Effects of respiratory phase and phantom position on uniformity of 4D-CT image(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2020年第1期
- Page:
- 65-68
- Research Field:
- 医学影像物理
- Publishing date:
Info
- Title:
- Effects of respiratory phase and phantom position on uniformity of 4D-CT image
- Author(s):
- SHI Feiyue1; 2; QIN Wei1; CHEN Fei1; ZHAO Huanyu1; JIN Xun3
- 1. Radiation Therapy Center, Nanjing First Hospital, Nanjing Medical University, Nanjing 210006, China; 2. Center of Medical Physics, Nanjing Medical University, Nanjing 210029, China; 3. the Second Clinical Medical College, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Keywords:
- Keywords: four-dimensional computed tomography; image uniformity; respiratory phase; phantom position
- PACS:
- R811.1；R318
- DOI:
- DOI:10.3969/j.issn.1005-202X.2020.01.013
- Abstract:
- Abstract: Objective To investigate the effects of respiratory phase and phantom position on the uniformity of four-dimensional computed tomography (4D-CT) images by analyzing the 4D-CT image of the CTP486 module in Catphan phantom. Methods Siemens Sensation Open CT simulator and Varian RPM system were used to obtain the 4D-CT images of CTP486 module in Catphan 504 phantom. The following 3 cases in which the phantom position was different were utilized to carry out this study. In Case A, the Catphan phantom was hung in the air; in Case T, a carbon fiber CT flat table was placed under the phantom; and in Case B+T, a carbon fiber immobilization baseplate and the CT flat table were placed under the phantom. Three measurements were implemented for each case. DoseLab radiotherapy verification software was used to analyze the 4D-CT images, and the image uniformity (U values) were obtained. Ten series of CT were reconstructed for 10 respiratory phases (0%, 10%,[ ?], 90%) for each 4D-CT measurement. Statistical analysis and comparative study were conducted on U values. Results All the U values of 4D-CT were smaller than 5 HU. For each case, 30 U values were obtained. The U values in Case A, Case T and Case B+T were (1.44±0.79), (1.91±0.91) and (1.99±0.77) HU, respectively. The numbers of times and proportions of the occurrence of 4 peripheral regions of interest which were corresponding to U values were analyzed. There were 13 ROI 22 (9 o’clock position) in case T, with a proportion of 43.33%, and 13 ROI 23 (12 o’clock position) in Case B+T, with a proportion of 43.33%. Conclusion The uniformity of 4D-CT images meets the requirements. The uniformity values of 4D-CT images for different respiratory phases are different. The phantom position has certain effects on the uniformity of 4D-CT images, and the existence of carbon fiber CT flat table and immobilization baseplate reduces the uniformity of 4D-CT images.
Last Update: 2020-01-14