Analysis of radioactive occupational hazard and protective measures in iodine-125 seed source manufacturer / 中国职业医学

Objective To analyze the occupational hazards and protective measures for personnel in an iodine-125(125I) seed source production company. Methods In 2022, a 125I seed source production enterprise in Guangdong Province was selected as the research subject. The occupational hazards in the workplace of the research subject was identified using the system engineering analysis method. The FLUAK program based on Monte Carlo method was used to simulate the blocking protection of the production of the 125I seed source, and to estimate the dose of internal and external irradiation of seed source that affected workers. Results The main occupational radiation hazards in the seed production were non-sealed radioactive materials, including external irradiation from X-ray and γ ray and internal irradiation from aerosols formed by iodine volatilization. Estimated maximum dose equivalent rate around the chest and eye lens for workers were 0.52 and 0.02 μSv/h, respectively. The expected annual effective dose for workers in each work site was 0.035 mSv, and the expected annual equivalent dose to the eye lens for all workers in various work sites was 0.001 mSv. The maximum annual equivalent dose of operator's hand was 80.620 mSv. The maximum dose of internal irradiation to the worker was 18.750 mSv, which was caused by the volatilization of nuclides. Conclusion With effective protection measures for internal and external irradiation in place, the annual exposure doses for seed production personnel and operator’s hand are below the national limits. Adequate measures should be taken on hand protection.

Radiation safety analysis of retrieval and conditioning of naturally occurring radioactive material waste / 中国辐射卫生

Objective The radioactivity level in historical waste from a plant is high, and decommissioning operators may be exposed to high radiation doses. The objective of the study is to carry out a radiation safety analysis of the retrieval and conditioning of naturally occurring radioactive material (NORM) waste, put forward appropriate radiation protection measures, and minimize the exposure doses of operators. Methods The source terms of NORM waste in the temporary storehouse were analyzed; MicroShield, a point kernel integration program, was used for modeling and calculation; and radiation protection measures under decommissioning conditions were put forward based on on-site monitoring data. Results The maximum gamma dose rate calculated near the waste pile in the temporary storehouse was 313.9 μGy/h, equivalent to the monitoring level; distance decay and appropriate shielding measures significantly reduced gamma dose rates for operators. Conclusion Decommissioning sites of temporary storehouses are of great harm to operators. Measures such as shielding, isolation, remote operations, and personal protection can effectively reduce the exposure doses of operators.

Intraoperative radiotherapy for soft tissue sarcoma / 医学研究生学报

Soft tissue sarcoma ( STS) , which is mostly found in extremities and retroperitoneum, is a malignant tumor of the connective tissue with the low incidence ( 1% of all malignant tumors) and various kinds of histopathological types. Intraoperative radio-therapy ( IORT) can improve the therapeutic effects of STS and to reserve the functions of the related organs, holding the apparent ad-vantage in local control rate of the tumor. IORT may cause toxicity, such as wound infections, limb ischemic necrosis and fibrosis. However, with the gradual development of IORT equipment, incidence rate of toxicity may be further reduced. This paper reviews the history, indications and advantages, clinical efficacy and adverse effect of IORT in STS.

A Clinical Trial in Improving External Irradiation Technique for Head-neck Neoplasms / 中国医师杂志

Objective To improve the external irradiation technique for Head-neck neoplasms.Methods 95 patients with Head-neck neoplasms confirmed by pathology,were fixed with head pillow mask , isocenter irradiation,technique utilizing cerrobend block.Radical therapy dose was 72 (70～80)Gy/35～40 fractions in 7～8 weeks for general carcinoma and 50～55Gy/28～31 fractions in 5 6～6 2 weeks for NHL .Preventive dose was 56 (50～60)Gy/25～30 fractions in 5～6 weeks for general carcinoma and 45～50Gy/25～28 fractions in 5～5 6 weeks for NHL.A short and a long-term clinical outcome, acute and late radiation reactions were observed.Results After 1～2 months following radiation therapy,CT scans revealed that the primary lesion complete remission rate was 58 57% , and obvious remission rate was 32 86%.The normal mucous membrane acute radiation reaction rates were G0 56 84% , GⅠ 42 10% , GⅡ 1 05%,respectively.After 1～2 years following radiation therapy,the spinal cord and brain stem radiation injury rate was zoro.Conclusions The improving external irradiation technique may elevate local control rate better,and reduce radiation reactions of patients with head-neck neoplasms.

The Role of Postoperative External Irradiation for the Incompletely Resected Meningiomas / 대한방사선종양학회지

PURPOSE: The aim of this study is to look for the possible efficacy of postoperative external irradiation for incompletely resected meningiomas. METHODS AND MATERIALS: From August 1981 to January 1997, forty-four patients with intracranial meningioma were treated by postoperative external irradiation. Of the 44 meningiomas, 18 transitional, 13 meningotheliomatous, 6 hemangiopericytic, 4 atypical, 2 fibroblastic and 1 malignant meningioma were identified. We classified all patients into two groups by the histology. The benign group was consisted of the meningotheliomatous, transitional and fibroblastic types. The malignant group was consisted of the atypical, hemangiopericytic and malignat types. In the means of surgery, 37 patients were resected incompletely and 7 patients were managed by biopsy only. After surgery, all patients were received postoperative external irradiation. Radiotherapy was deliverd using Co-60 or 4 MV photon beam to a total dose of 50 to 66 Gy (mean dose : 57.4 Gy) with a 1.8 to 2 Gy per fraction. The median follow-up was 48 months (range : 21~101 months). Multivariate analysis of the influence by age, sex, location, histology and radiation dose on local control has been done using Cox's proportional hazard model. RESULTS: 5-year local control rate was 93.8% for the benign histology and 51.8% for the malignant histology (p=0.0110) and overall local control rate at 5 years was 87.4%. The analysis of the prognostic factors, such as age, sex, location, and radiation dose were not significant except for the histology. CONCLUSION: Adjuvant postoperative external irradiation appears to be significantly improved local control in the patients with incompletely resected meningiomas.

The Role of External Irradiation for the Locally Advanced Papillary Thyroid Cancers / 대한방사선종양학회지

PURPOSE: The aim of this study is to look for the possible efficacy of external irradiation for locally advanced papillary thyroid cancers (stage pT4 or N1). METHODS AND MATERIALS: From August 1981 through September 1997, 91 Patients with locally advanced papillary thyroid cancers (stage pT4 or N1) have been treated with external irradiation and followed up at our clinic. All of the patients have been treated with surgical resection. After surgery, 23 patients received postoperative external irradiation with or without ablative radioiodine therapy, whereas the other 68 patients were treated with ablative radioiodine therapy alone. Distributions of sex, age, and stage were comparable in both irradiated and nonirradiated groups. Multivariate analysis of the influence by age, sex, stage, ablative radioiodine therapy and external irradiation on local control were performed by using Cox's proportional hazard model. RESULTS: Overall survival rates at 7 years were of no significant difference in both groups. There were 98.1% for no RT group and 90% for RT group (p=0.506).5-year local control rates were significantly different, these were 95.2% for RT group and 67.5% for no RT group (p=0.0408). An analysis of the prognostic factors, age, sex, stage, and RAI were not significant variables, except for the external irradiation. CONCLUSION: Adjuvant postoperative external irradiation did not affect overall survival, but significantly improved local control in the patients with locally advanced papillary thyroid cancers (stage pT4 or lymph node involvement).

Complication of Intraoperative Radiation Therapy (IORT) in Gastric Cancer / 대한치료방사선과학회지

Local control is the important prognostic factor in cancer treatment because local control decrease the relative risk of metastatic spread and increse distant metastasis free survival. IORT is the modality which could increase local control without incressing complication, combined with curative operation. Eventhough we could achieve significant deacreased local failure by IORT and curative resection, it should not be committed as a main treatment modality without proving acceptable complications. Therapeutic Radiology Department of Yeungnam University Medical Center have tried 58 IORT from June 15, 1988, and performed 53 IORT in patients with gastric cancer. No local failure has been reporte? by regular follow up so far. Nine cases(17%) of treatment related complifaiton were reported including intestinal obstrution, hemorrhage, sepsis, and bone marrow depression. These complications could be comparable to Jo's 25.2% (chemotherapy + operation), Kim's 18% (chemotherapy only in inoperable patients), because our treatment regimen is consisted of IORT (1500 cGy), external irradiation(--4500 cGy) and extensive chemotherapy (FAM, 5FU+MMC, BACOP). Our data encouraged us to re-inforce further IORT in stomach cancer treatment.

Early and Late Bowel Complication Following Irradiation of Cancer of the Uterine Cervix-Whole Pelvis Exlernal : Irradiation end High-Dose-Rate Inlracavitary Irradiation / 대한치료방사선과학회지

Cervix cancer is the most common female cancer in Korea. In spite of their relatively local invasive tendency, still 44% of patient will develop recurrent cancer This result suggests that more aggressive local treatment may increase the cure rate but increased complication risk also cannot be avoidable. Various institutions proposed different treatment regimen, but recommended dose were about 4500 cGy for whole pelvis and 8000 cGy at point A, even though they agreed that those doses may not be satisfactory for control of bulky disease. 96 cases of invasive cervical cancer, treated with postoperative or primary radiation therapy were analyzed to determine the complication rate and prognostic factor in our treatment regimen which is 500~1000 cGy higher than other institution. Mean follow up duration was 21 months. Symptomatic patients including mild but persistent abdominal discomfort was 46%, but only 1 patient (1%) had operative treatment because of incomplete obstruction of small bowel. Most symptoms appeared within 12 months and most common complaints were frequent bowel movement. Barium enema and sigmoidoscopy were performed for persistent symptomatic patients. Only one patient had abnormal finding in barium enema which showed inefficiency of this method for detecting bowel complication. Patient's age, total tumor dose, total TDF, rectal dose were not significant risk factors for complication, but boost dose, previous history of operation had some relationship with complication risk. Even though dose of point A and rectum is 500~1,000 cGy higher than other institution, such a low rate of severe complications may suggest that fear of complications should not be overestimated than cure rate and the possibility of more aggressive treatment for better local control should not be underestimated.