B.3 STD-XA1K-CD Application Profile Class Requirements 7
B.3.1 SOP Classes and Transfer Syntaxes 7
B.3.2 Physical Media And Media Formats 8
C.2.1 Roles 9
C.3 General Class Profile 9
C.3.2 Physical Media and Media Formats 9
E.1 Profile Identification 10
E.3 STD-CTMR ProfileS 10
E.3.1 SOP Classes and Transfer Syntaxes 10
E.3.2 Physical Medium And Medium Format 12
Annex X (Normative) - General Purpose DVD with Compression Interchange Profiles 13
X.1 Profile Identification 13
X.2 Clinical Context 14
X.2.1 Roles and Service Class Options 14
X.3 STD-GEN-DVD and STD-GEN-SEC-DVD Profile ClassES 16
X.3.1 SOP Classes and Transfer Syntaxes 16
X.3.2 Physical Medium And Medium Format 17
X.3.3 Directory Information in DICOMDIR 17
X.3.4 Other Parameters 19
X.3.5 Security Parameters 19
2 Normative references 21
4 Symbols and abbreviations 22
Annex X 120 mm DVD Medium (Normative) 23
X.1 DICOM mapping to media format 23
X.1.1 Media Character Set 23
X.1.2 DICOM File-set 23
X.1.3 DICOM File ID Mapping 24
X.1.4 DICOM File Management Information 24
X.2 Filesystem 24
X.2.1 UDF File system 24
X.2.2 ISO 9660 File system 26
X.3 Media formats 26
X.3.1 DVD 26
Scope and Field of Application
New clinical applications have requirements for higher capacity media formats. This is true for general-purpose applications and is also especially important in the support of the 1024 matrix size that is becoming more common for digital coronary angiography. General (peripheral and neuro) angiography similarly requires significantly higher capacity than is afforded by CD-R.
DVD-RAM was introduced into the standard with Supplement 40 but is not suitable for some applications, particularly since it is not readable on many users’ PCs without a special drive. At the time, support for DVD-R and DVD-RW and DVD+RW was not added to the standard due to lack of a clear consensus as to which medium would prove popular as well as the lack of multiple vendors for media and drives. This situation has now changed, with multiple vendors available for all these media types.
The question remains then as to which to pick for new DICOM interchange applications. Since there are few if any fair or meaningful criteria on which to make such a choice, and since the ability to interchange media that may be rewritten seems to be less important for many applications than the need to be able to write an entire piece of media and read it elsewhere, the unusual choice of excluding the File Set Updater role and specifying only the File Set Creator and Reader roles in a media-agnostic manner has been taken.
Choice of a Filesystem
All DVD media makes use of the UDF file system. DVD-RAM as presently supported in the standard defines the use of UDF 1.5.
The need to specify the level of UDF that must be supported by a File Set Reader is avoided by specifying that an FSR must be able to read any UDF version up to 2.01 (the most recent version), since that implies that earlier versions (1.02, 1.5 and 2.0) will also be supported.
Mandatory support for reading both UDF and ISO 9660 is included to facilitate migration from legacy CD-R implementations, which use ISO 9660, as well as to support the industry standard filesystem for DVD, UDF.
choice of a Physical Medium
It should be stressed that DICOM is not attempting to standardize an archive medium, only an interchange medium (though many applications typically write interchange media using the same physical drive and software as is used for writing single archival volumes for shelf management). It is, however, desirable that media chosen for interchange be resilient and non-volatile.
The input of other working groups that may use new media has been sought. While the ultrasound working group (Working Group 12) places a high priority on rewritable media and is interested in a replacement for magneto-optical disc (“MOD”), the Cardiovascular Information Group (Working Group 1) places a high priority on the ability to be “ubiquitously readable”. That is, the ability to read the media on any modern PC without additional specialized hardware. The DVD-R, DVD-RW, DVD+R, DVD+RW, and DVD-ROM) media meets this ubiquitous readability requirement, as they can be read in the vast majority of conventional DVD-ROM drives used today (DVD-RAM does not share this feature).
Furthermore, the rewritable feature requested by WG12 for “internal” departmental use and reusability is felt by WG1 to be a potentially undesirable feature for exchanging information between institutions, as growing concerns about security and confidentiality are better addressed by an exchange format that cannot readily be altered. To assure that data has not been altered requires the use of cryptographic security mechanisms such as those defined in PS 3.15, but the use of disk-at-once writing of ablative media such as DVD-R goes some way to meeting this requirement. Incremental writing of DVD-RW or DVD+RW does not meet this requirement.
Finally, it is recognized that there is a need (albeit rare) to mass-produce media content on DVD-ROM (for example, for teaching purposes). As this meets the requirements of “ubiquitously readable”, and is fully compatible with DVD-R file formats and readers, this media is also included on the list of acceptable media.
An allied consideration is that of the ability to append information onto media. Historically, this feature was included in the CD-R application profile, with the intent that “core labs” might want to add information such as secondary captures onto the recorded media. This feature has been used rarely (if at all), and in routine practice; CD-R media containing DICOM information is not altered after written. As mentioned above, one of the current concerns in the area of medical information security and confidentiality is the assurance that what is received is in fact exactly what was sent. For these reasons, the DVD application profile does not include a description of a File Set Updater. With this capability removed, the ability to assure the integrity of the data is increased, and interoperability is improved, as the precise format and wavelength response of the media does not need to be specified or adhered to (this is purely a consideration for the File Set Creator and its associated DVD-R recorder).
As described in the Scope and Field of Application of Supplement 40, when the suggestions of the various groups were taken into account, it became apparent that no single choice of DVD-based media would satisfy the unique requirements of every application. Accordingly, it was decided that the specific types of DVD media would be added to the standard as the need arises and as the technology becomes available from multiple media and drive vendors.