AIM: The aim of this study was to determine the Inflection Points (IPs) of flattening filter free (FFF) CyberKnife dose profiles for cone-based streotactic radiotherapy. In addition, dosimetric field sizes were determined. BACKGROUND: The increased need for treatment in the early stages of cancer necessitated the treatment of smaller tumors. However, efforts in that direction required the modeling accuracy of the beam. Removal of the flattening filter (FF) from the path of x-ray beam has provided the solution to those efforts, but required a different normalization approach for the beam to ensure the delivery of the dose accurately. As a solution, researchers proposed a normalization factor based on IPs. MATERIALS AND METHODS: Measurements using microDiamond (PTW 60019), Diode SRS (PTW 60018) and Monte Carlo (MC) calculations of dose profiles were completed at SAD 80 cm and 5 cm depth for 15-60 mm cones. Performance analysis of detectors with respect to MC calculation was carried out. Gamma evaluation method was used to determine achievable acceptability criteria for FFF CyberKnife beams. RESULTS: Acceptability within (3%-0.5 mm) was found to be anachievable criterion for all dose profile measurements of the cone beams used in this study. To determine the IP, the first and second derivatives of the dose profile were determined via the cubic spline interpolation technique. CONCLUSION: Derivatives of the interpolated profiles showed that locations of IPs and 50% isodose points coincide.
AIM: The aim of this study was to determine the Inflection Points (IPs) of flattening filter free (FFF) CyberKnife dose profiles for cone-based streotactic radiotherapy. In addition, dosimetric field sizes were determined. BACKGROUND: The increased need for treatment in the early stages of cancer necessitated the treatment of smaller tumors. However, efforts in that direction required the modeling accuracy of the beam. Removal of the flattening filter (FF) from the path of x-ray beam has provided the solution to those efforts, but required a different normalization approach for the beam to ensure the delivery of the dose accurately. As a solution, researchers proposed a normalization factor based on IPs. MATERIALS AND METHODS: Measurements using microDiamond (PTW 60019), Diode SRS (PTW 60018) and Monte Carlo (MC) calculations of dose profiles were completed at SAD 80 cm and 5 cm depth for 15-60 mm cones. Performance analysis of detectors with respect to MC calculation was carried out. Gamma evaluation method was used to determine achievable acceptability criteria for FFF CyberKnife beams. RESULTS: Acceptability within (3%-0.5 mm) was found to be anachievable criterion for all dose profile measurements of the cone beams used in this study. To determine the IP, the first and second derivatives of the dose profile were determined via the cubic spline interpolation technique. CONCLUSION: Derivatives of the interpolated profiles showed that locations of IPs and 50% isodose points coincide.
Authors: A S Shiu; S Tung; K R Hogstrom; J W Wong; R L Gerber; W B Harms; J A Purdy; R K Ten Haken; D L McShan; B A Fraass Journal: Med Phys Date: 1992 May-Jun Impact factor: 4.071
Authors: Steve B Jiang; Greg C Sharp; Toni Neicu; Ross I Berbeco; Stella Flampouri; Thomas Bortfeld Journal: Phys Med Biol Date: 2006-01-25 Impact factor: 3.609
Authors: T Kairn; A Asena; P H Charles; B Hill; C M Langton; N D Middlebrook; R Moylan; J V Trapp Journal: Australas Phys Eng Sci Med Date: 2015-05-30 Impact factor: 1.430