Is linac-based volumetric modulated arc therapy better than helical tomotherapy in the radiotherapy of nasopharyngeal carcinoma?

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• 作者：Vincent W. C. Wu ; Bing-kin Choi ; Ho-nam Chan ; Ruby Lam…
• 关键词：Nasopharyngeal carcinoma ; Radiotherapy ; Volumetric modulated arc therapy ; Helical tomotherapy ; Dosimetric comparison
• 刊名：Journal of Radiation Oncology
• 出版年：2015
• 出版时间：March 2015
• 年：2015
• 卷：4
• 期：1
• 页码：29-35
• 全文大小：1,931 KB
• 参考文献：1. Chen, AM, Marsano, J, Perks, J (2011) Comparison of IMRT techniques in the radiotherapeutic management of head and neck cancer: is tomotherapy better than step-and-shoot IMRT?. Technol Cancer Res Treat 10: pp. 171-177
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• 刊物主题：Oncology; Imaging / Radiology; Cancer Research; Surgical Oncology; Surgery; Radiotherapy;
• 出版者：Springer Berlin Heidelberg
• ISSN：1948-7908

文摘

Objective Volumetric arc therapy (VMAT) and helical tomotherapy (HT) are currently the two state-of-the-art rotational intensity-modulated radiotherapy (IMRT). When compared with conventional IMRT, linac-based VMAT can shorten the treatment time while HT has been claimed to produce a better dosimetric outcome. The aim of our study was to evaluate whether the more “efficient-VMAT can produce a comparable or better dosimetric outcome when compared with HT for the treatment of nasopharyngeal carcinoma (NPC) patients. Methods Sixteen primary NPC patients treated by HT were recruited. In addition to the original HT plans, two-arc VMAT plans using the same patient data and dose requirements were generated for each patient. The dosimetric evaluation of the plans included the comparison of conformity index (CI), homogeneity index (HI), dose to 2 and 98?% volume (D 2 and D 98) of the planning target volume (PTV) of the NP, and left and right lymphatic regions. For the organs at risk (OARs), maximum dose or D 2 and mean dose were used for serial and parallel organs, respectively. Student’s paired t test or Wilcoxon signed-rank test was used to check for significant difference. Results The dose to the NP target was similar between the two techniques. For the nodal targets, the VMAT plans produced higher mean D 2 and lower HI values. For the OARs, the spinal cord and spinal cord doses were higher in the VMAT plans than in the HT plans, whereas the opposite happened in the optic chiasm and pituitary gland. The doses to the brain stem, lens, and optic nerve did not show a significant difference. Conclusion Both systems delivered satisfactory dose distributions and kept the dose to OARs below their tolerance. However, if the parotid gland toxicity is a concern in the treatment, HT would be more favorable because it is relatively more effective in sparing the parotid gland. Otherwise, the linac-based double-arc VMAT would be recommended because of its shorter treatment time.