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Recently, dynamic chest radiography using a flat panel detector (FPD) system with a large field of view was introduced for clinical use. This technique can provide sequential chest radiographs with high temporal resolution during respiration (17), and the ANA 12 Supplier dose is much lower than that of CT. Also, whereas CT and MRI are performed in the supine or prone position, dynamic chest radiology can be performed in a standing or sitting position, which is physiologically relevant. To the best of our knowledge, no detailed study has analyzed diaphragmatic motion during tidal breathing by using dynamic chest radiography.
The purpose of this study was to evaluate diaphragmatic motion during tidal breathing in a standing position in a health screening center cohort using dynamic chest radiography in association with participants\' demographic characteristics.
Materials and Methods
This cross-sectional study was approved by the institutional review board, and all the participants provided written informed consent. From May 2013 to February 2014, consecutive 220 individuals who visited the health screening of our hospital and met the following inclusion criteria for the study were recruited: age greater than 20 years, scheduled for conventional chest radiography, and underwent pulmonary function test. Patients with any of the following criteria were excluded: pregnant (n = 0), potentially pregnant or lactating (n = 0), refused to provide informed consent (n = 22), had incomplete datasets of dynamic chest radiography (n = 3), had incomplete datasets of pulmonary function tests (n = 1), could not follow tidal breathing instructions (eg, holding breath or taking a deep breath) (n = 18), or their diaphragmatic motion could not be analyzed by the software described next (n = 4). Thus, a total of 172 participants (103 men, 69 women; mean age 56.3 ± 9.8 years; age range 36–85 years) were finally included in the analysis ( Fig 1). The data from 47 participants of this study population were analyzed in a different study (under review). The heights and weights of the participants were measured, and the body mass index (BMI, weight in kilograms divided by height squared in meters) was calculated.
Figure 1. Flow diagram of the study population.Figure optionsDownload full-size imageDownload high-quality image (83 K)Download as PowerPoint slide
Imaging Protocol of Dynamic Chest Radiology (“Dynamic X-Ray Phrenicography”)
Posteroanterior dynamic chest radiography (“dynamic X-ray phrenicography”) was performed using a prototype system (Konica Minolta, Inc., Tokyo, Japan) composed of an FPD (PaxScan 4030CB, Varian Medical Systems, Inc., Salt Lake City, UT, USA) and a pulsed X-ray generator (DHF-155HII with Cineradiography option, Hitachi Medical Corporation, Tokyo, Japan). All participants were scanned in the standing position and instructed to breathe normally in a relaxed way without deep inspiration or expiration (tidal breathing). The exposure conditions were as follows: tube voltage, 100 kV; tube current, 50 mA; pulse duration of pulsed X-ray, 1.6 ms; source-to-image distance, 2 m; additional filter, 0.5 mm Al + 0.1 mm Cu. The additional filter was used to filter out soft X-rays. The exposure time was approximately 10–15 seconds. The pixel size was 388 × 388 µm, the matrix size was 1024 × 768, and the overall image area was 40 × 30 cm. The gray-level range of the images was 16,384 (14 bits), and the signal intensity was proportional to the incident exposure of the X-ray detector. The dynamic image data, captured at 15 frames/s, were synchronized with