The clinical application of in-house double lower limb auxiliary device in treating pelvic tumors.

OBJECTIVE: Patient positioning accuracy is critical in radiotherapy. To improve the patient positioning accuracy, a double lower limb auxiliary device has been developed to fix pelvis patients to treatment couch. A clinical study for comparing new device to conventional devices has been performed. MATERIALS AND METHODS: Thirty patients with pelvic tumor were randomly divided into conventional thermoplastic membrane fixation group (conventional fixing group) and conventional thermoplastic membrane plus lower limb auxiliary fixture group (auxiliary fixing group). The setup error was acquired by simulator position alignment with center field digital radiograph reconstruction (DRR) image from treatment planning system, The correlations between the conventional fixing group and the auxiliary fixing group were analyzed using Pearson's Chi-squared test. RESULTS: Set-up errors in conventional fixing group and auxiliary fixing group were respectively 3.8 ± 1.5 mm and 1.4 ± 0.9 mm (P< 0.02), 5.4 ± 2.5 mm and 1.2 ± 1.2mm (P < 0.001), 2.2 ± 1.3 mm and 1.9 ± 1.0 mm (P < 0.05) in the bilateral, superior-inferior and anterior-posterior direction. CONCLUSION: The double lower limbs auxiliary device can reduce pelvic patient positioning errors. It is very helpful in improving the daily clinical setup accuracy.

Influence of pathological characteristics on radiotherapeutic target area of esophageal squamous cell carcinoma / 中华放射肿瘤学杂志

Objective To investigation the pathological characteristics of esophageal squamous cell carcinoma to provide reference criteria for delineating the target area in radiotherapy.Methods Fifty-two patients from the Fourth Hospital of HeBei Medical University underwent resection whom all had been proved to have esophageal squamous cell carcinoma before operation.Chest CT was scanned and transmitted to the 3- dimensional conformal planning system for radiotherapy by VRX-16 scanner.The lesion of esophageal carcinoma was delineated in the 3-dimensional rebuild CT image and the lesion volume was computed by digital rebuild program.Every surgically resected specimen was made into pathologic giant section.The actual size of the specimen was obtained by calculating the size under the microscope with the shrinkage ratio.Multicentric carcinomatous lesion,severe dysplasia and direct intramural infiltration were observed in the giant section with a microscope and the order of such pathological characteristics were analysed statistically.Results 1.The tumor length by different method of preparation of operated specimens differed obviously.The longest was shown by CT. 2.Multicentric carcinomatous lesion was found in 15(29%)cases out of 52 patients.Proximal to the tumor,the mean distance between the multicentric carcinomatous lesion and the main lesion plus the length of the multicentric carcinomatous lesion was 3.02?1.45cm.Distal to the tumor,it was 2.60?2.44 cm.Severe dysplasia was found in 28 patients.Proximally,the mean distance between the severe dysplasia and the main lesion plus the length of the severe dysplasia was 2.45?1.30 cm.Distal to the tumor,it was 3.24?2.19 cm.Direct intramural infiltration was found in 41 patients,of which the mean length being 2.80?1.52 cm proximally and 2.02?1.51 cm distally. 3.Tumor thrombus was found in 6 patients and lymphoduct infiltration in 36 patients.Direct intramural infiltration was found at higher incidence in specimens complicated with lymphoduct infiltration(86%)and those complicated with tumor thrombus(91%).There were no apparent factors affecting severe dysplasia.The proximal distance to direct intra- mural infiltration was much longer than distally.Conclusions Multicentric carcinomatous lesion,severe dysplasia and direct intramural infiltration may be observed in esophageal squamous cell carcinoma.Multicentric carcinomatous lesion and direct intramural infiltration are obviously correlated with lymphoduct infiltration.To cover 95% of the microscopic extension,a margin of 5.0 cm is needed proximal to the base of gross tumor volume,and 7.5 cm distal to it.To cover 90% of the microscopic extension,a margin of 4.5 cm is needed proximally,and 5.0 cm distally.