Biomedical subjects

Byong Yong Yi

Publications and source records attributed to Byong Yong Yi.

8 recordsLinked to original sources

PubMed2006

Preliminary results of a phase I/II study of simultaneous modulated accelerated radiotherapy for nondisseminated nasopharyngeal carcinoma.

PURPOSE: To present preliminary results of intensity-modulated radiotherapy (IMRT) with the simultaneous modulated accelerated radiotherapy (SMART) boost technique in patients with nasopharyngeal carcinoma (NPC). METHODS AND MATERIALS: Twenty patients who underwent IMRT for nondisseminated NPC at the Asan Medical Center between September 2001 and December 2003 were prospectively evaluated. Intensity-modulated radiotherapy was delivered with the "step and shoot" SMART technique at prescribed doses of 72 Gy (2.4 Gy/day) to the gross tumor volume, 60 Gy (2 Gy/day) to the clinical target volume and metastatic nodal station, and 46 Gy (2 Gy/day) to the clinically negative neck region. Eighteen patients also received cisplatin once per week. RESULTS: The median follow-up period was 27 months. Nineteen patients completed the treatment without interruption; the remaining patient interrupted treatment for 2 weeks owing to severe pharyngitis and malnutrition. Five patients (25%) had Radiation Therapy Oncology Group Grade 3 mucositis, whereas 9 (45%) had Grade 3 pharyngitis. Seven patients (35%) lost more than 10% of their pretreatment weight, whereas 11 (55%) required intravenous fluids and/or tube feeding. There was no Grade 3 or 4 xerostomia. All patients showed complete response. Two patients had distant metastases and locoregional recurrence, respectively. CONCLUSION: Intensity-modulated radiotherapy with the SMART boost technique allows parotid sparing, as shown clinically and by dosimetry, and might also be more effective biologically. A larger population of patients and a longer follow-up period are needed to evaluate ultimate tumor control and late toxicity.

Adult↗

PubMed2006

Clinical results of stereotactic body frame based fractionated radiation therapy for primary or metastatic thoracic tumors.

The aim of this study was to evaluate the treatment outcomes of stereotactic body radiation therapy for treating primary or metastatic thoracic tumors using a stereotactic body frame. Between January 1998 and February 2004, 101 lesions from 91 patients with thoracic tumors were prospectively reviewed. A dose of 10-12 Gy per fraction was given three to four times over consecutive days to a total dose of 30-48 Gy (median 40 Gy). The overall response rate was 82%, with 20 (22%) complete responses and 55 (60%) partial responses. The one- and two-year local progression free survival rates were 90% and 81%, respectively. The patients who received 48 Gy showed a better local tumor control than those who received less than 48 Gy (Fisher exact test; p = 0.004). No pulmonary complications greater than a RTOG toxicity criteria grade 2 were observed. The experience of stereotactic body frame based radiation therapy appears to be a safe and promising treatment modality for the local management of primary or metastatic lung tumors. The optimal total dose, fractionation schedule and treatment volume need to be determined after a further follow-up of these results.

Adolescent↗

PubMed2005

Phase II study of radiotherapy with three-dimensional conformal boost concurrent with paclitaxel and cisplatin for Stage IIIB non-small-cell lung cancer.

PURPOSE: To evaluate the efficacy and toxicity of concurrent chemoradiotherapy with paclitaxel/cisplatin for Stage IIIB locally advanced non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS: Radiotherapy was administered to a total dose of 70.2 Gy (daily fraction of 1.8 Gy, 5 days/wk), over an 8-week period, combined with chemotherapy. The chemotherapy consisted of weekly 40 mg/m2 of paclitaxel plus 20 mg/m2 of cisplatin for 8 consecutive weeks. All patients received three-dimensional conformal radiotherapy (3D-CRT), based on computed tomography simulated planning after 41.4 Gy. The median follow-up period of survivors was 24 months. RESULTS: Between January 2000 and October 2002, 135 patients with a median age of 60 years were enrolled and analyzed in this prospective trial. The overall response rate was 75% including 2 cases of complete response. The major patterns of failure were local failure and distant metastasis. The 2-year overall and progression-free survival rates were 37% and 18%, respectively. The median overall and progression-free survival times were 17 months and 9 months, respectively. Hematologic toxicity >Grade 2 was observed in 19% of patients and severe non-hematologic toxicity was infrequent. CONCLUSIONS: Three-dimensional conformal radiotherapy, combined with paclitaxel and cisplatin chemotherapy, was associated with a satisfactory outcome with manageable toxicity. Further investigations are needed to improve the local control.

Adenocarcinoma↗

PubMed2005

Early evaluation of the response to radiotherapy of patients with squamous cell carcinoma of the head and neck using 18FDG-PET.

The aim was to evaluate the efficacy of positron emission tomography (PET) with 2-[F-18]fluoro-2-deoxy-d-glucose (FDG) in early discrimination of response to definitive radiotherapy (RT) in patients with squamous cell carcinoma of the head and neck (SCCHN). Twenty-four patients who underwent FDG-PET scans before and after radiotherapy for nondisseminated SCCHN at the Asan Medical Center between August 2001 and September 2002 were prospectively evaluated. Initial FDG-PET scans were performed within 1 month before RT, and follow-up FDG-PET scans were performed 1 month after completion of RT. FDG-PET images were analyzed by standard uptake value (SUV). All patients were followed for more than 6 months. Pretreatment SUV ranged from 3.4 to 14.0 (median, 6.0), while posttreatment SUV ranged from ground level to 7.7 (median, 2.0). In evaluating residual tumors in these SCCHN patients, the overall sensitivity of FDG-PET was 100%, while its overall specificity was 87%. FDG-PET is effective in evaluating the response to radiation in patients with SCCHN. Timing the follow-up FDG-PET scan 1 month after completion of RT was not too rapid for evaluating the response to radiation.

Adolescent↗

PubMed2005

Immobilization effect of air-injected blanket (AIB) for abdomen fixation.

A new device for reducing the amplitude of breathing motion by pressing a patient's abdomen using an air-injected blanket (AIB) for external beam radiation treatments has been designed and tested. The blanket has two layers sealed in all four sides similar to an empty pillow made of urethane. The blanket is spread over the patient's abdomen with both ends of the blanket fixed to the sides of the treatment couch or a baseboard. The inner side, or patient side, of the blanket is thinner and expands more than the outer side. When inflated, the blanket balloons and effectively puts an even pressure on the patient's abdomen. Fluoroscopic observation was performed to verify the usefulness of AIB for patients with lung, breast cancer, or abdominal cancers. Internal organ movement due to breathing was monitored and measured with and without AIB. With the help of AIB, the average range of diaphragm motion was reduced from 2.6 to 0.7 cm in the anterior-to-posterior direction and from 2.7 to 1.3 cm in the superior-to-inferior direction. The motion range in the right-to-left direction was negligible, for it was less than 0.5 cm. These initial testing demonstrated that AIB is useful for reducing patients' breathing motion in the thoracic and abdominal regions comfortably and consistently.

Abdomen↗

PubMed2003

Phase II study of three-dimensional conformal radiotherapy and concurrent mitomycin-C, vinblastine, and cisplatin chemotherapy for Stage III locally advanced, unresectable, non-small-cell lung cancer.

PURPOSE: To evaluate the feasibility, treatment outcome, and toxicity of hyperfractionated three-dimensional conformal radiotherapy (CRT) and concurrent mitomycin-C, vinblastine, and cisplatin (MVP) chemotherapy in locally advanced, unresectable, Stage III non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS: Between August 1993 and December 1996, 161 patients with unresectable Stage III NSCLC were entered into this trial, and 146 (91%) completed the treatment. Hyperfractionated RT was given to a total dose of 64.8-70 Gy (1.2 Gy/fraction, b.i.d.) with two cycles of concurrent MVP chemotherapy (mitomycin-C 6 mg/m(2) on Days 2 and 29, vinblastine 6 mg/m(2) on Days 2 and 29, and cisplatin 60 mg/m(2) on Days 1 and 28). Of the 146 patients who completed the treatment, 78 received noncoplanar three-dimensional CRT using 4-6 fields and 17 received coplanar-segmented CRT. The clinical tumor response was assessed 1 month after RT completion by CT. Toxicity was graded using the Southwestern Oncology Group criteria. The normal tissue complication probability for the lung was calculated to determine the correlation with radiation pneumonitis, if any. Nineteen (13%) had Stage IIIA and 127 (87%) had IIIB disease, including 16 patients with pleural effusion and 20 with supraclavicular lymph node metastasis. RESULTS: The response rate was 75%, composed of 22% complete responders and 53% partial responders. With a minimal follow-up of 45 months, the overall survival rate was 51.2% at 1 year, 25.1% at 2 years, and 14.8% at 5 years; the median survival was 12 months. Patients achieving a complete response (n = 32) had a 2-year overall survival rate of 49.8% and a 5-year survival rate of 39.2% compared with 22.5% and 11.4%, respectively, for the partial responders (n = 78; p = 0.0001). The actuarial local progression-free survival rate for all patients was 65.4% at 1 year, 42.1% at 2 years, and 36.3% at 4 years, and the actuarial distant-free survival rate was 65.4% at 1 year, 42.1% at 2 years, and 36.2% at 5 years. Severe weight loss (>10%) occurred in 20 (13.7%) of the 146 patients during treatment, 42 patients (29%) developed radiation pneumonitis (29 Grade 1 and 13 Grade 2). The average normal tissue complication probability value of the patients who had radiation pneumonitis was significantly greater than that of patients without pneumonitis (66.0% vs. 26.4%). Four patients died of treatment-related toxicity. CONCLUSION: Hyperfractionated three-dimensional CRT and concurrent chemotherapy, as described here, is a well-tolerated regimen with acceptable toxicity. More effective treatment schemes are required to improve local disease control and overall survival.

Adult↗

PubMed2003

Stereotactic body frame based fractionated radiosurgery on consecutive days for primary or metastatic tumors in the lung.

To evaluate the feasibility and treatment outcomes of stereotactic radiosurgery (SRS) using a stereotactic body frame (Precision Therapy), we prospectively reviewed 34 tumors of the 28 patients with primary or metastatic intrathoracic lung tumors. Eligible patients included were nine with primary lung cancer and 19 with metastatic tumors from the lung, liver, and many other organs. A single dose of 10 Gy to the clinical target volume (CTV) was delivered to a total dose of 30-40 Gy with three to four fractions. Four to eight coplanar or non-coplanar static fields were generated to adequately cover the planning target volume (PTV) as well as to exclude the critical structures as much as possible. More than 90% of the PTV was delivered the prescribed dose in the majority of cases (average; 96%, range; 74-100%). The mean PTV was 41.4 cm(3) ranging from 4.4 to 230 cm(3). Set-up error was within 5 mm in all directions (X, Y, Z axis). The response was evaluated by using a chest CT and/or 18FDG-PET scans after SRS treatment, 11 patients (39%) showed complete response, 12 (43%) partial response (decrease of more than 50% of the tumor volume), and four patients showed minimally decreased tumor volume or stable disease, but one patient showed progression disease. With a median follow-up period of 18 months, a local disease progression free interval was ranging from 7 to 35 months. Although all patients developed grade one radiation pneumonitis within 3 months, none had symptomatic or serious late complications after completing SRS treatment. Given these observations, it is concluded that the stereotactic body frame based SRS is a safe and effective treatment modality for the local management of primary or metastatic lung tumors. However, the optimum total dose and fractionation schedule used should be determined after the longer follow-up of these results.

Adult↗

PubMedDate not supplied

Multiphasic perfusion computed tomography in hyperacute ischemic stroke: comparison with diffusion and perfusion magnetic resonance imaging.

PURPOSE: The purpose of this study was to compare multiphasic perfusion computed tomography (CT) with diffusion and perfusion magnetic resonance imaging (MRI) in predicting final infarct volume, infarct growth, and clinical severity in patients with hyperacute ischemia untreated by thrombolytic therapy. METHOD: Multiphasic perfusion CT was performed in 19 patients with ischemic stroke within 6 hours of symptom onset. Two CT maps of peak and total perfusion were generated from CT data. Diffusion-weighted imaging (DWI) and perfusion MRI were obtained within 150 minutes after CT. Lesion volumes on CT and MRI were compared with final infarct volume and clinical scores, and mismatch on CT or MRI was compared with infarct growth. RESULTS: The lesion volume on the CT total perfusion map strongly correlated with MRI relative cerebral blood volume (rCBV), and that on the CT peak perfusion map strongly correlated with MRI relative cerebral blood flow (rCBF) and rCBV (P < 0.001). The lesion volume on unenhanced CT or DWI moderately correlated with final infarct volume, but only lesion volume on unenhanced CT weakly correlated with baseline clinical scores (P = 0.024). The lesion volumes on the CT peak perfusion map and MRI rCBF similarly correlated with final infarct volume and clinical scores and more strongly than those on mean transit time (MTT) or time to peak (TTP). DWI-rCBF or CT mismatch was more predictive of infarct growth than DWI-MTT or DWI-TTP mismatch. CONCLUSION: Multiphasic perfusion CT is useful and of comparable utility to diffusion and perfusion MRI for predicting final infarct volume, infarct growth, and clinical severity in acute ischemic stroke.

Acute Disease↗