ObjectiveTo evaluate the inter-and intra-fractional clinical target volume (CTV) positioning errors of patients receiving postoperative simplified intensity-modulated radiotherapy (SIMRT) using cone beam computed tomography (CBCT).MethodsTwelve patients with liver tumors underwent postoperative SIMRT.CBCT images were acquired before and after the treatment.The clipbox volume for registration included the fiducial markers in the tumor bed and excluded the ribs and vertebral bodies.If any translational parameter of setup error before treatment exceeded 3 mm or rotational parameter exceeded 3°,the treatment couch was adjusted and a verification CBCT was acquired to assess residual setup error.Automatic bone match was used.A total of 214 acquisitions of CBCTs in 111 groups were analyzed.Inter-fractional translational CTV positioning errors in left-right (x),superior-inferior (y) and anterior-posterior (z) axis were calculated in 111 groups,and intra-fractional translational CTV positioning errors in 70 groups.Clinical to planning target volume (PTV) margins were calculated according to the formula:margin =2.0 ∑ + 0.7σ ( ∑ is systematic error,σ is random error).ResultsInter-fractional translational CTV positioning errors in x,y and z axis were -0.03 mm,-0.43 mm,1.02 mm,with systematic error ( ∑ ) of 1.50 mm,5.89 mm,1.97 mm,and random error (σ) of 1.76 mm,4.13 mm,2.42 mm,respectively.Intra-fractional translational CTV positioning errors in the x,y,z axis were 0.04 mm,0.86 mm,- 0.46mm,with systematic error (∑) of 0.46 mm,1.14 mm,0.31 mm,and random error (σ) of 0.95 mm,1.38 mm,0.91 mm,respectively.The calculate CTV to PTV margins were 4.5 mm,15.0 mm,5.8 mm in the x,y,z axis,respectively.ConclusionsThe CTV errors were inevitable when patients with liver tumors received SIMRT.Fiducial markers placed in tumor bed during operation were helpful for accurate positioning error analysis.

Objective To investigate the influence of endorectal balloon on normal tissue dosimetry in prostate cancer patients treated with intensity-modulated radiation therapy (IMRT). Methods Ten patients with prostate cancer were included and each had two sets of planning CT-scans:one with and one without an air-filled endorectal balloon. Target volumes and organs at risk ( rectum, bladder,femoral heads)were contoured on the 20 CT scans and IMRT plannings were performed. The prescription dose was 78 Gy to 95％ of planning target volume. The percentage of volume of organs at risk ( without or with endorectal balloon) receiving more than 10 Gy, 20 Gy, 30 Gy, 40 Gy, 50 Gy, 60 Gy, 70 Gy and 75 Cy (V10 - V70 ,in increments of 10 Gy, and V75 ) were analyzed. Results The V1o - V60 0f rectum with endorectal balloon were 75. 5％ , 52. 6％ , 35. 3％ , 26. 1％, 19. 6％ , 14. 2％ , and those without endorectal balloon were 82. 2％ , 62. 8％ , 43. 9％ , 31. 4％ , 24. 0％ , 17. 1％ , respectively ( X2 = g. 46, P< 0. 01 ). Use of endorectal balloon significantly reduced the dose to the rectum ( v10 - V60 ) . The V70 and V75 of rectum with endorectal balloon were 9. 1％ and 8. 2％; and those without endorectal balloon were 9. 9％ and 6. 2％ respectively ( X2 = 1. 82,P＞0. 05) . The difference was not significant. There were no significant differences in the dose to bladder,left and right femoral head between patients with and without endorectal balloon.Conclusions Endorectal balloon can significantly decrease the medium and low dose volume of rectum for prostate cancer patients treated with IMRT, which may reduce the rectal toxicity.

Objective To analyze the acute and late toxicities in patients with prostate cancer trea-ted with hypofractionated intensity-modulated radiotherapy (IMRT). Methods Between June 2006 and June 2008, 37 patients with prostate cancer were treated with hypofractionated IMRT. The clinical target vol-ume (CTV) was the prostate, seminal vesicles and pelvic lymph nodes in 24 patients, the prostate and semi-hal vesicles in 12, and only the tumor bed in 1. The dose per fraction was 2.3 - 2.8 Gy, with 2.7 Gy in 26 patients. The minimal dose was 62.5-75.0 Gy to the prostate and seminal vesicles, and 50 Gy to the pelvic lymph nodes. Results The median follow-up was 14 months. None of the patients experienced grade 4 a-cute gastro-intestinal (GI) toxicity. Grade 1, 2 and 3 acute GI toxicity occurred in 24.3%, 35.1% and 2.7% of the patients, respectively. The rectal V50>27% and V55>20% were highly significantly associat-ed with grade ≥1 acute GI toxicity. Grade 1,2 and 3 acute genitourinary (GU) toxicity occurred in 68%, 0% and 3% of the patients, respectively. The bladder V50> 10% was significantly associated with grade ≥1 acute GU toxicity. The incidence of late GI toxicity was low. No grade ≥3 late GI toxicity was observed. The incidence of late grade 1 and 2 GI toxicity was 24% and 5%, respectively. The rectal V65> 10% was highly significantly associated with grade ≥1 late GI toxicity. No late grade 4 GU toxicity was observed. The incidence of grade 1, 2 and 3 late GU toxicity was 49%, 11% and 3%, respectively. Grade ≥2 late GU toxicity was correlated with V40, V50 and mean dose of the bladder. Conclusions Acute and late toxicity of hypofractionated IMRT is acceptable in patients with prostate cancer.

Objective To prospectively evaluate the efficacy and toxicity of hypofractionated intensity-modulated radiotherapy (IMRT) for prostate cancer.MethodsFifty-two consecutive patients with localized prostate cancer were enrolled in this study between Feb.2009 and Mar.2011.All patients received hypofractionated IMRT (2.7 Gy/fx,25 fractions,total 67.5 Gy) to the prostate and seminal vesicles.32 high risk patients also received prophylactic irradiation to the pelvic lymph nodes concurrently (2 Gy/fx,25 fractions).Imaging-guided radiotherapy was employed in 35 patients.Androgen deprivation therapy was adopted in 48 of 52 patients.ResultsAfter a median follow-up of 13 months,the mean prostate specific antigen (PSA) was reduced from (40.3 ± 36.6) ng/ml before treatment to (0.5 ± 1.7)ng/ml at the last follow-up.By the time of last follow-up,2 patients (4％) failed.One had PSA failure and the other had both PSA failure and pelvic lymph node relapse.25％ of the patients experienced grade 2 acute gastrointestinal (GI) toxicity and 4％ experienced grade 3 GI toxicity.Acute grade 2 and grade 3genitourinary ( GU ) toxicity occurred in 15％ and 2％,respectively.The incidence of late grade 2 and grade 3 GI toxicity was 17％ and 0％,respectively.Late grade 2 and 3 GU toxicity was 8％ and 2％.The potency was unable to evaluate because most of the patients received androgen deprivation therapy.Conclusions The short-term PSA-free survival after 2.7 Gy/fx,25 fractions' hypofractionated IMRT for localized prostate cancer is favorable,and the acute and late GI and GU toxicity are acceptable.A longer time follow-up is warranted to ascertain the long term efficacy and safety of this regimen.

Objective To compare target dosimetric distribution and normal tissue radiation between different static intensity?modulated radiation therapy ( IMRT) plans and volumetric modulated arc therapy ( VMAT) and to identify the best IMRT plan for patients with primary mediastinal B?cell lymphoma ( PMBCL) . Methods A total of 16 patients ( 8 males and 8 females) with early?stage ( Ann?Arbor stageⅠ) PMBCL were enrolled in this study,with doses of 45 Gy for primary gross tumor volume ( PGTV) and 40 Gy for planning target volume (PTV).Four plans were designed for each patient,consisting of static IMRT (5F?IMRT,7F?IMRT,9F?IMRT) and VMAT,and the target dosimetric distribution,normal tissue radiation dose,and efficiency of each plan were evaluated. The difference of dose was analyzed by analysis of variance. Results The mean conformity index ( CI) and homogeneity index ( HI) for PGTV in 5F?,7F?,9F?IMRT and VMAT were 1. 01 and 1. 10, 1. 01 and 1. 10, 1. 01 and 1. 10, and 1. 01 and 1. 11 ( P= 0. 963 and 0. 843) ,respectively,while these two indices for PTV were 1. 04 and 1. 22,1. 03 and 1. 19,1. 03 and 1. 17, and 1. 08 and 1. 14( P=0. 964 and 0. 969) ,respectively. The parameters of volume and dose were similar on normal tissue ( P= 0. 192?1. 000 ) . The treatment time and number of monitor units in 9F?IMRT were significantly higher than those in other static IMRT plans and VMAT ( P=0. 000,0. 000) ,and among these plans,VMAT had the lowest number of monitor units ( 13 345. 0 MU) and the shortest treatment time ( 5. 9 min) . Conclusions The target volume coverage of 7F?and 9F?IMRT is better than that of 5F?IMRT and VMAT.For early?stage PMBCL,VMAT is not superior to IMRT in terms of dosimetry,especially with a larger area of low?dose radiation to the breast,but it is highly efficient in practice.

Objective:To evaluate the application of visual feedback coaching method, which is embedded in an optical surface monitoring system, in deep inspiration breath holding during the radiotherapy in left breast cancer patients after breast-conserving surgery.Methods:Thirty patients with left breast cancer, who were scheduled to receive the whole breast radiotherapy after breast-conserving surgery, met the requirements of deep inspiration breath holding after respiratory coaching with the visual feedback coaching module in the optical surface monitoring system. Active breathing control equipment was used to control breath-holding state and CT simulation was performed. During treatment, optical surface monitoring system was used to guide radiotherapy. All patients were randomly divided into two groups. In group A ( n=15), visual feedback respiratory training method was utilized and not employed in group B ( n=15). In group A, the visual feedback coaching bar of the optical surface monitoring system was implemented, while audio interactive method was employed to guide patients to hold their breath. Real-time data of optical body surface monitoring were used to compare the interfraction reproducibility and intrafraction stability of breath holding fraction between two groups. Besides, the number of breath holding and treatment time per fraction were also compared. GraphPad prism 6.0 software was used for data processing and mapping, and SPSS 21.0 software was used for analyzing mean value and normality testing. Results:Compared with the control group, the reproducibility in the experiment group was reduced from 1.5 mm to 0.7 mm, the stability was reduced from 1.1 mm to 0.8 mm, the mean number of breath holding required per fraction was decreased from 4.6 to 2.4, the mean beam-on time per fraction from 336 s to 235 s, and the treatment time per fraction was shortened from 847 s to 602 s (all P<0.05), respectively. Conclusions:The application of visual feedback coaching method can improve the reproducibility and stability of breath holding during radiotherapy for left breast cancer, and it can also effectively reduce the number of breath holding and shorten the treatment time per fraction.

Objective Radiotherapy is the primary therapy for early stage nasal-type NK/T-cell lymphoma of the nasal or Waldeyer ring. This study aimed to investigate the clinical outcome of the disease treated with intensity-modulated radiation therapy (IMRT). Methods From November 2003 to June 2008, 48 patients with nasal or Waldeyer ring NK/T-ceil lymphoma underwent IMRT. The tumors were located in the nasal in 42 patients ,and the Waldeyer ring in 6. According to the Ann Arbor staging system, the disease was stage Ⅰ_E in 37 patients (77%), stage Ⅱ_E in 11 (23%). Of these patients, 22 received radiotherapy alone, the other 26 received combined chemotherapy and radiotherapy. Prescribed radiation dose was defined as a minimun dose of 95% PTV. Acute and late toxicities were scored by Radiation Therapy Oncology Group morbidity criteria. Survival probabilities were estimated using Kaplan-Meier method. Results With a median follow-up of 18 months, the 2-year local control, overall survival and progression-free survival rates were 100%, 75% and 73%, respectively. The average maximum, mean and minimum delivered doses were 62.6 Gy, 55.0 Gy and 20.3 Gy to the PTV. Only 2.4% of the PTV received less than 95% of the prescribed dose. The average maximum dose to the brain, spinal cord, optic chiasm, left optical nerve, right optical nerve, left len and right len was 43.5 Gy, 32. 7 Gy, 48.2 Gy, 50. 3 Gy, 51.3 Gy, 7. 8 Gy and 7.6 Gy, respectively. The average mean dose to the left parotid, right parotid, pituitary, left T-M joint and right T- M joint was 17. 1 Gy , 16. 5 Gy , 32. 5 Gy , 47.3 Gy and 46. 8 Gy , respectively. Acute mucositis was observed in 37% of patients with Grade 1, 41% with Grade 2, and 16% with Grade 3. Skin toxicity was observed in 78% of patients with Grade 1 and 16% with Grade 2. Acute xerestoma was observed in 65% of patients with Grade 1 and 18% with Grade 2. Conclusions IMRT provids excellent tumor target coverage and reduces the dose to the critical normal tissues such as the salivary glands. Longer follow-up is needed to assess the long-term overall survival and local control.

BACKGROUND:Currently,different methods of model establishment have been derived from different injury modes of spinal cord injury.Traditional physical injury modeling methods have their own advantages and disadvantages,and there is a lack of more effective and stable animal models of spinal cord injury. OBJECTIVE:To establish a reproducible,controllable,trauma-free,low-mortality,more stable,widely applicable,and short-term postoperative care rat model of spinal cord injury. METHODS:Forty Sprague-Dawley rats with similar body mass and ages were randomly divided into a control group and an improved group,with 20 rats in each group.Animal models of spinal cord injury in the control group were constructed using a clip model method,while the improved group used a modified ligation method based on the compression method to make the spinal cord injury models using suture ligation based on fenestration.Postoperative comparisons were made between the two groups,assessing urination behavior,hematuria,pyuria(infection rate),mortality,scoliosis rate and Basso-Beattie-Bresnahan locomotor rating scale scores at 1,3,5,and 7 days after modeling. RESULTS AND CONCLUSION:Compared with the conventional modeling method,the modified ligation method based on the compression method resulted in faster recovery of urination behavior,lower hematuria rate,lower infection rate,lower mortality rate,lower scoliosis rate,and more concentrated and stable Basso-Beattie-Bresnahan scores(all below 2 points within 1 week).This proves that the modified ligation method based on compression is more suitable for the establishment of spinal cord injury models in rats.

Objective: To investigate the dosimetric characteristics of conventional two-dimensional radiotherapy of the chest wall, supra-and infra-clavicular regions, and the incidental irradiation dosage of the internal mammary region after modified mastectomy in breast cancer patients. Methods: Clinical data of 20 breast cancer patients including 10 left and 10 right cases who received radiotherapy after modified mastectomy between 2015 and 2016 were retrospectively analyzed. All patients received irradiation to the chest wall, supra-and infraclavicular regions at a prescription dose of 43.5 Gy in 15 fractions with conventional technique. One anterior-posterior (AP) photon field irradiation was delivered for the supra-and infra-clavicular regions, and one electron field for the chest wall. The supra-and infraclavicular regions were re-planned by using two AP/PA fields and the doses of organ at risk were evaluated. Results: With conventional radiotherapy, the D₉₀ of the supra-and infra-clavicular regions were more than 39.15 Gy (EQD₂≥45 Gy) in 17 patients (85%), and the median D₉₀ of the chest wall was 35.38 Gy. The median dose of incidental internal mammary region was 13.65 Gy. Patients with lower body mass index (BMI) received higher D₉₀ in both supra-and infra-clavicular and chest wall irradiation (P=0.039, 0.347). Conclusions Irradiation at D₉₀ of 39.15 Gy to the supra-and infra-clavicular regions with AP/PA fields can meet the prescription dose requirement of ≥90% in most cases and does not increase the irradiation dose to normal tissues. The dose distribution of one electron field of the chest wall is poor. Incidental internal mammary region can be irradiated at a limited dosage. BMI is an influencing factor for dose distribution.

Objective:To establish the basic procedures of the application of optical surface monitoring system (OSMS) in the deep inspiration breath hold (DIBH) radiotherapy for patients with left sided breast cancer and compare the performance of OSMS and cone-beam CT (CBCT) in the determination of the set-up errors of DIBH radiotherapy for patients with left sided breast cancer.Methods:Twenty patients with left sided breast cancer received DIBH radiotherapy. Through the registration of CBCT images with the planning CT images, and the registration of OSMS radiography images with the outer contour of the body surface, translational set-up errors and rotational errors were determined along the lateral-medial ( Rx), superior-inferior ( Ry) and anterior-posterior ( Rz) directions. Pearson correlation analysis was performed to evaluate the correlation of the set-up errors determined by two methods, and Bland- Altman plot analysis was used to assess the coincidence of these two methods. Results:Two methods were positively correlated. The Rz volume was 0.84, 0.74 and 0.84 in the x, y and z directions, and 0.65, 0.41 and 0.54 in the Rx, Ry and Rz directions, respectively (all P<0.01). The 95% CI of agreement were within preset 5 mm tolerance (-0.37-0.42cm, -0.39-0.41cm, -0.29-0.49cm ) in x, y and z directions for two methods. The 95% CI of agreement were within preset 3 ° tolerance -2.9°-1.4°, -2.6°-1.4°, -2.4°-2.5°in Rx, Ry and Rz directions for two methods. The system errors of 20 patients with left sided breast cancer receiving DIBH radiotherapy were <0.18cm and the random errors were <0.24cm. Conclusions:OSMS is equivalent to CBCT in the determination and stimulation of set-up errors for patients with left sided breast cancer receiving DIBH radiotherapy. The combination of CBCT and OSMS is a safe and reliable method.