Feasibility and early clinical assessment of flattening filter free (FFF) based stereotactic body radiotherapy (SBRT) treatments

Abstract

PurposeTo test feasibility and safety of clinical usage of Flattening Filter Free (FFF) beams for delivering ablative stereotactic body radiation therapy (SBRT) doses to various tumor sites, by means of Varian TrueBeam™ (Varian Medical Systems).Methods and MaterialsSeventy patients were treated with SBRT and FFF: 51 lesions were in the thorax (48 patients),10 in the liver, 9 in isolated abdominal lymph node, adrenal gland or pancreas. Doses ranged from 32 to 75 Gy, depending on the anatomical site and the volume of the lesion to irradiate. Lung lesions were treated with cumulative doses of 32 or 48 Gy, delivered in 4 consecutive fractions. The liver patients were treated in 3 fractions with total dose of 75 Gy. The isolated lymph nodes were irradiated in 6 fractions with doses of 45 Gy. The inclusion criteria were the presence of isolated node, or few lymph nodes in the same lymph node region, in absence of other active sites of cancer disease before the SBRT treatment.ResultsAll 70 patients completed the treatment. The minimum follow-up was 3 months. Six cases of acute toxicities were recorded (2 Grade2 and 2 Grade3 in lung and 2 Grade2 in abdomen). No patient experienced acute toxicity greater than Grade3. No other types or grades of toxicities were observed at clinical evaluation visits.ConclusionsThis study showed that, with respect to acute toxicity, SBRT with FFF beams showed to be a feasible technique in 70 consecutive patients with various primary and metastatic lesions in the body.

Optimizing the flattening filter free beam selection in RapidArc®-based stereotactic body radiotherapy for Stage I lung cancer

“…Additionally, many publications reported the clinical feasibility of FFF beams for SBRT treatment of NSCLC; [9][10][11][12][13] however, the most suitable fraction scheme for peripheral lung lesion is still questionable. Lower dose fraction schemes will narrow the treatment efficiency difference between the 6XFFF and 10XFFF beams according to our preliminary experiences.…”

“…[9][10][11] FFF beams are characterized by high dose rate and are most frequently utilized for treatments where higher fraction dose is delivered, including hypofractionated SBRT for NSCLC, liver and other sites. [9][10][11][12] 6XFFF and 10XFFF are the only FFF beam modes in Varian's TrueBeam™ accelerator (Varian® Medical Systems), and they are both widely used in SBRT treatment for lung cancer.…”

“…[9][10][11] FFF beams are characterized by high dose rate and are most frequently utilized for treatments where higher fraction dose is delivered, including hypofractionated SBRT for NSCLC, liver and other sites. [9][10][11][12] 6XFFF and 10XFFF are the only FFF beam modes in Varian's TrueBeam™ accelerator (Varian® Medical Systems), and they are both widely used in SBRT treatment for lung cancer. 9,10,[12][13][14] It is well known that the 10XFFF beam is produced with a dose rate of up to 2400 monitor units (MU) min 21 than 1400 MU min 21 for 6XFFF beam and consequently improves the treatment efficiency.…”

Stereotactic body radiation therapy in hepatocellular carcinoma: Optimal treatment strategies based on liver segmentation and functional hepatic reserve

“…By imageguided radiation therapy (IGRT) and the use of flattening filter-free (FFF) beams, setup accuracy and treatment delivery can minimize radiation-induced toxicity. [21][22][23] The preliminary results of SBRT treatment of HCC are encouraging. 24,25 SBRT may provide an alternative treatment option for early stage HCC patients or those ineligible for ablative procedures.…”

A surface energy spectral study on the bone heterogeneity and beam obliquity using the flattened and unflattened photon beams

“…Moreover, for the increasingly popular hypofractionated and stereotactic body radiotherapy, the unflattened photon beam is useful. [10][11][12][13][14][15] As some patients may be undergoing some kind of breath hold technique to manage respiratory motion issues, a fast treatment is necessary to take into account the patient's comfort and intrafraction organ motion. 12 While it is advantageous to use an unflattened photon beam in radiation dose delivery, the exclusion of the flattening filter from the beam has some dosimetric concerns.…”