The Journal of JASTRO
Online ISSN : 1881-9885
Print ISSN : 1040-9564
ISSN-L : 1881-9885
TIMING OF SYNCHRONIZATION IN INTERMITTENT IRRADIATION SYNCHRONIZED WITH RESPIRATORY MOTION
Toshifumi NAKAJIMAMasayuki NISHIOKAMasashi TSUMURAYasuto ONOYAMATomio FUJIOKAMakoto SAKURAITakuhito TADA
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1995 Volume 7 Issue 4 Pages 351-356

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Abstract
In order to reduce the increase in the irradiated volume caused by respiratory motion, a system which intermittently emits radiation synchronized with respiration was developed. A phantom of oscillating motion was made, and the effect of the motion on the penumbra of the dose profile was investigated by varying the distance of the motion and changing the timing of the synchronization. Irradiation was carried out by a 10-MV linear accelerator. Decreasing the irradiated time per motion cycle reduced the width of the penumbra. With a synchronized irradiation gated at end-of-inspiration or end-of-expiration, an intermittent irradiation ratio 47% kept the extension of the penumbra width to 2.2 times of the value measured in the phantom without motion when the motion distance was 4 cm. Investigation of the patients' diaphragmatic motion was done by reading the IBS (Image Brightness Stabilizer) circuit during fluoroscopic examination. A quiescent period was often observed at end-of-expiration. Synchronized irradiation gated at end-of-expiration was considered suitable for clinical application.
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© 1994 The Japanese Society for Therapeutic Radiology and Oncology
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