1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA XR 25-2010Computed Tomography Dose CheckNEMA Standards Publication XR 25-2010 Computed Tomography Dose Check Published by: National Electrical Manufacturers Association 1300 North 17th Street, Suite 1752 Rosslyn, Virginia 22
2、209 www.nema.orgwww.medicalimaging.org Copyright 2010 by the National Electrical Manufacturers Association. All rights, including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the Inter
3、national and Pan American Copyright Conventions. NOTICE AND DISCLAIMER The information in this publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed. Consensus does not necessarily mean that there
4、 is unanimous agreement among every person participating in the development of this document. National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development pr
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10、 or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for additional
11、views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other sta
12、tement of compliance with any health or safetyrelated information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. XR 25-2010 Page i CONTENTS Forewordii Member Company List .iii History.iv Section 1 OVERVIEW 1 1.1 Scope.
13、1 1.2 Rationale 1 1.3 References 1 1.3.1 Normative References 1 1.4 Definitions 2 1.5 Abbreviations. 2 Section 2 DOSE NOTIFICATIONS AND DOSE ALERTS 3 2.1 Dose Notifications 3 2.1.1 Configuration. 3 2.1.2 Checking Prior to SCANNING 3 2.1.3 Audit Capability for PROTOCOLS and PROTOCOL ELEMENTS . 3 2.1.
14、4 Dose Notification Format. 4 2.2 Dose Alerts 4 2.2.1 Configuration. 4 2.2.2 Checking Prior to SCANNING 4 2.2.3 Checking Prior to Saving PROTOCOLS and Audit Capability . 5 2.2.4 Dose Alert Format . 5 ANNEX A (Informative) . 6 Copyright 2010 by the National Electrical Manufacturers Association. XR 25
15、-2010 Page ii Foreword This standard is intended to be used by medical imaging device manufacturers in the design and manufacture of CT scanner equipment. This standard was developed by the CT Group of the X-Ray Imaging Section of the Medical Imaging however, for interventional type PROTOCOL ELEMENT
16、S, alternate means may be used such as values in mGy/s. If there are no preprogrammed limits, checking is not required. The system is not required to display a notification if no corresponding NOTIFICATION VALUES have been set. To exceed a NOTIFICATION VALUE, the system shall require the operator to
17、 reconfirm the chosen PROTOCOL ELEMENTS before proceeding to the SCAN. The system shall permit the operator to enter a diagnostic reason (of up to 64 characters) at the operators discretion. The system does not have to require the input of such reason(s) in order to proceed. When a SCAN is performed
18、 that exceeds a NOTIFICATION VALUE, the system shall record the date and time, a unique study identifier, the NOTIFICATION VALUE(S) that were exceeded, and the corresponding dose index value(s) that triggered the notification and any diagnostic reason provided for proceeding after receiving a notifi
19、cation. This record shall be available for site review and audit. 2.1.3 Audit Capability for PROTOCOLS and PROTOCOL ELEMENTS The system shall be able to generate a list of all PROTOCOLS and PROTOCOL ELEMENTS with their corresponding NOTIFICATION VALUES. If the NOTIFICATION VALUE is not set for a par
20、ticular PROTOCOL ELEMENT, the list will indicate this status. The system shall generate the list on request of the user. Copyright 2010 by the National Electrical Manufacturers Association. XR 25-2010 Page 4 2.1.4 Dose Notification Format The notification shall include at least three elements: a tit
21、le, a body, and operator interactions (including a field to enter diagnostic reason(s). The title of the notification shall be the text in the following box: DOSE NOTIFICATION The body of the notification message shall identify the NOTIFICATION VALUE(S) that would be exceeded, and the corresponding
22、estimated dose index value(s), and may provide additional information for clarity. The interactions shall allow the operator to: (1) Enter diagnostic reason (optional) then confirm to proceed, or (2) Go back and adjust SCANNING PARAMETERS 2.2 DOSE ALERTS 2.2.1 Configuration Manufacturers shall provi
23、de a means for users to enter, save, and modify ALERT VALUE(S) in terms of CTDIvol, DLP, or both. 2.2.2 Checking Prior to SCANNING For each EXAMINATION, at each position on the z-axis in the DICOM patient coordinate system, the system shall accumulate values for the total CTDIvol and shall accumulat
24、e the total DLP as the EXAMINATION proceeds. The system shall reset the accumulated values to zero when an EXAMINATION is closed. The system may set the accumulated total CTDIvolto zero when the DICOM patient coordinate system shifts, e.g., when the patient changes position on the table. The system
25、is not required to accumulate values for scan projection radiography. When a PROTOCOL ELEMENT GROUP is confirmed, the system shall display an alert (see 2.2.4) on the operators console if the accumulated CTDIvolor the accumulated DLP, plus the estimated values for the confirmed PROTOCOL ELEMENT GROU
26、P, exceeds the corresponding ALERT VALUE. The alert shall be displayed prior to the start of the SCAN, and shall never interrupt the SCAN. Some PROTOCOL ELEMENTS, such as bolus tracking or interventional, may not have a predefined number of rotations but may have other pre-programmed limits on the n
27、umber of exposures or exposure time. When estimating the CTDIvoland DLP for these types of PROTOCOL ELEMENTS, the estimate shall assume that the SCAN proceeds to those limits for PROTOCOL ELEMENTS such as bolus tracking; however, for interventional type PROTOCOL ELEMENTS, alternate means may be used
28、 such as values in mGy/s. If there are no preprogrammed limits, checking is not required. The system is not required to display an alert if a corresponding ALERT VALUE has not been set. To proceed with SCANNING when an ALERT VALUE has been exceeded, the system shall require the operator to enter his
29、/her name and reconfirm the chosen PROTOCOL ELEMENTS before proceeding to the SCAN. The system shall also provide password-protection capability that prevents execution of the SCAN unless the correct password is entered. The activation of the password-protection capability may be configurable. The s
30、ystem shall permit the operator to enter a diagnostic reason (of up to 64 characters) at the operators discretion. The system does not have to require the input of such reason(s) in order to proceed. Copyright 2010 by the National Electrical Manufacturers Association. XR 25-2010 Page 5 When a SCAN i
31、s performed that exceeds an ALERT VALUE, the system shall record the date and time, the operators name, unique study identifier, the ALERT VALUE(S) that were exceeded, and the corresponding dose index value(s) that triggered the alert and any diagnostic reason provided for proceeding after receiving
32、 an alert. This record shall be available for site review and audit. 2.2.3 Checking Prior to Saving PROTOCOLS and Audit Capability When a PROTOCOL is saved, the system shall display an alert (see 2.2.4) on the operators console if the estimated CTDIvolor DLP exceeds the corresponding ALERT VALUE. Th
33、e system shall be able to generate a list of ALERT VALUES. If any ALERT VALUE has not been set, the list will indicate this status. The system shall generate the list on request of the user. 2.2.4 Dose Alert Format The alert shall include at least three elements: a title, a body, and operator intera
34、ctions (including a field to enter diagnostic reason(s). The title of the alert shall be the text in the following box: DOSE ALERT A dose alert value will be exceeded! The body of the alert message shall identify the ALERT VALUE(S) that would be exceeded, the corresponding estimated dose value(s), a
35、nd may provide additional information for clarity. The interactions shall allow the operator to: (1) Enter diagnostic reason (optional) and enter the users name and password (if so configured) then confirm to proceed, or (2) Go back and adjust SCANNING PARAMETERS Copyright 2010 by the National Elect
36、rical Manufacturers Association. XR 25-2010 Page 6 ANNEX A (Informative) This example does not intend to represent any particular scanner model or brand of equipment and is intended only to assist the reader interpreting the terms used throughout this document. Consider a typical CT procedure with c
37、ontrast administration. It typically consists of four parts: Part 1: Scan projection radiograph, to define the SCAN location Part 2: Bolus Locatoraxial SCAN to define slice of patient to track Part 3: TrackingMultiple axial SCANS, monitoring the Bolus Locator slice after contrast has been administer
38、ed Part 4: Helical scanSCAN of patient, with contrast in the bloodstream Each of the above parts (1, 2, 3, 4) are separate PROTOCOL ELEMENTS. PROTOCOL ELEMENTS have their own SCAN PARAMETERS such as kVp, mA, rotation time, etc. PROTOCOL ELEMENT GROUP is defined by the Confirm/Go/Load software button
39、: Part 1 above is a PROTOCOL ELEMENT GROUP Part 2 above is a PROTOCOL ELEMENT GROUP Parts 3 and 4 above together form a PROTOCOL ELEMENT GROUP NoteNOTIFICATION VALUE for Part 1 above is not required by this standard. PROTOCOL is associated with a diagnostic task, e.g., tri-phased liver, head with/wi
40、thout contrast. All four of the PROTOCOL ELEMENTS above together make up a PROTOCOL. EXAMINATION is associated with a patient; e.g., trauma examination consisting of head and pelvis protocols. In this example, the PROTOCOL also represents the complete EXAMINATION. Parts 1 and 2 are each initiated by
41、 the technologist, by selecting “Confirm/Go/Load” on the user interface, and then pressing the “X-ray on” button. Part 3 is initiated by a “Confirm/Go/Load” on the user interface, and then pressing the “X-ray on” button or in conjunction with the Contrast hookup. Part 4 is automatically initiated (n
42、o need for “Confirm/Go/Load”) by the tracking scan, when the contrast is detected in the Bolus Locator slice. The dose NOTIFICATION VALUES and ALERT VALUES are checked each time “Confirm/Go/Load” is pressed. The key issue for comparisons is the combination of selecting “Confirm/Go/Load” on the user
43、interface, and then pressing the “X-ray on” button. In our simple example listed above, Part 2 will be compared to its individual NOTIFICATION VALUE. Parts 3 and 4 together comprise a single PROTOCOL ELEMENT GROUP. This is because of the automatic transition between parts 3 and 4. Upon pressing “Con
44、firm/Go/Load,” the system will compare the dose index for the Part 3 tracking scans against the corresponding NOTIFICATION VALUE. Additionally, the system will compare the dose index for Part 4, the helical scan, with the corresponding Copyright 2010 by the National Electrical Manufacturers Associat
45、ion. XR 25-2010 Page 7 NOTIFICATION VALUE. Finally, the system will compare the accumulated dose index (Part 2 already acquired and estimates for Parts 3 and 4) against the ALERT VALUE. Copyright 2010 by the National Electrical Manufacturers Association. NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 1300 NORTH 17TH STREET, SUITE 900 ROSSLYN. VA 22209www.NEMA.orgTO ORDER ADDITIONAL NEMA STANDARDS VISITWWW.GLOBAL.IHS.COM OR CALL 1-800-854-7179/1-303-397-79565612_0514TB
