Application of a smart 18F-FDG-PET adaptive threshold segmentation algorithm for the biological target volume delineation in head and neck cancer.

Background: The aim of the present study is to evaluate the reliability of a F-fluorodeoxyglucose (F-FDG) PET adaptive threshold segmentation (ATS) algorithm, previously validated in a preclinical setting on several scanners, for the biological target volume (BTV) delineation of head and neck radiotherapy planning.

Methods: [18F]FDG PET ATS algorithm was studied in treatment plans of head and neck squamous cell carcinoma on a dedicated workstation (iTaRT, Tecnologie Avanzate, Turin, Italy). BTVs segmented by the present ATS algorithm (BTVATS) were compared with those manually segmented for the original radiotherapy treatment planning (BTVVIS).

Adaptive Strategy for External Beam Radiation Therapy in Prostate Cancer: Management of the Geometrical Uncertainties With Robust Optimization.

Purpose: We aim to develop and validate a new adaptive method for prostate cancer radiation therapy (RT), using an offline strategy to improve treatment personalization by modeling the internal target volume on individual basis and account for the residual set-up uncertainties by robust optimization.

Methods And Materials: Twenty patients with intermediate-high prostate cancer treated with radical radiation therapy were enrolled. The first step of the offline adaptive RT strategy is the identification of a patient-specific internal target volume based on the kV cone beam computed tomography (kV-CBCT) data sets acquired during the first 5 fractions.

Cumulative radiation dose and radiation risk from medical imaging in patients subjected to endovascular aortic aneurysm repair.

Purpose: This study was undertaken to quantify the cumulative effective dose (CED) of radiation and the dose to relevant organs in endovascular aortic repair (EVAR) patients, to assess radiation risks and to evaluate the clinical usefulness of multi-detector computed tomography (MDCT) follow-up.

Materials And Methods: The radiation exposures were obtained from 71 consecutive EVAR patients with a follow-up duration ≥1 year. Dose calculations were performed on an individual basis and expressed as effective doses and organ doses.

The relationship between quantitative perfusion and functional results and acquisition time with reduced administered activity for 99mTc tetrofosmin myocardial gated-SPECT.

Purpose: The aim of this study was to assess the relationship between administered 99mTc tetrofosmin activity in myocardial gated-SPECT and findings of myocardial perfusion and left ventricular ejection fraction (LVEF) as markers of diagnostic outcome.

Materials And Methods: Fifty-two patients with heterogeneous cardiac diseases and a clinical referral for myocardial perfusion imaging were prospectively studied. A separate-day acquisition protocol was adopted with a low fixed activity of 370 MBq, which corresponds to an average reduction of 31% with respect to the median value of 533 MBq usually administered in our laboratory.

Influence of reconstruction settings on the performance of adaptive thresholding algorithms for FDG-PET image segmentation in radiotherapy planning.

The purpose of this study was to analyze the behavior of a contouring algorithm for PET images based on adaptive thresholding depending on lesions size and target-to-background (TB) ratio under different conditions of image reconstruction parameters. Based on this analysis, the image reconstruction scheme able to maximize the goodness of fit of the thresholding algorithm has been selected. A phantom study employing spherical targets was designed to determine slice-specific threshold (TS) levels which produce accurate cross-sectional areas.