Clinical exploratory study on reduction of clinical target volume in postoperative intensity-modulated radiotherapy for parotid gland cancer / 中华放射肿瘤学杂志

Objective:To evaluate the effect of reducing clinical target volume (CTV) on local control and overall survival in postoperative intensity-modulated radiotherapy (IMRT), and analyze the patterns of failure, aiming to provide clinical basis for postoperative IMRT delineation of CTV for parotid gland cancer in the era of precision radiotherapy.Methods:Clinical data of 126 patients who were pathologically diagnosed with parotid gland cancer and treated with parotidectomy as well as postoperative radiotherapy were retrospectively analyzed. All patients were divided into two groups according to the prozone of CTV. It was delineated to the anterior border of parotid gland in group A, and delineated to the anterior border of masseter in group B. Actuarial estimates of local recurrence-free survival, regional recurrence-free survival, distant metastasis-free survival and overall survival were obtained with the Kaplan-Meier method. Univariate prognostic analysis was performed by log-rank test. Multivariate prognostic analysis was conducted by Cox regression model.Results:The 5-year local recurrence-free survival (LRFS), regional recurrence-free survival (RRFS), distant metastasis-free survival (DMFS) and overall survival (OS) in groups A and B were 96.7% vs. 91.3%, 96.7% vs. 90.2%, 86.9% v s. 81.3% and 86.0% vs. 81.4%, respectively. There were no significant differences in these parameters between two groups. Of 126 patients with parotid carcinoma, 7 had local recurrence. There were 2 cases in group A which 1 recurred in-field and 1 recurred out- field. And there were 5 cases in group B which 4 recurred in-field and 1 recurred marginally. Univariate analysis showed that age was associated with LRFS. Age, N stage and pathological grading were associated with OS. Cox multivariate analysis revealed that age, N stage and pathological grading were the independent influencing factors of OS. Conclusions:Reducing the CTV would not increase the risk of local recurrence in patients with parotid gland carcinoma without tumor extravasation and negative surgical margins. There is no significant difference in survival benefit compared to those delineated to the anterior border of the masseter muscle. The delineation of CTV should be treated differently according to the risk factors.

The patterns of failure with three-dimensional radiation therapy for primary tumors of stage Ⅳ NSCLC / 中华放射肿瘤学杂志

Objective:To explore the characteristics of failure patterns of three-dimensional radiotherapy combined with first-line drug therapy for primary tumors of stage Ⅳ non-small cell lung cancer(NSCLC)and investigate the influence of radiotherapy-related factors.Methods:708 patients newly-diagnosed with stage Ⅳ NSCLC from March 2003 to July 2020 were selected. Chi-square test was used for univariate analysis of failure patterns. Kaplan-Meier method, Log-rank test and Cox regression model were employed for multivariate analysis. Results:The incidence of first-line treatment failure in 708 cases was 71.2%, and the incidence of treatment failure was 22.7%, 28.8%, 13.3%, and 6.4% for ≤6 months, >6-12 months, >12-24 months, and>24 months, respectively, and the median survival time was 7.2, 13.4, 22.2, and 37.6 months, which was significantly different( χ2=226.013, P<0.001). The incidence of recurrence failure(RF)was 21.3%.There was no significant difference in the incidence of RF between oligometastasis(OM)and non-oligometastasis(NOM). The incidence of DF was 66.3% and the order of incidence was brain>bone>lung>pleural cavity>liver>distant lymph nodes>adrenal gland>other sites, occurring in approximately 1/2 of AM and 1/3 of PSM cases. Metastatic status, time to treatment failure, pathological type, gender, combined treatment intensity were the independent influencing factors for predicting prognosis. Conclusions:The failure pattern of radiotherapy for primary tumors of stage Ⅳ NSCLC is different from that of first-line drug therapy, with significantly lower local failure and predominantly metastatic failure. The incidence of brain metastasis is the highest. The later time to treatment failure, the longer the overall survival(OS). OM, female, non-squamous cell carcinoma, late treatment failure, 4-6 cycles of chemotherapy over the same period ≥63 Gy are the independent prognostic factors for prolonging survival.

Statistical Analysis of Operating Efficiency and Failures of a Medical Linear Accelerator for Ten Years / 대한방사선종양학회지

PURPOSE: To improve the management of a medical linear accelerator, the records of operational failures of a Varian CL2100C over a ten year period were retrospectively analyzed. MATERIALS AND METHODS: The failures were classified according to the involved functional subunits, with each class rated into one of three levels depending on the operational conditions. The relationships between the failure rate and working ratio and between the failure rate and outside temperature were investigated. In addition, the average life time of the main part and the operating efficiency over the last 4 years were analyzed. RESULTS: Among the recorded failures (total 587 failures), the most frequent failure was observed in the parts related with the collimation system, including the monitor chamber, which accounted for 20% of all failures. With regard to the operational conditions, 2nd level of failures, which temporally interrupted treatments, were the most frequent. Third level of failures, which interrupted treatment for more than several hours, were mostly caused by the accelerating subunit. The number of failures was increased with number of treatments and operating time. The average life-times of the Klystron and Thyratron became shorter as the working ratio increased, and were 42 and 83% of the expected values, respectively. The operating efficiency was maintained at 95% or higher, but this value slightly decreased. There was no significant correlation between the number of failures and the outside temperature. CONCLUSION: The maintenance of detailed equipment problems and failures records over a long period of time can provide good knowledge of equipment function as well as the capability of predicting future failure. More rigorous equipment maintenance is required for old medical linear accelerators for the advanced avoidance of serious failure and to improve the quality of patient treatment.

Statistical Analysis of Operating Efficiency and Failures of a Medical Linear Accelerator for Ten Years / 대한방사선종양학회지

PURPOSE: To improve the management of a medical linear accelerator, the records of operational failures of a Varian CL2100C over a ten year period were retrospectively analyzed. MATERIALS AND METHODS: The failures were classified according to the involved functional subunits, with each class rated into one of three levels depending on the operational conditions. The relationships between the failure rate and working ratio and between the failure rate and outside temperature were investigated. In addition, the average life time of the main part and the operating efficiency over the last 4 years were analyzed. RESULTS: Among the recorded failures (total 587 failures), the most frequent failure was observed in the parts related with the collimation system, including the monitor chamber, which accounted for 20% of all failures. With regard to the operational conditions, 2nd level of failures, which temporally interrupted treatments, were the most frequent. Third level of failures, which interrupted treatment for more than several hours, were mostly caused by the accelerating subunit. The number of failures was increased with number of treatments and operating time. The average life-times of the Klystron and Thyratron became shorter as the working ratio increased, and were 42 and 83% of the expected values, respectively. The operating efficiency was maintained at 95% or higher, but this value slightly decreased. There was no significant correlation between the number of failures and the outside temperature. CONCLUSION: The maintenance of detailed equipment problems and failures records over a long period of time can provide good knowledge of equipment function as well as the capability of predicting future failure. More rigorous equipment maintenance is required for old medical linear accelerators for the advanced avoidance of serious failure and to improve the quality of patient treatment.

The Pattern of Failure after Definitive Radiotherapy for Squamous Cell Carcinoma of the Lung / 대한치료방사선과학회지

From Feb. 1985 to Feb. 1988, 76 patients with squamous cell carcinoma of the lung treated at the Department of Therapeutic Radiology in Kyungpook National University Hospital were available for the analysis of this study. All patients received radiation of 4000c0y-6600c0y with curative aim. The overall rate of complete response was 25.0% and partial response was 52.6%. The complete and partial regression of tumor was 14.3% in patients treated with dose below 5000 cGy and 84.1% in the group treated with dose above 5000 cGy (p<0.01). The complete response was seen only in the group of patients received radiation at least 6000 cGy. The patterns of failure were as follows. The rate of initial intrathoracic recurrence was 52.6% in patients with complete response. The overall rate of failure was 67.8%. Distant metastasis was found in 47.4% of patients. Bone, contralateral lung, and brain were common metastatic sites in decreasing order. All of the distant metastases and 80% of local recurrences were found within the first year after treatment.