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Aperture maneuver with compelled breath (AMC) for moving tumors: A feasibility study with a moving phantom
Author(s) -
Suh Y.,
Yi B.,
Ahn S.,
Kim J.,
Lee S.,
Shin S.,
Shin S.,
Choi E.
Publication year - 2004
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1650565
Subject(s) - imaging phantom , multileaf collimator , dosimetry , breathing , aperture (computer memory) , radiation therapy , exhalation , beam (structure) , computer science , nuclear medicine , physics , biomedical engineering , linear particle accelerator , optics , medicine , acoustics , radiology , anatomy
Respiration causes target motion, which is known to be one of the technical bottlenecks in radiotherapy, especially for stereotactic radio‐surgery and intensity modulated radiotherapy (IMRT). To overcome this problem, aperture maneuver with compelled breath (AMC) has been developed. In order to simulate compelled respiratory motion, a moving phantom using a ventilator was designed. As the air flow was forced to the bellows, which simulates the lungs, by a ventilator, a film connected to the ventilator moved like the respiratory target motion. A software was developed to transfer multileaf collimator motion from breathless to actual periodic breathing conditions. Static fields as well as step‐and‐shoot IMRT fields were modified in accordance with moving shapes to follow the target position, using the software with the controlled breathing information. Film dosimetry for a small field and for IMRT fields with a moving phantom was performed. To evaluate clinical implementation, five healthy volunteers were tested to breathe through a ventilator, and all of them could adapt the compelled breath without any difficulties. Additive margins for a moving target with AMC were not larger than 3 mm for respiratory organ motions up to 18 mm, while those with the static beam were 9 mm. For IMRT fields, large discrepancies were present between a static target and a moving target with the static beam, while they coincided well with AMC. Clinical acceptable differences between the dose distributions from a static target with the static beam and from a moving target with AMC revealed that this technique could be applied clinically.