Most CT and MR scanners incorporate SSD and MIP capabilities,
and the latest generation is capable of VR. However, a more
efficient option usually is to export the data to a separate
workstation, either one developed specifically for medical imaging
or a standard workstation running FDA-approved 3D reconstruction
software.
As in so much else in computing, the rule is that newer, bigger,
and faster is generally superior to older, smaller, and slower.
However, the capacity one needs (and how much money one needs to
spend) depends on which types of display are desired (SSD and MIP
require less capacity than VR), how many studies will be done, and
which modalities will be used. Software suitable for one's goals
should be selected, after which the workstation can be chosen.
Much 3D reconstruction software is written for UNIX, although
programs for Windows NT or Windows 2000 or the new Macintosh
systems are becoming available for larger desktop computers.
Picture archiving and communications systems (PACS) now in
development will have 3D processing capabilities. Some programs
handle data from any modality, whereas others are confined to
ultrasound or CT/MR. The types of displays possible with different
programs vary, as do the anatomic sites for which they are written.
For example, there are programs written specifically for virtual
colonoscopy or for measuring vascular calcium. Some programs can be
purchased, whereas only licenses are available for others. Prices
range from $1,000 to $16,000 or more.
Typically, workstations used for volumetric displays have two
processors running at a speed of at least 375 MHz; the newest
dedicated medical imaging workstations have clock speeds as high as
1.7 GHz. One workstation boasts up to 4 GB of dual-channel RDRAM
(RAMBUS dynamic random access memory). Various Level 1 and Level 2
caches are available; larger is better. The larger the local
storage capacity, the less time the workstation spends fetching
data; capacities as large as 292 GB are available.