• Asian Pacific Journal of Cancer Prevention
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• 제16권5호
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• pp.1687-1692
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• 2015

Nasopharyngeal carcinoma is an endemic disease within specific regions in the world. Radiotherapy is the main treatment. In recent decades, intensity-modulated radiation therapy has undergone a rapid evolution. Compared with two-dimensional radiotherapy and/or three-dimensional conformal radiotherapy, evidence has shown it may improve quality of life and prognosis for patients with nasopharyngeal carcinoma. In addition, helical tomotherapy is an emerging technology of intensity-modulated radiation therapy. Its superiority in dosimetric and clinical outcomes has been demonstrated when compared to traditional intensity-modulated radiation therapy. However, many challenges need to be overcome for intensity-modulated radiation therapy of nasopharyngeal carcinoma in the future. Issues such as the status of concurrent chemotherapy, updating of target delineation, the role of replanning during IMRT, the causes of the main local failure pattern require settlement. The present study reviews traditional intensity-modulated radiation therapy, helical tomotherapy, and new challenges in the management of nasopharyngeal carcinoma.

• Radiation Oncology Journal
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• 제37권4호
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• pp.279-285
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• 2019

Purpose: This study was conducted to compare the outcome of three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) for the postoperative treatment of biliary tract cancer. Materials and Methods: From February 2008 to June 2016, 57 patients of biliary tract cancer treated with curative surgery followed by postoperative 3D-CRT (n = 27) or IMRT (n = 30) were retrospectively enrolled. Results: Median follow-up time was 23.6 months (range, 5.2 to 97.6 months) for all patients and 38.4 months (range, 27.0 to 89.2 months) for survivors. Two-year recurrence-free survival is higher in IMRT arm than 3D-CRT arm with a marginal significance (25.9% vs. 47.4%; p = 0.088). Locoregional recurrence-free survival (64.3% vs. 81.7%; p = 0.122) and distant metastasis-free survival (40.3% vs. 55.8%; p = 0.234) at two years did not show any statistical difference between two radiation modalities. In the multivariate analysis, extrahepatic cholangiocarcinoma, poorly-differentiated histologic grade, and higher stage were significant poor prognostic factors for survival. Severe treatment-related toxicity was not significantly different between two arms. Conclusions: IMRT showed comparable results with 3D-CRT in terms of recurrence, and survival, and radiotherapy toxicity for the postoperative treatment of biliary tract cancer.

• 한국의학물리학회지:의학물리
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• 제32권4호
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• pp.172-178
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• 2021

Purpose: This study aimed to develop a deep learning architecture combining two task models to generate synthetic computed tomography (sCT) images from low-tesla magnetic resonance (MR) images to improve metallic marker visibility. Methods: Twenty-three patients with cervical cancer treated with intracavitary radiotherapy (ICR) were retrospectively enrolled, and images were acquired using both a computed tomography (CT) scanner and a low-tesla MR machine. The CT images were aligned to the corresponding MR images using a deformable registration, and the metallic dummy source markers were delineated using threshold-based segmentation followed by manual modification. The deformed CT (dCT), MR, and segmentation mask pairs were used for training and testing. The sCT generation model has a cascaded three-dimensional (3D) U-Net-based architecture that converts MR images to CT images and segments the metallic marker. The performance of the model was evaluated with intensity-based comparison metrics. Results: The proposed model with segmentation loss outperformed the 3D U-Net in terms of errors between the sCT and dCT. The structural similarity score difference was not significant. Conclusions: Our study shows the two-task-based deep learning models for generating the sCT images using low-tesla MR images for 3D ICR. This approach will be useful to the MR-only workflow in high-dose-rate brachytherapy.

• Asian Pacific Journal of Cancer Prevention
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• 제14권4호
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• pp.2663-2665
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• 2013

Objective: To compare the efficacy and complications of chemotherapy and late course three-dimensional conformal radiotherapy (3DCRT) in treating patients with stage III non-small cell lung cancer (NSCLC). Patients and Methods: All patients were divided into two groups: to receive chemotherapy and late course 3DCRT (3DCRT group), or chemotherapy and conventional fraction radiation (control group). In the 3DCRT-group, patients were given 6~15 MV X-rays with a total dose of 40 Gy, followed by 3DCRT, 2.5 Gy~3.0 Gy per fraction, 1 fraction/every day, total 68 Gy~70 Gy; in the control group, with conventional fraction radiation the total dose was 64~66 Gy. The chemotherapy regimen in both cases was EP (VP-16 and DDP). Results: Sixty four patients with stage III NSCLC were divided into two groups: 32 patients into 3DCRT, 32 into the control group. One and 2-year survival rates in 3DCRT and control group were 87.5%, 56.3%mad 65.6%, 34.4%, respectively (P<0.05); local control rates were 90.6%, 81.3% and 65.6%, 53.1%, respectively (P<0.05). Conclusion: Chemotherapy and late course 3DCRT is associated with improved survival rate in patients with stage III NSCLC with good tolerability.

• Asian Pacific Journal of Cancer Prevention
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• 제16권5호
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• pp.1743-1745
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• 2015

Objective: To evaluate the efficacy and adverse effects of three dimensional conformal radiotherapy (3D-CRT) with tamoxifen in treating patients with postoperative malignant glioma. Patients and Methods: 60 patients of postoperative malignant glioma were randomly assigned into two groups, 30 patients were treated with 3D-CRT plus tamoxifen (treatment group), and the other 30 patients with 3D-CRT plus temozolomide (control group). All patients were radiated by 6MV X-ray, 2.0Gy per fraction, once daily, with a total dose (DT) of 56~60Gy. Tamoxifen was delivered at $60mg/m^2/d$, temozolomide was given at $75mg/m^2/d$. All patients were treated with concurrent radiotherapy. Results: One, 2, 3 year survival rates of treatment and control group were 63.3%, 30.0%, 23.0% and 70.0%, 33.3%, 26.7%, respectively (${\chi}^2=0.01$, 0.23, 0.09, P>0.05). The rate of thromboembolism in treatment group was 6.7%. Conclusion: Therapeutic efficacy of two groups was similar, but it was more cost-effective in treatment group, and toxicity did not increase.

• Asian Pacific Journal of Cancer Prevention
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• 제17권11호
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• pp.4935-4937
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• 2016

Objective: To compare dosimetric parameters of 3 dimensional conformal radiotherapy (3 DCRT) and intensity modulated radiotherapy (IMRT) in terms of target coverage and doses to organs at risk (OAR) in the management of rectal carcinoma. Methods: In this prospective study, conducted between August 2014 and March 2016, all patients underwent CT simulation along with a bladder protocol and target contouring according to the Radiation Therapy Oncology Group (RTOG) guidelines. Two plans were made for each patient (3 DCRT and IMRT) for comparison of target coverage and OAR. Result: A total of 43 patients were recruited into this study. While there were no significant differences in mean Planning Target Volume (PTV) D95% and mean PTV D98% between 3 DCRT and IMRT, mean PTV D2% and mean PTV D50% were significantly higher in 3 DCRT plans. Compared to IMRT, 3 DCRT resulted in significantly higher volumes of hot spots, lower volumes of cold spots, and higher doses to the entire OAR. Conclusion: This study demonstrated that IMRT achieves superior normal tissue avoidance (bladder and bowel) compared to 3 DCRT, with comparable target dose coverage.

• Asian Pacific Journal of Cancer Prevention
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• 제15권17호
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• pp.7401-7405
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• 2014

Background: Postoperative chemoradiotherapy is accepted as standard treatment for stage IB-IV, M0 gastric cancer. Radiotherapy (RT) planning of gastric cancer is important because of the low radiation tolerance of surrounding critical organs. The purpose of this study was to compare the dosimetric aspects of 2-dimensional (2D) and 3-dimensional (3D) treatment plans, with the twin aims of evaluating the adequacy of 2D planning fields on coverage of planning target volume (PTV) and 3D conformal plans for both covering PTV and reducing the normal tissue doses. Materials and Methods: Thirty-six patients with stage II-IV gastric adenocarcinoma were treated with adjuvant chemoradiotherapy using 3DRT. For each patient, a second 2D treatment plan was generated. The two techniques were compared for target volume coverage and dose to normal tissues using dose volume histogram (DVH) analysis. Results: 3DRT provides more adequate coverage of the target volume. Comparative DVHs for the left kidney and spinal cord demonstrate lower radiation doses with the 3D technique. Conclusions: 3DRT produced better dose distributions and reduced radiation doses to left kidney and spinal cord compared to the 2D technique. For this reason it can be predicted that 3DRT will result in better tumor control and less normal tissue complications.

• Radiation Oncology Journal
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• 제31권4호
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• pp.247-251
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• 2013

Purpose: This study aimed to investigate efficient approaches for determining internal target volume (ITV) from four-dimensional computed tomography (4D CT) images used in stereotactic body radiotherapy (SBRT) for patients with early-stage non-small cell lung cancer (NSCLC). Materials and Methods: 4D CT images were analyzed for 15 patients who received SBRT for stage I NSCLC. Three different ITVs were determined as follows: combining clinical target volume (CTV) from all 10 respiratory phases ($ITV_{10Phases}$); combining CTV from four respiratory phases, including two extreme phases (0% and 50%) plus two intermediate phases (20% and 70%) ($ITV_{4Phases}$); and combining CTV from two extreme phases ($ITV_{2Phases}$). The matching index (MI) of $ITV_{4Phases}$ and $ITV_{2Phases}$ was defined as the ratio of $ITV_{4Phases}$ and $ITV_{2Phases}$, respectively, to the $ITV_{10Phases}$. The tumor motion index (TMI) was defined as the ratio of $ITV_{10Phases}$ to $CTV_{mean}$, which was the mean of 10 CTVs delineated on 10 respiratory phases. Results: The ITVs were significantly different in the order of $ITV_{10Phases}$, $ITV_{4Phases}$, and $ITV_{2Phases}$ (all p < 0.05). The MI of $ITV_{4Phases}$ was significantly higher than that of $ITV_{2Phases}$ (p < 0.001). The MI of $ITV_{4Phases}$ was inversely related to TMI (r = -0.569, p = 0.034). In a subgroup with low TMI (n = 7), $ITV_{4Phases}$ was not statistically different from $ITV_{10Phases}$ (p = 0.192) and its MI was significantly higher than that of $ITV_{2Phases}$ (p = 0.016). Conclusion: The $ITV_{4Phases}$ may be an efficient approach alternative to optimal $ITV_{10Phases}$ in SBRT for early-stage NSCLC with less tumor motion.

• 대한방사선치료학회지
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• 제18권1호
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• pp.35-41
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• 2006

목 적: 유방암 방사선치료 시 유방(breast), 흉벽(chest wall, 국부적 임파관(loco-regional lymphatics) 등에 적정한 선량을 조사하기 위하여 다양한 치료계획이 이루어지고 있는데 이에 따른 선량분포를 정성적, 정량적으로 분석하여 최적의 방사선치료계획 기법을 고찰해 보고자 한다. 대상 및 방법: 최적의 유방암 방사선치료계획 기법을 평가하기 위해 기존의 전통적인 방법(2D)과 전산화단층촬영 영상에서 각각 유방체적을 설정하여 3차원적으로 접근하는 방법인 입체조형치료방법(3-dimensional conformal radiotherapy, 3DCRT)과 강도조절방사선치료 방법(intensity modulated radiotherapy, IMRT)을 비교하였다. 이를 위해 인체팬텀에 유방(breast), 흉벽(chest wall, 국부적 임파관(loco-regional lymphatics), 폐(lung) 등의 관심영역을 정하여 표지한 후 전산화단층촬영(Volume, Siemens, USA)을 시행하였다. 획득한 전산화단층촬영영상을 이용하여 입체조형치료방법과 강도조절방사선치료 방법을 적용하여 방사선치료계획(XiO 5.2.1, FOCUS, USA)을 수립하였고, 이는 기존의 전통적인 방법과 비교하였다. 비교, 분석은 방사선치료계획기법(2D, 3DCRT, IMRT)에 따른 방사선량분포와 선량-체적 간 히스토그람(dose-volume histogram, DVH) 및 관심영역의 점 선량 등을 분석하여 시행하였고, 또한 시간-노동력에 따른 치료효율성에 대해서도 평가하였다. 결 과: 유방체적을 설정하여 3차원 방사선치료계획 기법을 사용한 경우가 기존의 전통적인 방법에 비해 종양 설정과 빔 방향 및 조사면 경계 확인 등에 유용하다는 것을 알 수 있었다. 결 론: 유방암 방사선치료 시 방사선치료계획 기법에 따른 정성적, 정량적 분석을 통해 최적의 방사선치료계획 기법을 제시할 수 있었다. 그러나 3차원 방사선치료계획 시 치료계획종양용적(planning target volume, PTV) 설정과 유방 고정의 어려움에 따른 환자자세 재현성에 대한 문제를 알 수 있어 이에 대한 추가 연구가 필요할 것이라 사료된다.

• Radiation Oncology Journal
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• 제35권2호
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• pp.180-184
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• 2017

Patients with locally advanced lung cancer and very limited pulmonary function (forced expiratory volume in 1 second $[FEV1]{\leq}1L$) have dismal prognosis and undergo palliative treatment or best supportive care. We describe two cases of locally advanced node-positive non-small cell lung cancer (NSCLC) patients with very limited lung function treated with induction chemotherapy and moderate hypofractionated image-guided radiotherapy (Hypo-IGRT). Hypo-IGRT was delivered to a total dose of 45 Gy to the primary tumor and involved lymph nodes. Planning was based on positron emission tomography-computed tomography (PET/CT) and four-dimensional computed tomography (4D-CT). Internal target volume (ITV) was defined as the overlap of gross tumor volume delineated on 10 phases of 4D-CT. ITV to planning target volume margin was 5 mm in all directions. Both patients showed good clinical and radiological response. No relevant toxicity was documented. Hypo-IGRT is feasible treatment option in locally advanced node-positive NSCLC patients with very limited lung function ($FEV1{\leq}1L$).