Molybdenum Sinter-Cladding of Solid Radioisotope Targets

Round  1

Reviewer 1 Report

General comments:

The manuscript reports, although in a concise way which better resembles a short communication, the description of an additional, alternative, technical way about solid targets manufacturing, for high-current cyclotron-Tc99m production. The approach is based on the deposition of a given layer thickness of 100Mo-enriched metal slurry material deposited on a backing plate (different metals but mainly made of copper). The final adhesion is then obtained by a high-temperature bonding processes in oven, under hydrogen atmosphere. Such a study is not new, but its refinement to the scope may be considered as one of the different target production technology approaches, underway in the last ~10 yrs, which is part of the international effort aiming at developing an easy, cost-effective and fast, solid targets construction for the alternative Tc99m radioisotope production route. This approach is an additional one with respect to that others based on the electroplating as well as other technique already developed, which have moreover been published. For some metals, however (like precisely Molybdenum) the electroplating process is known to be unsuited. 

I have read the manuscript and found it clear. Although some aspects would certainly have been more interesting if they had been reported in a more in-depth way, (e.g. a more detailed description some step process reported and highlighted in the manuscript text), as "short communication”, I found it well balanced. However, in some parts in the body text some clarification are warmly requested. 

Specific comments

Some (minor) revisions are needed prior the manuscript may be accepted for publication. The revisions suggested, as well as specific comments, are reported directly on the Pdf file of the manuscript attached, using the commenting tools. They have to be considered by the authors as a reference for requested revision in manuscript drafting. Authors are asked to improve the manuscript in the highlighted parts and to meet the revisions requested or to make, in addition, their own modifications.

Comments for author File: Comments.pdf

Author Response

Reviewer 1 comments

General comments:

The manuscript reports, although in a concise way which better resembles a short communication, the description of an additional, alternative, technical way about solid targets manufacturing, for high-current cyclotron-Tc99m production. The approach is based on the deposition of a given layer thickness of 100Mo-enriched metal slurry material deposited on a backing plate (different metals but mainly made of copper). The final adhesion is then obtained by a high-temperature bonding processes in oven, under hydrogen atmosphere. Such a study is not new, but its refinement to the scope may be considered as one of the different target production technology approaches, underway in the last ~10 yrs, which is part of the international effort aiming at developing an easy, cost-effective and fast, solid targets construction for the alternative Tc99m radioisotope production route. This approach is an additional one with respect to that others based on the electroplating as well as other technique already developed, which have moreover been published. For some metals, however (like precisely Molybdenum) the electroplating process is known to be unsuited. 

I have read the manuscript and found it clear. Although some aspects would certainly have been more interesting if they had been reported in a more in-depth way, (e.g. a more detailed description some step process reported and highlighted in the manuscript text), as "short communication”, I found it well balanced. However, in some parts in the body text some clarification are warmly requested. 

 The authors thank the referee.  We have included the suggested changes in the edited document and commented on the recommendations included in your  .pdf  appendix.  Hopefully this communication will serve to provide a simple and cost effective target preparation technique for regularTc99m production.

Specific comments

Some (minor) revisions are needed prior the manuscript may be accepted for publication. The revisions suggested, as well as specific comments, are reported directly on the Pdf file of the manuscript attached, using the commenting tools. They have to be considered by the authors as a reference for requested revision in manuscript drafting. Authors are asked to improve the manuscript in the highlighted parts and to meet the revisions requested or to make, in addition, their own modifications.

peer-review-3630285.v2.pdf

Author Response File: Author Response.pdf

Reviewer 2 Report

The submitted manuscript is an interesting account of a partially developed technique for the preparation of molybdenum accelerator targets which may have relevance to the accelerator production of technetium-99m. The process is simple, fast, likely relatively low cost, and may be applicable to other metals target materials for the production of different radionuclides. However, its development is unfinished -- several of the targets described failed the adhesion tests. These tests did not include actual irradiations, radiochemical processing, or usual radiochemical assays of the produced Tc-99m's radiochemical quality. Since there are already multiple reports of isotopically enriched Mo targets prepared by hydrogen-assisted reduction in different environments that tolerate beam intensities >300 µA, I recommend this work be resubmitted following complete characterization and recycling of the target materials as described in the final sentence of the Discussion section.

Author Response

 would not like to sign my review report
( ) I would like to sign my review report

English language and style

( ) Extensive editing of English language and style required
( ) Moderate English changes required
(x) English language and style are fine/minor spell check required
( ) I don't feel qualified to judge about the English language and style

Comments and Suggestions for Authors

The submitted manuscript is an interesting account of a partially developed technique for the preparation of molybdenum accelerator targets which may have relevance to the accelerator production of technetium-99m. The process is simple, fast, likely relatively low cost, and may be applicable to other metals target materials for the production of different radionuclides. However, its development is unfinished -- several of the targets described failed the adhesion tests. These tests did not include actual irradiations, radiochemical processing, or usual radiochemical assays of the produced Tc-99m's radiochemical quality. Since there are already multiple reports of isotopically enriched Mo targets prepared by hydrogen-assisted reduction in different environments that tolerate beam intensities >300 µA, I recommend this work be resubmitted following complete characterization and recycling of the target materials as described in the final sentence of the Discussion section.

The authors thank the referee for the comments.  The intent of the poster and this manuscript was to report a simple and effective coating technique with step by step instructions to the WTTC community.  The authors emphasize the simplicity , time and cost  considerations of the target preparation for cyclotron production of Tc99m so very important for routine commercial production.  This is a short communication that we believe is timely and relevant.  The manuscript has been modified to reflect the referee’s comments.  Thank you again.

Submission Date

28 December 2018