Medical-Grade Displays and High Refresh: 60 Hz vs 120 Hz

Clinicians see "120 Hz" and wonder if they are missing out. But upgrading is complex and expensive, potentially offering no real benefit for their specific workflow.

Today, 4K/60 Hz over 12G-SDI + AR glass + templated multi-source covers most intra-op and review needs with plug-and-play stability and >50 m reach.

The choice between a 60 Hz and a 120 Hz medical display¹ is not a simple "more is better" decision. While a higher refresh rate can offer smoother on-screen motion, its real-world benefit depends entirely on the entire imaging chain, from the camera source to the cables and processors in between. For medical environments like the operating room or cath lab, where reliability and consistency are paramount, the theoretical advantages of a higher refresh rate must be carefully weighed against the practical realities of signal integrity², source limitations, and system complexity. This article will break down the key factors to consider, providing a clear framework for evaluating whether a 120 Hz display is a necessary upgrade or an unnecessary complication for a given clinical task.

Perceptual Gap: How Refresh Impacts Seeing & Doing

Fast-moving surgical tools can appear blurry on screen. This motion blur can make precise movements difficult, leading to uncertainty during critical procedures and increased eye fatigue for the surgeon.

120 Hz halves the frame time to 8.3 ms, reducing "sample-and-hold" blur from LCDs. This improves motion clarity and tool tracking, even if the source only provides 60 fps.

A display’s refresh rate, measured in Hertz (Hz), indicates how many times per second the screen can draw a new image. A 60 Hz display updates 60 times per second, while a 120 Hz display updates 120 times. This has a direct impact on the perception of motion. LCD panels, which are used in virtually all modern medical displays, suffer from an artifact known as "sample-and-hold" motion blur. Each frame is held static on screen until the next one is drawn, and our eyes’ continuous motion across this static image creates perceptual blurring. By doubling the refresh rate³ to 120 Hz, the display holds each image for only half as long. This significantly reduces sample-and-hold blur, resulting in smoother, sharper motion. Even if the video source is only 60 frames per second (fps), a 120 Hz display can still improve motion clarity by showing each source frame twice. This creates a more stable image with less perceived judder, which can be beneficial when tracking fast-moving instruments or during rapid camera pans in endoscopy.

Latency Budget: 16.7 ms vs 8.3 ms Frame Time

During a complex procedure, any delay between a surgeon’s action and the visual feedback on screen is problematic. This latency can disrupt hand-eye coordination and reduce surgical confidence.

A 120 Hz display has a frame time of 8.3 ms, half of the 16.7 ms at 60 Hz. This tighter latency budget can reduce the overall glass-to-glass delay in the imaging chain.

Total system latency⁴, or the "glass-to-glass" delay from the camera lens to the surgeon’s eye, is a critical factor in any real-time surgical procedure. This total latency is the sum of delays from every component in the imaging chain: the camera sensor, image processor, cables, and finally, the display itself. The display contributes to latency through both processing time and frame time. Frame time is the minimum time an image must wait before it can be drawn on screen. At 60 Hz, the frame time is 16.7 milliseconds (1 second / 60 frames). At 120 Hz, this is cut in half to just 8.3 ms. By reducing the frame time, a 120 Hz display⁵ tightens the latency budget and can contribute to a lower overall system delay. This provides more immediate visual feedback, improving hand-eye coordination for the surgeon. However, this benefit is only realized if the entire imaging pipeline can support the higher frame rate. If any component in the chain introduces a significant delay, the marginal gain from the display’s faster frame time may be lost.

Source Reality: Baseline fps in Endoscopy/Fluoro/US

Hospitals may invest in 120 Hz displays expecting a major leap in image quality. However, they are often disappointed when the image does not look much smoother than before.

Most medical video sources do not output 120 fps. Fluoroscopy is typically 15–30 fps to manage radiation dose, while endoscopy commonly outputs 1080p60 or 4K60, limiting the benefit of a 120 Hz display.

The benefit of a high-refresh-rate display⁶ is fundamentally limited by the frame rate of the source signal⁷. A 120 Hz display cannot create new temporal information; it can only present the information it receives from the source. In medicine, very few imaging sources actually generate a 120 frames-per-second signal. Electronic fluoroscopy systems, for example, typically operate between 15 and 30 fps. This frame rate represents a crucial trade-off, balancing the need for real-time perception against the clinical imperative to minimize the patient’s radiation dose. Most modern endoscopy camera systems output a signal at 1080p60 or 4K60. While a 120 Hz display can make this 60 fps signal appear more stable by repeating each frame, it is not receiving 120 unique images per second. True 120 fps video pipelines are still uncommon in today’s operating rooms. Therefore, while a 120 Hz monitor might offer some improvement in motion clarity, the full potential of its refresh rate is rarely utilized by the source equipment currently deployed in most hospitals.

Bandwidth & I/O: 12G-SDI, HDMI 2.1, DP 1.4

Upgrading to 120 Hz is not as simple as swapping monitors. The existing cables and infrastructure may not support the massive data bandwidth required, leading to failed installations and costly rework.

12G-SDI, the OR standard for its robustness, tops out at 4K60. Achieving 4K120 requires HDMI 2.1 or DisplayPort 1.4, interfaces that are less common and less reliable for long medical runs.

Delivering a 4K video signal at 120 Hz requires enormous data bandwidth—approximately twice that of a 4K60 signal. This has significant implications for connectivity and infrastructure. In operating rooms and cath labs, the preferred interface is Serial Digital Interface (SDI)⁸ due to its locking connectors, long-distance reliability, and high resistance to interference. The current state-of-the-art, 12G-SDI, can transport a full, uncompressed 4K60 signal over a single cable up to 100 meters. However, it does not have the bandwidth for 4K120. To achieve 4K120⁹, one must use consumer-grade interfaces like HDMI 2.1 or DisplayPort 1.4, often with Display Stream Compression (DSC). These interfaces are not designed for the long cable runs and demanding physical environment of the OR. Their cables are less robust, they lack locking connectors, and they are more susceptible to signal degradation and interference. Attempting to build a 4K120 video chain often means sacrificing the proven reliability of SDI, a trade-off that is unacceptable for mission-critical surgical applications.

Stability & Clarity: Response, MPRT, Glare

A high refresh rate is only one part of motion clarity. A slow pixel response time can negate the benefits of 120 Hz, causing ghosting and smearing that make the image difficult to interpret.

True motion clarity depends on more than just refresh rate. Fast pixel response time (MPRT), low persistence, and effective glare control are equally critical for a sharp, stable image during procedures.

While refresh rate sets the upper limit for motion performance, other factors are equally important in determining the final image clarity. Pixel response time¹⁰—the time it takes for a pixel to change from one color to another—is crucial. If the response time is slow, the benefits of a 120 Hz refresh rate are negated by "ghosting" or smearing artifacts, where a faint trail is visible behind moving objects. A more holistic metric, Motion Picture Response Time (MPRT), measures the total time a pixel is visibly "on" and can better represent perceived motion blur. Beyond display panel technology, physical characteristics are also vital. In the bright environment of an OR, glare from overhead lights can wash out the image and reduce contrast, obscuring important details. Effective glare control¹¹, achieved through anti-reflective coatings and optical bonding, is essential for maintaining image clarity. For many clinical applications, investing in a 60 Hz display with superior response time and glare control will yield better real-world results than a 120 Hz display that neglects these fundamentals.

Standards & QC: DICOM/Color Gamma Consistency

Clinicians need to trust that what they see is accurate. If a display prioritizes refresh rate at the expense of color and grayscale accuracy, its diagnostic and surgical utility is compromised.

For diagnostic reading of static images, GSDF compliance is paramount. In the OR, refresh rate must not come at the cost of stable, calibrated color and consistent luminance.

In medical imaging, consistency and adherence to standards are the bedrock of diagnostic confidence. For radiology reading rooms, where clinicians primarily review static or slow-moving grayscale sequences, refresh rate is a low priority. The most important factors are strict compliance with the DICOM Part 14 Grayscale Standard Display Function (GSDF)¹², stable luminance output, and screen uniformity. These ensure that images are perceived correctly and consistently across different workstations and over time. For surgical applications in the OR, where color video is common, the display must maintain a calibrated gamma curve and consistent color temperature. While a higher refresh rate can improve the viewing experience for motion, it must not be achieved at the expense of these foundational quality standards. Any medical-grade display, whether 60 Hz or 120 Hz, must be built on an architecture that prioritizes stable, repeatable performance. Automated quality control features, such as built-in sensors for luminance and color stability, are far more critical for long-term clinical value than a high refresh rate alone.

Selection & Deployment: End-to-End Readiness

Deciding to upgrade to 120 Hz based on a single specification is a mistake. Without evaluating the entire infrastructure, hospitals risk buying an expensive monitor that provides no tangible benefit.

Build an end-to-end capability matrix. If your sources and backbone are ≤60 fps, prioritize a stable 4K60 system. If your full chain supports 4K120, it can add value for fast-motion tasks.

60fps?”, “Is your cabling HDMI 2.1?”, leading to a recommendation.”>

The choice between 60 Hz and 120 Hz should be a pragmatic, evidence-based decision, not one driven by marketing trends. Before investing in 120 Hz technology, a hospital must perform an end-to-end audit of its imaging chain. This involves creating a capability matrix that answers several key questions. First, what is the maximum frame rate generated by the imaging sources (endoscopes, C-arms, etc.)? Second, does the video-routing infrastructure, including switches, recorders, and extenders, support the required bandwidth for 4K120¹³? Third, is the physical cabling infrastructure based on long-run 12G-SDI or is it prepared for the limitations of HDMI 2.1 or DisplayPort? If the answer to any of these questions indicates a bottleneck at or below 60 fps, then the most sensible choice is to invest in a high-quality, stable 4K60¹⁴ display system. This approach maximizes reliability and value. Only when the entire chain—from source to screen—is confirmed to be 4K120-ready should an upgrade be considered, and even then, only for specific tasks involving fast motion where the benefits are clear.

Conclusion

A reliable 4K60 system via 12G-SDI offers the most practical and robust solution for the vast majority of today’s medical imaging needs, prioritizing stability over theoretical speed. 🚀

👉 To learn more about Reshin medical-grade monitor solutions, contact martin@reshinmonitors.com for customized support.