• Title/Summary/Keyword: 방법론 평가

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A Methodology of Customer Churn Prediction based on Two-Dimensional Loyalty Segmentation (이차원 고객충성도 세그먼트 기반의 고객이탈예측 방법론)

  • Kim, Hyung Su;Hong, Seung Woo
    • Journal of Intelligence and Information Systems
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    • v.26 no.4
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    • pp.111-126
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    • 2020
  • Most industries have recently become aware of the importance of customer lifetime value as they are exposed to a competitive environment. As a result, preventing customers from churn is becoming a more important business issue than securing new customers. This is because maintaining churn customers is far more economical than securing new customers, and in fact, the acquisition cost of new customers is known to be five to six times higher than the maintenance cost of churn customers. Also, Companies that effectively prevent customer churn and improve customer retention rates are known to have a positive effect on not only increasing the company's profitability but also improving its brand image by improving customer satisfaction. Predicting customer churn, which had been conducted as a sub-research area for CRM, has recently become more important as a big data-based performance marketing theme due to the development of business machine learning technology. Until now, research on customer churn prediction has been carried out actively in such sectors as the mobile telecommunication industry, the financial industry, the distribution industry, and the game industry, which are highly competitive and urgent to manage churn. In addition, These churn prediction studies were focused on improving the performance of the churn prediction model itself, such as simply comparing the performance of various models, exploring features that are effective in forecasting departures, or developing new ensemble techniques, and were limited in terms of practical utilization because most studies considered the entire customer group as a group and developed a predictive model. As such, the main purpose of the existing related research was to improve the performance of the predictive model itself, and there was a relatively lack of research to improve the overall customer churn prediction process. In fact, customers in the business have different behavior characteristics due to heterogeneous transaction patterns, and the resulting churn rate is different, so it is unreasonable to assume the entire customer as a single customer group. Therefore, it is desirable to segment customers according to customer classification criteria, such as loyalty, and to operate an appropriate churn prediction model individually, in order to carry out effective customer churn predictions in heterogeneous industries. Of course, in some studies, there are studies in which customers are subdivided using clustering techniques and applied a churn prediction model for individual customer groups. Although this process of predicting churn can produce better predictions than a single predict model for the entire customer population, there is still room for improvement in that clustering is a mechanical, exploratory grouping technique that calculates distances based on inputs and does not reflect the strategic intent of an entity such as loyalties. This study proposes a segment-based customer departure prediction process (CCP/2DL: Customer Churn Prediction based on Two-Dimensional Loyalty segmentation) based on two-dimensional customer loyalty, assuming that successful customer churn management can be better done through improvements in the overall process than through the performance of the model itself. CCP/2DL is a series of churn prediction processes that segment two-way, quantitative and qualitative loyalty-based customer, conduct secondary grouping of customer segments according to churn patterns, and then independently apply heterogeneous churn prediction models for each churn pattern group. Performance comparisons were performed with the most commonly applied the General churn prediction process and the Clustering-based churn prediction process to assess the relative excellence of the proposed churn prediction process. The General churn prediction process used in this study refers to the process of predicting a single group of customers simply intended to be predicted as a machine learning model, using the most commonly used churn predicting method. And the Clustering-based churn prediction process is a method of first using clustering techniques to segment customers and implement a churn prediction model for each individual group. In cooperation with a global NGO, the proposed CCP/2DL performance showed better performance than other methodologies for predicting churn. This churn prediction process is not only effective in predicting churn, but can also be a strategic basis for obtaining a variety of customer observations and carrying out other related performance marketing activities.

The Clinical Significance of Bioelectrical Impedance Analysis for The Diagnosis of Obesity on Elementary Students (초등학교 아동의 비만 진단에 있어서 생체 전기저항 분석법의 의의)

  • Choi, Ki-Cheol;Ahn, Young-Jun;Yang, Eun-Seok;Park, Sang-Kee;Park, Jong;Moon, Kyung-Rye
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.1 no.1
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    • pp.107-114
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    • 1998
  • Purpose: The purpose of our study is to provide useful information for me-asurement methods of childhood obesity and to provide clinical significance of bioelectrical impedance analysis. Methods: We measured height, weight, waist to hip ratio, skinfold thickness and bioelectrical impedance from 206 elementary students in Kwangju from May to July 1997. Results: In males; 1) There were statistically high correlations between tri-ceps skinfold thickness and body mass index (BMI), percentage of body fat (%BF), weight, Rohler index (RI), total fat weight (TFW), waist to hip (W/H) ratio, height, lean body mass (LBM) (all, p<0.001). 2) There were statistically high correlations between subscapular skinfold thickness and BMI, RI, weig-ht, %BF, TBW (all, p<0.001). 3) There were statistically high correlations between %BF and BMI, triceps skinfold thickness, RI, TFW, subscapular skinfold thickness, weight (all, p<0.001). In females; 4) There were statistically high correlations between triceps skinfold thickness and BMI, weight, LBM, height, %BF (all, p<0.001). 5) There were statistically significant correlations between subscapular skinfold thickness and BMI, weight, LBM, RI, height. 6) There were statistically high correlations between percentage of body fat and BMI, RI, triceps skinfold thickness. The percentage of body fat according to the bioelectrical impedance analysis highly correlated with that calculated by skinfold thickness in males (r=0.57, p<0.01) and in females (r=0.30, p<0.01). Conclusion: The results of our study suggests that bioelectrical impedance analysis is a useful method of estimating body fat in the childhood obesity.

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Dosimetric Comparison of Three Dimensional Conformal Radiation Radiotherapy and Helical Tomotherapy Partial Breast Cancer (유방암 환자의 3D-CRT, TOMO 방법에 따른 선량 분포 평가)

  • Kim, Dae-Woong;Kim, Jong-Won;Choi, Yun-Kyeong;Kim, Jung-Soo;Hwang, Jae-Woong;Jeong, Kyeong-Sik;Choi, Gye-Suk
    • The Journal of Korean Society for Radiation Therapy
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    • v.20 no.1
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    • pp.11-15
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    • 2008
  • Purpose: The goal of radiation treatment is to deliver a prescribed radiation dose to the target volume accurately while minimizing dose to normal tissues. In this paper, we comparing the dose distribution between three dimensional conformal radiation radiotherapy (3D-CRT) and helical tomotherapy (TOMO) plan for partial breast cancer. Materials and Methods: Twenty patients were included in the study, and plans for two techniques were developed for each patient (left breast:10 patients, right breast:10 patients). For each patient 3D-CRT planning was using pinnacle planning system, inverse plan was made using Tomotherapy Hi-Art system and using the same targets and optimization goals. We comparing the Homogeneity index (HI), Conformity index (CI) and sparing of the organs at risk for dose-volume histogram. Results: Whereas the HI, CI of TOMO was significantly better than the other, 3D-CRT was observed to have significantly poorer HI, CI. The percentage ipsilateral non-PTV breast volume that was delivered 50% of the prescribed dose was 3D-CRT (mean: 40.4%), TOMO (mean: 18.3%). The average ipsilateral lung volume percentage receiving 20% of the PD was 3D-CRT (mean: 4.8%), TOMO (mean: 14.2), concerning the average heart volume receiving 20% and 10% of the PD during treatment of left breast cancer 3D-CRT (mean: 1.6%, 3.0%), TOMO (mean: 9.7%, 26.3%) Conclusion: In summary, 3D-CRT and TOMO techniques were found to have acceptable PTV coverage in our study. However, in TOMO, high conformity to the PTV and effective breast tissue sparing was achieved at the expense of considerable dose exposure to the lung and heart.

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Evaluation of the Usefulness of Exactrac in Image-guided Radiation Therapy for Head and Neck Cancer (두경부암의 영상유도방사선치료에서 ExacTrac의 유용성 평가)

  • Baek, Min Gyu;Kim, Min Woo;Ha, Se Min;Chae, Jong Pyo;Jo, Guang Sub;Lee, Sang Bong
    • The Journal of Korean Society for Radiation Therapy
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    • v.32
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    • pp.7-15
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    • 2020
  • Purpose: In modern radiotherapy technology, several methods of image guided radiation therapy (IGRT) are used to deliver accurate doses to tumor target locations and normal organs, including CBCT (Cone Beam Computed Tomography) and other devices, ExacTrac System, other than CBCT equipped with linear accelerators. In previous studies comparing the two systems, positional errors were analysed rearwards using Offline-view or evaluated only with a Yaw rotation with the X, Y, and Z axes. In this study, when using CBCT and ExacTrac to perform 6 Degree of the Freedom(DoF) Online IGRT in a treatment center with two equipment, the difference between the set-up calibration values seen in each system, the time taken for patient set-up, and the radiation usefulness of the imaging device is evaluated. Materials and Methods: In order to evaluate the difference between mobile calibrations and exposure radiation dose, the glass dosimetry and Rando Phantom were used for 11 cancer patients with head circumference from March to October 2017 in order to assess the difference between mobile calibrations and the time taken from Set-up to shortly before IGRT. CBCT and ExacTrac System were used for IGRT of all patients. An average of 10 CBCT and ExacTrac images were obtained per patient during the total treatment period, and the difference in 6D Online Automation values between the two systems was calculated within the ROI setting. In this case, the area of interest designation in the image obtained from CBCT was fixed to the same anatomical structure as the image obtained through ExacTrac. The difference in positional values for the six axes (SI, AP, LR; Rotation group: Pitch, Roll, Rtn) between the two systems, the total time taken from patient set-up to just before IGRT, and exposure dose were measured and compared respectively with the RandoPhantom. Results: the set-up error in the phantom and patient was less than 1mm in the translation group and less than 1.5° in the rotation group, and the RMS values of all axes except the Rtn value were less than 1mm and 1°. The time taken to correct the set-up error in each system was an average of 256±47.6sec for IGRT using CBCT and 84±3.5sec for ExacTrac, respectively. Radiation exposure dose by IGRT per treatment was measured at 37 times higher than ExacTrac in CBCT and ExacTrac at 2.468mGy and 0.066mGy at Oral Mucosa among the 7 measurement locations in the head and neck area. Conclusion: Through 6D online automatic positioning between the CBCT and ExacTrac systems, the set-up error was found to be less than 1mm, 1.02°, including the patient's movement (random error), as well as the systematic error of the two systems. This error range is considered to be reasonable when considering that the PTV Margin is 3mm during the head and neck IMRT treatment in the present study. However, considering the changes in target and risk organs due to changes in patient weight during the treatment period, it is considered to be appropriately used in combination with CBCT.

Evaluation of dose delivery accuracy due to variation in pitch and roll (세기변조방사선치료에서 Pitch와 Roll 변화에 따른 선량전달 정확성 평가)

  • Jeong, Chang Young;Bae, Sun Myung;Lee, Dong Hyung;Min, Soon Ki;Kang, Tae Young;Baek, Geum Mun
    • The Journal of Korean Society for Radiation Therapy
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    • v.26 no.2
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    • pp.239-245
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    • 2014
  • Purpose : The purpose of this study is to verify the accuracy of dose delivery according to the pitch and roll rotational setup error with 6D robotic couch in Intensity Modulated Radiation Therapy (IMRT) for pelvic region in patients. Materials and Methods : Trilogy(Varian, USA) and 6D robotic couch(ProturaTM 1.4, CIVCO, USA) were used to measure and analyze the rotational setup error of 14 patients (157 setup cases) for pelvic region. The total 157 Images(CBCT 78, Radiography 79) were used to calculate the mean value and the incidence of pitch and roll rotational setup error with Microsoft Office Excel 2007. The measured data (3 mm, 3%) at the reference angle ($0^{\circ}$) without couch rotation of pitch and roll direction was compared to the others at different pitch and roll angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) to verify the accuracy of dose delivery by using 2D array ionization chamber (I'mRT Matrixx, IBA Dosimetry, Germany) and MultiCube Phantom(IBA Dosimetry, Germany). Result from the data, gamma index was evaluated. Results : The mean values of pitch and roll rotational setup error were $0.9^{\circ}{\pm}0.7$, $0.5^{\circ}{\pm}0.6$. The maximum values of them were $2.8^{\circ}$, $2.0^{\circ}$. All of the minimum values were zero. The mean values of gamma pass rate at four different pitch angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) were 97.75%, 96.65%, 94.38% and 90.91%. The mean values of gamma pass rate at four different roll angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) were 93.68%, 93.05%, 87.77% and 84.96%. when the same angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$) of pitch and roll were applied simultaneously, The mean values of each angle were 94.90%, 92.37% and 87.88%, respectively. Conclusion : As a result of this study, it was able to recognize that the accuracy of dose delivered is lowered gradually as pitch and roll increases. In order to increase the accuracy of delivered dose, therefore, it is recommended to perform IGRT or correct patient's position in the pitch and roll direction, to improve the quality of treatment.

Evaluation of the reconstruction of image acquired from CT simulator to reduce metal artifact (Metal artifact 감소를 위한 CT simulator 영상 재구성의 유용성 평가)

  • Choi, Ji Hun;Park, Jin Hong;Choi, Byung Don;Won, Hui Su;Chang, Nam Jun;Goo, Jang Hyun;Hong, Joo Wan
    • The Journal of Korean Society for Radiation Therapy
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    • v.26 no.2
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    • pp.191-197
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    • 2014
  • Purpose : This study presents the usefulness assessment of metal artifact reduction for orthopedic implants(O-MAR) to decrease metal artifacts from materials with high density when acquired CT images. Materials and Methods : By CT simulator, original CT images were acquired from Gammex and Rando phantom and those phantoms inserted with high density materials were scanned for other CT images with metal artifacts and then O-MAR was applied to those images, respectively. To evaluate CT images using Gammex phantom, 5 regions of interest(ROIs) were placed at 5 organs and 3 ROIs were set up at points affected by artifacts. The averages of standard deviation(SD) and CT numbers were compared with a plan using original image. For assessment of variations in dose of tissue around materials with high density, the volume of a cylindrical shape was designed at 3 places in images acquired from Rando phantom by Eclipse. With 6 MV, 7-fields, $15{\time}15cm2$ and 100 cGy per fraction, treatment planning was created and the mean dose were compared with a plan using original image. Results : In the test with the Gammex phantom, CT numbers had a few difference at established points and especially 3 points affected by artifacts had most of the same figures. In the case of O-MAR image, the more reduction in SD appeared at all of 8 points than non O-MAR image. In the test using the Rando Phantom, the variations in dose of tissue around high density materials had a few difference between original CT image and CT image with O-MAR. Conclusion : The CT images using O-MAR were acquired clearly at the boundary of tissue around high density materials and applying O-MAR was useful for correcting CT numbers.

The evaluation for the usability ofthe Varian Standard Couch modelingusing Treatment Planning System (치료계획 시스템을 이용한 Varian Standard Couch 모델링의 유용성 평가)

  • Yang, yong mo;Song, yong min;Kim, jin man;Choi, ji min;Choi, byeung gi
    • The Journal of Korean Society for Radiation Therapy
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    • v.28 no.1
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    • pp.77-86
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    • 2016
  • Purpose : When a radiation treatment, there is an attenuation by Carbon Fiber Couch. In this study, we tried to evaluate the usability of the Varian Standard Couch(VSC) by modeling with Treatment Planning System (TPS) Materials and Methods : VSC was scanned by CBCT(Cone Beam Computed Tomography) of the Linac(Clinac IX, VARIAN, USA), following the three conditions of VSC, Side Rail OutGrid(SROG), Side Rail InGrid(SRIG), Side Rail In OutSpine Down Bar(SRIOS). After scan, the data was transferred to TPS and modeled by contouring Side Rail, Side Bar Upper, Side Bar Lower, Spine Down Bar automatically. We scanned the Cheese Phantom(Middelton, USA) using Computed Tomography(Light Speed RT 16, GE, USA) and transfer the data to TPS, and apply VSC modeled previously with TPS to it. Dose was measured at the isocenter of Ion Chamber(A1SL, Standard imaging, USA) in Cheese Phantom using 4 and 10 MV radiation for every $5^{\circ}$ gantry angle in a different filed size($3{\times}3cm^2$, $10{\times}10cm^2$) without any change of MU(=100), and then we compared the calculated dose and measured dose. Also we included dose at the $127^{\circ}$ in SRIG to compare the attenuation by Side Bar Upper. Results : The density of VSC by CBCT in TPS was $0.9g/cm^3$, and in the case of Spine Down Bar, it was $0.7g/cm^3$. The radiation was attenuated by 17.49%, 16.49%, 8.54%, and 7.59% at the Side Rail, Side Bar Upper, Side Bar Lower, and Spine Down Bar. For the accuracy of modeling, calculated dose and measured dose were compared. The average error was 1.13% and the maximum error was 1.98% at the $170^{\circ}beam$ crossing the Spine Down Bar. Conclusion : To evaluate the usability for the VSC modeled by TPS, the maximum error was 1.98% as a result of compassion between calculated dose and measured dose. We found out that VSC modeling helped expect the dose, so we think that it will be helpful for the more accurate treatment.

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Effectiveness of Fentanyl Transdermal Patch (Fentanyl-TTS, $Durogegic^{(R)}$) for Radiotherapy Induced Pain and Cancer Pain: Multi-center Trial (방사선치료로 인한 통증 및 암성통증에 대한 듀로제식의 효과: 다기관연구)

  • Shin, Seong-Soo;Choi, Eun-Kyung;Kim, Jong-Hoon;Ahn, Seung-Do;Lee, Sang-Wook;Kim, Yeun-Sil;Lee, Kyu-Chan;Lee, Chang-Geol;Loh, John-JK;Chun, Mi-Son;Oh, Young-Teak;Kim, Ok-Bae;Huh, Seung-Jae
    • Radiation Oncology Journal
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    • v.24 no.4
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    • pp.263-271
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    • 2006
  • $\underline{Purpose}$: To evaluate the effectiveness and safety of fentanyl-TTS in the management of radiotherapy induced acute pain and cancer pain treated with radiotherapy. $\underline{Materials\;and\;Methods}$: Our study was open labelled prospective phase IV multi-center study. the study population included patients with more 4 numeric rating scale(NRS) score pain although managed with other analgesics or more than 6 NRS score pain without analgesics. Patients divided into two groups; patients with radiotherapy induced pain (Group A) and patients with cancer pain treated with radiotherapy (Group B). All patients received 25 ug/hr of fentanyl transdermal patch. Primary end point was pain relief; second end points were change in patient quality of life, a degree of satisfaction for patients and clinician, side effects. $\underline{Results}$: Between March 2005 and June 2005, 312 patients from 26 participating institutes were registered, but 249 patients completed this study. Total number of patients in each group was 185 in Group A, 64 in Group B. Mean age was 60 years and male to female ratio was 76:24. Severe pain NRS score at 2 weeks after the application of fentanyl was decreased from 7.03 to 4.01, p=0.003. There was a significant improvement in insomnia, social functioning, and quality of life. A degree of satisfaction for patients and clinician was very high. The most common reasons of patients' satisfactions was good pain control. Ninety six patients reported side effect. Nausea was the most common side effect. There was no serious side effect. $\underline{Conclusion}$: Fentanyl-TTS was effective in both relieving pain with good tolerability and improving the quality of life for patients with radiotherapy induced acute pain and cancer pain treated with radiotherapy. The satisfaction of the patients and doctors was good. There was no major side effect.

Evaluation of the accuracy of the HexaPOD evo RT system using Non-coplanar beams in lung cancer (폐암환자의 비동일평면 선속 빔 치료 시 HexaPOD evo RT system 의 정확성 평가)

  • Jang, Sewuk;cho, Kangchul;Lee, Sangkyoo;Kim, Jooho;Cho, Jeonghee
    • The Journal of Korean Society for Radiation Therapy
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    • v.27 no.2
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    • pp.115-122
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    • 2015
  • Purpose : The aim of this study, evaluate the accuracy of HeaxPOD evo RT system using the non-coplanar beam. Materials and Methods : 13 treatment plans are used which applied non-coplanar beams and 10 treatment plans which coplanar beams are used. the correction value what adjust to 6D couch is determined by each patient's setup errors only rotation direction. The study executed followings. first, Applying the correction value, measure the point dose and calculate the ${\gamma}$-index(${\gamma}=3%$ / 3 mm, ${\gamma}=2%$ / 2 mm). second, acquire data as previous methods without correction by HexaPOD. Results : For comparing the two results, we find out the more precise applying HexaPOD by point dose 0.2% in coplanar and non-coplanar. in the case of ${\gamma}$-index<1(${\gamma}=3%$ / 3 mm), more precise 2.2% in coplanar and 7% in Non-coplanar. Particularly, ${\gamma}$-index<1(2% / 2 mm) show the difference 9.2% in coplanar and 15.1% non-coplanar between apply HexaPOD and dose not apply HexaPOD. Conclusion : Using the HexaPOD is more precise than without HexaPOD. It suggests that HexaPOD evo RT system is very useful for precise and high dose delivery.

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Evaluation of the Breast plan using the TLD and Mosfet for the skin dose (열형광선량계(TLD)와 MOSFET을 이용한 유방암 방사선치료계획에 대한 피부선량 평가)

  • Kim, seon myeong;Kim, young bum;Bak, sang yun;Lee, sang rok;Jeong, se young
    • The Journal of Korean Society for Radiation Therapy
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    • v.27 no.2
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    • pp.107-113
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    • 2015
  • Purpose : The measurement of skin dose is very important that treatment of breast cancer. On account of the cold or hot dose as compared with prescription dose, it is necessary to analyse the skin dose occurring during the various plan of the breast cancer treatment. At our hospital, we want to apply various analyses using a diversity of dosimeters to the breast cancer treatment. Subjectss and Methods : In the study, the anthropomorphic phantom is used to find out the dose difference of the skin(draining site), scar and others occurring from the tangential treatment plan of breast cancer. We took computed tomography scan of the anthropomorphic phantom and made plans for the treatment planing using open and wedge, Field-in-Field, Dose fluence. Using these, we made a comparative analysis of the dose date points by using the Eclipse. For the dose comparison, we place the anthropomorphic phantom in the treatment room and compared the measurement results by using the TLD and MOSFET on the dose data points. Results : On the central point of treatment planing basis, the upward and downward skin dose measured by the MOSFET was the highest when the fluence was used. The skin dose of inner and outer was distinguished from the figure(5.7% ~ 10.3%) when the measurements were fulfilled by using TLD and MOSFET. The other side of breast dose was the lowest in the open beam, on the other hand, is highest in the Dose fluence plan. In the different kinds of treatment, the dose deviation of inner and outer was the highest, and so this was the same with the TLD and MOSFET measurement case. The outer deviation was highest in the TLD, and the Inner'was highest in the MOSFET. Conclusion : Skin dose in relation to the treatment plan was the highest in the planing using the fluence technique in general and it was supposed that the high dose had been caused by the movement of the MLC. There's some differences among the all the treatment planning, but the sites such as IM node occurring the lack of dose, scar, drain site are needed pay close attention. Using the treatment planning of dose fluence is good to compensate the lack of dose, but It increases the dose of the selective range rather than the overall dose. Therefore, choosing the radiotherapy technique is desirable in the lights of the age and performance of the patient.

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