The purpose of the experiment was to investigate the changes of malondialdehyde (MDA) level and morphological changes in ventricular myoeardium in burnt rats. The results showed that the pathological changes of ventricular myocardium were characterized by its being presented early, severity and multiple patterns; the pathological changes underwent a dynamic course, which could be roughly divided into three phases: the early phase, aggravative phaes and recovery phase of the injury; oxygen-derived free radicies might be a participant in injuring ventricular myocardium according to the experiment.

Background and purpose:There is controversial about dissecting the laryngeal nerve in operation of thyroid tumour in clinic. We adopted the methods of exposure of recurrent laryngeal nerve(RLN) to study their deficiencies and benefits. Methods:We reviewed review 456 cases of thyroid tumour who were operated. In 266 cases, RLN was unveiled generally. In 190 cases that RLN was not exposed, had subtotal thyroidectomy with protection of amatomical region.Results:RLN injury did not occur in the exposure group. 4 cases occurred in non-exposure group(3 cases of temporary RLN injury and 1 case of permanent RLN injury). Among the 3 cases of temporary RLN injury, one was caused by the large size of tumour, the other two were caused by the location of thyroid tumor. One case of permanent RLN injury was a case of reoperation for recurrence.Conclusions:The familiarity of the anatomy and variation of RLN, and the exposure of RLN in thyroid operation, can reduce the rate of the RLN injury.

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 develop an automatic algorithm to predict the dose-volume histogram (DVH) and implement it in clinical practice.Methods Based on the prior information in the existing plan,such as dosimetric results of organs at risk (OARs) and OAR-target spatial relationship,a two-dimensional kernel density estimation was implemented to predict the DVH of OARs.The predicted DVH curves were converted into objective functions that would be implemented in the Pinnacle treatment planning system.Comparisons between predicted and actual values and between Auto-plan and manual planning were made by paired t test.Results We applied this algorithm to 10 rectal cancer patients,10 breast cancer patients,and 10 nasopharyngeal carcinoma patients.The predicted DVH of OARs showed that the deviation between the actual and predicted values at important clinical dose points were within 5%(P>0.05).The re-planning for the 10 breast cancer patients using Auto-plan showed that the heart dose was significantly reduced and the target coverage was increased,which was consistent with the predicted results.Conclusions The method proposed in this study allows for accurat DVH prediction,and,combined with Auto-plan,can be used to generate clinically accepted treatment plans.

Radiomics is a new area of research, which converts imaging data into high?resolution quantitative imaging features by applying the automatic high?throughput imaging?feature?extraction algorithm. With the development of data science, more and more attention has been paid to the non?invasive and quantitative method in precision radiotherapy all over the world. This paper will briefly introduce the concept of radiomics and its application in precision radiotherapy.

Objective To investigate the accuracy of image registration with computed tomograpby (CT) and magnetic resonance imaging(MRI) and to determine gross tumor volume(GTV) of hepatocellular carcinoma(HCC).Methods Thirteen patients were enrolled in this study.CT image was taken in inhala tion phase,and MRIT2 image at the time of peak exhalation.Additional MRIT2 image was taken by fast scanning(MRIT2F) in peak inhalation phase in 6 patients.After mutual information method to CT/MRI im age registration,manual adjustment was made to optimize the accuracy of image fusion.The GTV and liver of each patient was independently contoured by two observers on CT,MRIT2 and MRIT2F images.The accura oy of image fusion was assessed by the ratio of liver overlap(P-LIVERCT-MRIAT2 ,P-LIVERCT-MRIT2F) ,and the dis tance between bone markers(DCT-MRIT2,DCT-MRIT2F) of CT and MRI on the fused image.The volumes of GTV contoured on CT (V-GTVCT),MRIT2 (V-GTVMRIT2),MRIT2F (V-GTVMRIT2F) and their overlap (V GTVCT-MRIT2,V-GTVCT-MRIT2F) and composite volumes (V-GTVCT+MRIT2,V-GTVCT+MRIT2F)were measured.The percentage of V-GTVCT and V-GTVMRIT2 on V-GTVCT+MRIT2,V-GTVCT and V-GTVMRIT2F on V-GTVCT+MRIT2F,V GTVCTMRIT2 and V-GTVCT-MRIT2F on V-GTVCT was also calculated,respectively.Results The mean DCT-MRIT2 and DCT-MRIT2F were 2.7±0.8 mm and 2.1Q±0.9mm.The mean P-LIVERCT-MRIT2 and P-LIVERCT-MRIT2F were 85.9% ± 4.1% and 92.7%± 1.5%.Interobserver difference was significant for GIN defined by CT,but not by MRIT2.V-GTVCT,V-GTVMRIT2 and V-GTVMRIT2F were 387±396 cm3 ,488 ±461 cm3 and 597 ±541 cm3 ,respectively.The percentage of V-GTVCT and V-GTVMRIT2 on V-GTVCT+MRIT2 was 66.2%±13.5% and 88.7% ± 10.2% ,while V-GTVCT and V-GTVMRIT2F on V-GTVCT-MRIT2F was 71.3%±12.7% and 93.5%± 4.8%,respectively.Conclusions CT and MRI for image fusion should be obtained in the same respirato ry phase and in the same treatment position.Automatic registration using mutual information method by auto matic registration software is useful.CT and MRI image should be integrated for HCC GTV delineation.GTV used for planning should be the sum of CT-defined GTV and MRl-defined GTV.

Charged particle therapy offers a better effect and obvious dosimetric and biological advantages over conventional radiotherapy in tumor control.Charged particles form Bragg peak in the dose distribution in tissue, enable most of energy to be deposited in the target region, and thus enhance tumor control and reduce the damage to normal tissues surrounding the tumor.With the increasing demand for charged particle therapy and the advances in particle accelerator, particle therapy technology is developing rapidly.The core apparatus of particle therapy facility is particle accelerator, and the accelerator type, particle type, and implementation technique determine the performance and therapeutic effect of the facility.This article provides a detailed comparative analysis of various particle therapies.Statistical data show that proton therapy is dominant in particle therapy, and high construction difficulty, large facility size, and extremely high cost have limited the development of heavy ion therapy.Nowadays, there are still some technical problems regarding charged particle therapy, and more clinical trials are required.

Objective The positron generated at the dose deposition site by using high-energy carbon ions to hit the material annihilate with the negative electron in the material to release the gamma photon.The positron-emitting isotope (PEI) distributions in the target volume are activated significantly by carbon ions.Therefore, the mean values of positron emission tomography (PET) activity could be related to the delivered doses to the clinical target volume from carbon ion.This specialty can be used for the image registration fusion of the carbon ion treatment planning computed tomography (CT) and treatment verification PET-CT.After radiation in the almost same decay period, the relationship between the different target volume and the PET-CT SUV of different every single fraction dose can be found, then the range of SUV for the radiation target could be decided.So this PET-CT standardized uptake value (SUV) range can also provide a reference for the correlation and consistency in planning target dose verification and evaluation for the clinical trial.Methods The head phantom was used as a simulation of the real human body, the 1 cc, 4 cc, and 10 cc cube volume target contouring were done in the TPS, the 90 degree fixed carbon ion beams were delivered in different single fraction effective dose of 2.5 GyE, 5 GyE, and 8 GyE.After the beam delivery, later the PET-CT scanning was performed and parameters of scanning followed the trial regulation.The MIM Maestro software was used for the image processing and fusion to determine the maximum, minimum, average, and total values of SUV in the virtual clinical target volumes for the different single fraction dose.Results The results showed that for the same target volume, the SUV range of target had an approximate linear correlation with effective dose of target (P=0.000).The same effective dose for the different target volumes got the same SUV range (P>0.05).Conclusions For the carbon ion treatment plan, the SUV range from image registration and fusion of planning CT and PET-CT after treatment can be used to make an evaluation for accuracy of the dose distribution.And this method also could be used in the hyper-fraction treatment plan.In the SUV range research of different decay periods, the similar method can be performed for the exploration.

Objective To develop a practical image acquisition strategy using intermittent breath?hold cone beam computed tomography (CBCT). Methods A breathing phantom was used to simulate the movement of tumor near the diaphragm during free breathing and breath hold and scanned by conventional breath?hold CBCT and type Ⅰ/Ⅱ intermittent breath?hold CBCT. In the conventional breath?hold CBCT, scan paused and free breathing occurred at the break of breath hold and free breathing was not included in the scan. In the intermittent breath?hold CBCT, one scan covered several breath holds separated by free breathing in a ratio of 3 vs1. Image quality and three?dimensional registration accuracy were quantitatively compared between conventional breath?hold CBCT and type Ⅰ/Ⅱ intermittent breath?hold CBCT. Comparison of image quality parameters between conventional breath?hold CBCT and intermittent breath?hold CBCT was made by paired t test. Results Motion artifacts arose in type I and Ⅱ intermittent breath?hold CBCT scans. There were no significant differences in the reconstructed pixel value or uniformity between intermittent breath?hold CBCT and conventional breath?hold CBCT ( P>0. 05, and P= 0. 02, 0. 53 ) . Compared with conventional breath?hold CBCT images, the signal?to?noise ratios of type I andⅡintermittent breath?hold CBCT images were reduced by 30% and 60%, respectively ( P<0. 05 ) . The registration error was up to 0 . 4 cm in the anterior?posterior direction and less than 0 . 1 cm in other directions . Conclusions The phantom study shows that intermittent breath?hold CBCT does not significantly reduce image quality or registration accuracy compared with conventional breath?hold CBCT. The feasibility of intermittent breath?hold CBCT in clinical application needs to be further validated among a large number of patients.

Background and purpose:The radiation should move at the same direction in accordance with the position of the couch during radiotherapy due to the different location of gross target volume. However, under the condition of the long distance movement of the couch, collisions between the gantry and the couch (or the patients) may happen. To avoid the collisions between the gantry and the couch, the motion area conlfiction between the gantry and the couch was analyzed.Methods:The distance from isocenter to the surface center of linear accelerator head, and the width and the thickness of treatment bed were measured when the treatment bed was empty, and gantry and collimator were at zero position. Forty sets of bed movement data were collected. The sum of squares ofX-andY-coordinates of reference point was calculated and compared with squares of rotation radius. Then, it was anticipated whether the linear accelerator head will collide with treatment bed. Finally, practical veriifcation was made.Results:Whether linear accelerator head collides with treatment bed depends on the difference between the sum of squares ofX-andY-coordinates and the squares of rotation radius. No collisions will happen when the sum of squares ofX-andY-coordinates is less than that of the squares of rotation radius.Conclusion:It is feasible to avoid collisions of linear accelerator head with treatment bed by comparing the sum of squares ofX-andY-coordinates of reference point with squares of rotation radius.