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DESIGN OF THE FIRST UNIT OF PET-CT IN MOROCCO BUILDING REQUIREMENT and SAFETY EQUIPMENT-

DESIGN OF THE FIRST UNIT OF PET-CT IN MOROCCO BUILDING REQUIREMENT and SAFETY EQUIPMENT-. a R. Cherkaoui El Moursli, b A. El kharrim, c K. Talsmat, a Y. Toufique, d Verra. P irlet

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DESIGN OF THE FIRST UNIT OF PET-CT IN MOROCCO BUILDING REQUIREMENT and SAFETY EQUIPMENT-

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  1. DESIGN OF THE FIRST UNIT OF PET-CT IN MOROCCOBUILDING REQUIREMENT and SAFETY EQUIPMENT- aR. Cherkaoui El Moursli, bA. El kharrim, cK. Talsmat, aY. Toufique, dVerra. Pirlet a) Mohammed V-Agdal University, Faculty of Science, Morocco b) National Center of Scientific and Technical Research, Morocco, (c) Center for Energy, Sciences and Nuclear Techniques, Morocco , (d) Federal Agency for Nuclear Control, Belgium THE 13th International Congress of the IRPA Glasgow, May 13-18, 2012 

  2. Introduction and objectives (1/2) • Positron emission tomography, also called PET imaging or a PET scan, is a type of nuclear medicine imaging. • PET-CT offers the potential to identify disease in its earliest stages as well as a patient’s immediate response to therapeutic interventions. • Clinical Applications of PET/CT • Oncology • Cardiology • Neurology currently oncology procedures far outnumber all other clinical indications

  3. Introduction and objectives (1/2) • The aim of this work is to present the method adopted to ensure radiation protection, the Safety and Security for the first PET-CT installed in Morocco at Anoual Radiology Center in Casablanca • Both distance and shielding must be determined to good effect for the purpose of radiation dose reduction for staff and the public.

  4. PET/CT technology, operational principles • Introduced FDG into body by intravenous injection • Decays of the radioactive atom. • A positron is ejected leading to emission to 511 keV photons • A set of detectors surrounds the object to be imaged radionuclide 18F-FDG , an analogue of glucose: Fluorine -18 fluorodeoxyglucos

  5. Radiation Protection Issues Difference from standard Nuclear Medicine 99mTc -140 keV photons - standard Nuclear Medecine PET- radionuclides - 511 keV photons Because 511 keV photons are more penetrating than the 140 keV photons, more stringent protective measures are required for a PET facility compared to a conventional nuclear medicine facility

  6. Protection Considerations • PET - Penetrating photons we must take into account of: • Staff doses • Doses in adjacent areas • Facility design • Protection equipment • Heavier shielding needed at hot lab • CT • Patient doses • Scattered radiation for persons in CT room

  7. Calculation of shielding for PET • Two possible scenarios: • Calculation of dose rate based on a F-18 point source (without absorption by the patient) • Calculation of dose rate based on a real situation (patient standard) • Common Data used for the two scenarios: • Use rate of the examination room (5 days / week or 40 hours / week) • half-value layer (HVL) = 5 mm Lead or 51 mm Concrete or 35 mm Baryte Concrete • Occupancy rate of the control (T = 100%).

  8. Calculation of dose rate based on a point source • Data : • Dose rate at 1 m for an activity 1MBq: 0.160 μGy / h • Maximum injected activity: 370 MBq (10 mCi) • Dose rate at 1 m for an activity of 370 MBq per week: 370x0.160 μGy / hr x 40 hours = 2369 μGy / week (midpoint of the gantry) • Calculations : • Dose rate at 1m for a 370 MBq source activity : 2369 µGy/week • Dose rate at 5 m for a 370 MBq source activity: 2369/25 = 94,8 µGy/week • From 94,8 µGy/week, we must reach 20 µGy/week (=1mSv/year for public) CDA = ln 2 / µ = 0,693/µ 20 / 94,8 = 0,21 = ln 0,21 = -0,138 x x= 1.13 cm of Pb or x=11,4 cm of concrete

  9. Calculation of dose rate based on a real situation (standard patient) • Data used: • 18F Source • Number of examinations per day: 15 (30 minutes/patient) • Consideration of radioactive decay (examination 1 hour after injection) • The attenuation by the patient consideration (50%) • Dose rate at 50 cm from the patient: 35 μGy / h (ref) • Consideration of a safety factor of 1.5 (15 patients + 7)  35 x 1,5= 52.5 μGy / h to 50 cm

  10. Calculation of dose rate based on a real situation (standard patient) • Results • Dose rate at 1 m over a week: 13.12 μGy / hr x 40 hours = 525 μGy / week (Central point of the gantry) • Dose Rate to 5 m (our installation) over a week: 525/25 = 21 μGy / week • Dose limit to be respected: 20 mSv / week (for public) • The shielding is not really required in these conditions at 5 m distance. For optimization, we can however recommend a minimum of shielding. For example one or two HVL ordinary concrete, which gives us 5 cm or 10 cm.

  11. Safety equipment Syringe shields (W≥5 mm) in sizes to fit all the syringes used for administration of doses Shielded trolley (Pb, 30 mm) to move shielded syringes from the hot laboratory to the administration room Shielded hot cell and dose calibrator (50 mm (Pb) to avoid whole-body exposure

  12. Safety equipment (next) Manual injection Operating camera from gantry Automatic injection Lead mobile screen (≥30 mm) highly recommended to reduce whole-body Exposure when standing next to the patient (injection process, removal of cannula) or when operating the scanner from the gantry. The introduction of automated dispensing and injection during PET procedures: a step in the optimisation of extremity doses and whole-body doses of nuclear medicine staff

  13. Safety equipment (next) Monitoring of occupational exposure Personal whole-body dosimeters Ring dosimeters All staff working in a PET-CT facility must wear a personal dosimeter (OSL, TLD, film badge, electronic dosimeter) . In addition, staff preparing and injecting FDG doses should wear finger dosimeters to demonstrate that equivalent doses do not exceed the annual limit of 500 mSv .

  14. Requirement • Staff should be outside the scanning room (in a control room as with CT scanning), not inside the PET scanning room during acquisitions PET/CT Control Room PET/CT, Exam Room and Control Desk

  15. Conclusion • The shielding requirements for a PET facility are different from those of most other diagnostic imaging facilities. • This is due to the high energy of the annihilation radiation and the fact that the patient is a constant source of radiation throughout the procedure. • Meeting the regulatory limits for uncontrolled areas can be an expensive proposition. • Careful planning with the equipment vendor, facility architect, and a qualified medical physicist is necessary to produce a cost effective design while maintaining radiation safety standards.

  16. REFERENCES 1. Moroccan Décret N° 2-97-132 du 28 octobre 1997 relatif à l'utilisation des rayonnements ionisants à des fins médicales ou dentaires. (Bulletin officiel, 4 décembre 1997, N° 4540, p. 1025 à 1028) 2.International Commission of Radiation Protection. Radiation dose to patients from radiopharmaceuticals. ICRPPublication 80. 3.European Commission (EU). European Guideline on Quality Criteria for Computed Tomography, Report EUR 16262 EN. 1999. 4. International Atomic Energy Agency (IAEA). Quality Assurance for PET and PET/CT Systems:IAEA Human Health Series No. 1. Vienna, 2009. 5. American Association of Physicists in Medicine (AAPM). Specification and Acceptance Testing of Computed Tomography Scanners. College Park, Md: American Association of Physicists in Medicine; AAPM Report 39, 1993 6. American College of Radiology. Nuclear medicine/PET accreditation program requirements. Available at: http://www.acr.org/s_acr/bin.asp?CID51744&DID5 12152&DOC5FILE.PDF

  17. Thanks for your attention rcherkao@fsr.ac.ma rcherkao@cern.ch

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