Dosimetric study of three dimension therapy plans in patients with squamous cell carcinoma of tongue receiving postoperative intensity-modulated radiotherapy or conventional radiotherapy / 上海第二医科大学学报

ABSTRACT

Objective To evaluate the dose distribution in clinical target volume (CTV) and organs-at-risk (OARs) in three dimension therapy plans in patients with squamous cell carcinoma of tongue receiving postoperative intensity-modulated radiotherapy (IMRT) or conventional radiotherapy (CRT) by dosimetric study. Methods Thirty-five patients with squamous cell carcinoma of tongue were divided into CRT group(n=17) and IMRT group(n=18). All patients underwent head-and-neck immobilization with a thermoplastic mask and planning CT scan, and target volume and OARs were contoured. Dose calculation and plan optimization were performed. All three dimension plans passed quality assurance before treatment. The dosimetry of therapy plans with IMRT or CRT in target volume and OARs dose distribution was compared by dose-volume histogram (DVH), conformity index (CI) and homogeneous index (HI). Results There were significant differences in D95 (isodose line to cover 95 percent target volume), CI, HI, minimum dose and maximum dose in CTV of therapy plans between patients with IMRT and CRT(P < 0.01), and there was no significant difference in mean dose of CTV(P > 0.05). The radiation dose on salivary glands (both parotid glands and contralateral submandibular gland) in patients with IMRT was significantly lower than that in patients with CRT(P < 0.01). Conclusion Compared with dose distribution of CRT plans, there are more advantages in improving dose distribution at the target volume and sparing salivary glands in IMRT therapy plans in patients with squamous cell carcinoma of tongue.