Objective To investigate the expansion margins of the planning target volume (PTV) and the planning organ at risk volume (PRV) in nasopharyngeal carcinoma patients immobilized with Styrofoam and head-neck-shoulder mask. Methods A convenient sample of 33 nasopharyngeal carcinoma patients who received radiotherapy at Huanggang Central Hospital from January to October 2024 were selected as the research subjects. All patients underwent cone beam CT scans during the first three treatments and weekly thereafter. After registration and calibration, the setup errors in the X (LAT), Y (LNG), and Z (VRT) directions were recorded. Statistical analysis was performed on the setup errors in each direction to determine differences, and the expansion margins for PTV and PRV were calculated using empirical formulas. Results A total of 229 cone beam CT images were collected. Statistical analysis found that the setup errors (systematic error ± random error) of the patients in the X, Y, and Z directions were 1.05 ± 0.72, 1.30 ± 0.80, and 1.29 ± 0.82 mm, respectively. The expansion margins for PTV in the left-right, superior-inferior, and anterior-posterior directions were 1.40, 1.76, and 1.8 mm, respectively. The expansion margins for PRV in these directions were 0.83, 1.02, and 1.05 mm, respectively. Conclusion For patients immobilized using Styrofoam and head-neck-shoulder mask, it is recommended that the expansion margins for PTV and PRV be set at 2 mm and 1 mm, respectively, in the left-right, superior-inferior, and anterior-posterior directions, and the PRV margin for the spinal cord be set at 3 mm in all directions.

Objective:To observe the feasibility of magnetic resonance (MR)-guided stereotactic body radiotherapy (SBRT) for non-small cell lung cancer, and analyze the dosimetric differences in the presence or absence of magnetic field.Methods:Three patients with non-small cell lung cancer were prospectively treated with MR-guided linac (MR linac) for SBRT, and the dose was calculated with or without magnetic field models. The differences of dose distribution with or without magnetic field models were compared. At the same time, the target coverage, plan pass rate and treatment time were described, and the complexity of the conventional accelerator backup plan and the magnetic field model were compared.Results:The treatment time of 3 patients was (36.67±6.11) min, and the average time of online adaptive planning was (14.4±1.7) min, which was basically tolerated by patients. The treatment plan pass rate (3%/3 mm) was 98.9%, the Gamma pass rate (3%/3 mm) of the online plan during treatment was 98.5% and the target coverage was 99.1%, which met the clinical needs. The dose in the low dose area of the lung was slightly lower than that in the case without magnetic field, whereas the dose in ribs and skin was slightly higher than that in the plan without magnetic field. The number of machine unit (MU) for online adaptive plan was slightly higher than that of the reference plan, and the number of MU for the conventional accelerator standby treatment plan was significantly lower than that of the MR linac plan under the same target coverage. The follow-up results showed that there was no adverse reaction, and the short-term efficacy was partially relieved.Conclusions:In the case of considering the influence of magnetic field, the treatment plan meeting the clinical needs can be obtained. It is proven that SBRT radiotherapy for lung cancer guided by magnetic resonance accelerator is feasible, whereas the treatment time and process are complex.

Objective:To compare the performance and surgical outcomes of disposable digital flexible ureteroscope with a reusable fiberoptic flexible ureteroscope in treatment of upper urinary stones.Methods:A prospective, multicenter, single-blind and randomized controlled study was performed from April 2018 to December 2018. Eligible patients were randomized, in a ratio of 1∶1, to either experimental group or control group. The inclusion criteria for the study were: aged 18-60 years, solitary upper urinary stone or multiple stones with stone size less than 2 cm, absence of urinary tract infection (UTI) or UTI was controlled, normal liver and renal function. Exclusion criteria included: patients with congenital anomalies, calyceal diverticular stone, IP angle less than 30°, renal insufficiency. pregnancy or lactation, cardiopulmonary function abnormality and coagulation abnormalities. Patients in experimental group received ureteroscopy through a disposable digital flexible ureteroscope (PU3022A, PUSEN), while patients in control group received ureteroscopy through a reusable fiberoptic flexible ureteroscope (Flex-X2, STORZ). The primary endpoint was the high-quality rate of images during the operation. The secondary endpoints included success rate of fragmentation and postoperative complication rates.Results:93 patients were recruited, and 90 of them were finally complete the study (i.e., 45 patients in each group). The demographic and preoperative parameters were comparable between the two groups except the stone size in patients with solitary stone. The high-quality rate of images was significantly higher in experiment group than that in control group (100.0% vs. 15.6%, P<0.001). There were no significant differences in terms of success rate of fragmentation(68.9% vs. 71.1%, P=0.818), hemoglobin dropped (3.91 g/L vs. 3.62 g/L, P=0.880), serum creatinine changed, and postoperative complication rates(6.7% vs.6.7%, P=1.000). Conclusions:Disposable digital flexible ureteroscope achieves similar surgical outcomes to the reusable fiberoptic flexible ureteroscope with a better quality of endoscopic images.

Objective To compare the dosimetric and delivery efficiency between intensity-modulated radiation therapy (IMRT) plans based on Halcyon and Trilogy accelerator.Methods Clinical data of 12 patients with cervical cancer receiving Trilogy platform-based IMRT were retrospectively analyzed.The target area and organ at risk were introduced into the Eclipse version 15.1 TPS.The Halcyon-based IMRT was re-designed.The dose coverage of target area and organs at risk,monitor unit (MU) efficiency,delivery time and segment area and the differences between the proximal and distal segment area were statistically compared between two IMRT plans.Results The Halcyon treatment platform could meet the clinical objectives.Dose distribution of the target area was similar to that of the Trilogy plan (P＞O.05).The volumes in the bladder and rectum receiving 30 Gy and the volumes in the left femoral head receiving 20 Gy of Halcyon plan and the mean dose (D) of bladder,rectum and left femoral head were significantly lower compared with those of the Trilogy plan (P=0.001-0.043).The MUs of the Halcyon plan was 2 316.7± 209.7,significantly higher than 1 692.5± 259.5 of the Trilogy plan (P=0.000).The delivery time significantly differed between the Halcyon [(3.01±0.28) min] and Trilogy [(12.38± 1.49) min] (P=0.000).The average segment area of Halcyon plan for proximal and distal MLC was (43.7±32.5) cm2 and (28.8±25.4) cm2,the average segment area of Trilogy plan was (25.7±16.8) cm2,the ratio of the proximal and distal segment area was 1.73±0.43,ranging from 0.71 to 6.28.Conclusions Halcyon treatment platform can meet the clinical requirements and reduce the dosage coverage of normal tissues with better delivery efficiency.The ratio of proximal and distal segment areas should be considered during the plan design.

Objective To analyze the dosimetric and delivery efficiency differences between IMRT plans based on Halcyon and Trilogy Accelerator for left side breast cancer.Methods A total of 10 patients with left side breast cancer based on the Trilogy platform were retrospectively analyzed.For each patient,plan based on Halcyon was redesigned using Eclipse Version 15.1 TPS.In order to evaluate plan quality,dose coverage of target and dose to organs at risk,monitor unit efficiency,segment size and delivery time were compared.Results Halcyon treatment platform could meet the clinical objective.Dose distribution of the target volume had no significant difference with the Trilogy plans (P＞0.05).Volumes receiving 10 Gy,20 Gy and D of the left lung were significantly reduced(Z=-2.22--1.78,P＜0.05).V5 of heart for Halcyon and Trilogy was(27.80±7.66)％ and (23.18±8.19)％,respectively(Z=-0.71,P＜0.05),while D was (7.03± 1.8)Gy and(7.11±2.40)Gy,respectively(P＞0.05).Halcyon increased the monitor unit from 1 526.2±227.7 by Trilogy to 1 770.5±383.9(Z=-0.71,P＜0.05),but decreased the delivery time from (12.38± 1.49) min by Trilogy to (3.01 ±0.28) min (Z =-3.42,P＜ 0.05).Conclusion Halcyon treatment platform can meet the clinical requirements,reduce dose to normal tissue with high delivery efficiency.

Objective To study the dose volume histogram ( DVH ) difference of target and organs at risk in intensity-modulated radiation therapy ( IMRT ) planning of cervical cancer based on the interquartile range. Methods A total of 22 cervical cancer patients′ IMRT plans were retrospectively analyzed. Five groups of DVH curves of PTV and OARs ( bladder, rectum, left and right femoral heads) were derived from the Pinnacle3 planning system. The mean DVH curves and interquartile range of volume ( IQRvol ) as a function of dose were calculated from each group′s DVH curve. Results The maximum volume variation for PTV reached at IQRvol(54. 03 Gy) =6. 95%, the volume of the target reached by the prescription dose was ( 96. 43 ± 1. 63 )%. The maximum volume variation for bladder reached at IQRvol (17. 24 Gy) = 14. 62%. V40 and V30 for bladder were ( 32. 79 ± 7. 06 )% and ( 56. 47 ± 9. 94 )%, respectively. Rectal DVH showed the largest difference at 35. 92 Gy, with the quartile of 19. 94%, the V40 and V30 for rectum were (30. 17 ± 10. 80)% and (58. 16 ± 11. 99)%, respectively. The difference in the bladder and the rectum was statistically significant (z = -6. 59, P < 0. 05). The maximum volume variation of left femoral head reached at IQRvol(16. 06 Gy) =31. 47%. The maximum volume variation of right femoral head was reached at IQRvol (17. 47 Gy) =32. 82%. There was no significant difference in IQRvol between right and left femoral head (P>0. 05). Conclusions Quartile range curve of DVHs can be used to analyze the deviations of DVH curves of PTV and OARs, and provide guidance for automatic planning optimization parameter setting.

Objective To evaluate the position deviation of multi-leaf collimator (MLC) in volumetric modulated arc therapy for nasopharyngeal carcinoma and to verify a method of detecting the leaf position accuracy.Methods Thirty-two volumetric modulated arc plans of nasopharyngeal carcinoma were randomly selected.A clockwise arc with a gantry range of 181° to 179° and a counterclockwise arc with a gantry range of 179° to 181° were uscd for each plan.Each arc contained two leaf groups,groups A and B.By using the Argus software,the actual MLC leaf positions were extracted from the Dynalog files in the Varian Trilogy accelerator.The planed MLC leaf positions were compared with the actual positions,and the differences were calculated between them.Results The proportions of the leaf position errors within ± 2,± 1.5,± 1 and ± 0.5 mm were 99.99％,99.90％,99.07％ and 93.98％,respectively.The proportions of the leaf position errors within ± 1 mm were 98.08％,100％,98.97％ and 99.01％ for the first therapeutic arc (ARC1),second therapeutic arc (ARC2),A and B groups,respectively.The leaf position errors range of ARC1 and ARC2 were-2.95 to 2.99 and-0.22 to 0.23 mm (t =2.35,P ＜ 0.01).The leaf position errors range of leaf bank A and leaf bank B were-2.95 to 2.68 and-2.92 to 2.99 mm(P ＞ 0.05).Conclusions During the volumetric modulated arc radiotherapy,the leaf positions deviation are in control.The Dynalog files can be used as an effective way to analysis the leafposition errors.