Primary research on neoplasm needle track implantation metastasis after radioactive seeds implantation and preventive measures

Objective:To observe the possibility of neoplasm needle track implantation after radioactive seeds implantation and seek preventive measures to avoid it.Methods:Superficial tissue of 250 seeding needle cores and 250 stylophores employed in neoplasm radioactive seeds implantation was smeared on slides to search for tumor cells.All patients received chemotherapy or endocrine therapy after operations.Ultrasound B-mode or computer tomography(CT)was performed at 10th day,30th day,60th day,and 180th day post operation to detect neoplasm implantation metastasis through needle tracks. Results:Positive cells were found on 13 of 250(5.20%)cores,and 7 of 250(2.80%)stylophores.The difference was not sta- tistically significant(P>0.05).The positive cells frequency of needles those traversed distance less than 3 cm in normal tissue was 6.19%(13/210),while the frequency of the others those traversed longer distance in normal tissue was 2.41%(7/290). The positive cells frequency of needles traversing different distances in normal tissues is significantly different(P<0.05).No neoplasm was detected through needle tracks by ultrasound B-mode or CT in 180 days after operation.Conclusion:Tumor cells could ablate into the needle track during radioactive seed implantation.Some preventive measures,such as optimization of pre-operation and intra-operation treatment plan,chemotherapy or endocrine therapy after operation,may be beneficial to avoid the implantation metastasis of neoplasm in seeding needle tracks.

DTI and pathological changes in a rabbit model of radiation injury to the spinal cord after ^(125)I radioactive seed implantation

Excessive radiation exposure may lead to edema of the spinal cord and deterioration of the nervous system. Magnetic resonance imaging can be used to judge and assess the extent of edema and to evaluate pathological changes and thus may be used for the evaluation of spinal cord injuries caused by radiation therapy. Radioactive ^125I seeds to irradiate 90% of the spinal cord tissue at doses of 40–100 Gy （D90） were implanted in rabbits at T10 to induce radiation injury, and we evaluated their safety for use in the spinal cord. Diffusion tensor imaging showed that with increased D90, the apparent diffusion coefficient and fractional anisotropy values were increased. Moreover, pathological damage of neurons and microvessels in the gray matter and white matter was aggravated. At 2 months after implantation, obvious pathological injury was visible in the spinal cords of each group. Magnetic resonance diffusion tensor imaging revealed the radiation injury to the spinal cord, and we quantified the degree of spinal cord injury through apparent diffusion coefficient and fractional anisotropy.

Significance of 125I radioactive seed implantation on growth differentiation factor and programmed death receptor-1 during treatment of oral cancer

BACKGROUND Oral cancer(OC)is the most common malignant tumor in the oral cavity,and is mainly seen in middle-aged and elderly men.At present,OC is mainly treated clinically by surgery or combined with radiotherapy and chemotherapy;but recently,more and more studies have shown that the stress trauma caused by surgery and the side effects of radiotherapy and chemotherapy seriously affect the prognosis of patients.AIM To determine the significance of 125I radioactive seed implantation on growth differentiation factor 11(GDF11)and programmed death receptor-1(PD-1)during treatment of OC.METHODS A total of 184 OC patients admitted to The Second Affiliated Hospital of Jiamusi University from May 2015 to May 2017 were selected as the research subjects for prospective analysis.Of these patients,89 who received 125I radioactive seed implantation therapy were regarded as the research group(RG)and 95 patients who received surgical treatment were regarded as the control group(CG).The clinical efficacy,incidence of adverse reactions and changes in GDF11 and PD-1 before treatment(T0),2 wk after treatment(T1),4 wk after treatment(T2)and 6 wk after treatment(T3)were compared between the two groups.RESULTS The efficacy and recurrence rate in the RG were better than those in the CG(P<0.05),while the incidence of adverse reactions and survival rate were not different.There was no difference in GDF11 and PD-1 between the two groups at T0 and T1,but these factors were lower in the RG than in the CG at T2 and T3(P<0.05).Using receiver operating characteristic(ROC)curve analysis,GDF11 and PD-1 had good predictive value for efficacy and recurrence(P<0.001).CONCLUSION 125I radioactive seed implantation has clinical efficacy and can reduce the recurrence rate in patients with OC.This therapy has marked potential in clinical application.The detection of GDF11 and PD-1 in patients during treatment showed good predictive value for treatment efficacy and recurrence in OC patients,and may be potential targets for future OC treatment.

Dosimetry for ^(125) I radioactive seed implantation therapy for hepatocellular carcinoma

Hepatocellular carcinoma （HCC） is an aggressive malignancy. Early lesions respond well to hepatic resection or liver transplantation. However, only a few of HCC patients are suitable for surgical intervention. External beam radiation and chemotherapy is poorly efficacious. In the last 20 years, HCCs belonging to the radiosensitive tumor group has been confirmed. Along with the development of new radiotherapy technology and facilities, the research about brachytherapy（especially ^125I seed implantation therapy） has provoked more interests in the world. Radioactive seed implantation therapy is a form of interstitial brachytherapy, with the property of local ＂conformal radiotherapy＂ and the advantages of minimal invasion, convenience, high performance, and minimal adverse effects. It is a promising therapy for HCC, however the dosimetry hasn＇ t yet been identified and lacks verification in prospective research. This report aims to further explore the best prescription dose and radioactivity for ^125I interstitial implantation brachytherapy for HCC.

Implanting iodine-125 seeds into rat dorsal root ganglion for neuropathic pain: neuronal microdamage without impacting hind limb motion

The use of iodine-125 （L251） in cancer treatment has been shown to relieve patients＇ pain. Consid- ering dorsal root ganglia are critical for neural transmission between the peripheral and central nervous systems, we assumed that 125I could be implanted into rat dorsal root ganglia to provide relief for neuropathic pain. 125I seeds with different radioactivity （0, 14.8, 29.6 MBq） were im- planted separately through L4-5 and L5-6 intervertebral foramen into the vicinity of the L5 dorsal root ganglion, von Frey hair results demonstrated the mechanical pain threshold was elevated after implanting 125I seeds from the high radioactivity group. Transmission electron microscopy revealed that nuclear membrane shrinkage, nucleolar margination, widespread mitochondrial swelling, partial vacuolization, lysosome increase, and partial endoplasmic reticulum dilation were visible at 1,440 hours in the low radioactivity group and at 336 hours in the high radio- activity group. Abundant nuclear membrane shrinkage, partial fuzzy nuclear membrane and endoplasmic reticulum necrosis were observed at 1,440 hours in the high radioactivity group. No significant difference in combined behavioral scores was detected between preoperation and postoperation in the low and high radioactivity groups. These results suggested that the mechan- ical pain threshold was elevated after implanting 125I seeds without influencing motor functions of the hind limb, although cell injury was present.

To explore the curative effect of CT-guided Iodine-125 radioactive seed implantation in the treatment of stage Ⅳprimary hepatocellular carcinoma

Objectives: To explore the clinical efficacy and survival of CT-guided Iodine-125 radioactive seed implantation in the treatment of stage Ⅳ primary hepatocellular carcinoma.Methods: A retrospective study of 62 patients with primary hepatocellular carcinoma in our hospital from January2017 to December 2018 [60 males, 2 females, age(52.76 ± 10.82) years old], All patients were implanted with Iodine-125 radioactive seeds under CT guidance, followed up regularly after operation to observe the clinical efficacy, including comparison of changes in cancer size before and after treatment, tumor marker AFP, and improvement in complications such as abdominal pain and ascites. Follow-up 3–36 months to assess patient survival.Results: Among the 62 patients, 3 months after Iodine-125 radioactive seed implantation, 5 cases(8.1%) had complete remission of cancer, 33 cases(53.2%) had partial remission, 12 cases(19.4%) had stable lesions, and 12 cases(19.4%) had disease progression. The effective rate was 61.3%. The tumor volume(31.44 ± 14.51 cm3) was significantly smaller than before(50.96 ± 30.13 cm3)(t=5.303, p < 0.05). The tumor marker AFP(69.28 ±50.99) ug/L of 3 months after implantation was significantly lower than that before treatment(90.63 ± 68.58)ug/L(t=3.702, P < 0.05). The average survival time of Iodine-125 seed implantation for stageⅣhepatocellular carcinoma is 11.47 ± 0.85 months, and the median survival time is 9 months. The survival time of the group with better pathological differentiation(grade Ⅰ+ⅡⅠ) was significantly better than that of the group with poor differentiation(grade Ⅲ+Ⅳ)(x2=6.869 p < 0.05). Among the 38 patients with different degrees of abdominal pain,22 patients improved better than before;15 of 28 patients with different degrees of ascites were better than before. All patients had no serious complications related to treatment.Conclusions: Iodine-125 radioactive seed implantation therapy can safely and effectively treat hepatocellular carcinoma, and relieve the clinical symptoms of abdominal pain and ascites.

Radioactive 125I seed implantation for pancreatic cancer with unexpected liver metastasis:A preliminary experience with 26 patients

BACKGROUND Preoperative diagnosis rate of pancreatic cancer has increased year by year.The prognosis of pancreatic cancer patients with unexpected liver metastasis found by intraoperative exploration is very poor,and there is no effective and unified treatment strategy.AIM To evaluate the therapeutic effect of radioactive 125I seed implantation for pancreatic cancer patients with unexpected liver metastasis.METHODS The demographics and perioperative outcomes of patients who underwent 125I seed implantation to treat pancreatic cancer with unexpected liver metastasis between January 1,2017 and June 1,2019 were retrospectively analyzed.During the operation,125I seeds were implanted into the pancreatic tumor under the guidance of intraoperative ultrasound,with a spacing of 1.5 cm and a row spacing of 1.5 cm.For patients with obstructive jaundice and digestive tract obstruction,choledochojejunostomy and gastroenterostomy were performed simultaneously.After operation,the patients were divided into a non-chemotherapy group and a chemotherapy group that received gemcitabine combined with albumin-bound paclitaxel treatment.RESULTS Preoperative imaging evaluation of all patients in this study showed that the tumor was resectable without liver metastasis.There were 26 patients in this study,including 18 males and 8 females,aged 60.5±9.7 years.The most common tumor site was the pancreatic head(17,65.4%),followed by the pancreatic neck and body(6,23.2%)and pancreatic tail(3,11.4%).Fourteen patients(53.8%)underwent palliative surgery and postoperative pain relief occurred in 22 patients(84.6%).The estimated blood loss in operation was 148.3±282.1 mL and one patient received blood transfusion.The postoperative hospital stay was 7.6±2.8 d.One patient had biliary fistula,one had pancreatic fistula,and all recovered after conservative treatment.After operation,7 patients received chemotherapy and 19 did not.The 1-year survival rate was significantly higher in patients who received chemotherapy than in those who did not(68.6%vs 15.8%,P=0.012).The mean overall survival of patients in the chemotherapy group and non-chemotherapy group was 16.3 mo and 10 mo,respectively(χ2=7.083,P=0.008).CONCLUSION Radioactive 125I seed implantation combined with postoperative chemotherapy can prolong the survival time and relieve pain of pancreatic cancer patients with unexpected liver metastasis.

A prospective study:intraoperative ^(125)I radioactive seed implant therapy in advanced esophageal squamous cell carcinoma

Objective： To investigated the role of intraoperative iodine-125 （125I） brachytherapy as a treatment option for advanced thoracic esophageal squamous cell carcinoma （ESCC）. Methods： Using preoperative computed tomography （CT）-based staging criteria, between 2000 and 2008, 298 patients with ESCC （stage Ⅱ-Ⅲ） were enrolled in this prospective study. With informed consent, patients were randomized into two groups： intraoperative ^125^I seed implantation and surgery alone （control group）. Twenty to forty 125I seeds （0.5 mCi per seed）, with a total activity in 10-30 mCi, and a matched peripheral dose （MPD） of 60-70 Gy, were implanted under direct visualization. The surgical procedure used in this study was either a radical resection, which involved an esophagectomy through a left thoracotomy with two-field lymphadenectomy, or palliative resection. The postoperative complications were observed and recorded. The location and quality assessment of J25I seeds were assessed using CT scans or X-ray imaging. The short-term efficacy was evaluated according to WHO criteria. The 1, 3, 5 and 7-year survival rates were determined on follow-up. Results： There was no displacement or loss of 125I seeds. The local recurrence rates in the intraoperative 125I seed implantation group and control group were 14.9% and 38.7%, respectively （P 〈 0.05）. An objective response rate of 92% was observed in the seed implant group, which was significantly higher than 0% in the control group （P 〈 0.05）. There was no significant difference between the two groups when comparing of complications （P 〉 0.05）. The 1-year survival rate of the two groups were not significantly different （P 〉 0.05）. However, the 3, 5 and 7-year survival rates in the united 125I group （64%, 55.3% and 8%, respectively） were statistically different from those in the control group （52%, 29.1% and 1.4%,respectively）（P 〈 0.05）. Conclusion： Intraoperative 125I seed implantation is safe and effective for advanced ESCC. Seed implantation may reduce the local recurrence rate and improve survival in patients with ESCC. The MPD of 60-70 Gy, with single 125I seed activity of 0.5 mCi, is reasonable.

Intraoperative permanent implantation of radioactive I-125 seed for local advanced non small lung cancer

Objective： To study the clinical efficacy and methods of permanent implantation of radioactive I-125 seed in surgery for local advanced non small lung cancer （LANSCLC）. Methods： From Apr. 2004 to Apr. 2006, the I-125 seeds were implanted into 30 patients with LANSCLC in surgery. The numbers of seeds were 10-40. The chemotherapy was performed in 10 to 14 days after operation. Results： There was no operative death, and the distribution of seeds and complications were reviewed by CT and X-ray after treatment. The distribution of seeds was satisfactory in all patients. The complete response rate （CR） was 56.6% and the part response （PR） was 26.6%. The overall response rate was 83.3% after 4-24 months of surgery. There was no one occurred radiation pneumonia. Prospective efficacy await further follow-up. Conclusion： Permanent implantation of 1-125 seed in surgery for LANSCLC, is a safe and effective method with mild complications.

Transjugular intrahepatic portosystemic shunt with radioactive seed strand for main portal vein tumor thrombosis with cirrhotic portal hypertension

BACKGROUND Patients with hepatocellular carcinoma complicated with main portal vein tumor thrombosis(mPVTT) and cirrhotic portal hypertension(CPH) have an extremely poor prognosis, and there is a lack of a clinically effective treatment paradigm.AIM To evaluate the efficacy and safety of transjugular intrahepatic portosystemic shunt(TIPS)combined with radioactive seed strand for the treatment of mPVTT patients with CPH.METHODS The clinical data of 83 consecutive patients who underwent TIPS combined with 125I seed strand placement for mPVTT and CPH from January 2015 to December 2018 were retrospectively reviewed. Procedure-related data(success rate, relief of portal vein pressure and CPH symptoms,and adverse events), PVTT response, and patient survival were assessed through a 2-year followup.RESULTS The success rate was 100.0% without perioperative death or procedure-related severe adverse events. The mean portal vein pressure was significantly decreased after the procedure(22.25 ± 7.33mmHg vs 35.12 ± 7.94 mmHg, t = 20.61, P < 0.001). The symptoms of CPH were all effectively relieved within 1 mo. The objective response rate of PVTT was 67.5%. During a mean follow-up of 14.5 ± 9.4 mo(range 1-37 mo), the cumulative survival rates at 6, 12 and 24 mo were 83.1%, 49.7%,and 21.8%, respectively. The median survival time was 12.0 ± 1.3 mo(95% confidence interval: 9.5-14.5). In multivariate Cox regression analysis, body mass index, Child-Pugh grade, cTNM stage,and PVTT response were independent prognostic factors(P < 0.05).CONCLUSION TIPS combined with radioactive seed strand might be effective and safe in treating mPVTT patients with CPH.

Treatment of Unresectable Advanced Gastric Cancer Using lodine-125 Brachytherapy

OBJECTIVE The purpose of the study was to examine the efficacy of treating patients with advanced gastric cancer using iodine-125 （^125Ⅰ） brachytherapy. METHODS Ten patients with unresectable advanced gastric cancer were selected based on their pattern of CT scans. We utilized a brachytherapy planning system to determine the distribution of the ^125Ⅰ seeds, their activity and quantity. The matched peripheral dose （MPD） was 110-135 Gy.^125Ⅰ seeds were implanted in a single plane or biplane by an intraoperative small incision or percutaneous puncture. The postoperative hemogram, CT, KPS, pain-relieving period and survival period were recorded. RESULTS One patient developed a complete response （CR）, 4 patients a partial response （PR）, 3 patients showed no change （NC） and 2 patients developed progressive disease （PD）. The overall response rate （CR＋PR） was 50% （5/10）. The pain-relieving rate was 89% （8/9）. The patients＇ appetite and KPS were improved. The longest survival period was 10 months and median life span was 4 months. There were 8 patients whose seeds fell off resulting in an expulsion rate of 3.8% （26/692）. The patients showed 0-1 degree acute radio-therapeutic side-effects without other symptoms such as abdominal pain, vomitus cruentes or intestinal obstruction etc.CONCLUSION Applying ^125Ⅰ implantation to treat advanced gastric cancer with a reasonable seed distribution can significantly improve clinical symptoms and their quality of life. The radioactive damage is mild. This method can be used as an important supplementary treatment for unresectable advanced gastric cancer.

Iodine-125 interstitial brachytherapy for experimental liver cancer

Objective：To study the effect of iodine-125 interstitial brachytherapy on liver cancer. Methods： Animal model of human liver cancer was established by injecting SMMC-7721 cells cultivated in vitro subcutaneously into the flank of BALB/c nude mice. Nude mice with tumor of 5 mm in diameter were randomly divided into 2 groups （n = 10）. One iodine-125 seed of apparent activity 0.8 mCi was implanted into the center of tumor in treatment group, whereas an inactive seed was implanted in control group. The other 20 nude mice with tumor reaching 10 mm in diameter were also treated as above. The size of tumor was determined weekly after implantation, and pathological examination and blood routine were taken on the 28th day. Results： Tumor growth was obviously inhibited in treatment group of tumor of 5 mm in diameter, and there was statistically significant difference in tumor volume between treatment and control groups （P〈0.01）. Around iodine-125 seed, apparent necrosis of tumor was shown in treatment group, accompanied by karyopyknosis and reduced plasma in residual tumor cells microscopically. Tumor growth was not inhibited in either treatment or control group of tumor of 10 mm in diameter. There was no obvious adverse effect except for decreased white blood cells in treatment groups. Conclusion： There is certain effect of iodine-125 interstitial braehytherapy on liver cancer, which is associated with the size of tumor.

Relationship between miR-7-5p expression and ^(125)I seed implantation efficacy in pancreatic cancer and functional analysis of target genes

Objective The aim of this study was to investigate the relationship between miR-7-5p expression and intertissue-^(125)I irradiation sensitivity in pancreatic cancer tissues and to analyze the function of target genes.Methods Thirty-seven patients with unresectable pancreatic ductal adenocarcinoma(PDAC)treated with radioactive ^(125)I seed implantation were enrolled.RT-PCR was used to detect the expression level of miR-7-5p in cancer tissues and analyze the relationship between miR-7-5p expression and ^(125)I radiation sensitivity.Bioinformatic software and online tools were used to predict the miR-7-5p target genes and analyze their functional annotation and pathway enrichment.Results Radioactive ^(125)I seed implantation was followed up for 2 months.The objective response rate of the miR-7-5p high expression group was 65.0%(13/20),whereas the objective response rate of the miR-7-5p low expression group was 5.88%(1/17),and the difference between the two groups was statistically significant(χ^(2)=13.654,P<0.001).A total of 187 target genes were predicted using three databases.GO functional annotation showed that target genes were mainly involved in cellular response to insulin stimulus,regulation of gene expression by genetic imprinting,cytosol,peptidyl-serine phosphorylation,bHLH transcription factor binding,cargo loading into vesicles,cellular response to epinephrine stimulus,and nucleoplasm.KEGG pathway enrichment analysis showed that target genes were mainly involved in the ErbB signaling pathway,HIF-1 signaling pathway,axon guidance,longevity regulatory pathway,endocrine resistance,glioma,choline metabolism in cancer,and EGFR tyrosine kinase inhibitor drug resistance.Molecular complex detection analysis by Cytoscape revealed that PIGH,RAF1,EGFR,NXT2,PIK3CD,PIK3R3,ERBB4,TRMT13,and C5orf22 were the key modules of miR-7-5p target gene clustering.Conclusion The expression of miR-7-5p in pancreatic cancer tissues positively correlated with the radiosensitivity of ^(125)I seeds.Via targeted gene regulation,miR-7-5p acts on the network of multiple signaling pathways in PDAC and participates in its occurrence and development.Thus,miR-7-5p may become a predictive index of ^(125)I seed implantation therapy sensitivity in PDAC patients.

Continuous Low-dose-rate Irradiation of Iodine-125 Seeds Inhibiting Perineural Invasion in Pancreatic Cancer

Background：Perineural invasion （PNI） is a histopathological characteristic of pancreatic cancer （PanCa）.The aim of this study was to observe the treatment effect of continuous low-dose-rate （CLDR） irradiation to PNI and assess the PNI-related pain relief caused by iodine-125 （125I） seed implantation.Methods：The in vitro PNI model established by co-culture with dorsal root ganglion （DRG） and cancer cells was interfered under 2 and 4 Gy of 125I seeds CLDR irradiation.The orthotopic models of PNI were established,and 125I seeds were implanted in tumor.The PNI-related molecules were analyzed.In 30 patients with panCa,the pain relief was assessed using a visual analog scale （VAS）.Pain intensity was measured before and 1 week,2 weeks,and 1,3,and 6 months after 125I seed implantation.Results：The co-culture of DRG and PanCa cells could promote the growth of PanCa cells and DRG neurites.In co-culture groups,the increased number of DRG neurites and pancreatic cells in radiation group was significantly less.In orthotopic models,the PNI-positive rate in radiation and control group was 3/11 and 7/11;meanwhile,the degrees of PNI between radiation and control groups was significant difference （P 〈 0.05）.At week 2,the mean VAS pain score in patients decreased by 50% and significantly improved than the score at baseline （P 〈 0.05）.The pain scores were lower in all patients,and the pain-relieving effect was retained about 3 months.Conclusions：The CLDR irradiation could inhibit PNI of PanCa with the value of further study.The CLDR irradiation could do great favor in preventing local recurrence and alleviating pain.

A study on the learning curve for a new radioactive seed template retainer assisted by CT-guided radioactive seed implantation for advanced non-small cell lung cancer

Objective:To explore the application of a new radioactive seed template retainer in the learning curve of CTguided 125I seed brachytherapy(CTISBT)for advanced non-small cell lung cancer(NSCLC).Methods:This study retrospectively analyzed the medical records of 60 patients who underwent CTISBT for advanced NSCLC by a single physician between January 2018 and December 2019.The data were sorted in order of admission and divided into three groups according to the order of surgery,group A(cases 1–20),group B(cases 21–40),and group C(cases 41–60).All patients underwent preoperative planning and postoperative dosimetry verification,and the operation time,intraoperative CT scans,postoperative hospital stay,and postoperative complications were compared among the three groups.The quality of life(QOL)score and tumor volume were compared before and 2 months after surgery.Results:There were no statistically significant differences among the three groups in QOL scores,tumor volume,and tumor site before CTISBT assisted by the new radioactive seed template retainer.However,the surgical time differed significantly between the three groups(P<0.01).The operation time was longer in group A than that in groups B and C(P<0.01).There was no significant difference between groups B and C.There were no significant differences in the number of CT scans among the three groups and the length of postoperative hospital stay.The follow-up QOL and tumor volume were significantly reduced at 2 months after surgery compared with those before surgery(P<0.01).Conclusions:The short-term efficacy of the new radioactive seed template retainer-assisted CTISBT was definitive for advanced NSCLC.After the physician had accumulated experience with 20 cases of a new type of radioactive seed template retainer-assisted CTISBT surgery,the follow-up operation time was significantly shortened and the learning curve entered the plateau stage.

Personalized radioprotection in tumor patients after^(125)I seed brachytherapy

Objective:To investigate patient-specific radioprotection mathods for people in close contact with cancer patientstreated by 12I-seed implantation.Methods:The initial dose rates(D_(0))at distances of 30 and 100 cm from 80 patients who had undergone ^(125)I-seed implantation were measured within 24 h of the procedure.The dose rate at t(D_(t))and effective dose(E)were calculated according to the measurad vales of D.The appropriate precaution times for general adult family members,spouses,coworkers,and children or pregnant women were determined,and the relationships between and precaution time for different close-contact groups were derived by curve-fitting the corresponding data.Results:The mean D vahes of 80 patients at distanes of 30 and 100cm were(15.24±11.25)μSv/h and(1.96±2.63)μSv/h,respectively(P<0.05).The mean values and range of precaution time for general adult familymembers,spouses,coworkers,and children or pregnant women were(4.17±16.55),(102.93±49.22),(51.00±61.29),and(34.27±56.90)d(0-90.61),(0-234.01),(0-247.81),and(0-224.69)d,respectively.Furthemore,a logarithmic relationship betwen D and precaution time(Y)was observed for the different groujps.The equations of these relationships were detemined to be Y=-131.569+83.256 lnD_(0) for general adult family mambers,Y=—108.532+83.318 lnD_(0) for spouses,Y=25.470+83.318 lnD,for coworkers,and Y=2.585+83.229 lnD_(0) for children or pregnant women.Conchusions:Some cancer patients treated by ^(125)I-seed brachytherapy emitover-dose levels of γ-rays,necessitatingradiation protection for their close contacts.However,appropriate patient-specific radiation protection fordifferent close contacts can be determined based on the precaution time calculated using the D_(0) value.