Photon-Counting CT in Cancer Radiotherapy: Technological Advances and Clinical Benefits.

Photon-counting computed tomography (PCCT) marks a significant advancement over conventional energy-integrating detector (EID) CT systems. This review highlights PCCT's superior spatial and contrast resolution, reduced radiation dose, and multi-energy imaging capabilities, which address key challenges in radiotherapy, such as accurate tumor delineation, precise dose calculation, and treatment response monitoring. PCCT's improved anatomical clarity enhances tumor targeting while minimizing damage to surrounding healthy tissues.

Improving access in medical physics residency programs for physicists with disabilities.

Within the landscape of medical physics education, residency programs are instrumental in imparting hands-on training and experiential knowledge to early-career physicists. Ensuring access to educational opportunities for physicists with disabilities is a legal, ethical, and pragmatic requirement for programs, considering that a significant proportion of the United States population has a disability. Grounded in conceptual frameworks of competency-based medical education and the social model of disability, this work provides an introduction to some practical recommendations for medical physics residency programs.

NRG Oncology Assessment of Artificial Intelligence Deep Learning-Based Auto-segmentation for Radiation Therapy: Current Developments, Clinical Considerations, and Future Directions.

Deep learning neural networks (DLNN) in Artificial intelligence (AI) have been extensively explored for automatic segmentation in radiotherapy (RT). In contrast to traditional model-based methods, data-driven AI-based models for auto-segmentation have shown high accuracy in early studies in research settings and controlled environment (single institution). Vendor-provided commercial AI models are made available as part of the integrated treatment planning system (TPS) or as a stand-alone tool that provides streamlined workflow interacting with the main TPS.

Intra-operative Radiation Therapy for Colorectal or Anal Cancer at Risk for Margin-Positive Resection: Initial Results of a Single-Institution Registry.

Purpose: Pelvic recurrence of rectal or anal cancers is associated with considerable morbidity and mortality. We report our initial experience with an aggressive intra-operative radiotherapy (IORT) program.

Methods: Patients with locally advanced or recurrent rectal or anal cancers considered to have a high likelihood of R1 or R2 resection after multi-disciplinary review underwent surgical excision and IORT using a high-dose-rate afterloader (Ir-192) and HAM applicator.

Toward understanding deep learning classification of anatomic sites: lessons from the development of a CBCT projection classifier.

Deep learning (DL) applications strongly depend on the training dataset and convolutional neural network architecture; however, it is unclear how to objectively select such parameters. We investigate the classification performance of different DL models and training schemes for the anatomic classification of cone-beam computed tomography (CBCT) projections. CBCT scans from 1055 patients were collected and manually classified into five anatomic classes and used to develop DL models to predict the anatomic class from single x-ray projections.

AAPM task group report 302: Surface-guided radiotherapy.

The clinical use of surface imaging has increased dramatically, with demonstrated utility for initial patient positioning, real-time motion monitoring, and beam gating in a variety of anatomical sites. The Therapy Physics Subcommittee and the Imaging for Treatment Verification Working Group of the American Association of Physicists in Medicine commissioned Task Group 302 to review the current clinical uses of surface imaging and emerging clinical applications. The specific charge of this task group was to provide technical guidelines for clinical indications of use for general positioning, breast deep-inspiration breath hold treatment, and frameless stereotactic radiosurgery.

Evaluation of Dose Distribution to Organs-at-Risk in a Prospective Phase 1 Trial of Pembrolizumab and Multisite Stereotactic Body Radiation Therapy (SBRT).

Purpose: Our purpose was to characterize the radiation doses to organs-at-risk (OAR) in the phase I trial (NCT02608385) that established safety/efficacy of stereotactic body radiation therapy (SBRT) using NRG-BR001 dose constraints combined with programmed cell death protein 1 blockade for metastatic disease.

Methods And Materials: Between January 2016 and May 2018, 73 patients with advanced solid tumors were treated with SBRT followed by pembrolizumab. Tumor volumes (gross tumor volume/internal tumor volume) were delineated for each metastasis, with planning target volume contraction to limit OAR dose per protocol (n = 54) or when gross tumor volume/internal tumor volume > 65 cm (n = 19).

A framework for automated and streamlined kV cone beam computed tomography image quality assurance: a multi-institutional study.

The purpose of this study was to develop and evaluate a framework to support automated standardized testing and analysis of Cone Beam Computed Tomography (CBCT) image quality QA across multiple institutions. A survey was conducted among the participating institutions to understand the variability of the CBCT QA practices. A commercial, automated software platform was validated by seven institutions participating in a consortium dedicated to automated quality assurance.

A Phase 1 Trial of Concurrent or Sequential Ipilimumab, Nivolumab, and Stereotactic Body Radiotherapy in Patients With Stage IV NSCLC Study.

Introduction: Previous studies have evaluated stereotactic body radiotherapy (SBRT) in oligometastatic patients with NSCLC, including multimodality treatment with anti-programmed cell death protein-1 monotherapy. Questions remain regarding the timing of SBRT and immunotherapy, safety with dual checkpoint blockade, and the utility in widely metastatic patients. This randomized phase 1 trial combined nivolumab and ipilimumab with sequential or concurrent multisite SBRT in patients with stage IV NSCLC to evaluate safety and obtain preliminary activity data.

The role of surface-guided radiation therapy for improving patient safety.

Emerging data indicates SGRT could improve safety and quality by preventing errors in its capacity as an independent system in the treatment room. The aim of this work is to investigate the utility of SGRT in the context of safety and quality. Three incident learning systems (ILS) were reviewed to categorize and quantify errors that could have been prevented with SGRT: SAFRON (International Atomic Energy Agency), UW-ILS (University of Washington) and AvIC (Skåne University Hospital).

Development of a neonate X-ray phantom for 2D imaging applications using single-tone inkjet printing.

Purpose: Inkjet printers can be used to fabricate anthropomorphic phantoms by the use of iodine-doped ink. However, challenges persist in implementing this technique. The calibration from grayscale to ink density is complex and time-consuming.

AAPM medical physics practice guideline 3.b.: Levels of supervision for medical physicists in clinical training.

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States.

Evaluation of Safety of Stereotactic Body Radiotherapy for the Treatment of Patients With Multiple Metastases: Findings From the NRG-BR001 Phase 1 Trial.

Importance: Stereotactic body radiotherapy (SBRT) for oligometastases is hypothesized to improve survival and is increasingly used. Little evidence supports its safe use to treat patients with multiple metastases.

Objective: To establish safety of SBRT dose schedules in patients with 3 to 4 metastases or 2 metastases in close proximity to each other.

A study of the dosimetric impact of daily setup variations measured with cone-beam CT on three-dimensional conformal radiotherapy for early-stage breast cancer delivered in the prone position.

Purpose: To evaluate the dosimetric impact of daily positioning variations measured with cone-beam computed tomography (CBCT) on whole-breast radiotherapy patients treated in the prone position.

Methods: Daily CBCT was prospectively acquired for 30 consecutive patients positioned prone. Treatment for early-stage (≤II) breast cancer was prescribed with standard dose (50 Gy/25 fractions) or hypofractionation (42.

Harmonization of radiomic feature variability resulting from differences in CT image acquisition and reconstruction: assessment in a cadaveric liver.

Studies investigating the effects of computed tomography (CT) image acquisition and reconstruction parameters have mostly been limited to non-human phantoms to limit exposure to patients. This study investigates these variations using a cadaveric liver and determines harmonization methods to mitigate these variations. A reference CT scan of a cadaveric liver was acquired along with 16 modified scans.

Clinical paradigms and challenges in surface guided radiation therapy: Where do we go from here?

Surface guided radiotherapy (SGRT) is becoming a routine tool for patient positioning for specific clinical sites in many clinics. However, it has not yet gained its full potential in terms of widespread adoption. This vision paper first examines some of the difficulties in transitioning to SGRT before exploring the current and future role of SGRT alongside and in concert with other imaging techniques.

Physician review of image registration and normal structure delineation.

Introduction: Image registration and delineation of organs at risk (OARs) are key components of three-dimensional conformal (3DCRT) and intensity-modulated radiotherapy (IMRT) treatment planning. This study hypothesized that image registration and OAR delineation are often performed by medical physicists and/or dosimetrists and are not routinely reviewed by treating physicians.

Methods: An anonymous, internet-based survey of medical physicists and dosimetrists was distributed via the MEDPHYS and MEDDOS listserv groups.

Effects of variability in radiomics software packages on classifying patients with radiation pneumonitis.

While radiomics feature values can differ when extracted using different radiomics software, the effects of these variations when applied to a particular clinical task are currently unknown. The goal of our study was to use various radiomics software packages to classify patients with radiation pneumonitis (RP) and to quantify the variation in classification ability among packages. A database of serial thoracic computed tomography scans was obtained from 105 patients with esophageal cancer.