title: Use of flattening filter-free photon beams in treating medulloblastoma: a dosimetric evaluation.
abstract: Aim. To evaluate the dosimetric benefits of flattening filter-free (FFF) photon beams in intensity modulated radiation therapy (IMRT) and Rapid Arc (RA) over conventional CSI methods. Methods and Materials. Five patients treated with IMRT using static multileaf collimators (MLC) were randomly selected for this retrospective study. Dynamic MLC IMRT, RA, and conformal therapy (3DCRT) were iterated with the same CT data sets with and without flattening filter photons. Total dose prescribed was 28.80 Gy in 16 fractions. Dosimetric parameters such as D max⁡, D min⁡, D mean, V 95%, V 107%, DHI, and CI for PTV and D max⁡, D mean, V 80%, V 50%, V 30%, and V 10% for OARs were extracted from DVHs. Beam on time (BOT) for various plans was also compared. Results. FFF RA therapy (6F_RA) resulted in highly homogeneous and conformal doses throughout the craniospinal axis. 3DCRT resulted in the highest V 107% (SD) 46.97 ± 28.6, whereas flattening filter (FF) and FFF dynamic IMRT had a minimum V 107%. 6F_RA and 6F_DMLC resulted in lesser doses to thyroid, eyes, esophagus, liver, lungs, and kidneys. Conclusion. FFF IMRT and FFF RA for CSI have definite dosimetric advantages over 3DCRT technique in terms of target coverage and OAR sparing. Use of FFF in IMRT resulted in 50% reduction in BOT, thereby increasing the treatment efficiency.
authors.affiliation: CyberKnife Center, HealthCare Global Enterprises, No. 7, HCG Tower 2, Kalinga Rao Road, Sampangiram Nagar, Bangalore 560 027, India.
authors.forename: Pichandi
authors.initials: P
authors.lastname: Anchineyan
authors.affiliation: Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore 560029, India.
authors.forename: Ganesh K
authors.initials: GK
authors.lastname: Mani
authors.affiliation: CyberKnife Center, HealthCare Global Enterprises, No. 7, HCG Tower 2, Kalinga Rao Road, Sampangiram Nagar, Bangalore 560 027, India.
authors.forename: Jerrin
authors.initials: J
authors.lastname: Amalraj
authors.affiliation: CyberKnife Center, HealthCare Global Enterprises, No. 7, HCG Tower 2, Kalinga Rao Road, Sampangiram Nagar, Bangalore 560 027, India.
authors.forename: Balaji
authors.initials: B
authors.lastname: Karthik
authors.affiliation: CyberKnife Center, HealthCare Global Enterprises, No. 7, HCG Tower 2, Kalinga Rao Road, Sampangiram Nagar, Bangalore 560 027, India.
authors.forename: Surega
authors.initials: S
authors.lastname: Anbumani