Validation of lung stereotactic ablative body radiotherapy (SABR) treatments with flattening filter free (FFF) beams. (September 2016)

• Record Type: Journal Article
• Authors: Floros, Ioannis; Bangiri, Anna; Jolliffe, Greg; Littler, Jonathan; Harron, Elizabeth; Mckenna, Angela; Langmack, Keith
• Is Part Of: Physica medica. Volume 32(2016)Supplement 3
• Page Start: 289
• Publication Date: 2016-09
• Subjects: Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2016.07.111
• Languages: English
• ISSNs: 1120-1797

Abstract

Abstract : Introduction: To commission and dosimetrically validate MONACO TPS for lung SABR treatments using FFF beams. Materials and methods: EBT3 films were used and the region of interest was the Field Edge Area (FEA): 20–80% of dose maximum. The film was placed in water and lung phantom and three field sizes were used. Profiles were measured from the film and the FEA was calculated and compared to that from the TPS. Clinical plans were created using three fractionation regimes (54Gy/3#, 55Gy/5#, 60Gy/8#) for each of four patients. Each plan was delivered twice on the Quasar phantom, with a breathing trace and statically, and on the Delta4 phantom. Results: The profile differences between films and Monaco TPS were primarily within 1mm for all field sizes and at all depths. The largest difference in lung was 0.7, 1.2 and 1.0 mm in the crossline direction for 10 × 10, 5 × 5, and 2 × 2 cm 2 respectively. The respective differences in the inline direction were 2.2, 1.2 and 1.0 mm. The FEA calculated with Monaco was overall broader than that measured. All the delivered plans had a gamma pass rate better than 98.3% (3 mm/3%)on the Delta4. The Quasar results had a mean absolute dose difference of 1.1% (S.D. 0.7) and 1.3% (S.D. 0.9) for the static and the breathing traces respectively. Conclusion: The excellent agreement with EBT3 indicates that Monaco satisfactorily predicts profiles in lung. The differences observed could be due to partial volume effect. FFF Lung SABR treatments were fully verified and excellent agreement was found with the Quasar and the Delta4 for all clinical plans.