High dose three-dimensional conformal boost using the real-time tumor tracking radiotherapy system in cervical cancer patients unable to receive intracavitary brachytherapy.

PURPOSE: The purpose of this study is to evaluate the clinical results of treatment with a high dose of 3-dimensional conformal boost (3DCB) using a real-time tracking radiation therapy (RTRT) system in cervical cancer patients. MATERIALS AND METHODS: Between January 2001 and December 2004, 10 patients with cervical cancer were treated with a high dose 3DCB using RTRT system. Nine patients received whole pelvis radiation therapy (RT) with a median dose of 50 Gy (range, 40-50 Gy) before the 3DCB. The median dose of the 3DCB was 30 Gy (range, 25-30 Gy). Eight patients received the 3DCB twice a week with a daily fraction of 5 Gy. The determined endpoints were tumor response, overall survival, local failure free survival, and distant metastasis free survival. The duration of survival was calculated from the time of the start of radiotherapy. RESULTS: All patients were alive at the time of analysis and the median follow-up was 17.6 months (range, 4.9-27.3 months). Complete response was achieved in nine patients and one patient had a partial response. The 1- and 2-year local failure free survival was 78.8% and 54%, respectively. The 1- and 2-year distant metastasis free survival was 90% and 72%, respectively. Late toxicity of a grade 2 rectal hemorrhage was seen in one patient. A subcutaneous abscess was encountered in one patient. CONCLUSION: The use of the high dose 3DCB in the treatment of cervical cancer is safe and feasible where intracavitary brachytherapy (ICBT) is unable to be performed. The escalation of the 3DCB dose is currently under evaluation.

High dose three-dimensional conformal boost (3DCB) using an orthogonal diagnostic X-ray set-up for patients with gynecological malignancy: a new application of real-time tumor-tracking system.

The feasibility and accuracy of high dose three-dimensional conformal boost (3DCB) using three internal fiducial markers and a two-orthogonal X-ray set-up of the real-time tumor-tracking system on patients with gynecological malignacy were investigated in 10 patients. The standard deviation of the distribution of systematic deviations (Sigma) was reduced from 3.8, 4.6, and 4.9 mm in the manual set-up to 2.3, 2.3 and 2.7 mm in the set-up using the internal markers. The average standard deviation of the distribution of random deviations (sigma) was reduced from 3.7, 5.0, and 4.5 mm in the manual set-up to 3.3, 3.0, and 4.2 mm in the marker set-up. The appropriate PTV margin was estimated to be 10.2, 12.8, and 12.9 mm in the manual set-up and 6.9, 6.7, and 8.3 mm in the gold marker set-up, respectively, using the formula 2Sigma + 0.7sigma. Set-up of the patients with three markers and two fluoroscopy is useful to reduce PTV margin and perform 3DCB.