Encrypted login | home

Program Information

Comprehensive Commissioning and Validation of Transport Based Dose Computation for Stereotactic Body Radiation Therapy (SBRT)

V Rodriguez

V Rodriguez1*, F Reynoso2 , R Morris3 , M Reilly4 , R Kashani5 , P McGeachy6 , R Zavan7 , R Khan8 , (1) Washington University School of Medicine, St. Louis, MO, (2) Washington University School of Medicine, St. Louis, MO, (3) Washington University School of Medicine, St Louis, MO, (4) Washington University School of Medicine, St. Louis, MO, (5) University of Michigan, Ann Arbor, MI, (6) CancerCare Manitoba, Winnipeg, MB, (7) Universidade de Sao Paulo, Sao Paulo, Sao Paulo, (8) Washington University School of Medicine, St Louis, MO


SU-I-GPD-T-594 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To commission the transport-based dose algorithm, AcurosXB (AXB) through clinically relevant phantom measurements with a focus on SBRT-based dose calculations.

Methods: Two 6MV photon beams for a Varian TrueBeam™ were modeled in Eclipse™ Vs. 13.6.15 at two different institutions. Dose was computed using AXB for a range of field sizes (2x2cm² through 10x10cm²). Dosimetric comparisons (AXB vs. experimental measurement) were performed for 5 different phantom configurations. Configuration-A: 30×30×20cm³ Solidwater (SW) phantom; Configuration-B: Alternating SW and Styrofoam slabs; Configuration-C: A central 6x6x6cm³ acrylic “target” surrounded by cork, embedded within a water-filled acrylic shell. Ion chamber (IC) and radiographic film measurements were performed for these phantoms. Various sized square and elongated fields were evaluated for anterior, parallel opposed laterals, and 4field box beam arrangements. IMRT and VMAT test plans were also delivered for configuration C. Configuration-D: 30×30×11.4cm³ SW setup with insert for interchangeable 3D printed polystyrene slab. Measurements were performed with six different; low-density slabs (0.23 g/cm3 to 0.68 g/cm3) Configuration-E: 30×30×16.2cm³ SW containing three, 3D printed low-density slabs (0.51, 0.68 and 0.23 g/cm3). EBT3 film measurements were performed with these phantoms. Point doses, profiles and dose planes generated from AXB were compared with corresponding measurements from IC, EBT3 and radiographic films. Gamma analysis was used to quantify dosimetric agreement between film measurements and AXB dose plane calculations.

Results: 44 out of 54 IC comparisons resulted in agreement to within 2% of measurements. 3 points deviated larger than 3% from measuremented primarily due to the location of the points in reference to field dose. Radiographic films resulted in >90% gamma at 3%/3mm. EBT3 film and AXB calculation agreed to within >95% for all fields and phantoms.

Conclusion: AcurosXB is in good agreement with the experimental measurements for various materials and field sizes including the small field sizes typical of SBRT treatments.

Contact Email: