Respiratory Monitoring Device Research Articles

Reproducibility of The Abdominal and Chest Wall Position by Voluntary Breath-Hold Technique Using a Laser-Based Monitoring and Visual Feedback System

The voluntary breath-hold (BH) technique is a simple method to control the respiration-related motion of a tumor during irradiation. However, the abdominal and chest wall position may not be accurately reproduced using the BH technique. The purpose of this study was to examine whether visual feedback can reduce the fluctuation in wall motion during BH using a new respiratory monitoring device. We developed a laser-based BH monitoring and visual feedback system. For this study, five healthy volunteers were enrolled. The volunteers, practicing abdominal breathing, performed shallow end-expiration BH (SEBH), shallow end-inspiration BH (SIBH), and deep end-inspiration BH (DIBH) with or without visual feedback. The abdominal and chest wall positions were measured at 80-ms intervals during BHs. The fluctuation in the chest wall position was smaller than that of the abdominal wall position. The reproducibility of the wall position was improved by visual feedback. With a monitoring device, visual feedback reduced the mean deviation of the abdominal wall from 2.1 +/- 1.3 mm to 1.5 +/- 0.5 mm, 2.5 +/- 1.9 mm to 1.1 +/- 0.4 mm, and 6.6 +/- 2.4 mm to 2.6 +/- 1.4 mm in SEBH, SIBH, and DIBH, respectively. Volunteers can perform the BH maneuver in a highly reproducible fashion when informed about the position of the wall, although in the case of DIBH, the deviation in the wall position remained substantial.

Relation of external surface to internal tumor motion studied with cine CT

The accuracy of delivering gated-radiation therapy to lung tumors using an external respiratory surrogate relies on not only interfractional and intrafractional reproducibility, but also a strong correlation between external motion and internal tumor motion. The purpose of this work was to use the cine images acquired by four-dimensional computed tomography acquisition protocol to study the relation between external surface motion and internal tumor motion. The respiratory phase information of tumor motion and chest wall motion was measured on the cine images using a proposed region-of-interest (ROI) method and compared to measurement of an external respiratory monitoring device. On eight lung patient data sets, the phase shifts were measured between (1) the signal of a real-time positioning-management (RPM) respiratory monitoring device placed in the abdominal region and four surface locations on the chest wall, (2) the RPM signal in the abdominal region and tumor motions, and (3) chest wall surface motions and tumor motions. Respiratory waveforms measured at different surface locations during the same respiratory cycle often varied and had significant phase shifts. Seven of the 8 patients showed the abdominal motion leading chest wall motion. The best correlation (smallest phase shift) was found between the abdominal motion and the superior-inferior (S-I) tumor motion. A wide range of phase shifts was observed between external surface motion and tumor anterior-posterior (A-P)/lateral motion. The result supported the placement of the RPM block in the abdominal region and suggested that during a gated therapy utilizing the RPM system, it is necessary to place the RPM block at the same location as it is during treatment simulation in order to reduce potential errors introduced by the position of the RPM block. Correlations between external motions and lateral/A-P tumor motions were inconclusive due to a combination of patient selection and the limitation of the ROI method.

Method and device for analyzing respiratory sounds in horses

The invention provides a device and a method for recording respiratory sounds in exercising horses thereby enabling the user identify upper airway abnormalities and/or evaluate athletic potential by, e.g., measuring expiratory and/or inspiratory times during exercise under field and/or actual racing conditions. In particular, the invention provides a respiratory monitoring system or device in which a transducer or microphone is placed in direct contact with the skin of the subject animal overlying the skull, e.g., the frontal sinus or nasal turbinates and thereby enable recording and analysis of upper airway respiratory sound from the exercising animal. In one embodiment, the invention provides a device wherein the transducer or microphone is positioned or embedded within a gel pad or other suitable medium and the device placed in direct contact with the skin of the animal overlying, e.g., the skull, sinus or nasal turbinates of the horse The device of the invention provides an acoustic monitoring system capable of direct attachment to the head of a racing horse which produces an output signal that is not diluted, attenuated or otherwise corrupted by noises such as wind, hoof beats and/or treadmill noises.

A Newly Developed Simple and Accurate Respiratory Indicator Relative to Measurement of 2-Point Levels of Abdominal and Chest Walls: for Assurance of Patient Self-Judged Breath Holding Techniques for Irradiation of Lung Cancer with Small Internal Margin

Purpose/Objective: We have utilized the technique of patient self-breath-holding without respiratory monitoring devices for irradiation of lung cancer with small internal margin. However, some patients were not good at understanding and performing the self-breath-holding technique precisely. This study was designed to develop a simple and novel mode of respiratory monitor according to measurement of 2-point levels of abdominal and chest walls for the breath holding technique, and to evaluate its accuracy for the reproducibility of the tumor position.

A new irradiation system for lung cancer combining linear accelerator, computed tomography, patient self-breath-holding, and patient-directed beam-control without respiratory monitoring devices

Purpose To introduce and assess a new irradiation technique for lung cancer that utilizes a linear accelerator and computed tomography (CT) scanner combination, along with a novel switching mechanism, which enables patients to synchronize the duration of irradiation with self-breath-holding without respiratory monitoring devices. Methods and materials A newly developed treatment unit, a linear accelerator combined with a CT scanner (CT-linac), was used for irradiation. A novel switching mechanism, connected directly to the console of the linear accelerator, enabled the patient to control the radiation beam to correspond with the duration of self-breath-holding during a session determined by a radiation technologist. Twenty patients with lung cancer were enrolled in this study. All patients were instructed in the technique of breath-holding during the inspiration phase using visualization of respiratory motion through fluoroscopy as a teaching aid. CT scans under patients’ self-breath-holding were repeated three times, and differences in tumor position on CT images were measured. The reproducibility of tumor position was visually evaluated on electronic portal images (EPI). Results Mean maximum differences in tumor position under patients’ self-breath-holding were 2.2 mm in the cranial-caudal direction, 1.4 mm in the anterior-posterior direction, and 1.3 mm in the right-left direction. Switching of the radiation beam was delayed less than 0.1 s behind patient switching. EPIs were used to determine that reproducibility of tumor position was satisfactorily accurate. Conclusion The reproducibility of tumor position, during patient self-breath-holding synchronized with patient-initiated radiation and without a respiratory monitoring device, was sufficiently accurate. This novel irradiation technique for lung tumors using a combination CT-linac offers reduced PTV, sufficient reproducibility, and decreased duration of treatment.

A new irradiation system for lung cancer: patient’s self-breath-hold and self-switching radiation-beam on and off without any respiratory monitoring devices

Purpose: It is helpful to irradiate a lung tumor under a breath-hold for a reduction of planning target volume(PTV). To develop a simple and efficient breath-hold radiation technique for lung cancer, we made three purposes. 1) To compare the reproducibility of tumor-position under a breath-hold by a patient’s self-estimation with that under a breath-hold by a radiation technologist’s instruction. 2) To develop a switch which enable a patient to turn the radiation-beam on and off. 3) To evaluate the reproducibility of a tumor-position in the radiation field with a patient’s self-breath-hold and self-switching radiation-beam. Materials and Methods: Twenty patients with lung cancer were enrolled in this study. All patients were taught sufficiently how to hold the breath at a same inspiration phase with showing a fluoroscopy of respiratory motion before evaluation. CT images were obtained with 2mm-thickness in the vicinity of the tumor under a series of the breath-hold by a radiation technologist’s instruction and another series of the breath-hold by a patient’s self-estimation. CT was repeated three times with each breath-hold method. Differences of tumor position on CT images were measured in three dimensions with a CT analyzing menu. We have newly developed a switch which was connected directly to the console box of linac ( EXL-15DP; Mitsubishi Electric, Tokyo, Japan). It enables a patient to turn radiation beam on and off freely and repeatedly during a term designated by a radiation technologist. Ten real-time portal images were taken for each patient during irradiation under a patient’s self-breath-hold and self-switching radiation-beam, and the accuracy of reproducibility of the tumor position in the radiation field was visually evaluated. Results: The average of maximum differences of the tumor position in three series of 20 patients under the breath-hold by a radiation technologist’s instruction was 3.0 mm in cranio-caudal direction, 2.1mm in antero-posterior direction and 2.3mm in right-left direction. And that in three series under the breath-hold by a patient’s self-estimation was 2.3mm in cranio-caudal direction, 1.4mm in antero-posterior direction and 1.4mm in right-left direction, respectively. A standard deviation of these differences was larger in the method of breath-hold by a radiation technologist’s instruction than in the method of breath-hold by a patient’s self-estimation. And these differences were larger in tumors of lower lung field than upper lung field. There was statistically significant difference between two methods of breath-hold. The actual switching of the radiation beam was delayed less than 0.1 second behind the patient’s switching. All portal images of 20 patients had a visually sufficient accuracy of tumor position in the radiation field with a difference less than 3mm between a planned position and actual tumor positions. Conclusion: The reproducibility of tumor position under patient’s self breath-hold without any respiratory monitoring devices had a satisfactory accuracy with a difference of tumor position less than 3mm in all directions. The method of breath-hold by a patient’s self-estimation was more accurate than that by a radiation technologist’s instruction. Our newly developed switch which enabled patients to turn the radiation-beam on and off was useful with a good reproducibility under a breath-hold at patients’ pace. And it has an excellent time-efficiency because the irradiation starts at the initiation of patients’ breath-hold and continues irradiation as long as patients keep the breath-hold. This new irradiation system is simple (no need for a respiratory monitoring device) and useful for irradiation of lung cancer with reduced PTV and a sufficient reproducibility.

A new irradiation technique for lung cancer: Patient's self-breath-hold and self-switching radiation-beam on and off without any respiratory monitoring devices

A new irradiation technique for lung cancer: Patient's self-breath-hold and self-switching radiation-beam on and off without any respiratory monitoring devices