Radiation therapy is one of the main means of treatment for non-small cell lung cancer (NSCLC). With the rapid development of modern technology, three dimensional conformal radiotherapy, intensity modulated radiotherapy, stereotactic radiotherapy play a very important role in this field. The use of the state-of-art radiation modality can definitely improves the accuracy of the treatment, which results in improving the local control rate of tumor and reducing the adverse reaction of normal tissue. Advances in modern imaging device and its clinical application is the premise of precise radiotherapy. Positron emission tomography and computed tomography (PET-CT) can effectively provide anatomical and functional information; it plays a more and more important role in the diagnosis of NSCLC before radiotherapy, the process of precise target delineation and also the evaluation of therapeutic efficacy after radiotherapy.

Objective To assess the optimal delay time of enhanced scanning with CT-based simulation before cyberknife treatment for pancreatic cancer and to analyze the correlations between the target delineation and the rating items.Methods One hundred and twenty pancreatic cancer patients underwent Philips 16 big core spiral CT before cyberknife treatment.Patients were assigned to three groups randomly with scan delays of 25,45 and 65 s;30,50 and 70 s;and 35,55 and 75 s respectively.After the scanning,the images were evaluated by three associate professors in the field of radiation oncology.To achieve the optimal delay time,the data were compared with a random intercept model of mathematical mean,the Sidak method and One-way ANOVA.Pearson method was used to analyze the correlations between the target delineation and the rating items.Results The tumor boundaries,retroperitoneal lymph nodes,duodenal images,accuracy of target volume delineations in 45 and 65 s,50 and 70 s,55 and 75 s items rating difference had no statistically significant differences (P ＞ 0.05),but significantly superior to those in 25,30,35 s groups respectively(t =3.59-21.68,13.34-15.46,12.42-13.83,P ＜0.05).Therefore,the proposed delay time interval was 50-65 s,and the average value of the target volume delineation was the highest in 55 s group (3.91-± 0.50).When the scan delay time was 55 s,the target delineation was positively correlated with the tumor boundary (r =0.914 4,P ＜ 0.05),and negatively related to the value of other imaging (r =-0.926 3,P ＜ 0.05).Conclusions The recommended delay time interval of pancreatic cancer before cyberknife treatment CT enhanced scanning was 50-65 s,and the optimal time point was 55 s.The target volume delineation was positively correlated with the boundary of the tumor,and significant negatively related to the value of other imaging.

Objective To explore the value of Multiple b value DWI ( MbDWI ) in the short-term efficacy evaluation of cyberknife radiotherapy for locally advanced pancreatic cancer ( LAPC ) .Methods A total of 36 patients underwent both conventional sequence and respiratory triggered MbDWI ( b=0, 25, 50, 75, 100, 150, 200, 400, 600, 800, 1 000 s/mm2 ) before cyberknife radiotherapy, 1month and 3 months after the radiotherapy, respectively.ADCtot, f, Dfast and Dslow were calculated using single and double exponential model and the changes before and after radiotherapy were observed.Results Before radiotherapy, 1 month and 3 months after radiotherapy, the ADCtot values of solid lesions were (1.56 ±0.29) ×10-3 mm2/s, (1.75 ±0.31) ×10 -3 mm2/s and (18.6 ± 0.46) ×10 -3 mm2/s;the values of Dslow were (1.10 ±0.73) × 10 -3 mm2/s, ( 1.19 ±0.97 ) ×10 -3 mm2/s and ( 1.49 ±04.6 ) ×10 -3 mm2 s/; the values of Dfast were (83 .33 ±62 .57) ×10 -3 mm2/s,(124.57 ±123.10) ×10 -3 mm2/s and (108.07 ±96 .67) ×10 -3 mm2 /s; f values were (26.81 ±23.74)%,(23.61 ±22.75)% and (21.34 ±15.36)%, respectively.ADCtot values 1 month and 3 months after treatment were significantly higher than those before treatment and Dslow 3 months post-treatment was higher than that before treatment, and the differences were statistically significant ( both P<0.05) and no other differences between two groups were significant.There were no statistical differences on Dfast and f before and after radiotherapy.Conc lusions ADCtot and Dslow both showed a significant growth trend after cyberknife radiotherapy.The advanced degree of parenchymal cystic in the targeted lesion could reflect the short-term efficacy of cyberknife treatment.

Objective To assess the cumulative doses and side effects after two courses of stereotactic body radiation therapy (SBRT) for pancreatic cancer. Methods Twenty-four pancreatic cancer patients who received two courses of SBRT were enrolled. Organ endangering dose accumulations were calculated by rigid and non-rigid registration. All doses were recalculated to an equivalent dose of 2 Gy per fraction. Results The median of accumulated maximal dosage (Dmax) and dosage per 1cc(D1cc) of the stomach,duodenum and the bowel were 43.87 and 35.28 Gy 3,35.53 and 26.59 Gy3,45.08 and 36.18 Gy3; and the median volume under the dosage of 10Gy (V10) was 107.40,23.98 and 169.26cc, respectively. The median accumulated Dmaxand the dosage of 35% volume(D0.35) of the spinal cord was 8.42 and 7.83Gy3. The median cumulative Dmeanand D2/3of the left and right kidney were 5.18 and 3.65 Gy3, 3.50 and 2.57 Gy3, respectively. The median cumulative Dmeanand D50%of the liver was 5.18 and 3.64Gy3,respectively. The median summed dose to the overlapping radiation field of the two courses was 93.38 Gy3. No grade 3-4 toxicity occurred. Conclusions The cumulative doses to organs at risk as dose constraints were safe and acceptable,which could be used as a reference to evaluate whether a second SBRT could be done after initial SBRT for pancreatic cancer.

Objective To identify the effect of stereotactic body radiation therapy (SBRT) on the survival of patients with recurrent pancreatic cancer after surgery.Methods The data of 104 patients with recurrent pancreatic cancer after surgery who underwent SBRT in the Department of Radiation Oncology of Changhai Hospital,Navy Medical University from February 2012 to December 2016 were retrospectively analyzed.The prescription doses ranged from 35-40 Gy/4-8 f.Survival analysis was performed using the Kaplan-Meier method,and relevant factors affecting patients' survival were screened by the Cox proportional hazards model.Results The median overall survival (OS) and progression free survival (PFS) was 12.5 (11.0-14.0) months and 7.3 (6.0-8.7) months,respectively,while the 1-year rate of OS and PFS was 55.8％ and 22.1％,respectively.Multivariate analysis indicated that tumor stage,biological effect dose (α/β =10,BED10),the decrease of CA19-9 level after treatment,and follow-up chemotherapy were all related factors affecting overall survival;tumor stage,BED10,the degree of pain relief and the decrease of CA19-9 level after treatment were related factors affecting PFS.Conclusions Patients suffering recurrent pancreatic cancer with early tumor stage,normal CA19-9 level and mild pain before treatment could be better treated by SBRT,BED10 ≥60 Gy and follow-up chemotherapy after radiotherapy can prolong the survival of patients.

Objective To investigate the efficacy and safety of stereotactic body radiation therapy (SBRT) for very elderly patients with pancreatic cancer.Methods The clinical data of a total of 149 patients aged from 75 to 90 years with locally advanced or metastatic pancreatic cancer treated by SBRT in Changhai Hospital from January 2012 to December 2016 were retrospectively reviewed.Prescription doses ranged from 3.6-9Gy/fractions,and the total doses were 19.5-49Gy in 3-8 fractions.The level of serum cancer antigen 19-9(CA19-9) before and 3 months after treatment was compared and the radiotherapy biological effective dose (BED10) was calculated.The adverse events of the radiotherapy were observed.Overall survival (OS) and progression-free survival (PFS) were recorded through follow-up,and the factors influencing the patients' survival were investigated by univariate and multivariate analysis.Results All the patients' median OS and PFS were 12.9and 8.3 months,respectively.One-year OS and PFS rate were 55.9％ and 19.5％,respectively.Tumor stage and the decrease of CA19-9 levels ＞50％ at 3 months after treatment and BED10 were independent factors of OS and PFS.No grade 3 or higher toxicities were recorded in all the patients.Conclusions SBRT is safe and effective for very elderly patients with locally advanced or medically inoperable pancreatic cancer.Tumor stage,the decrease of CA19-9 levels after treatment and BED10 were associated with prognosis.

Objective To explore the optimal delay time of enhanced scanning with CT based simulation before cyberknife treatment of carcinoma in different positions of the pancreas.Methods Philips 16 large aperture spiral CT scan was applied.Fifty-three patients with carcinoma in the head of the pancreas and 60 pancreatic cancer patients in the body or tail were randomly assigned to three groups with scan delays of 25,45,and 65 seconds in group A (25s group,pancreatic head n =18,pancreatic body or tail n =21);30,50,and 70 seconds in group B (3 0s,pancreatic head n =17,pancreatic body or tail n =19);and 35,55,and 70 seconds in group C (35s,pancreatic head n =18,pancreatic body or tail n =20),respectively.Images were evaluated by three associate professors of radiation oncology based on image quality score scale.The items rating in different time points were compared using a random intercept model of mathematical mean in three groups.Then the items rating of different time points were compared in pairs using the Sidak method.One-way ANOVA was used to compare the optimal time point of each group,so the optimal delay time of enhanced scanning with CT based simulation before cyberknife treatment of pancreatic cancer was obtained.Results The delayed time points with the highest scores for target delineation of the tumor in the pancreatic head and the pancreatic body or tail by CT enhanced scanning in three groups were 45 s/65 s,50 s/50 s,55 s/75 s,respectively.There was no significant difference in the scan time of 45 s,50 s and 55 s for the tumor in the pancreatic head.Similarly,no significant difference could be found in the scan time of 65 s,50 s and 75 s for the tumor in the pancreatic body and tail.Conclusions The recommended delay time interval for localizing the tumor in pancreatic head by CT enhanced scanning was 45 ～ 55 s,and for the tumor in the pancreatic body or tail was 50 ～75 s.