Determination of dose-response calibration curves for gamma radiation using gamma-H2AX immunofluorescence based biodosimetry.

Background: Gamma-H2AX immunofluorescence assay has gained popularity as a DNA double strand break marker. In this work, we have investigated the potential use of gamma H2AX immunofluorescence assay as a biological dosimeter for estimation of dose in our institution.

Materials And Methods: Seven healthy individuals were selected for the study and the blood samples collected from the first five individuals were irradiated to low doses (0-10 cGy) and high doses (50-500 cGy) in a telecobalt unit.

Multi-centre radiomics for prediction of recurrence following radical radiotherapy for head and neck cancers: Consequences of feature selection, machine learning classifiers and batch-effect harmonization.

Background And Purpose: Radiomics models trained with limited single institution data are often not reproducible and generalisable. We developed radiomics models that predict loco-regional recurrence within two years of radiotherapy with private and public datasets and their combinations, to simulate small and multi-institutional studies and study the responsiveness of the models to feature selection, machine learning algorithms, centre-effect harmonization and increased dataset sizes.

Materials And Methods: 562 patients histologically confirmed and treated for locally advanced head-and-neck cancer (LA-HNC) from two public and two private datasets; one private dataset exclusively reserved for validation.

A strategy to determine off-axis dosimetric leaf gap using OSLD and EPID.

Background: The aim of the study was to investigate the dosimetric feasibility of using optically stimulated luminescence dosimeters (OSLD) and an electronic portal imaging device (EPID) for central axis (CA X) and off-axis (OAX) dosimetric leaf gap (DLG) measurement.

Materials And Methods: The Clinac 2100C/D linear accelerator equipped with Millennium-120 multileaf collimator (MLC) and EPID was utilized for this study. The DLG values at CA X and ± 1 cm OAX (1 cm superior and inferior to the CA X position, respectively along the plane perpendicular to MLC motion) were measured using OSLD (DLG) and validated using ionization chamber dosimetry (DLG).

Dosimetric and clinical advantages of adapting the DIBH technique to hybrid solitary dynamic portal radiotherapy for left-sided chest-wall plus regional nodal irradiation.

To evaluate the dosimetric and clinical advantages of using deep-inspiration breath-hold (DIBH) technique in hybrid solitary dynamic portal radiotherapy (hSDPRT) for left-sided chest-wall plus regional nodal irradiation and to demonstrate a simplified strategy for preclinical commissioning and calibration of DIBH-gating technique. Fifteen patients with left-sided breast cancer who underwent postmastectomy radiotherapy using hSDPRT were retrospectively evaluated. Two sets of planning-CT images were acquired for each patient, one with free/normal breathing and the other with DIBH.

A new strategy for craniospinal axis localization and adaptive dosimetric evaluation using cone beam CT.

Background And Aim: Computational complexities encountered in craniospinal irradiation (CSI) have been widely investigated with different planning strategies. However, localization of the entire craniospinal axis (CSA) and evaluation of adaptive treatment plans have traditionally been ignored in CSI treatment. In this study, a new strategy for CSI with comprehensive CSA localization and adaptive plan evaluation has been demonstrated using cone beam CT with extended longitudinal field-of-view (CBCT).

A rationale for cone beam CT with extended longitudinal field-of-view in image guided adaptive radiotherapy.

Purpose: To investigate the efficacy of using cone beam CT with extended longitudinal field-of-view (CBCT) for image guided adaptive radiotherapy (IGART).

Methods: The protocol acquires two CBCT scans with a linear translation of treatment couch in the patient plane, allowing a 1 cm penumbral overlap (i.e.