Objective:To investigate the dosimetric differences between non-coplanar volumetric modulated arc therapy (VMAT) and non-coplanar fixed-field intensity-modulated radiotherapy (IMRT) of Monaco treatment planning system (TPS) in hippocampus-avoidance whole-brain radiation therapy with simultaneous integrated boost(HA-WBRT+SIB) for brain metastases,so as to provide a practical and feasible treatment plan for clinical work. Methods:A total of 22 patients with brain metastases were retrospectively selected. Two radiotherapy plans,which included non-coplanar VMAT and non-coplanar fixed field IMRT of HA-WBRT+SIB,were designed for each patient. The dose distribution,the machine units (MU) of plan,and verification of pre-treatment plan in target area and organs at risk (OARs) between two plans were compared under meeting the prescribed dose requirements of target volume. Results:There were no significant differences in covered volumes (V50 and V55) of 50 and 55 Gy dose,maximum dose (Dmax),heterogeneity index(HI) and conformity index(CI) of planning gross tumor volume(PGTV) between the two plans (P>0.05). For whole-brain planning target volume (PTV-brain-SIB),there was no significant difference in the dose that was covered by 98％ volume (D98％) between IMRT and VMAT (P<0.05). VMAT plan could significantly improve the covered volume of 30 Gy dose (V30) of PTV-brain-SIB,and decrease HI value and increase CI value,and the differences of them between VMAT and IMRT were significant (t=-6.366,3.289,-8.343,P<0.05),respectively. The Dmax values of left and right eyes of VMAT plan were significantly lower than those of IMRT plan,and the differences were significant (t=5.784,5.351,P<0.05),respectively. The Dmax value of right inner ear of VMAT plan was higher than that of IMRT plan,and the difference was significant (t=-2.848,P<0.05). VMAT could significantly increase D100％ value of left and right hippocampus,which was higher than that of IMRT plan,and the differences of them between two plans were significant (t=-2.564,-6.578,P<0.05),respectively. The MU of IMRT plan was significantly lower than that of VMAT plan,and the difference was significant (t=-6.249,P<0.05). The treatment time of VMAT plan was (294.1±16.4) s,which was significantly less than that of IMRT plan,and the difference of that between two plans was significant (t=-7.400,P<0.001). Under the standards of 3％/2 mm and 2％/2 mm of γ analysis,the γ pass rates of IMRT plan were respectively (99.1±0.6)％ and (97.6％±1.0)％,which were significantly higher than those of VMAT plan,and the differences of them were significant (t=-2.733,t=-5.780,P<0.001),respectively. Conclusion:The non-coplanar VMAT and non-coplanar fixed field IMRT based on the Monaco TPS can produce clinically acceptable results for HA-WBRT+SIB in patients with brain metastases. Compared with IMRT,VMAT has better advantage in dose distribution of target volume,and higher treatment efficiency,but IMRT can better protect the hippocampus and reduce the number of MU.

Objective:To investigate the dosimetric differences between non-coplanar volumetric modulated arc therapy (VMAT) and non-coplanar fixed-field intensity-modulated radiotherapy (IMRT) of Monaco treatment planning system (TPS) in hippocampus-avoidance whole-brain radiation therapy with simultaneous integrated boost(HA-WBRT+SIB) for brain metastases,so as to provide a practical and feasible treatment plan for clinical work. Methods:A total of 22 patients with brain metastases were retrospectively selected. Two radiotherapy plans,which included non-coplanar VMAT and non-coplanar fixed field IMRT of HA-WBRT+SIB,were designed for each patient. The dose distribution,the machine units (MU) of plan,and verification of pre-treatment plan in target area and organs at risk (OARs) between two plans were compared under meeting the prescribed dose requirements of target volume. Results:There were no significant differences in covered volumes (V50 and V55) of 50 and 55 Gy dose,maximum dose (Dmax),heterogeneity index(HI) and conformity index(CI) of planning gross tumor volume(PGTV) between the two plans (P>0.05). For whole-brain planning target volume (PTV-brain-SIB),there was no significant difference in the dose that was covered by 98％ volume (D98％) between IMRT and VMAT (P<0.05). VMAT plan could significantly improve the covered volume of 30 Gy dose (V30) of PTV-brain-SIB,and decrease HI value and increase CI value,and the differences of them between VMAT and IMRT were significant (t=-6.366,3.289,-8.343,P<0.05),respectively. The Dmax values of left and right eyes of VMAT plan were significantly lower than those of IMRT plan,and the differences were significant (t=5.784,5.351,P<0.05),respectively. The Dmax value of right inner ear of VMAT plan was higher than that of IMRT plan,and the difference was significant (t=-2.848,P<0.05). VMAT could significantly increase D100％ value of left and right hippocampus,which was higher than that of IMRT plan,and the differences of them between two plans were significant (t=-2.564,-6.578,P<0.05),respectively. The MU of IMRT plan was significantly lower than that of VMAT plan,and the difference was significant (t=-6.249,P<0.05). The treatment time of VMAT plan was (294.1±16.4) s,which was significantly less than that of IMRT plan,and the difference of that between two plans was significant (t=-7.400,P<0.001). Under the standards of 3％/2 mm and 2％/2 mm of γ analysis,the γ pass rates of IMRT plan were respectively (99.1±0.6)％ and (97.6％±1.0)％,which were significantly higher than those of VMAT plan,and the differences of them were significant (t=-2.733,t=-5.780,P<0.001),respectively. Conclusion:The non-coplanar VMAT and non-coplanar fixed field IMRT based on the Monaco TPS can produce clinically acceptable results for HA-WBRT+SIB in patients with brain metastases. Compared with IMRT,VMAT has better advantage in dose distribution of target volume,and higher treatment efficiency,but IMRT can better protect the hippocampus and reduce the number of MU.

Objective:To compare the diagnostic efficacy of 18F-prostate specific membrane antigen (PSMA)-1007 PET/CT and mpMRI in the diagnosis of pelvic lymph node metastasis of prostate cancer (PCa). Methods:The clinical data of 30 patients who underwent 18F-PSMA-1007 PET/CT and mpMRI examinations in Sichuan Cancer Hospital from November 2018 to April 2021 were analyzed. The average age was (68.4±6.4) years old. The preoperative total PSA was 45.70(16.07, 100.00)ng/ml. Among 30 patients, 14 cases were found lymph node positive by PET/CT and 7 cases were found lymph node positive by mpMRI.Combined with the two preoperative imaging methods and the patient's PSA level, there was 1 patient in stage T 1, 20 patients in stage T 2, 6 patients in stage T 3, and 3 patients in stage T 4. Twenty-nine cases were classified as high risk group and one case was in moderate risk group.All 30 patients underwent laparoscopic radical prostatectomy and enlarged pelvic lymph node dissection (ePLND). According to the postoperative pathological results, the sensitivity, specificity, positive predictive value and negative predictive value of the two imaging techniques for the diagnosis of PCa pelvic lymph node metastasis were calculated, and the consistency of the two imaging techniques for the postoperative pathological results was observed by Kappa test. Results:All the 30 patients were confirmed to be PCa by postoperative pathology, among which 10 patients were positive for pelvic lymph node biopsy. The sensitivity, specificity, positive predictive value and negative predictive value of 18F-PSMA-1007 PET/CT for pelvic lymph node metastasis were 100.0% (10/10), 80.0% (16/20), 71.4%(10/14) and 100.0%(16/16) respectively, and Kappa value was 0.727. The sensitivity and specificity of mpMRI were 70.0% (7/10) and 100.0% (20/20), the positive and negative predictive values were 100.0% (7/7) and 87.0%(20/23)respectively, and the Kappa value was 0.757. The P values of sensitivity, specificity, positive predictive value and negative predictive value between the two imaging methods were 0.18, 0.07, 0.30, <0.01, respectively. The sensitivity, specificity, positive predictive value and negative predictive value of 18F-PSMA-1007 PET/CT in diagnosing the number of pelvic lymph node metastasis were 100%(28/28), 98.2% (373/380), 80.0% (28/35) and 100.0%(373/373), respectively. The sensitivity, specificity, positive predictive value and negative predictive value of mpMRI in diagnosing the number of pelvic lymph node metastasis were 78.6% (22/28), 100.0% (380/380), 100.0% (22/22) and 98.4%(380/386), respectively. The P values of the sensitivity, specificity, positive predictive value and negative predictive value of lymph node detection by the two imaging methods were all <0.01, and the differences were statistically significant. Conclusions:The sensitivity and negative predictive value of 18F-PSMA-1007 PET/CT for the detection of positive lymph node were higher than mpMRI. The specificity and positive predictive value of mpMRI in detecting positive lymph node metastasis were higher than 18F-PSMA-1007 PET/CT examination.

Objective To illustrate the basic operational principle of the control software item Part and value ( IPV) of Elekta digital medical linac and specifically explain that the control software monitors and controls the subsystems in a real-time manner by using three types of items and Parts. Methods Firstly, the composition of the control system of Elekta digital medical linac was introduced. Then, the definition and category of the items and Parts of the control software and the basic principle of different types of items were illustrated. Finally, the application of control software items and Parts in real-time monitoring and controlling the operation of subsystems was evaluated by analyzing the motion control of high-power ( HP) phase shifter. Results By analyzing the principle and citing a classical example to specifically illustrate the operational principle and application of control software IPVs, the users, especially the maintenance personnel, could master relevant theoretical knowledge, rapidly and accurately find the operational parameters during daily use and maintenance, besides analyze and resolve the problems based on the control principle of relevant subsystem. Conclusion Users, especially the maintenance personnel who master the working principle of these subprojects and their project sub-items can quickly and accurately check, calibrate the operating parameters via the control software, resolve equipment failure and avoid accidents caused by inappropriate operation in the daily use or maintenance.

Objective To investigate the correlation between three gene locus polymorphisms of X-ray repair cross-complementary protein 1 (XRCC1) exon (Arg194Trp, Arg280His and Arg399Gln) and the risk of colorectal cancer (CRC). Methods A case-control study was performed in 250 CRC patients (case group, 128 colon cancer patients and 122 rectal cancer patients) and 213 healthy individuals (control group). The three gene locus polymorphism of XRCC1 was tested by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. The genotype distribution and allele frequency of each locus was analyzed with SPSS 10.0 software. Results There was no significant difference in allele frequency of XRCC1 at 194 and 399 loci (P > 0.05). However, the 280 Arg/His allele frequency of XRCC1 was higher in case group than that in control group (OR=1.66,95%CI:1.01~2.73,P=0.047). The 280Arg/His allele frequency was higher in rectal cancer group than that in control group (OR =1.82,95%CI:1.02~3.27). The frequency of 280His allele (Arg280His and His280His) was higher in case group than that in control group (OR=1.85,95%CI:1.06~3.22). However, it was a relative low risk factor of colon cancer and there was no significant difference between colon cancer group and control group (OR=1.85, 95%CI:1.06~3.22). Conclusions There was no correlation between XRCC1 Arg194Trp and Arg399Gln polymorpohisms and the risk of CRC. However, 280Arg/His genotype may increase the risk of CRC, and 280His allele is a risk factor of rectal cancer.