Objective:To investigate setup errors of two fixation methods of transparent head pillow and vacuum bag head pillow in patients with head and neck tumors when undergoing radiotherapy.Methods:A total of 40 patients with head and neck tumors undergoing radiotherapy admitted to Meizhou People's Hospital of Guangdong Province from January 2017 to December 2018 were selected and randomly divided into the control group (transparent head pillow fixation) and the research group (vacuum bag head pillow fixation), with 20 cases in each group. Kilovoltage cone-beam computed tomography (CBCT) was used to obtain the registration image data of each patient for 10 times during the linear accelerator treatment. The linear and rotational positioning errors of two groups were also analyzed.Results:The linear setup errors in the direction of left-right (X-axis), head-foot (Y-axis) and front-back (Z-axis) were (1.1±0.8) mm, (0.9±0.8) mm and (1.2±0.9) mm in the study group, and (1.3±1.1) mm, (1.1±1.1) mm and (1.4±1.1) mm in the control group. The rotation setup error of X-axis, Y-axis, Z-axis was (0.73±0.52) °, (1.08±0.89) ° and (0.89±0.74) °, respectively in the study group, and (0.81±0.69) °, (1.38±1.05) °, (0.88±0.70) °, respectively in the control group. The difference of linear setup error in Y-axis and Z-axis was statistically significant ( P = 0.016, P = 0.004). The difference of rotation setup error in X-axis and Y-axis was statistically significant ( P = 0.036, P = 0.001). Conclusion:The vacuum pillow is better than the transparent pillow in improving the rotation error and linear error for patients with head and neck tumors undergoing radiotherapy.

Objective:To investigate the value of flattening filter-free (FFF) mode in postoperative deep inspiration breath-hold (DIBH) intensigy-modulated radiotherapy for left breast cancer.Methods:A retrospective case series study was conducted. Clinical data of 21 patients with left breast cancer who underwent DIBH intensity-modulated radiotherapy after modified radical surgery in Meizhou People's Hospital from January 2021 to December 2022 were retrospectively analyzed. On the DIBH-mode CT of each patient, the 7-field intensity-modulation plan was designed using the plan developed in the 6 MV FFF-mode (FFF group) or the plan developed in the 6 MV flattening filter (FF)-mode (FF group). The target areas and organs at risk, dosimetric and biological parameters, and dose validation results were compared between the two plans.Results:Twenty-one patients were female with the age [ M ( Q1, Q3)] of 47 years old (32 years old, 61 years old). The percentage of target areas receiving 95% of the prescribed dose (V 95%) was (95.9±0.8)% and (95.7±1.9)% in the FF and FFF groups ( t = 2.98, P = 0.089), and the maximum dose was (5 401±251) cGy and (5 424±201) cGy ( t = 2.85, P = 0.181), the fitness indices were 0.88±0.05 and 0.87±0.06 ( t = 0.32, P = 0.562), the homogeneity indices were 1.06±0.01 and 1.07±0.02 ( t = 2.91, P = 0.009), the equivalent uniform doses (EUD) were (51.81±0.21) Gy and (51.97±0.20) Gy ( t = 0.51, P = 0.309), and the tumor control probability (TCP) was (99.68±0.01)% and (99.61±0.02)% ( t = 0.81, P = 0.560). The plans of the FFF group and the FF group were compliant, and the doses of all organs at risk to be irradiated were within the clinically acceptable range, and the radiation doses in the FFF group in the left lung [5 Gy irradiated volume (V 5 Gy), mean dose (D mean), EUD and normal tissue complication rate (NTCP)], right lung (V 5 Gy and D mean), heart (V 10 Gy, D mean, EUD and NTCP), and right breast (V 5 Gy, D mean and EUD) were differently lower than those in the FF group, and the differences were statistically significant (all P < 0.05). The monitor units in the FFF and FF groups were (984±132) MU and (751±145) MU ( t = -1.25, P < 0.001), and the total beam-on time was (1.4±0.3) min and (2.2±0.4) min ( t = 0.68, P < 0.001); individual field beam-on time was (12±7) s and (16±10) s ( t = 2.68, P = 0.001), and the beam-on time for each field in patients of the FFF group was less than 25 s; γ pass rates were (97.1±2.8)% and (97.6±2.1)% ( t = 0.59, P = 0.484). Conclusions:In the intensity-modulated radiotherapy of left breast cancer, the radiation dose of the energy to the critical organs in FFF mode is lower and has higher dose rate and shorter treatment time. FFF combined with DIBH technique has positive clinical significance in the intensity-modulated radiotherapy of breast cancer.

Objective:To investigate the clinical effect of "ladder reduction method" in the treatment of iliac fracture combined anterior dislocation of sacroiliac joint.Methods:The retrospective analysis was performed on 10 cases of iliac fracture combined anterior sacroiliac joint dislocation admitted to the Affiliated Hospital of Yunnan University from February 2010 to January 2022, among which 5 cases were males and 5 cases were females, aged ranging from 22 to 52 years, with an average age of 38.8 years. All patients were injured in car accidents including 5 cases of C1.2, 3 cases of C2, and 2 cases of C3 fractures according to Tile classification. All patients were treated with the "ladder reduction method" with plate and screw fixation. In the first step, 1-2 Schanz pins were inserted into the iliac crest to control the ilium, and the Schanz pins were appropriately pulled laterally; in the second step, the periosteal stripper was used to pry the reduction between the sacrum and ilium; in the third step, for the patients who still could not be reduced, a 2.5 mm diameter Kirschner wire was placed on the sacrum close to the iliac crest, and a periosteal stripper was inserted between the sacrum and iliac crest, with its tip against the Kirkner wire, and the iliac crest as the fulcrum for pry pulling to separate the two. In the fourth step, the pry was maintained, and then another 2.5 mm diameter Kirschner wire was placed on the sacrum close to the internal margin of the iliac bone. The periosteal stripper was continued to pry between the sacrum and the iliac bone, and the operation was repeated. At the same time, the anterior dislocation of the sacroiliac joint was reduced with traction of the lower limb. Postoperatively, the quality of reduction was evaluated by the Matta score, and the degree of functional recovery after pelvic fracture was evaluated by the Majeed score.Results:Four patients completed the reduction through the first and second steps, and 6 cases of refractory sacroiliac joint anterior dislocation were successfully reduced through the first to fourth steps. The fracture reduction time of 6 patients with refractory anterior sacroiliac joint dislocation was 39.67±3.09 min (range, 35-44 min), with intraoperative blood loss of 300.00±141.42 ml (range, 150-600 ml); in the other 4 cases, the fracture reduction time was 36.75±4.38 min (range, 30-42 min), and the intraoperative blood loss was 225.00±44.30 ml (range, 200-300 ml). All 10 patients were followed up for 12.9±3.7 months (range, 9-20 months). The anterior and posterior pelvic ring fractures were healed in all patients, and the fracture healing time was 12.77±1.62 weeks (range, 10.71-15.28 weeks). At the last follow-up, Matta evaluation was excellent in 5 cases, good in 1 case, and excellent in the other 4 cases. The Majeed scores of 6 cases were 86.50±6.08 points (range, 74-92 points), of which 5 cases were excellent and 1 case was good. The other 4 cases were 81.5±9.39 scores (range, 71-94), of which 2 were excellent and 2 were good.Conclusion:The "ladder reduction method" is a safe, effective and easy-to-operate method for the treatment of iliac fracture combined anterior dislocation of the sacroiliac joint, especially for refractory anterior dislocation of the sacroiliac joint, which can still obtain satisfactory curative effects.