Influence of Lymph Node Clinical Target Volume Margin Size on Liver and Kidneys in Three Dimensional Conformal Radiotherapy of Gastric Cancer: A Dosimetric Analysis Hasan Osmic 1* , Hasukic S 2 , Hasukic B 2 , Fazlic S 3 and Đedovic E 3,4 1 Radiotherapy and Oncology Clinic, University Clinical Center Tuzla, Bosnia and Herzegovina 2 Surgery Clinic, University Clinical Center Tuzla, Bosnia and Herzegovina 3 Department of Medical Physics and Radiation Protection, University Clinical Center Tuzla, Bosnia and Herzegovina 4 Department of Physics, University of Tuzla, Bosnia and Herzegovina * Corresponding author: Hasan Osmic, Radiotherapy and Oncology Clinic, University Clinical Center T uzla, City of T uzla, Bosnia and Herzegovina, Tel: +38735303486; Fax number: +38735303389; E-mail: hasan.osmic@ukctuzla.ba Received date: August 10, 2018; Accepted date: August 31, 2018; Published date: September 07, 2018 Copyright: ©2018 Osmic H, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract The aim of this study was to determine the dosimetrically optimal CTV margin for lymph nodes in patients with gastric cancer treated with 3DCRT. We derived three PTVs for every patient: PTV 5 mm, PTV 7 mm and PTV 10 mm. For each patient, 3DCRT treatment plans were prepared for each of the three PTVs. From DVHs, for every patient and margin size, mean values and ranges of doses to organs at risk, as well as mean values and ranges of V 28 , V 23 , V 20 and V 12 for both kidneys were recorded. Standard deviations of data were also calculated for every particular case. Statistical hypotheses were tested for α=0.05 significance level, i.e. differences between the examined groups were considered significant if p<0.05. As a result we got that: The difference is significantly lower in the mean dose to liver for CTV 5 mm and CTV 10 mm, as well as for CTV 7 mm and CTV 10 mm; the difference is not significant for CTV 5 mm and CTV 7 mm; A significantly lower difference is seen in the mean dose to the right and left kidneys for CTV 5 mm and CTV 10 mm, CTV 7 mm and CTV 10 mm, while no significant difference is observed for CTV 5 mm and CTV 7 mm. We concluded that the margin of the nodal CTV of 7 mm in 3DCRT of gastric cancer dosimetrically spares liver and kidneys better than the CTV 10 mm margin. Keywords: Gastric cancer; Lymph node CTV; 3DCRT; Organ at risk; Dosimetric analysis; DVH. Abbreviations: CTV: Clinical Target Volume; PTV: Planning Target Volume; OAR: Organ at Risk; DVH: Dose Volume Histogram; FOV: Field of View; CT: Computed Tomography; MLC: Multileaf Collimator; RLAT: Right Lateral; LLAT: Left Lateral; QUANTEC: Qualitative Analyses of Normal Tissue Effect in the Clinic; ANOVA: Analysis of Variance; Introduction Gastric cancer is the third most common cause of cancer death worldwide. Te highest incidence rate is recorded in East Asia, South America and East Europe, whereas the lowest is found in North America [1]. It is a relatively rare type of cancer in the USA with the incidence of 10,000 deaths per year [2]. Surgery is the primary therapy for all operable gastric cancers. Surgery technique depends mostly on cancer localization, size and local status. It should be pointed out that D2 lymphadenectomy is a mandatory standard in such procedures [3]. Te role of radiotherapy in gastric cancer treatment has signifcantly changed in the frst decade of the 21 st century. It was considered an inefective method in the treatment of these types of cancers, however, afer the introduction of the 3D planning and other complex radiation techniques and in combination with a sequential and concomitant chemotherapy, it has become more commonly used postoperative method of treatment [4]. Delineation of the tumor CTV is a demanding procedure. It includes CTV of the tumor bed, anastomosis and lymph nodes. When determining the tumor bed and anastomosis, it is recommended to do a preoperative CT [5,6]. Stomach lymphatic drainage is very complex and depends on primary localization of gastric cancer. Caravatta et al. have recommended that lymph node stations, depending on the tumor localization, be included in radiotherapy of gastric cancer [7]. 3DCRT can be used to create a dosimetric plan where the prescribed dose is drawn near the target volume to increase organs at risk sparing, primarily liver and kidneys. Te condition is to precisely contour the target volume in order to avoid under-irradiation and locoregional disease recurrence. Te biggest challenge is to determine the distance between the blood vessels and the largest number of lymph nodes in order to set the optimal CTV of lymph nodes. Pancreas and stomach have very similar vascularization and lymphatic drainage, especially at the level of the J o u r n a l o f N u c l e a r M e d i c i n e & R a d i a t i o n T h e r a p y ISSN: 2155-9619 Journal of Nuclear Medicine & Radiation Therapy Osmic et al., J Nucl Med Radiat Ther 2018, 9:5 DOI: 10.4172/2155-9619.1000374 Research Article Open Access J Nucl Med Radiat Ter, an open access journal ISSN: 2155-9619 Volume 9 • Issue 5 • 1000374 EORTC: European Organisation for Rsearch and Treatment of Cancer. ROG: Radiation Oncology Group; AP: Anterior- Posterior; 3DCRT: Three Dimensional Conformal Radio Therapy;