Stereotactic body radiation therapy in lung and hepatic cancer (SBRT) with helical tomotherapy (HT): Description of our method
| Autor: | M. Erzilbengoa, L. Bragado Alvarez, A. Guisasola, S. C. Moral Sanchez |
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| Rok vydání: | 2013 |
| Předmět: |
Lung
business.industry Stereotactic body radiation therapy medicine.medical_treatment Biophysics General Physics and Astronomy General Medicine Dose constraints Tomotherapy Conformity index medicine.anatomical_structure Adaptive planning Treatment plan Medicine Radiology Nuclear Medicine and imaging business Nuclear medicine Homogeneity index |
| Zdroj: | Physica Medica. 29:e30 |
| ISSN: | 1120-1797 |
| Popis: | Introduction We chose to implement the technique of SBRT in lung and liver lesions with Helical Tomotherapy (HT) for its high accuracy and dosimetric quality obtained, so as to deliver at least 1 Gy per minute for PTV less than 5 cm in optimal conditions for the machine (Gantry rotation, couch motion, leaf open time). Materials and methods From June 2012 until March 2013, 6 patients with 10 lung lesions and 2 patients with liver lesions were treated with HT-SBRT. Internal tumor volume (ITV) is defined by the sum of the GTV from 4 sets of kV-CT (The dose calculation using a density averaged ITV for lung lesions) and a series PET SCAN in free-breathing, patient immobilized with diaphragmatic compression Body ProLock commercialized by Civco ® . Planned treatment volume (PTV) consisted of 5-mm radial and a 10-mm craniocaudal expansion of ITV. The prescribed doses were: 3 × 20Gy, 3 × 18Gy, 8 × 7,5 Gy. Dose constraints to normal tissue were defined accorded to RTOG 0236 and 0438 protocols. The characteristics of the treatment plan (Pitch = 0.86/ n (0.123), modulation factor (1.5), field size (2.5 or 1 cm)) were chosen to achieve a compromise dosimetric quality (homogeneity index HI and conformity index CI)/ processing time. Results The average homogeneity and conformity index that we obtained are 1.04 and 0.96. Accurate positioning of the patient and control intra and post fraction of it through MVCT scan and adaptive planning tool allows us to assess for central pulmonary and hepatics lesions displacements in x, y and z Conclusions HT-SBRT is feasible, accurate and well tolerated for lung and liver lesions. The improvement of our methodology will be to introduce the 4D PET to define a more precise ITV and to make the calculation on a weighted averaged density scan. |
| Databáze: | OpenAIRE |
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