Using a local Dose Index Registry system to determine Notification Values for the MITA XR 25 (Dose Check) Standard in CT

Transcription

1 Using a local Dose Index Registry system to determine Notification Values for the MITA XR 25 (Dose Check) Standard in CT Poster No.: C-0913 Congress: ECR 2014 Type: Authors: Scientific Exhibit M. Shinozaki 1, T. Arai 1, Y. Muramatsu 2, T. Sasaki 1 ; 1 Tokyo/JP, 2 Chiba/JP Keywords: DOI: Quality assurance, Physics, CT, Radiation physics /ecr2014/C-0913 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 16

2 Aims and objectives Since a new technical standard for X-ray CT has been published by the National Electrical Manufacturers Association (NEMA), the alert value and notification value for the cumulative dose are configurable by operators of CT systems in conjunction with XR-25 (Dose check) standard. In this study, a decision method of the notification values for reducing the radiation dose was examined with dose index registry (DIR) system. Methods and materials An object is for 261 continuous days on August 1, 2012 to April 18, 2013.CT images were obtained with the Discovery CT 750HD (GE Healthcare) and dose indices were calculated with the DoseWatch DIR system. And an object is for 100 continuous days January 9, 2013 to April 18, SOMATOM Definition flash#siemens#and DoseWatch (GE Healthcare) DIR system. CT Dose Index (CTDI vol ) and Dose Length Product (DLP) were outputted from DIR system as comma-separated values (CSV) file format for the each examination protocol. All data were shown as a schematic boxplot with the statistics processing software. Images for this section: Page 2 of 16

3 Fig. 1: Disclosure of conflict of interest Page 3 of 16

4 Fig. 2: Details of the patients Page 4 of 16

5 Fig. 3: Typical protocol and scan parameter(750hd, Chest plain) Page 5 of 16

6 Fig. 4: Typical protocol and scan parameter(750hd, Chest-Pelvis 2phase) Page 6 of 16

7 Fig. 5: Typical protocol and scan parameter(definition flash, Chest plain) Page 7 of 16

8 Fig. 6: Typical protocol and scan parameter(definition flash, Chest-Pelvis 2phase) Page 8 of 16

9 Results Statistics analysis of the dose indices were conducted about all the protocols in a collection period. The result is shown about the Chest-plain and the Chest-pelvis 2phase which are two protocols which were the highest as for frequency in our facilities. Definition flash tends to be slightly high in a thing of dose indices. The main causes are that the Definition flash does not have iterative reconstruction units. Images for this section: Fig. 7: CTDI at Chest plain protocol (75oHD & Definition flash) Page 9 of 16

10 Fig. 8: DLP at Chest plain protocol (75oHD & Definition flash) Page 10 of 16

11 Fig. 9: CTDI at Chest-pelvis protocol 1st phase(75ohd & Definition flash) Page 11 of 16

12 Fig. 10: DLP at Chest-pelvis protocol 1st phase(75ohd & Definition flash) Page 12 of 16

13 Fig. 11: CTDI at Chest-pelvis protocol 2nd phase(75ohd & Definition flash) Page 13 of 16

14 Fig. 12: DLP at Chest-pelvis protocol 2nd phase(75ohd & Definition flash) Page 14 of 16

15 Conclusion Discussion Notification Value to recommend according to AAPM Dose Check Guidelines is higher than a value of published DRLs.As for this, a one-third of the American group gains too much weight, and the child (radiation sensitivity is higher than adults) requires a notice level (Notification Value) and a warning level (Alert value) that are different from special consideration for size smaller than them.japanese has a smaller body than Westerners generally.therefore it is difficult to just misappropriate a notice of AAPM. Notification Value sets it every protocol and scan parameter varies with performance of CT. It is thought whether investigation is needed in individual institutions (or CT). Furthermore, it is necessary to input different Notification Value by each CT because a tendency of the dose index is different in individual CT. We think the following things to be important on determining an initial value of Notification Value. 1. Being a safe side. 2. Take a comparison and consistency with DRLs. 3. The operative thing that becomes efficient of an attention awakening and the examination of the operator. These results indicated that the 75% tile of CTDI vol and DLP as an initial value provided to be safe and efficient for the CT examination and operation. Conclusion The initial value of Notification value in each protocol is taken as the 75% tile value got by statistics analysis. This concludes that it can aim at safe and efficient employment on dose management. However, it restricts setting up a high percent tile value by the self-foreword efforts for each institution based on accumulation and reappraisal of dose data, or does not deny it. A setup of Notification value is manually inputted for every protocol. A DIR system and CT equipment communicate mutually and a systems configuration which a setup of Notification value and feedback of statistical data can check and correct on CT console is desired. Page 15 of 16

16 Personal information References #Computed Tomography Dose Check (NEMA Standards Publication XR ) 2010/10 #AAPM Dose Check Guidelines version /4 #ICRP Publication 87 ICRP 30 (4), 2000 #Diagnostic reference levels in medical imaging: review and additional advice. ICRP 2001; 31(4): Page 16 of 16