Affiliations: Department of Mechanical Engineering, National Taipei
University of Technology, Taipei, Taiwan | Shin Kong Wu Ho-Su Memorial Hospital, Taipei,
Taiwan
Note: [] Corresponding author: Der-Chi Tien, Department of Mechanical
Engineering, National Taipei University of Technology, No. 1, Sec. 3,
Chung-Hsiao E. Rd. Taipei 10608, Taiwan. Tel.: +886 2 2771 2171 ext. 2140;
Fax: +886 2 2731 7191; E-mail: [email protected]; [email protected]
Abstract: Using the reverse motion of the treatment couch, this study offset
the organ displacement generated by respiratory motion to solve the current
clinical problem of increasing field sizes and safety margin expansions. This
study used the self-designed simulated respiratory system (SRS) coupled with
radiochromic EBT film to verify the self-developed respiratory compensation
system. Pressure signals were generated from SRS to simulate abdomen movements
during respiratory motion. The respiratory compensation system takes the phase
of the pressure signals as the respiratory motion phase and adjusts the
pressure signal gain to make the compensation signal amplitude close to the
displacement of the target region. A linear accelerator is used to irradiate a
300 cGy dose on the EBT film. The experimental results suggested that the
average dose percentage in the target region for the sine-wave amplitudes of 5,
10 and 15 mm with compensation improved by 6.9 ∼ 20.3%
over the cases without compensation. The 80% isodose area with compensation
improved by 22.8 ∼ 77.2% over the cases without
compensation. The average dose percentage in the target region with
compensation for respiratory motion distances of 5, 10 and 15 mm improved by
10.3 ∼ 18.7%. The 80% isodose area improved by 22.4
∼ 55.1% after compensation. The average dose percentage of the
compensated target region indicates that the proposed respiratory compensation
system could improve the issue of the inability to constantly irradiate the
target region caused by respiratory motion.
Keywords: Real-time tracking, compensated respiratory motion, GafChromic film
