Annex R – USB Connected Removable Devices

R.1 DICOM Mapping to media formats

Only one DICOM file set shall be stored in the first partition of a partitioned device. If the device is not partitioned, only one DICOM file set shall be stored on the device.

R.1.1 File System

The file system employed on these media shall be either the FAT16 file system or the FAT32 file system. The information in the boot sector of this partition shall be utilized by the file system to determine proper access to this media (see Microsoft Extensible Firmware Initiative FAT32 File System Specification).

Filenames used for DICOM files shall be further restricted to be in compliance with the File ID rules specified in Part 10. The File ID shall be the same as the filename.

Note: These rules limit the character set to being a subset of the DICOM default G0 character set, limit the filenames to be no more than 8 characters, and limit the directory tree to be no more than 8 levels deep. All of these restrictions are needed to comply with the most limited of the removable media.


R.2.1 Partitioning

These media may be partitioned or unpartitioned. The more common usage is partitioned.

Note: Operating system support for unpartitioned media varies. Most current operating systems expect partitioned media. Some restrict their support further and only support access to the first partition of this media. These support decisions are being driven by the high volume consumer items that utilize these mechanisms, such as digital cameras.

R.3 Physical Media interface

These devices may have a wide variety of overall physical characteristics. They shall provide a connector that complies with the USB 1.1 or 2.0 specifications for physical, electrical, signaling, and communications protocol. The electrical signaling and lower level USB protocol support shall comply with the USB 1.1 or 2.0 specifications. The device shall act as a Mass Storage Device, in accordance with the USB Mass Storage Class, as described in the Universal Serial Bus Mass Storage Class, Specification Overview and its subordinate and referenced documents.

Notes: 1. The USB base standard and the USB mass storage device standard includes specification for management of device addition and removal, and for negotiation of device command protocol capabilities. Support for these is normally part of the functions provided by the USB Mass Storage driver in an operating system.

2. The USB 2.0 specification specifies 3 speeds of operation, “low-speed”, “full-speed” and “high-speed” which are fully interoperable, and this profile does not distinguish between the speeds.

3. The intent is to allow removable 1.1 and 2.0 USB media to interoperate with 1.1 and 2.0 USB devices.