PURPOSE: We have previously reported that human glioblastoma cells are sensitized to radiation-induced death after their exposure to trichostatin A (TSA), a histone deacetylase inhibitor (HDAC-I), prior to the irradiation. We aimed to measure the magnitude of the radiosensitizing effect of TSA in human head and neck cancer cell lines. MATERIALS AND MEHTODS: Human head and neck cancer cell lines, HN-3 and HN-9, were exposed to 0, 50, 100, and 200 nM TSA for 18 hr prior to irradiation. Then, the TSA-treated cells were irradiated with 0, 2, 4, 6, and 8 Gy, and cell survival was measured by clonogenic assay. RESULTS: Pre-irradiation exposure to TSA was found to radiosensitize HN-3 and HN-9 cell lines. In HN-9 cells, the fraction surviving after 2 Gy (SF2) was significantly reduced by treatment of TSA at concentration as low as 50 nM. However, a treatment with 200 nM TSA was required to significantly decrease SF2 in the HN-3 cell line. SER of pre-irradiation treatment with 200 nM TSA was 1.84 in HN-3 and 7.24 in HN-9, respectively. CONCLUSIONS: Our results clearly showed that human head and neck cancer cell lines can be sensitized to ionizing radiation by pre-irradiation inhibition of histone deacetylase (HDAC) using TSA, and that this potentiation might well be a general phenomenon.
Cell Line* ; Cell Survival ; Glioblastoma ; Head and Neck Neoplasms* ; Head* ; Histone Deacetylase Inhibitors* ; Histone Deacetylases* ; Histones* ; Humans* ; Radiation, Ionizing* ; Radiation-Sensitizing Agents

To evaluate the effectiveness of whole brain radiotherapy followed by stereotactic radiotherapy for newly diagnosed brain metastasis. MATERIALS AND METHODS: Thirty-three metastatic brain tumors received radiotherapy to the whole brain and stereotactic radiotherapy in 25 patients. Lung carcinomas were the most common (17/25) primary tumor. The radiation dose was 30 to 40 Gy for the whole brain, with a 12 to 40 Gy boost to the metastatic foci. Survival and local control rates were determined, and the prognostic factors for survival were evaluated. RESULTS: The overall median survival was 15 months and the actuarial survivals at 1- and 2-year were 67% and 31%, respectively. The local tumor control rate was 79%, with a median follow-up period of 9 months (2~36 months). The prognostic factors associated with survival were age, tumor size and the existence of active extracranial metastasis, with the performance status showing marginal significance. No acute or chronic complications were observed in the patients. CONCLUSION: From our data, cranial radiotherapy followed by stereotactic radiotherapy was useful in the local control of metastatic tumors, and in the survival of patients with tumor factors, such as small size or the absence of extracranial tumor activity, and host factors, such as young age or good performance status.
Brain Neoplasms ; Brain* ; Follow-Up Studies ; Humans ; Lung ; Neoplasm Metastasis* ; Radiotherapy* ; Treatment Outcome*

PURPOSE: For the purpose of quality assurance of self-developed stereotactic radiosurgery system, a multi-purpose phantom was fabricated, and accuracy of radiation dose distribution during radiosurgery was measured using this phantom. MATERIALS AND METHODS: A farmer chamber, a 0.125 cc ion chamber and a diode detector were used for the dosimetry. Six MV x-ray from a linear accelerator (CL2100C, Varian) with stereotactic radiosurgery technique (Green Knife) was used, and multi-purpose phantom was attached to a stereotactic frame (Fisher type). Dosimetry was done by combinations of locations of the detectors in the phantom, fixed or arc beams, gantry angles (20 ~100 ), and size of the circular tertiary collimators (inner diameters of 10 degrees~40 degrees mm). RESULTS: The measurement error was less than 0.5% by Farmer chamber, 0.5% for 0.125 cc ion chamber, and less than 2% for diode detector for the fixed beam, single arc beam, and 5-arc beam setup. CONCLUSION: We confirmed the accuracy of dose distribution with the radiosurgery system developed in our institute and the data from this study would be able to be effectively used for the improvement of quality assurance of stereotactic radiosurgery or fractionated stereotactic radiotherapy system.
Particle Accelerators ; Radiosurgery* ; Radiotherapy

PURPOSE: To confirm the accuracy of the radiation dose at the isocenter by the standard linear accelerator-based stereotactic radiosurgery technique which was developed at Seoul National University Hospital. MATERIALS AND METHODS: Radiation dosimetry was undertaken during standard 5-arc radiosurgery using 6 MV X-ray beam from CL2100C linac. The treatment head was attached with circular tertiary collimators of 10 and 20 mm diameter. We measured the absorbed dose at the isocenter of a multi-purpose phantom using two kinds of detector : a 0.125 cc ionization chamber and a silicon diode detector. RESULTS: The dose differences at each arc plane between the planned dose and the measured dose at the isocenter raged from -0.73% to -2.69% with the 0.125 cc ion chamber, and from -1.29% to -2.91% with the diode detector during radiosurgery with the tertiary collimator of 20 mm diameter. Those with the 10-mm tertiary collimator ranged from -2.39% to -4.25% with the diode. CONCLUSION: The dose accuracy at the isocenter was +/-3%. Therefore, further efforts such as modification in processing of the archived image through DICOM3.0 format are required to lessen the dose difference.
Head ; Radiometry ; Radiosurgery* ; Rage ; Seoul* ; Silicon

No abstract available.
Germinoma* ; Radiotherapy*

PURPOSE: Total body irradiation (TBI) or whole body irradiation is used to acquire immune suppression, to treat malignant lymphoma and leukemia, and as an conditioning regimen for bone marrow transplantation. For these purposes, many methods were developed to obtain homogenous dose distribution. The objective of this study was to analyze and confirm the accuracy and the homogeneity of the treatment setup, the parallel opposed lateral technique, currently used in Seoul National University Hospital. MATERIALS AND METHODS: Surface dose data, measured with a thermoluminescent dosimeter, of 8 patients among 10 patients, who were given total body irradiation with the parallel opposed lateral technique between September 1996 to August 1998, at Seoul National University Hospital were analyzed. Surface doses were measured at the head, neck, axilla, thigh, and ankle level. Surface and midline doses were measured with similar set-up and technique in the Humanoid phantom. RESULTS: Measured surface doses relative to prescribed dose for the head, neck, axilla, thigh, and ankle level were 91.3+/-7.8, 98.3+/-7.5, 95.1+/-6.3, 98.3+/-5.5, and 95.3+/-6.3%, respectively. The midline doses of the head, neck, axilla, thigh, and ankle level estimated from the surface-to-midline ratios in the Humanoid phantom were 103.4+/-9.0, 107.8+/-10.5, 91.1+/-6.1, 93.8+/-4.5, and 104.5+/-9.3%, respectively. Measured surface doses and estimated midline doses ranged from -8.9% to + 7.8%. Midline doses at the neck and the axilla level deviated more than 5% from the prescribed doses. The difference of the estimated midline doses at the neck and the axilla level and the actual doses were attributed to the thickness differences between the Humanoid phantom and the patients. CONCLUSION: Distribution of the midline doses as well as the surface doses were measured to be within -8.7 - +7.8% range. Actual dose distribution in the patient is expected to be better than the measured dose range mainly attributed to thickness difference between the patient and the Humanoid phantom.
Ankle ; Axilla ; Bone Marrow Transplantation ; Head ; Humans ; Leukemia ; Lymphoma ; Neck ; Seoul ; Thigh ; Whole-Body Irradiation*

No astract is available
Radiosurgery*

PURPOSE: This study was to obtain the basic dosimetric data using the 10 MV X-ray for the total body irradiation. MATERIALS AND METHODS: A linear accelerator photon beam is planned to be used as a radiation source for total body irradiation (TBI) in Chonnam University Hospital. The planned distance from the target to the midplane of a patient is 360cm and the maximum geometric field size is 144cm' 144cm. Polystyrene phantom sized 30 30 30.2cm3 and consisted of several sheets with various thickness, and a parallel plate ionization chamber were used to measure surface dose and percent depth dose (PDD) at 345cm SSD, and dose profiles. To evaluate whether a beam modifier is necessary for TBI, dosimetry in build up region was made first with no modifier and next with an 1cm thick acryl plate 20cm far from the polystyrene phantom surface. For a fixed source-chamber distance, output factors were measured for various depth. RESULTS: As any beam modifier was not on the way of radiation of 10MV X-ray the dmax and surface dose was 1.8cm and 61%, respectively, for 345cm SSD. When an 1cm thick acryl plate was put 20cm far from polystyrene phantom for the SSD, the dmax and surface dose were 0.8cm and 94%, respectively. With acryl as a beam spoiler, the PDD at 10cm depth was 78.4% and exit dose was a little higher than expected dose at interface of exit surface. For two-opposing fields for a 30cm phantom thick phantom, the surface dose and maximum dose relative to mid-depth dose in our experiments were 102.5% and 106.3%, respectively. The off-axis distance of that point of 95% of beam axis dose were 70cm on principal axis and 80cm on diagonal axis. CONCLUSION: 1. To increase surface dose for TBI by 10MV X-ray at 360cm SAD, 1cm thick acrylic spoiler was sufficient when distance from phantom surface to spoiler was 20 cm. 2. At 345cm SSD, 10MV X-ray beam of full field produced a satisfiable dose uniformity for TBI within 7% in the phantom of 30cm thickness by two-opposing irradiation technique. 3. The uniform dose distribution region was 67cm on principal axis of the bean and 80cm on diagonal axis from beam axis. 4. The output factors at mid-point of various thickness revealed linear relation with depth, and it could be applicable to practical TBI.
Axis, Cervical Vertebra ; Humans ; Jeollanam-do ; Particle Accelerators* ; Polystyrenes ; Silver Sulfadiazine ; Whole-Body Irradiation*

PURPOSE: To investigate the levels of radiation exposure of an operator which may be influenced by the wearing an apron, type of procedure, duration of fluoroscopy and operator's skill during various interventional procedures MATERIALS AND METHODS: Radiation doses were measured both inside and outside the apron(0.5mm lead equivalent) of the operator by a film badge monitoring method and the duration of fluoroscopy was measured in 96 procedures prospectively. The procedures were 30 transcatheter arterial embolizations (TAE), 25 percutaneous transhepatic biliary drainages (PTBD), 16 stone removals (SR), 15 percutaneous needle aspirations (PCNA) and 10 percutaneous nephrostomies(PCN). To assess the difference of exposure by the operator's skill, the procedures of TAE and PTBD were done separately by groups of staffs and residents. RESULTS: Average protective effect of the apron was 72.8%. Average radiation exposure(unit:micro Sv/procedure) was 23.3 in PTBD by residents, 10.0 in PTBD by staffs, 10.0 in SR, 8.7 in TAE by residents, 7.3 in TAE by staffs, 9.0 in PCN and 6.0 in PCNA. Average radiation exposure of residents were 1.9 times greater than those of staffs. CONCLUSION: Radiation exposure was not proportionally related to the duration of fiuoroscopy, but influenced by wearing an apron, various types o[procedure and operator's skills.
Aspirations (Psychology) ; Film Dosimetry ; Fluoroscopy ; Needles ; Pregnenolone Carbonitrile ; Proliferating Cell Nuclear Antigen ; Prospective Studies

An important problem in radiosurgery is the utilization of the proper beam parameters, to which dose shape is sensitive. Streotactic radiosurgery techniques for a linear accelerator typically, use circular radiation fields with multiple arcs to produce an spherical radiation distribution. Target volumes are irregular in shape for a certain case, and spherical distributions can irradiate normal tissues to high dose as well as the target region. The current improvement to dose distribution utilizes treating multiple isocenters or weighting various arcs to change treatment volume shape. In this paper another premising study relies upon dynamically shaping the treatment beam to fit the beam's eye view of the target. This conformal irradiation technique was evaluated by means of visual three dimensional dose distribution, dose volume histograms to the target volume and surrounding normal brain. It is shown that using even less arcs than multiple isocenter irradiation technique, the conformal therapy yields comparable dose gradients and superior homogeneity of dose within the target volume.
Brain ; Particle Accelerators ; Radiosurgery*