Analysis presented in this paper, demonstrated that RapidArc can compete with the IMRT technique in the field of treatment plan dosimetry reducing the time required for dose delivery.

Abstract. The aim of the present study was to compare the techniques of dynamic intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT) in patients with gastric cancer. Implementation of the IMRT technique does not significantly affect the minimum and maximum dose levels in the planning target volume (PTV), but more effectively protects the critical organs. The study group consisted of 25 patients. The results of the analysis of the conformity index (CI) and the homogeneity index (HI) showed that the doses in the PTV regions were at a comparable level. The CI for the PTV was 0.95 for the 2-field technique, 0.95 for the 3-field technique, 0.96 for the 4-field technique and 0.94 for the IMRT technique. The CIs for these techniques for the clinical target volume (CTV) were 0.96, 0.96, 0.97 and 0.96, respectively, and the CIs for the gross tumor volume (GTV) were 0.99, 0.99, 0.99 and 0.98, respectively. The HI values for the PTV were 1.12 for the 2-field technique, 1.12 for the 3-field technique, 1.09 for the 4-field technique and 1.09 for the IMRT technique, and the HI values for the CTV were 1.12, 1.12, 1.09 and 1.08 for the same techniques, respectively. The HI values for the GTV were 1.09, 1.09, 1.07 and 1.06, respectively, which indicated significantly superior performance in the regions of healthy tissue. Statistical study was based on Friedman's rank analysis of variance to determine the level of reliability of the tested groups of variables (P<0.001). The present study demonstrated that the IMRT technique in the pre-operative radiotherapy of gastric cancer patients results in superior treatment tolerance and reduces the risk of damage to healthy tissue that is in close proximity to the irradiated area.

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Treatment plan comparisonGastric cancer Conformal radiotherapy a b s t r a c tAim: The purpose of this study was to compare conformal radiotherapy techniques used in the treatment of gastric cancer patients. The study is dedicated to radiotherapy centres that have not introduced dynamic techniques in clinical practice. Background:The implementation of multi-field technique can minimise the toxicity of treatment and improve dose distribution homogeneity in the target volume with simultaneous protection of organs at risk (OaRs). Treatment plan should be personalised for each patient by taking into account the planning target volume and anatomical conditions of the individual patient. Materials and methods:For each patient, four different three dimensional conformal plans were compared: 2-field plan, 3-field plan, non-coplanar 3-field plan and non-coplanar 4-field plan. Dose distributions in a volume of 107% of the reference dose, and OaRs such as the liver, kidneys, intestines, spinal cord, and heart were analysed. Results BackgroundGastric cancer is the third most frequent cause of death from cancer worldwide, with 723,027 deaths registered in 2012. 1 The primary treatment modality of gastric cancer is surgery. 16 This treatment strategy is frequently employed in the early stage of cancer. Radical operation (R0) can be performed in approximately 50% of patients because of the diagnosis of cancer in the locally advanced or dispersal stage. Since the INT-0116 study was published, the standard for pT 2-4 N 0-3 or pT 1 N 1-3 gastric cancer is postoperative radiochemotherapy. 2,6 At some oncology centres, R1 surgical resection is also an indication for postoperative radiochemotherapy. 3 Implementation of this scheme enhances both local cure and the 5-year survival by approximately 15% compared with independent surgery treatment. Initially, at many radiotherapy departments, a recommended two dimension (2D) technique using two opposing fields was applied for gastric cancer treatment. The constraint of 2D radiotherapy for the abdominal area is the close localisation of organs at risk such as the kidneys, liver, intestines and spinal cord. Consequently, this radiotherapy induced high hematologic toxicity of the digestive system and was completed earlier than planned in 17% of patients. 4 With recent advances in technology, computer dose distribution calculations have been shown to allow the introduction of three dimension (3D) conformal techniques (conformal radiotherapy; CRT) in common applications. These techniques turn out to be more effective in achieving high, homogeneous dose distribution in the target volume with simultaneous sparing of normal tissues. In the 3D conformal technique the shape of the planning target volume (PTV), mutual localisation of the target volume and organs at risk are all considered. 5 Dose distribution in the 3D technique allows the acquisition of more information than that in 2D planning. 3D planning exposes the local maximum of the dose distribution (hot spots) or allows localised region...