Objective To study anti-radiation behavior of plasma sprayed boron carbide coatings. Methods The anti-radiation capacity of 16Mn steel which was coated with 0.1 mm plasma sprayed boron carbide were studied. The irradiation beams were 6,10,15 MY X-ray and 6,9,12,15 MeV electron emitted by accelerator, X-ray emitted by 60Co machine,fast neutron, and X-ray emitted by kilovoltage X-ray ma-chine. Results Anti-radiation capacity of plasma sprayed boron carbide coatings was not found for X-ray beams emitted by accelerator and 60Co machine. For electron beams,the anti-radiation capacity were found. The deeper of location, the stronger was anti-radiation. However, the anti-radiation capacity was not good. For fast neutron,the anti-radiation capacity was good. For X-ray emitted by kilovoltage X-ray machine,the anti-radiation was good,and only 0.1 nun plasma sprayed boron carbide had 15% attenuation. Conclusions The plasma sprayed boron carbide coatings have the anti-radiation capacity for X-ray emitted by kilovoltage X-ray machine in medical field.

Background and purpose:Indensity modulated radiotherapy(IMRT) is an advanced method in radiotherapy field.Divect machine optimization technique is an good aritmetic for IMRT optimization.The purpose of this study was to compare the dosimetric differences between traditional technique and direct machine parameter optimization(DMPO) technique in the treatment of nasopharyngeal carcinoma(NPC) using step and shoot IMRT.Methods:Eleven patients of(NPC) were treated with step and shoot IMRT in Cancer Hospital,Fudan University from Feb.2005 to May 2006.Their plans(original plan,defined as treat) were archived for comparing with four kinds of IMRT plans(defined as DMPO100,DMPO90,DMPO80,DMPO70) with different predefined maximum number of segments(100,90,80,70,respectively),which were designed to use direct machine parameter optimization(DMPO) technique.We compared the total monitor units(MU),total segments,dose distribution and conformity index among the plans.Results:All the plans showed similar target coverage.Compared with traditional technique,IMRT plans with DMPO technique showed higher conformity index,and had similar uniformity except plan DMPO70.The dose distributions of DMPO100 and DMPO90 were similar or superior to the original plan(treat) in terms of critical organs.Without sacrificing plan quality,the total segments were about half of traditional plan if DMPO technique was used for planning.Moreover,the total monitor units(MUs) and the radiation time were decreased.Conclusions:Compared with traditional technique,plans designed with DMPO technique show sharp decrease in total segments without sacrificing plans quality in the treatment of nasopharyngeal carcinoma(NPC).The DMPO technique can also decrease the total MUs and radiation time.

Objective To investigate the advantage of the intensity-modulated radiotherapy treatment (IMRT) by allowing dose heterogeneity in the target volume in esophageal cancer treatment planning.Methods Two sets of 5-field IMRT planning were designed for 10 esophageal cancer patients upon the condition of appropriate clinical tolerance level with the prescription dose of 60 Gy to 95% of the planned target volume (PTV) and the maximum dose of 45 Gy to the spinal cord:the IMRT with rigid restriction of the maximum homogeneous dose to the PTV within 63 Gy prescribing a homogeneous dose ( IMRThom ) and the IMRT allowing dose heterogeneity by loosening the constraints on maximum dose in the PTV to 69 Gy ( IMRTinhom ).Dosimetric comparison was conducted by using dose-volume histograms.Results Compared to IMRThom, the minimum dose (t = -3.37,P =0.012), maximum dose (t = - 23.58,P = 0.000), mean dose ( t = - 4.95, P = 0.002 ), and heterogeneity index ( t = - 11.06, P =0.000) in PTV of the IMRTinhom were all significantly increased, and the values of V5 (t = 6.96, P =0.000), V10(t=5.24,P=0.001) , V15(t=4.73,P=0.002) , V20(t=8.08,P=0.000) , V25(t=8.58,P = 0.000), and mean dose (t = 7.28,P = 0.000) of the normal lungs were all significantly lower.There were no significant differences in all the indexes for the mean dose to the heart and maximum dose to the spinal cord between these 2 set of planning.Conclusions The IMRT plan allowing dose heterogeneity in the PTV escalates the prescription dose and decreases the doses to the lungs.

Objective To quantitatively evaluate the image quality, stability and volume precision in kilovoltage cone beam CT (CBCT) on Varian linear accelerator. Methods The Catphan (R) 600 phantom was repeatedly scanned in the full-fan and half-fan CBCT scanning modes. A simulation fan-beam CT (FBCT) was used as a benchmark and results related to the low contrast resolution, spatial resolution,uniformity and image noise were compared with the CBCT using the treatment planning system. The comparison of image quality and long-term stability and volume precision was analyzed. Results Spatial resolution was no differences observed between FBCT and CBCT ( 6 lp/cm: 6 lp/cm , T = 18. 00 , P＞ 0. 05 ) .Low contrast resolution was, on average, 1. 65％ and 1. 74％ for both CBCTFull-Fan and CBCTHalf-Fan , and 1. 03％ for the FBCT ( T =6. 00, P ＜ 0. 05). Uniformity was, on average, 0. 005 and 0. 033 for both, and 0. 003 for the FBCT ( T=6. 00 , P ＜0. 05). In terms of image noise, the FBCT images were superior to the CBCT (T=30. 00, P＜O. 05). In valid scan range of the CBCT, reconstructed precision was high. There was no significant time trend in the image quality. Conclusions The image quality of kilovoltage CBCT is inferior to the conventional CT. However, tumor and soft tissues are visible in the CBCT images. The image stability and reconstructed precision is satisfying.

Objective To compare the difference region of interest volume (ROI) calculation method between Pinnacle and Eclipse treatment planning system. Methods To acquire CT image with 3 of slice thickness (1 mm, 3 mm, and 5 mm). Delineate 1, 2 and 5 slices square and circle contours in Pinnacle treatment planning system. Meanwhile 15 cases that include 5 cases with head neck tumor, 5 with thorax tumor and 5 with abdomen tumor were selected. Those image and ROI were transfer to Eclipse treatment plan system by DICOM RT protocol . The ROI volume was compared between two TPS . Results For ROI with small volume, the volume difference between TPS was obvious (for small volume ROI have 12 times difference, for big volume ROI almost same). The volume difference between TPS was influenced by many factors. The number of ROI slice and the magnitude of ROI was related with the difference between TPS (R2 = 1. 000, P = 0. 000). The CT thickness (R2 = 0. 200, P = 0. 972 ) and the shape of ROI ( R2 =0. 200, P = 0. 089) were not significant factors. The center of ROI on different axis was not affect the volume calculation in Pinnacle, which cause 3% different in Eclipse. The CT thickness was proportional to the ROI volume ( Pinnacle R2 = 0. 548, P = 0. 011; Eclipse R2 = 0. 502, P = 0. 027 ). In clinical case, optic chiasm and Len averagely have more than 35% volume difference between those two TPS. Conclusions We should pay more attention about the difference volume calculation algorithm between Pinnacle and Eclipse,especially when transfer small volume ROI to another TPS, which may have significant difference.

AIM:To investigate the role of p38 MAPK/ATF-2 pathway in C-relative protein ( CRP)-induced endothelial cell activation.METHODS:Human coronary artery endothelial cells ( HCAEC) were cultured and were used between passages 3 and 7.CRP served as a stimulus for endothelial cell activation.Western blotting was performed to de-termine the expression and phosphorylation of eNOS, p38 and ATF2.ELISA was carried out to detect the levels of ICAM-1, VCAM-1 and MCP-1 released from HCAEC.Pharmacological p38 inhibitors SB203580 and SB202190 were used to de-termine the effect of p38/ATF-2 pathway.RESULTS:CRP reduced the p-eNOS level in a concentration-dependent man-ner and induced the release of ICAM-1, VCAM-1 and MCP-1.The p38/ATF-2 pathway was activated by CRP treatment. SB203580 and SB202190 partially rescued p-eNOS level and suppressed the secretion of ICAM-1, VCAM-1 and MCP-1. CONCLUSION:p38MAPK/ATF-2 pathway participates in CRP-induced endothelial activation.

Objective To monitor the performance constancy of the HS-126E automatic X-ray film processor and to investigate the effects of chemical processing time on the reproducibility of film dosimetry.Methods With films having identical exposure,15 ready-pack Kodak X-omat-V films from the same batch were divided into 5 groups and exposed one by one under the identical conditions.One group of test film was processed per day from Monday to Friday with identical temperature and time.All films were digitized with a Vidar VXR-16 bit film digitizer. The average optical density(A) at irradiation field center was analyzed with RIT113 film dosimetry system software.At the same time,another 10 films in 5 groups from the same batch were exposed with vertical method and processed to get the calibration data and sensitometric curves.The film sensitivities,i.e.,ratio of A to delivered dose,were calculated and compared between groups.Another 15 films in 5 groups were exposed with horizontal method and processed similarly to the test films,the point dose at 1.5?cm depth on the central axis was calculated with sensitometric curve and compared with the value measured by ion chamber.Results Variations of A value in each group was less than 2%.During the processing period,a trend of decrease along with time in mean A value decreased day by day was observed.Both the standard deviations and coefficients of variation in all groups were within 2%.One-way ANOVA showed that there was a significant difference of the mean A value among all films from Monday to Friday(P

Objective To calibrate and assess the dose distribution of 125 I seed brachytherapy. Methods Twenty 125 I seeds, each with activity of 12.2 MBq, were implanted on the circumference of a circle 15mm across in a phantom. Into a designed prostate model, 70 125 I seeds were implanted in four planes. The absorbed dose rate of the target volume was monitored by Farmar 2570 dosimeter and thermoluminescence dosimeters (TLD) with the isodose curves drawn on Kodak films. Results The central dose rates of the circular target volume assessed by Farmar 2570 and TLD were 8.4, 7.9 cGy/h in the phantom and 12.0, 11.1 cGy/h in the prostate model. For the target volume of the prostate model, the total absorbed dose was 24?219 cGy. The dose rate 4 cm from the prostate cancer as shown by the isodose curves was only 10% of the central dose rate. Conclusion The central dose rate of target volume measured by the two methods are similar.

7000?cGy). The cumulative incidence of cranial nerve Ⅸ-Ⅻ palsies increased in patients with advanced N stage. Patients in the first group of treatment field had the highest risk to progress cranial nerve Ⅸ-Ⅻ palsies, followed by the second group, and the third group had the lowest risk. Only 1 in 34 patients with brachytherapy developed cranial nerve palsy. Conclusions Our retrospective data show that the radiation-induced cranial nerve palsy is a common complication in NPC patients after radiotherapy and the incidence seems to increase with the duration of the follow-up. Factors that potentially affect the injury of cranial nerve Ⅰ-Ⅶ and Ⅸ-Ⅻ are different, because of the different anatomy. Controlling the doses to the nasopharyngeal region and using faciocervical fields may help to lower the incidence of cranial nerve palsy.

Objective To evaluate the feasibility and accuracy of performing dose calculation on megavoltage cone-beam CT(MVCBCT) in the head and neck. Methods MiniCTQC phantom was imaged using MVCBCT scanner, and the MVCBCT value density calibration curve was established. Conventional CT and MVCBCT image of phantom and nasopharyngeal carcinoma(NPC) patient were acquired respectively. Two kinds of single field plan were designed for conventional CT image of phantom,and IMRT plan was used for conventional CT image of a NPC patient. The conventional CT plans were copied to MVCBCT image. The dose distribution was calculated for targets and normal tissues using the MVCBCT value density calibration curve,and compared with that of conventional CT. Results For all the cases,the differences between the calculated dose distributions using MVCBCT and CT were less than 3% and 3 mm in single field plan. In IMRT plan, DVHs of conventional CT and MVCBCT were in excellent agreement. The biggest difference between conventional CT and MVCBCT was 95 cGy with the error of 1.4%. On the isocenter plane,the passing rate was 95.5% ,99.4% ,93.8% ,98.7%, 100% ,94.5% ,97.3% ,95.6% ,99.3% and 99.4% for the beam angle of 0°,45°,90°,120°,160°,200°,240°,280° and 320°. Conclusions Performing dose calculation using MVCBCT in head-and-neck region was feasible, and the dose distributions on the conventional CT and MVCBCT were in excellent agreement.