public ImageData(DicomDataset dataset, int frame)
{
    Dataset = dataset
        .Clone(DicomTransferSyntax.ExplicitVRLittleEndian); // ensure decompressed
    Geometry = new FrameGeometry(Dataset, frame);
    PixelData = DicomPixelData.Create(Dataset);
    Pixels = PixelDataFactory.Create(PixelData, frame);

    SortingValue = Geometry.DirectionNormal.DotProduct(Geometry.PointTopLeft);
}

var numberOfFrames = dicomFile.Dataset.GetSingleValue<int>(DicomTag.NumberOfFrames);

var sliceImageData = Enumerable.Range(0, numberOfFrames)
    .Select(frame => new ImageData(dicomFile.Dataset, frame));

var volumeData = new VolumeData(sliceImageData);