1. Original Raw Data vs. Reprocessed 0.5mm Slice Data

• Original Raw Data: Unprocessed projection data (sinograms) captured by the CT scanner’s detectors. This is not viewable as images and requires specialized software for reconstruction. It’s stored in proprietary, vendor-specific formats (not DICOM) and is used to generate reconstructed images.
• Reprocessed 0.5mm Slice Data: Reconstructed CT images in DICOM format, viewable with standard DICOM viewers. These high-resolution images (0.5mm slice thickness) are optimized for clinical use, such as diagnosis by radiologists or general practitioners (GPs).
• Key Difference: Raw data is pre-image data requiring reconstruction; 0.5mm slice data is the processed, viewable output. Raw data is not low-resolution images—it’s not images at all until reconstructed.

2. File Size of Original Raw Data

Raw data file sizes vary based on scanner type, scan protocol, detector configuration, and scan coverage. Precise sizes depend on the specific scan but can be estimated:

• Factors:
  • Projections: Thousands per rotation (e.g., 1,000–2,000).
  • Detector Rows/Channels: Multi-detector scanners (e.g., 64–256 slices) generate large datasets.
  • Bit Depth: Typically 16–24 bits per sample.
  • Scan Duration/Coverage: Longer scans increase data volume.
• Estimate: For a typical diagnostic scan, raw data ranges from 500 MB to 5 GB. For a high-resolution, large-coverage scan (like yours with 8 GB DICOM data), raw data is likely 1–4 GB, but could reach 5–10 GB in extreme cases.
• Note: Confirm exact size with the imaging facility, as raw data is proprietary and not standardized.

3. File Size of Reprocessed 0.5mm Slice Data (DICOM)

The DICOM data (approximately 8 GB) represents the reprocessed 0.5mm slice images. This size is reasonable for high-resolution CT scans:

• Calculation:
  • One 512 × 512 pixel slice (16-bit) ≈ 0.5 MB.
  • A 30 cm scan at 0.5mm slices ≈ 600 slices (300 MB).
  • Multiple series (e.g., axial, coronal, contrast phases) with 4,000–16,000 slices total ≈ 2–8 GB.
• Conclusion: 8 GB aligns with a comprehensive, thin-slice study (e.g., whole-body or multi-phase).

4. Do You Need Reprocessed Data if You Have Raw Data?

Having raw data doesn’t eliminate the need for reprocessed 0.5mm slice data:

• Raw Data:
  • Requires vendor-specific software (e.g., GE Advantage Workstation) and expertise to reconstruct.
  • Impractical for most clinicians, including GPs, who lack reconstruction tools.
• 0.5mm Slice Data:
  • Viewable with standard DICOM viewers (e.g., RadiAnt, OsiriX).
  • Optimized for clinical use, ideal for diagnosis or sharing with your GP.
• Need Both?:
  • Clinical Use: 0.5mm DICOM data is essential for GPs/specialists.
  • Research/Reprocessing: Raw data is useful for re-reconstruction (e.g., different slice thickness or kernel), but this is rare and requires advanced tools.
  • Redundancy: If you can reconstruct raw data into identical 0.5mm slices, DICOM data isn’t needed, but reconstruction is complex.
• Recommendation: Request 0.5mm slice DICOM data for clinical use. Only request raw data for research or re-reconstruction, noting that some facilities may not provide it due to proprietary restrictions.

5. Is Original Raw Data Low-Resolution Images?

No, raw data is not low-resolution images:

• Raw Data: Unprocessed projection data, not images. It’s used to create images of any resolution (e.g., 0.5mm slices).
• Low-Resolution Images: These are reconstructed DICOM images with thicker slices (e.g., 5mm) or lower matrix sizes (e.g., 256 × 256).
• Clarification: If the clinic refers to “raw images,” they may mean thicker-slice reconstructions, not true raw data. Verify with the facility.

6. Practical Considerations

• Clarify with Facility:
  • Confirm if “raw data” is projection data or initial reconstructions.
  • Verify raw data file size and DICOM data contents (e.g., series included).
• Storage/Transfer:
  • 8 GB DICOM + 1–5 GB raw data requires significant storage (e.g., 16 GB USB or cloud).
  • Use secure methods (e.g., encrypted cloud, PACS) for sensitive data.
• Viewing:
  • DICOM: Use free viewers like RadiAnt or 3D Slicer.
  • Raw Data: Likely unusable without vendor-specific software.
• For GP:
  • Provide 0.5mm slice DICOM data with the radiologist’s report.
  • Raw data is rarely useful for clinical practice.

7. Summary

• File Sizes:
  • 0.5mm Slice DICOM: ~8 GB, reasonable for high-resolution scans.
  • Raw Data: Likely 1–4 GB, possibly 500 MB to 5–10 GB.
• Need for Reprocessed Data: 0.5mm DICOM data is essential for clinical use; raw data is only needed for re-reconstruction (rare).
• Raw Data: Not low-resolution images, but unprocessed projection data.

Contact the imaging facility for precise raw data sizes or to clarify data types. This document was generated based on a discussion on June 21, 2025.