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KMID : 1164220210330010047
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Journal of Korean Society for Radiotherapeutic Technology
2021 Volume.33 No. 1 p.47 ~ p.54
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Evaluation of the usefulness of the method according to changes in patient breathing during chest 4D CT imaging
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Heo Sol
Shin Chung-Hun
Jeong Hyun-Sook
Yoo Soon-Mi
Kim Jeong-Mi
Yun In-Ha
Hong Seung-Mo
Back Geum-Mun
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Abstract
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Purpose : In order to evaluate the usefulness of clinical application of the Pause & Resume methods by comparing and analyzing the data stability and dose reduction effect when repeat scan assuming irregular breathing and using the Pause & Resume method during chest 4D CT using QuasarTM Phantom.
Materials and Methods : Using the QuasarTM Phantom, set the breathing rate per minute to 15 BPM and 7.5 BPM, and set the S15 point as an irregular breathing section, and then placed OSLD to this point and use the Pause & Resume method to measure the dose of S15. CTDIvol, DLP, and ALARA-CT were used for comparative analysis of radiation dose between Pause & Resume method and Repeat-scan. In order to evaluate the stability and usability of the data applying the Pause & Resume method, the captured images were sorted by Advanced Workstation Volume Share7 and then sent to EclipseTM, the diameter and volume were analyzed by forming a contour on the iron ball in the QuasarTM Phantom
Results : When using Pause & Resume, the dose of OSLD measurement increased by 1.97 times in the section of S15. As a result of image evaluation, the average value of all volumes measured with and without the Pause & Resume method at 15 BPM and 7.5 BPM was 15.2 cm3±0.5%.Allthemeasuredvaluesfor the radius of iron ball were 3.1 cm regardless of whether Pause & Resume method was used or not. In the case of using Pause & Resume, 33% decreased from the lowest DLP value and 38% decreased from the highest DLP value of repeat scan, and the effective dose also decreased 32.1% from the minimum value and 37.6% from the maximum value.
Conclusion: Irradiation dose was increased by Pause & Resume method because of the repeat scan on the S15 site where assuming irregular breathing occurred, However Pause & Resume method led to a significant reduction in dose on overall scan range. It also proved the usefulness of clinical application of the Pause & Resume method as a result of similar diameters and volumes of iron ball measurement.
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KEYWORD
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Quasar™ Phantom, DLP, Pause & Resume, OSLD, S15, 4D CT
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