Planning evaluation of radiotherapy for complex lung cancer cases using helical tomotherapy
Autor: | Grigor N. Grigorov, Tomas Kron, Edward Yu, Jake Van Dyk, Jeff Z. Y. Chen, Kris Trenka, T. Coad, George Rodrigues, Glenn Bauman, Eugene Wong, Slav Yartsev |
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Rok vydání: | 2004 |
Předmět: |
Male
Hot Temperature Lung Neoplasms Time Factors medicine.medical_treatment Radiotherapy Planning Planning target volume Bioimaging and Biomedical Optics Tomotherapy Dose-Response Relationship Computer-Assisted Models Carcinoma Non-Small-Cell Lung Humans Medicine Radiology Nuclear Medicine and imaging Lung volumes Stage (cooking) Non-Small-Cell Lung Radiometry Radiation treatment planning Lung cancer Lung Radiation Models Statistical Radiotherapy Radiological and Ultrasound Technology Mean lung dose Conformal business.industry Radiotherapy Planning Computer-Assisted Carcinoma Dose-Response Relationship Radiation Radiotherapy Dosage Statistical medicine.disease Radiotherapy Computer-Assisted Radiation therapy Oncology Lymphatic Metastasis Medical Biophysics Female Radiotherapy Conformal business Nuclear medicine |
Zdroj: | Edward Yu Oncology Publications |
ISSN: | 1361-6560 0031-9155 |
Popis: | Lung cancer treatment is one of the most challenging fields in radiotherapy. The aim of the present study was to investigate what role helical tomotherapy (HT), a novel approach to the delivery of highly conformal dose distributions using intensity-modulated radiation fan beams, can play in difficult cases with large target volumes typical for many of these patients. Tomotherapy plans were developed for 15 patients with stage III inoperable non-small-cell lung cancer. While not necessarily clinically indicated, elective nodal irradiation was included for all cases to create the most challenging scenarios with large target volumes. A 2 cm margin was used around the gross tumour volume (GTV) to generate primary planning target volume (PTV2) and 1 cm margin around elective nodes for secondary planning target volume (PTV1) resulting in PTV1 volumes larger than 1000 cm3 in 13 of the 15 patients. Tomotherapy plans were created using an inverse treatment planning system (TomoTherapy Inc.) based on superposition/convolution dose calculation for a fan beam thickness of 25 mm and a pitch factor between 0.3 and 0.8. For comparison, plans were created using an intensity-modulated radiation therapy (IMRT) approach planned on a commercial treatment planning system (TheraplanPlus, Nucletron). Tomotherapy delivery times for the large target volumes were estimated to be between 4 and 19 min. Using a prescribed dose of 60 Gy to PTV2 and 46 Gy to PTV1, the mean lung dose was 23.8+/-4.6 Gy. A 'dose quality factor' was introduced to correlate the plan outcome with patient specific parameters. A good correlation was found between the quality of the HT plans and the IMRT plans with HT being slightly better in most cases. The overlap between lung and PTV was found to be a good indicator of plan quality for HT. The mean lung dose was found to increase by approximately 0.9 Gy per percent overlap volume. Helical tomotherapy planning resulted in highly conformal dose distributions. It allowed easy achievement of two different dose levels in the target simultaneously. As the overlap between PTV and lung volume is a major predictor of mean lung dose, future work will be directed to control of margins. Work is underway to investigate the possibility of breath-hold techniques for tomotherapy delivery to facilitate this aim. |
Databáze: | OpenAIRE |
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