• Radiation Oncology Journal
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• v.28 no.3
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• pp.141-146
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• 2010

Purpose: We examined the radioprotective effects of 5-androstendiol (5-AED), a natural hormone produced in the reticularis of the adrenal cortex, as a result of intestinal damage in gamma-irradiated C3H/HeN mice. Materials and Methods: Thirty mice (C3H/HeN) were divided into three groups; 1) non-irradiated control group, 2) irradiated group, and 3) 5-AED-treated group prior to irradiation. Next, 5-AED (50 mg/kg per body weight) was subcutaneously injected 24 hours before irradiation. The mice were whole-body irradiated with 10 Gy for the histological examination of jejunal crypt survival and the determination of the villus morphology including crypt depth, crypt size, number of villi, villus height, and length of basal lamina, as well as 5 Gy for the detection of apoptosis. Results: The 5-AED pre-treated group significantly increased the survival of the jejunal crypt, compared to irradiation controls (p<0.05 vs. irradiation controls at 3.5 days after 10 Gy). The evaluation of morphological changes revealed that the administration of 5-AED reduced the radiation-induced intestinal damages such as villus shortening and increased length of the basal lamina of enterocytes (p<0.05 vs irradiation controls on 3.5 day after 10 Gy, respectively). The administration of 5-AED decreased the radiation-induced apoptosis in the intestinal crypt, with no significant difference between the vehicle and 5-AED at 12 hours after 5 Gy. Conclusion: The results of this study suggest that the administration of 5-AED has a protective effect on intestinal damage induced by $\gamma$-irradiation. In turn, these results suggest that 5-AED could be a useful candidate for radioprotection against intestinal mucosal injury following irradiation.

• Journal of Radiation Protection and Research
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• v.36 no.1
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• pp.23-27
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• 2011

In order to confirm feasibility of MOSFET modality in use of in.vivo dosimetry, evaluation of gonad shielding in order to minimize gonadal dose of patients undergoing radiotherapy by using MOSFET modality was performed. Gonadal dose of patients undergoing radiotherapy for rectal cancer in the department of radiation oncology of Seoul National University Hospital since 2009 was measured. 6 MV and 15 MV photon beams emitted from Varian 21EX LINAC were used for radiotherapy. In order to minimize exposed dose caused by the scattered ray not only from collimator of LINAC but also from treatment region inside radiation field, we used box.shaped lead shielding material. The shielding material was made of the lead block and consists of $7.5\; cm\;{\times}\;9.5\;cm\;{\times}5.5\;cm$ sized case and $9\;cm\;{\times}\;9.5\;cm\;{\times}\;1\;cm$ sized cover. Dosimetry for evaluation of gonad shielding was done with MOSFET modality. By protecting with gonad shielding material, average gonadal dose of patients was decreased by 23.07% compared with reference dose outside of the shielding material. Average delivered gonadal dose inside the shielding material was 0.01 Gy. By the result of MOSFET dosimetry, we verified that gonadal dose was decreased by using gonad shielding material. In compare with TLD dosimetry, we could measure the exposed dose easily and precisely with MOSFET modality.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.150-156
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• 2000

Purpose : Stereotactic radiation therapy (SRT) can deliver highly focused radiation to a small and spherical target lesion with very high degree of mechanical accuracy. For non-spherical and large lesions, however, inclusion of the neighboring normal structures within the high dose radiation volume is inevitable in SRT This is to report the beam shaping using the partial closure of the independent jaw in SRT and the verification of dose calculation and the dose display using a home-made soft ware. Materials and Methods : Authors adopted the idea to partially close one or more independent collimator jaw(5) in addition to the circular collimator cones to shield the neighboring normal structures while keeping the target lesion within the radiation beam field at all angles along the arc trajectory. The output factors (OF's) and the tissue-maximum ratios (TMR's) were measured using the micro ion chamber in the water phantom dosimetry system, and were compared with the theoretical calculations. A film dosimetry procedure was peformed to obtain the depth dose profiles at 5 cm, and they were also compared with the theoretical calculations, where the radiation dose would depend on the actual area of irradiation. Authors incorporated this algorithm into the home-made SRT software for the isodose calculation and display, and was tried on an example case with single brain metastasis. The dose-volume histograms (DVH's) of the planning target volume (PTV) and the normal brain derived by the control plan were reciprocally compared with those derived by the plan using the same arc arrangement plus the independent collimator jaw closure. Results : When using 5.0 cm diameter collimator, the measurements of the OF's and the TMR's with one independent jaw set at 30 mm (unblocked), 15.5 mm, 8.6 mm, and 0 mm from th central beam axis showed good correlation to the theoretical calculation within 0.5% and 0.3% error range. The dose profiles at 5 cm depth obtained by the film dosimetry also showed very good correlation to the theoretical calculations. The isodose profiles obtained on the home-made software demonstrated a slightly more conformal dose distribution around the target lesion by using the independent jaw closure, where the DVH's of the PTV were almost equivalent on the two plans, while the DVH's for the normal brain showed that less volume of the normal brain receiving high radiation dose by using this modification than the control plan employing the circular collimator cone only. Conclusions : With the beam shaping modification using the independent jaw closure, authors have realized wider clinical application of SRT with more conformal dose planning. Authors believe that SRT, with beam shaping ideas and efforts, should no longer be limited to the small spherical lesions, but be more widely applied to rather irregularly shaped tumors in the intracranial and the head and neck regions.

• Radiation Oncology Journal
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• v.17 no.2
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• pp.158-165
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• 1999

Purpose : To investigate the percentage of colonies wi1h16or more cells distribution of human skin fibroblast according to in vitro aging, and to evaluate the relationship between percentage of colonies with 10 or more cells and in vivo donor age in human skin fibroblast culture. Material and Method : C1, C2, C3a, and C3b human skin fibroblast samples from three breast cancer patients were used as subjects. The C1, C2, and C3a donor were 44, 54, and 55 years old, respectively. C3a and C3b cells were isolated from the same person. Single cell suspension of skin fibroblasts was prepared with primary explant technique. One hundred cells are plated into 100m1 tissue culture flask and cultured for two weeks. The colony size was defined as colonies with 16 or more cells. The cultured cell was stained with crystal violet, and number of cells in each colony was determined with stereo microscope at $\times$10 magnification. Passage number of C1, C2, C3a and C3b skin fibroblast were 12th, 17th, and 14th, respectively. Results : Percentage of colonies with 16 or more cells of skin fibroblast samples decreased with increasing in vitro passage number. In contrast, cumulative population doublings of skin fibroblast sample increased with increasing in vitro passage number. Percentage of colonies with 16 or more cells also decreased with increasing population doublings in human skin fibroblast culture. There was strong correlation with percentage of colonies with 16 or more cells and population doublings En C3a skin fibroblast sampie. At the same point of population doublings, the percentage of colonies with 16 or more cells of the young C1 donor was higher level than the old C3a donor. Conclusion : The population doublings increased with increasing in vitro passage number but percentage of colonies with 16 or more cells decreased. The results of this study imply that percentage of colonies with 16 or more cell is useful as a indicator of in vitro human skin fibroblast aging and may estimate the in vivo donor age.

• Radiation Oncology Journal
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• v.16 no.4
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• pp.505-515
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• 1998

Purpose : This study is intended to understand the sensitometric characteristics and the emulsion properties of the commercially available CEA TVS film in comparison with the Kodak X-Omat V film. Materials and Methods : For this purpose, we have formulated an analytic expression of the characteristic curves for x-ray film exposed to mixed radiation of electrons, photons, and visible light. This mathematical expression was developed based on reaction-rate and target-hit theories. Unlike previous expressions. it relates optical density to emulsion properties such as grain size and silver bromide content We have also developed a quantity which characterizes the film response to visible light relative to that to photons and electrons. This quantity could be expressed as a function of grain area. Thus, we have developed mathematical expressions and quantities with which the emulsion properties of the films can be revealed based on the sensitometric characteristics. Demonstrating the use of this analytical study, we exposed CEA and Kodak verification films to the mixed radiation of electrons, photons, and visible light, and interpreted the experimental results accordingly. Results : We have demonstrated that: (1) the saturation density increases as the silver bromide content increases, (2) the time required to reach the threshold dose (to which the film begins to respond) when films are exposed to visible light decreases as the grain size increases, and (3) the CEA film contains more silver bromide. whereas the Kodak film contains larger grains. These findings were supported by the data provided by the manufacturers afterward. Conclusion : This study presented an analytical and experimental basis for understanding the response of X-ray film with respect to the emulsion properties.

• The Korean Journal of Nuclear Medicine
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• v.36 no.6
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• pp.344-356
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• 2002

Purpose: RBC blood pool SPECT has been used to diagnose focal liver lesion such as hemangioma owing to its high specificity. However, low spatial resolution is a major limitation of this modality. Recently, ordered subset expectation maximization (OSEM) has been introduced to obtain tomographic images for clinical application. We compared this new modified iterative reconstruction method, OSEM with conventional filtered back projection (FBP) in imaging of liver hemangioma. Materials and Methods: Sixty four projection data were acquired using dual head gamma camera in 28 lesions of 24 patients with cavernous hemangioma of liver and these raw data were transferred to LINUX based personal computer. After the replacement of header file as interfile, OSEM was performed under various conditions of subsets (1,2,4,8,16, and 32) and iteration numbers (1,2,4,8, and 16) to obtain the best setting for liver imaging. The best condition for imaging in our investigation was considered to be 4 iterations and 16 subsets. After then, all the images were processed by both FBP and OSEM. Three experts reviewed these images without any information. Results: According to blind review of 28 lesions, OSEM images revealed at least same or better image quality than those of FBP in nearly all cases. Although there showed no significant difference in detection of large lesions more than 3 cm, 5 lesions with 1.5 to 3 cm in diameter were detected by OSEM only. However, both techniques failed to depict 4 cases of small lesions less than 1.5 cm. Conclusion: OSEM revealed better contrast and define in depiction of liver hemangioma as well as higher sensitivity in detection of small lesions. Furthermore this reconstruction method dose not require high performance computer system or long reconstruction time, therefore OSEM is supposed to be good method that can be applied to RBC blood pool SPECT for the diagnosis of liver hemangioma.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.2
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• pp.101-108
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• 2017

Purpose: The proton used in proton therapy has a characteristic of giving a small dose to the normal tissue in front of the tumor site while forming a Bragg peak at the cancer tissue site and giving up the maximum dose and disappearing immediately. It is very important to verify the proton arrival position. In this study, we used the off-line PET CT method to measure the distribution of positron emitted from nucleons such as 11C (half-life = 20 min), 150 (half-life = 2 min) and 13N The range and distal falloff point of the proton were verified by measurement. Materials and Methods: In the IEC 2001 Body Phantom, 37 mm, 28 mm, and 22 mm spheres were inserted. The phantom was filled with water to obtain a CT image for each sphere size. To verify the proton range and distal falloff points, As a treatment planning system, SOBP were set at 46 mm on 37 mm sphere, 37 mm on 28 mm, and 33 mm on 22 mm sphere for each sphere size. The proton was scanned in the same center with a single beam of Gantry 0 degree by the scanning method. The phantom was scanned using PET-CT equipment. In the PET-CT image acquisition method, 50 images were acquired per minute, four ROIs including the spheres in the phantom were set, and 10 images were reconstructed. The activity profile according to the depth was compared to the dose profile according to the sphere size established in the treatment plan Results: The PET-CT activity profile decreased rapidly at the distal falloff position in the 37 mm, 28 mm, and 22 mm spheres as well as the dose profile. However, in the SOBP section, which is a range for evaluating the range, the results in the proximal part of the activity profile are different from those of the dose profile, and the distal falloff position is compared with the proton therapy plan and PET-CT As a result, the maximum difference of 1.4 mm at the 50 % point of the Max dose, 1.1 mm at the 45 % point at the 28 mm sphere, and the difference at the 22 mm sphere at the maximum point of 1.2 mm were all less than 1.5 mm in the 37 mm sphere. Conclusion: To maximize the advantages of proton therapy, it is very important to verify the range of the proton beam. In this study, the proton range was confirmed by the SOBP and the distal falloff position of the proton beam using PET-CT. As a result, the difference of the distally falloff position between the activity distribution measured by PET-CT and the proton therapy plan was 1.4 mm, respectively. This may be used as a reference for the dose margin applied in the proton therapy plan.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.217-222
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• 1999

Purpose : To evaluate prognostic factors and survival rates of the patients who received radiation therapy for locally recurrent uterine cervical cancer after curative surgery. Materials and Methods : Between October 1983 and July 1990, fifty three patients who received radiation therapy for locally recurrent cervical cancer after curative surgery at the Department of Therapeutic Radiology, Kangnam St. Mary's Hospital, The Catholic University of Korea were analysed retrospectively. Age at diagnosis ranged from 33 to 69 years (median 53 years). Pathological analysis showed that forty five ($84.9\%$) patients had squamous cell carcinoma, seven ($13.2\%$) patients had adenocarcinoma, and one (1.9%) patient had adenosquamous cell carcinoma. The interval between hysterectomy and tumor recurrence ranged from 2 months to 25 years (mean 34.4 months). The recurrent sites were vaginal stump in 41 patients ($77.4\%$) and pelvic side wall in 12 patients ($22.6\%$). Recurrent tumor size was devided into two groups : less than 3 cm in 43 patients ($81.1\%$) and more than 3 cm in 10 patients ($18.9\%$). External beam irradiation of whole pelvis was done first up to 46.8 Gy to 50.4 Gy in 5 weeks to 6 weeks, followed by either external beam boost to the recurrent site in 18 patients ($34\%$) or intracavitary irradiation in 24 patients ($45.3\%$). Total dose of radiation ranged from 46.8 Gy to 111 Gy (median 70.2 Gy). Follow up period ranged from 2 to 153 months with a median of 35 months. Results : Overall response rate was $66\%$ (35/53). Among them, six patients ($17.1\%$) relapsed between 7 months and 116 months after radiation therapy (mean 47.7 months), Therefore overall recurrence rate was $45.3\%$. Overall five-year actuarial survival rate was $78.9\%$ and distant failure rate was $10\%$ (5/50). The significant prognostic factors affecting survival rate were interval between primary surgery and tumor recurrence (p=0.0055), recurrent tumor size (p=0.0039), and initial response to radiation therapy (p=0.0428). Complications were observed in 10 ($20/%$) patients, which included mild to moderate lower gastrointestinal, genitourinary, or skin manifestations. One patient died of pulmonary embolism just after intracavitary irradiation. Conclustion : Radiation therapy is the effective treatment for the patients with locally recurrent cervical cancer after curative surgery. These results suggest that interval between primary surgery and tumor recurrence, recurrent tumor size, and initial response to radiation therapy were significant prognostic factors for recurrent cervical cancer.

• Tuberculosis and Respiratory Diseases
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• v.41 no.2
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• pp.87-96
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• 1994

Background : Since tumor necrosis factor was discovered in 1975, TNF has been well known about its cytotoxic effect on tumor cells in vivo and in vitro. According to the recent improvement of molecular biological techinques, it is possible that exogenous TNF gene is transferred to tumor cells and is expressed in theirs. By virtue of TNF gene transfer, we have expected that TNF expressed in TNF-gene-transferred tumor cells would kill tumor cells in vivo without systemic side effect. The expected mechanisms in which antitumor effects of TNF expressed in TNF-gene-transferred tumor cells are working would be as followings. In the first mechanism, TNF expressed in TNF-gene-transferred tumor cells would kill tumor cells around(like homicide). In the second mechanism, TNF expressed in TNF-gene-transferred tumor cells would kill themselves(like suicide). In the third mechanism, TNF expressed in TNF-gene-transferred tumor cells would recruit immune effector cells and kill tumor cells indirectly. In the last mechanism, TNF expressed in TNF-gene-transferred tumor cells would augment cytokine such as interferon-$\gamma$ to kill tumor cells. Among these four mechanisms of antitumor effect, only the second mechanism has not been established yet. Therefore, to elucidate the second mechanism, We performed this study. Method : We transferred TNF-$\alpha$ gene to NCI-H2058, a human mesothelioma cell line and WEHI164, a murine fibrosarcoma cell line by using retroviral vector(pLT12SNTNF). And, We determined by using MTT assay whether TNF expressed in TNF-gene-transferred tumor cell lines would kill themselves like suicide or not. Then, if TNF-gene-transferred tumor cell lines would not suicide themselves, I would know more about the TNF sensitivity of TNF-gene-transferred tumor cell lines to exogenous TNF also by MTT assay. Result : NCI-H2058 and WEHI164 which were sensitive to TNF, became far less sensitive to endogenous and exogenous TNF after being transferred TNF-$\alpha$ gene to. Conclusion : TNF-gene-transfer to NCI-H2058 and WEHI164 gave them resistance to TNF.

• Radiation Oncology Journal
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• v.27 no.3
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• pp.126-132
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• 2009

Purpose: We wanted to evaluate the prognostic factors for the pathologic N2 non-small cell lung cancer (NSCLC) patients who were treated by postoperative radiotherapy. Materials and Methods: We retrospectively reviewed 112 pN2 NSCLC patients who underwent surgery and postoperative radiotherapy (PORT) From January 1999 to February 2008. Seventy-five (67%) patients received segmentectomy or lobectomy and 37 (33%) patients received pneumonectomy. The resection margin was negative in 94 patients, and it was positive or close in 18 patients. Chemotherapy was administered to 103 (92%) patients. Nine (8%) patients received PORT alone. The median radiation dose was 54 Gy (range, 45 to 66), and the fraction size was 1.8~2 Gy. Results: The 2-year overall survival (OS) rate was 60.2% and the disease free survival (DFS) rate was 44.7% for all the patients. Univariate analysis showed that the patients with multiple-station N2 disease had significantly reduced OS and DFS (p=0.047, p=0.007) and the patients with an advanced T stage ($\geq$T3) had significantly reduced OS and DFS (p<0.001, p=0.025). A large tumor size ($\geq$5 cm) and positive lymphovascular invasion reduced the OS (p=0.035, 0.034). Using multivariate analysis, we found that multiple-station N2 disease and an advanced T stage ($\geq$T3) significantly reduced the OS and DFS. Seventy one patients (63.4%) had recurrence of disease. The patterns of failure were loco-regional in 23 (20.5%) patients, distant failure in 62 (55.4%) and combined loco-regional and distant failure in 14 (12.5%) patients. Conclusion: Multiple involvement of mediastinal nodal stations for the pN2 NSCLC patients with PORT was a poor prognostic factor in this study. A prospective study is necessary to evaluate the N2 subclassification and to optimize the adjuvant treatment.