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The Experiment and Simulation Study of Respiration on the Dose Distribution in Radiotherapy

  • Xiao Xu
  • Keqiang Wang
Conference paper
Part of the Advances in Intelligent and Soft Computing book series (AINSC, volume 145)

Abstract

Objective: To evaluate the influence of respiration on the radiation dose distribution in radiotherapy with matlab simulation and film dosimetry. Methods: Radiation of 50MU was delivered in a square, round, ellipse, dumb bell, or female shaped field to the films within a moving or static Respiration Motion Phantom respectively, the dose distributions for the two motion status were measured and compared. In order to further verify the impact of amplitude of respiration movement, the matlab simulation with movement amplitude of 0 cm, 0.5 cm, 1.0 cm, 1.5 cm, 2.0 cm, and 2.5cm were done respectively. The dose distributions in different status were measured and compared with film dosimetry. Iso-dose line comparison, NAT (Normalized Agreement Tests) and γ comparison were used for the comparison of dose distributions. Fs was used as an index to evaluate the differences of the areas that surrounded by iso-dose lines in different situations (FS90, FS50, FS25 delegates the ratio of the areas that surrounded by 90%, 50%, 25% iso-dose line in different situation respectively). Results: (1) For round field, the matlab simulation showed that S90 decreased as the increase of the movement. S90 was almost 0 when the amplitude became to half of the diameter of the field. S25 varied inversely. (2) The experiment showed that in horizontal movement situation compared with in static situation, the FS90 became smaller and the FS25 became larger. The more the displacement became larger, the more the FS90 and the FS25 deviate remarkable. In vertical movement situation, Fs changed significantly in square field and dumb bell shaped field while changed a little in the others. (3) γ and NAT comparison: In the horizontal movement situation, compared with in the static phantom, the P γ was <60% and the PNAT was <75% in every radiation field. In vertical movement situation, the P γ was less than 85% for all the square, round, dumb bell and female shaped fields. Conclusions: The respiration can impact on the dose distribution within the target volume in radiotherapy, leading to a smaller area of higher dose level and an expanded area of lower dose level. The influence will become more significant with larger movement of the target.

Keywords

Dose Distribution Static Situation Shaped Field High Dose Region Film Dosimetry 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag GmbH Berlin Heidelberg 2012

Authors and Affiliations

  1. 1.The General Hospital of Tianjin Medical UniversityTianjinChina

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