• 대한두경부종양학회:학술대회논문집
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• 1990.11a
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• pp.22.1-22.1
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• 1990

• 대한두경부종양학회:학술대회논문집
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• 2007.11a
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• pp.210-210
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• 2007

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.129-138
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• 2018

Purpose : An aim of this study was to compare the effect of multi leaf collimator(MLC) types for high dimension radiotherapy in treatment sites used clinically. Material and Method : 70 patients with lung cancer, spine cancer, prostate cancer, whole pelvis, head and neck, breast cancer were included in this study. High definition(HD) MLC of TrueBeam STx (Varian Medical system, Palo Alto, CA) and millenium(M) MLC of VitalBeam (Varian Medical system, Palo Alto, CA) were used. Radiotherapy plans were performed for each patient under same treatment goals with Eclipse (Version 13.7, Varian Palo Alto USA, CA). To compare the indicators of the radiotherapy plans, planning target volume(PTV) coverage, conformity index(CI), homogeneity index(HI), and clinical indicators for each treatment sites in normal tissues were evaluated. To evaluate low dose distribution, $V_{30%}$ values were compared according to MLC types. Additionally, length and volume of targets for each treatment sites were investigated. Result : In stereotatictic body radiotherapy(SBRT) plan for lung, the average value of PTV coverage was reduced by 0.52 % with HD MLC. With SBRT plan using HD MLC for spine, the average value of PTV coverage decreased by 0.63 % and maximum dose decreased by 1.13 %. In the test of CI and HI, the values in SBRT plan with HD MLC for spine were 1.144, 1.079 and the values using M MLC were 1.160, 1.092 in SBRT plan for lung, The dose evaluation of critical organ was reduced by 1.48 % in the ipsilateral lung mean dose with HD MLC. In prostate cancer volumetric modulated arc therapy(VMAT) with HD MLC, the mean dose and the $V_{30}$ of bladder and the mean dose and the $V_{25}$ of rectum were reduced by 0.53 %, 1.42 %, 0.97 %, and 0.69 %, respectively (p<0.05). The average value of heart mean dose was reduced by 0.83 % in breast cancer VMAT with M MLC. Other assessment indices for treatment sites showed no significant difference between treatment plans with two types of MLC. Conclusion : Using HD MLC had a positive impact on the PTV coverage and normal tissue sparing in usually short or small targets such as lung and spine SBRT and prostate VMAT. But, there was no significant difference in targets with long and large such as lung, head and neck, and whole pelvis for VMAT.

• Korean Journal of Head & Neck Oncology
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• v.13 no.2
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• pp.228-234
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• 1997

Squamous cell carcinoma originating in the parotid gland has rare occurrence. The primary squamous cell carcinoma of the parotid gland comprise about 0.3% and 9.8% of all parotid malignant tumor. We investigated the clinical behavior and treatment outcome of patients with primary squamous cell carcinoma of the parotid gland. We reviewed all cases of possible primary squamous cell carcinoma of the parotid gland treated at Yonsei Cancer Center, Seoul, Korea, from 1981 through 1995. A total of 128 had primary parotid malignancy. Metastatic squamous cell carcinoma and mucoepidermoid carcinoma were excluded in this study. Ten cases of primary squamous cell carcinoma of the parotid gland were identified. 6 cases of them are men & 4 cases are women. The age of patients ranged from 31 to 68 years with median age of 55 years. On physical examination, 5 cases had palpated cervical neck node and 6 cases had facial nerve palsy. Staging was done according to the current guidelines established by the American Joint Committee on Cancer (1992). Two cases were stage I, 1 in stage III, and 7 in stage IV. Six cases were performed operation and postoperative radiation therapy. Four cases were treated by curative radiation therapy, dose of more than 65 Gy on parotid gland region. The 5 year actual survival rate and the 5 year disease free survival rate were 30.8%, and 40.0%. Initial complete response rate was 70% for all patients. Local failure were occurred 3 of 7 patients with local controlled cases, failure sites were primary site, ipsilateral cervical neck node, contralateral supraclavicular node. Most recurrences developed within 1 year of initial treatment. Distant metastasis was appeared 2 of 3 patients who did not achieved local control. Primary squamous cell carcinoma of the parotid gland occured infrequently. A retrospective study at the Yonsei Cancer Center indicates incidence of 7.8%. At diagnosis, advanced stage, neck node presentation, facial nerve paralysis were associated with a poor prognosis. These results may suggested that radical surgical excision may be treatment of choice and that planned postoperative radiotherapy may be bendicial for reducing locoregional recurrence rates.

• Korean Journal of Head & Neck Oncology
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• v.19 no.1
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• pp.16-20
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• 2003

Objectives: Radiotherapy is an effective treatment in the initial management of T1 glottic carcinoma, but local recurrent or residual tumor growth is found in approximately 10% of the patients. Even in recurrence or residual tumor, in highly selected cases, conservation surgery with preservation of a portion of the larynx is feasible. So we investigated the efficacy of salvage vertical partial laryngectomy for recurrent glottic carcinoma after irradiation. Material and Methods: Retrospectively we reviewed a consecutive series of 10 patients treated by conservative vertical partial laryngectomy of the larynx for radiation-failure, recurrent T1 glottic squamous cell carcinoma treated at Severance Hospital from 1994 to 2002. Results: Local recurrence developed in 4 patients (40%). Two patient was salvaged by further totallaryngectomy. Successful salvage was achieved finally in 8 (80%) of the 10 patients. There was no operative mortality. Postoperative perichondritis was developed in two patients. One was resolved by conservative treatment, but the other has underwent the total laryngectomy. Conclusion: A vertical partial laryngectomy in case of recurrent glottic carcinoma after a course of irridation should be the therapy of choice when stringent criteria are observed.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.16
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• pp.6649-6655
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• 2014

Radiation therapy is an important treatment for head and neck squamous cell carcinoma (HNSCC). However, how to promote radiation sensitivity in HNSCC remains a challenge. This study aimed to investigate the radiosensitizing effects of fenofibrate on HNSCC and explore the underlying mechanisms. HNSCC cell lines CNE-2 and KB were subjected to ionizing radiation (IR), in the presence or absence of fenofibrate treatment. Cell growth and survival, apoptosis and cell cycle were evaluated. In addition, CNE-2 cells were xenografted into nude mice and subjected to IR and/or fenofibrate treatment. The expression of cyclinB and CDK1 was detected by Western blotting. Our results showed that fenofibrate efficiently radiosensitized HNSCC cells and xenografts in mice, and induced apoptosis and G2/M arrest via reducing the activity of the CDK1/cyclinB1 kinase complex. These data suggest that fenofibrate could be a promising radiosensitizer for HNSCC radiotherapy.

• Korean Journal of Head & Neck Oncology
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• v.34 no.1
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• pp.9-13
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• 2018

Background/Objectives: Brain metastasis (BM) is a rare form of distant metastasis with papillary thyroid cancer (PTC). Patients with BM of PTC carry a poor prognosis. The aim of this study was to contribute to the understanding of this disease by analyzing patients with BM of PTC. Materials & Methods: Between March 2003 and December 2013, the patient database was conducted to identify thyroid cancer patients treated. Among the 22,758 thyroid cancer patients, 14 (0.06 %) were identified to have metastasis to the brain during follow-up. The medical records of 14 patients with BM were retrospectively reviewed, focusing on the following: patient characteristics, synchronous or previous distant metastasis, treatments including whole brain radiotherapy (WBRT), stereotactic radiosurgery (SRS) and surgery, and characteristics on radiologic findings, time interval between first diagnosis of primary thyroid cancer and BM and survival after BM. Results: The mean age at initial diagnosis and BM were $50.9{\pm}15.8years$ and $61.3{\pm}12.7years$. The mean duration between initial diagnosis and BM was $10.4{\pm}7.9years$. Patients were treated with varied combinations of surgery, SRS and WBRT except 4 patients who had refused treatment. The median overall survival (OS) time after BM diagnosis was 10 months (range 1 - 19). Patients receiving treatment (WBRT and/or surgery, SRS) had a significant longer median OS of 16.5 months in comparison to 3.5 months for those treated without treatment. (p = 0.005) Conclusion: Patients who received aggressive treatment had a longer OS than those with only supportive care. Treatment such as surgery, SRS and WBRT should be considered in patients with BM.

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.225-231
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• 2003

Up-front irradiation technique as 3-dimensional conformation, or intensity modulation has kept large proportion of brain tumors from being complicated with acute radiation reactions in the normal tissue during or shortly after radiotherapy. For years, we've cannot help but counting on 2-D vertex beam technique to reduce acute reactions in the brain tumor patients because we're not equipped with 3-dimensional planning system. We analyzed its advantages and limitations in the clinical application. From 1998 to 2001, vertex or oblique vertex beams were applied to 35 patients with primary brain tumor and 25 among them were eligible for this analysis. Vertex(V) plans were optimized on the reconstructed coronal planes. As the control, we took the bilateral opposed techniques(BL) otherwise being applied. We compared the volumes included in 105% to 50% isodose lines of each plan. We also measured the radiation dose at various extracranial sites with TLD. With vertex techniques, we reduced the irradiated volumes of contralateral hemisphere and prevented middle ear effusion at contralateral side. But the low dose volume increased outside 100%; the ratio of V to BL in irradiated volume included in 100%, 80%, 50% was 0.55+/-0.10, 0.61+/-0.10, and 1.22+/-0.21, respectively. The hot area within 100% isodose line almost disappeared with vertex plan; the ratio of V to BL in irradiated volume included in 103%, 105%, 108% was 0.14+/-0.14, 0.05./-0.17, 0.00, respectively. The dose distribution within 100% isodose line became more homogeneous; the ratio of volume included in 103% and 105% to 100% was 0.62+/-0.14 and 0.26+/-0.16 in BL whereas was 0.16+/-0.16 and 0.02+/-0.04 in V. With the vertex techniques, extracranial dose increased up to $1{\sim}3%$ of maximum dose in the head and neck region except submandibular area where dose ranged 1 to 21%. From this data, vertex beam technique was quite effective in reduction of unnecessary irradiation to the contralateral hemispheres, integral dose, obtaining dose homogeneity in the clinical target. But it was associated with volume increment of low dose area in the brain and irradiation toward the head and neck region otherwise being not irradiated at all. Thus, this 2-D vertex technique can be a useful quasi-conformal method before getting 3-D apparatus.

• Progress in Medical Physics
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• v.32 no.3
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• pp.70-81
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• 2021

Purpose: This study was designed to investigate the dosimetric difference between intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) in head and neck cancer (HNC). The study primarily focuses on low-dose spillage evaluation between these two techniques. Methods: This retrospective study involved 45 patients with HNC. The treatment plans were generated using the IMRT and VMAT techniques for all patients. Dosimetric comparisons were performed in terms of target coverage, organ-at-risk (OAR) sparing, and various parameters, including conformity index, uniformity index, homogeneity index, conformation number, low-dose volumes, and normal tissue integral dose (NTID). Results: No significant (P>0.05) difference in planning target volume coverage (D_95%) was observed between IMRT and VMAT plans for supraglottic larynx, hard palate, and tongue cancers. A decrease in dose volumes ranging from 1 Gy to 30 Gy was observed for VMAT plans compared with those for IMRT plans, except for V_1Gy and V_30Gy for supraglottic larynx cancer and V_1Gy for tongue cancer. Moreover, decreases (P<0.05) in NTID were observed for VMAT plans compared with that for IMRT plans in supraglottic larynx (4.50%), hard palate (12.80%), and tongue (7.76%) cancers. In contrast, a slight increase in monitor units for VMAT compared with those for IMRT in supraglottic larynx (0.46%), hard palate (2.54%), and tongue (7.56%) cancers. Conclusions: For advanced-stage HNC, both IMRT and VMAT offer satisfactory clinical plans. VMAT offers a conformal and homogeneous dose distribution with comparable OAR sparing and higher dose falloff outside the target volume than IMRT, which provides an edge to reduce the risk of secondary malignancies for HNC over IMRT.

• Journal of radiological science and technology
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• v.35 no.4
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• pp.335-343
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• 2012

Intensity-modulated radiotherapy(IMRT) have the ability to provide better dose conformity and sparing of critical normal tissues than three-dimensional radiotherapy(3DCRT). Especially, with the benefit of health insurance in 2011, its use now increasingly in many modern radiotherapy departments. Also the use of linear accelerator with high-energy photon beams over 10 MV is increasing. As is well known, these linacs have the capacity to produce photonueutrons due to photonuclear reactions in materials with a large atomic number such as the target, flattening filters, collimators, and multi-leaf collimators(MLC). MLC-based IMRT treatments increase the monitor units and the probability of production of photoneutrons from photon-induced nuclear reactions. The purpose of this study is to quantitatively evaluate the dose of photoneutrons produced from 3DCRT and IMRT technique for Rando phantom in cervical cancer. We performed the treatment plans with 3DCRT and IMRT technique using Rando phantom for treatment of cervical cancer. An Rando phantom placed on the couch in the supine position was irradiated using 15 MV photon beams. Optically stimulated luminescence dosimeters(OSLD) were attached to 4 different locations (abdomen, chest, head and neck, eyes) and from center of field size and measured 5 times each of locations. Measured neutron dose from IMRT technique increased by 9.0, 8.6, 8.8, and 14 times than 3DCRT technique for abdomen, chest, head and neck, and eyes, respectively. When using IMRT with 15 MV photonbeams, the photoneutrons contributed a significant portion on out-of-field. It is difficult to prevent high energy photon beams to produce the phtoneutrons due to physical properties, if necessary, It is difficult to prevent high energy photon beams to produce the phtoneutrons due to physical properties, if necessary, it is need to provide the additional safe shielding on a linear accelerator and should therefore reduce the out-of-field dose.