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Objective@#To study the more safe and accurate guidance scheme of cone beam computed tomography (CBCT) in nasopharyngeal carcinoma.@*Methods@#CBCT was regularly performed on 87 patients with nasopharyngeal carcinoma in Meizhou People's Hospital from November 2014 to August 2015. For each patient, 10 times CBCT scans were obtained pre-treatment. All the setup errors were obtained and analysed on the orientation X (left and right), Y (head and foot) and Z (vertical) axis.@*Results@#With the increase of the number of CBCT scans, there was no statistically significant difference among the mean setup errors of the 10 times scans in X (left and right) and Y (head and foot) directions (all P > 0.05). And there was no statistically significant difference among the mean setup errors of 6 times scans in Z (vertical) direction, but from the beginning of the 7th, the systematic error in Z direction was increasing, the system error of the 7th, 8th, 9th, 10th time was 0.140, 0.292, 0.461, and 0.640 mm. Moreover, the difference of the mean systematic errors among the first 7 times was statistically significant (H = 15.232, P = 0.019), and the differences of the mean systematic errors among the first 8, 9 and 10 times were statistically significant (all P < 0.05).@*Conclusions@#Non-consecutive scans of CBCT could reduce the systematic and random errors. The appropriate frequency of application of CBCT based on the change law of setup errors is an ideal CBCT guidance scheme for nasopharyngeal carcinoma.
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Objective To analyze set-up errors for irradiation of nasopharyngeal carcinoma by using kilo-voltage cone beam computed tomography (kV-KBCT) scanning, and to calculate the external margin from planning target volume (PTV) of nasopharyngeal carcinoma. Methods A total of 150 nasopharyngeal carcinoma patients in Meizhou People's Hospital from December 2014 to November 2016 were treated by image-guided radiation therapy (IGRT), kV-KBCT, CT image scanning matcthed by bone and grey alignment. PTV of nasopharyngeal carcinoma was also calculated. Results According to PTV formula, the external distance before radiotherapy guided by grey alignment was 0.5 mm in X-axis, 0.4 mm in Y-axis, 0.8 mm in Z-axis. While the distance was 0.1 mm in X-axis, 0.5 mm in Y-axis, 1.7 mm in Z-axis guided by bone alignment. After radiotherapy, the external distance guided by grey alignment was 0.4 mm in X-axis, 0.5 mm in Y-axis, 0.9 mm in Z-axis. While the distance was 0.1 mm in X-axis, 0.9 mm in Y-axis, 2.0 mm in Z-axis guided by bone alignment. There was no significant difference in set-up errors of 3 directions and 2 aligned ways before and after treatment.Conclusions The PTV within 3 mm is safe when IGRT is used for directing radiotherapy of nasopharyngeal carcinoma,and kV-KBCT is an effective image equipment.
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Objective To study long-term outcome and prog nostic factors of esophageal squamous cell carcinoma patients treated by three dimensional conformal radiation therapy (3DCRT). Methods 169 patients with unresectable esophageal squamous cell carcinoma treated by 3DCRT were enrolled in the study. The survival rates of 1 year, 3 years and 5 years were estimated by life-table method. Univariate prognostic factor was tested by Log-rank method. Multivariate prognostic factor was analyzed by Cox model. Results The 1 year, 3 years and 5 years survival rates were 63.2%, 34.1%and 21.3%, respectively. Univariate analyses showed that the length of tumor, the site of lesion, chemotherapy, the dose of plan gross tumor volume (PGTV) and the short-term outcomes after treatment were the important prognostic factors for the long-term survival (P< 0.05), and multivariate analyses showed that the length of tumor, chemotherapy and the short-term outcomes after treatment were the independent prognostic factors for the long-term survival (P< 0.05). Conclusions The patients with unresectable esophageal squamous cell carcinoma treated by 3DCRT have a good long-term prognosis. The length of tumor, chemotherapy and the short-term outcomes after treatment are the important prognostic factors for the long-term survival of the patients. Chemotherapy can improve the long-term prognosis significantly.
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Objective To analysis of the efficacy and toxicity of multiple primary cancer of esophagus in three-dimensional conformal radiotherapy and concomitant chemotherapy.Methods Fifteen cases of multiple primary carcinoma of esophagus who refused the operation were collected.The Elekta linac 6 MV/10 MV X ray was used to conformal irradiation in three-four coplanar wild,2 Gy/time,1 time/day,5 times/week.The dose to the target area,CTV 40-50 Gy/4-5 weeks,GTV 60 Gy/6 weeks.TP scheme (paclitaxel+cisplatin) was used in the first day and 29th day,three-dimensional conformal radiation therapy initiated in the second day after chemotherapy.Results 1,3 year local control and overall survival were 86.7 ％ (13/15),33.4 ％ (5/15) and 73.3 ％ (11/15),26.6 ％ (4/15).Class 1-2 and class 3-4 acute radiation esophagitis and leukopenia occurred rates were 86.7 ％ (13/15),13.3 ％ (2/15) and 80 ％ (12/15),20 ％ (3/15).Conclusion Radiation therapy is the better treatment method for multiple primary carcinoma of esophagus when proximal lesions located in upper thoracic and cervical high.Toxic and side-effects can be tolerated of three dimensional conformal radiation therapy combined with chemotherapy in the treatment of multiple esophageal cancer.