Feasibility of Gold Fiducial Markers as a Surrogate for Gross Tumor Volume Position in Image-Guided Radiation Therapy of Rectal Cancer

Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas

Predictive factors for response and toxicity after brachytherapy for rectal cancer; results from the HERBERT study

Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Reducing uncertainties in image-guided radiotherapy of rectal cancer

Improvements in the treatment of rectal cancer patients have led to increased survival. Therefore, long-term outcome has become an increasingly important factor. Both neoadjuvant (chemo)radiotherapy and total mesorectal excision surgery are associated with toxicity. As a result, research for rectal cancer treatment has focused on the reduction of radiation dose to healthy tissue and less extensive surgery or omission of surgery in selected patients. The work described in this thesis can be used to reduce uncertainties related to image-guided external beam radiotherapy (EBRT) and high-dose-rate endorectal brachytherapy (HDREBT) of rectal cancer. By decreasing treatment related uncertainties, dose to surrounding healthy tissue can be reduced and/or a higher dose to the target volume can be delivered with an isotoxic effect. The MRI visibility of four types of fiducial markers as a surrogate for gross tumor volume (GTV) location was evaluated. In addition, it was found that the use of fiducial markers as a surrogate for GTV location in an EBRT GTV boost setting allows smaller treatment margins. For HDREBT, it was found that daily CT imaging should be the minimal standard to verify a correct applicator setup. In addition, we propose the use of an ultrashort echo time MRI sequence to visualize the applicator on MRI. Lastly, we determined the added value of a national study group meeting on the quality and variability of EBRT treatment plans for the introduction of a novel target volume that includes only the mesorectum.</p

Francia e Italia. Evoluzione dei sistemi politici

Quaderni della Fondazione Adriano Olivetti ; 4

Applicator visualization using ultrashort echo time MRI for high-dose-rate endorectal brachytherapy

PURPOSE: The individual channels in an endorectal applicator for high-dose-rate endorectal brachytherapy are not visible on standard MRI sequences. The aim of this study was to test whether an ultrashort echo time (UTE) MRI sequence could be used to visualize the individual channels to enable MR-only treatment planning for rectal cancer.METHODS AND MATERIALS: We used a radial three-dimensional (3D) UTE pulse sequence and acquired images of phantoms and two patients with rectal cancer. We rigidly registered a UTE image and CT scan of an applicator phantom, based on the outline of the applicator. One observer compared channel positions on the UTE image and CT scan in five slices spaced 25 mm apart. To quantify geometric distortions, we scanned a commercial 3D geometric quality assurance phantom and calculated the difference between detected marker positions on the UTE image and corresponding marker positions on two 3D T-1-weighted images with opposing readout directions.RESULTS: On the UTE images, there is sufficient contrast to discern the individual channels. The difference in channel positions on the UTE image compared with the CT was on average -0.1 +/- 0.1 mm (left-right) and 0.1 +/- 0.3 mm (anteroposterior). After rigid registration to the 3D T-1-weighted sequences, the residual 95th percentile of the geometric distortion inside a 550-mm-diameter sphere was 1.0 mm (left-right), 0.9 mm (anteroposterior), and 0.9 mm (craniocaudal).CONCLUSIONS: With a UTE sequence, the endorectal applicator and individual channels can be adequately visualized in both phantom and patients. The geometrical fidelity is within an acceptable range. (C) 2020 The Authors. Published by Elsevier Inc. on behalf of American Brachytherapy Society

Benefit of adaptive CT-based treatment planning in high-dose-rate endorectal brachytherapy for rectal cancer

Biological, physical and clinical aspects of cancer treatment with ionising radiatio

Benefit of repeat CT in high-dose rate brachytherapy as radical treatment for rectal cancer

Biological, physical and clinical aspects of cancer treatment with ionising radiatio

Benefit of repeat CT in high-dose rate brachytherapy as radical treatment for rectal cancer

Biological, physical and clinical aspects of cancer treatment with ionising radiatio

MRI visibility of gold fiducial markers for image-guided radiotherapy of rectal cancer

Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas