Premium
TU‐C‐303A‐06: Quiet Respiration Breathing Motion Model Parameters for Free‐Breathing Patients
Author(s) -
Zhao T,
Lu W,
Bradley J,
Parikh P,
Hubenschmidt J,
Low D
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3182343
Subject(s) - breathing , exhalation , lung , medicine , lung volumes , position (finance) , nuclear medicine , radiology , anatomy , finance , economics
Purpose : To determine the quiet respiration breathing motion model parameters for lung cancer and non‐lung cancer patients. Method and Materials : 49 free‐breathing patient 4DCT image data sets (25 scans, ciné mode) were collected with simultaneous quantitative spirometry. A cross‐correlation registration technique was employed to track the lung tissue motion between scans. The registration results were fed back to a lung‐motion model: x = x 0 + α ν + β f , where x is the position of a piece of tissue located at reference position x 0 . α is a parameter which characterizes the motion due to local air filling (motion as a function of tidal volume) and β is the parameter that accounts for the motion due to the imbalance of dynamical stress distributions during inspiration and exhalation which cause lung motion hysteresis (motion as a function of airflow). The parameters α and β together provide a quantitative characterization of breathing motion that inherently includes the complex hysteresis interplay. The α and β distributions were examined for each patient to determine overall general patterns and intra‐patient pattern variations. Results : For 44 patients, the greatest value of | α | was observed in the inferior and posterior lungs. In three patients, | α | reached its maximum in the anterior lung, while for two patients; | α | was greatest in the lateral lung. The hysteresis motion β had greater variability, but for the majority of patients, | β | was largest in the lateral lungs. Conclusion : This is the first report of the 3‐dimensional breathing motion model parameter for a large cohort of patients. The overall α and β maps varied smoothly as expected. The majority of patients exhibited consistent α maps, and the β maps showed greater intra‐patient variability. The motion parameter intra‐patient variability will inform our need for custom radiation therapy motion models. This work supported in part by NIHR01CA096679 and NIHR01CA116712