Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 68, Issue 2
Displaying 1-8 of 8 articles from this issue
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Opening Article
Original
  • Motion Analysis of Target during Stereotactic Radiotherapy of Lung Tumors Using Volumetric Modulated Arc Therapy
    Toshikazu Imae, Hiroyuki Shinohara, Kenji Ino, Yukari Okano, Katsutake ...
    2012 Volume 68 Issue 2 Pages 153-161
    Published: January 20, 2012
    Released on J-STAGE: March 01, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.2.153
    JOURNAL FREE ACCESS
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    Volumetric modulated arc therapy (VMAT) is a rotational intensity-modulated radiotherapy (IMRT) technique capable of acquiring projection images for cone-beam computed tomography (CBCT). Respiratory-correlated cone-beam computed tomography, namely 4D-CBCT, serves to assess the displacement of a tumor position between planning and treatment due to organ motion and respiration, and is important for more accurate radiation therapy. On the other hand, recently, a 320-detector row CT scanner, namely 4D-CT, has become available that allows axial volumetric scanning of a 16-cm-long range in a patient without table movement. The goal of our research is to establish a new method of verification during treatment in stereotactic body radiotherapy. In this study, we compare the movement of the tumor between “before treatment” using 4D-CT and “in treatment” using 4D-CBCT. Three patients (55–68 years of age) with lung tumors underwent CT scans for radiotherapy planning using 4D-CT scans to analyze the movement of the tumor before treatment. The patients were treated by VMAT while acquiring projection images. 4D-CBCT datasets were reconstructed from the projection images using in-house programs. The tumor positions in 4D-CT and 4D-CBCT were detected and the movement of the tumor between “before treatment” and “in treatment” was similar. The movement of the tumors during treatment was predictable from 4D-CT before treatment. Furthermore, 4D-CBCT clarified the tumor position during treatment and could reevaluate the actual tumor position and dose distribution. We have successfully shown the movement of the tumor between “before treatment” using 4D-CT and “in treatment” using 4D-CBCT.
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Clinical Technology
  • Cone-beam Computed Tomography-derived Adaptive Radiotherapy
    Masato Maruyama, Ryuji Murakami, Yuji Nakaguchi, Kiyotaka Kakei, Eriko ...
    2012 Volume 68 Issue 2 Pages 162-168
    Published: January 20, 2012
    Released on J-STAGE: March 01, 2012
    DOIhttps://doi.org/10.6009/jjrt.2012_JSRT_68.2.162
    JOURNAL FREE ACCESS
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    The purpose of this study was to evaluate the reliability of cone-beam computed tomography (CBCT)-derived adaptive radiotherapy. We evaluate planning computed tomography (pCT) and CBCT in 50 patients who had undergone image guided radiotherapy (IGRT) with CBCT. Irradiated sites included head, neck, chest, abdomen, and pelvis; there were 10 patients in each group. Treatment plans including 153 beam data were recalculated based on CBCT. To compare between pCT and CBCT, we estimated CT values of normal tissues, body contour, effective depth, and monitor units (MU) calculation. The maximum difference in CT values was observed in lung estimation. The 5 mm or more differences in depth were observed in 2 beams of 2 pelvic cases, but CBCT also demonstrated a shift of abdominal wall due to intestinal motility. There were downward trends for the effective depth and MU based on CBCT, especially in lung cases. However, the differences in prescribed dose due to MU calculation were less than 5% because all patients were treated with a multifield irradiation plan. CBCT provides not only precise daily setup but also accurate anatomical information on body contour. In addition, CBCT may be considered as a useful tool for dose calculation.
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Works in Progress
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