Your radiology Mac was working fine. You open OsiriX MD or Horos to review a stack of DICOM images from a CT scan — and within seconds of loading the series, the application quits. No warning, no error dialog. Console shows a crash report with GPU-related strings you have never seen before. The culprit is almost always a Metal API incompatibility introduced in macOS Sequoia 15.x, and it is fixable without touching the hardware.
Why DICOM viewers crash on macOS Sequoia 15.x
DICOM viewers like OsiriX MD (by Pixmeo) and Horos (open-source, community maintained) render medical imaging data — CT slices, MRI volumes, PET scans — using 3D graphics APIs. Older versions of both applications used OpenGL, the graphics standard Apple deprecated in macOS Mojave (2018) and removed the dedicated driver for in macOS Ventura. Sequoia 15.x tightened GPU memory allocation for non-App-Store applications further and completed the Metal-only graphics pipeline. When these older apps try to allocate a large GPU memory buffer for volume rendering of a 1,000-slice CT scan, the call fails silently and the application crashes.
The second cause specific to Apple Silicon Macs (M1, M2, M3, M4) running Intel-only builds under Rosetta 2 translation: the translation layer adds latency to GPU memory allocation calls that Sequoia 15.x now enforces with a tighter timeout. The result is a crash that appears hardware-related but is entirely software-driven.
How to diagnose the exact crash cause
Step 1: Check the crash log in Console
Open Console (Applications → Utilities → Console), click Crash Reports in the sidebar, and find the most recent OsiriX or Horos crash entry. Look for these strings in the first 30 lines of the report:
MTLCommandBufferorAGXFirmwareKA— Metal GPU command buffer fault. The app is using an outdated rendering path.OpenGLin the stack trace — confirms the app is still using the legacy pipeline. Update immediately.IOGPUDeviceUserClientorIOGPU command timeout— GPU hardware context reset. Could be thermal (dust) or a hardware fault.EXC_BAD_ACCESS (SIGSEGV)with no GPU strings — memory fault unrelated to the GPU. Check RAM with Apple Diagnostics.
Step 2: Check which architecture the app is running as
Open Activity Monitor (Applications → Utilities → Activity Monitor) while OsiriX or Horos is open. Look at the Architecture column next to the app name. If it shows "Intel" on an Apple Silicon Mac, the app is running under Rosetta 2 translation — which is more crash-prone on Sequoia. You need the Apple Silicon (ARM64) native build.
Fix path for OsiriX MD crashes on Sequoia
Update OsiriX MD to version 13.5 or later
Open the Mac App Store and check for OsiriX MD updates. Version 13.5, released in mid-2025, introduced a full Metal rendering pipeline for volume rendering of CT and MRI datasets. If you purchased OsiriX MD outside the App Store (direct from Pixmeo), download the latest build from pixmeo.com — the direct-download build is typically one minor version ahead of the App Store build due to App Store review lag.
After updating, open OsiriX MD and load the problematic DICOM series. If it loads without crashing, the fix is confirmed. If it still crashes, proceed to the safe mode check below.
Boot in safe mode to isolate third-party conflicts
PACS (Picture Archiving and Communication System) client software — such as Synapse, Sectra, or Agfa IMPAX agents — often installs kernel extensions or network daemons that can interfere with GPU memory allocation on Sequoia. On M-series Macs, shut down completely, hold the power button until "Loading startup options" appears, select your startup disk while holding Shift, then click Continue in Safe Mode. Open OsiriX MD in safe mode and try loading the same DICOM series. If it works in safe mode but crashes in normal mode, the conflict is with a background PACS agent or VPN — identify and update it.
Fix path for Horos crashes on Sequoia
Back up the Horos database first
Before touching anything, open Finder and navigate to ~/Documents/. You should see a folder called "Horos Data" — this is your entire DICOM database. Copy this folder to an external drive or another location. This takes a few minutes for large databases but is critical. The Horos app itself can be reinstalled freely; your patient data cannot be reconstructed if it is lost.
Update to Horos 4.0 or later
Download the latest Horos release from horosproject.org. Horos 4.0 was rebuilt with a native Metal rendering path and universal binary support for Apple Silicon. Drag the new Horos app to your Applications folder, replacing the old version when prompted. Launch Horos — it will detect the existing Horos Data folder and migrate your database automatically. This migration takes 2–10 minutes depending on database size. Do not quit during migration.
If Horos still crashes after updating
Check Console for the crash log. If you see CoreData errors, your DICOM database index file may be corrupted. Open Horos, go to File → Database → Rebuild Thumbnails and Previews, then File → Database → Check and Repair Database. This process runs silently for large databases — give it 20–30 minutes. For databases above 500 GB, this step is often necessary after any major macOS update because Sequoia updates the SQLite version and the old index format needs rebuilding.
India-specific context: clinic environments and Mac hardware
Radiology workstations in Indian clinics, hospitals, and diagnostic centres face a specific hardware challenge: high ambient temperatures (especially during summer, when AC may be intermittent), dust from construction near clinics, and power fluctuations. MacBook Pros and iMacs used as DICOM workstations in these environments accumulate dust in vents faster than in an air-conditioned office environment in a cooler climate.
Dust-blocked vents cause the GPU to throttle aggressively under the heavy rendering load of a large CT volume. On Sequoia 15.x, aggressive thermal throttling can cause GPU command buffer timeouts — which look identical to a software crash in Console. If OsiriX or Horos is updated and still crashes during heavy rendering, clean the vents. Our internal cleaning service covers thermal paste and vent clearing for MacBook Pro and iMac models used in clinical settings.
Power fluctuations — common during monsoon season in many Indian cities — can cause filesystem corruption that manifests as Horos database errors. An UPS (Uninterruptible Power Supply) with AVR (Automatic Voltage Regulation — a circuit that keeps voltage stable even when input fluctuates) is strongly recommended for any radiology workstation in India. If you suspect monsoon-season corruption, run First Aid on your startup volume from macOS Recovery before attempting a Horos database repair.
When to bring the Mac for hardware diagnosis
If OsiriX MD or Horos crashes after updating to the latest Metal-native version, runs stably in safe mode, has no PACS agent conflicts, and the vents are clean — but crashes consistently during volume rendering of large datasets — a hardware GPU fault is possible. On Intel MacBook Pros from 2016–2019, AMD GPU failures are a known failure mode. On M-series Macs, GPU faults are rare but do occur after physical shock or severe thermal events.
Diagnosis cost: ₹149 at your door. If a hardware fault is confirmed, we provide a written assessment you can share with your IT procurement team or insurance provider. See the Apple MacBook service page for model-specific repair details, or motherboard and chip-level repair for Intel MacBook Pro GPU faults.
Typical hardware repair costs in India
Intel MacBook Pro AMD GPU repair (reflow or chip replacement): ₹8,000–₹18,000 depending on model. Fan replacement to resolve thermal throttling: ₹2,500–₹4,000. Thermal paste replacement for Intel MacBook Pro: ₹1,500–₹3,000. M-series Mac cooling service: ₹2,000–₹4,500.
A note from the LRW Engineer Team
We have handled several DICOM workstation Macs from clinics in Hyderabad where the crash was traced back to a Horos database running on a 2018 MacBook Pro with a dust-blocked fan and thermal paste that had not been replaced in five years. After a clean and thermal paste service, Horos 4.0 ran without a single crash. The combination of software update and hardware maintenance resolves the vast majority of DICOM viewer crashes we see on Sequoia. WhatsApp us at 7702503336 if you need a same-day doorstep diagnosis for your radiology workstation.