IEC 60601-2-44:2001/AMD1:2002

INTERNATIONAL IEC
STANDARD
60601-2-44
AMENDMENT 1
2002-09
Amendment 1
Medical electrical equipment –
Part 2-44:
Particular requirements for the safety of
X-ray equipment for computed tomography
Amendement 1
Appareils électromédicaux –
Partie 2-44:
Règles particulières de sécurité pour les équipements
à rayonnement X de tomodensitométrie

 IEC 2002 Droits de reproduction réservés  Copyright - all rights reserved
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– 2 – 60601-2-44 Amend. 1  IEC:2002(E)

FOREWORD
This amendment has been prepared by subcommittee 62B: Diagnostic imaging equipment, of

IEC technical committee 62: Electrical equipment in medical practice.

The text of this amendment is based on the following documents:

FDIS Report on voting
62B/472/FDIS 62B/478/RVD
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until 2004-06. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of April 2006 have been included in this copy.
_____________
INTRODUCTION
In the second edition of this Particular Standard six definitions were changed compared with the
first edition. These changes, however, were not in line with the definitions used in international
scientific publications. This amendment to the Particular Standard mainly corrects those
definitions and adds more detailed definitions of the dose values to be displayed.
Page 8
2 Terminology and definitions
Replace the existing definitions 2.101 and 2.106 to 2.110 by the following:

2.101
CT SCANNER
X-RAY EQUIPMENT for COMPUTED TOMOGRAPHY (CT)
diagnostic X-ray system intended to generate cross-sectional images of the body by computer
reconstruction of X-ray transmission data obtained at different angles. This generic type of
device may include signal analysis and display equipment, PATIENT SUPPORT, support parts
ACCESSORIES
and
NOTE Secondary imaging processing is not included in the scope of this standard.
2.106
COMPUTED TOMOGRAPHY DOSE INDEX 100 (CTDI )
integral of the DOSE PROFILE produced in a single axial scan along a line perpendicular to
the TOMOGRAPHIC PLANE from –50 mm to +50 mm, divided by the product of the number of
TOMOGRAPHIC SECTIONS N and the NOMINAL TOMOGRAPHIC SECTION THICKNESS T:

60601-2-44 Amend. 1  IEC:2002(E) – 3 –

+50 mm
D (z)
=  dz
CTDI
∫
N × T
−50 mm
where
D(z) is the DOSE PROFILE along a line z perpendicular to the TOMOGRAPHIC PLANE, where

dose is reported as ABSORBED DOSE to air;

N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-RAY

SOURCE;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS.

NOTE 1 The term CTDI has been introduced as a more representative value for dose than the traditional CTDI
integrated from –7T to +7T as defined by the FDA in 21 CFR 1020.33 .
NOTE 2 The dose is reported as ABSORBED DOSE to air. This is required in order to avoid present confusion, as
some MANUFACTURERS of CT SCANNERS express dose values calculated as ABSORBED DOSE to air and others as
ABSORBED DOSE to polymethyl-methacrylate (PMMA).
Although CTDI refers to ABSORBED DOSE to air, for practical purposes the evaluation of ABSORBED DOSE to
air within a PMMA dosimetry PHANTOM is well approximated by measurement of the AIR KERMA with an
ionization chamber in the PHANTOM.
NOTE 3 This definition assumes that the DOSE PROFILE is centred on z = 0.
NOTE 4 A single axial scan is typically a 360° rotation of the X-RAY SOURCE.
2.107
CT PITCH FACTOR
in helical scanning the ratio of the PATIENT SUPPORT travel ∆d along the z direction per rotation
of the X-RAY SOURCE divided by the product of the NOMINAL TOMOGRAPHIC SECTION THICKNESS T
and the number of TOMOGRAPHIC SECTIONS N:
∆d
CT pitch factor =
N ×T
where
Δd is the PATIENT SUPPORT travel along the z direction per rotation of the X-RAY SOURCE;
T is the NOMINAL TOMOGRAPHIC SECTION THICKNESS;
N is the number of TOMOGRAPHIC SECTIONS produced in a single axial scan of the X-RAY
SOURCE.
2.108
TOMOGRAPHIC SECTION
volume over which TRANSMISSION data of X-RADIATION are collected in a single axial scan
NOTE In a CT SCANNER with multiple detector elements along the z-axis, it is the volume over which data are
collected by a single acquisition channel (selected grouping of elements) and not the total volume irradiated.
2.109
TOMOGRAPHIC SECTION THICKNESS
FULL WIDTH AT HALF MAXIMUM of the SENSITIVITY PROFILE taken at the iso-centre of a
TOMOGRAPHIC SECTION
2.110
NOMINAL TOMOGRAPHIC SECTION THICKNESS
in CT SCANNERS the TOMOGRAPHIC SECTION THICKNESS which is selected and indicated on the
CONTROL PANEL
———————
See bibliography
– 4 – 60601-2-44 Amend. 1  IEC:2002(E)

NOTE In helical scanning the thickness of a reconstructed image depends on the helical reconstruction algorithm

and pitch, and hence this thickness may not equal the NOMINAL TOMOGRAPHIC SECTION THICKNESS. The thickness of
the reconstructed image may be indicated or selected prior to the helical scan.

Page 13
6.8.101 Reference to ACCOMPANYING DOCUMENTS

Delete the following lines:
Frequency of SUPPLY MAINS . 6.1 h)

Power input. 6.1 j)
Add the following line:
Protection against STRAY RADIATION .29.208
Page 19
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