Since HT can attain superior conformity of the dose distribution and homogeneity of the target dose, it has been widely adopted as a radiotherapy modality for various malignant tumors ( 2– 5). Helical tomotherapy (HT) utilizes the opening and closing of a 64-leaf, pneumatically powered, binary multileaf collimator with 51 equally-spaced beam angles at 360° and translational motion of the treatment couch at a constant speed to achieve a high degree of freedom and power in dose optimization ( 1). Both 2.5DJ or 5DJ were recommended for HT treatment plan for NPC based on the center workload. The BOT and MU of the groups using a 5.0-cm jaw width reduced nearly 45% comparing to those of the 2.5-cm jaw groups.Ĭonclusion: 2.5DJ has the best dose distribution, while 5.0DJ has satisfactory dose distribution and less BOT and MU that related to the leakage dose. The 2.5DJ group had the best ranking for OAR-dose, followed by the 2.5FJ and 5.0DJ groups with a same score. The groups using a 2.5-cm jaw width or a DJ mode provided better protection to most OARs, particularly for those at the longitudinal edges of the PTV ( P < 0.05). Results: The prescribed dose coverage of PTV met the clinical requirements for all plans in the four groups. The plans in each group were ranked by scoring the doses received by the OARs and the superity was assessed in combination with the planned BOT and MU. The dose parameters of planning target volume (PTV) and organs at risk (OARs) of the plans were compared and analyzed, as well as the beam on time (BOT) and monitor unit (MU). Four plans using a jaw width of 2.5 or 5-cm in dynamic jaw (DJ) or fix jaw (FJ) modes for irradiation were designed (2.5DJ, 2.5FJ, 5.0DJ, and 5.0FJ). Materials and Methods: Twenty patients with NPC who underwent radiotherapy were retrospectively selected. Purpose: To aid in the selection of a suitable combination of irradiation mode and jaw width in helical tomotherapy (HT) for the treatment of nasopharyngeal carcinoma (NPC). 3School of Biomedical Engineering, Sun Yat-sen University, Guangzhou, China.2School of Biomedical Engineering, Southern Medical University, Guangzhou, China.1Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangzhou, China.
Jun Zhang 1,2 †, Yinglin Peng 1,3 †, Shouliang Ding 1, Jinhan Zhu 1, Yimei Liu 1, Meining Chen 1, Wenzhao Sun 1, Linghong Zhou 2 * and Xiaowu Deng 1 *
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