title: Respiratory monitoring with an acceleration sensor.
abstract: Respiratory gating radiotherapy is used to irradiate a local area and to reduce normal tissue toxicity. There are certain methods for the detection of tumor motions, for example, using internal markers or an external respiration signal. However, because some of these respiratory monitoring systems require special or expensive equipment, respiratory monitoring can usually be performed only in limited facilities. In this study, the feasibility of using an acceleration sensor for respiratory monitoring was evaluated. The respiratory motion was represented by means of a platform and measured five times with the iPod touch® at 3, 4 and 5 s periods of five breathing cycles. For these three periods of the reference waveform, the absolute means ± standard deviation (SD) of displacement were 0.45 ± 0.34 mm, 0.33 ± 0.24 mm and 0.31 ± 0.23 mm, respectively. On the other hand, the corresponding absolute means ± SD for the periods were 0.04 ± 0.09 s, 0.04 ± 0.02 s and 0.06 ± 0.04 s. The accuracy of respiratory monitoring using the acceleration sensor was satisfactory in terms of the absolute means ± SD. Using the iPod touch® for respiratory monitoring does not need special equipment and makes respiratory monitoring easier. For these reasons, this system is a viable alternative to other respiratory monitoring systems.
authors: Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Yamadaoka 1-7, Suita-shi, Osaka 565-0871, Japan.
authors: Tomohiro
authors: T
authors: Ono
authors: Hideki
authors: H
authors: Takegawa
authors: Tatsuya
authors: T
authors: Ageishi
authors: Masaaki
authors: M
authors: Takashina
authors: Hodaka
authors: H
authors: Numasaki
authors: Masao
authors: M
authors: Matsumoto
authors: Teruki
authors: T
authors: Teshima
mesh_terms: D000054:Acceleration; D015374:Biosensing Techniques / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D008991:Monitoring, Physiologic; D009038:Motion; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012119:Respiration; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D013997:Time Factors