Abstract
Background and purposeFlattening filter free (FFF) beams with high dose rate are increasingly used for stereotactic body radiotherapy (SBRT), because they substantially shorten beam-on time. The physical properties of these beams together with potentially unknown radiobiological effects might affect patient safety. Therefore here we analyzed the clinical outcome of our patients.Material and methodsBetween 3/2010 and 2/2014 84 patients with 100 lesions (lung 75, liver 10, adrenal 6, lymph nodes 5, others 4) were treated with SBRT using 6 MV FFF or 10 MV FFF beams at our institution. Clinical efficacy endpoints and toxicity were assessed by Kaplan-Meier analysis and CTCAE criteria version 4.0.ResultsMedian follow-up was 11 months (range: 3–41). No severe acute toxicity was observed. There has been one case of severe late toxicity (1%), a grade 3 bile duct stricture that was possibly related to SBRT. For all patients, the 1-year local control rate, progression free survival and overall survival were 94%, 38% and 80% respectively, and for patients with lung lesions 94%, 48% and 83%, respectively.ConclusionsNo unexpected toxicity occurred. Toxicity and treatment efficacy are perfectly in range with studies investigating SBRT with flattened beams. The use of FFF beams at maximum dose rate for SBRT is time efficient and appears to be safe.
Highlights
Background and purposeFlattening filter free (FFF) beams with high dose rate are increasingly used for stereotactic body radiotherapy (SBRT), because they substantially shorten beam-on time
flattening filter free (FFF) beams at maximum dose rate have been rapidly introduced into clinical use, little clinical data about their safety and efficacy are available
With the lack of a clear biological rationale not to use FFF beams we introduced this technology assuming that the benefit in terms of increased treatment efficiency would outweigh the minimal risk of additional toxicity
Summary
Flattening filter free (FFF) beams with high dose rate are increasingly used for stereotactic body radiotherapy (SBRT), because they substantially shorten beam-on time. A major advantage of using flattening filter free (FFF) beams is that the dose rate can be multiplied in comparison to flattened beams thereby shortening beam-on time [1,2]. This is especially attractive when a high dose per fraction is used, e.g. in the case of stereotactic body radiotherapy (SBRT). FFF beams at maximum dose rate have been rapidly introduced into clinical use, little clinical data about their safety and efficacy are available. It may introduce novel hazards, e.g. in case of patient or organ
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