Objective To evaluate the relation between lung dosimetric parameters and the risk of symptomatic radiation pneumonitis (RP) in patients with non-small cell lung cancer (NSCLC) who had re-ceived postoperative radiotherapy. Methods From November 2002 to March 2006, 90 patients with NSCLC who had received postoperative 3-dimentinal conformal radiotherapy (3DCRT) were retrospectively analyzed, including 53 with stage ⅢA disease, 25 with stafe ⅢB disease and 12 with stage Ⅰ-Ⅱ disease but positive margins. Seventy (78%) patients underwent lobectomy, 20 ( 22% ) underwent pneumonectomy, and 38 ( 46% ) received adjuvant chemotherapy. The median radiation dose was 60 Gy given in 30 fractions of 2 Gy using 6 MV X-ray. The percentage of the whole lung volume ( Vx ) and the ipsilateral absolute lung volume ( Vipsi-dosewhich received more than a certain dose were calculated. The endpoint was grade 2 and above RP based on CTC AE 3.0. The relation between the dosimetric factors and RP was also analyzed with receiver operating characteristic (ROC) curves. Results Nine patients ( 10% ) developed symptomatic RP ( grade 2 in 7 and grade 3 in 2), and all of them were in the lobectomy group. No RP was observed in patients who received pneumonectomy. Both V30 and V35 were higher in patients with RP than those without ( 19% vs 14% ,U= -2.16,P=0.030, and 15% vs 11%,U= -2.65,P =0.007, respectively). The area under curve in receiver operating characteristic curves based on the relation between incidence of RP and the value of Vipsi-dose was 0. 757. Using Vipsi-30 of 340 cm3 as a cut-off to predict RP, the sensitivity and specificity were 88% and 70%, respectively. The incidence of RP was 3% in patients with Vipsi-30< 340 cm3 compared with 29% in those with Vipsi-30>340cm3 ( X2 = 9.75 , P = 0.003 ) . Conclusions More than340 cm3 of the ipsilateral lung receiving 30 Gy is significantly related to the risk of RP in patients undergoing lobectomy. It is safe for patients who undergo pneumonectomy to receive postoperative 3DCRT if lung V20 is less than 10%.

Objective To study the pattern of lymphatic metastasis in patients with thoracic esopha-geal carcinoma, and to determine the indication and the target volume for post-operative radiotherapy. Meth-ods 229 patients with thoracic esophageal carcinoma who had undergone radical esophagectomy and two-field lymph node dissection were included in this study. The pattern and ratio of lymph node metastasis were analyzed. The effect of the tumor length and pathology stage on lymph node metastasis was studied. Then the indication and target of post-operative radiotherapy for the thoracic esophageal carcinoma was determined. Results Regional lymph node metastasis was found in 57.1% patients with upper thoracic esophageal car-cinoma. For the middle thoracic esophageal carcinoma, the ratio of regional metastasis, skip, upward, down-ward and two-way spread were 39.0%, 19.5% ,5.2% ,28.6% and 7.8% ,respectively. For lower thoracic esophageal carcinoma,downward spread was found in 77.2% patients. For upper thoracie esophageal carci-noma,the proportions of patients with lymph node metastasis were 19.0% ,6.7% ,9.8% and 14.3% in the superior mediastinum, middle mediastinum, inferior mediastinum and abdominal cavity ( x2 = 2.75, P = 0.433). The corresponding figures were 26.1% ,7.4% ,11.8% and 11.9% (x2 = 17.98,P =0.000) for middle thoracic esophageal carcinoma,and 0%, 1.6% ,5.3% and 10.0% (x2= 5.96 ,P = 0. 051 ) for low-er thoracic esophageal carcinoma. The lymph node metastasis ratios were 9.1%, 11.6% and 11.7% in pa-tients with tumor ≤3 cm,3-5 cm and ≥5 cm,respectively (x2 =3.93,P=0. 140), and were much higher in stage Ⅲ disease than those in stage 0 to Ⅱ (19.3% vs4.8% ;x2 =131.06,P=0.000). Conclusions he pattern of lymph node metastasis is complex and extensive in patients with thoracic esophageal carcinoma. For upper and middle thoracic esophageal carcinoma, the extended prophylactic portal is suggested and the superior mediastinum is an important target area. For the lower thoracic esophageal carcinoma,it seems that regional fields could be applied. Post-operative radiotherapy should be performed in stage Ⅲ disease because of the high lymph node metastasis ratio.

Objective To investigate the radiosensitising effect of recombinant human endostatin (endostar) on human lung squamous cancer cell line H-520 in vitro and its mechanism. Methods H-520 cells in exponential growing phase were treated with endostar alone, irradiation alone, or endostar plus irra-diation. Colony-forming assay was used to investigate the cytotoxicity and radiosensitising effects of endostar. Cell survival fractions of all groups were calculated and cell survival curves were fitted by single-hit multi-tar-get model. Cell apoptosis, cell cycle distribution and activated Caspase expression level were investigated by flow cytometry. Results The D0, Dq, D10 and SF2 values of combined treatment group were much lower than those of irradiation alone group. The sensitization enhancement ratio (SER) was 1.50 (ratio of D0 values). Endnstar induced H-520 cell apoptosis in a dose dependant manner. After administration of endostar, H-520 cell proliferation was inhibited, and cell apoptosis rate and apoptotic bodies were increased. After irradiation of 0 Gy, 2 Gy, 4 Gy and 8 Gy, the apoptosis rate of H-520 cells was 4.27% ±0.29%, 14.3% ±1.15%, 28.49% ± 1.58% and 54.79% ± 1.89% in the radiotherapy alone group, and 22.38% ± 1.61%, 35.01% ±1.16%, 46.83%±2.06% and 64.08%±4.28% in the combined treatment group, respective-ly. The difference between the two groups was significant (t = 19.17, 17.79, 25.64 and 3.44,all P < 0.05 ). Flow cytometric analysis showed that cell cycle distribution changed and G0 + G1 phase arrest oc-curred after endostar treatment, while irradiation induced G2 + M arrest. The expression level of activated Caspase in combination group (62.7% ±1.9% ) was higher compared to the control group ( 12.1%± 0. 1% ) , endostar alone group ( 54.6% ±1.0% ) and irradiation alone group ( 34.1%±1.2% ) ( t = 46.69, 6.55 and 22.54 ; all P < 0.05 ). Conclusion Endostar can enhance the radiosensitivity of H-520 ceils by inhibiting cell proliferation, promoting cell apoptosis and facilitating cell cycle redistribution.

Objective To commission a Mobetron intra-operative mobile accelerator and analyze the characteristics of its electron beams. Methods The dosimetrie characteristics of the electron beams genera-ted by Mobetron accelerator were measured and compared with those generated by conventional accelerator (Primus, Siemens). M oberton accelerator can generate electron beams of nominal energies of 4,6,9 and 12 MeV. The measurement items were as followings : percentage depth dose perpendicular to water phantom sur-face and beam profiles parallel to water phantom surface, output factors, applicator leakage, electron beam at-tenuation made by lead blocks,and machine output calibration. The measurement devices included a three-dimensional ( 3 D) water scanning phantom, an electrometer, a 0.6 cm3 Farmer ionization chamber, a parallel-plate ionization chamber and solid water slabs. During measurement, all applicators of different tilt angles and diameters were attached to the machine head,and their ends were adjusted to be tangent to the phantom surface. Results Except for the 12 MeV,skin dose for all energies was no more than 90%. The skin dose was higher for Mobetron accelerator electron beams than for regular electron beams. The Dmax depth in water for a 10 cm flat applicator were 0.7,1.3,2.0 and 2.2 cm for the 4 energies,respectively. The depths of 90% dose were 1.0,1.8,2.7 and 3.6 cm, respectively. The selected flat applicator was just 1 cm larger than the tumor bed. But for the beveled applicators,the field flatness and symmetry became worse,and con-sequently,the applicator size had to be selected based on the isodose distribution. The leakage dose at 1 cm outside the applicator was 1.2% ,5.1%, 10.0% and 9.1%, respectively. The lead thickness for full block was 1.5,3.0,4.5 and 6.0 mm,respectively. Conclusions Through the commissioning of Mobetron accel-erator, the machine characteristics are understood, and the data for clinical implementation and routine quality assurance are acquired.

Objective To study the value of serum S-100B protein in the diagnosis of cerebral radi-ation injuries in patients with brain malignant tumor. Methods Serum S-100B protein level was deteetod by enzyme-linked immunosorbent assay in 56 patients with brain malignant tumor before, during and after radio-therapy. Effects of dose and method of radiotherapy, peritumoral edema degree and Karnofsky performance status on serum S-100B level were studied. Results The levels of serum S-100B protein in the patients be-fore radiotherapy and control group were 0. 039μg/L and 0.044 μg/L ( t = 1.48 ,P =0. 186). The levels of serum S-100B protein before, in the middle of (30-40 Gy) and after (60 -70 Gy) radiotherapy were 0.044 μ/L, 0.049 μ/L and 0.079 μg/L, respectively ( F = 67.26, P = 0.000). The differences after ra-diotherapy were also significant among patients with three methods of radiotherapy (F = 20.32, P = 0.000), different degree of pefitumoral edema ( F = 12.94, P =0. 000 ) and Karnofsky perforrnanee status ( t = 2.71, P =0.007). Conclusions High level of serum S-100B protein is associated with cerebral radiation injuries in patients with brain malignant tumor, which is influenced by the dose and method of radiotherapy, Karnof-sky performance stares and degree of peritumoral edema. High level of serum S-100B protein may serve as an early predictor of cerebral radiation injury.

Objective To evaluate the dose distribution of the target volume and the cranial base in nasopharyngeal carcinoma ( NPC ) treated with facial-cervical fields, and to analyze the differences of dose distribution using different isoeenters with the CT-simulator and treatment planning system (TPS). Methods Eleven patients with nasopharyngeal carcinoma were treated by conventional radiotherapy as their primary treatment. All patients were simulated by the conventional simulator and the field borders were marked with thin lead wires on the mask. Then the patients were scanned by the CT-sim with the same immobilization. The planning CT images were transferred to the TPS and the field borders were copied on the DRR, and then GTV and the cranial base were contoured on the coronal CT slices. Two isoeenters were chosen, including one in front of the 1 st cervical vertebra to measeure the depth of the nasopharynx and the other in front of the 3rd cervical vertebra to measure the depth of the upper neck. The prescription dose of 36 Gy was given in 18 fractions. Dose distributions of GTV and the cranial base were calculated with TPS. Results The actual dose of 95% volume of GTV was 33.31 -35.54 Gy (median 34.83 Gy) and 31.43 -33.36 Gy (median 32.44 Gy) when the isoeenters were set in the nasopharynx and the superior neck, respectively. The corre-sponding actual dose of 95% volume of the cranial base was 17.76 - 34.60 Gy ( median 30.28 Gy ) and 16.52 -32.60 Gy (median 28.52 Gy), respectively. Conclusions For NPC patients treated with conven-tional radiotherapy using facial-cervical fields, the actual dose of GTV and the cranial base is lower than the prescribed dose whenever the isocenter is set in the nasopharynx or the upper neck,which is more significant in the latter. The isocenter should be set in the nasopharynx when the conventional radiotherapy is applied and a boost of 4- 8 Gy should be given when the cranial base is involved.

Objective To estimate and compare the equivalent dose between the intensity modula-ted radiotherapy (IMRT) and conventional radiotherapy (CR) for patients with nasopharyngeal carcinoma (NPC). Methods The peripheral equivalent dose of NPC patients was measured by TLD during IMRT and CR. The whole-body equivalent dose was calculated. Results When prescribed tumor dose of 70 Gy was given, the mean number of accelerator output units were 25235 MU and 8575 MU, and the whole-body e-quivalent dose were 73.65 mSy and 15.28 mSy for IMRT and CR, respectively. Conclusion The equiva-lent dose in IMRT is 4.8 times higher than that in CR for patients with nasopharyngeal carcinoma.

Objective To analyze the outcomes and the role of radiotherapy in breast cancer pa-tients with T1-T2 and one to three positive axillary nodes treated with modified radical mastectomy, and to investigate the prognostic factors for loco - regional recurrence in patients without radiotherapy . Methods Three hundred and seventy breast cancer patients with T1-T2 and one to three positive axillary lymph nodes treated with mastectomy and axillary dissection were retrospectively analyzed. Kaplan-Meier method was used to calculate the overall survival (OS) and loco-regional recurrence-free survival (LRFS) rates. The Logrank test was used for the comparison of the survival curves of patients with or without radiotherapy. Univariate analyses of potential prognostic variables for LRFS were performed. Results The 5-year OS and LRFS rates were 85.4% and 91%. Radiotherapy significantly improved the 5-year LRFS rate ( 100% vs. 89.5% ;x2 = 5.17, P=0.023). However, there was no significant difference in overall survival rate between patients with and without radiotherapy. In univariate analyses, T stage, the number of positive axillary nodes, C-erbB-2 and PR status were the significant predictive factors for LRFS. Conclusions For breast cancer pa-tients with T1-T2. and one to three positive axillary nodes, radiotherapy improves the LRFS, but not OS. T stage, the number of positive axillary nodes, C-erbB-2 and PR status are predictive factors for loco-regional recurrence in patients without radiotherapy.

Objective To compare the characteristics of dose distribution between hypofractionated intensity modulated radiotherapy (IMRT) and hypofractionated stereotactic radiotherapy (SRT) plans in lung tumor and to select an optimal clinical approach. Methods SRT plans were designed for 16 patients with lung tumors who had received IMRT between April 2007 and April 2008. The dose distribution of target volume and normal tissues, conformal index (CI) and heteregenous index (HI) were analyzed using the dose-volume histogram (DVH) for the IMRT and SRT plans. Results The mean dose and equivalent uni-form dose of planning target volume (PTV) in IMRT were similar to those in SRT. SRT had significantly better CI and HI than IMRT (t = 2.77, P < 0.05 and t = - 4.38, P < 0.01 ). The mean lung dose of IMRT and SRT was (492.4 ±368.5) cGy and ( 310.0 ± 73.1 ) cGy, respectively ( t = 1.68, P > 0.05 ). The lung V20 of IMRT and SRT was 6.9% ± 2.1% and 4.2%± 1.9%, respectively ( t = 3.30, P < 0.01 ). No sig-nificant differences were found in the mean dose to the heart or the spinal cord between IMRT and SRT. Conclusions When PTV is less than 57 cm3 or the long diameter of tumor is less than 4.7 cm, hypofrac-tionated SRT has similar dose distribution to hypofractionated IMRT, while the lung dose was lower in the former.

Objective To study the value of image-guided radiotherapy (IGRT) in lung cancer. Methods From Mar. 2007 to Dec. 2007,58 patients with lung cancer were treated with IGRT. Set-up er-rors in each axial direction was calculated based on IGRT images of each patient. The change of GTV was e-valuated on both cone-beam CT and CT simulator images. Results Twenty-two patients with left lung cane-er,30 with right lung cancer,5 with mediastinal lymphanode metastasis and one with vertebra metastasis were included. The set-up error in x,y and z axes was (0.02±0.26) cm, (0.14±0.49) cm and ( -0. 13± 0.27) cm, respectively,while the rotary set-up error in each axis was -0.15°± 1.59°, -0.01°± 1.50° and 0.12°±1.08°, respectively. The set-up errors were siguifieantly decreased by using of IGRT. GTV movement was observed in 15 patients (25.9%) ,including 5 with left upper lung cancer. GTV moving to the anterior direction was observed in 9 patients,including 4 with]eft upper lung cancer. GTV reduced in 23 (44.2%) patients during treatment. Asymmetric GTV reduction of 22 lesions was observed,with a mean re-ductive volume of 4.9 cm3. When GTV began to shrink,the irradiation dose was 4 -46 Gy,with 20 -30 Gy in 9 patients. Conclusions The use of IGRT can significantly reduce set-up errors. GTV movement and reduction are observed in some cases. The time to modify the target volume needs to be further studied.