IEC 62985-2019 PDF

Full title and description

St IEC 62985-2019 — Methods for calculating size specific dose estimates (SSDE) for computed tomography. The standard defines standardized methods and requirements for calculating, displaying and recording size‑specific dose estimate (SSDE) and associated size metrics such as water‑equivalent diameter (DW), including SSDE(z) and DW(z), and it addresses verification/validation using defined test objects and phantoms.

Abstract

IEC 62985:2019 specifies procedures for CT scanners (that can display/report CTDIvol) and for radiation dose index monitoring software (RDIMS) to calculate, present and store SSDE and related quantities. The document includes methods to derive a reference water‑equivalent diameter from phantom scans, requirements for manufacturer‑implemented DW calculations, and validation/verification tests using the prescribed test objects. A corrigendum issued in 2022 has been incorporated into available copies.

General information

• Status: Published; international standard (with corrigendum included in later copies).
• Publication date: 13 September 2019 (main publication).
• Publisher: International Electrotechnical Commission (IEC).
• ICS / categories: 11.040.50 (Radiographic equipment).
• Edition / version: Edition 1.0.
• Number of pages: 21 (IEC published version).

(Publication details and stability information as listed on the IEC webstore; corrigendum COR1 published June 2022 has been issued for this document.)

Scope

Applies to CT scanners capable of displaying/reporting CTDIvol (per IEC 60601‑2‑44) and to radiation dose index monitoring software (RDIMS) for the purpose of calculating, displaying and recording SSDE and its components. The standard provides: standardized definitions for SSDE, SSDE(z), DW and DW(z); a procedure to determine a reference DW,REF(z) using two cylindrical water phantoms and one or more anthropomorphic phantoms that meet the document’s specifications; and test/validation methods to compare a manufacturer's implemented DW (DW,IMP) against DW,REF. The standard also describes averaging methods for SSDE and DW over reconstruction length.

Key topics and requirements

• Definition and standardized computation of SSDE, SSDE(z), water‑equivalent diameter (DW) and DW(z).
• Requirements for CT scanners and RDIMS to calculate, display and record SSDE and supporting size metrics.
• Method to determine a reference water‑equivalent diameter (DW,REF) using two cylindrical water phantoms and anthropomorphic phantom(s).
• Validation and verification procedures to test manufacturer‑implemented DW calculations (DW,IMP) against DW,REF using specified test objects and methods.
• Specification of averaging methods (over reconstruction length) and reporting conventions for SSDE and DW values.
• Notes and limitations about SSDE methodology and guidance for accompanying documentation (annex material addressing uncertainties and special clinical scenarios).

These requirements are intended to harmonize how patient‑size corrections are computed and reported across CT vendors and dose‑monitoring systems.

Typical use and users

Primary users include medical physicists, clinical radiology departments, CT equipment manufacturers, RDIMS/dose‑tracking software vendors, regulatory bodies and accreditation/QC teams who implement dose monitoring and patient‑specific dose reporting. The standard is used where facilities or vendors need a consistent, validated method to derive SSDE and DW from CT data and to integrate those values into dose reports or surveillance systems.

Related standards

Key related and referenced documents include IEC 60601‑2‑44 (particular requirements for CT scanner safety and radiation reporting), IEC TR 60788 (additional CT/dosimetry guidance referenced by national publishers of the text), and professional Task Group reports that established SSDE conventions (e.g., AAPM TG‑204 and TG‑220 which introduced SSDE and water‑equivalent diameter concepts). National adoptions and corrigenda (EN/UNE/BS versions and amendments) exist and may include editorial changes or national implementation notes.

Keywords

SSDE; size‑specific dose estimate; water‑equivalent diameter (DW); DW(z); CTDIvol; computed tomography; RDIMS; dose monitoring; patient size correction; phantom validation.

FAQ

Q: What is this standard?

A: IEC 62985:2019 is an international standard that defines methods for calculating, displaying and recording size‑specific dose estimates (SSDE) and related size metrics (water‑equivalent diameter and per‑position values) for CT scanners and dose‑index monitoring software.

Q: What does it cover?

A: It covers the algorithms and procedures for computing SSDE, SSDE(z), DW and DW(z); prescribes how to derive a reference water‑equivalent diameter using specified phantom scans; and sets validation/verification tests for manufacturer‑implemented DW calculations. It also addresses reporting and averaging conventions for SSDE over reconstruction length and provides annex guidance on limitations and uncertainties.

Q: Who typically uses it?

A: Medical physicists, CT manufacturers and software vendors (RDIMS/dose tracking), radiology QA teams, and regulators use this standard to ensure consistent patient‑size dose estimation and reporting across equipment and monitoring systems.

Q: Is it current or superseded?

A: IEC 62985:2019 is the published international document (edition 1.0, published 13 Sep 2019) and a corrigendum (COR1) was issued in June 2022; copies sold by IEC/webstore note that the corrigendum contents have been included. National adoptions and implementations may carry amendments or be superseded locally (for example, some national catalogues record later adoptions or supersessions); always check the national standards body for the status in a given country.

Q: Is it part of a series?

A: IEC 62985 is a standalone standard addressing SSDE methodology, but it sits within the broader medical imaging standards family (TC 62/SC 62B) and is operationally linked to other CT and dosimetry standards such as IEC 60601‑2‑44; it also builds on widely used dosimetry guidance from professional bodies (e.g., AAPM TG‑204, TG‑220).

Q: What are the key keywords?

A: SSDE, DW (water‑equivalent diameter), CTDIvol, dose monitoring, RDIMS, patient size correction, phantom validation, CT dosimetry.