Objective To study the maintenance of BJ-6B accelerator. Methods Analyzed retrospectively the maintenance record of BJ-6B accelerator, including phenomena, causes and handle from 2002 to 2009. Results In 231 records, there were motion-controlling 64, hand-controlling-pendant 20.modulator 41, anti-peak overload 36, charging overload 5. Flatness 7, mechanical 21, digital-display 20,others lie in magnetron power, water-cooling system, light-indicator system, dose-monitor system and wedge system. Motion-controlling system is the highest among those, followed by high-voltage modulator and mechanical system. Conclusions The down time for BJ-6B accelerator is low because of its perfect technology. To keep its stability in clinic, the hospital authorities should emphasize training of engineer for improving their maintenance ability. The engineer must be familiar with the circuit diagram, check the electric wire and machine unit on time and prepare unit for maintenance. The temperature and humidity in machine house must be controlled on demand. The engineer must pay attention to machine parameters when beam is on for avoiding the spark's damage to magnetron and accelerating-tube

Objective To explore a new method of comparing the references images first to enhance the precision of the central point of the radiation treatment planning(RTP), try to establish a reference standard for this method in the nasopharyngeal cancer(NPC)and carcinoma of utercin cervix in the work of position verification. Methods For 50 RTPs of NPC and 20 RTPs of carcinoma of utercin cervix, the reference-CT-images in set-up and in position verification were compared, and to measure the difference between the two images. Then, in the same way, compare and measure the difference in the central-pointimages. Results For NPC, there was over 90% RTPs in which every difference measured was less than 2 mm;for carcinoma of utercin cervix, over 80% RTPs meet the criterion:the value of △MU1 ' or △MU2' was less than 5 mm and the others are less than 3 mm. Conclusions By comparing the references-CT-images in set-up and in position verification, the precision of the central point of the RTP is enhanced. The marks on the skin become more credible. So, it is feasible to perform the criterions in the work of position verification:for NPC every difference measured is less than 2 mm;for carcinoma of utercin cervix the value of △MU1 ' or △MU2 ' is less than 5 mm and the others are less than 3 mm.

Objective To investigate the correlation between dose volume histogram(DVH)of tumor targets and organs at risk(OAR)at CT-image based 192Ir brachytherapy and effects and complications for patients with locally advanced cervical cancer. Methods Ten patients with FIGO stage ⅢB cervical cancer received CT image-based 192Ir intracavitary brachytherapy after 54 Gy of three-dimentional four-field pelvic external beam radiotherapy and concurrent weekly cisplatin chemotherapy. Before each brachytherapy,CT images were acquired with applicators in place. Gross tumor volume(GTV), clinical target volume (CTV)and OAR were contoured and inverse treatment planning was designed and optimized by using PLATO treatment planning system. Conventional two-dimensional plans were also designed for comparison.The total intracavitary brachytherapy dose was 30 -42 Gy in 5 -7 fractions. The patients were followed, and the local control and complications were analyzed. The biologically equivalent dose(BED)and biologically equivalent dose in 2 Gy fractions(BED2)for GTV, CTV and OAR were calculated. The minimum dose in the most irradiated tissue volume 2 cm3(D2 cm3)adjacent to the applicator of the sigmoid colon, rectum,bladder and small bowel was determined from the DVH. Results The 1-year local pelvic control rate was 90% and grade 1-2 late complication of sigmoid colon and rectum was 50%. No grade 3 or more complications developed. On CT-image based planning, the BED and BED2 to 90% of the CTV(D90)were 95.50 Gy ± 7. 81 Gy and 79. 73 Gy ± 6. 57 Gy. The BED and BED2 to 90% of the GTV(D90)were 101.86 Gy ± 7.27 Gy and 84. 95 Gy ± 6. 1 Gy. The volume enclosed by 90% of prescribed dose(V90)for GTV and CTV were 92% ±4% and 87% ±7% respectively. The D2cm3 for rectum and sigmoid colon were 74. 97 Gy ±1.64 Gy and 67. 93 Gy ± 4. 30 Gy(EQD2, α/β = 3). Comparing with 2D brachytherapy plans , CT - image based planning has improved D90 and V90 for GTV and CTV with similar dose at point A and rectum reference point. Conclusions Computer tomography-image based 192Ir brachytherapy has resulted in the better dose distribution to the tumor targets with excellent tumor control and acceptable toxicity.

Objective To observe the therapeutic effect and toxicity of chemoradiation of locally advanced non-small cell lung cancer by intensity modulated irradiation combined with pemetrexed and cisplatin. Methods Fourty-two patients presented with Ⅲ - stage non-small cell lung cancer(Ⅲ、 25 patients, ⅢB 17 patients)received concurrent chemoradiotherapy. Intensity modulated irradiation technique was used to the total dose of 66 Gy and concurrent chemotherapy consisted of pemetrexed 500 mg/m2 on Day 1 and cisplatin 75 mg/m2 on Day 1 by intravenous infusion once every 3 weeks at the initiation of radiation.Patients received 4 cycles of chemotherapy. Results Thirty-four patients finished the whole of therapeutic schedule. And 2 patients received radiation with total dose of 54 Gy, 2 patients 56 Gy;3 patients received 2 cycles of chemotherapy, 1 patients 3 cycles of chemotherapy. Total effective rate was 79%. There were 2 patients with ≥3 grade marrow depression, 3 patients with 3 grade radiation esophagitis, 4 patients with ≥2 radiation pneumonitis, and 1 patient with 3 grade mucositis. The 1-year survival rate was 65%.Conclusion Recent effect was favourable and toxicity was tolerable for chemoradiation of locally advanced non-small cell lung cancer by intensity modulated irradiation combined with pemetrexed and cisplatin.

Objective To compare dose distribution in gamma knife radiotherapy plan, conformal radiotherapy(CRT)plan and intensity modulated radiotherapy(MRT)plan for patients with small mass in lung, and evaluate their characters. Methods Fourteen patients with small mass in lung participated in the study. Gamma knife radiotherapy plan(plan 1), CRT plan(plan 2)and IMRT plan(plan 3)were made for each mass. The planning target volume(PTV)and the dose include 95% PTV were consistent.Conformal index(CI), homogeneity index(HI), lung V5 ,V10 ,V20 ,V30 and the max dose of esophagus and spinal cord were analyzed. Paired samples t-test was used for comparison between each two plans. Results The CI of the plan 1,2 and 3 were 0. 58,0. 46 and 0. 63, respectively. CI of the plan 1 ＞ that of the plan 2 (t= -3.95,P =0.000),plan 3 ＞ plan 2(t = -6.01 ,P =0.000),plan 1 =plan 3(t =1.64,P =0.116);HI of the plan 1,2 and 3 were 1.66,1.10 and 1.07 respectively. HI of the plan 1 ＞ plan 2 ,plan 1 ＞ plan 3(t= -20.52,21.41 respectively, both P=0. 000),plan 2 = plan 3(t= -1.08,P=0.294). The wholelung V5 ,V10 ,V20 and V30 were 10.0% ,5.6% ,2. 4% and 1.2%, respectively, in plan 1 ;20. 2% ,13. 4%,6. 9% ,3.0%, respectively, in plan 3; and 26. 5%, 18. 0%, 11.4% and 4. 6%, respectively, in plan 2.The V5, V10, V20 and V 30 of the plan 1 ＜ in plan 2(t = 9. 68,8. 41,5. 45,5. 14, all P = 0. 000), the V5,V10,V20 and V30 of the plan 1 ＜ in plan 3(t=7.58,8.95,6. 15,4.78, respectively, all P=0.000),the V5 ,V10, V20andV30 oftheplan2 ＞ inplan3(t =9. 71,5. 91,4. 13,3.91, respectively, allP =0.000).The max dose of esophagus in plan 1 ,2 and 3 were 24.93 ± 21.54, 31.90 ± 18. 75, 29. 19 ± 23.09 Gy,respectively, plan 1 ＜ plan 2(t = -2. 71 ,P=0.013),plan 1 = plan 3(t = - 1.49,P =0. 152),plan 2 =plan 3(t = 1.35, P = 0. 193). The max dose of spinal cord in plan 1,2 and 3 were 12.07 ± 10. 67,17.70 ±11.35 and 8.92 :± 10. 04 Gy, respectively, plan 2 ＞ plan 1 ＞plan 3(t = -2. 38,2. 29,4. 83,P=0. 1027,0.033,0.000);All three plans of each mass meet the needs that the max dose of the esophagus≤60 Gy and the max dose of spinal cord ≤40 Gy. Conclusions The dose of the normal lung was lower, but the HI and the max dose of spinal cord were higher in Gamma knife radiotherapy plan than those in the CRT and the IMRT plan of the small mass in lung.

Objective To compare the results of three dose verification solutions of esophageal carcinoma IMRT plans. Methods Seven esophageal carcinoma cases were planned with Pinnacle 8.0 h.The MATRIXX and Delta4 were chosen as the two-dimensional dosimetry and three-dimensional dosimetry.IMRT plans and Delta4 phantom plans were also recalculated by Monte Carlo. Gamma values were evaluated for MATRIXX and Delta4 with 3 mm/3% gamma criteria. For the comparison of Pinnacle, Delta4 and Monte gamma maps, the dose distribution in central plane, dose profiles and dose-volume histograms were used to evaluate the agreement. Results The gamma maps comparison show that with 3 mm/3% gamma criteria an over 98% pass ratio was obtained by MATRIXX measurement. A 94. 4% gamma pass ratio whicl.contains 4 fields gamma pass ratio lower than 90%, was obtained by Delta4 measurement. A 97.6% and 99. 8% gamma pass ratio was obtained between the Delta4 measurement and Monte Carlo simulation with 2 mm/2% and 3 mm/3% gamma criteria. The dose distribution in central plane and dose profiles from Pinnacle calculation were almost in agreement with both the Monte Carlo simulation and Delta4 measurement. The DVH plot have slightly differences between Pinnacle and Delta4 measurement as well as Pinnacle and Monte Carlo simulation, but have excellent agreement between Delta4 measurement and Monte Carlo simulation. Conclusions It was shown that all the three methods can be used very efficiently to verify esophageal carcinoma IMRT delivery, Delta4 and Monte Carlo simulation no data missed. The primary advantage of Delta4 is the fact it can measure true 3D dosimetry while Monte Carlo can simulate in patients CT images but not in phantom.

Objective In this retrospective study, we analyzed the magnetic resonance imaging (MRI)and computed tomography(CT)scans of patients with prostate cancer to investigate the relationship between the apex of prostate and the anatomic structures visible in CT, and to provide evidence for localizing the prostatic apex in radiation treatment planning. Methods MRI and CT scans from 108 patients with prostate cancer were analyzed to measure the distance between the prostatic apex and the bottom of ischial tuberosities,the bottom of obturator foramen, the bottom of pubic symphysis and the bulb of the penis. The volume of prostate was calculated and the relationship between the size of the prostate and the localization of the prostatic apex was analyzed. Results The prostatic apex is located 13. 1 mm ±3. 3 mm superior to the bulb of the penis, 11.0 mm ± 5.4 mm superior to the bottom of obturator foramen, 31.3 mm ± 5.5 mm superior to the bottom of ischial tuberosities, and 7. 1 mm ± 4. 7 mm superior to the bottom of obturator foramen. There was no correlation between the size of prostate and the localization of the prostatic apex(R =0. 07、-0. 33, all P ＞ 0. 05). Conclusions Ninety-five percent of patients had a prostatic apex that is above the bulb of the penis 6 mm, and 100% of patients had a prostatic apex that is above the bottom of obturator foramen.

Objective To evaluate the clinical value of regular and dual-time-point 18-fluorodeoxyglucose positron emission tomography-CT(FDG PET/CT)imaging for recurrence and metastasis in esophageal carcinoma(EC)after curative esophagectomy. Methods A retrospective study was done on 48 patients received curative esophagectomy, who underwent FDG PET/CT scans to detect doubtful recurrent or metastatic lesions. The diagnostic accuracy of FDG PET-CT was assessed with the help of pathological findings as well as clinical or follow-up data. Using Fisher's Exact Test from SPSS 11.5 to analyze the data.Results Of the 48 patients, after a median follow-up of 21.5 months, 61 sites of local and regional recurrence or metastasis were finally confirmed in 34 patients. The sensitivity, specificity and accuracy of regular FDG PET/CT imaging in detecting recurrence of all sites were 93.44%, 74.29% and 86.46%respectively. The specificity and accuracy of local recurrence and regional metastasis were 57.14% ,78.95% and 77.78% ,84.62%, respectively. The sensitivity, specificity and accuracy of dual-time-point FDG PET/ CT imaging in detecting local and regional recurrence(96.97% ,96.00% and 96.55%)were higher than those of regular FDG PET/CT(90.90%, 72.00% and 82.76%)and there were significant differences of specificity and accuracy(P = 0.049, P = 0.029). Conclusions Regular FDG PET/CT imaging is highly effective in detecting recurrence and metastasis in EC patients after curative esophagectomy despite the low specificity and accuracy. Dual-time-point FDG PET/CT imaging can elevate the specificity and accuracy.

Objective To analyze the result of3-dimensional conformal radiotherapy(3DCRT)and operation of early stage esophageal carcinoma. Methods Ninety-three patients with early stage esophageal carcinoma were treated with 3DCRT from October 2000 to December 2006. The total dose was 50 -70 Gy/25 -35F/5 -7 w. Toxicities and survival rates were evaluated by Kaplan Meier method and the factors of death were analyzed. Results In the 3DCRT group, 79, 42 and 13 cases were followed up for at least 1-,3-,and 5-year, respectively. Follow-up rate was 100%. The 1-, 3-, and 5-year actuarial survival rates were 84% ,50% and 29%, respectively, with a median survival time of 37.0 months. The 1-, 3-, and 5-year local control rates were 83% ,63% and 55% ,respectively. The 1-, 3-, and 5-year disease free survival rates were 83% ,49% and 28%, respectively. The 1-, 3-, and 5-year metastasis free survival rates were 84%,51% and 28%, respectively. There were significant influence on the prognosis of age, the state of food taken before treatment, the pain of chest and back, the disease region, the tumor length in x-ray, the maximuminfiltration depth in CT scan, the preliminary curative effect and the no operation in univariate analysis. The Cox multivariate model showed that age, the pain of chest and back, the disease region and the tumor length in X-ray were independent prognostic factors. In the operation group, 80,46 and 16 cases were followed up for at least 1-,3-,and 5-year, respectively. Follow-up rate was 100%. The 1-, 3-, and 5-year actuarial survival rates were 86% ,62% and 41%, respectively, with a median survival time of 47.8 months. Conclusion Three-dimensional conformal radiotherapy is one of the best radiation treatment regimen for early esophageal carcinoma.

Objective To evaluate clinical factors as predictors of radiation pneumonitis(RP)in advanced stage non-small cell lung cancer(NSCLC)patients treated with concurrent radiochemotherapy when gross tumor volume is 70 Gy. Methods Data of 84 patients with histologically proved NSCLC treated with 3DCRT or IMRT were collected. To evaluate the correlation between clinical parameters and radiation pneumonitis(RP). The clinical parameters were considered: pathological type, therapy agents, age,gender, stage, karnofsky performance status(KPS), smoking status, diabetes, chronic obstructive pulmonary disease(COPD). Results The occurrence of grade 1,2 RP was 63%, 33%, respectively. In univariate analysis, diabetes was significantly associated with RP of ≥ grade 1(x2 =4.03, P = 0.045)and ≥grade 2(x2 = 15.59 ,P =0.000). KPS was significantly associated with RP of ≥grade 1(x2 =3.98 ,P = 0.046)and ≥grade 2(x2 = 5.21, P = 0.023). In logistic multivariate analysis, diabetes was significantly associated with RP of ≥grade 1(x2 =5.50,P =0.019)and ≥grade 2(x2 = 12.92,P =0.000). KPS was significantly associated with RP of ≥ grade 1(x2 = 6.29, P = 0.012)and ≥ grade 2(x2 = 6.61, P =0.010). Conclusion The definite statistical significant risk factors of RP are diabetes and KPS.