Milestone-Proposal talk:Active shielding of superconducting magnets

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Citation -- JaninA (talk) 20:14, 8 September 2018 (UTC)

Dear Proposer,

may I suggest that you have a look at the citation in the nomination. The second sentence is too long and not grammatical...

Also there is no information which IEEE Unit will pay for the plague.

Kind regards


Re: Citation -- Rmuttram (talk) 23:20, 12 September 2018 (UTC)

The second sentence has been re-written. Hopefully it now reads better, although it is only one word shorter.

Dear Proposer -- JaninA (talk) 21:10, 8 September 2018 (UTC)

please find my further notes and comments in respect to the Milestone. I hope they will be of some help.

Kind regards


Notes: '1. Why different dates in the Proposal?' Year or range of years in which the achievement occurred: 1961 to 1989 Title of the proposed milestone: The active shielding of Superconducting MRI Magnets (1984-87) Plaque citation summarizing the achievement and its significance: At this site between 1986 and 1987......

We therefore proposing that this milestone be focused on the third major element that has enabled the widespread and flexible adoption of these machines - Active Shielding which was developed at the Eynsham site with the first actively shielded magnet completed in 1986 leading to the first MRI machine deployment at 1.5 Tesla in 1989.

2. How the public can access the site is missing?' How is the site protected/secured, and in what ways is it accessible to the public? The site is a significant design and manufacturing location and is staffed on a 24/7 basis throughout the year.

3. Why differences in the name? Who is the present owner of the site(s)? Siemens Magnet Technology Ltd., part of Siemens Healthcare

and Siemens Magnet Systems have recently developed a 7T magnet which was runner up for the prestigious UK Royal Academy of Engineering MacRobert Award in 2016.

4. Only l/5 of the text for the section titled What is the historical significance of the work (its technological, scientific, or social importance)? is devoted to the topic of the proposed Milestone. The rest is devoted to the principle of the MRI itself… Also the part dealing with a building where early work was conducted (in a different location) is a bit confusing. Once could think it refers to the building where the plague is to be.

Re: Dear Proposer -- Rmuttram (talk) 23:42, 12 September 2018 (UTC)

1. I hope I have clarified this now: The first prototype was built in 1986, the first (1.5T) MRI machine delivered in 1989.
 2. Section expanded.
 3. Added some text to clarify: the company is, as you say, currently called Siemens Magnet Technology which is part of Siemens Healthcare  (now known as Siemens 'Healthineers'). At the time of the development it was called Oxford Magnet Technology.
 4. I have added some more text on the Active shielding element but we feel it is essential to put this enabling technology in context. The plaque location is clearly stated to be the current (Eynsham) site which has been the home of Oxford Magnet Technology and now Siemens Magnet Technology since 1984

Re: Dear Proposer -- Rmuttram (talk) 10:29, 7 March 2019 (UTC)

The proposal has been restructured and additional information added. The text detailing MRI has been replaced by a link. Further information on the significance of Active Shielding in the timeline of MRI developments has been added including a file from Siemens Magnet systems showing growth in delivered volumes.

Suggestions for editing the citation -- Administrator4 (talk) 15:09, 30 October 2018 (UTC)

I recommend shortening the citation by deleting the corporate names and focusing on the achievement, thus:

At this site, between 1986 and 1989, the first actively shielded superconducting magnets suitable for practical Magnetic Resonance Imaging (MRI) use were engineered, designed and produced. Active shielding reduced the size, weight, and cost of MRI systems, and allowed machines to be more easily transported and flexibly located benefiting advanced medical diagnosis all over the world.

Re: Suggestions for editing the citation -- Rmuttram (talk) 10:38, 7 March 2019 (UTC)

Your suggestion has been accepted with a couple of other minor edits

- 2nd July 2019 citation update following dialogue with Robert Colburn - 'engineered' changed to 'conceived' to avoid overlap between 'engineered' and 'designed'.

-- JaninA (talk) 18:17, 9 March 2019 (UTC)

I approve the Nomination for consideration by the History Committee.

Expert Opinion -- JaninA (talk) 13:39, 10 March 2019 (UTC)

From: "Wu, Anbo AB (GE Global Research, US)" <> Date: Thursday, 17 January 2019 at 22:55 To: "Mazierska, Janina" <> Subject: RE: assessment of an IEEE Milestone nomination 2018-04 “The active shielding of Superconducting MRI Magnets (1986-89)”,

Dear Prof. Mazierska,

I couldn’t log onto the IEEE-milestone website. Please see my input below.

To my best knowledge, the Oxford Magnet Technology Ltd developed the first actively-shielded superconducting MRI magnet in 1986. It is a milestone for MRI industry. To make the history clear, I would suggest to grant the milestone to Oxford Magnet Technology(OMT) and describe its relation to Siemens Magnet Technology(SMT), instead of simply granting to SMT.

As a side note for your information, actually the GE Research Center developed the first 1.5T full-body MRI system and acquired the first MRI image in 1.5T highest field in 1983. The successful results translated into the highly successful 1.5 T MRI product-line. The passively-shielded magnet used in the first 1.5T MRI system was ordered from Oxford Instrument.

Kind regards, Anbo

Expert Review -- Jason.k.hui (talk) 22:50, 28 June 2019 (UTC)

The following is an expert review from Dr. Michael Parizh, Principal Scientist at General Electric - Global Research in Niskayuna, NY received on 28 June 2019:

Dear Dr. Hui –

I fully support the proposed IEEE Milestone “Active shielding of superconducting magnets” at the Siemens Magnet Technology site (formerly Oxford Magnet Technology, Eynsham, Oxfordshire, UK).

Answers to your questions:

1. Is the suggested wording of the plaque citation accurate?


2. Is the evidence presented in the proposal of sufficient substance and accuracy to support the citation?

Yes, the evidence is sufficient. In short, the actively-shielded MRI scanners ensured commercial attractiveness of the MRI scanners by dramatically reducing the footprint required for the scanner installation and reducing the scanner price. Since early 1990s, practically all commercial superconducting MRI scanners (over 50,000 units were produced over years), and some NMR systems are actively shielded. The achievement was introduced in a well-known IEEE Trans. Magn. Paper IEEE TRANSACTIONS ON MAGNETICS, VOL. MAG-23, NO. 2, MARCH 1987; CONSIDERATIONS IN THE DESIGN OF MRI MAGNETS WITH REDUCED STRAY FIELDS by D.C. Hawksworth, I.L. McDougall, J.M. Bird and D. Black.

3. Does the proposed milestone represent a significant technical achievement?

Yes, the actively-shielded magnets represent a significant technical achievement. Active shielding, a great, non-obvious innovation, changed configuration of the MRI scanners. Magnet designers needed to address multiple challenges including but not limited to force/stress constraints, quench protection, high peak magnetic field, interaction with other MRI scanner components, keep a compact magnet size, develop reliable, cost-efficient cryogenic approaches.

Approval -- JaninA (talk) 09:05, 29 June 2019 (UTC)

So now we have two positive expert opinions on this nomination as required by our procedures. Hence, I give my approval as an Advocate for this Milestone

Re: Approval -- Jason.k.hui (talk) 15:45, 2 July 2019 (UTC)

I have reviewed the milestone proposal and am in favor in having it moved forward for History Committee consideration.

Jason Hui IEEE History Committee Vice Chair Milestones Subcommittee Chair

Additional Expert Review -- Jason.k.hui (talk) 18:00, 21 July 2019 (UTC)

The following is a review of the milestone proposal conducted by Dr. Kathleen Amm, Magnet Division Director at BNL, received on 17 July 2019:

Dear Dr Hui,

Please find below my answers to your questions:

1) Is the suggested wording of the plaque citation accurate?


2) Is the evidence presented in the proposal of sufficient substance and accuracy to support the citation?

Yes, both the paper and patent demonstrate that OMT was the first to demonstrate this technology, a critical technology that enabled the expansion of the MRI market.

3) Does the proposed milestone represent a significant technical achievement?

Absolutely. Without this invention, MRI magnets were incredibly difficult to site due to weight limitations and also stray field. This has allowed MRI to be able to be installed in many hospitals around the world, and allowed MRI suites to be cost effective in terms of siting the magnets. In addition, the image quality and performance of these systems have been greatly enhanced.



Another Expert Review -- Jason.k.hui (talk) 14:16, 3 August 2019 (UTC)

The following is an expert review from Dr. Mark Bird, Director of MS&T at NHMFL-FSU received on 30-31 July 2019:

Dear Jason,

Yes, development of actively shielded MRI magnets was a major milestone in MRI technology that had an important impact on clinical diagnostics, etc. It is probably worthy of a plaque.

I’m not yet sure if Siemens was first. I’m still looking into this. It appears you do not have a reviewer from IGC, one of Siemens/Oxford main competitors at that time.

However, the claims are a little overstated. It should probably be pointed out that there are two basic types of MRI: clinical (used in patient diagnosis) and research (used to develop a better understanding of the body, organs, etc.). The proposal claims:

“1.5 and 3 Tesla magnets are now common and Siemens Magnet Systems have recently developed a 7T magnet which was runner up for the prestigious UK Royal Academy of Engineering MacRobert Award in 2016. A magnet of that size would be virtually impossible to realise without active shielding for the reasons set out in the section below.”

It is simply not true that active shielding is required for 7 T MRI. There were ~forty 7 T human MRI magnets built by Magnex (originally a stand-alone company, then part of Varian, then part of Agilent). I know that many of them had passive (iron) shielding. I thought all of them did. They were all used as research magnets. Magnex also built 9.4 T and 10.5 T human MRI magnets with passive shields. It might be that active shielding is essential for the number of sales to rise to the level that Siemens is interested in. The text should be re-written.

Dear Jason,

Attached is a photograph of one of Intermagnetics General Corporation’s marketing documents. It indicates they completed shielded MRI magnets in the 1986-1988 timeframe. This is the same or slightly earlier than the Siemens claim. In fact the document states “World’s first ‘actively’ shielded . . .”.

I expect that you are aware that many innovations are not patented. Rather they are kept as trade secrets. If one files a patent one is required to explain the idea which allows competitors to copy it easily, although illegally. The patent holder must then sue to prevent a competitor from using the technology. Of course the competitor will frequently claim small changes to the technology to get around the patent. On the other hand, if an innovator does not patent, then it is more difficult for a competitor to copy the technology. Consequently, just because Siemens was granted a patent by the US Patent office does not mean they were first.

As I understand, both companies marketed shielded MRI magnets in the US during the late 1980s and early 1990s. I don’t know if Siemens filed suit against IGC for patent infringement. If not, this suggests that they realized that IGC was actually ahead of them or was using technology sufficiently different from theirs to obviate the patent.

As I described in a previous e-mail, the text is overblown. 7T MRI was built without active shielding as was 9.4 T MRI and 10.5 T MRI.

It appears to me that it would be inappropriate for the committee to grant the award without further clarification of the historical accuracy of who was first. It might be that two plaques would be more appropriate. One in Oxford at Siemens, and one near Schenectady at Phillips (IGC).

In answer to your specific questions:

1) Is the suggested wording of the plaque citation accurate?

MDB: No, it states Siemens/Oxford was first. It appears to me that Phillips/IGC was first or at the same time. This should be clarified before an award is made.

2) Is the evidence presented in the proposal of sufficient substance and accuracy to support the citation?

MDB: No. The only evidence presented that Siemens was first is the US patent. It may well be that IGC had the technology prior to Siemens and did not patent. It appears to me that both companies made and marketed shielded magnets after the patent was awarded which suggests that Siemens was not able to enforce its patent. There needs to be clarification of this prior to making an award. Did both companies market magnets? If so, did Siemens sue for patent violation? If not, why? Again, it might be that 2 plaques would be the appropriate solution, or, perhaps, only one at Phillips/IGC.

3) Does the proposed milestone represent a significant technical achievement?

MDB: Yes, it is a significant technical achievement.

Rod Muttram: I believe the proposal considered as a whole made clear that high-field strength magnets can be realised without active shielding but they are then much more costly at the system level and problematic for hospital or health clinic installation, however I have toned down 'practically impossible' and amended the wording in both relevant sections to make this clearer.

The OMT patent application is dated 7th November 1984 and granted on 6th May 1986. The only evidence presented here of parallel work at IGC is a photograph of a brochure quoting work from 1986 to 1988. Siemens tell me that the extensive history they have of IGC makes no mention of any such work. It seems to me that the expert is taking a very partisan view and his argument regarding patents does not hold water. An equally valid interpretation would be that IGC saw the OMT patent and started work on developing a similar technique based on OMT's improvements over the prior art recognised in the Patent but sufficiently different to get round the patented technique. That would still make OMT/Siemens clearly first. If evidence of concurrent development at IGC can be presented then there would be a case for a second plaque but nothing presented thus far would indicate that is the case and I certainly see nothing that indicates that this milestone should be delayed.

The advocate suggested some changes to the citation, I have changed he first sentence to include 'diagnostic..(MRI)' but have not inserted the word 'patented' as suggested as I feel that is unnecessary, but if the Committee felt that appropriate it would be acceptable.

Rod Muttram (24 August 2019): Date range in Citation and Nomination text (two places) changed to 1984-1989 at Advocate's suggestion to align with the submission dates of the US and European Patents.

Active shielding defined -- Allisonmarsh (talk) 06:18, 13 September 2019 (UTC)

Do we have to explain what active shielding is?

Minor amendment to Citation -- Rmuttram (talk) 17:50, 2 November 2019 (UTC)

The citation as revised at the History Committee meeting was shown to Siemens. They were concerned that the use of the word 'machines'in the the second sentence might imply that the machines by themselves that are lighter. In fact the addition of active shielding will somewhat increase the weight of the machine, it is the system weight that is significantly reduced by the elimination of the heavy external iron shields. I have therefore changed 'machines' to 'them'in the second sentence, thus referring back to 'MRI Systems' which removes this potential issue.