Use of a speckle reduction technique to improve the reconstruction image quality of CCD-based optical computed tomography scanner

Chang, You-Soon

doi:10.1016/j.nima.2014.12.112

Cited by 5 publications

(2 citation statements)

References 16 publications

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“…We developed the proposed charge coupled device (CCD)-based parallel-beam optical-CT scanner (CT-s2) shown in Fig 1 [15,23]. The CT-s2 was used as dose readout tool after the polymer gel phantom was irradiated.…”

Section: Methodsmentioning

confidence: 99%

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Three-dimensional dose comparison of flattening filter (FF) and flattening filter-free (FFF) radiation therapy by using NIPAM gel dosimetry

et al. 2019

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Intensity-modulated radiotherapy and volumetric modulated arc therapy are modern radiation therapy technologies that can create the desired dose distribution by multileaf collimator movement and dose-rate control. However, the homogeneous dose delivery of small-field irradiation techniques shows disagreement with that of treatment planning system. The removal of the flattening filter by flattening filter free (FFF) beam irradiation increases dose conformity and further reduces treatment delivery time in radiosurgery. This study aims to investigate the dose distribution of FFF and flattened beams for small-field irradiation by using the 3D gel dosimeter. The N -isopropylacrylamide (NIPAM) polymer gel dosimeter was employed to record the 3D dose distribution. In addition, flattened and FFF beams were compared using the gamma evaluation technique. The use of an FFF accelerator resulted in excellent radiation treatments with short delivery times and low doses to normal tissues and organs. Results also showed that the passing rate increased with the decrease of field size (30 × 30, 20 × 20, and 10 × 10 mm 2 ) at post-irradiation times of 24, 48, 72, and 96 h. The passing rates for each field size were retained at the same level when gamma criteria, namely, distance-to-agreement (DTA) = 3 mm/dose difference (DD) = 3%, were used. Nevertheless, the passing rates for each field size decreased slowly after 48 h when DTA = 2 mm/DD = 2%. The Wilcoxon signed-rank test was used to determine statistical difference with a significant level of p < 0.05. The passing rates of flattened and FFF beams showed no significant difference. The edge enhancement effect in the flattened beam was more evident than in the FFF beam. The 3D NIPAM gel dosimeter can be used for dose verification of small field for radiation therapy with high dose rate.

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Section: Methodsmentioning

confidence: 99%

“…Totally, 360 projection images were acquired by the CCD camera. Then, the image reconstruction was performed using a filtered back-projection algorithm with our proposed program written in MATLAB [15,23–25].…”

Section: Methodsmentioning

confidence: 99%