Evaluation of the combined use of two different respiratory monitoring systems for 4D CT simulation and gated treatment

Abstract

PurposeTwo different respiratory monitoring systems (Varian's Real‐Time Position Management (RPM) System and Siemens’ ANZAI belt Respiratory Gating System) are compared in the context of respiratory signals and 4D CT images that are accordingly reconstructed. This study aims to evaluate the feasibility of combined use of RPM and ANZAI systems for 4DCT simulation and gated radiotherapy treatment, respectively.MethodsThe RPM infrared reflecting marker and the ANZAI belt pressure sensor were both placed on the patient's abdomen during 4DCT scans. The respiratory signal collected by the two systems was synchronized. Fifteen patients were enrolled for respiratory signal collection and analysis. The discrepancies between the RPM and ANZAI traces can be characterized by phase shift and shape distortion. To reveal the impact of the changes in respiratory signals on 4D images, two sets of 4D images based on the same patient's raw data were reconstructed using the RPM and ANZAI data for phase sorting, respectively. The volume of whole lung and the position of diaphragm apex were measured and compared for each respiratory phase.ResultsThe mean phase shift was measured as 0.2 ± 0.1 s averaged over 15 patients. The shape of the breathing trace was found to be in disagreement. For all the patients, the ANZAI trace had a steeper falloff in exhalation than RPM. The inhalation curve, however, was matched for nine patients, steeper in ANZAI for five patients and steeper in RPM for one patient. For 4D image comparison, the difference in whole‐lung volume was about −4% to +4% and the difference in diaphragm position was about −5 mm to +4 mm, compared in each individual phase and averaged over seven patients.ConclusionsCombined use of one system for 4D CT simulation and the other for gated treatment should be avoided as the resultant gating window would not fully match with each other due to the remarkable discrepancy in breathing traces acquired by the two different surrogate systems.

Stability and Reliability of Enhanced External-Internal Motion Correlation via Dynamic Phase-Shift Corrections Over 30-min Timeframe for Respiratory-Gated Radiotherapy

“…In fact, a phase shift between the RPM and bellows was previously reported. 37 When it is placed just inferior to the xiphoid process of the sternum, the bellows encircles the lateral and posterior ribs and therefore senses the movements of both the diaphragm and the intercostal muscles. By contrast, the internal navigator senses only the motion of the diaphragm.…”

Feasibility of using a novel automatic cardiac segmentation algorithm in the clinical routine of lung cancer patients

“…ANZAI belt systems (Anzai Medical Co. Ltd., Tokyo, Japan) were wrapped around the abdomen during the image acquisition. A 3D free breathing CT scan and subsequent 4D-CT scan, both with a slice thickness of 1.5 mm, were acquired with a Philips Big Bore CT scanner (Philips, Eindhoven, The Netherlands) with respiratory gating using the AZ-733VI system (Anzai Medical Co. Ltd, Tokyo, Japan) to measure the respiratory motion [23]. The 3D-CT and 4D-CT image sets (binned into ten breathing phases: 0% -90%) were exported to MIM Maestro (MIM Software, Cleveland, OH, USA) for delineation by one of four experienced radiation oncologists, who contoured the heart in axial slices.…”

Investigation of internal target volumes using device and deviceless four-dimensional respiratory monitoring systems for moving targets in four-dimensional computed tomography acquisition

“…There are several studies evaluating the technical aspects of various gating techniques. [ 17 18 19 ] These studies were mainly limited to the evaluation of technical factors, namely time resolution, signal amplitude, noise, signal-to-noise ratio, signal linearity, and trigger compatibility. [ 17 ] For example, when the Siemens CT with external surrogate system (Anzai Respiratory Gating System, Anzai Medical Co., Ltd, Japan) was simultaneously used with optical camera system on a dynamic phantom, tumor trajectories had discrepancies up to 9.7 mm among them.…”

“…[ 18 ] Furthermore, simultaneous use of Varian's Real-Time Position Management and Anzai Respiratory Gating System resulted in mismatch of gating window with each other due to the discrepancy in breathing traces acquired by the two different surrogate systems. [ 19 ] In the absence of a thorough investigation to study the influence of these technical factors on the reconstructed target volumes with statistical inferences, a well-designed, controlled study, directly comparing DB method and DL method with the ground truth volume for 4D sorting, is necessary. The current studies on 4DCT do not include the controlled variations in the breathing pattern including the target motion in all the three directions.…”

“…The current studies on 4DCT do not include the controlled variations in the breathing pattern including the target motion in all the three directions. [ 17 18 19 20 13 ] Hence, in this study, we assessed the influence of target motion on the reconstructed target size for DB method (Anzai Respiratory Gating System, Anzai Medical Co., Ltd, Japan) and DL method (Smart Deviceless 4D system by GE Medical Systems, Chicago, USA) in a controlled phantom experiment with the programmed target motion. The volumetric changes in reconstructed ITVs from the AveIP images using DB method with DL method for moving target with the increasing target motion in anterio-posterior (A-P), left-right (L-R), and inferior-superior (S-I) directions were assessed.…”