Reproducibility of organ position using voluntary breath hold method with spirometer during extracranial stereotactic radiotherapy

Kimura, Takeshi; Hirokawa, Y; Murakami, Yukio; Tsujimura, M; Ohishi, Yoshiaki; Nakashima, Takeo; Yamada, Katsufumi; Ohno, Yoshimi; Kenjo, Masahiko; Kaneyasu, Yuuko; Ito, Kinro

doi:10.1016/s0360-3016(03)01386-5

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“…Attempts to eliminate or minimize tumor motion during diagnostic and treatment procedures through gating techniques have received much attention in recent years. These approaches take the form of physical immobilization of the tumor through either voluntary [4][5][6][7][8] or forced [9][10][11][12][13][14][15][16] breathing control or irradiation during a predetermined phase of motion. [17][18][19][20] Such control methods require the implementation of gating techniques not widely available in clinical environments.…”

Section: Introductionmentioning

confidence: 99%

The impact of tumor motion upon CT image integrity and target delineation

Gagne

Robinson²

2004

Medical Physics

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Accurate planning target volume delineation is vital to the success of conformal radiation techniques such as standard three-dimensional conformal radiotherapy and intensity modulated radiation therapy. With the exception of breath-hold schemes, all current approaches acquire images while the tumor is nonstationary and, as such, are subject to the presence of motion artifacts. In lung cancer sites where tumor mobility can be significant, the detrimental effect of these motion-induced distortions on image quality and subsequently target volume delineation cannot be ignored in the pursuit of improved treatment outcomes. To investigate the fundamental nature and functional dependence of computed tomography (CT) artifacts associated with lung tumor motion, and the implications for tumor delineation, a filtered backprojection algorithm was developed in MATLAB to generate transverse CT simulation images. In addition, a three-dimensional phantom capable of mimicking the essential motions of lung tumors was constructed for experimental verification. Results show that the spatial extent of a mobile object is distorted from its true shape and location and does not accurately reflect the volume occupied during the extent of motion captured. The presence of motion also negatively impacts image intensity (density) integrity rendering accurate volume delineation highly problematic and calling into question the use of such data in CT-based heterogeneity correction algorithms for dosimetric calculation.

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