The benefits of using object identifiers for quantities and units

in human physiology

Jean-Paul LemaireAssociate Rapporteur of ITU-T SG 17/Q.9 (Telebiometrics)

ITU-T Workshop on “Radioactivity safety and security threats protection and telemedical support for irradiated people”

Geneva 30 Aug 2011

Summary

This presentation explains how object identifiers and ASN.1 can be used in data exchange in telemedicine which is very useful in radioprotection when areas are potentially contaminated :

• Object identifiers can identify unambiguously quantities, units and symbols.

• ASN.1 can be used to define objects equivalent to tables but directly usable by applications.

• ASN.1 is also useful to describe messages and provides several encoding rules.

Object identifiers• Object identifiers have been designed to assign

unambiguous identifiers to many kinds of objects involved in telecommunications:• network management• directory systems (object classes, attributes, etc).

• Object identifiers are now defined in ITU-T X.660 series of ITU-T Recommendations and ISO/IEC 9834 standard.

• The object identifiers are organized in a hierarchical structure administered by ITU-T and ISO: the first level contains three arcs:• arc 0: itu-t, administered by ITU-T• arc 1: iso, administered by ISO• arc 2: joint-iso-itu-t, administered jointly by ITU-T and ISO.

The first arcs of the registration treeroot

itu-t(0) iso(1) joint-iso-itu-t(2)

recommendation(0)

a(1) z(26)

standard(0) member-body(2) asn1(1) ds(5)

An object identifier is defined by the list of the arcs from the root. Each arc can be defined by a number or a number and an identifier:•in ASN.1 notation: {itu-t(0) recommendation(0) a(1)}•in dot notation: 0.0.1.

Another notation: OID-IRI• The ASN.1 and dot notations have been completed by a

new one, OID-IRI which allows usage of human-friendly notation not limited to latin alphabets but which allows Unicode alphabets.

• An OID-IRI is a list of Unicode labels separated by / characters:/ITU-T/Recommendation for {itu-t(0) recommendation(0)}/ISO/Member-Body for {iso(1) member-body(2)}

• With OID-IRI, it is possible to define “long arcs” which are Unicode labels which permits, in the joint-iso-itu-t branch, to access directly OIDs not immediately beneath the root.

The Telebiometrics subtreeFor telebiometrics and e-health, a specific OID branch has been defined: {joint-iso-itu-t(2) telebiometrics(42)} with the associated long arc /Telebiometrics

{2 42} Telebiometrics

tmm(1) TMM

human-physiology(2) Human_Physiology

telehealth-protocol(3) Telehealth_Protocol

physics(4) Th_Physics

chemistry(5) Th_Chemistry

biology(6) Th_Biology

culturology(7) Th_Culturology

psychology(8) Th_psychology

patients(1) Patients

medical-staff(2) Medical_Staff

observers(3) Observers

pharmaceutical-staff(4) Pharmaceutical_Staff

laboratories(5) Laboraties

drug-manufacturers(6) Drug_Manufacturers

medical-device(7) Medical_Device

medical-software(8) Medical_Software

medical-insurance(9) Medical_Insurance

medical-records(10) Medical_Records

measures(1) Measures

The risks in e-health

There are several risks in e-heath:• risks in data transmission:

• modification of data during transmission• divulgation of private information

They are covered by e-health-protocol (X.th1, future X.1080.1).• risks in misinterpretation of data:

• great number of quantities particularly in chemistry and biology• Several units and symbols associated to a given quantity.

They are covered by using unique object identifiers for quantities, units and symbols. These object identifiers will be defined in the five specific parts of X.th series:

• X.th2 (physics)• X.th4 (biology)• X.th6 (psychology)

• X.th3 (chemistry)• X.th5 (culturology)

Object identifiers assigned to quantities, units and symbols

{2 42 1 1}/Telebiometrics/TMM/

Measures

quantities(1)Quantities

units(2)Units

symbols(3)Symbols

physics(1)Physics

chemistry(2)Chemistry

biology(3)Biology

culturology(4)Culturology

psychology(5)Psychology

Definitions of quantities

Each quantity is defined using the ASN.1 information object class QUANTITY which defines:

• the name (in English and optionally in French)• the associated symbols defined by a name, an object

identifier completed by a RELATIVE-OID-IRI• the unit • the modalities• the assigned object identifier completed by a RELATIVE-OID-IRI.

Example of quantity

The sodium element is defined as follows:sodium QUANTITY ::= {

"sodium" USING SYMBOLS {{"Na"} IDENTIFIED BY

{id-symbols sodium(11)} AND "Na"}MEASURED IN {percent} FOR MODALITIES

{id-tango}IDENTIFIED BY {id-quantities sodium(11)}AND "Sodium" }

Example of quantity

The definition specifies:• the name of the object • the symbol “Na” with an object identifier

completed by a RELATIVE-OID-IRI • the unit defined as informational object

percent, the modalities and the associated object identifier completed by a RELATIVE-OID-IRI.

Definitions of units

Each unit is defined using the ASN.1 information object class UNIT which defines:

• the name (in English and optionally in French)• the associated symbol• the assigned object identifier and RELATIVE-OID-IRI.

• the other units from which this unit is derivedA unit which is a multiple or submultiple of a another one (for example millimeter) is related to basic unit with a factor which is a power of 10.

Example of unit

The kg/l is defined as follows:

kilogramPerLitre UNIT ::= {"kilogramPerLitre" USING SYMBOLS {{{"kg . l" , superscriptMinus , superscriptOne}} IDENTIFIED BY {id-symbols kilogramPerLitre(0)}

AND "KilogramPerLitre"}IDENTIFIED BY {id-units kilogramPerLitre(1)}AND "KilogramPerLitre" DERIVED BY PRODUCT OF {kilogram}

DIVIDED BY {litre}}

Example of unit

This definition specifies:• the name kilogramPerLitre• the associated symbol kg.l-1 with the corresponding object identifier and RELATIVE-OID-IRI•the object identifier completed by the RELATIVE-OID-IRI. Its also specifies that this unit is derived from two other units kilogram and litre.

Definition of symbols

A symbol is defined by:• One or more character string• The attributes of the strings (for example italic)• the assigned object identifier completed by a RELATIVE-OID-IRI.

Example:

sodium-symbol SYMBOL ::=

{{"Na"} IDENTIFIED BY {id-symbols sodium(11)} AND "Na"}

Relations between quantities units and symbols

• The information objects related to quantities and symbols are linked together so starting from a quantity, it is possible to find the possible units and symbols.

• The multiples and submultiples of a unit are also linked to the base unit.

Units

Symbols

QuantitiesPhysicsChemistryBiologyCulturologypsychology

Conclusion

The definition of object identifiers for quantities and units enforces the reliability and security of medical data transmission because they can be automatically processed and imported from a unique repository (which does not exist nowadays).

They also permit the presentation of test results in various forms and conform to the usages of the medical practitioners because the symbols and multiples or submultiples of basic units are included in the informational object definitions.