Chromatic bleaching and fractionation effects on optically stimulated luminescent dosimeter reuse.

Background: Optically stimulated luminescent dosimeters (OSLDs) can be bleached and reused, but questions remain about the effects of repeated bleaching and fractionation schedules on OSLD performance.

Purpose: The aim of this study was to investigate how light sources with different wavelengths and different fractionation schemes affect the performance of reused OSLDs.

Methods: OSLDs (N = 240) were irradiated on a cobalt-60 beam in different step sizes until they reached an accumulated dose of 50 Gy.

Determining Combined Modality Dosimetric Constraints by Integration of IMRT and LDR Prostate Brachytherapy Dosimetry and Correlation with Toxicity.

Purpose: Intermediate- and high-risk prostate cancer patients undergoing combination external beam radiation therapy (EBRT) and low dose rate (LDR) brachytherapy have demonstrated increased genitourinary (GU) toxicity. We have previously demonstrated a method to combine EBRT and LDR dosimetry. In this work, we use this technique for a sample of patients with intermediate- and high-risk prostate cancer, correlate with clinical toxicity, and suggest preliminary summed organ-at-risk constraints for future investigation.

Integrating external beam and prostate seed implant dosimetry for intermediate and high-risk prostate cancer using biologically effective dose: Impact of image registration technique.

Purpose: Combining external beam radiation therapy (EBRT) and prostate seed implant (PSI) is efficacious in treating intermediate- and high-risk prostate cancer at the cost of increased genitourinary toxicity. Accurate combined dosimetry remains elusive due to lack of registration between treatment plans and different biological effect. The current work proposes a method to convert physical dose to biological effective dose (BED) and spatially register the dose distributions for more accurate combined dosimetry.

Assessing initial plan check efficacy using TG 275 failure modes and incident reporting.

Plan checks are important components of a robust quality assurance (QA) program. Recently, the American Association of Physicists in Medicine (AAPM) published two reports concerning plan and chart checking, Task Group (TG) 275 and Medical Physics Practice Guideline (MPPG) 11.A.

Biological effective dose in analysis of rectal dose in prostate cancer patients who underwent a combination therapy of VMAT and LDR with hydrogel spacer insertion.

This study aimed to evaluate rectal dose reduction in prostate cancer patients who underwent a combination of volumetric modulated arc therapy (VMAT) and low-dose-rate (LDR) brachytherapy with insertion of hydrogel spacer (SpaceOAR). For this study, 35 patients receiving hydrogel spacer and 30 patients receiving no spacer were retrospectively enrolled. Patient was treated to doses of 45 Gy to the primary tumor site and nodal regions over 25 fractions using VMAT and 100 Gy to the prostate using prostate seed implant (PSI).

Cardiotoxicity screening of long-term, breast cancer survivors-The CAROLE (Cardiac-Related Oncologic Late Effects) Study.

Background: Long-term breast cancer survivors are at risk for cardiotoxicity after treatment, but there is insufficient evidence to provide long-term (~10 years) cardiovascular disease (CVD) screening recommendations. We sought to evaluate a tri-modality CVD screening approach.

Methods: This single-arm, feasibility study enrolled 201 breast cancer patients treated ≥6 years prior without CVD at diagnosis.

Development and execution of a pandemic preparedness plan: Therapeutic medical physics and radiation dosimetry during the COVID-19 crisis.

The SARS-CoV-2 coronavirus pandemic has spread around the world including the United States. New York State has been hardest hit by the virus with over 380 000 citizens with confirmed COVID-19, the illness associated with the SARS-CoV-2 virus. At our institution, the medical physics and dosimetry group developed a pandemic preparedness plan to ensure continued operation of our service.

Impact of stereotactic body radiation therapy on geriatric assessment and management for older patients with head and neck cancer using G8.

Purpose: Management of head and neck cancers (HNC) in older adults is a common but challenging clinical scenario. We assess the impact of Stereotactic Body Radiation Therapy (SBRT) on survival utilizing the Geriatric-8 (G8) questionnaire.

Materials And Methods: 171 HNC patients, deemed medically unfit for definitive treatment, were treated with SBRT ± systemic therapy.

A Model-Based Method for Assessment of Salivary Gland and Planning Target Volume Dosimetry in Volumetric-Modulated Arc Therapy Planning on Head-and-Neck Cancer.

This study examined the relationship of achievable mean dose and percent volumetric overlap of salivary gland with the planning target volume (PTV) in volumetric-modulated arc therapy (VMAT) plan in radiotherapy for a patient with head-and-neck cancer. The aim was to develop a model to predict the viability of planning objectives for both PTV coverage and organs-at-risk (OAR) sparing based on overlap volumes between PTVs and OARs, before the planning process. Forty patients with head-and-neck cancer were selected for this retrospective plan analysis.

Quality of Life Outcomes Following Organ-Sparing SBRT in Previously Irradiated Recurrent Head and Neck Cancer.

Unlabelled: To present a retrospective analysis of the efficacy, toxicity, and quality of life (QoL) of patients treated with OAR -sparing stereotactic body radiotherapy (SBRT) in previously-irradiated head and neck cancer. From 11/2012 to 7/2015, 60 patients with in-field recurrence of head and neck cancer underwent re-irradiation with SBRT. Retreatment sites included the aerodigestive tract (43%), lateral neck (22%), and skull base (35%).

Dosimetric impact of placement errors in optically stimulated luminescent dosimetry in radiotherapy.

Introduction: Studies have suggested that optically stimulated luminescent dosimeters (OSLDs) can be used for dosimetry of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Clinical uncertainties such as placement error have not been thoroughly investigated. The purpose of this work was to measure OSLD placement error in a clinical sample and analyze its dosimetric impact.

Impact of Multi-Institutional Prospective Peer Review on Target and Organ-at-Risk Delineation in Radiation Therapy.

Purpose: Peer review is an essential component of quality assurance programs in radiation oncology. The purpose of this work was to assess whether peer reviewers recommend expansion or reduction of planning target volumes (PTVs) and organs at risk (OARs) in prospective multidisciplinary daily contour rounds.

Methods And Materials: The peer group evaluated the appropriateness of PTVs and OARs for each case according to evidence-based departmental directives.

Reducing seed waste and increasing value of dynamic intraoperative implantation of Pd-103 seeds in prostate brachytherapy.

Several nomograms exist for ordering palladium-103 seeds for permanent prostate seed implants (PSI). Excess seeds from PSIs pose additional radiation safety risks and increase the cost of care. This study compared five nomograms to clinical data from dynamic modified-peripheral intraoperative PSI to determine (a) the cause of excess seeds and (b) the optimal nomogram for our institution.

Hippocampal-sparing and target volume coverage in treating 3 to 10 brain metastases: A comparison of Gamma Knife, single-isocenter VMAT, CyberKnife, and TomoTherapy stereotactic radiosurgery.

Purpose: Our purpose was to evaluate hippocampal doses and target volume coverage with and without hippocampal sparing when treating multiple brain metastases using various stereotactic radiosurgery (SRS) platforms.

Methods And Materials: We selected 10 consecutive patients with 14 separate treatments who had been treated in our department for 3 to 10 brain metastases and added hippocampal avoidance contours. All 14 treatments were planned with GammaPlan for Gamma Knife, Eclipse for single isocenter volumetric modulated arc therapy (VMAT), TomoTherapy Treatment Planning System (TPS) for TomoTherapy, and MultiPlan for CyberKnife.

In vivo dosimetry with optically stimulated luminescent dosimeters for conformal and intensity-modulated radiation therapy: A 2-year multicenter cohort study.

Purpose: Optically stimulated luminescent dosimeters (OSLDs) are utilized for in vivo dosimetry (IVD) of modern radiation therapy techniques such as intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). Dosimetric precision achieved with conventional techniques may not be attainable. In this work, we measured accuracy and precision for a large sample of clinical OSLD-based IVD measurements.

Deformable image registration and interobserver variation in contour propagation for radiation therapy planning.

Deformable image registration (DIR) and interobserver variation inevitably intro-duce uncertainty into the treatment planning process. The purpose of the current work was to measure deformable image registration (DIR) errors and interobserver variability for regions of interest (ROIs) in the head and neck and pelvic regions. Measured uncertainties were combined to examine planning margin adequacy for contours propagated for adaptive therapy and to assess the trade-off of DIR and interobserver uncertainty in atlas-based automatic segmentation.

Defining internal target volume using positron emission tomography for radiation therapy planning of moving lung tumors.

Substantial disagreement exists over appropriate PET segmentation techniques for non-small cell lung cancer. Currently, no segmentation algorithm explicitly considers tumor motion in determining tumor borders. We developed an automatic PET segmentation model as a function of target volume, motion extent, and source-to-background ratio (the VMSBR model).

Incident Learning and Failure-Mode-and-Effects-Analysis Guided Safety Initiatives in Radiation Medicine.

By combining incident learning and process failure-mode-and-effects-analysis (FMEA) in a structure-process-outcome framework we have created a risk profile for our radiation medicine practice and implemented evidence-based risk-mitigation initiatives focused on patient safety. Based on reactive reviews of incidents reported in our departmental incident-reporting system and proactive FMEA, high safety-risk procedures in our paperless radiation medicine process and latent risk factors were identified. Six initiatives aimed at the mitigation of associated severity, likelihood-of-occurrence, and detectability risks were implemented.

New weighted maximum-intensity-projection images from cine CT for delineation of the lung tumor plus motion.

Purpose: In treatment planning of the lung tumor with 4D-CT, maximum-intensity-projection (MIP) images have been used for delineation of the gross tumor volume plus motion or iGTV, which can then be revised with the multiple phases of the 4D-CT images. Although majority of contouring can be performed with MIP, the MIP images are not recommended for delineation of iGTV if the tumor is near or connected to the diaphragm or other structures of a similar density due to insufficient contrast between the tumor and the surrounding tissues in the MIP images. To remedy this shortcoming, the authors developed a new weighted MIP (wMIP) from cine CT without respiratory gating for contouring the iGTV.

Comparative dosimetry of volumetric modulated arc therapy and limited-angle static intensity-modulated radiation therapy for early-stage larynx cancer.

To compare relative carotid and normal tissue sparing using volumetric-modulated arc therapy (VMAT) or intensity-modulated radiation therapy (IMRT) for early-stage larynx cancer. Seven treatment plans were retrospectively created on 2 commercial treatment planning systems for 11 consecutive patients with T1-2N0 larynx cancer. Conventional plans consisted of opposed-wedged fields.

Thoracic target volume delineation using various maximum-intensity projection computed tomography image sets for radiotherapy treatment planning.

Purpose: Four-dimensional computed tomography (4D-CT) is commonly used to account for respiratory motion of target volumes in radiotherapy to the thorax. From the 4D-CT acquisition, a maximum-intensity projection (MIP) image set can be created and used to help define the tumor motion envelope or the internal gross tumor volume (iGTV). The purpose of this study was to quantify the differences in automatically contoured target volumes for usage in the delivery of stereotactic body radiation therapy using MIP data sets generated from one of the four methods: (1) 4D-CT phase-binned (PB) based on retrospective phase calculations, (2) 4D-CT phase-corrected phase-binned (PC-PB) based on motion extrema, (3) 4D-CT amplitude-binned (AB), and (4) cine CT built from all available images.

Target definition of moving lung tumors in positron emission tomography: correlation of optimal activity concentration thresholds with object size, motion extent, and source-to-background ratio.

Purpose: Hardware integration of fluorodeoxyglucose positron emission tomography (PET) with computed tomography (CT) in combined PET/CT scanners has provided radiation oncologists and physicists with new possibilities for 3-D treatment simulation. The use of PET/CT simulation for target delineation of lung cancer is becoming popular and many studies concerning automatic segmentation of PET images have been performed. Several of these studies consider size and source-to-background (SBR) in their segmentation methods but neglect respiratory motion.

Average CT in PET studies of colorectal cancer patients with metastasis in the liver and esophageal cancer patients.

Average CT (ACT) and PET have a similar temporal resolution and it has been shown to improve registration of the CT and PET data for PET/CT imaging of the thorax. The purpose of this study was to quantify the effect of ACT attenuation correction on PET for gross tumor volume (GTV) delineation with standardized uptake value (SUV) for liver and esophageal lesions. Our study included 48 colorectal cancer patients with metastasis in the liver and 52 esophageal cancer patients.

Variability of gross tumor volume delineation in head-and-neck cancer using PET/CT fusion, Part II: the impact of a contouring protocol.

The purpose of this study was to assess the efficacy of a gross tumor volume (GTV) contouring protocol on interobserver variability between 4 physicians in positron emission therapy/computed tomography (PET/CT) treatment planning of head-and-neck cancer. A GTV contouring protocol for PET/CT treatment planning was developed utilizing 4 stages: Preliminary contouring on CT alone, determination of appropriate PET windowing, accurate image registration, and modification of CT contouring with correctly formatted PET/CT display and rules for modality disagreement. Two neuroradiologists and 2 radiation oncologists (designated as A, B, C, and D, respectively) were given a tutorial of PET/CT coregistered imaging individualized to their skill level, which included a step-by-step explanation of the protocol with clinical examples.

Dose calculation with respiration-averaged CT processed from cine CT without a respiratory surrogate.

Dose calculation for thoracic radiotherapy is commonly performed on a free-breathing helical CT despite artifacts caused by respiratory motion. Four-dimensional computed tomography (4D-CT) is one method to incorporate motion information into the treatment planning process. Some centers now use the respiration-averaged CT (RACT), the pixel-by-pixel average of the ten phases of 4D-CT, for dose calculation.