The DICOM Data Format Explained
The Digital Imaging and Communication in Medical (DICOM) file type is an international standard for the storage of medical imagery and the associated patient information. First introduced in 1993, DICOM is used across almost all medical devices, from ultrasound machines through to CT & MRI scanners1. Having a universal standard for the file format and storage medium of the medical images assists greatly in developing innovative solutions for better acquiring the images and visualising the images after patient scanning.
In the case of CT/MRI & PET scanners, which take hundreds, if not thousands, of individual slice images, each slice is stored as a .dcm file extension within a directory of other .dcm files.
Volume Rendering Explained
At present, constrained by a 2D monitor and atleast 27 years of ingrained radiological practices, DICOM viewers load all of the individual slices as seen from three (3) orthagonal views; axial, sagittal and coronal (top, front and side). Medical professionals are then able to scroll through the patient in each plane slice by slice to identify abnormalities.
A typical 2D slice presents a single snapshot of the patient at a time and relies on highly trained radiologists and medical practitioners to interpret the 2D info and visualise it in 3D in their head.
At the time of acquisition (when the scan is taken), the individual slices are captured at particular thicknesses (from as low as 0.1 millimeters upwards). Volume rendering CT scans and other medical images becomes possible by knowing this slice thickness, providing a ‘depth’ to each slice which can be multiplied by the area / areas of the slices to calculate volume and digital compositing the volumes of each slice together to create a single cohesive 3D volumetric model.
Our platform takes the highly complex tasks of windowing scans based upon the different densities of the tissues into a simple slider and also includes a 3D slicer tool to allow you to occlude (hide) certain areas of the scan to allow the viewing of ‘deeper’ internal areas of the scan.
Whilst the file folder was hidden in the video above to protect patient confidentiality, it is clear to see that conversion from a .DCM or .NII file is as simple as clicking “Load Dicom” in the top left corner and then choosing your specified DICOM file. The program takes between 5 and 90 seconds for the process of volume rendering CT scans, if a scan takes longer than 2 minutes, please submit feedback and we can help you configure your scan for conversion.
Singular Volumetric Rendering Platform – 2D image to 3D volume in less than 60 seconds
Whilst the Volume Rendering process described in this blog post may sound simplistic, being the stacking of different slices, there are thousands of variations of DICOM tags, possible orientations of scans and the process of standardising and windowing the different densities for viewing in 3D is highly complex. If you’d like a virtual demo of the 3D volume renders in Virtual Reality, take a look at our VR solution at MedVR.