• Radiation Oncology Journal
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• v.34 no.1
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• pp.18-25
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• 2016

Purpose: Radiotherapy of the neck is known to cause carotid artery stenosis. We compared the carotid artery dose received between volumetric modulated arc therapy (VMAT) and conventional fixed-field intensity-modulated radiotherapy (IMRT) plans in patients with early glottic cancer. Materials and Methods: Twenty-one early glottic cancer patients who previously underwent definitive radiotherapy were selected for this study. For each patient, double arc VMAT, 8-field IMRT, 3-dimensional conformal radiotherapy (3DCRT), and lateral parallel-opposed photon field radiotherapy (LPRT) plans were created. The 3DCRT plan was generated using lateral parallel-opposed photon fields plus an anterior photon field. VMAT and IMRT treatment plan optimization was performed under standardized conditions to obtain adequate target volume coverage and spare the carotid artery. Dose-volume specifications for the VMAT, IMRT, 3DCRT, and LPRT plans were calculated with radiotherapy planning system. Monitor units (MUs) and delivery time were measured to evaluate treatment efficiency. Results: Target volume coverage and homogeneity results were comparable between VMAT and IMRT; however, VMAT was superior to IMRT for carotid artery dose sparing. The mean dose to the carotid arteries in double arc VMAT was reduced by 6.8% compared to fixed-field IMRT (p < 0.001). The MUs for VMAT and IMRT were not significantly different (p = 0.089). VMAT allowed an approximately two-fold reduction in treatment delivery time in comparison to IMRT (3 to 5 minutes vs. 5 to 10 minutes). Conclusion: VMAT resulted in a lower carotid artery dose compared to conventional fixed-field IMRT, and maintained good target coverage in patients with early glottic cancer.

• Radiation Oncology Journal
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• v.21 no.3
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• pp.245-249
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• 2003

A primary malignant melanoma of the vagina is a very rare gynecological malignant tumor. Its clinical behavior is more aggressive than that of cutaneous and vulvar melanomas. We present a case of a large sized primary melanoma of the lower third of the vagina, with a cervical lesion, in a 58-year-old postmenopausal woman. The patient was treated with conventional external radiation therapy and intracavitary radiotherapy (ICR), without surgical treatment. Although the primary lesion showed a partial response, the patient died of extensive metastases, which were found 4.5 months after the initial diagnosis. We suggest that shortening the treatment period, such as hypofractionated radiation therapy and surgical removal, and various systemic therapies for preventing early distant metastasis, are appropriate treatments for a primary malignant melanoma of the vagina, with a large tumor size.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.1
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• pp.1-5
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• 2007

Purpose: The accuracy and advantages of OBI(On Board Imager) against the conventional method like film and EPID for the setup error correction were evaluated with the analysis of the accumulated data which were produced in the process of setup error correction using OBI. Materials and Methods: The results of setup error correction using OBI system were analyzed for the 130 patients who had been planned for 3 dimensional conformal radiation therapy during March 2006 and May 2006. Two kilo voltage images acquired in the orthogonal direction were fused and compared with reference setup images. The setup errors in the direction of vertical, lateral, longitudinal axis were recorded and calculated the distance from the isocenter. The corrected setup error were analyzed according to the lesion and the degree of shift variations. Results: There was no setup error in the 41.5% of total analyzed patients and setup errors between 1mm and 5mm were found in the 52.3%. 6.1% patients showed the more than 5mm shift and this error were verified as a difference of setup position and the movement of patient in a treatment room. Conclusion: The setup error analysis using OBI in this study verified that the conventional setup process in accordance with the laser and field light was not enough to get rid of the setup error. The KV images acquired using OBI provided good image quality for comparing with simulation images and much lower patients' exposure dose compared with conventional method of using EPID. These advantages of OBI system which were confirmed in this study proved the accuracy and priority of OBI system in the process of IGRT(Image Guided Radiation Therapy).

• Progress in Medical Physics
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• v.34 no.4
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• pp.41-47
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• 2023

Purpose: This study aimed to dosimetrically compare the technique of three-dimensional conformal radiotherapy (3D CRT), which is a traditional prophylactic cranial irradiation method, and the intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques used in the last few decades with the dynamic conformal arc therapy (DCAT) technique. Methods: The 3D CRT, VMAT, IMRT, and DCAT plans were prepared with 25 Gy in 10 fractions in a Monaco planning system. The target volume and the critical organ doses were compared. A comparison of the body V₂, V₅, and V₁₀ doses, monitor unit (MU), and beam on-time values was also performed. Results: In planned target volume of the brain (PTV_Brain), the highest D99 dose value (P<0.001) and the most homogeneous (P=0.049) dose distribution according to the heterogeneity index were obtained using the VMAT technique. In contrast, the lowest values were obtained using the 3D CRT technique in the body V₂, V₅, and V₁₀ doses. The MU values were the lowest when DCAT (P=0.001) was used. These values were 0.34% (P=0.256) lower with the 3D CRT technique, 66% (P=0.001) lower with IMRT, and 72% (P=0.001) lower with VMAT. The beam on-time values were the lowest with the 3D CRT planning (P<0.001), 3.8% (P=0.008) lower than DCAT, 65% (P=0.001) lower than VMAT planning, and 76% (P=0.001) lower than IMRT planning. Conclusions: Without sacrificing the homogeneous dose distribution and the critical organ doses in IMRTs, three to four times less treatment time, less low-dose volume, less leakage radiation, and less radiation scattering could be achieved when the DCAT technique is used similar to conventional methods. In short, DCAT, which is applicable in small target volumes, can also be successfully planned in large target volumes, such as the whole-brain.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.1
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• pp.65-68
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• 2004

CyberKnife is a stereotactic radiosurgery system which could be used to treat many tumors and lesions. It provides the surgeon unparalleled flexibility in targeting using a compact light linear accelerator mounted on a robotic arm. Advanced image guidance technology tracks patient and target position during treatment, ensuring accuracy without the use of an invasive head frame. CyberKnife with Dynamic Tracking Software is cleared to provide radiosurgery for lesions anywhere in the body when radiation treatment is indicated. It has often been used to radiosurgically treat otherwise untreatable tumors and malformations. Moreover, this instrument treats tumors at body sites, most of which are unreachable by other stereotactic systems. Compared with conventional radiotherapy, it is fundamentally different that using non-invasive, frameless, no excessive radiation exposure to normal tissue. In oral malignant neoplasm, surgical excision and radiation therapy should be tried first, additionally chemotherapy could be considered. However, after failure of conventional therapies, patients had poor systemic condition and surgical limitation. So, CyberKnife could be a suitable therapy. A 49 years man was referred in recurred mandibular cancer treated by radiotherapy. The tumor was considered inoperable, because of extensive invasion and was not expected to good response to conventional therapies. We experienced a case of CyberKnife after 4 cycle chemotherapies, so we report it with review of literature.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.4
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• pp.265-271
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• 2007

Radionuclide therapy has been an important field in nuclear medicine. In radionuclide therapy, relevant evaluation of Internally absorbed dose is essential for the achievement of efficient and sufficient treatment of incurable disease, and can be accomplish by means of accurate measurement of radioactivity in body and its changes with time. Recently, the advances of nuclear medicine imaging and multi modality imaging processing techniques can provide change of more accurate and easier measurement of the measures commented above, in cooperation of conventional imaging based approaches. in this review, basic concept for internal dosimetry using nuclear medicine imaging is summarized with several check points which should be considered In real practice.

• Journal of Korean Neurosurgical Society
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• v.30 no.10
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• pp.1224-1228
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• 2001

Germinoma is a rare central nervous system neoplasm in children and young adults. It is well known that a malignant primary neoplasm can be cured by conventional radiation therapy alone or reduced-volume and field irradiation in combination with chemotherapy. The authors report a very rare case of a pineal germinoma, which was completely disappeared after repeated diagnostic brain computed tomography(CT) with review of pertinent literature. There has been neither tumor recurrence nor metastasis during follow-up period.

• Journal of Korean Neurosurgical Society
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• v.38 no.1
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• pp.65-67
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• 2005

Intracranial chloroma may occur in leukemia, although they are rare. A 23-year-old female complained diplopia. Brain magnetic resonance MR imaging showed tumors in the both cavernous sinus, both tentorial and anterior falx. Gamma-Knife radiosurgery was performed with maximal dose; 20Gy, marginal dose; 10Gy. Peripheral blood smear revealed leukemia, and bone marrow aspiration biopsy showed acute lymphocytic leukemia. Two weeks later, MR image for the stereotactic biopsy noticed markedly decreased tumor size. Biopsy result was lymphocytic leukemia. She received conventional radiation therapy, chemotherapy, and bone marrow transplantation. Brain involvement by acute lymphocytic leukemia is very rare. Even though chloroma are sensitive to radiation therapy, prognosis is poor because of the gravity of the underlying disease and association with impending blast transformation. The authors reports a intracranial chloroma by acute lymphocytic leukemia.

• The Journal of Korean Society for Radiation Therapy
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• v.9 no.1
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• pp.64-70
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• 1997

The goal of radiation treatment planning is to deliver the dose to the patient within $5\%$ of that prescribed. We have often encountered the situation that the area which have not only several irregular contours but also tissue heterogeneities should be treated. With conventional devices such as wedges, missing tissue compensator. there are some limitations to achieve the uniform dose distribution in treatment volume. The use of CT simulator, 3-D planning system, computer-controlled milling machine enables it to deliver the dose uniformally. This report includes the whole procedure which have patient data acquisition 3D planning, computer-controlled milling, performance verification of 3D compensator, and TLD evaluation. We applied it for the treatment of head and heck cancer only. In Spite of the irregular contour and different electron density of tessue, we have achieved the uniformity of the dose distribution within ${\pm}3\%$ relatively. Although there are some problems which are not only verification of performance but uncertainties of using the new treatment device, we believe that the improvement of dosimetry will eliminate the uncertainties of that application. so the other lesions besides head and neck can will be ale to use the 3D compensator to achieve the dose uniformity

• Korean Journal of Head & Neck Oncology
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• v.6 no.1
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• pp.1-10
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• 1990

This review will be discussed the various causes of radiation failure for head and neck cancers from radiobiologic perspective and also provided a few clinical data to illustrate the basic principle. A knowledge about multiplicity of factors that may underlie failure of radiation treatment is essential for rational application of new treatment strategies. Furthermore, it is important to distinguish causes of failure that can be reduced or minimized by application of conventional treatment from one are potentially remediable by new treatment strategies, and one that are not amenable to some modification of radiotherapeutic approach.