Supplement 94xx: CT Radiation Dose Reporting (Dose SR)CT Dose Report

DICOM WG2124-Jan-2007

Bernhard. Hassold@siemens.com

2CT Dose Reporting with DICOM Structured Report (SR)

A new supplement has been created based on the request of IEC MT30 CT

The CT Dose Report, as defined in the supplement is based on supplement 94 concerning X-Ray radiation.

The requirements of the CT SR dose reporting were presented on the RSNA and distributed in WG21 (see the following slides).

The Supplement was discussed by DICOM WG21 CT in July and shall be released in the near future (March of 2007).

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DICOM Structured Report Dose The Radiation Dose reporting shall be defined through a

DICOM Structured Report (SR) object template and SOP Class. This SR object could be routed to an appropriate Radiation Safety Reporting System. A system that claims conformance to such a SR object would then be expected to appropriately deal with such data items.

The proposal for “CT Dose Reporting” is derivated from the Supplement 94: Diagnostic X-Ray Radiation Dose Reporting (Dose SR)

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Irradiation Event and Structured Report An irradiation event is the occurrence of radiation being applied to

a patient in a single continuous time-frame between the start (release) and the stop (cease) of the irradiation.

A differentiation is made between dose relevant data that has to be provided “per event” and those data that represent “accumulations”.

Any on-off switching of the radiation source during the event shall not be treated as separate events, rather the event includes the time between start and stop of radiation as triggered by the user. E.g., a pulsed fluoro X-Ray acquisition shall be treated as one single irradiation event.

An amount of “additional data” to describe the physical context and the quality of the irradiation exposure has to be recorded along with the dose values.

The irradiation event is the “smallest” information entity to be recorded in the realm of Radiation Dose reporting. Patient Information and study information shall be stored with the DICOM Dose SR object.

An event resulting in creation of a DICOM Image SOP Instance or SOP series shall be included as a reference.

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X-Ray SR Dose IOD Modules and StructureIE Module Reference Description

Patient Patient C.7.1.1 Describes the identity of patient

Clinical Trial Subject C.7.1.3 Identify clinical trial subject

Study General Study C.7.2.1 Describes the study performed upon patient

Patient Study C.7.2.2 Describes information about study

Clinical Trial Study C.7.2.3 Identify context of clinical trial

Series SR Document Series C.17.1 Defines attributes of the SR document

Clinical Trial Series C.7.3.2 Identify context of clinical trial

Frame of Reference

Synchronization C.7.4.2 Synchronization to patient study

Equipment General Equipment C.7.5.1 Attributes to identify the equipment

Document SR Document General C.17.2 General context of SR document

SR Document Content C.17.3 Specifies the attributes contained in the SR

SOP Common C.12.1 DICOM basic for definition of object

CT Accumulated Irradiation Dose Study

template Accumulated irradiation for an entire examination

CT Irradiation Event template 1 to n separate irradiation events

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Summary of Accumulated Dose

The report summary shall give an overview of the whole patient examination and the accumulated dose applied.

The patient information, the patient study information and the general equipment information is stored within the general part of the SR

The total DLP of a patient examination is required. The accumulated irradiation effective dose in mSv may

stated. This is optional! The method of evaluation is stated The measuring devices are stated, if applicable The generation, the relationship and the dose of each event

are stated in separate sequences.

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Content of the CT Irradiation Event The clinical character of the examination shall be stated

The type of acquisition shall be stated The relation to the DICOM study and image objects shall be

stated. The relation to the patient region shall be given by body

part examined The parameters of dose evaluation shall be given The parameters of the generation of the irradiation and

acquisition shall be stated. The dose of a single event shall be stated.

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CT Acquisition Sequence

The acquisition type is stated: sequenced or spiral. Fluoroscopy flag is stated if applicable. A reference id (Radiation event UID) is stated to identify

related series and images within this patient study.

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CT Acquisition Parameters

The tube voltage and the tube current are stated. The effective exposure in mAs is stated. The exposure time and the scanning length are stated. Acquisition parameters related to the volume acquisition

are stated (collimation, pitch factor).

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CT Irradiation Event Dose Summary

A comment related to exam and dose can be appended. For each CT Acquisition (irradiation event):

The CITDIvol and DPL are stated. The corresponding CTDIfreeair is stated.

The effective dose may be stated, optional. The detection method and the parameters used are stated.

The reference values for dose estimation and calculation are stated, e.g. calibration factor, effective dose type

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What happens:

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01 May 31, 2006 Created, draft distributed

02 August 01, 2006 Correctives included: FDA (S. Stern), GE Healthcare (D. Littlejohn), Philips (S. Gotman), Siemens (B. Hassold)

03 September 20, 2006 Correctives included: Position of IEC/SC 62B Position of IEC/SC 62, GEHC Comments (D. Littlejohn), Position of the 10th Meeting of the Maintenance Team IEC/62B/MT30

04 October 20, 2006 Correctives included: FDA (S. Stern), GE Healthcare (D. Littlejohn, Harry Solomon),

05 January 08, 2007 Correctives included: GE Healthcare (D. Littlejohn, Harry Solomon),

06 January 25, 2007Correctives include: WG

History of Versions

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• IEC WG 30: Norbert Bischof, Stanley Stern, Christoph Suess• FDA: Stanley Stern,…• Nema: Stephen Vastagh,… • DICOM: Stephen Vastagh, WG21• Response of Manufactures: GE, Philips, Siemens

Who was Involved: