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
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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