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Optimization of Dose Distribution for LINAC-based Radiosurgery with Multiple Isocenters.

Tae Suk SUH ; Sei Chul YOON ; Kyung Sub SHINN ; Yong Whee BAHK

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):351-359.

The current LINAC technique for radiosurgery utilizes a single isocenter approach with multiple noncoplanar arcs. This approach results in spherical dose distributions in the target. Many arteriovenous malformations and tumors suitable for radiosurgical treatment have non-spherical or irregular shapes. The basic approach presented in this paper is to use two or multiple isocenters with standard arcs to shape irregular target volumes through the use of multiple spherical targets. Selection of reasonable irradiation parameters in the first stage is critical to the success of real-time optimization. A useful guideline for optimum isocenter separation and collimator size is developed to shape the target margin uniformly with an desired isodose surface for an elongated target. The implementation of multiple isocenters with three dimensional dose model and application of multiple isocenters approach to several cases are discussed.
Arteriovenous Malformations ; Radiosurgery*

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Development of a New Radiotherapy Technique using the Quasi-conformation Method.

Tae Jin CHOI ; Jin Hee KIM ; Ok Bae KIM

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):343-350.

The quasi-conformation therapy was performed to get a homogeneous dose distributions for irregeular shaped tumor lesion by using the arc moving beam and beam modifying filer which was made by cerrobend alloy (p=9.4g/cc) metal. In our dose calcuation programme, it was fundmentally based on Clarkson's method to calcuate the irregular multi-step block field in rotation therapy. In this study, the expected relative depth doses under multipartial attenuator agree well with measured data at same plane. The results of comparison the dose computation with that of TLD measurement are very closed within +/-5% uncertainties in the irradiation to phantom with quasi-comformation method. And it has shown that irregular typed multi-step filter can be applied to quasi-conformation therapy in high energy radiation plannings.
Alloys ; Radiotherapy*

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The Comparison of the KAPM Dosimetric Protocol (1990) with the TG-21 and Clambda/C(E) Method.

Byong Yong YI ; Eun Kyung CHOI ; Hyesook CHANG

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):337-342.

The Comparison of the KAPM Dosimetric Protocol (1990) with the TG-21 and Clambda/C(E) (ICRU-21 and SCRAD protocol) method is studied. The therapetutic range of radiation (photon 4MV-15MV and electron 6MeV-20MeV)and three kinds of the chambers were used in the water phantom. The Results from TG-21 and KAPM Protocol did not show much differences (less than 1%) throughout the whole energy range; N(D) from KAPM protocol and Ngas from TG-21 showed 0.2% deviation mainly from W/e difference between two protocols. But the results from KAPM protocol (1990) and those from Clambda/C(E) Method showed -1.9+/-0.6%(KAPM protocol is higher) deviation for photom beam and +3.3+/-1% (KAPM protocol is lower) deviation for electron beams.
Water

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The Physical Penumbra of the 6MV X-ray.

Moon June CHO ; Wee Saing KANG

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):333-336.

High energy photon beam margin due to a less side scatter and the other things. But there still remains a penumbra where the dose changes rapidly in the region near the edge of a radiation beam, although it is short in width. It is suggested that the width of the penumbra depends on the source size, distance from source to diaphragm, source to skin distance, and depth in tissue. However, it is also supposed that the other factors influence the penumbra width. In this paper, we investigate changes of the physical penumbra widths according to various field sizes and depths, by using the three dimensional dosimetry system. As a result, we found that as field size and depth increase, the physical penumbra width also increases.
Diaphragm ; Skin

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The Role of Radiation Therapy in Management of Wilms' Tumor.

Mi Sook KIM ; Il Han KIM ; Hyong Geun YUN

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):325-331.

Treatment results of 28 patients with Wilms' Tumor who received radiation therapy at the Department of Therapeutic Radiology, Seoul National University Hospital from 1979 to 1988 were analyzed. The median follow-up period for the survivors was 40 months. The local control and overall survival rate at 3 years were 78.1% and 67.4%, respectively. The local control was not affected by age. The local control rates for favorable histology (FH) and unfavorable histology (UH) were 83.3% and 62.5%, respectively. In FH, the local control rates of stage II and III were not different (83.3% vs 100.0%). In UH, the control rates of stage I/II and stage III were 83.3% and 0%, respectively. Poor local control was correlated with involvement of lymph node (50.0% vs 87.5%). Radiotherapy delayed 10 or more days after operatio resulted in poorer local control than that without delay(p<0.05). Thus radiotherapy contributed to reduction of local recurrence in patients with high risk factor without increased severe comlication. It is suggested that bulky unresectable mass might need a more intensified treatment
Follow-Up Studies ; Humans ; Lymph Nodes ; Radiation Oncology ; Radiotherapy ; Recurrence ; Risk Factors ; Seoul ; Survival Rate ; Survivors ; Wilms Tumor*

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Remote After Loading HDR Brachytherapy for female Urethral Cancer.

Jeong Gil CHO ; Eun Kyung CHOI ; Hyesook CHANG ; Byong Yong YI ; Kwang Hoon KIM ; Jong Goo LEE

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):319-324.

In our institution, a 76-year-old woman with primary urethral carcinoma was treated with remote afterloading high dose rate (HDR) interstitial brachytherapy using micro selectron Ir-192. In this paper, authors described the technical aspect of remote afterloading HDR interstitial brachytherapy for female urethal cancer.
Aged ; Brachytherapy* ; Female* ; Humans ; Urethral Neoplasms*

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The Results of Combined Modality Treatment with Transurethral Resection, Cisplatin and Radiation Therapy for Invasive Bladder Cancer.

Yoon Kyeong OH

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):311-317.

Ten patients with deep muscle-invading bladder carcinoma (clinical stage T3a to T4b) who were not candidates for cystectomy were treated with combined modality treatment with transurethral resection, cisplatin chemotherapy and pelvic irradiation from 1989 through 1990, and were analyzed retrospectively. All patients were not candidates for cystectomy because the trmors were judged unresectable or they were not fit for a radical cystectomy. Of the patients 5 had clinical stage T3a 3 stage T3b and 2 stage T4b disease. The minimum follow-up was 16 months. The complete response rate is 60% for all patients. The complete responses were achieved in 4 of 5(80%) with stage cT3a, in 2 of 3(67%) with stage cT3b and in none of 2(0%) with stage cT4b. The partial responses were achieved in 2, so an overall response rate was 80%. All six patients with grade I or II transitional cell carcinoma showed complete responses. Four patients with higher cancer. Six patients who showed complete responses after treatment. Distant metastases developed in 3 patients : lungs in 2 (cT4b) of those who were never locally free of disease and spine in 1 patient follow-up diarrhea occurred in one which was improved after conservative treatment. On the basis of this analysis it is suggested that combined modality treatment seems to be a tolerable regimen and can be offered with a relatively high probability of success and conservation of bladder function in those with less advanced tumors by clinical stage and low grade.
Carcinoma, Transitional Cell ; Cisplatin* ; Cystectomy ; Diarrhea ; Drug Therapy ; Follow-Up Studies ; Humans ; Lung ; Neoplasm Metastasis ; Retrospective Studies ; Spine ; Urinary Bladder Neoplasms* ; Urinary Bladder*

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Ultrastructural Effects of Irradiation on Squamous Cell Carcinoma of the Uterine Cervix.

Jin Hee KIM ; Ok Bae KIM ; Tae Jin CHOI ; Sang Sook LEE ; Kwan Kyu PARK ; Kun Young KWON ; Young Wook SUH ; Tae Sung LEE ; Tak LEE ; Soon Do CHA

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):303-310.

Nineteen patients with previously untreated invasive squamous cell carcinoma of the uterine cervix were treated by irradiation alone at the Keimyung University Hospital from January, 1990 to July, 1991. The serial samplings of the tissue taken before and during radiation of the uterine cervix were studied by light and electron microscopic examination. Radiation-induced cellular changes, particularly nuclear degeneration was pronounced. The tumor invasion pattern remained unchanged but the number of mitosis and tumor cells decreased. The number of infiltrating inflammatory cells, multinucleated giant cells and karyolitic cells were increased with radiation. Fibrosis was also increased. Electron microscopically, the amount of tonofilament in the tissue samplings was increased in the postirradiated state, but the desmosomes were decreased in numbers. Fibroblasts began to appear after an irradiation dose of 2700cGy. After an irradiation dose of 3600cGy or more, tumor cells were nearly completely degenerated and displaced with mature fibrotic tissue. There was an increase of activated fibroblasts and collagen fibers but a decrease of inflammatory cells in the interstitial tissue. Swelling of the mitochondria and endoplasmic reticulum, loss of intercellular bridges and an increased number of secondary lysosomes were also found with radiation.
Carcinoma, Squamous Cell* ; Cervix Uteri* ; Collagen ; Desmosomes ; Endoplasmic Reticulum ; Female ; Fibroblasts ; Fibrosis ; Giant Cells ; Humans ; Intermediate Filaments ; Lysosomes ; Mitochondria ; Mitosis

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Clinical Significance of Plasma CEA Levels in the Patients with Cervical Carcinoma during Follow-Up.

Sung Beom BAN ; Joo Young KIM ; Myung Sun CHOI ; Joong Yeol RHA ; Min Jae LEE

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):293-301.

Carcinoembryonic antigen (CEA) has been studied in the field of gynecologic malignancy to determine whether it can be used as a tumor marker for early detection of recurrence or evaluation of therapeutic results. From January 1985 through December 1989, a total of 239 cervical cancer patients were entered for an analysis of plasma CEA level in the group with cervical cancer compared to the control group consisting of 65 normal healthy women and 18 women with benign gynecologic disease. Plasma CEA levels appear to be directly related with the tumor extension and as stages advance, the incidence of patients with abnormal plasma CEA levels is increased. Also, there seems to be a little higher incidence of abnormal CEA levels in patients with adenocarcinomas or adenosquamous carcinoma but not statistically significant because of small number of patients. When the patients developed recurrence, plasma CEA levels are markedly elevated in the majority, particularly in patients with hepatic metastases. In conclusion, serial plasma CEA checks could be used to detect recurrence during follow-up after treatment of cervical cancer.
Adenocarcinoma ; Carcinoembryonic Antigen ; Carcinoma, Adenosquamous ; Female ; Follow-Up Studies* ; Genital Diseases, Female ; Humans ; Incidence ; Neoplasm Metastasis ; Plasma* ; Recurrence ; Uterine Cervical Neoplasms

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Analysis of Treatment Failures in Early Uterine Cervical Cancer.

Joo Young KIM ; Kyu Chan LEE ; Myung Sun CHOI

Journal of the Korean Society for Therapeutic Radiology.1991;9(2):285-291.

One hundred and twenty six patients with early uterine cervical cancer who had been treated at department of Radiation Oncology of Korea University Hospital from jan. 1981 to Dec. 1988 were analysed retrospectively by the treatment result and pattern of failures. All patients had stage la to lla disease and were grouped whether they had combination of operation and postop irradiation or radiation therapy alone. 1) Sixty six patients belonged to the combination treatment group and 60 patients to the radiation alone group. 2) Combination group consisted of 18.1%(12/66)stage la, 71.2%(47/66) stage lb and 10.6%(7/66) stage lla patients. There were no stage la, 18.8%(11/60) stage lb and 81.6%(49/60) stage lla patients for RT alone group. 3) There were total 23%(29/126) treatment failures, 13 patients in combination group and 16 patients in RT alone group. In 66 patients of combination group, they were found to have 5 locoregional failures, 7 distant failures and 1 at both sites. In 60 patients of RT alone group, 9 locoreginal failure and 7 distant failures occurred. Eighty six percent(25/29) of total failures appeared within 18 month after completion of treatment. About 60% of the patients with regional recurrences which were located at pelvic side wall or pelvic lymph nodes paesented their recurrent disease after 1 year of completion of treatment, whereas same percent of distant failures appeared within 6 month. 4) In RT alone group, the first sites of distant failure were mostly para-aortic lymph node and/o left supraclavicular lymph node(71.4%, 5/7). In combination group, various sites such as inguinal lymph node, mediastinal lymph node, liver, lung and bone appeared first or at the same time with para-aortic and supraclavicular lymph node metastasis. 5) Logistic regression analysis was done for multivariate analysis of the factors contributing to locoregional and distant failures. In combination group, adequacy of the resection margin and the presence of positive pelvic node were found to be the most significant factors(p=0.0423 & 0.0060 respectively). 6) In RT alone group, less than complete regression of the tumor at the end of treatment was the only significant contributing factor for the treatment failures (p=0.0013) with good likelihood ratio.
Humans ; Korea ; Liver ; Logistic Models ; Lung ; Lymph Nodes ; Multivariate Analysis ; Neoplasm Metastasis ; Radiation Oncology ; Recurrence ; Retrospective Studies ; Treatment Failure* ; Uterine Cervical Neoplasms*

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