Transformation of Physical DVHs to Radiobiologically Equivalent Ones in Hypofractionated Radiotherapy Analyzing Dosimetric and Clinical Parameters: A Practical Approach for Routine Clinical Practice in Radiation Oncology

Abstract

Purpose. The purpose of this study was to transform DVHs from physical to radiobiological ones as well as to evaluate their reliability by correlations of dosimetric and clinical parameters for 50 patients with prostate cancer and 50 patients with breast cancer, who were submitted to Hypofractionated Radiotherapy. Methods and Materials. To achieve this transformation, we used both the linear-quadratic model (LQ model) and the Niemierko model. The outcome of radiobiological DVHs was correlated with acute toxicity score according to EORTC/RTOG criteria. Results. Concerning the prostate radiotherapy, there was a significant correlation between RTOG acute rectal toxicity and D 50 (P < 0.001) and V 60 (P = 0.001) dosimetric parameters, calculated for α/β = 10 Gy. Moreover, concerning the breast radiotherapy there was a significant correlation between RTOG skin toxicity and V ≥60 dosimetric parameter, calculated for both α/β = 2.3 Gy (P < 0.001) and α/β = 10 Gy (P < 0.001). The new tool seems reliable and user-friendly. Conclusions. Our proposed model seems user-friendly. Its reliability in terms of agreement with the presented acute radiation induced toxicity was satisfactory. However, more patients are needed to extract safe conclusions.

A Retrospective Analysis of Toxicity and Efficacy for 2 Hypofractionated Irradiation Schedules Versus a Conventional One for Post-Mastectomy Adjuvant Radiotherapy in Breast Cancer

“…Patient setup was monitored weekly using portal films. The transformation of physical to radiobiological dose volume histograms for normal tissues was performed with the Niemierko model according to Thrapsanioti et al [12]. All patients were treated on a VARIAN CLINAC 600C or SIEMENS Oncore or ELECTA SL-75 linear accelerator, with 6 MV photon beams.…”

Is Locally Advanced Head-Neck Cancer One More Candidate for Accelerated Hypofractionation?

“…In terms of dosimetry, for dose constrains in OARs, we used the QUANTEC criteria adapted for head and neck treatment (11,12). In order to assess the biological dose in critical organs according to QUANTEC, all relevant Dose Volume Histograms DVHs derived from the hypofractionated schedules representing OARs were transformed into equivalent histograms by using a Niemierko model as described in a previous publication (13).…”