• 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.15 no.4
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• pp.393-402
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• 1997

Purpose : When an x-ray beam of small field size is irradiated to target area containing an air cavity, such as larynx, the underdosing effect is observed in the region near the interfaces of air and soft tissue. With a larynx model, air cavity embedded in tissue-equivalent material, this study is intonded for examining Parameters, such as beam quality, field size, and cavity size, to affect the dose distribution near the air cavity. Materials and Methods : Three x-rar beams, 4-, 6- and 10-MV, were employed to Perform a measurement using a 2cm $(width){\times}L$ (length in cm, one side of x-ray field used 2cm (height) air cavity in the simulated larynx. A thin window parallel-plate chamber connected to an electrometer was used for a dosimetry system. A ratio of the dose at various distances from the cavity-tissue interface to the dose at the same points in a homogeneous Phantom (ebservedlexpected ratio, O/E) normalized buildup curves, and ratio of distal surface dose to dose at the maximum buildup depth were examined for various field sizes. Measurement for cavity size effect was performed by varying the height (Z) of the air cavity with the width kept constant for several field sizes. Results : No underdosing effect for 4-MV beam for fields larger than $5cm\times5cm$ was found For both 6- and 10-MV beams, the underdosing portion of the larynx at the distal surface was seen to occur for small fields, $4cm\times4cm\;and\;5cm\times5cm$. The underdosed tissue was increased in its volume with beam energy even for similar surface doses. The relative distal surface dose to maximum dose was changed to 0.99 from 0.95, 0.92, and 0.91 for 4-, 6-, and 10-MV, respectively, with increasing field size, $4cm\times4cm\;to\;8cm\times8cm$, For 6- and 10-MV beams, the dose at the surface of the cavity is measured less than the predicted by about two and three percent. respectively. but decrease was found for 4-MV beam for $5cm\times5cm$ field. For the $4cm\timesL\timesZ$ (height in cm). varying depth from 0.0 to 4.8cm, cavity, O/E> 1.0 was observed regardless of the cavity size for any field larger than about $8cm\times8cm$. Conclusion : The magnitude of underdosing depends on beam energy, field size. and cavity size for the larynx model. Based on the result of the study. caution must be used when a small field of a high quality x-ray beam is irradiated to regions including air cavities. and especially the region where the tumor extends to the surface. Low quality beam. such as. 4-MV x-ray, and larger fields can be used preferably to reduce the risk of underdosing, local failure. In the case of high quality beams such as 6- and 10-MV x-rays, however. an additional boost field is recommended to add for the compensation of the underdosing region when a typically used treatment field. $8cm\times8cm$, is employed.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.1
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• pp.47-55
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• 2016

To evaluate the position accuracy of the MLC. This study analyzed the variations of the dosimetric leaf gap(DLG) and MLC transmission factor to reflect the location of the MLC leaves according to the dose rate variation for dynamic IMRT. We used the 6 MV and 10 MV X-ray beams from linear accelerator with a Millennium 120 MLC system. We measured the variation of DLG and MLC transmission factor at depth of 10 cm for the water phantom by varying the dose rate to 200, 300, 400, 500 and 600 MU/min using the CC13 and FC-65G chambers. For 6 MV X-ray beam, a result of measuring based on a dose rate 400 MU/min by varying the dose rate to 200, 300, 400, 500 and 600 MU/min of the difference rate was respectively -2.59, -1.89, 0.00, -0.58, -2.89%. For 10 MV X-ray beam, the difference rate was respectively ?2.52, -1.69, 0.00, +1.28, -1.98%. The difference rate of MLC transmission factor was in the range of about ${\pm}1%$ of the measured values at the two types of energy and all of the dose rates. This study evaluated the variation of DLG and MLC transmission factor for the dose rate variation for dynamic IMRT. The difference of the MLC transmission factor according to the dose rate variation is negligible, but, the difference of the DLG was found to be large. Therefore, when randomly changing the dose rate dynamic IMRT, it may significantly affect the dose delivered to the tumor. Unless you change the dose rate during dynamic IMRT, it is thought that is to be the more accurate radiation therapy.

• Journal of Gastric Cancer
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• v.6 no.2
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• pp.76-83
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• 2006

Purpose: Endoscopic incision and submucosal dissection (EISD) is a technique that is being implemented for the resection of gastric adenomas and early gastric cancer (EGC). Since EISD requires a high degree of skill and experience, and due to its association with a moderate risk of gastrointestinal bleeding, its use has been limited. The objective of this study is to investigate the clinical benefits of EISD based upon clinical data on the EISD procedure. Materials and Methods: This study was conducted at Soonchunhyang University Hospital and it included 179 gastric adenoma and early gastric carcinoma lesions from 164 patients who had undergone an EISD from February 2003 to May 2005. Results: Among the total of 179 lesions, the distributions of EGC and adenomas were 70.3% (126/179) and 23.4% (42/179) respectively. The sizes of lesions were divided into 10 mm or less, $11{\sim}20\;mm,\;21{\sim}30\;mm$ and greater than 31 mm and each rates are 10.0% (18/179), 46.3% (83/179), 30% (50/179) and 15.0% (28/179). Among 120 cases which could be measured depth of lesion in according to pathologic findings, m1 (0.8%, 1/120), m2 (38.3%, 46/120), m3 (25%, 57/120), sm1 (11.7%, 14/120), sm2 (1.6%, 2/120) were diagnosed as early stages of gastric cancer. The complete resection rate was 85.2% (150/176) and en-bloc resection rate was 96.0% (169/176). Complications as such as perforation and bleeding developed in 4.4%(8/179) and 21.2% (38/179), respectively. Conclusion: EISD is an effective in the endoscopic treatment for gastric adenoma and early gastric cancers. However, further evaluation of this method and long-term follow-up will be necessary for an evaluation of the recurrence rate after resection of a tumor.

• Journal of Gastric Cancer
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• v.7 no.4
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• pp.213-218
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• 2007

Purpose: Laparoscopy-assisted distal gastrectomy (LADG) is gaining wider acceptance for the treatment of early gastric cancer. However, firm evidence supporting the long-term outcome after LADG for gastric cancer is unknown. This study compared long-term quality of life after LADG versus an open distal gastrectomy (ODG) for early gastric cancer. Methods: This study included 29 patients who underwent LADG and 57 patients who underwent ODG for the treatment of stage I gastric cancer. Quality of life was evaluated based on the Korean version of EORTC QLQ-C30 (version 3.0) and EORTC QLQ-STO22 one year after surgery. All patients underwent a Billroth II gastrectomy for stage I gastric cancer between January 2003 and December 2004. Results: A total of 86 (58%) out of 154 patients responded to the questionnaire. Demographic features showed no difference between the two groups of patients for age, sex, depth of invasion, lymph node metastasis except for tumor size and the number of retrieved lymph nodes. The mean score for global health status was not statistically different (LADG, $60.3{\pm}20.4$ vs ODG, $57{\pm}20.6$; P=0.413). The total score of 21 items related to stomach cancer (EORTC QLQ-STO22) also was not statistically different (LADG, $68.9{\pm}64.9$ vs ODG, $94.5{\pm}97.3$; P=0.340). Conclusion: Based on the results of the Korean version of EORTC QLQ-C 30 (version 3.0) and EORTC. QLQ-STO22, LADG does not seem to have any long-term benefit over ODG on 'quality of life'.

• Radiation Oncology Journal
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• v.13 no.4
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• pp.377-383
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• 1995

Purpose : To obtain the optimal treatement method in patients with endometrial carcinoma(clinical stage FIGO I, II) by comparative analysis between preoperative radiotherapy (pre-op RT) and postoperative radiotherapy (post-op RT). Material and Methods : A retrospective review of 62 endometrial carcinoma patients referred to the Yonsei Cancer Center for radiotherapy between 1985 and 1991 was undertaken. Of 62 patients, 19 patients(Stagel : 12 patients. Stagell;7 patients) received pre-op RT before TAH(Total Abdominal Hysterectomy) and BSO (Bilateral Salphingoophorectomy) (Group 1) and 43 patients(Stage 1;32 patients, Stage 2; 11 patients) received post-op RT after TAH and BSO (Group 2). Pre-op irradiation was given 4-6 weeks prior to surgery and post-op RT administered on 4-5 weeks following surgery. All patients except 1 patient(Group 2: ICR alone) received external irradiation. Seventy percent(13/19) of pre-op RT group and 54 percent(23/42) of post-op RT group received external pelvic irradiation and intracavitary radiation therapy(ICR). External radiation dose was 39.6-55 Gy(median 45 Gy) in 5-6. 5weeks through opposed AP/PA fields or 4-field box technique treating daily, five days per week, 180 cGy per fraction. ICR doses were prescribed to point A(20-39.6 Gy, median 39 Gy) in Group 1 and 0.5cm depth from vaginal surface (18-30 Gy,median 21 Gy) in Group 2. Results : The overall 5 year survival rate was $95{\%}$. No survival difference between pre-op and post-op RT group.($89.3{\%}$ vs $97.7{\%}$, p>0.1) There was no survival difference by stage, grade and histology between two groups. The survival rate was not affected by presence of residual tumor of surgical specimen after pre-op RT in Group 1 (p>0.1), but affected by presence of lymph node metastasis in post-op RT group(P<0.5). The complication rate of pre-op RT group was higher than post-op RT. ($16{\%}$ vs $5{\%}$) Conclusion : Post-op radiotherapy offers the advantages of accurate surgical-pathological staging and low complication rate.

• Journal of Gastric Cancer
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• v.5 no.1
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• pp.29-33
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• 2005

Purpose: To determine the prognostic values of the hematologic parameters checked preoperatively in gastric cancer patients, we evaluated and compared the relationship between hematologic parameters and clinicopathologic factors of gastric cancer patient. Materials and Methods: The medical records of 357 consecutive patients who had undergone surgery for gastric cancer at the Department of Surgery, Hanyang University Hospital, between Dec. 2,000 and Dec. 2003 were reviewed. To exclude any adverse effect of invasive procedures to hematologic parameters, the samples taken immediately at outpatient department was used. The normal range of serum albumin was defined above 3.5 g/dl, serum hemoglobin above 12 g/dl, and serum platelet count under $400\times10^{3}{\mu}l$. Patients were defined as group 1 when any of these parameters was abnormal, and defined as group 2 when all parameters were normal. The relationships between hematologic parameters and survival rate were investigated. Results: The mean values of platelet count increased, but level of serum albumin and serum hemoglobin decreased significantly according to the advancement of the disease stage (P=0.000). The differences of depth of tumor invasion and lymph node metastasis between the group 1 and the group2 was statistically significant (P=0.001). Three-year survival difference between group 1 and group 2 was significant (P=0.037). Conclusion: The hematologic parameters checked preoperatively in patients of gastric cancer are simple and cheap, meanwhile reflect the general condition of the patients. Any presence of anemia, hypoalbuminemia, or thrombocytosis can predict the progression of the disease and poor survival rates.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.68-76
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• 1998

Background: Patients with centrally recurred bronchogenic carcinoma make a complaint of many symptoms like hemoptysis, cough & dyspnea. At these conditions, the goal of treatment is only to relieve their symptoms. High dose rate brachytherapy(HDR-BT) is the palliative treatment modality of centrally located endobronchial tumor regardless of previous external irradiation(XRT) on the same site in symptomatic patients. Methods: We studied the effects of HDR-BT in 26 patients with symptomatic recurrent lung cancer. Patients(male: 24, mean age: 54yrs)were treated with HDR-BT underwent bronchoscopic placement of $^{192}Ir$ HDR after loading unit(Gammamed$^{(T)}$, Germany) to deliver 500cGY intraluminal irradiation at a depth of 1cm every lwk on 3 occasions. Evaluation at base line and 4wks after HDR brachytherapy included chest X-ray, bronchscopy, symptoms (Standadized Scale for dyspnea,cough,hemoptysis), and Karnofsky performance scale. Results: Endobronchial obstruction was improved in 11/26 patients(37%). Atelectasis in chest X-ray was improved in 5/15 patients(33%). Hemoptysis, dyspnea & cough were improved in 5/10 patients (50%), 5/8 patients (62%) & 10/18 patients (56%) respectively. Karnofsky performance status was changed from 76.4 scores in pretreatment to 77.6 scores after treatment. During HDR-BT, massive hemoptysis (2 patients) and pneumothorax(1 patient) were occurred as complications. Conclusion: We concluded that HDR-BT gave additional benefits for the control of symptoms and general performance and endobronchial obstruction & atelectasis. And HDR-BT will be an additional treatment for the recurrent and endobronchial obstructive lung cancer.

• BMB Reports
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• v.57 no.2
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• pp.110-115
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• 2024

Alterations in DNA methylation play an important pathophysiological role in the development and progression of colorectal cancer. We comprehensively profiled DNA methylation alterations in 165 Korean patients with colorectal cancer (CRC), and conducted an in-depth investigation of cancer-specific methylation patterns. Our analysis of the tumor samples revealed a significant presence of hypomethylated probes, primarily within the gene body regions; few hypermethylated sites were observed, which were mostly enriched in promoter-like and CpG island regions. The CpG Island Methylator Phenotype-High (CIMP-H) exhibited notable enrichment of microsatellite instability-high (MSI-H). Additionally, our findings indicated a significant correlation between methylation of the MLH1 gene and MSI-H status. Furthermore, we found that the CIMP-H had a higher tendency to affect the right-side of the colon tissues and was slightly more prevalent among older patients. Through our methylome profile analysis, we successfully verified the methylation patterns and clinical characteristics of Korean patients with CRC. This valuable dataset lays a strong foundation for exploring novel molecular insights and potential therapeutic targets for the treatment of CRC.

• Journal of Gastric Cancer
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• v.5 no.2
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• pp.89-94
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• 2005

Purpose: Early gastric cancer (EGC) has an excellent prognosis compared to advanced gastric cancer. The 5-year survival rate for EGC now exceeds $90\%$, and EGC is recognized as a curable malignancy. The important prognostic factor in EGC is the status of lymph-node metastasis. Despite conserving surgery being suggested for EGC at present, it is of vital importance to select a surgical method appropriate to each individual case. This retrospective study was undertaken to clarify clinicopathologic features and factors related to lymph-node metastasis in submucosal gastric cancer in order to determine an appropriate therapy. Materials and Methods: This study analyzed the clinicopathologic features for 279 patients with a submucosal gastric carcinoma (Group I) and compared with those of patients with mucosal (Group II) or muscularis proprial gastric carcinoma (Group III). All patients were operated on from 1981 to 1999 at Chonnam University Hospital. There were no statistically significant differences among the groups with respect to age, gender, tumor location, hepatic metastasis, or peritoneal dissemination. Results: Positive lymph node metastasis was found in 47 ($16.8\%$) of the 279 patients with a submucosal gastric carcinoma. The incidence of lymph-node metastasis was significantly higher in patients with a submucosal gastric carcinoma than in patients with a mucosal gastric carcinoma ($16.8\%\;vs.\;3.9\%\;$; P<0.01). Therefore, depth of invasion was a significant factor affecting in lymph-node metastasis. The 5-year survival rates were $88.6\%$ for patients in Group I, $95.2\%$ for patients in Group II, and $72.7\%$ for patients in Group III (P<0.01 for Group I vs. Group II; Group I vs. Group III). In patients with a submucosal gastric carcinoma, the survival rate with positive lymph nodes was significantly poorer than that of patients without lymph-node metastasis ($87.3\%\;vs.\;94.2\%$; P<0.01). Conclusion: Gastrectomy with D2 lymph node dissection is an appropriate operative procedure for patients with a submucosal gastric carcinoma.