Evaluating AI-generated CBCT-based synthetic CT images for target delineation in palliative treatments of pelvic bone metastasis at conventional C-arm linacs.

Purpose: One-table treatments with treatment imaging, preparation and delivery occurring at one treatment couch, could increase patients' comfort and throughput for palliative treatments. On regular C-arm linacs, however, cone-beam CT (CBCT) imaging quality is currently insufficient. Therefore, our goal was to assess the suitability of AI-generated CBCT based synthetic CT (sCT) images for target delineation and treatment planning for palliative radiotherapy.

Technical feasibility of online adaptive stereotactic treatments in the abdomen on a robotic radiosurgery system.

Background And Purpose: Stereotactic body radiotherapy (SBRT) has been proven to be beneficial for several disease sites in the (lower) abdomen. However, the quality of the treatment plan, based on a single planning computed tomography (CT), can be compromised due to large inter-fraction motion of the target and organs at risk (OARs) in this anatomical region. The aim of this study was to investigate the feasibility of online adaptive SBRT treatments on a robotic radiosurgery system and to record estimated total treatment times.

Impact of Using Unedited CT-Based DIR-Propagated Autocontours on Online ART for Pancreatic SBRT.

Purpose: To determine the dosimetric impact of using unedited autocontours in daily plan adaptation of patients with locally advanced pancreatic cancer (LAPC) treated with stereotactic body radiotherapy using tumor tracking.

Materials And Methods: The study included 98 daily CT scans of 35 LAPC patients. All scans were manually contoured (MAN), and included the PTV and main organs-at-risk (OAR): stomach, duodenum and bowel.

Comparison of Daily Online Plan Adaptation Strategies for a Cohort of Pancreatic Cancer Patients Treated with SBRT.

Purpose: To study the trade-offs of three online strategies to adapt treatment plans of patients with locally advanced pancreatic carcinoma (LAPC) treated using the CyberKnife with tumor tracking.

Methods And Materials: A total of 35 planning computed tomography scans and 98 daily in-room computed tomography scans were collected from 35 patients with LAPC. Planned dose distributions, optimized with VOLO, were evaluated on manually contoured daily anatomies to collect daily doses.

A model-based patient selection tool to identify who may be at risk of exceeding dose tolerances during pancreatic SBRT.

Purpose: Locally advanced pancreatic cancer (LAPC) patients are prone to experience daily anatomical variations, which can lead to additional doses in organs-at-risk (OAR) during SBRT. A patient selection tool was developed to identify who may be at risk of exceeding dose tolerances, by quantifying the dosimetric impact of daily variations using an OAR motion model.

Materials And Methods: The study included 133 CT scans from 35 LAPC patients.

Pancreatic cancer treated with SBRT: Effect of anatomical interfraction variations on dose to organs at risk.

Background And Purpose: Interfraction shape and position variations of organs at risk (OARs) may increase uncertainty in dose delivery during stereotactic body radiotherapy (SBRT), potentially leading to overirradiation or concessions in planned tumor dose and/or coverage to prevent clinical constraints violation. The aim of our study was to quantitatively analyze the impact of anatomical interfraction variations on dose to OARs in pancreatic cancer (PC) treated by SBRT using a CyberKnife with integrated CT-on-rails.

Materials And Methods: Thirty-five PC patients treated with SBRT (40 Gy/5 fractions) underwent a CT-scan in treatment position before each of the first three fractions using the CT-on-rails system.

Modeling daily changes in organ-at-risk anatomy in a cohort of pancreatic cancer patients.

Purpose: To characterize daily geometrical variations of gastrointestinal organs with respect to pancreatic tumors, through a population-based statistical model.

Materials And Methods: The study included 131 CT scans from 35 pancreatic cancer patients treated with Stereotactic Body Radiotherapy (SBRT). For each patient, day-to-day anatomical variations of the stomach, the duodenum and the bowel were assessed from the deformation vector fields (DVF) obtained by non-rigidly registering the contours of the fractions to the planning CT scans.

3-D Subject-Specific Shape and Density Estimation of the Lumbar Spine From a Single Anteroposterior DXA Image Including Assessment of Cortical and Trabecular Bone.

Dual Energy X-ray Absorptiometry (DXA) is the standard exam for osteoporosis diagnosis and fracture risk evaluation at the spine. However, numerous patients with bone fragility are not diagnosed as such. In fact, standard analysis of DXA images does not differentiate between trabecular and cortical bone; neither specifically assess of the bone density in the vertebral body, which is where most of the osteoporotic fractures occur.