Held at the National Physical Laboratory, Teddington, on 31 January 2003

Attendees:	Mike Woods		NPL (Chairman)
	Michaela Baker		NPL (Secretary)
	Janis Brown		Mount Vernon Hospital
	Richard Gadd		North Staffs Hospital
	Christopher Green		Aberdeen Royal Infirmary
	Tim Hosking		North Middlesex University Hospital
	Andy Irwin		St George's Hospital
	Raj Patel		Gloucester Royal Infirmary
	Emma Pearce		Royal Berkshire Hospital
	Jacqueline Roberts		Leeds General Infirmary
	Jill Segerman		Royal Sussex County Hospital
	Rachel Smith		Royal Brompton Hospital
	Harold Stockdale		Royal Liverpool University Hospitals
	William Thomson		City Hospital NHS Trust, Birmingham
	Jill Tipping		Christie Hospital
	Wendy Waddington		Middlesex Hospital (UCL)
	Farnoosh Zananiri		Bristol General Hospital
	Steven Judge		Group Head/Team Manager, NPL
	Simon Jerome		NPL
	Nigel Watkins		NPL
	Clare Scott		NPL
	Kalyani Chari		NPL
	Jo Townley		NPL

The second meeting of the RCUF was held in the Globe Room, Bushy House at the National Physical Laboratory, with 15 medical physicists present (of the 26 registered, due to adverse weather conditions) and 8 NPL representatives - the complete list of attendees is given in Appendix 1.

The purpose of this meeting was to discuss the progress on the actions agreed at the previous meeting, as well as other new issues of common interest related to calibration and measurement. Appendix 2 contains the Agenda of the meeting.

Introduction session:

The aims and activities of the RCUF were once again discussed, particularly with the new attendees, and agreed by all present. The complete Terms of Reference are now available on the RCUF website.

The chairman’s introduction included a re-run of the “Introduction to NPL and the NMS programme” presentation from the inaugural meeting, which can also be found on the Forum’s website.

Similar to the previous meeting, the participants introduced themselves, outlined potential measurement and calibration problems for the radionuclides used in their departments and suggested topics of particular interest for discussions.

Presentations session:

a) The first presentation , given by Michaela Baker, NPL, focused on NMS/NPL projects supporting the actions from the last meeting. It aimed to keep the members informed on the progress on current NPL projects such as: calibration of the NPL radionuclide calibrator for 10R Schott vials and subsequent calibration services for this particular container; characterisation of Copper filter inserts for ¹²³I measurements and possible calibration factor for the NPL calibrator; performance and accuracy of commercial radionuclide calibrators; NPL calibration services available.

b) Richard Gadd from North Staffordshire Hospital, Stoke-on-Trent, presented the draft of the new Protocol for Establishing and Maintaining the Calibration of Medical Radionuclide Calibrators, and their Quality Control.

The revised document will contain two chapters:

• 1^st chapter, based mainly on the existing document, will focus on theoretical aspects such as definitions, principle of calibration, quality control, calibration tolerances, uncertainties, but structured in a more concise and user-friendly format.
• An additional 2^nd chapter will be included in the new protocol, containing relevant examples of possible sources of errors associated with the use of radionuclide calibrators in hospitals.

It was the draft of the 1^st chapter that was presented and discussed at this meeting.

c) Bill Thomson from Birmingham City Hospital then gave a short talk on ⁹⁰Y measurements using a Copper-glass combination filter. The aim of this research is to expand the use of Cu filter inserts to improve accuracy of activity measurements of other “critical” radionuclides besides ¹²³I. A combined Copper-glass filter seems to have the best stopping power for the ⁹⁰Y low energy Bremsstrahlung, to which Capintec systems are particularly sensitive.

All presentations will be available on the Forum website shortly.

Based on the extended suggestions and comments that followed each presentation as well as those made during the introduction, the Agenda for open discussions was agreed.

Discussion session - topics chosen:

1. Future comparison exercises; suggested radionuclides: ³²P, ⁸⁹Sr, ¹²³I repeat, ¹⁸F
2. Performance of dedicated Beta chambers
3. Accuracy of activity measurements for pure beta emitters: ³²P, ⁸⁹Sr and ⁹⁰Y
4. Assay of ¹³¹I therapy capsules
5. Reference sources (and QA in UK) for short-lived radionuclides: ^99mTc, ¹²³I, ¹⁸F
6. LDR ¹⁹²Ir wires and ¹²⁵I seeds AKR factors for the NPL calibrator and NPL calibration services
7. Further additions to the RCUF website
8. Suppliers/manufacturers attendance at RCUF meetings
9. Commercial NPL-CRC electrometer non-linearity
10. Revised Protocol for Establishing and Maintaining the Calibration of Medical Radionuclide Calibrators, and their Quality Control
11. Database of calibrator types/number used in UK Medical Physics
12. Future meetings

The agreed actions on these topics were:

1.  Future comparison exercises; suggested radionuclides: ³²P, ⁸⁹Sr, repeat ¹²³I, ¹⁸F

It was generally agreed that hospital comparison exercises are very useful and should be continued. ³²P, ⁸⁹Sr pure beta emitters were still the main candidates for the next comparison exercises. For this reason, it was decided to expand the previously proposed ⁸⁹Sr cost-sharing exercise into a UK hospital comparison. This will be run on a similar principle of two NPL-calibrated sources being circulated between hospitals (see minutes from 1^st RCUF meeting on the website) but it will be coordinated by NPL.

This exercise will be advertised in the near future and will be open to all those interested in the activity assay of ⁸⁹Sr.

2. Performance of Beta chambers

This is an outstanding action from the previous meeting – NPL has been in touch with Southern Scientific about specifications/performance of dedicated beta ionisation chambers. Michaela Baker to identify chambers in use (via the form in Appendix 3.) and any problems associated with these systems.

Noteworthy: Recommended factors for pure beta emitters for many commercial radionuclide calibrators are indicative only, and recalibration of these systems is highly recommended - NPL provides calibration services for customer-supplied solution sources of ³²P, ⁸⁹Sr and ⁹⁰Y.

3. Accuracy of activity measurements for pure beta emitters: ³²P, ⁸⁹Sr and ⁹⁰Y

Already discussed in the above actions.

Therapy with pure beta emitting radioisotopes is clearly increasing in the UK and implicitly so is the need to improve the accuracy and traceability of activity measurements for these radioisotopes.

4. Assay of ¹³¹I therapy capsules

Some participants wanted advice on accurate activity assay of ¹³¹I capsules; this issue was addressed by NPL in one of the previous UK hospitals comparison exercises and the “NPL Report CIRM 31” is available to all interested. This also highlighted the need for better advertising of all NPL publications and papers with relevance to nuclear medicine as well as of all calibration services available via the RCUF website.

5. Reference sources (and QA in UK) for short-lived radionuclides: ^99mTc, ¹²³I, ¹⁸F

Following a big growth in PET in recent years, the need to establish a QA system for short-lived radioisotopes in UK is now greater. The brief presentation on the results from the ¹⁸F international comparison exercise was well received, and suggestions were made to either conduct a similar exercise in the UK or for NPL to start supplying ⁶⁸Ge/⁶⁸Ga standard sources. Some interest was also expressed in the final paper of the international exercise, when it becomes available

^99mTc, ¹²³I and other similar short-lived radioisotopes will be addressed at a later stage.

6. LDR ¹⁹²Ir wires and ¹²⁵I seeds AKR factors for the NPL calibrator and NPL calibration services

The ¹²⁵I LDR brachytherapy single seeds and STRANDs calibration factors for the NPL calibrator as well as AKR calibration services using the NPL calibrator are a relatively recent addition and were presented at this meeting. All these factors will be made available to users via the RCUF website.

7. Further additions to the RCUF’s website

• List of NPL papers with medical applications (and links to their pages on the NPL website if possible)
• List of NPL-recommended half-lives for medical radionuclides
• List of all calibration figures for the NPL calibrator and implicitly of all calibration services available
• Users’ feedback option (?!)

8. Suppliers/manufacturers of radionuclide calibrators attendance at RCUF meetings

Once again, all present agreed that representatives from Southern Scientific, Capintec, Amersham, Veenstra, should be invited to future meetings.

Additionally, it was suggested that suppliers of vials and radioactive solutions (i.e.: Amersham, Isotrak QSA, DuPond, Mallinckrodt, etc) should be approached to discuss the importance of reproducible geometry of vials to the traceability and accuracy of activity measurements and therefore to the dose administered to patients.

9. Commercial NPL-CRC electrometer non-linearity

This is an unresolved, long-standing issue, and Mike Woods from NPL presented the results of the linearity tests done at NPL on recent NPL-CRC electrometers, as well as possible adjustment options.

The user community to be kept informed of any further progress on this.

10. Revised QA Protocol for radionuclide calibrators:

Suggestions made:

• Clarify the definitions of “secondary, tertiary and field instruments",
• Replace “check source” terminology with the less ambiguous “consistency source” and to advise how to use this source to check all preset factors of interest,
• Include clear guidance on how to calibrate dose calibrators subsequent to an NPL calibration/ comparison exercise
• Circulate the final draft to all members for comments
• Publish it as a Good Practice Guide (GPG) (and consider whether charges should apply)

11. Database of calibrator types/number used in UK Medical Physics

Michaela Baker to send out a form to all members of RCUF requesting total number of calibrators of specific types within each hospital and to collate these details. This form can be found in Appendix 3.

12. Future meetings

This was the second and final meeting to be organised by NPL as part of the current Oct 2001-Sep 2004, DTI-funded NMS programme. The general consensus was that these meetings, particularly the open discussion sessions, are very beneficial and suggestions to accommodate an additional meeting in the present programme were made. However, programme formulation for the next Oct 2004 to Sep 2007 NMS programme is due to start in the next few months; members will have the opportunity to express any concerns related to the use of radionuclide calibrators and to directly advise NPL on future projects with application in the nuclear medicine field at a Focus Group meeting later this year.

NPL will continue to disseminate future relevant research work via publications, BNMS conferences, RCUF actions and website.

Michaela Baker

2 April 2003