Maddalena Mambretti1, Chiara Romanò2, Giulia Marvaso3, Stefania Comi4, Raffaella Cambria4, Delia Ciardo3, Francesca Emiro2, Cristiana Fodor3, Dario Zerini3, Giulia Riva5, Giuseppe Petralia6, Ottavio De Cobelli7, R Orecchia8, Federica Cattani4, Barbara Alicja Jereczek-Fossa5. 1. Department of Radiotherapy, European Institute of Oncology, Milan, Italy. Electronic address: maddy.mambretti@gmail.com. 2. Department of Physics, University of Milan, Italy; Unit of Medical Physics, European Institute of Oncology, Milan, Italy. 3. Department of Radiotherapy, European Institute of Oncology, Milan, Italy. 4. Unit of Medical Physics, European Institute of Oncology, Milan, Italy. 5. Department of Radiotherapy, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-oncology, University of Milan, Italy. 6. Department of Radiology, European Institute of Oncology, Milan, Italy. 7. Department of Urology, European Institute of Oncology, Milan, Italy. 8. Scientific Directorate, European Institute of Oncology, Milan, Italy.
Abstract
PURPOSE: Formulation of a global Unified Dosimetry Index (gUDI) for the evaluation of prostate simultaneous integrated boost Volumetric Modulated Arc Therapy (VMAT by RapidArc) radiotherapy plans. METHODS AND MATERIALS: Dose coverage, conformity, homogeneity and dose gradient index could be included in the Unified Dosimetry Index (UDI). We developed a global UDI to evaluate treatment plans containing volumes irradiated with different dose prescriptions: Intensity Modulated Radiation Therapy with simultaneous integrated boost (IMRT-SIB) with 2 dose levels (36.25 Gy/5 fz for the whole prostate gland and 37.5 Gy/5 fz for Dominant Intraprostatic Lesion (DIL)). To validate gUDI scoring system, 65 prostate cancer patients were evaluated. Mean (µ) and standard deviations (σ) were calculated for all dosimetry indices and gUDI. Furthermore, gUDI µ and σ were analyzed to compare and classify treatment plans: plans can be ranked as "excellent", "good", "average" or "poor". RESULTS: Prostate Dose Gradient, Prostate Conformity and DIL Conformity indices had highlighted a major deviation from ideal scores. gUDI index classification showed most of the plans scored as "average" and "good". CONCLUSION: gUDI score can be a useful tool to quantify treatment plans quality also when volumes with different dose-prescription are treated.
PURPOSE: Formulation of a global Unified Dosimetry Index (gUDI) for the evaluation of prostate simultaneous integrated boost Volumetric Modulated Arc Therapy (VMAT by RapidArc) radiotherapy plans. METHODS AND MATERIALS: Dose coverage, conformity, homogeneity and dose gradient index could be included in the Unified Dosimetry Index (UDI). We developed a global UDI to evaluate treatment plans containing volumes irradiated with different dose prescriptions: Intensity Modulated Radiation Therapy with simultaneous integrated boost (IMRT-SIB) with 2 dose levels (36.25 Gy/5 fz for the whole prostate gland and 37.5 Gy/5 fz for Dominant Intraprostatic Lesion (DIL)). To validate gUDI scoring system, 65 prostate cancerpatients were evaluated. Mean (µ) and standard deviations (σ) were calculated for all dosimetry indices and gUDI. Furthermore, gUDI µ and σ were analyzed to compare and classify treatment plans: plans can be ranked as "excellent", "good", "average" or "poor". RESULTS: Prostate Dose Gradient, Prostate Conformity and DIL Conformity indices had highlighted a major deviation from ideal scores. gUDI index classification showed most of the plans scored as "average" and "good". CONCLUSION: gUDI score can be a useful tool to quantify treatment plans quality also when volumes with different dose-prescription are treated.