Measurement of the imaging dose for head and neck cancer by different image-guided methods / 中国医疗器械杂志

ABSTRACT

<p><b>OBJECTIVE</b>To measure the imaging dose in the head phantom by different image-guided methods.</p><p><b>METHODS</b>The imaging dose was measured in a cylindrical phantom on a Varian Clinac iX linear accelerator equipped with EPID, OBI, CBCT using a PTW 0.6 cc ion chamber with UNIDOS E dosimeter. 2D images were acquired by two perpendicular fields (0 degrees & 270 degrees), and the 3D images by CBCT.</p><p><b>RESULTS</b>The 2D imaging average dose for OBI (KV X-ray) was 0.74 mGy in the head phantom. It was significantly lower than 90.93 mGy for EPID (MV X-ray) and the image quality was better. For a standard CBCT (KV X-ray), the imaging average dose was 4.77 mGy. For a low dose mode, the imaging dose was 50% of the standard mode. Moreover, 3D images could match accurately.</p><p><b>CONCLUSION</b>For the OBI system, the imaging dose is lower and image quality is better than EPID. The 3D image-guided method for CBCT is better than 2D and is also safe for daily position verification. Therefore, during treatment positioning, the appropriate image-guide methods and scanning parameters can effectively reduce the additional dose to the patients.</p>