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Quantification of the Probability Density Function Obtained From Respiratory Motions During 4DCT Simulations
M Sasaki1*, M Nakamura2 , Y Tsuruta1 , S Yano1 , M Nakata1 , K Higashimura1 , T Mizowaki2 , (1) Kyoto University Hospital, Kyoto, Kyoto, (2) Kyoto University, Graduate School of Medicine, Kyoto, Kyoto
Presentations
TU-C3-GePD-J(B)-2 (Tuesday, August 1, 2017) 10:30 AM - 11:00 AM Room: Joint Imaging-Therapy ePoster Lounge - B
Purpose: To quantify the probability density function (PDF) obtained from respiratory motions during 4DCT simulations.
Methods: Between January 2015 and February 2016, 236 consecutive respiratory patterns (120 chest diseases and 116 abdominal diseases) obtained during 4DCT simulations were analyzed. Scan time of 4DCT was longer than 120 seconds. The respiratory motions were sampled at 30 Hz using the real-time position management (Varian Medical Systems, Palo Alto, CA, USA). Each respiratory pattern was categorized into the following three groups; (1) the entire scan time (186.7±32.2 seconds for chest diseases and 195.6±50.5 seconds for abdominal diseases), (2) the first 60 sec (60 sec) and (3) the first 120 sec (120 sec). Data were standardized with the mean position of respiratory cycles for each duration. The standardized data were assigned to the bin of mean-/+kSD (-5≤k≤5). Positive k values indicate that the respiratory positions were dwelled near exhalation phase. Kurtosis and skewness were calculated to quantify the PDF. The statistical difference in kurtosis and skewness between elapsed times and between disease types was tested using Tukey’s test and unpaired t-test, respectively. Statistical significance was set at p < 0.01.
Results: The peak of PDF (46.0% on average) was exhibited at the bin of mean+1SD. The kurtosis for the entire scan time, 60 sec and 120 sec was 0.56±2.86, 0.12±2.49 and 0.32±2.67, respectively. The skewness for the entire scan time, 60 sec and 120 sec was -0.86±0.52, -0.81±0.54, and -0.83±0.52, respectively. No significant difference was observed regarding both the kurtosis and skewness. There was no significant difference in the kurtosis and skewness between chest and abdominal diseases.
Conclusion: The PDF obtained from the respiratory motions was mostly deviated from the mean position to the exhalation phase. An elapsed time and a disease type provided no significant difference in the PDF.
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