Developing Real-Time Measurements for Radiation Technologies with LabVIEW and PXI Platform

Author(s):
Sergey Korenev - STERIS Corporation
Leon Grossman - Dynamic Motion Control Inc.
Stanislav Rumega - Dynamic Motion Control Inc.
Ivan Korenev - STERIS Corporation

Industry:
Research

Products:
PXI/CompactPCI, LabVIEW

The Challenge:
Implementing a more reliable and flexible system for measuring electron beam doses absorbed in product to replace the standard, limited system of measurement.

The Solution:
Creating a highly accurate and efficient real-time measurement system using NI PXI-1025 MegaPAC and LabVIEW.

Monitoring and Testing Radiation
Radiation electron beam technologies have many industrial applications in sterilization, food irradiation, curing of polymers, degradation of polytetrafluoroethylene (PTEF), destruction of toxic gases, and as components of electric power stations. A radiation facility consists of an electron accelerator with a radiation safety shield, conveyor system for delivery of products to the area of treatment and a system for monitoring absorbed doses in the product. This system of monitoring and testing the absorbed doses in materials is an important component of any radiation facility. The efficiency of this product irradiation process depends directly on the abilities and precision of the measurement system.

Currently, operators apply routine film dosimetry as the standard method of measuring absorbed radiation dose. In film dosimetry, radiochromatic film is exposed during the irradiation process, and then later developed and analyzed. This process has major limitations with respect to the types of electron accelerators it operates with and the levels of absorbed doses it can measure. Designing a real-time system with film dosimetry is physically impossible, because the user must first expose the film to radiation, and then develop it to finally obtain the radiation measurements.

Creating an Adjustable and Efficient System with LabVIEW
Using the physical properties of electron beams, STERIS Corporation patented a method for real-time measurements of absorbed doses in a production environment. By combining the NI PXI-1025 MegaPAC with absorbed energy sensors, we form the foundation of the new measurement system. These components make the system versatile and applicable with all types of electron accelerators.

The real-time monitoring system includes absorbed beam energy sensors positioned after the irradiated product on the beam path in the area of treatment. We based the measurement instrumentation electronics in the system on a NI PXI-1025 MegaPAC chassis, which includes a PC, switch and oscilloscope modules. The signals from the sensors arrive to the two switch modules and the oscilloscope card eventually registers these. We developed a special algorithm, STERIS Doses On-Line, using LabVIEW to perform the processing of the data from the sensors.

With the system, the operator easily can adjust the parameters of electron beam, sensors, conveyer, and the product on the LabVIEW setup screen. The screen displays current beam signals from sensors and calculated absorbed doses. The program performs two types of dose measurements– current dose for product moving on the conveyor and accumulated dose when the conveyor stops. This system also performs three modes of operations with data from sensors and electron beam parameters, including the real-time monitoring of absorbed doses, calibration of primary kinetic energy of the electron beam, and calibration of sensors with an external pulse generator.

The system’s features include the ability to log measurement results to a file and print a protocol of the measured absorbed doses. These logs include the main information about the beam and product parameters. The system simplifies evaluation and control of absorbed doses in products in accordance with government and FDA regulations and customer requirements.

By choosing LabVIEW as the development tool for the application, we easily implemented a rather complex program architecture. With the multithreading and synchronization tools in LabVIEW, we created the software as a collection of components with a uniform structure that serve multiple purposes. Different components, including user interface, test logic, and a device server, handle specific areas of the application on various levels– user interface, test logic, and device server. These components run simultaneously, asynchronously, and independently of each other, while collaborating and exchanging data through queued messages of a standard structure.

Realizing New Possibilities in Radiation Industries
There are multiple benefits to this new real-time measurement. This is a revolutionary technique for monitoring absorbed doses in radiation technologies, especially when compared to routine film dosimetry. It tremendously decreases the time necessary for evaluation and calibration of absorbed doses, while greatly increasing the efficiency of radiation technologies. The system built on National Instruments products is more reliable, flexible, and simple than traditional methods of radiation measurement. It constitutes a new step in the advancement of the radiation industry.

For more information, contact:
Dr. Sergey Korenev
Steris Corporation
2500 Commerce Drive
Libertyville, IL 60048
Tel: 847-573-3223
Fax: 847-247-0882
E-Mail: sergey_korenev@steris.com

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