The Usefulness of 18F-FDG PET/CT for Predicting the Response of Locally Advanced Rectal Cancer to Neoadjuvant Chemoradiation Therapy / 대한방사선종양학회지

PURPOSE: This study aimed at assessing the value of fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) for predicting the response of locally advanced rectal cancer to neoadjuvant CRT. MATERIALS AND METHODS: Between August 2006 and January 2008, we prospectively enrolled 20 patients with locally advanced rectal cancer and who were treated with neoadjuvant CRT at the Korea Institute of Radiological and Medical Sciences. The treatment consisted of radiation therapy and chemotherapy, and this was followed by curative resection 6 weeks later. All the patients underwent 18F-FDG PET/CT both before CRT and 6 weeks after completing CRT. The measurements of the FDG uptake (SUV(max)), the absolute difference (DeltaSUV(max)) and the percent SUV(max) difference (response index, RI(SUV)) between the pre- and post-CRT 18F-FDG PET/CT scans were assessed. The measurements of the metabolic volume, the absolute difference (Delta metabolic volume) and the percent metabolic volume difference (response index, RI(metabolic volume)) were also assessed. RESULTS: Of the 20 patients who underwent surgery, 11 patients (55%) were classified as responders according to Dworak's classification. The post-CRT SUV(max) was significantly lower than the pre-CRT SUV(max). However, there were no significant differences in the SUV(max) and the metabolic volume reduction between the responders and non-responders. We used a minimum SUV(max) reduction of 67% as the cut-off value for defining a response, with a sensitivity of 45.5%, a specificity of 88.9%, a positive predictive value of 77% and a negative predictive value of 53.8%. CONCLUSION: Although there were no statistically significant results in this study, other studies have revealed that 18F-FDG PET/CT has the potential to assess the tumor response to neoadjuvant CRT in patients with locally advanced rectal cancer.

Clinical Characteristics of Radiation Oncology in Korea during Past 10 Years

To understand trends in the clinical characteristics of radiation oncology over the last 10 yr in Korea, annual survey questionnaires were sent to all of Korean radiation oncology facilities since 1990. Questionnaires addressed basic radiation therapy facilities and the clinical information. Responses were obtained from all facilities, and data collected from 1997 to 2006 was analyzed. The numbers of new patients that have undergone radiation therapy and the numbers of hospitals with a department of radiation oncology have steadily increased over the past 10 yr, and totaled 37,215 patients and 60 hospitals, respectively, in 2006. However, the proportion of patients irradiated among total cancer patients has remained below 30% over the last 10 yr. The numbers of prostate cancer, breast cancer, and hepatoma have increased by more than 3 fold over the past 10 yr. Moreover, the percentage of irradiated patients treated by brachytherapy was 10.3% in 1997, but this gradually fell to only 4.2% in 2006. The information collected described the role played by radiation oncology in Korea. Continuous surveys are required to enable trends to be detected.

Accelerated Hyperfractionated Radiotherapy for Locally Advanced Uterine Cervix Cancers / 대한방사선종양학회지

PURPOSE: To assess the efficacy of the use of accelerated hyperfractionated radiotherapy (AHRT) for locally advanced uterine cervix cancers. MATERIALS AND METHODS: Between May 2000 and September 2002, 179 patients were identified with FIGO stage IIB, IIIB, and IVA cancers. Of the 179 patients, 45 patients were treated with AHRT (AHRT group) and 134 patients were treated with conventional radiotherapy (CRT group), respectively. Patients undergoing the AHRT regimen received a dose of 30 Gy in 20 fractions (1.5 Gyx2 fractions/day) to the whole pelvis. Subsequently, with a midline block, we administered a parametrial boost with a dose of 20 Gy using 2 Gy fractions. Patients also received two courses of low-dose-rate brachytherapy, up to a total dose of 85~90 Gy to point A. In the CRT group of patients, the total dose to point A was 85~90 Gy. The overall treatment duration was a median of 37 and 66 days for patients that received AHRT and CRT, respectively. Statistical analysis was calculated by use of the Kaplan-Meier method, the log-rank test, and Chi-squared test. RESULTS: For patients that received cisplatin-based concurrent chemotherapy and radiotherapy, the local control rate at 5 years was 100% and 79.2% for the AHRT and CRT group of patients, respectively (p=0.028). The 5-year survival rate for patients with a stage IIB bulky tumor was 82.6% and 62.1% for the AHRT group and CRT group, respectively (p=0.040). There was no statistically significant difference for severe late toxicity between the two groups (p=0.561). CONCLUSION: In this study, we observed that treatment with AHRT with concurrent chemotherapy allows a significant advantage of local control and survival for locally advanced uterine cervix cancers.

Distortion of the Dose Profile in a Three-dimensional Moving Phantom to Simulate Tumor Motion during Image-guided Radiosurgery / 대한방사선종양학회지

PURPOSE: Respiratory motion is a considerable inhibiting factor for precise treatment with stereotactic radiosurgery using the CyberKnife (CK). In this study, we developed a moving phantom to simulate three-dimensional breathing movement and investigated the distortion of dose profiles between the use of a moving phantom and a static phantom. MATERIALS AND METHODS: The phantom consisted of four pieces of polyethylene; two sheets of Gafchromic film were inserted for dosimetry. Treatment was planned to deliver 30 Gy to virtual tumors of 20, 30, 40, and 50 mm diameters using 104 beams and a single center mode. A specially designed robot produced three-dimensional motion in the right-left, anterior-posterior, and craniocaudal directions of 5, 10 and 20 mm, respectively. Using the optical density of the films as a function of dose, the dose profiles of both static and moving phantoms were measured. RESULTS: The prescribed isodose to cover the virtual tumors on the static phantom were 80% for 20 mm, 84% for 30 mm, 83% for 40 mm and 80% for 50 mm tumors. However, to compensate for the respiratory motion, the minimum isodose levels to cover the moving target were 70% for the 30~50 mm diameter tumors and 60% for a 20 mm tumor. For the 20 mm tumor, the gaps between the isodose curves for the static and moving phantoms were 3.2, 3.3, 3.5 and 1.1 mm for the cranial, caudal, right, and left direction, respectively. In the case of the 30 mm tumor, the gaps were 3.9, 4.2, 2.8, 0 mm, respectively. In the case of the 40 mm tumor, the gaps were 4.0, 4.8, 1.1, and 0 mm, respectively. In the case of the 50 mm diameter tumor, the gaps were 3.9, 3.9, 0 and 0 mm, respectively. CONCLUSION: For a tumor of a 20 mm diameter, the 80% isodose curve can be planned to cover the tumor; a 60% isodose curve will have to be chosen due to the tumor motion. The gap between these 80% and 60% curves is 5 mm. In tumors with diameters of 30, 40 and 50 mm, the whole tumor will be covered if an isodose curve of about 70% is selected, equivalent of placing a respiratory margin of below 5 mm. It was confirmed that during CK treatment for a moving tumor, the range of distortion produced by motion was less than the range of motion itself.

Locally Advanced, Unresectable Pancreatic Cancer Treated by Stereotactic Radiation Therapy / 대한방사선종양학회지

PURPOSE: In order to find out whether stereotactic radiation therapy (RT) using CyberKnife (CK) could improve survival rate and lower acute toxicity compared to conventional RT. MATERIALS AND METHODS: From April 2003 through April 2004, 19 patients with Eastern Cooperative Oncology Group (ECOG) performance status 80 cc (p-value80 cc showed better survival rate. CONCLUSION: In terms of survival, the efficacy of stereotactic radiation therapy using CK was found to be superior or similar to other recent studies achieved with conventional RT with intensive chemotherapy, high dose conformal RT, intraoperative RT (IORT), or intensity modulated RT (IMRT). Furthermore, severe toxicity was not observed. Short treatment time in relation to the short life expectancy gave patients more convenience and, finally, quality of life would be increased. Consequently, this could be regarded as an effective novel treatment modality for locally advanced, unresectable pancreas cancer. PTV would be a helpful prognostic factor for CK.

The Clinicopathological Factors That Determine a Local Recurrence of Rectal Cancers That Have Been Treated with Surgery and Chemoradiotherapy / 대한방사선종양학회지

PURPOSE: To evaluate the pathological prognostic factors related to local recurrence after radical surgery and adjuvant radiation therapy in advanced rectal cancer. MATERIALS AND METHODS: Fifty-four patients with advanced rectal cancer who were treated with radical surgery followed by adjuvant radiotherapy and chemotherapy between February 1993 and December 2001 were enrolled in this study. Among these patients, 14 patients experienced local recurrence. Tissue specimens of the patients were obtained to determine pathologic parameters such as histological grade, depth of invasion, venous invasion, lymphatic invasion, neural invasion and immunohistopathological analysis for expression of p53, Ki-67, c-erb, ezrin, c-met, phosphorylated S6 kinase, S100A4, and HIF-1 alpha. The correlation of these parameters with the tumor response to radiotherapy was statistically analyzed using the chi-square test, multivariate analysis, and the hierarchical clustering method. RESULTS: In univariate analysis, the histological tumor grade, venous invasion, invasion depth of the tumor and the over expression of c-met and HIF-1 alpha were accompanied with radioresistance that was found to be statistically significant. In multivariate analysis, venous invasion, invasion depth of tumor and over expression of c-met were also accompanied with radioresistance that was found to be statistically significant. By analysis with hierarchical clustering, the invasion depth of the tumor, and the over expression of c-met and HIF-1 alpha were factors found to be related to local recurrence. Whereas 71.4% of patients with local recurrence had 2 or more these factors, only 27.5% of patients without local recurrence had 2 or more of these factors. CONCLUSION: In advanced rectal cancer patients treated by radical surgery and adjuvant chemo-radiation therapy, the poor prognostic factors found to be related to local recurrence were HIF-1 alpha positive, c-met positive, and an invasion depth more than 5.5 mm. A prospective study is necessary to confirm whether these factors would be useful clinical parameters to measure and predict a radio-resistance group of patients.

The Development of Quality Assurance Program for CyberKnife / 대한방사선종양학회지

PURPOSE: Standardization quality assurance (QA) program of CyberKnife for suitable circumstances in Korea has not been established. In this research, we investigated the development of QA program for CyberKnife and evaluation of the feasibility under applications. MATERIALS AND METHODS: Considering the feature of constitution for systems and the therapeutic methodology of CyberKnife, the list of quality control (QC) was established and divided dependent on the each period of operations. And then all these developed QC lists were categorized into three groups such as basic QC, delivery specific QC, and patient specific QC based on the each purpose of QA. In order to verify the validity of the established QA program, this QC lists was applied to two CyberKnife centers. The acceptable tolerance was based on the undertaking inspection list from the CyberKnife manufacturer and the QC results during last three years of two CyberKnife centers in Korea. The acquired measurement results were evaluated for the analysis of the current QA status and the verification of the propriety for the developed QA program. RESULTS: The current QA status of two CyberKnife centers was evaluated from the accuracy of all measurements in relation with application of the established QA program. Each measurement result was verified having a good agreement within the acceptable tolerance limit of the developed QA program. CONCLUSION: It is considered that the developed QA program in this research could be established the standardization of QC methods for CyberKnife and confirmed the accuracy and stability for the image-guided stereotactic radiotherapy.

Statistics for Department of Radiation Oncology (1999~2001) / 대한방사선종양학회지

No abstract available.

Dosimetry of the Low Fluence Fast Neutron Beams for Boron Neutron Capture Therapy / 대한방사선종양학회지

PURPOSE: For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. METHOD AND MATERIALS: For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, EIC-1 ion chambers manufactured by A-150 plastic and used IC-17M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was 5 cc per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and there results were compared with measured results. RESULTS: The absorbed dose of fast neutron beams was 6.47x10-3 cGy per 1 MU at the 4 cm depth of the water phantom, which is assumed to be effective depth for BNCT. The magnitude of gamma contamination intermingled with fast neutron beams was 65.2+/-0.9% at the same depth. In the dose distribution according to the depth of water, the neutron dose decreased linearly and the gamma dose decreased exponentially as the depth was deepened. The factor expressed energy level, D20/D10, of the total dose was 0.718. CONCLUSION: Through the direct measurement using the two ion chambers, which is made different wall materials, and computer calculation of isodose distribution using MCNP simulation method, we have found the dose characteristics of low fluence fast neutron beams. If the power supply and the target material, which generate high voltage and current, will be developed and gamma contamination was reduced by lead or bismuth, we think, it may be possible to accelerator-based BNCT.

Brachytherapy in the Treatment of Head and Neck Cancer / 대한방사선종양학회지

Brachytherapy has been proved to be an effective method for the purpose of increasing radiation dose to the tumor and reducing the dose to the surrounding normal tissue. In head and neck cancer, the rationale of brachytherapy is as follows; Firstly, early small lesion is radiocurative and the major cause of failure is local recurrene. Seondly, it can diminish evidently the dose to the normal tissue especially masseteric muscle and salivary gland. Thirdly, the anatomy of head and neck is suitable to various technique of brachytherapy. On background of accumulated experience of LDR iridium brachytherapy of head and neck cancer for the last 15 years, the author reviewed the history of radioisotope therapy, the characteristics of radionuclides,and some important things in the method, clinical technique and treatment planning. The author analyzed the clinical result of 185 cases of head and neck cancer treated in the Korea Cancer Center Hospital. Finally the fu ture prospect of brachytherapy of head and neck cancer is discussed.

Primary CHOP Chemotherapy Followed by Involved Field Radiation Therapy in Clinical Stage I or II Aggressive Non-Hodgkin's Lymphomas / 대한암학회지

PURPOSE: Although radiation therapy had been the treatment of choice for localized non-Hodgkin's lymphoma(NHL), recent studies have revealed that treatment result after radiation therapy alone is not successful for localized aggressive NHL, if it is not pathologically but clinically staged. A prospective phase II trial was conducted to evaluate the therapeutic results of 4 cycles of CHOP chemotherapy followed by involved field radiation therapy in clinically staged localized aggressive NHL. MATERIALS AND METHODS: Patients with a diagnosis of aggressive NHL(all intermediate grade and immunoblastic histology in NCI working formulation), Ann Arbor stage I or II without poor prognostic factors(presence of B symptoms, bulky diseases, or 2 or more extranodal involvement) were treated with 4 cycles of CHOP(cyclophosphamide, doxorubicin, vincristine, prednisolone) followed by involved field radiation therapy of 3,000~6,000(median: 4,500) cGy. RESULTS: Between April 1990 and March 1995, 62 consecutive patients entered this trial. Forty six patients with measurable diseases were evaluable for response. Complete response was achieved in 41(89.1%) patients after CHOP chemotherapy and 4 more patients after subsequent radiation therapy, making total CR rate of 98%. Progression free survival(PFS) of all 62 patients were 2.2+~73+ months and 5 year PFS rate was 64.6%. Overall survival(OS) were 2.4+~75+ months and 5 year OS rate was 75.2%. Old age (> 60) was the only significant prognostic factor, which-affected overall survival negatively. Treatment was relatively well tolerated, but 3 patients died associated with treatment. CONCLUSIONS: Four cycles of CHOP chemotherapy followed by involved field radiation therapy is highly curative and safe treatment for clinically staged, localized aggressive NHLs.

Phase II Study of Concurrent Chemotherapy with Etoposide and Cisplatin (EP) and Radiation Therapy for Unresectable Stage III Non-small Cell Lung Cancer / 결핵

BACKGROUND: Various combinations of treatment modalities have been reported in stage III non-small cell lung cancer (NSCLC), however, the standard treatment modality has not established yet. Recently, the efficacy of concurrent chemotherapy and radiation therapy has been reported in locally advanced lung cancer. We evaluate the response rate, toxicity, arid survival of concurrent chemotherapy with etoposide and cisplatin(EP) arid radiation therapy for unresectable stage III NSCLC. METHODS: Between October 1995 and December 1996, 32 patients with histologically proven unresectable stage III NSCLC without, malignant pleural effusion were entered into this study. Twenty-nine patients were eligible for the response, survival, and toxicity analysis. Induction was two cycles of chemotherapy with etoposide arid cisplatin plus concurrent chest RT to 4500cGy. Resection was attempted if the clinical response offered surgical resectability. Boost radiation therapy upto 5940cGy and one cycle of EP were performed if the disease were stable or responsive but still unresectable. RESULTS: Of 29 eligible patients, 22(75.9%) showed partial response(PR). The progression free interval was 6.3months(range 1.1 to 19.5months). Surgical resection was performed in one patient The median survival was l2.1months and one-year survival rate was 50.6%. The major toxicity was leukopenia(> or = grade 3,46%) Thrombocytopenia over grade 3 was found in 1%. Radiation pneumonitis occurred in 13 patients(46%). CONCLUSION: Concurrent chemotherapy(EP) pins radiotherapy was effective and tolerable in the treatment of unresectable stage III NSCLC.

Analysis of prognostic factors in patients with Carcinoma of Uterine Cervix / 대한치료방사선과학회지

PURPOSE: The authors conducted a retrospective analysis of patients with the carcinoma of uterine cervix treated with curative radiation therapy to evaluated the prognostic factors that would affect the results of the therapy and to get the critical ideas in determining more aggressive treatment schedule. METHODS AND MATERIALS: From January 1987 to December 1988, Four hundreds and sixty patients with uterine cervical carcinomas treated with radiotherapy at KCCH were registered to this retrospective study. One hundred and three patients were treated with external radiation therapy alone, and 357 patients were treated with external radiation followed by low dose rate intracavitary radiation therapy. He follow-up rate was 88% and median follow-up duration was 48 months. RESULTS: The overall 5 year survival rate of the patients was 67.7%, and when classified by FIGO stages, 5 year survival rates were 81.2%, 76.3%, 73.1%, 50%, 52.3%, 11.5% for stages Ib, IIa, IIb, IIIa, IIIb, IVa respectively. Tumor size(p=0.0002), endocervical growth pattern(p=0.003), lymph node invasion(p=0.0001), mean hemoglobin level(p=0.0001), and pathologic cell type(p=0.0001) were significant prognostic factors and decrease in survival for young age patient group was marginally important(p=0.03). CONCLUSION: Significant prognostic factors I the radiation therapy of the uterine cervical carcinoma were tumor size, growth pattern of tumor, lymph node invasion, pathologic cell type, hemoglobin level of patients during treatment and lower survival rate in young age group was obvious, too. Patients with large size tumor(> or =4cm), especially combined with endocervical growth patterns or advanced stages(III or more) need more aggressive treatment to improve the outcome of treatment. And positive feature of lymph node invasion affected the result of therapy, so improvement in the diagnostic and therapeutic trial is essential.

The Effects of Akaloid Fraction of Korean Ginseng on the Radiation-Induced DNA Strand Breaks / 대한치료방사선과학회지

PURPOSE: To investigate the effect of alkaloid fraction from Korean ginseng on radiation-induced DNA double strand breaks(dsb) formation and repair in murine lymphocytes. MATERIALS AND METHODS: We used the neutral filter elution technique to assay 60 Co gamma ray-induced DNA double strand breaks formation and repair in C57BL/6 mouse spleen lymphocytes for evaluation the dose-response relationship in the presence of alkaloid fraction as a radioprotective agent. The lymphocytes were stimulated with phytohemagglutinin (PHA, 2 mug/ml) to label 3 [H]-thymidine. Isotope-labelled lymphocytes in suspension were exposed to 100 Gy at 0degree C in the alkaloid fraction-treated group and elution procedure was performed at pH 9.6. The extents of formation of radiation-induced DNA double strand breaks and repair were compared respectively via strand scission factor (SSF) and relative strand scission factor (RSSF). RESULTS: Alkaloid fraction reduced the formation of double strand breaks with dose modification factor of 2.15, compared to control group. Rejoining of DNA dsb appeared to take place via two components. The first fast component was completed within 20.4 minutes, but the second slow component was not completed until 220.2 minutes after irradiation. About 30% of dsb formed by irradiation was ultimately unrejoined despite the administration of alkaloid fraction. The administration of alakaloid fraction had a great effect on the second slow component of repair ; the half-time of fast component repair was not changed, but that of slow component was 621.8 minutes. CONCLUSION: Neutral filter elution assay proved to be a very effective method to quantitate the extents of DNA dsb formation and its repair. By using this technique, we were able to evaluate the efficiency of alkaloid fraction from Korean ginseng as a valuable radioprotector. Alkaloid fraction can be used prophylactically to prevent or ameliorate the severe radiation damages in workers and neighbors aound the atomic power plants. For more refined study, however, more advanced purification of alkaloid fraction will be neended in the near future.

The Results of Primary Radiotherapy following Breast-Conserving Surgery for Early Breast Cancer / 대한치료방사선과학회지

PURPOSE: Primary radiation therapy following breast-conserving surgery has been an accepted alternative to mastectomy during the past 2 decades. In this country, however, the practice of conservative therapy for early invasive breast cancer has not been generalized yet. The purpose of this report was to evaluate the results and complications of breast conservation therapy in Korean Cancer Center Hospital(KCCH) MATERIALS AND METHODS: From January 1987 to December 1989, 45 patietns with early breast cancer treated with conservative treatment in KCCH were studied retrospectively. Median follow up was 54 months(range, 4 to 82 months). All patients received partial mastectomy (biopsy, tumorectomy, or quadrantectomy) and radiation therapy. Twenty eight patients received axillary dissection. The breast was treated with two poosing tangential fields (total 50 Gy or 50.4 Gy in 5 weeks with daily target dose of 2 Gy or 1.8 Gy). Thirty patients received chemotherapy before and after radiotherapy. Eleven patients received hormonal therapy. RESULTS: Five-year survival rate, 5-year disease free survival rate and 5-year local control rate were 87.2%, 86.5% and 97.6%, respectively. Administration of systemic Therapy (chemotherapy or hormonal therapy) correlated with good prognosis but statistically not significant (0.05 < p < 0.01). The sever late complication rate was 8.9%. CONCLUSION: Primary radiation therapy following breast-conserving surgery for early breast cancer is an alternative treatment comparing to radical treatment. Long term follow-up and more patients collection is needed to evaluate the prognostic factor and cosmetic outcome.

Evaluation of DNA Double Strand Breaks in Human and Mouse Lymphocyte Following gamma-Irradiation / 대한치료방사선과학회지

The evaluation of radiation-induced DNA double strand breaks(DSB) was made following irradiation of human lymphocytes, murille lymphocytes and EL-4 leukemia cells over a wide dose range of 60Co g-rays. In lipopolysacchande(LPS) or phytohemagglutinin(PHA)-stimulated murine lymphocytes, the slopes of the strand scission factor(SSF) revealed that lymphocytes with LPS increased DNA DSB formation by a factor of 1.432 (p<0.005). Furthermore, strand break production was relatively inefficient in the T lymphocytes compared to the B lymphocytes. And EL-4 leukemia cells were found to form significantly more DNA DSB to a greater extent than normal lymphocytes (p<0.705). The in vitro studies of the intrinsic radiosensitivity between human lymphocytes and murine lymphocytes showed similar phasic kinetics. However, murine lymphocytes were lower in DNA DSB formation and higher in the relative radiation dose of 10 percent DNA strand breaks at 3.5 hours following g-irradiation than human lymphocytes. Though it is difficult to interpret these results, these differences may be result from environmental and genetic factors. From our data, if complementary explanations for this difference will be proposed, the differences in the dose-effect relationship for the induction of DSB between humans and mice must be related to interspecies variations in the physiological condition of the peripheral blood in vitro and not to differences in the intrinsic radiation sensitivity of the lymphocytes. These results can be estimated on the basis of dose-effect correlation enabling the interpretation of clinical response and the radiobiological parameters of cytometrical assessment.

Frequency of Micronuclei in Lymphocytes Following Gamma and Fast-neutron Irradiations / 대한치료방사선과학회지

The dose response of the number of micronuclei in cytokinesis-blocked (CB) lymphocytes after in vitro irradiation with -rays and neutrons in the 5 dose ranges was studied for a heterogeneous population of 4 donors. One thousand binucleated cells were systematically scored for micronuclei. Measurements performed after irradiation showed a dose-dependent increase in micronuclei(MN) frequency in each of the doctors studied. The dose-response curves were analyzed by a linear-quadratic model, frequencies per 1000 CB cells were (0.31+/-0.049) D+(0.0022+/-0.0002) D2+(13.19+/-1.854) (r2=1.000, X2=0.7074, p=0.95) following irradiation, and (0.99+/-0.528) D+(0.0093+/-0.0047) D2+(13.31+/-7.309) (r2=0.996, X2=7.6834, p=0.11) following neutrons irradiation (D is irradiation dose in cGy). The relative biological effectiveness (RBE) of neutrons compared with -rays was estimated by best fitting linear-quadratic model. In the micronuclei frequency between 0.05 and 0.8 per cell, the RBE of neutrons was 2.37+/-0.17. Since the MN assay is simple and rapid, it may be a good tool for evaluating the y-ray and neutron response.

Combined Effects of Gamma-irradiation and Hyperthermia on the Human Cell Lines for Various Temperatures and Time Sequences / 대한치료방사선과학회지

We tried to establish the theoretical basis of clinical use of combined modality of hyperthermia and radiation therapy. For this purpose, we made an in vitro experiment in order to get the synergistic and/or additive effects on the cell killing of hyperthermia combined with radiation therapy by using the microwave-hyperthermia machine already installed at our department. In our experiment, we use two human cell lines: MKN-45(adenocarcinoma of stomach) and K-562(leukemia cell lines). In cases of combined treatments of hyperthermia and gamma-irradiation, the therapeutic effect was the highest in the simultaneous trial. Hyperthermia after gamma irradiation showed slightly higher therapeutic effect than that before irradiation without significant difference, but its effect was the same in the interval of 6 hours between hyperthermia and irradiation. The higher temperature and the longer treatment time were applied, the higher therapeutic effects were observed. We could observe the thermoresistance by time elapse at 43 degree C. When hyperthermia was done for 30 minutes at the same temperature, thermal enhancement ratio(TER) at D0.01(dose required surviving fraction of 0.01) were 2.5+/-0.08, 3.75+/-0.18, and 5.0+/-0.15 at 43 degree C, 44 degree C, and 45 degree C respectively in K-562 leukemia cell lines. Our experimental data showed that more cell killing effect can be obtained in the leukemia cell lines, although they usually are known to be radiosensitive, when treated with combined hyperthermia and radiation therapy. Furthermore, our data show that leukemia cell lines May have various intrinsic radiosensitivity, especially in vitro experiments. The magnitude of cell killing effect, however, will be less than that of MKN-45.

Neutron Therapy of Unresectable and Recurrent Rectal Cancer / 대한치료방사선과학회지

Total of 53 patients of unresectable and recurrent rectal cancer treated with neutron beam during the period from Oct. 1987 to Apr. 1992 were analyzed. Dose fractionation for the neutron only group was 1.5 Gy per fraction, 3 fraction per week, 21 Gy/41/2 wks for 42 patients out of 53(76%). Neutron only but modified fractionation schedule (10% more or less of total dose) was applied for 9 patients, and mixed team (neutron boost) was for 4 patients. Complete tumor response was obtained in 40 patients(76% response rate). Local control rate was 28 out of 53(53%). Statistically significant better prognostic factors for local control were age below 49 years old (15/22, 68%) than above 50 years old (13/31, 42%), male (20/32, 63%) than female(8/21, 38%), tumor size less than 5 cm and non-metastatic(16/24, 67%) than size more than 5 cm or metastatic(12/29, 4l%). Major complication had developed in 7 patients (13%). Two year overall survival rate by Kaplan-Meier method was 30%, but it was rised to, 47% when the tumor was less than 5cm non-metastatic.

Radiotherapy for Oral Cavity Cancer / 대한치료방사선과학회지

Eighty five patients of oral cavity cancer, treated with radiation at the Department of Therapeutic Radiology, Korea Cancer Center Hospital, during the period from March 1985 to September 1990 were analyzed retrospectively. Among 85 patients, 37 patients were treated with radiation only and 48 patients were treated with radiation following surgery And 70 patients received external irradiation only by 60Co with or without electron, the others were 7 patients for external irradiation plus interstitial implantation and 8 patients for external irradiation plus oral cone electron therapy. Primary sites were mobile tongue for 40 patients, mouth floor for 17 patients, palate for 12 patients, gingiva including retromolar trigone for 10 patients, buccal mucosa for 5 patients, and lip for 1 patient. According to pathologic classification, squamous cell carcinoma was the most common (77 patients). According to AJC TNM stage, stage I + II were 28 patients and stage III+IV were 57 patients. Acturial overall survival rate at 3 years was 43.9%, 3 year survival rates were 60.9% for stage I + II, and 23.l% for stage III+IV, respectively. As a prognostic factor, primary T stage was a significant factor (p<0.01). The others, age, location, lymph node metastasis, surgery, radiation dose, and cell differentiation were not statistically significant. Among those factors, radiation plus surgery was more effective than radiation only in T3+T4 or in any N stage although it was not statistically sufficient(p<0.1). From those results, it was conclusive that definitive radiotherapy was more effective than surgery especially in the view of pertainig of anatomical integrity and function in early stage, and radiation plus surgery was considered to be better therapeutic tool in advanced stage.