Evaluation and comparison of dose distributions for nasopharyngeal carcinoma patients treated by Jaws-Only IMRT technique and by 3D-CRT technique at Dong Nai General Hospital

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Tác giả: Thanh Tài Dương, Đông Sơn Nguyễn, Thị Hồng Trang Nguyễn, Thị Hồng Loan Trương

Ngôn ngữ: vie

Ký hiệu phân loại: 571.45 *Radiobiology

Thông tin xuất bản: Tạp chí Phát triển Khoa học & Công nghệ, 2017

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Bộ sưu tập: Metadata

ID: 492446

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The goal of radiation therapy is twofold: maximize the possibility of destroy malignant cells while minimizing the damage to healthy tissue. The introduction of intensity modulated radiation therapy (IMRT) technique has brought improvements in this goal. Multi-leaf collimator (MLC) is a useful tool for IMRT. However, the use of MLC is not necessarily mandatory. The Panther Treatment Planning System version 4.6, Prowess Inc., enables the implementation of this technique for accelerator without MLC (the so-called Jaws-Only IMRT technique). This study aims to evaluate the results of application of Jaws-only IMRT technique for nasopharyngeal carcinoma patients at Dong Nai general hospital. Twenty five patients were randomly selected for this study. For each patient, two plans were generated: 3D-CRT (Three-Dimensional Radiation Treatment) and JO-IMRT. The dose distributions, dose-volume histograms (DVH), conformity indexes (COIN), homogeneity indexes (HI) were used to compare between these two plans and find out the best plan. Pretreatment verifications were performed for all patients' plans using ion chamber (Farmer Type Chamber FC65-P, IBA), detector array (MapCHECK2, Sun Nuclear Corporation and Octavius 4D 1500, PTW). The average deviation between measurement and calculation for point dose was 2.3±1.1 %, within limit dose constraint. For detector array measurements, the gamma index with 3 % dose difference and 3 mm was higher than 95 %. The results showed that the JO-IMRT technique had generated better dose distribution in the target volume and reduced dose to healthy tissues compared to 3D-CRT.Xạ trị điều biến cường độ (Intensity-Modulated Radiation Therapy, IMRT) là một kỹ thuật tiên tiến trong xạ trị, bắt đầu phổ biến từ 1994 [1, 2]. Kỹ thuật này thường được áp dụng với máy gia tốc có trang bị ống chuẩn trực đa lá (Multileaf collimator, MLC). Tuy nhiên, không phải trung tâm xạ trị nào cũng có máy gia tốc với hệ MLC. Mục tiêu của bài báo này là đánh giá kỹ thuật IMRT cho ung thư vòm với hệ máy gia tốc không có MLC tại Bệnh viện Đa khoa Đồng Nai. Kỹ thuật này được gọi là Jaws Only-IMRT (JO-IMRT), được thực hiện dựa trên hệ thống phần mềm lập kế hoạch xạ trị Prowess Panther 4.6 (nhà cung cấp Prowess, Mỹ) [3]. Trong nghiên cứu này, chúng tôi chọn 25 bệnh nhân ung thư vòm. Mỗi một bệnh nhân đều được lập hai kế hoạch: 3D-CRT và JO-IMRT. Sau đó, phân bố liều trên từng lát cắt, biểu đồ liều lượng thể tích (Dose-volume histogram, DVH), chỉ số tương quan liều (Conformity index, COIN), chỉ số đồng nhất (Homogeneity index, HI) của hai kế hoạch này được sử dụng để so sánh, đánh giá và tìm ra kế hoạch tối ưu nhất. Các kế hoạch này cần được kiểm tra độ chính xác về liều lượng (QA) trước khi điều trị. Phương tiện sử dụng là buồng ion hóa FC65-P của hãng IBA để đo liều điểm và ma trận các đầu dò Mapcheck2 của hãng Sunnuclear và Octavius 4D của hãng PTW để đo liều phân bố. Sai số liều điểm giữa tính toán và thực nghiệm là 2,2±1,4 %. Đối với liều phân bố thì chỉ số Gamma trung bình >
95 %. Chỉ số COIN là 0,87 ± 0,05 và HI là 0,096 ± 0,002. Sai số giữa liều tính toán và thực nghiệm ở trong giới hạn cho phép (

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