flattening filter free beam

To compare the three-dimensional conformal radiotherapy (3DCRT), dynamic conformal arc therapy (DCA), and volumetric modulated arc therapy (VMAT) in stereotactic body radiation therapy (SBRT) of liver cases using 6MV and 10 MV flattened beam (FB) and flattening filter-free beam (FFFB).Twenty liver SBRT patients were selected. The dose prescription was 40 Gy delivered in 5 fractions. 3DCRT, DCA and VMAT planning was performed using 6 MV FB, 6 MV FFFB, 10 MV FB and 10 MV FFFB. Planning target volume (PTV) coverage, organs at risk (OARs) doses, monitor units (MU), and beam on time (BOT) were noted.VMAT plan produces better PTV coverage in the D98% and D95% region. 6 MV and 10 MV VMAT FB and FFFB reduced the D700cc, V10Gy, and Dmean of the liver minus gross tumor volume region compared to 3DCRT and DCA plans. FFFB in combination with VMAT producing highly conformal plan (Conformit index=1.19), better conformity number (CN=0.85), and lowering Paddick gradient index (GIpad=3.29) in comparison to 3DCRT and DCA. The FFFB needs higher monitor units to achieve the plan in all the techniques. FFFB reduces the BOT, body-PTV mean dose in the non-tumour volume. VMAT combined with FFFB will produce a highly conformal plan, spare the OAR’s, deliver fast and dose fall off in the body-PTV region is more as compared to 3DCRT and DCA. The VMAT will more advantage to treat the multiple lesions simultaneously and reducing the intra-fraction motion error in liver SBRT.

To study the impact of 6 MV and 10 MV flattened beam (FB) and flattening filter free (FFF) beam in whole brain radiotherapy (WBRT) by using volumetric modulated arc therapy (VMAT).
Twenty WBRTpatients were selected randomly. The dose prescription was 30 Gy, which was delivered in ten fractions. The planning target volume (PTV) and organs at risk (OARs) were contoured. Four VMAT plans, including 6 MV FB, 6 MV FFF, 10 MV FB, and 10 MV FFF beam plans, were generated.
The 6MV FB and FFF beam plans were statistically significant (p<0.05) in terms of the dose received by 98% of the PTV (D98%) (26.86 Gy vs. 27.31 Gy, P=0.006), the dose received by 95% of the PTV (D95%) (28.28 Gy vs. 28.52 Gy, P=0.038), 107% isodose (V107%) of the PTV (2.43% vs. 3.74%, P=0.001), D100% of the hippocampus (9.31 Gy vs. 9.16 Gy, P=0.009), and the Dmean scalp (16.7 Gy vs. 16.8 Gy, p=0.035). The 10 MV FB and FFF beam plans showed significant differences in the conformity index (0.9 vs. 0.85, P=0.01), V107% of the PTV (1.68% vs. 4.54%, P=0.001), D100% (10.08 Gy vs. 9.81 Gy, P=0.036), and Dmean of the hippocampus (12.78 Gy vs. 12.57 Gy, P=0.018). The 6 MV and 10 MV FFF beams showed homogeneous conformal plans, which required 18-19% more MUs, compared to the FB plans.
The 6 MV and 10 MV FB and FFFB spared the hippocampus and the scalp with acceptable target coverage in WBRT cases.

To study the impact of 6 MV and 10 MV flattened beam (FB) and flattening filter free (FFF) beam in whole brain radiotherapy (WBRT) by using volumetric modulated arc therapy (VMAT). Twenty WBRTpatients were selected randomly. The dose prescription was 30 Gy, which was delivered in ten fractions. The planning target volume (PTV) and organs at risk (OARs) were contoured. Four VMAT plans, including 6 MV FB, 6 MV FFF, 10 MV FB, and 10 MV FFF beam plans, were generated. The 6MV FB and FFF beam plans were statistically significant (p <0.05) in terms of the dose received by 98% of the PTV (D98%) (26.86 Gy vs. 27.31 Gy, P=0.006), the dose received by 95% of the PTV (D95%) (28.28 Gy vs. 28.52 Gy, P=0.038), 107% isodose (V107%) of the PTV (2.43% vs. 3.74%, P=0.001), D100% of the hippocampus (9.31 Gy vs. 9.16 Gy, P=0.009), and the Dmean scalp (16.7 Gy vs. 16.8 Gy, p=0.035). The 10 MV FB and FFF beam plans showed significant differences in the conformity index (0.9 vs. 0.85, P=0.01), V107% of the PTV (1.68% vs. 4.54%, P=0.001), D100% (10.08 Gy vs. 9.81 Gy, P=0.036), and Dmean of the hippocampus (12.78 Gy vs. 12.57 Gy, P=0.018). The 6 MV and 10 MV FFF beams showed homogeneous conformal plans, which required 18-19% more MUs, compared to the FB plans. The 6 MV and 10 MV FB and FFFB spared the hippocampus and the scalp with acceptable target coverage in WBRT cases.

In the treatment of prostate cancer, radiotherapy is the potential to increase second primary cancers such as bladder and rectal cancers. The reasons for this potential are more monitor units (MUs), therefore a larger total body dose because of leakage radiation, a bigger volume of normal tissue is exposed to lower radiation doses. This study was designed to compare the integral dose of using Flattening Filter (FF) and Flattening Filter-Free (FFF) 6 and 10 MV photon beams via volumetric modulated arc therapy (VMAT) for prostate cancer patients. Twenty prostate cancer patients were selected retrospectively for this planning study. VMAT plans were developed using the Eclipse (Varian Medical System, Palo Alto, California, USA) Treatment Planning System (TPS) with 6 MV FF, 6 MV FFF, 10 MV FF and 10 MV FFF for each patient. Conformity index (CI), homogeneity index (HI), Integral dose (ID), the volume receiving 5 Gy (V5%) and monitor units (MUs) were compared. The use of 10 MV FF had 206 liter*Gy integral dose to Body-CTV volume. Using 10 MV FFF had 204 liter*Gy integral dose to normal structures. When 10 MV FF or 10 MV FFF were used instead of 6 MV FF and 6 MV FFF integral dose decreased as -7% and -8%, respectively. The dosimetric difference were statistically significant (p<0.05). The use of 10 MV FFF rather than 10 MV FF had limited influence on the integral dose for rectum, bladder, penile bulb and femoral heads. This study showed that high energy photons (10 MV FF, 10 MV FFF) have lower integral dose than low energy photons (6 MV FF, 6 MV FFF). The relationship between low energies, high energies and integral doses is significant, although there is no significant relationship between V5% doses of all energies. In comparison to different treatment plans, we showed that V5% alone did not provide enough information when possible secondary cancer risks were calculated.