Average dose-volume histogram (DVH) comparison for lung and heart with four different planning techniques.

6F-IMRT = six large fields IMRT plans with fixed jaw; 6F-IMRT-T = six large fields IMRT plans with jaw tracking technique; 12F-IMRT = twelve small fields IMRT plans with fixed jaw; 12F-IMRT-T = twelve small fields IMRT plans with jaw tracking technique.</p

The mean doses of organs at risk, MU, beam-on time, and mean dose rate (MDR) for treatment plans created with different planning techniques.

<p><i>Abbreviations:</i> HFF-VMAT-FF = two half-field full-arcs VMAT with conventional flattened (FF) beam; HFQ-VMAT-FF = eight half-field quarter-arcs VMAT with FF beam; HFQ-VMAT-FFF = eight half-field quarter-arcs VMAT with flattening filter free (FFF) beam.</p><p>* Body: it is the region of the CT which was scanned.</p><p>* <i>P</i> value corresponds to the paired <i>t</i> test: a = HFF-VMAT-FF vs HFQ-VMAT-FF, b = HFQ-VMAT-FF vs HFQ-VMAT-FFF.</p><p>The mean doses of organs at risk, MU, beam-on time, and mean dose rate (MDR) for treatment plans created with different planning techniques.</p

A practical method to improve the performance of knowledge-based VMAT planning for endometrial and cervical cancer

The aim of this work was to demonstrate a practical and effective method to improve the performance of RapidPlan (RP) model. 203 consecutive clinical VMAT plans (P0) for cervical and endometrial cancer were used to train an RP model (M0). The plans were then reoptimized by M0 to generate 203 new plans (P1). Compared with P0, 150 plans with a lower mean dose (MD) of bladder, rectum and PBM were selected from P1 to configure a new RP model (M1). A final RP model (M2) was trained using plans in M1 and the remaining 53 plans from P1 (excluding OARs with worse MD) and the corresponding plans from P0 (only including OARs with better MD). The models were validated on the mentioned 53 plans (closed-loop set) and 46 patient cohorts outside the training library (open-loop set). p  For closed-loop validation, the difference of D2%, D98% and CI95% between groups was of no statistical significance, the homogeneity index (HI) was lower in the groups of RP models (p 0, M1 and M2, except the MD of bowel in M1 and MD of LFH in M2. Similarly, for open-loop validation, there was no significant difference in D2%, D98% and HI between groups, but CI95% was larger in the clinical group (p 0, M1 and M2, with the exception of bowel in M1. The practical method of incorporating plan data of better-sparing OARs from both the clinical VMAT plans and the re-optimized plans could further improve the performance of the RP model.</p

Isodose distributions for one patient with esophageal cancer in four treatment plans.

6F-IMRT = six large fields IMRT plans with fixed jaw; 6F-IMRT-T = six large fields IMRT plans with jaw tracking technique; 12F-IMRT = twelve small fields IMRT plans with fixed jaw; 12F-IMRT-T = twelve small fields IMRT plans with jaw tracking technique.</p

Dosimetric parameters comparison for PTV in four treatment plans.

Dosimetric parameters comparison for PTV in four treatment plans.</p

Planning Study of Flattening Filter Free Beams for Volumetric Modulated Arc Therapy in Squamous Cell Carcinoma of the Scalp

<div><p>Purpose</p><p>Flattening filter free (FFF) beams show the potential for a higher dose rate and lower peripheral dose. We investigated the planning study of FFF beams with their role for volumetric modulated arc therapy (VMAT) in squamous cell carcinoma of the scalp.</p><p>Methods and Materials</p><p>One patient with squamous cell carcinoma which had involvement of entire scalp was subjected to VMAT using TrueBeam linear accelerator. As it was a rare skin malignancy, CT data of 7 patients with brain tumors were also included in this study, and their entire scalps were outlined as target volumes. Three VMAT plans were employed with RapidArc form: two half-field full-arcs VMAT using 6 MV standard beams (HFF-VMAT-FF), eight half-field quarter-arcs VMAT using 6 MV standard beams (HFQ-VMAT-FF), and HFQ-VMAT using FFF beams (HFQ-VMAT-FFF). Prescribed dose was 25×2 Gy (50 Gy). Plan quality and efficiency were assessed for all plans.</p><p>Results</p><p>There were no statistically significant differences among the three VMAT plans in target volume coverage, conformity, and homogeneity. For HFQ-VMAT-FF plans, there was a significant decrease by 12.6% in the mean dose to the brain compared with HFF-VMAT-FF. By the use of FFF beams, the mean dose to brain in HFQ-VMAT-FFF plans was further decreased by 7.4% compared with HFQ-VMAT-FF. Beam delivery times were similar for each technique.</p><p>Conclusions</p><p>The HFQ-VMAT-FF plans showed the superiority in dose distributions compared with HFF-VMAT-FF. HFQ-VMAT-FFF plans might provide further normal tissue sparing, particularly in the brain, showing their potential for radiation therapy in squamous cell carcinoma of the scalp.</p></div

Delineated planning target volume (PTV) for esophageal cancer in beam’s eye view (BEV) and jaw setup of IMRT plans.

(A) Jaw setup of large field IMRT plans. (B) Jaw setup of small field IMRT plans.</p

Dosimetric parameters comparison for the organs at risk: Total lung, heart, spinal cord, and spinal cord PRV.

Dosimetric parameters comparison for the organs at risk: Total lung, heart, spinal cord, and spinal cord PRV.</p

The number of monitor units (MU), beam-on time (BOT), and mean dose rate (MDR) for treatment plans created with different planning techniques.

The number of monitor units (MU), beam-on time (BOT), and mean dose rate (MDR) for treatment plans created with different planning techniques.</p

Planning Study of Flattening Filter Free Beams for Volumetric Modulated Arc Therapy in Squamous Cell Carcinoma of the Scalp - Figure 2

<p><b>The beam setup of two designs for VMAT plans in clockwise (CW):</b> (A) HFF-VMAT: two half-field full-arcs VMAT; (B) HFQ-VMAT: eight half-field quarter-arcs VMAT.</p