 14644 – Clearooms and associated controlled environments 3. ISO 10648 – Containment enclosures 4. FS209E Standard 5. Shielding requirements (minimum lead thickness, negative pressure, etc.)

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)

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

Dose dispensers Images from www.temasinergie.com

Dispensing and injecting Mobile dispensing and injecting stations: careful not to allow direct connection between the main vial and the patient Images from www.temasinergie.com

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

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

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

Area monitoring – hand held units

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

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

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 www.canberra.com

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 www.canberra.com

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

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

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