Sunny Sanyal
Analyst · CJS Securities
Thank you, Howard. Good afternoon, everyone, and welcome. I'm pleased to report that our financial results for the second quarter were stronger than our expectations, and revenue exceeded pre-COVID levels. Continued strong global CT tube sales and higher sales of industrial digital detectors drove this growth. Demand for our other medical imaging products related to certain elective medical procedures also increased. Our revenues in the second quarter increased 15% sequentially due to gains in both medical and industrial segments. Revenues increased 3% year-over-year.
Our non-GAAP gross margins increased to 35% due to higher volume and a favorable product mix. Our non-GAAP operating expense declined sequentially and year-over-year, reflecting benefits from previous cost reduction actions. Our non-GAAP operating margin improved to 13% of revenues. As a result, non-GAAP EPS was $0.35 and exceeded the top end of our guidance range.
Next, let me give you some high-level insight into how our different modalities and applications trended during the quarter. Medical segment revenues increased 13% sequentially and 1% year-over-year. Momentum in CT tube sales, which has been building over a number of quarters, remained strong in Q2. Many of these tubes were for new systems, which are also expected to result in future sales of replacement tubes. In our other medical modalities, oncology, mammography and radiography also saw growth while fluoroscopy and dental remained flat. We believe this growth is due to demand that had been deferred over the past year as well as from expansion of health care services in some markets.
Revenues in our industrial segment increased 24% sequentially and 13% year-over-year. In Q2, demand for digital detectors for nondestructive inspection increased across several of our industrial verticals. However, demand for our imaging products for security screening at ports and borders as well as baggage screening at airports continued to lag.
Now I'd like to take a few minutes to highlight the great work we're doing in our X-ray tubes business. In future, I'll highlight other areas of our business in the same way. Demand for new CT systems in China and upgrades of CT systems globally are driving growth in our Tubes business. In China, we believe demand is likely to grow at approximately 10% a year for the next several years due to increased installations at fever clinics and a focus on making rural health systems more self-reliant. Our strategy in China has been to establish relationships with local OEMs. I'm happy to say that of the initial 12 CT projects we have been working on with 8 local OEMS, 9 projects have been brought to market and 3 are still in process. We believe that local Chinese OEMs have made very good progress and currently account for approximately 40% of CT sales in China.
Based on our experience, new OEMs tend to initially focus on gaining market share through launching entry-level systems. This has occurred in China for the CT modality. We are now seeing that the local OEMs are ready to expand into 64, 128 and higher sliced CT system projects in order to provide greater diagnostic imaging capabilities, including systems that are needed for cardiac procedures. These projects are potential future opportunities for us and the relationships that we have built with these OEMs over the past 5 years will play a significant role in our continued success in the China CT market.
As part of our local-for-local strategy, our Wuxi facility continued to scale up loading of X-ray tubes for the China market. By loading tubes, we mean assembling the X-ray tube in our core into locally sourced housings for OEMs' specific customizations and final testing before shipping to our customers. Over the past year, while most of our customers maintained momentum with their current R&D projects, many of them have slowed down their commitments to new R&D projects while they assessed the market situation. During the quarter, we saw an increasing momentum in new product development activity within our customer base across their extra imaging product lines, which we interpret as a reflection of their confidence in the markets that they serve.
Our own R&D activity, on the other hand, did not slow down. Later this fiscal year, we plan to introduce 2 new CT tubes, specifically for high-end 256 and 320-slice CT systems. During the quarter, our software business received FDA 510(k) clearance for an enhanced version of our CT lung screening application, which uses artificial intelligence for automated detection of suspicious nodules. And at the same time, during the past few quarters, we have continued to make progress with our investments in innovation focused on nanotube technology.
Now I'd like to share some additional details about this exciting new technology being developed through our joint venture, VEC Imaging. For simplicity, throughout this nanotube discussion, my use of the word our refers to our joint venture, where we own 50%. First, let me start by outlining the differences between conventional X-ray tubes that use thermionics element technology and our cold cathode nanotube technology. On the left-hand side of the slide, you will see that conventional X-ray tubes require an electric power source to heat up a filament. Operating temperatures can get up to 2,400 degrees Celsius. In addition, the ability to place conventional emission sources close to each other is limited, a term that we call packing density. In contrast, our nanotube technology uses a localized electric field to extract electrons from solid-state emitters. This technology operates at room temperature and has very high switching speeds. Due to its form factor in high packing density, our nanotube technology enables us to design X-ray tubes where many emitters can be sequentially arranged and turned on or off at high speeds. These multi-beam X-ray tubes can offer increased design flexibility to build lighter, mechanically simpler and more compact imaging systems. We believe that our nanotube technology will provide many benefits over conventional X-ray sources. First and foremost, we believe that systems designed using Nanotube based X-ray sources will significantly lower the total cost of ownership for hospitals and imaging centers. For example, in a CT application, a lower TCO could be realized by eliminating the very heavy rotating gantry along with numerous interconnected parts, pieces and components that are needed to support the complex mechanical design. These electromechanical components add cost, complexity and weight, and require significant downtime and expenses to maintain, repair and replace over the life of the system. In contrast, systems designed using our Nanotube technology could have very few, if any, moving parts and would be much simpler in design, have a significantly smaller footprint, and weigh much less. This simplicity is expected to result in lower maintenance costs and significantly reduced system downtime.
In addition, the next-generation systems would be smaller, lighter and portable and could give health care organizations additional flexibility of their care delivery process. We believe the combination of our Nanotube technology and Varex's multi-decade long experience with designing and manufacturing X-ray sources will enable our customers to redefine medical imaging in the coming years.
To give you a status update, our R&D efforts with nanotube technology is progressing well. X-ray sources are characterized by energy, emission and a few other parameters. We have achieved our intended energy output of 40 to 180 kilovolts at different emission levels measured in milliamps. We are now conducting accelerated life testing of different configurations of tubes. While life testing is ongoing, to date we have completed over 1 billion projections per emitter at 160 kilovolts. We believe this is the equivalent of several years of emitter life for a typical CT application. We are encouraged by these results and are continuing to move forward with our product development efforts. With that, let me hand over the call to Sam.