• Radiation Oncology Journal
• /
• v.20 no.4
• /
• pp.391-395
• /
• 2002

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 co 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 ${\pm}3\%$. Therefore, further efforts such ws modification in processing of the archived image through DICOM3.0 format are required to lessen the dose difference.

• Progress in Medical Physics
• /
• v.21 no.2
• /
• pp.218-222
• /
• 2010

As radiation is irradiated from various directions in intensity modulated radiation therapy (IMRT), longer treatment time than conventional treatment method is taken. In case of the patients who have problem to keep same posture for long time because of pain and injury, reducing treatment time through increased dose rate is a way for effective treatment. This study measured and found out the variation of dose and dose distribution in accordance with dose rate variation. IMRT treatment plan was set up to investigate from 5 directions - $0^{\circ}$, $72^{\circ}$, $144^{\circ}$, $216^{\circ}$, $288^{\circ}$ - using ECLIPSE system (Varian, SomaVision 6.5, USA). To confirm dose and dose rate in accordance with dose rate variation, dose rate was set up as 100, 300, 500 MU/min, and dose and dose distribution were measured using ionization chamber (PTW, TN31014) and film dosimeter (EDR2, Kodak). At this time, film dosimeter was inserted into acrylic phantom, then installed to run parallel with beam's irradiating direction, 21EX-S (Varian, USA) was utilized as linear accelerator for irradiation. The measured film dosimeter was analyzed using VXR-16 (Vidar System Corporation) to confirm dose distribution.

• Radiation Oncology Journal
• /
• v.3 no.2
• /
• pp.123-129
• /
• 1985

A retrospective analysis was undertaken of 46 patients who were referred with squamous cell carcinoma of the esophagus during the period of March 1979 through October 1982, and who were treated by curative radiotherapy in the Department of Therapeutic Radiology Seoul National University Hospital. The overall two-year actuarial survival rate was $20\%$ Survival was analyzed with respect to the site of the cancer, its size, radiation dose, and degree of response. Patients with the best two-year survival rate are the ones who had the tumor no of more than 5cm in length $(39.3\%)$ or confined to the upper third of the esophagus $(29.5\%)$. An optimum radiation dose ranged from 1600 to 1700 rets. Patients to complete response had $42.4\%$ of two-year actuarial survival, but those to no response had $0\%$ of survival.

• Korean Journal of Head & Neck Oncology
• /
• v.16 no.2
• /
• pp.172-176
• /
• 2000

Objectives: To improve local control and reduce toxicity, 3-D conformal radiotherapy was used as a boost the primary tumor site following fractionated radiotherapy in patients with nasopharyngeal carcinoma. Materials and Methods: Eight patients with previously untreated nasopharyngeal carcinomas were treated with 3-D conformal radiotherapy following fractionated radiotherapy from September 1998 to April 2000. All patients had biopsy confirmation of disease before radiation therapy. Stages were II in 1, III in 5, and IV in 2. Two patients received cisplatin based chemotherapy in addition to radiation therapy; induction chemotherapy in 1, concurrent chemoradiation in 1. 3-D conformal radiotherapy delivered using 6MV Linac as a boost(range 25.2-28.8Gy, median 25.7Gy) following conventionally fractionated radiotherapy(range 50.4Gy). Average total dose ranged from 75.6-79.2Gy(median 76Gy). Follow-up time was 4-21 months(median 9.6 months). Results: Seven of 8 patients were evaluated radiologically within 3 months after completion of radiation therapy. All 7 patients were seen complete remission. One of 7 patients had distant metastasis after 5 months and local failure after 7 months. The tree interval of local recurrence was ranged from 4 - 21 months(median 10.2 months). One patient without radiological evaluation got complete remission clinically. Treatment related toxicity was grade 1-3 xerostomia, dysphagia, and mucositis. During 3-D conformal radiotherapy, there was no aggravation of any toxicity. Conclusion: Although the number of patients was small and follow-up period was short, 3-D conformal radiotherapy following conventional radiotherapy improved tumor control and dose escalation without increased toxicity. Survival and late toxicity should be evaluated through long term follow-up. In addition, it is necessary to confirm the benefits of 3-D conformal radiotherapy in nasopharyngeal carcinoma with randomized trial.

• Radiation Oncology Journal
• /
• v.34 no.2
• /
• pp.81-87
• /
• 2016

Hypofractionated whole breast irradiation (HF-WBI) has been proved effective and safe and even better for late or acute radiation toxicity for early breast cancer. Moreover, it improves patient convenience, quality of life and is expected to be advantageous in the medical care system by reducing overall cost. In this review, we examined key randomized trials of HF-WBI, focusing on adequate patient selection as suggested by the American Society of Therapeutic Radiology and Oncology (ASTRO) guideline and the radiobiologic aspects of HF-WBI in relation to its adoption into clinical settings. Further investigation to identify the current practice pattern or cost effectiveness is warranted under the national health insurance service system in Korea.

• Radiation Oncology Journal
• /
• v.5 no.2
• /
• pp.165-168
• /
• 1987

The generalized Bathe method, proposed by Webb and Fox, which is a method of calculation of dose correction factor for the purpose of heterogeneous tissue, is complex even for a few kind of tissues. The method was modified for the purpose of getting a simple method that divide the multilayer of heterogeneous tissues into some groups of adjacent-tissue pairs. This new method could reduce the number of exponential terms and the time for calculating the dose correction factors by manual and computer calculation.

• Korean Journal of Head & Neck Oncology
• /
• v.17 no.1
• /
• pp.59-62
• /
• 2001

Objectives: We report an interim result of conformal radiotherapy in a patient with early stage cancer at the base of the tongue, which developed in a previously irradiated area. Materials and Methods: A 64-year-old male patient was diagnosed with T4N0M0 supraglottic cancer. He received 72Gy of radiation therapy from 21 November 1988 to 24 February 1989. He had local failure and underwent a salvage total laryngectomy on 28 August 1989. Subsequently, he did well. In early 1999, he suffered from throat pain. He had a 2.5cm ulcerative mass at the base of his tongue, in the area that had been irradiated previously. Biopsy showed squamous cell carcinoma. After workup, he was diagnosed with base of tongue cancer with T2N0M0. Surgery was not feasible because the morbidity was not acceptable. Since it was difficult to re-irradiate the area with a curable dose using conventional 2D radiation therapy with an acceptable morbidity, we decided to try conformal radiotherapy. We used 7 static beam ports with field sizes from $7x6.4\;to\;8x8cm^2$, using 6 and 10MV photons. The fractionation regimen was 1.8Gy, 5 times per week. He received 64.8Gy in 36 fractions from 9 April 1999 to 1 June 1999. Results: In the 21 months since radiotherapy, the patient has not experienced any acute or chronic complications, such as xerostomia. He experienced relief of pain shortly after the start of radiotherapy, showed a complete response, and is still doing well. Conclusion: Conformal radiotherapy can be used to treat cancer that develops within a previously irradiated field, with curative intent.

• Radiation Oncology Journal
• /
• v.7 no.2
• /
• pp.205-211
• /
• 1989

From July 1984 to September 1988, 27 patients with limited stage small cell lung cancer were treated with combined modality (combination chemotherapy Plus radiotherapy) at the Department of Therapeutic Radiology in Kyungpook National University Hospital. Of the 27 patients, 19$(70\%)$ achieved a complete response, 6$(22\%)$ a partial response, and 2$(8\%)$ no response. Female, performance status HO, serum enolase level below 30ng/ml, radiation dose over 4500 cGy, and 4 or more cycles of chemotherapy had a favorable effect on the rates of complete response, although there were no statistical differences according to the variables. Median survival time was 10 months and overall 1- and 2-year survival rates were $40,7\%$ and $12.2\%$, respectively. Complete response (p<0.05), performance status HO (p<0.05), 4 or more cycles of chemotherapy (p<0.05), and radiation dose over 4500 cGy had a significantly favorable effect on 2-year survival rate. Prophylactic cranial irradiation or sex had no effect on survival. The results of this study suggest that radiation treatment should be combined with combination chemotherapy in the therapeutic strategy of SCLC of limited stage.

• Journal of the Korean Society of Radiology
• /
• v.10 no.6
• /
• pp.469-476
• /
• 2016

In this study, evaluated absorbed dose of moving target using PLD according to prescribed dose and therapeutic technique. First, result of MCNPX when target was deviated from exposure field was reduced dose in proportion to distance. According to prescribed dose, absorbed dose of 3D CRT was better than IMRT in low dose and IMRT was more better in high dose. Absorbed dose of 3D CRT was highest according to therapeutic technique. Therefore, 3D CRT was technique of irradiated highest dose to moving target. But, considered protective effect of normal tissue and patient condition that therapeutic technique was selected to maximized treatment efficiency.

• Korean Journal of Head & Neck Oncology
• /
• v.15 no.2
• /
• pp.162-165
• /
• 1999

Background and Objectives: Multiple primary tumors of the upper aerodigestive tract are not unusual. We examined head and neck cancer patients to discover the presence of second primary cancer in their upper gastrointestinal tract, using esophagogastroscopy. Materials and Methods: Endoscopic examination of the upper gastrointestinal tract was performed on 51 patients whose head and neck cancers were treated at department of therapeutic radiology from August 1996 to April 1999. Two of all patients had been studied by barium swallowing study. In 51 patients, twenty-four had a primary tumor in the larynx, 8 in the oropharynx, 6 in the nasopharynx, 6 in the oral cavity, 6 in the hypopharynx, and 1 in the nasal cavity. Endoscopically pathologic lesions were biopsied. In control group, endoscopy was performed on 1097 patients who didn't complain any symptoms. Results: Endoscopy showed early malignant lesions in 4 cases(7.7%). Histology of esophageal cancers showed squamous cell carcinoma. Malignant lesions of stomach in 2 cases were histologically identified as adenocarcinoma. Two esophageal cancers occurred in patients whose primary lesions had oropharynx and hypopharynx. Two cases of gastric cancer were also accompanied by oropharynx and hypopharynx. The incidence of second primary cancer was 2 in oropharynx and 2 in hypopharynx. In all cases, second primary cancers were found simultaneously. In control group, 9(0.8%) of 1097 patients were confirmed as early esophageal and gastric cancers. Conclusion: The majority of esophageal and gastric cancer detected by endoscopy were early stage in both head and neck cancer and control group. The incidence of esophageal and gastric cancer of head and neck cancer patients was 10 times as high as that of control group. Although followup period was short, all second primary cancers were detected simultaneously. We would recommend that endoscopic evaluation be included in the workup and followup of all patients with newly diagnosed head and neck cancer.