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To propose adding index of achievement (IOA) to IMRT QA process
Kim, Dong-Su,Kim, Siyong,Kang, Seong-Hee,Kim, Tae-Ho,Park, So-Hyun,Kim, Kyeong-Hyeon,Cho, Min-Seok,Shin, Dong-Seok,Noh, Yu-Yun,Chung, Jin-Beom,Suh, Tae Suk BioMed Central 2018 Radiation oncology Vol.13 No.-
<P><B>Background</B></P><P>In intensity modulated radiation therapy (IMRT) quality assurance (QA), evaluation of QA result using a pass/non-pass strategy under an acceptance criterion often suffers from lack of information on how good the plan is in absolute manner. In this study, we suggested adding an index system, previously developed for dose painting technique, to current IMRT QA process for better understanding of QA result.</P><P><B>Methods</B></P><P>The index system consists of three indices, index of achievement (IOA), index of hotness (IOH) and index of coldness (IOC). As indicated by its name, IOA does measure the level of agreement. IOH and IOC, on the other hand, measure the magnitude of overdose and underdose, respectively. A systematic analysis was performed with three 1-dimensional hypothetical dose distributions to investigate the characteristics of the index system. The feasibility of the system was also assessed with clinical volumetric modulated arc therapy (VMAT) QA cases from 8 head & neck and 5 prostate patients. In both simulation studies, certain amount of errors was intentionally induced to each dose distribution. Furthermore, we applied the proposed system to compare calculated with actual measured data for a total of 60 patients (30 head & neck and 30 prostate cases). QA analysis was made using both the index system and gamma method, and results were compared.</P><P><B>Results</B></P><P>While the gamma evaluation showed limited sensitivity in evaluating QA result depending on the level of tolerance criteria used, the proposed indices tended to better distinguish plans in terms of the amount of errors. Hotness and coldness of prescribed dose in the plan could be evaluated quantitatively by the indices.</P><P><B>Conclusions</B></P><P>The proposed index system provides information with which IMRT QA result would be better evaluated, especially when gamma pass rates are identical or similar among multiple plans. In addition, the independency of the index system on acceptance criteria would help making clear communications among readers of published articles and researchers in multi-institutional studies.</P>
A respiratory-guided 4D digital tomosynthesis
Kim, Dong-Su,Lee, Seungwan,Kim, Tae-Ho,Kang, Seong-Hee,Kim, Kyeong-Hyeon,Shin, Dong-Seok,Kim, Siyong,Suh, Tae Suk IOP 2018 Physics in medicine & biology Vol.63 No.24
<P>The aim of this research was to introduce and evaluate a respiratory-guided slow gantry rotation 4D digital tomosynthesis (DTS). For each of ten volunteers, two breathing patterns were obtained for 3 min, one under free breathing conditions and the other with visual respiratory-guidance using an in-house developed respiratory monitoring system based on pressure sensing. Visual guidance was performed using a 4 s cycle sine wave with an amplitude corresponding to the average of end-inhalation peaks and end-exhalation valleys from the free-breathing pattern. The scan range was 40 degrees for each simulation, and the frame rate and gantry rotation speed were determined so that one projection per phase should be included. Both acquisition time and the number of total projections to be acquired (NPA) were calculated. Applying the obtained respiration pattern and the corresponding sequence, virtual projections were acquired under a typical geometry of Varian on-board imager for two virtual phantoms, modified Shepp–Logan (mSL) and extended cardiac-torso (XCAT). For the XCAT, two different orientations were considered, anterior–posterior (i.e. coronal) and left-right (i.e. sagittal). Projections were sorted to ten phases and image reconstruction was made using a modified filtered back-projection. Reconstructed images were compared with the planned breathing data (i.e. ideal situation) by structural similarity index (SSIM) and normalized root-mean-square error (NRMSE). For each case, simulation with guidance (SwG) showed motion-related artefact reduction compared to that under free-breathing (SuFB). SwG required less NPA but provided slightly higher SSIM and lower NRMSE values in all phantom images than SuFB did. In addition, the distribution of projections per phase was more regular in SwG. Through the proposed respiratory-guided 4D DTS, it is possible to reduce imaging dose while improving image quality. (Institutional Review Board approval: MC17DESI0086)</P>
Prevalence of Brachyspira hyodysenteriae on selected swine farms in Gyeongbuk province by PCR
( Dong Kyun Suh ),( Yun Jeong Do ),( Jong Su Ha ),( Kyeong Hyeon Lee ),( Yoo Jung Cho ),( Dong Jun Song ),( Chun Sik Lee ),( Young Chan Bae ),( Won Pil Choi ),( Keun Woo Lee ),( Jae Chan Song ) 한국가축위생학회 2001 韓國家畜衛生學會誌 Vol.24 No.4
The purpose of this study is to determine the prevalence of Brachyspira hyodysenteriae from 43 swine farms with diarrhea or a history of diarrhea in Gyeongbuk province by PCR. The overall herd prevalence of B hyodysenteriae was 37.2%(16/43), and the average prevalence of B hyodysenteriae among all sampled pigs was 10.8%(50/462). Positive herds for B hyodysenteriae were distributed throughout Gyeongbuk province from 14.3~50%. Herd size had A effect on the frequency of B hyodysenteriae. The frequency of B hyodysenteriae in herds with less than 1,000 pigs was 47.4%, That of herds between 1,001 and 2,000 pigs was 41.7%. Also, the frequency of B hyodysenteriae in herds with more than 2,000 pigs was 16.7%.