PURPOSE: LiF TLD has a problem to be used in vivo dosimetry because of the toxic property of LiF. The aim of this study is to develop new dosimeter with LiF TLD to be used in vivo dosimetry. MATERIALS AND METHODS: We designed and manufactured the teflon box(here after TLD holder) to put TLD in. The external size of TLD holder is 4x4x1 mm3. To estimate the effect of TLD holder on TLD response for radiation, the linearity of TLD response to nominal dose were measured for TLD in TLD holder. Measurement were performed in the 10 MV x-ray beam with LiF TLD using a solid water phantom at SSD of 100 cm. Percent Depth Dose (PDD) and Tissue-Maximum Ratio (TMR) with varying phantom thickness on TLD were measured to find the effect of TLD holder on the dose coefficient used for dose calculation in radiation therapy. RESULTS: The linearity of response of TLD in TLD holder to the nominal dose was improved than TLD only used as dosimeter. And in various measurement conditions, it makes a marginnal difference between TLD in TLD holder and TLD only in their responses. CONCLUSION: It was proven that the TLD in TLD holder as a new dosimetry could be used in vivo dosimetry.
Polytetrafluoroethylene ; Silver Sulfadiazine ; Water

PURPOSE: An investigation has been carried out on the factors which affect the response reading of thermoluminescent dosimeters (TLD-100) loaded with thin material in high energy photon. The aim of the study was to assess the energy response of TLD-100 to the therapeutic ranges of photon beam. MATERIALS AND METHODS: In this technique, TLD-100 (abbreviated as TLD) chips and three different thin material (Tin, Gold, and Tissue equivalent plastic plate) which mounted on the TLD chip were used in the clinical photon beam. The thickness of each metal plates was 0.1 mm and TE plastic plate was 1 mm thick. These compared with the photon energy dependence of the sensitivities of TLD (normal chip), TLD loaded with Tin or Gold plate, for the photon energy range 6 MV to 15 MV, which was of interest in radiotherapy. RESULTS: The enhancement of surface dose in the TLD with metal plate was clearly detected. The TLD chips with a Gold plate was found to larger response by a factor of 1.83 in 10 MV photon beam with respect to normal chip. The sensitivity of TLD loaded with Tin was less than that for normal TLD and TLD loaded with Gold. The relative sensitivity of TLD loaded with metal has little energy dependence. CONCLUSION: The good stability and linearity with respect to monitor units of TLD loaded with metal were demonstrated by relative measurements in high energy photon (6~15 MV) beams. The TLD laminated with metals embedded system in solid water phantom is a suitable detector for relative dose measurements in a small beam size and surface dose.
Metals ; Plastics ; Radiotherapy ; Tin ; Water

From May 1979 through December 1981 a total of 524 patients with carcinoma of the uterine cervix were treated by radiation therapy with curative intent. Among the 524 patients, 356 were treated with a high-dose-rate (HDR), remote-controlled, afterloading intracavitary irradiation (ICR) system using a cobalt source (Ralstron), and 168 patients received a low-dose-rate (LER) ICR using a radium source. External beam irradiation with a total dose of 40-50 gy to the whole pelvis followed by intracavitary irradiation with a total dose or 30-39 gy in 10-13 fractions to point A was the treatment protocol ICR was given three times a week with a dose of 3 gy per fraction. Five-year actuarial survival rates in the HER-ICR group were 77.6% in stage IB (N=20), 68.2% in stage II (N=182), and 50.9% in stage III (N=148). In LDR-ICR group, 5-year survival rates were 87.5% in stage IB (N=22), 66.3% in stage II (N=91), and 55.4% in stage III (N-52). Survival rates showed a statistically significant difference by stage, but there was no significant difference between the two ICR groups. Late bowel complications after radiotherapy were noted in 3.7% of the HDR-ICR group and 8.4% of the LDR-ICR group. There was no severe complication requiring surgical management. The incidence of bladder complications was 1.4% in the HDR-ICR group and 2.4% in the LDR-ICR group. The application of HDR-ICR was technically simple and easily performed on an outpatient basis without anesthesia, and the patients tolerated it very well. Radiation exposure to personnel was virtually nil in contrast to that of LDR-ICR. Within a given period of time, more patients can be treated with HDR-ICR because of the short treatment time. Therefore, the HDR-ICR system is highly recommended for a cancer center, particularly one with a large number of patients to be treated. In order to tachieve an improved outcome, however, the optimum dose-fractionation schedule of HDR-ICRand optimum combination of intracavitary irradiation with external beam irradiation should be determined through an extensive protocol study with different treatment regimens.
Anesthesia ; Appointments and Schedules ; Cervix Uteri* ; Clinical Protocols ; Cobalt ; Female ; Humans ; Incidence ; Outpatients ; Pelvis ; Radiotherapy ; Radium ; Survival Rate ; Urinary Bladder

Increasing frequency of skin cancer, mycosis fungoides, Kaposi's sarcoma etc, it need to treatment dose planning for total skin electron beam (TSEB) therapy. Appropriate treatment planning for TSEB therapy is needed to give homogeneous dose distribution throughout the entire skin surface. The energy of 6 MeV electron from the 18 MeV medical linear accelerator was adapted for superficial total skin electron beam therapy. The energy of the electron beam was reduced to 4.2 MeV by a 0.5cm x90cm x180cm acryl screen placed in a feet front of the patient. Six dual field beam was adapted for total skin irradiation to encompass the entire body surface from head to toe simultaneously. The patients were treated behind the acryl screen plate acted as a beam scatterer and contained a parallel-plate shallow ion chamber for dosimetry and beam monitoring. During treatment, the patient was placed in six different positions due to be homogeneous dose distribution for whole skin around the body. One treatment session delivered 400 cGy to the entire skin surface and patients were treated twice a week for eight consecutive weeks, which is equivalent to TDF value 57. Instrumentation and techniques developed in determining the depth dose, dose distribution and bremsstrahlung dose are discussed.
Foot ; Head ; Humans ; Mycosis Fungoides ; Particle Accelerators ; Sarcoma, Kaposi ; Skin Neoplasms* ; Skin* ; Toes

PURPOSE: Uterine cervical carcinoma is the most common cancer in Korean women. We evaluated the accuracy of magnetic resonance (MR) imaging in determining the stage and extent of disease in cervical carcinoma. MATERIALS AND METHODS: From January 1994 through December 1996, in all 35 patients, MR imaging was performed before any operative procedure. With a 1.5T superconducting magnet, TR (repetition time)/TE (echo time) of 483/9msec for T1-weighted images and 3750/98msec for T2-weighted images were used. All patients underwent radical hysterectomy or total abdominal hysterectomy and had detailed histologic evaluation. MR image were reviewed and compared with pathologic findings on the presence of tumor size, depth of stromal invasion and vagina extension. RESULTS: The accuracy of MRI in determination of stage was 74%. Its accuracy was 60% for the assessment of tumor size. Tumor size was underestimated in 6 patients (17%) and overestimated in 8 patients (23%). Tumor infiltration into the stroma was classified as no, partial, complete. The accuracy of MRI in cervical stromal invasion was 66%. CONCLUSION: MR is a relatively promising method for staging and evaluating extent of disease in carcinoma of the uterine cervix.
Cervix Uteri ; Female ; Humans ; Hysterectomy ; Magnetic Resonance Imaging* ; Surgical Procedures, Operative ; Uterine Cervical Neoplasms* ; Uterine Neoplasms ; Vagina

A total of 20 patients(male : female=10:10, adult : children=8:12) with brainstem tumors had been received radiation therapy in the Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine between 1980 and 1990. Thirteen of 20 patients were treated with conventional radiation therapy (before 1989, 180~200 cGy per fraction, 5 days a week, total dose 4680~5400 cGy), and seven patients were treated with hypefractionated radiation therapy(in 1990, 100 cGy per fraction, twice daily 10 fractions a week, total dose 7200 cGy). Median follow up periods for conventional radiation therapy group and hyperfractionated radiation therapy group were 39 months and 10 months, respectively. Four of 20 Patients had histopathologic diagnosis prior to treatment ; 3 cases were low grade astrocytoma and 1 case was high grade astrocytoma. Overall 2-year actuarial survival rate was 30%. The prognosis of patients with a longer duration of symptom and sign was better(60% vs 12%), and the adult(52%) was better than children(14%). There was no significant difference between the focal(29%) and diffuse(20%) type. The initial clinical response was better in the hyperfractionated radiation therapy group. Because of the relatively small number of Patients and short follow up Period in hyPerFractionated radiation therapy group, there was no comparison between two group.
Adult ; Astrocytoma ; Brain Stem Neoplasms* ; Brain Stem* ; Diagnosis ; Follow-Up Studies ; Humans ; Prognosis ; Radiation Oncology ; Survival Rate

Fourty nine patients with squamous cell carcinoma of oral tongue were reviewed retrospectively for the evaluation of clinical manifestation and for the comparison between therapeutic modalites. The gross shape of the tumor was infiltrative in 22, ulcerative in 12, and ulceroinfiltrative type in 10 patients. Direct extension of the tumor was most commonly to the floor of the mouth. The incidence of nodal metastasis generally increased with tumor stage. 55% of the patients showed neck nodal metastasis at the time of diagnosis. Ipsilateral subdigastric node were most commonly involved, followed by submandibular nodes. The 5-year survival rate of patients treated with surgery and radiotherapy was 58.7% in contrast to 21.6% in radiation alone group. Overall 5-year survival rate was 31%. In radiation alone group, half of the patients in stage I, II were locally controlled. But the local control in stage III, IV was much inferior to early lesions. Especially, of 4 patients combined with implantation tecnhnique, 3 were completely controlled. 5-year survival rate of these implanted patients was 50%, 49.4% of patients treated over 7,000 cGy survived 5 years. This was significant in contrast to 6.4% of the group treated below 7,000 cGy. The most common sites of failures were primary sites. In early lesions primary radiotherapy with implantation would be an appropriate treatment in cancer of oral tongue, operation reserved for radiation failure. Operation and adjuvant radiotherapy is recommended in cases of advanced disease.
Carcinoma, Squamous Cell* ; Diagnosis ; Humans ; Incidence ; Mouth ; Neck ; Neoplasm Metastasis ; Radiotherapy ; Radiotherapy, Adjuvant ; Retrospective Studies ; Survival Rate ; Tongue* ; Ulcer

From March 1970 to December 1984, 21 patients treated initially with curative surgery for adenocarcinoma of the colon, referred to the Department of Radiation Oncology, College of Medicine, Yonsei University, were analyzed retrospectively. Thirteen of 21 patients who were considered to be ah high risk group (i.e, mainly stage B2 or above), received adjuvant postoperative radiation therapy. However, 2 of 13 patients did not complete their courses of radiotherapy as planned because of poor tolerance to radiotherapy or patient's refusal and were excluded from this study. Remaining 8 of 21 patients who did not received postoperative radiotherapy, presented with recurrence at the time of referral and treated with palliative radiotherapy. In 11 patients with postoperative radiotherapy, overall local failure rate was 9% (1/11) and the 5 year acturial survival rate was 55%. Local failure rates by stage were 0(0/4), 14%(1/7) for stage B2+B3, C1+C2+C3 respectively and 0(0/2), 17%(1/6), 0(0/3) for stage C1, B2+C2, B3+C3 respectively.
Adenocarcinoma* ; Colon* ; Disulfiram ; Humans ; Radiation Oncology ; Radiotherapy ; Recurrence ; Referral and Consultation ; Retrospective Studies ; Survival Rate

This study is the retrospective evaluation of ninety-six patients with biopsy-proven carcinoma of nasopharynx treated with radiotherapy at Yonsei University, College of Medicine, radiation Oncology from January 1971 to December 1985. Patient's age ranged from 15 to 71 years with a median age of 49 years. Fifty-two point five percent of local control and 47.5% of actuarial 5 year survival were achieved with radical radiotherapy. Five year survival rate for Stage I & II, III and IV were 75.0%, 74.6% and 41.4%, respectively. Distant metastasis rate was related with N stage (N1 12.5%, N1 0%, N2 23.5%, N3 32.1%) and histologic type (lymphoepithelioma 41.7%, squamous cell carcinoma 6.5%) but not with T stage. Thirty-one of sixty-seven patient covered adequate radiation field received induction chemotherapy. However induction chemotherapy dose not appear to improve over all survival.
Carcinoma, Squamous Cell ; Humans ; Induction Chemotherapy ; Nasopharynx ; Neoplasm Metastasis ; Radiation Oncology ; Radiotherapy* ; Retrospective Studies ; Survival Rate

The treatment planning and dosimetry of small fields for stereotactic radiosurgery with 10 MV x-ray isocentrically mounted linear accelerator is presented. Special consideration in this study was given to the variation of absorbed dose with field size, the central axis percent depth doses and the combined moving beam dose distributon. The collimator scatter correction factors of small fields (1x1~3x3 cm2) were measured with ion chamber at a target chamber distance of 300cm where the projected fields were larger than the polystyrene buildup caps and it was calibrated with the tissue equivalent solid state detectors of small size (TLD, PLD, ESR and semiconductors). The central axis percent depth doses for 1x1 and 3x3 cm2 fields could be derived with the same acuracy by interpolating between measured values for larger fields and calcu1ated zero area data, and it was also calibrated with semiconductor detectors. The agreement between experimental and calculated data was found to be under +/-2% within the fields. The three dimensional dose planning of stereotactic focusing irradiation on small size tumor regions was performed with dose planning computer system (Therac 2300) and was verified with film dosimetry. The more the number of strips and the wider the angle of arc rotation, the larger were the dose delivered on tumor and the less the dose to surrounding the normal tissues. The circular cone, we designed, improves the alignment, minimizes the penumbra of the beam and formats ball shape of treatment area without stellate patterns. These dosimetric techniques can provide adequate physics background for stereotactic radiosurgery with small radiation fields and 10 MV x-ray beam.
Axis, Cervical Vertebra ; Computer Systems ; Film Dosimetry ; Particle Accelerators ; Polystyrenes ; Radiosurgery* ; Semiconductors