Mastering AVI Implementation via Feasibility Study Test Kits

The transition from Manual Visual Inspection (MVI) to Automated Visual Inspection (AVI) is driven by the need for higher throughput, objective repeatability, and 21 CFR Part 11 compliant data integrity. While MVI relies on the expert judgment of human operators, AVI utilizes high-resolution imaging, rule-based and AI-driven algorithms to ensure 100% inspection of parenteral products. However, the first indication of success of an AVI system is not determined at the point of installation, but during the Feasibility Study. 

By utilizing specialized Test Kits, manufacturers can bridge the gap between human intuition and machine precision, ensuring that the system is set to detect the specific defects of their individual production line.

Before a machine can be engineered, the defects it needs to detect must be rigorously classified. In the world of quality control and lab management, we categorize these risks into three distinct categories:

Critical Defects

These pose a direct risk to patient safety or product sterility. Examples include sidewall cracks, compromised container-closure integrity (CCI), or the presence of extrinsic particulate matter like glass shards or metal.

Major Defects

These do not immediately compromise safety but affect the product's functionality, dosage accuracy, or usability, such as significant under-fills or large intrinsic particles (e.g., stopper fragments).

Minor/Cosmetic Defects

These are typically aesthetic issues that reflect a lowering of perceived quality but do not impact the drug’s efficacy. These include surface scratches, minor label misalignments, or scuffs on the flip-off or metal cap.

Critical and major defects need to be removed reliably with a 100% visual inspection.

To be able to set a benchmark regarding defect detection for AVI machines, the results of manual inspections are required in advance. This is what test kits are for. Test kits can be established for feasibility studies, performance qualification and as functional test kits during operation. We will dig deeper into test kits for feasibility studies in this article. 

The Strategic Role of Feasibility Study Test Kits

A feasibility study is the "proof of concept" phase. Test kits during feasibility studies are used by pharma companies to challenge AVI suppliers during the selection process and compare the results on the same set. The kit serves as a standardized benchmark to evaluate critical performance metrics: the Detection Rate (DR), the False Rejection Rate (FRR) and image quality.

Defect catalogues should always contain:

• All types and sizes of defects typical for the specific manufacturing process, including defect locations on the container (neck, sidewall, bottom, etc…)
• Visualizations of the defects in a defect catalogue including pictures

If available, results of the threshold studies performed with manual visual inspection

Why are these kits the project’s backbone?

Feasibility study test kits directly influence how the system is engineered and built and provide the first indication of its performance.

Optical Setup

Can the cameras see a stainless-steel particle of a certain size through a high-viscosity proteinaceous solution? The kit provides the answer. These tests help machine manufacturers develop the optical setups for different scenarios. 

Establishing the Probability of Detection (PoD)

The kit allows you to find the exact size where a defect becomes "invisible" to the cameras, helping you align the machine’s capabilities with your User Requirement Specification (URS). Pharma manufacturers can also provide defects in the “grey zone” (30% < PoD < 70%) to explore the limitations of the inspection system.

A high-quality feasibility kit is not a random collection of rejects. It is a scientifically curated library:

The Defect Library

It must contain a spectrum of particles (extrinsic and intrinsic) and container flaws (cracks, chips, and seals) and show where these are, e.g. black fibre in liquid.

Product Simulation

To ensure the light refraction and "swirl" patterns are accurate, kits should ideally use the actual product. If this is not possible, a mimicking solution, e.g. placebo with identical viscosity and turbidity is required.

Statistical Balance

Unlike a "Knapp Test" used for qualification (which typically uses a 90/10 ratio of good to bad units), a feasibility kit is often more defect-heavy (around 20% defect samples). However, it is always good to include at least 20–100 "good" units for an early evaluation of the False Rejection Rate.

Precision as a Standard

If you want an AVI system that performs reliably from day one, start with the right feasibility study test kit. It’s the most effective way to turn expectations into measurable results.

If you’d like to discuss how to design or optimize a feasibility kit for your specific product and process, get in touch. We’re happy to exchange insights and support your AVI journey.