Introduction
The expansion of our PET isotope production with a new TR-19 cyclotron necessitated a suitable solid target transport system. None of the known existing and proposed solid target transport systems (STTS) was able to meet the technical and budget requirements of the MIR cyclotron facility [5].
A unique carrier design allowed us to develop a fully automated 50.8 mm inner diameter pneumatic tube STTS with an in-hot-cell compact form factor receiving station. The cyclotron or vault side loading station is a mere vertically symmetric version of the in-hot-cell station. The carrier is able to accommodate any of our inhouse developed 86Y, 64Cu, 76Br, 89Zr and 99mTc target holders without further modifications.
Material and Methods
Technical constraints were imposed by the dimensions of the target holders (FIG. 1) and the overall station size (FIG. 3). A receiving station would be inside a hot cell and, up to three sending stations would be located in the confined vault space under the solid target irradiation units. In addition, safety and budget requirements demanded a fully automated, easy to maintain STTS.
The target holders are of various geometries with the 99mTc having the maximum dimension of 46.65 mm along its diagonal.
Pseudo carriers with diameters ranging from 41 to 49.5 mm (no wear band) and lengths from 50.8 to 102 mm were tested on 50.8 mm inner diameter Kuriyama Tigerflex™ and Goodyear Nutriflex™ tubing. Smaller diameter and length test samples became wobbly, slow, and were getting stuck on occasion. Lengths in the upper limits became stuck in turns with radii close to the minimum radius of the tubing. The necessary negative pressure was achieved by employing a 2.5pHP Ridgid WD06250 blower. The transparent Goodyear Nutriflex™ tubing was chosen for the further STTS development.
A carrier capable of loading and unloading regardless of its axial orientation was constructed.
This novel design allows for a relatively compact station W 112 × H 220 × L 300, which reduce the dependence on the location of the tube openings in the walls of the hot cell (BqSv, Taiwan). As a result the station can be conveniently placed in areas not typically occupied by processing modules or used by chemists, e.g. close to the upper left corner. To avoid reliance on expensive proprietary parts, all components were designed or chosen to insure reliability with minimal maintenance. The enclosure and opening mechanism are 3D-printable using ABS plastic, and can be made in-house on demand. “Platform sharing” between hot cell and vault stations further simplifies support and maintenance.
As with the mechanical hardware, the electronic components and boards were selected to minimize the dependency on a single supplier. The main controller board is based on Atmel\'s AVR series of microcontrollers, which are known to be largely backward compatible, well documented and have an extensive user support base. A single “brick” controls up to three stations. Bricks can be daisy chained with one functioning as a master.
The control software takes advantage of the rapid development capabilities of National Instrument\'s LabView graphical language. It is intended to work on Unix-like and Windows operating systems as well as to allow control from hand-held devices. Password security, interlocks and traceability follow the accepted safety standards for radioisotope handling.
Results and Conclusion
The Symmetric STTS has proven characteristics of reliability, ease of use and safety over hundreds of runs. Given that no convenient carting path exists, it is the ideal means for bringing solid target holders from the underground cyclotron vault to the chemistry processing hot cells at ground level. Transported activities are less than 37.0 GBq (1.0 Ci) for 64Cu and 3.7 GBq (100 mCi) for 89Zr. Carrier velocity is about 4.7m/s minimizing the time activity is present between cyclotron and hot cell. No human interaction with the irradiated target is needed during transport. The carrier does not need to be taken out of the STTS. Even though the BqSv hot cells are equipped with teletongs, they are not needed to recover the target when it arrives at the hot cell; the target is directly dropped into the processing module, e.g. the dissolution vessel for 64Cu processing.
The software is engineered in a manner that gives the operator full control of the states of the sending and receiving stations. At the same time, it avoids graphically dense and overloaded GUI in order to reduce the probability of human error. Currently the control program runs on a PC/Laptop and communicates with the controller over USB. LabView provides add-ons that allow control with a tablet or other hand-held (under development).
The fully automated symmetric STTS is ideal for isotope production facilities that are being envisioned, conceptualized or are in their planning stage. Its versatility, low initial and operating costs might even justify deployment in facilities which already employ a less optimal solid target transport.
Invention application for the Symmetric STTS was filed with the Office of Technology Management of Washington University in Saint Louis, Missouri, USA.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa.de:bsz:d120-qucosa-166269 |
| Date | 19 May 2015 |
| Creators | Tomov, D., Lawrence, L., Gaehle, G. |
| Contributors | Mallinckrodt Institute of Radiology (MIR), Washington University in Saint Louis, Missouri, USA,, Helmholtz-Zentrum Dresden - Rossendorf, |
| Publisher | Helmholtz-Zentrum Dresden - Rossendorf |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:conferenceObject |
| Format | application/pdf |
| Source | WTTC15 |
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