• Journal of radiological science and technology
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• v.42 no.6
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• pp.413-422
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• 2019

Heavy ion particle, represented carbon ion, radiotherapy is currently most advanced radiation therapy technique. Conventional radiation therapy has made remarkable changes over a relatively short period of time and leading various developments such as intensity modulated radiation therapy, 4D radiation therapy, image guided radiation therapy, and high precisional therapy. However, the biological and physical superiority of particle radiation, represented by Bragg peak, can give the maximum dose to tumor and minimal dose to surrounding normal tissues in the treatment of cancers in various areas surrounded by radiation-sensitive normal tissues. However, despite these advantages, there are some limitations and factors to consider. First, there is not enough evidence, such as large-scale randomized, prospective phase III trials, for the clinical application. Secondly, additional studies are needed to establish a very limited number of treatment facilities, uncertainty about the demand for heavy particle treatment, parallel with convetional radiotherapy or indications. In addition, Bragg peak of the heavy particles can greatly reduce the dose to the normal tissues front and behind the tumor compared to the photon or protons. High precision and accuracy are needed for treatment planning and treatment, especially for lungs or livers with large respiratory movements. Currently, the introduction of the heavy particle therapy device is in progress, and therefore, it is expected that more research will be active.

• Radiation Oncology Journal
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• v.10 no.1
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• pp.15-20
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• 1992

A total of 20 patients (male: female=10:10, adult:children=8:12) with brainstem tumors had been received radiation therapy in the Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine between 1980 and 1990. Thirteen of 20 patients were treated with conventional radiation therapy (before 1989, 180~200 cGy per fraction, 5 days a week, total dose 4680~5400 cGy), and seven patients were treated with hyperfractionated radiation therapy (in 1990, 100 cGy per fraction, twice daily 10 fractions a week, total dose 7200 cGy). Median follow up Periods for conventional radiation therapy group and hyperfractionated radiation therapy group were 36 months and 10 months, respectively. Four of 20 Patients had histopathologic diagnosis prior to treatment; 3 cases were low grade astrocytoma and 1 case was high grade astrocytoma. Overall 2-year actuarial survival rate was 30%. The prognosis of patients with a longer duration of symptom and sign was better (60%, vs 12%), and the adult (52%) was better than children (14%). There was no significant difference between the focal (29%) and diffuse (26%) type. The initial clinical response was better in the hyperfractionated radiation therapy group. Because of the relatively small number of Patients and short follow up Period in hyperfractionated radiation therapy group, there was no comparison between two group.

• Radiation Oncology Journal
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• v.11 no.2
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• pp.277-283
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• 1993

Background: We peformed a retroslective study in patients with previously untreated advanced (Stage III or IV) laryngeal and hypopharyngeal cancer to compare the results of induction chemotherapy followed by definitive radiation therapy (CT+ RT) with those of conventional laryngectomy and postoperative radiation therapy (OP + RT). Method: Between 1985 and 1990, twenty-four patients were treated with two or three courses of chemotherapy and radiation therapy (66-75 Gy). Twenty-five patients were received laryngectomy and radical neck dissection (except 3 patients) and postoperative radiation therapy (55~64 Gy). Result: After a median fellow-up of 20 months, the actusrial 5-year overall survival rate was $24\%$ (chemotherapy group) and $36\%,$ (op group). (P>0.1). The local control rate was the $65\%,$ (13/20) and $68.2\%,$ (15/22). (p>0.1). The rate of laryngeal preservation was $65\%$ (13/20) in chemotherapy group. Conclusion: Induction chemotherapy and definitive radiation therapy can be effective in preserving the larynx in a high percentage of patients with advanced laryngeal and hypopharyngeal cancer.

• 대한방사선치료학회:학술대회논문집
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• 2004.03a
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• pp.8-8
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• 2004

• The Journal of Korean Society for Radiation Therapy
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• v.2 no.1
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• pp.75-80
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• 1987

Intraoperative Radiation therapy (IORT) is a cancer treatment modality in which resectable masses or organs are removed surgically and residual cancer calls are sterilized by irradiation with a single massive dose during while patient is still anesthetized. Because it is possible that the turner mass can be visualized directly at the time of surgical exploration, tumor volume can be determined more precisely and at the same tin e sensitive adjacent structures can be pulled aside from the irradiation. With these theoretical advantages as compare to conventional external irradiation, IORT can improve the therapeutic ratio of tumor control to normal tissue injury. Yonsei cancer center initiated a pilot study of multidisciplinary IORT program in february of 1986 for the fist attempt in Korea. IORT Was performed in 7 patients with stomach cancer by using existing NELAC-1018 Linear Accelerator treatment room as a surgical suite. IOTR team included department of surgery, Department of Anethesiology, Department of Clinical pathology, operating room nursing personal and Department of radiation oncology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6187-6192
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• 2014

The use of WBRT(whole brain radiation therapy) has increased due to the increase in the incidence of metastatic brain tumors. The development of radiation therapy techniques is expected to improve the quality of life. The VMAT (Volumetric Modulated Arc Therapy) is an excellent treatment technique that can distinguish the dose in each volume. Therefore, this study compared conventional WBRT and VMAT for hair loss according to the scalp dose using a head phantom. The CI (Conformity Index), HI (Homogeneity Index) and QOC (Quality of Coverage) were measured brain tissue. A 20 percent and 50 percent dose was measured at the scalp, eyeball, lens, and c-spine. Conventional WBRT is excellent at 10 percent of brain tissue. VMAT is far superior at 1000 percent at the other organs. VMAT at the prescribed dose can be used as radiation therapy of metastatic brain tumors with less hair loss.

• Progress in Medical Physics
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• v.11 no.1
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• pp.85-90
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• 2000

In radiation therapy, the effects of radiation are decided total dose, total treatment times and number of radiation dose fractions. We considered that total dose, total treatment times and number of radiation dose fractions in intensity modulation radiation therapy(IMRT) infuence tumor cell killing. The goal of three dimensional conformal radiation therapy(3DCRT) in radiation therapy is to conform the partial distribution of the prescribed radiation dose to the precise 3D configuration of the tumor, and at the same time, to minimize the dose to the surrounding normal tissues. To optimize treatment volume of tumor, treatment volume will be same tumor volume. All IMRT compare to conventional treatment plus boost IMRT when total dose irradiated 75 - 90 Gy. Because of biological effect, total dose are decreased 12.5 - l5Gy in all IMRT.

• Radiation Oncology Journal
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• v.16 no.4
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• pp.455-467
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• 1998

Purpose : To evaluate influences associated with radiation treatment planning obtained with the patient breathing freely. Materials and Methods : We compared reduction or elimination of planning target volume (PTV) margins with 2-D conventional plan with inclusion of PTV margins associated with breathing with 3-D conformal therapy. The respiratory non gated 3-D conformal treatment plans were compared with respiratory gated conventional 2-D plans in 4 patients with hepatocellular carcinomas. Isodose distribution, dose statistics, and dose volume histogram (DVH) of PTVs were used to evaluate differences between respiratory gated conventional 2-D plans and respiratory non gated 3-D conformal treatment plans. In addition. the risk of radiation exposure of surrounding normal liver and organs are evaluated by means of DVH and normal tissue complication probabilities (NTCPs). Results : The vertical movement of liver ranged 2-3 cm in all patients. We found no difference between respiratory gated 2-D plans and 3-D conformal treatment plans with the patients breathing freely. Treatment planning using DVH analysis of PTV and the normal liver was used for all patients. DVH and calculated NTCP showed no difference in respiratory gated 2-D plans and respiratory non gated 3-D conformal treatment plans. Conclusion : Respiratory gated radiation therapy was very important in hepatic tumors because radiation induced hepatitis was dependent on remaining normal liver volume. Further investigational studies for respiratory gated radiation.

• Radiation Oncology Journal
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• v.33 no.4
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• pp.265-275
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• 2015

Despite the increasing use of stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS) in recent years, the biological base of these high-dose hypo-fractionated radiotherapy modalities has been elusive. Given that most human tumors contain radioresistant hypoxic tumor cells, the radiobiological principles for the conventional multiple-fractionated radiotherapy cannot account for the high efficacy of SBRT and SRS. Recent emerging evidence strongly indicates that SBRT and SRS not only directly kill tumor cells, but also destroy the tumor vascular beds, thereby deteriorating intratumor microenvironment leading to indirect tumor cell death. Furthermore, indications are that the massive release of tumor antigens from the tumor cells directly and indirectly killed by SBRT and SRS stimulate anti-tumor immunity, thereby suppressing recurrence and metastatic tumor growth. The reoxygenation, repair, repopulation, and redistribution, which are important components in the response of tumors to conventional fractionated radiotherapy, play relatively little role in SBRT and SRS. The linear-quadratic model, which accounts for only direct cell death has been suggested to overestimate the cell death by high dose per fraction irradiation. However, the model may in some clinical cases incidentally do not overestimate total cell death because high-dose irradiation causes additional cell death through indirect mechanisms. For the improvement of the efficacy of SBRT and SRS, further investigation is warranted to gain detailed insights into the mechanisms underlying the SBRT and SRS.

• Progress in Medical Physics
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• v.32 no.4
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• pp.83-91
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• 2021

Various types of high-precision radiotherapy, such as intensity-modulated radiation therapy (IMRT), tomotherapy (Tomo), and stereotactic body radiation therapy have been available since 1997. After being covered by insurance in 2015, the number of IMRT cases rapidly increased 18-fold from 2011 to 2018 in Korea. IMRT, which uses a high-beam irradiation monitor unit, requires higher shielding conditions than conventional radiation treatments. However, to date, research on the shielding of facilities using IMRT and the current understanding of its status are insufficient, and detailed safety regulation procedures have not been established. This study investigated the recommended criteria for the shielding evaluation of facilities using medical linear accelerators (LINACs), including 1) the current status of safety management regulations and systems in domestic and international facilities using medical LINACs and 2) the current status of the recommended standards for safety management in domestic and international facilities using medical LINACs. It is necessary to develop and introduce a safety management system for facilities using LINACs for clinical applications that is suitable for the domestic medical environment and corresponds to the safety management systems for LINACs used overseas.