Co-60 irradiator for therapy level calibrations at SSDLs

Transcription

1 SPECIFICATION Co-60 irradiator for therapy level calibrations at SSDLs Prepared by: Igor Gomola, Technical Officer for TC Project ISR6021 Date: 2014-Aug-04, Rev.08 Page 1

2 1. Scope and Background This document highlights the main technical requirements of a Co-60 irradiator for therapy level calibrations to be installed at the SSDL of Israel in the framework of the IAEA Technical Cooperation project ISR6021. Aim of the project is to establish a Secondary Standards Dosimetry Laboratory (SSDL) for reliable calibration and verification of dosimetry equipment. The layout of the SSDL of Israel is included in Appendix Applicable documents [1] INTERNATIONAL ATOMIC ENERGY AGENCY, Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards General Safety Requirements Part 3 No. GSR Part 3 (Interim) ISBN , Vienna 2011 [2] INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Sealed radioactive sources - General, ISO , ISO, Geneva, (1977). [3] INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Sealed radioactive sources - Leakage test methods, ISO/TR 4826, ISO, Geneva, (1979). [4] INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Sealed radioactive sources - Classification, ISO , ISO, Geneva, (1980). [5] INTERNATIONAL ATOMIC ENERGY AGENCY, "Calibration of Reference Dosimeters for External Beam Radiotherapy (TRS 469), Technical Report Series No. 469, IAEA, Vienna (2009), [6] INTERNATIONAL ATOMIC ENERGY AGENCY Radiation Protection in the Design of Radiotherapy Facilities: SAFETY REPORTS SERIES No. 47, ISBN , Vienna, 2006, [7] INTERNATIONAL ELECTROTECHNICAL COMISSION (IEC), Medical electrical equipment Part 2-11: Particular requirements for the basic safety and essential performance of gamma beam therapy equipment, IEC , Geneva, (2013) [8] INTERNATIONAL ATOMIC ENERGY AGENCY Measurement Uncertainty A Practical Guide for Secondary Standards Dosimetry Laboratories, AEA-TECDOC-1585, Vienna 2008, 3. Abbreviations and definitions CBA: Central Radiation Beam Axis FS: Field Size (defined at 50% isodose) Gy/min: Gray per minute (absorbed dose rate to water) SDD: Source to Detector Distance Site: the SSDL of Israel, located in the Sheba Medical Centre at Tel Hashomer SSD: Source to Surface Distance SSDL: Secondary Standards Dosimetry Laboratory Penumbra: The penumbra is defined as the lateral distance between 80% and 20 % relative dose values normalized to the dose value at the CBA. Page 2

3 4. Requirements 4.1. General requirements All items provided shall be new. No refurbished items are allowed. The following general requirements should be fulfilled: Irradiator to be operated through a remote control panel The remote control panel should include a digital timer for documentation of actual exposure time and for precise termination of irradiation, and an emergency stop button The irradiator should be properly shielded for the type of source included in the irradiator, following the International Basic Safety Standards [1]. The sealed sources have to comply with ISO guidelines [2,3,4]. Radiation leakage through the head shall be in compliance with the IEC standards [7] Fail-safe design: in case of power failure, source to go back automatically to its safe storage place Connection to various safety interlocks (door switch, door eye beam, radiation monitor signal) to avoid unintended exposure of staff 4.2. Performance requirements All performance specifications and tests shall comply with the relevant standards of the IAEA, IEC and ISO, specified in the references [herein, see chapter 2] 4.3. Technical specification Irradiation geometry Irradiator head should be mounted on a support stand allowing horizontal radiation beam geometry (see Fig.1). The system should allow stable and reproducible alignment of the Co-60 head in both, horizontal and vertical directions, with respect to the central radiation beam axis (CBA). The CBA should be between 100 and 130 cm above the floor. Fig.1. Schematic drawing of a typical calibration setup for therapy level calibration. Please note the calibration bench and water phantom are not included in this specification. Page 3

4 Radiation source (a) Co-60 source (b) Source activity up to 10 kci (c) Source diameter < 25 mm (d) Double steel encapsulation (e) Minimum warranty for the source > 10 yrs Collimators (a) Source housing, which includes the primary beam collimator to prevent unwanted radiation emission. (b) Secondary collimation system to define the radiation field at the given SSD by means of the two pairs of jaws (horizontal and vertical). Collimator jaw position indication, either mechanical or electrical (c) As an option: a. Collimator rotation at least + 100, manual or remote control b. A transparent shadow tray for secondary collimation to support blocks up to 20 kg Radiation field The radiation field should have the following characteristics: (a) Minimum field size at SSD=100 cm: < 5cm x 5cm (50% isodose level) (b) Maximum field size at SSD=100 cm: > 30cm x 30cm (50% isodose level) (c) Achievable penumbra at 5 cm depth at SSD=100 cm in water < 2 cm. (d) Uniformity of + 3 % over 80 % of the field (e) Symmetry better than + 3 % (f) Beam output > 1.5 Gy/min at a depth of d max for a 10cm x 10cm field at SSD=100 cm during the acceptance test (g) Beam output reproducibility < 0.1 % on CBA (standard uncertainty of the distribution of a series of about ten measurements, after all necessary corrections applied, assuming a measurement time more than 20 seconds) (h) As an option: o field light simulation with the congruence < 2 mm to the radiation field o optical distance indicator (accuracy within 2 mm between 80 and 120 cm range) The Co-60 irradiator shall be operated from a remote control panel located in the control room. The control system of the irradiator should have the following features: (a) Prescribed exposure time (from seconds to several hours with the time resolution < 0.1 sec) (b) Relative uncertainty of the beam timer < 0.1 % [8] (c) Display actual value of exposure time (d) Display status of all interlocks (e) Remote control of the beam shutter (On/Off) by selected exposure time (f) Emergency stop button (g) Indication of radiation beam (On/Off) (h) Connection to various safety interlocks (door switch, door eye beam, radiation monitor signal, laboratory safety circuits) to avoid unintended exposure of staff (i) PC interface allowing the control unit a remote controlled operations (j) Record system storing information on the use and status of the irradiator (date, time, irradiation time, interlock status, ) An Uninterruptable Power Supply (UPS) to immediately retract the source, close the collimators and maintain the control console information at the time of a power outage A manual source retraction device should be provided with clear instructions appropriate to the operation thereof Page 4

5 The unit shall operate with a mains voltage of 220V at 50 Hz. An appropriate power stabilizer shall be provided if required A laser alignment system to define the radiation central beam axis should be mounted in the irradiaton room. The line width of the laser beam should be less than 1 mm Safety items The Co-60 irradiator must be safe to operate and must be designed to prevent any unintended exposure to staff. The safety system shall be an integral part of the calibration system Interlocks provided for the irradiation room entrance door combined with at least two photoeyes mounted at the entry to the room (i.e. in the maze) to stop the source exposure when (i) the door is open, and/or (ii) photoeyes are activated Audio-visual radiation alarm monitors at the control panel and near the entrance to the bunker Radiation monitor for workplace monitoring to be installed in the calibration room. The display should be located outside of the irradiation room (in the control room) and indicate radiation exposure in terms of Sv/hr (micro Sv per hour). A visual and audible alarm signals shall be initiated, when the Co-60 beam is ON (exposure rate in the irradiation room is elevated) Video color surveillance system: 2 cameras with wide-angle lenses and wall mounts (each camera to survey 2/3 of the irradiation room) connected to 2 monitors located in the control room Emergency stop switches should be installed at several locations including the control console, along the maze and in the calibration room The entrance to the maze should be fitted with a dual interlock system to prevent radiation exposure when it is trespassed or incompletely latched. 5. Compliance to applicable international safety standards The contractor shall provide evidence of compliance to international safety standards specified in Section 2 Applicable documents. 6. Replacement and management of decayed source The Contractor agrees to accept and manage the source disposal at the end of its useful life. The terms, conditions and pricing for this service shall be negotiated separately between the Parties and shall be in accordance with the industry practices at that time. 7. Marking The system should have the safety marking as required by international standards given in section 2 Applicable documents. The System shall have all safety markings in the English. 8. Transportation and Packing The System shall be packed in accordance with international standards as applicable for the mode of transport chosen. The Contractor shall take care of shipment and transportation to the Site of the System and all necessary tools. The Contractor shall also be responsible for the transportation and delivery of the Co-60 source to the Site. 9. Quality requirements Page 5

6 The System shall be manufactured, shipped and installed in accordance with the ISO 9000 quality assurance system or equivalent. The Contractor shall document the compliance with this quality assurance system. 10. Accompanying documents Performance specifications Operating instructions Installation instructions Preventive maintenance and service manual Installation requirements Acceptance testing protocol 11. Site preparation and readiness The contractor acknowledges that at the time of signature of the Contract the radiotherapy center at the Site is under construction. The Site is expected to be ready in June The completion date will be communicated by the IAEA to the Contractor in due time to start the execution of the Contract activities. Notwithstanding any authorization given by IAEA, the Contractor shall visit, inspect and ascertain that all necessary conditions are met at the Site before starting any activities. Any comments or suggestion as regards the conditions of the Site shall be made before initiating the installation activities. The Contractor shall also check and ensure that any tool or local staff, as necessary for the work, is available at the Site. 12. Testing and Acceptance Factory Acceptance Test The System prior to shipment shall be tested for conformance of the System with manufacturer s performance specifications and the minimum requirements specified herein. The results of the testing of the System shall be documented by the Contractor in a Factory Testing Report to be provided to the Agency before shipment to the Site. On site Acceptance Test The System after installation shall be tested by the Contractor together with the SSDL physicist at the Site to demonstrate that the performance meets the manufacturer s performance specifications and the minimum requirements specified herein as determined by the IAEA and the End-User. A minimum of 6 weeks prior to installation, the Contractor shall notify the Agency, which retains the right to depute an IAEA representative to be present at the Acceptance Test at the Site. The results of the testing of the System shall be documented by the Contractor in an acceptance protocol that shall be co-signed by the SSDL physicist and the Contractor s representative. This document shall be dated and accepted as the start of the equipment warranty period. A copy of the acceptance protocol shall be sent to the IAEA. 14. Warranty and service Page 6

7 14.1. The System and all components shall be covered by one-year full warranty including parts and labor, starting as of the date of successful on-site acceptance, as per Section 12 above. Warranty shall also cover hardware and software, including further safety and functionality upgrades and updates. Warranty shall include all necessary spare parts, shipment to site, cost of replacement (work, personnel etc.) and disposal of faulty parts Training for in-house engineers on the first line maintenance and troubleshooting should be provided Availability of manufacturer service at national or regional level (address of the nearest service location, number and qualification of the maintenance engineers in that location should be indicated) The Contractor shall guarantee that replacement parts are available for at least 10 years after installation of the Co-60 irradiator The Contractor shall ensure that service support and further upgrades of the system are available 14.6 The Contractor should indicate maximum time needed for a service representative to arrive to the SSDL location (Sheba Medical Centre in Tel Hashomer near Tel Aviv). In addition the contractor should specify maximum time needed for delivery of items to be repaired. 15. Maintenance Without prejudice to the warranty obligation above, the Contractor shall also provide on-site maintenance services for the proper functioning of the System. The Contract price includes full maintenance services for one year during the warranty period. Full maintenance services shall include: - preventative maintenance - on-call interventions - any software update/upgrade for the System that will be become available - all necessary replacement and spare parts, if not covered under warranty As part of the On-Site acceptance, the Contractor shall provide to the local engineer and to the SSDL physicist a plan for preventative maintenance and the name and contacts of a service representative/office for on-call maintenance intervention. Extension of maintenance: Following the initial one-year full warranty including parts and labour, the Contractor shall provide a quotation for the continuation of maintenance services on an annual or biannual basis for 5 additional years. The applicable financial conditions shall be quoted separately. Page 7

8 APPENDIX 1 Layout of the calibration premises at the SSDL of Israel. The irradiation room marked as Co-60 is dedicated for a Co-60 therapy level calibration system Page 8