Objective To investigate the accuracy and reliability of the image automatic matching using X-ray volumetric image (ⅩⅥ) system with the accelerator Elekta Synergy and to compare the matches with different methods and area.Methods A simulation plan using the head and neck phantom was designed and sent to ⅩⅥ system for CBCT scanning.During the scanning,the couch for certain distance was moved and the data of ⅩⅥ image automatic Matching in different matching methods and area was collected.Results The result of ⅩⅥ image automatic matching is consistent and correct to direction and distance which the couch had been moved (x:(0.11 ± 0.41) mm,y:(-0.04± 2.6) mm,z:(0.28 ± 0.74 mm)).There are not significant differences between the results that matching in different matching methods and different matching area.Conclusions The automatic image Matching of ⅩⅥ is accuracy and high reliability in recognition of offset error.But there are some significant differences on the automatic image Matching in different matching methods and different matching area.

Objective:To investigate the effect of body mass index (BMI) on setup errors in intensity-modulated radiotherapy for cervical cancer and explore the optimal position for patients with different BMI without taking into account the rotation error and the changes in target area and adjacent organs.Methods:A total of 90 patients were divided into three groups according to their BMI: light weight group (BMI≤18.4 kg/m 2), normal weight group (18.5 kg/m 2≤BMI≤23.9 kg/m 2) and overweight group (BMI≥24 kg/m 2). Thirty patients were assigned into each group including15 patients in the supine position and 15 patients in the prone position. In total, 2 250 sets of CBCT scan data of 90 patients were obtained. The setup errors were recorded and analyzed in each group. The margins of the optimal position were calculated according to the formula of M PTV=2.5+ 0.7. Results:When BMI was not taken into account, there was no significant difference in the setup errors between the supine and prone positions in the x, y and z directions (all P>0.05). When BMI was considered, the setup error in the supine position were significantly smaller than those in the prone position in the x and y directions in the light weight group, whereas there was no significant difference in the setup errors between the supine and prone positions in the z direction ( P>0.05). The corresponding M PTV in the supine position was 4.76, 4.27 and 5.73 mm, respectively. In the normal weight group, there was no significant difference in the setup errors between the supine and prone positions in the x and y directions (both P>0.05), whereas the setup error in the prone position was smaller than that in the supine position in the z direction. The corresponding M PTV in the prone position were 6.42, 10.21 and 4.91 mm, respectively. In the overweight group, there was no significant difference in the setup errors between the supine and prone positions in the x and z directions (all P>0.05), whereas the setup error in the prone position was smaller than that in the supine position in the y direction. The corresponding M PTV in the prone position were 5.88, 5.26 and 5.32 mm, respectively. Conclusions:Without taking into account the rotation error and the changes in target area and adjacent organs, when the BMI≤18.4, the supine position is recommended. When the BMI≥18.5, it is better to choose the prone position.

Objective To investigate the positioning errors of head and neck during intensity-modulated radiation therapy of nasopharyngeal carcinoma.Methods Nineteen patients with middle-advanced nasopharyngeal carcinoma (T2-4N1-3M0), treated by intensity-modulated radiation therapy, underwent repeated CT during their 6-week treatment course.All the patients were immobilized by head-neck-shoulder thermoplastic mask.We evaluated their anatomic landmark coordinated in a total of 66 repeated CT data sets and respective x, y, z shifts relative to their position in the planning CT.ResultsThe positioning error of the neck was 2.44 mm±2.24 mm,2.05 mm±1.42 mm,1.83 mm±1.53 mm in x, y, z respectively.And that of the head was 1.05 mm±0.87 mm,1.23 mm±1.05 mm,1.17 mm±1.55 mm respectively.The positioning error between neck and head have respectively statistical difference (t=-6.58,-5.28,-3.42,P=0.000,0.000,0.001).The system error of the neck was 2.33,1.67 and 1.56 higher than that of the head, respectively in left-right, vertical and head-foot directions;and the random error of neck was 2.57,1.34 and 0.99 higher than that of head respectively.Conclusions In the process of the intensity-modulated radiation therapy of nasopharyngeal carcinoma, with the immobilization by head-neck-shoulder thermoplastic mask, the positioning error of neck is higher than that of head.

Objective To investigate an appropriate megavoltage computed tomography ( MVCT ) protocol to guide helical tomotherapy ( HT) for multiple metastases. Methods According to the location of target volume, 48 patients with multiple metastases undergoing HT were divided into head/chest group ( n=15), head/pelvis group (n=15), and chest/pelvis group (n=18). Each target volume received MVCT scans during the treatment. The obtained MVCT images were registered to CT images and the setup errors were recorded. The CTV?PTV margins were calculated. Comparison was made by paired t test. Results In the head/chest group, there was no significant difference in the setup error in x?axis between the head and chest (-0.15±1?25 vs. -0.21±2?34, P=0?71), while the head had significantly smaller setup errors in y?and z?axis than the chest (0.73±1?22 vs. 1.56±2?54, P=0?00;0.93±1?44 vs. 2.65±1?88, P=0?00). In the head/pelvis group, the head had significantly smaller setup errors in x?, y?, and z?axis than the pelvis (-0.16±1?31 vs. -1.29±3?72, P=0?00;0.81±1?34 vs. 3.20±3?90, P=0?00;1.24±1?75 vs. 5.49±2?80, P=0?00) . In the chest/pelvis group, there were no significant differences in setup errors in x?or y?axis between the chest and pelvis (-0.25± 2?90 vs. -0.22± 3?65, P=0?06;0.35± 3?60 vs. 0.38± 3?78, P=0?87), while the chest had a significantly smaller setup error in z?axis than the pelvis (1.95±2?81 vs. 3.35± 3?05, P=0?00) . In the three groups, the CTV?PTV margins of lower target volume were reduced in three dimensions after the correction of upper target volume, in which y?axis showed the largest reduction of CTV?PTV margins (5?13 vs. 4?01;9?17 vs. 8?30;8?52 vs. 7?13). Conclusions The setup error of individual target volume should not be used for correction of the overall setup error in HT for multiple metastases with isolated target volume. An MVCT protocol that provides image?based guidance for multiple target volumes is recommended.

Objective To compare the setup errors of the negative pressure vacuum air cushion (vacuum bag) and the Orfit body foam fixator (Orfit frame) in radiotherapy for cervical cancer.Methods A total of 40 patients receiving three-dimensional radiotherapy for cervical cancer were enrolled in this study and equally and randomly divided into vacuum bag group and Orfit frame group.And the two groups were divided into Orfit-1 group, Orfit-2 group, vacuum-1 group, and vacuum-2 group according to the treatment course.The Orfit-1 group and vacuum-1 group were the data in the first 12 treatments, while the Orfit-2 group and vacuum-2 group were the data in the following 13 treatments.A cone-beam computed tomography scan was performed before each treatment to analyze setup error and then the body position was corrected to start the treatment.Comparison of continuous data between groups was made by paired t-test, while comparison of categorical data was made by chi-square test.Results There was a significant difference in the setup error in y-axis direction between the Orfit-1 group and the Orfit-2 group (P=0.003) and the setup error in r-axis direction between the vacuum-1 group and the vacuum-2 group (P=0.013).There were no significant differences in the setup errors in four directions (x-axis, y-axis, z-axis, and r-axis) between the Orfit-1 group and the vacuum-1 group (P>0.05).There were significant differences in the setup errors in y-axis and z-axis directions between the Orfit-2 group and the vacuum-2 group (P=0.007;P=0.001).Conclusions The Orfit frame and the vacuum bag have their own advantages and disadvantages in the fixation of body position in radiotherapy for cervical cancer.The setup error can be improved by long vacuum bags, ultrasound bladder capacity scanner, image-guided radiotherapy, or sectional radiotherapy plan.

Purpose: Simulating calculation the dose distribution of the total body irradiation (TBI) with three dimension treatment planning system(3D-TPS ). Materials and Methods: For TBI, the source skin distance(SSD) is 380 cm, field size is 40 cm × 40cm, and collimator angle is 45°. The percent dose depth (PDD) and onset axis ratio (OAR) of the linac accelerator is measured with the big water phantom self-made. In the same radiation condition, the PDD and OAR of water which is simulated calculation with the 3D-TPS is compared with the measurement results to confirm whether the 3D-TPS can calculate the TBI dose distribution. The dose distribution of the human phantom is calculated with 3D-TPS, which is compared and confirmed with the film and TLD measurements. Results: The maximum error of PDD and OAR in the water phantom between the measurements and calculations of 3D-TPS are 3% and 6%. The calculation results of the 3D-TPS is according with the measurement results of the film and TLD approximately. Conclusions: 3D-TPS could simulate calculation the dose distribution for TBI accurately. It is possible to improve more uniform dose for TBI with corresponding compensator for specific patient.

Objective To introduce a new way to solve the problem of field-field junction in the traditional radiotherapy of the nasopharyngeal carcinoma better.Methods Using the 3-dimentional planning system,the dose distribution of traditional radiotherapy and the electronic beam irradiation technology of L shape field for nasopharyngeal carcinoma in 2D-or 3D-CRT could be gotten.Results The dose coverage of V95 of the gross tumor volume(GTV)satisfied the clinical requirements.The highest dose in the electronic beam irradiation of L shape field was 7200 cGy,while it was 8900 cGy in the traditional way.The volume of dose that over 6500 cGy of throat was 19.64 ％ in the former,the latter was 31.95 ％.Conclusion The electronic beam irradiation technology of L shape field is better than the traditional radiotherapy in field-field junction and in dose distribution.Since that,the electronic beam irradiation technology of L shape field is worth of application for the treatment of nasopharyngeal carcinoma.

Objective:Before the radiotherapy was performed, patients with pelvic tumors were analyzed for the consistency of bladder filling in the three steps of " Immobilization" , " CT Simulation" and " X-ray Simulation" .Methods:In 2014, 105 patients (68 cases of cervical cancer, 32 cases of rectal cancer, 3 cases of vaginal cancer and 2 cases of prostate cancer) with pelvic tumor radiotherapy were randomly assigned to monitor bladder urine volume to a target urine volume of 400 ml. First, patient were exhorted to empty the bladder, and the bladder volume meter BVI 9400 was used to measure the urine volume of the patient after emptying of the bladder. The patient immediately drank about 540 ml of water and suppressed urine, measurements were taken every 0.5 h. At the same time, when the patient complained of " urgency of urine" , bladder urine volume would be measured again and the time would also be recorded. Every other half an hour (emptying, 0.5 h after emptying, 1.0 h after emptying), when complaining of " urgency of urine" , when actually performing urine volume and time were described as: U 0 and t 0, U 0.5 and t 0.5, U 1.0 and t 1.0, U t and t, U T and T. Results:There was a statistically significant difference in gender and age, and women had stronger ability to urinate than men U 1.0( P=0.003), young people had stronger ability to urinate than middle-aged U 1.0( P=0.002). In the three-step comparison, there was no statistically difference between 1 hour after emptying urine volume U 1.0( P=0.177) and the actually performing urine volume U T ( P=0.052). And the final urine volume was concentrated at 298-526 ml. After the patient emptied the urine volume and complained of " urgency of urine" , the time slot was t=(75.2±49.9) min, with the urine volume of U t=(331.2±140.3) ml. And there was no statistically difference between U t and U T ( P=0.198) at X-ray Simulation. Conclusions:The patient emptied the bladder and immediately drank 540 ml of water. After 1 hour of suppressing urine, he complained of " urgency of urine" and achieved the target urine volume (400 ml). At this time, the bladder urine volume U 1.0 was consistency in the immobilization, CT Simulation, and X-ray Simulation.

[Objective] To establish an effective and stable method to induce hematopoietic cells from embryonic stem(ES) cells,the phenotype and function of ES-derived hematopoietic cells induced by stromal cell conditioned medium (SCCM) of yolk sac (YS),fetal liver (FL) or bone marrow (BM) were analyzed and compared.[Methods] 10% of YS-SCCM,FL-SCCM or BM-SCCM was added to culture system for differentiation of ES cells.Flow cytometric analysis was used to identify expression of Flk1,Integrin α4,Sca-1,and CD34.Colony analysis was used to identify the quantity of high proliferative potential colony-forming cells (HPP-CFC) in differentiated ES cells.The yield of CFU-S (colony-forming unit-spleen) was also analyzed by transplanting ES cell derivatives into lethally irradiated mice.[Results] Expression of Flk1,Integrin α4,Sca-1,and CD34 could be tested on induced EB cells.The percentage of Flk-1+,Integrin α4+ and Sca-1+ cells induced by were 3.03%,2.9%,and 13.74%,respectively,which are greater than other groups.The percentage of CD34+ cells induced by BMSC-CM was 1.07% which was greater than other groups.The yields of HPP-CFC from hematopoietic cells induced by FLSC-CM or BMSC-CM were 7.4 /105 cells (P ＜ 0.01) and 5.8 /105 cells (P ＜ 0.05) which were greater than the yields of control group.The yields of CFU-S from hematopoietic cells induced by FLSC-CM or BMSC-CM were 8.5/5 × 105 cells and 6.75/5 × 105 cells which were also greater than the yields of control group (P ＜ 0.001).[Conclusion] Both YS-SCCM,FL-SCCM,and BM-SCCM could promote hematopoietic differentiation of ESE14.1 cells.Hematopoietic differentiation induced by FL-SCCM or BM-SCCM is more effective,which generates hematopoietic progenitor cells with normal function.Application of FL-SCCM generates more primitive hematopoietic progenitor cells than that of BM-SCCM.

Objective:To investigate the clinical feasibility of the Unity radiotherapy system guided by magnetic resonance imaging.Methods:Twenty-four patients were enrolled and received a total of 384 fractions of treatment at Unity system. According to the treatment site, all patients were divided into head-neck, abdomen-thorax, pelvic, spine and limb groups. The patients were set-up without external laser. And then, the time required at different stages in online treatment process and the registration error of each fraction were separately calculated. The geometric deformations of MR images were weekly measured by using MR geometric deformation phantom. At last, the Arccheck was used to perform the dose verification of reference plan, online plan and offline plan.Results:The mean duration of radiotherapy in the five groups were 29.1, 27.6, 26.6, 25.6 and 32.0 min, respectively. The set-up errors in the left-right, superior-inferior and anterior-posterior direction in the five groups were: head-neck group (0.08±0.06 cm, 0.16±0.13 cm, 0.08±0.05 cm), abdomen-thorax group (0.23±0.18 cm, 0.50±0.47 cm, 0.12±0.1 cm), pelvic group (0.25±0.19 cm, 0.32±0.25 cm, 0.11±0.09 cm), spine group (0.46±0.38 cm, 0.26±0.26 cm, 0.13±0.07 cm) and limb group (0.33±0.30 cm, 0.34±0.23 cm, 0.08±0.06 cm), respectively. In the central region, the geometric deformation of MR was less than 0.3 mm, and that of the sphere with a diameter of 500 mm was less than 2.1 mm. The meanγ pass rate of the reference plan, online plan and offline plan were 97.92%, 97.84% and 94.58%, respectively.Conclusions:MR-guided radiotherapy has great potential for clinical application, whereas the process of Unity system is relatively complex. The synergy of different departments has a great impact on the treatment, which needs further optimization.