Earticle

본 논문은 NP-완전 문제로 분류된 최소 가중치 연결 지배집합 문제(MWCDSP)에 대해 다항시간의 정확한 해를 찾는 알고리즘을 제안하였다. MWCDSP의 최적 해를 직접적으로 찾는 규칙을 발견하는 것은 불가능에 가깝다. MWCDSP의 전제조건은 최소 가중치 합과 연결된 최소 노드 수를 충족시켜야만 한다. 본 논문은 먼저 최소 가중치 합을 가진 개 노드를 연결하는 MST를 구하였다. 다음으로 연결된 최소 노드 수 조건을 충족시키기 위해 MST의 내부 노드 들 중에서 차수가 2 이상인 단 노드들을 지배하는 노드를 단 노드로 변환시켜 연결된 노드 수를 줄였다. 제안된 알고리 즘을 14개의 다양한 유형의 망에 대해 적용한 결과 모든 망에서 최적 해를 찾을 수 있음을 보였다.

This paper proposes an algorithm to find the exact solution of polynomial time for the minimum weighted connected dominating set problem(MWCDSP) classified as NP-complete problem. It is almost impossible to find a rule that directly finds the optimal solution of MWCDSP. The prerequisite for MWCDSP must meet the minimum sum of weights and the minimum number of connected nodes with it. This paper first obtains an MST that connecting n nodes with a minimum weighted sum. Next, in order to meet the condition of the minimum number of connected nodes, the nodes that dominating the terminal nodes with a degree of 2 or higher among the internal nodes of the MST were converted to the terminal nodes to reduce the number of connected nodes. The application of the proposed algorithm to 14 different types of networks shows that the optimal solution can be found in all networks.

목적: 방사선 폐렴과 체적-선량 히스토그램(dose-volume hlstogram, DVH) 변수들 사이의 연관성을 평가하고, 내유림프절이 포함된 유방암의 방사선치료에서 방사선 폐렴을 방지할 수 있는 실제적인 지침을 제공하고자 한다. 대상 및 방법: 부분유방절제술을 받은 초기 유방암 환자 20명이 본 연구에 포함되었다. 전체 유방, 상부쇄골림프절, 내유림프절에 총 28회 50.4 Gy가 조사되었다. 방사선 폐렴은 방사선 영상에서의 폐 변화(radiological pulmonary change; RPC)와 증상이 있는 방사선 폐렴(symptomatic radiation pneumonitis)에 의해 평가되었다 DVH 변수들은 grade<2 RPC와 grade${\geq}$2 RPC로 나누어 비교되었다. 이 때, DVH 변수들은 평균 폐 선량(mean lung dose), V10 (10 Gy 이상 받는 폐의 백분율 부피), V20, V30, V40, 그리고 정상 조직 합병증 확률(normal tissue complication probability, NTCP)이다. 결 과: 20명의 환자 중 9명(45%)에서 grade 2 RPC가 발생하였고, 11명(55%)에서는 발생하지 않았다 1명의 환자에서 grade 1의 증상이 있는 방사선 폐렴이 발생하였다. 단변량 분석에서 DVH 변수 중, NTCP가 두 RPC grade군 간에 유의한 차이를 보여주고 있다 (p<0.05) Fisher의 정확한 검증(exact test)은 NTCP값 45%가 RPC의 threshold level로서 적합함을 보여준다. 결 론: 본 연구는 NTCP가 유방암의 내유림프절 방사선치료 후 RPC 예측인자 중 한가지로 쓰일 수 있음을 보여준다. 임상적으로 이는 NTCP 45% 이상에서 RPC가 발생하기 용이함을 의미한다.

Purpose: To evaluate the association between radiation pneumonitis and dose-volume histogram parameters and to provide practical guidelines to prevent radiation pneumonitis following radiotherapy administered for breast cancer including internal mammary lymph nodes. Materials and Methods: Twenty patients with early breast cancer who underwent a partial mastectomy were involved in this study. The entire breast, supraclavicular lymph nodes, and internal mammary lymph nodes were irradiated with a dose of 50.4 Gy in 28 fractions. Radiation pneumonitis was assessed by both radiological pulmonary change (RPC) and by evaluation of symptomatic radiation pneumonitis. Dose-volume histogram parameters were compared between patients with grade <2 RPC and those with grade ${\geq}$2 RPC. The parameters were the mean lung dose, V10 (percent lung volume receiving equal to and more than 10 Gy), V20, V30, V40, and normal tissue complication probability (NTCP). Results: Of the 20 patients, 9 (45%) developed grade 2 RPC and 11 (55%) did not develop RPC (grade 0). Only one patient developed grade 1 symptomatic radiation pneumonitis. Univariate analysis showed that among the dose-volume histogram parameters, NTCP was significantly different between the two RPC grade groups (p<0.05). Fisher's exact test indicated that an NTCP value of 45% was appropriate as an RPC threshold level. Conclusion: This study shows that NTCP can be used as a predictor of RPC after radiotherapy of the internal mammary lymph nodes in breast cancer. Clinically, it indicates that an RPC is likely to develop when the NTCP is greater than 45%.

Purpose The purpose of this study was to detect the lymphatic drainage pattern of internal mammary area and verify the concept of internal mammary sentinel lymph node (IM-SLN) in breast. Materials and Methods A small particle radiotracer (99mTc-Dextran 40) was prepared and tested. 99mTc-Dextran 40 was injected into intraparenchyma at the sound breast by a modified radiotracer injection technique. Subsequently, dynamic single-photon emission computed tomography (SPECT), computed tomography (CT), and SPECT/CT combination images were performed to identify the radioactive lymph vessels and internal mammary lymph nodes (IMLNs). The direction of lymph drainage and the location of the IMLNs were identified in the SPECT/CT imaging. Results The radiochemical purity of 99mTc-Dextran 40 was > 95%. 99mTc-Dextran 40 could drainage into first, second, and third lymph node and the radioactive lymph node could be detected by the ? detector in the animal experiment. After 99mTc-Dextran 40 injecting into intraparenchyma, 50.0% cases (15/30) were identified the drainage lymphatic vessels and radioactive IMLNs by SPECT. The drainage lymphatic vessel was found from injection point to the first IMLN (IM-SLN) after 10.5±0.35 minutes radiotracer injection, and then 99mTc-Dextran 40 was accumulated into the IM-SLN. The combination imaging of SPECT/CT showed the second IMLN received the lymph drainage from the IM-SLN. The lymphatic drainage was step by step in the internal mammary area. Conclusion The lymph was identified to drain from different regions of the breast to IM-SLN, and then outward from IM-SLN to other IMLN consecutively. It demonstrated the concept of the IM-SLN and provided more evidences for the application of internal mammary sentinel lymph node biopsy.

Purpose The purpose of this study was to evaluate the treatment outcomes of radiotherapy (RT) for breast cancer with ipsilateral supraclavicular (SCL) and/or internal mammary (IMN) lymph node involvement. Materials and Methods A total of 353 patients from 11 institutions were included. One hundred and thirty-six patients had SCL involvement, 148 had IMN involvement, and 69 had both. All patients received neoadjuvant systemic therapy followed by breast-conserving surgery or mastectomy, and postoperative RT to whole breast/chest wall. As for regional lymph node irradiation, SCL RT was given to 344 patients, and IMN RT to 236 patients. The median RT dose was 50.4 Gy. Results The median follow-up duration was 61 months (range, 7 to 173 months). In-field progression was present in SCL (n=20) and/or IMN (n=7). The 5-year disease-free survival (DFS) and overall survival rates were 57.8% and 75.1%, respectively. On multivariate analysis, both SCL/IMN involvement, number of axillary lymph node ? 4, triple-negative subtype, and mastectomy were significant adverse prognosticators for DFS (p=0.022, p=0.001, p=0.001, and p=0.004, respectively). Regarding the impact of regional nodal irradiation, SCL RT dose ? 54 Gy was not associated with DFS (5-year rate, 52.9% vs. 50.9%; p=0.696) in SCLinvolved patients, and the receipt of IMN RT was not associated with DFS (5-year rate, 56.1% vs. 78.1%; p=0.099) in IMN-involved patients. Conclusion Neoadjuvant chemotherapy followed by surgery and postoperative RT achieved an acceptable in-field regional control rate in patients with SCL and/or IMN involvement. However, a higher RT dose to SCL or IMN RT was not associated with the improved DFS in these patients.