Modern irradiators release product based on two criteria: monitored critical processing parameters (CPP’s) and verification from reference dosimetry. Both criteria must be satisfied for an acceptable treatment.

For a large batch of products, there are typically a small handful of dosimetric measurements made for the purposes of routine processing. During this time and for the same reason, the irradiator is taking thousands of measurements of critical operating parameters. Proponents of parametric release will emphasize the sheer amount of machine data being collected. This is an important aspect but an incomplete picture. The value of the test result can only be as good as the test itself: the analysis performed on the data being collected is key to unlocking the potential of this technology.

Criteria of the past such as configurable allowed tolerances (e.g. +/- 5%) were improved upon dramatically by Josef Mittendorfer’s “Process Value” and Mevex’s Dose Variation Factor. These systems calculate a single compound factor from monitored CPP’s to represent dose delivery. While this was a significant improvement over its predecessors, its simplified approach loses a lot of detail in its compression.

The Dose Monitor is the next generation of machine-based parameter analysis. Instead of calculating a single factor, it runs a live simulation to build the dose profile being delivered to a product’s surface. The resulting dose profile determines the acceptability of the treatment.

While this tool is currently used in conjunction with physical dosimeters in routine processing, it represents an important step towards the future state of parametric release.