Prospective evaluation of patient-reported anxiety and experiences with adaptive radiation therapy on an MR-linac.

Purpose: An integrated magnetic resonance scanner and linear accelerator (MR-linac) was implemented with daily online adaptive radiation therapy (ART). This study evaluated patient-reported experiences with their overall hospital care as well as treatment in the MR-linac environment.

Methods: Patients pre-screened for MR eligibility and claustrophobia were referred to simulation on a 1.

Framework Development: Standardizing Definition of Advanced Practice Radiation Therapy Activities for Clinical Workload Quantification.

Purpose: Advanced practice (AP) in radiation therapy (RT) is being implemented around the globe. In an effort to advance the understanding of the similarities and differences in APRT roles in Ontario, Canada, a community of practice (CoP) sought ways to provide quantitative data on the nature of APRT clinical activities and the frequency with which these activities were being executed.

Methods: In 2017, a consensus building project involving 20 APRTs and 14 radiation therapy (RT) department managers in Ontario was completed to establish a mechanism to quantify APRTs' clinical impact.

Clinical and dosimetric outcomes of image-guided, dose-painted radiotherapy in muscle invasive bladder cancer.

Purpose/objective: Definitive radiotherapy (RT) is an alternative to radical cystectomy for select patients with muscle invasive bladder cancer (MIBC); however, there is limited data on dose-painted RT approaches. We report the clinical and dosimetric outcomes of a cohort of MIBC patients treated with dose-painted RT.

Material/methods: This was a single institution retrospective study of cT2-4N0M0 MIBC patients treated with external beam radiotherapy (EBRT) to the bladder, and sequential or concomitant boost to the tumor bed.

Practice-based training strategy for therapist-driven prostate MR-Linac adaptive radiotherapy.

Purpose: To develop a practice-based training strategy to transition from radiation oncologist to therapist-driven prostate MR-Linac adaptive radiotherapy.

Methods And Materials: In phase 1, 7 therapists independently contoured the prostate and organs-at-risk on T2-weighted MR images from 11 previously treated MR-Linac prostate patients. Contours were evaluated quantitatively (i.

The dosimetric underpinning of bladder filling criteria for prostate image-guided volumetric modulated arc therapy.

Objectives: Repeated CT simulation imaging is common at our institution due to failure to achieve acceptable bladder filling in patients undergoing prostate radiotherapy. There is operational value in re-assessing the validity of the bladder filling assessment criteria by comparing the quality of two plans optimized based on either an "Accepted" or "Rejected" bladder status.

Methods: Twenty prostate patients with repeated CT simulation imaging were included.

Impact of intrafraction changes in delivered dose of the day for prostate cancer patients treated with stereotactic body radiotherapy via MR-Linac.

Purpose: The purpose of this study is to evaluate the impact of intrafraction pelvic motion by comparing the adapted plan dose (APD) and the computed delivered dose of the day (DDOTD) for patients with prostate cancer (PCa) treated with SBRT on the MR-Linac.

Methods: Twenty patients with PCa treated with MR-guided adaptive SBRT were included. A 9-field IMRT distribution was adapted based on the anatomy of the day to deliver a total prescription dose of 3000 cGy in 5 fractions to the prostate plus a 5 mm isotropic margin.

Case Report: MR-Guided Adaptive Radiotherapy, Some Room to Maneuver.

Background: A magnetic resonance linear accelerator (MR-Linac) provides superior soft tissue contrast to evaluate inter- and intra-fraction motion and facilitate online adaptive radiation therapy (ART). We present here an unusual case of locally advanced castrate-resistant prostate cancer treated with high-dose palliative ultra-hypofractionated radiation therapy on the MR-Linac with significant inter-fraction tumor regression.

Case Presentation: The patient was a 65-year-old man diagnosed with metastatic prostate cancer to bone and pelvic lymph nodes 7 years prior.

Dosimetric comparison of MR-guided adaptive IMRT versus 3DOF-VMAT for prostate stereotactic radiotherapy.

Introduction: To compare the dosimetry of prostate stereotactic radiotherapy (SBRT) delivered by adaptive intensity modulated radiotherapy (A-IMRT) and 3 degree of freedom volumetric modulated arc therapy (3DOF-VMAT).

Methods & Materials: Twenty-five prostate patients treated with High Dose Rate (HDR) brachytherapy followed by SBRT were included (fifteen with hydrogel spacer in place for treatment). Interfraction changes in the volume of prostate, rectum and bladder were measured.

Clinical integration of machine learning for curative-intent radiation treatment of patients with prostate cancer.

Machine learning (ML) holds great promise for impacting healthcare delivery; however, to date most methods are tested in 'simulated' environments that cannot recapitulate factors influencing real-world clinical practice. We prospectively deployed and evaluated a random forest algorithm for therapeutic curative-intent radiation therapy (RT) treatment planning for prostate cancer in a blinded, head-to-head study with full integration into the clinical workflow. ML- and human-generated RT treatment plans were directly compared in a retrospective simulation with retesting (n = 50) and a prospective clinical deployment (n = 50) phase.

Prostate or bone? Comparing the efficacy of image guidance surrogates for pelvis and prostate radiotherapy using accumulated delivered dose.

Introduction: This study assessed the impact of dosimetry to both the target and normal tissue when either bony anatomy (BA) or prostate (PRO) was used as surrogates for image guidance for pelvis and prostate radiotherapy using a dose accumulation process.

Methods: Thirty patients who were prescribed 50-54Gy to the pelvic lymph nodes (PLN) and 78Gy to the prostate/seminal vesicles were included. Daily acquired CBCTs were rigidly registered to the CT using BA and PRO to simulate two different treatment positions.

Impact of high dose volumetric CT on PTV margin reduction in VMAT prostate radiotherapy.

The aim of the study is to determine PTV margin for inter-observer variability in the volumetric modulated arc therapy (VMAT) prostate radiotherapy with high-dose volumetric CT (HDVCT) and conventional helical CT (CCT) for planning. Secondly to investigate the impact of geometric (PTV expansion) and dosimetric (conformity) imperfection of planning process on the PTV margin analysis. Prostate gland of ten patients were scanned with CCT and HDVCT techniques consecutively on a 320 slice volumetric CT scanner with wide field detector of 16 cm.

Efficient and Effective Personalization of PTV Margins During Radiation Therapy for Bladder Cancer.

Introduction: The magnitude of bladder filling variation during bladder cancer radiation therapy varies considerably between patients. Population-based approaches for planning target volume (PTV) margin calculation may be suboptimal for this disease site, and a strategy for personalizing PTV margins for each patient may be particularly beneficial. The purpose of this study was to identify the optimal number and sampling pattern of cone beam CT image data sets that are required when generating personalized PTV margins for whole bladder (WB) and partial bladder (PB) radiation therapy.

Quantification of interobserver variability in image registration using cone beam CT for partial bladder radiotherapy-a comparison between lipiodol and bladder wall surface.

Objective:: The use of lipiodol or bladder wall surface (BWS) for image guidance has improved the treatment quality for partial bladder irradiation. Currently, this procedure is manually performed by different users. This study assessed the interobserver variability of using image guidance for partial bladder irradiation.

Evaluation of resource burden for bladder adaptive strategies: A timing study.

Introduction: Interfraction bladder motion is substantial and therefore many different adaptive radiotherapy approaches have been developed to accommodate that motion. Previous studies comparing the efficacy of those adaptive strategies have demonstrated that reoptimization (ReOpt) was dosimetrically superior when compared to Plan of the Day (POD) and Patient-specific PTV (PS-PTV). However, the feasibility of clinical implementation is dependent upon assessment of the resource burden.

Comparison of 3 image-guided adaptive strategies for bladder locoregional radiotherapy.

The objective of this study was to compare the dosimetric differences of a population-based planning target volume (PTV) approach and 3 proposed adaptive strategies: plan of the day (POD), patient-specific PTV (PS-PTV), and daily reoptimization (ReOpt). Bladder patients (n = 10) were planned and treated to 46 Gy in 23 fractions with a full bladder in supine position by the standard strategy using a population-based PTV. For each patient, the adaptive strategy was executed retrospectively as follows: (1) POD-multiple distributions of various PTV sizes were generated, and the appropriate distribution based on the bladder of the day was selected for each fraction; (2) PS-PTV-population-based PTV was used for the first 5 fractions and a new PTV derived using information from these fractions was used to deliver the remaining 18 fractions; and (3) ReOpt-distribution was reoptimized for each fraction based on the bladder of the day.

Evaluation of high dose volumetric CT to reduce inter-observer delineation variability and PTV margins for prostate cancer radiotherapy.

Purpose: The aim was to determine whether the enhanced soft tissue contrast provided by high-dose volumetric CT (HDVCT) can reduce inter-observer variability in delineating prostate compared to helical conventional CT (CCT) scans and 3T MRI scans for patients undergoing radical prostate cancer radiotherapy. Secondly, to quantify the potential PTV reduction with decreased inter-observer variability.

Materials And Methods: A 320 slice volumetric CT scanner was used.

Adaptive Radiotherapy for Bladder Cancer-A Systematic Review.

Introduction: Radiotherapy has been offered as a multimodality treatment for bladder cancer patients. Due to the significant variation of bladder volume observed throughout the course of treatment, large margins in the range of 20-30 mm have been used, unnecessarily irradiating a large volume of normal tissue. With the capability of visualizing soft tissue in cone beam computed tomography, there is opportunity to modify or to adapt the plan based on the variation observed during the course of treatment for quality improvement.

The effect of bowel preparation regime on interfraction rectal filling variation during image guided radiotherapy for prostate cancer.

Background: This study aimed to investigate the tolerability and impact of milk of magnesia (MoM) on interfraction rectal filling during prostate cancer radiotherapy.

Methods: Two groups were retrospectively identified, each consisting of 40 patients with prostate cancer treated with radiotherapy to prostate+/-seminal vesicles, with daily image-guidance in 78Gy/39fractions/8 weeks. The first-group followed anti-flatulence diet with MoM started 3-days prior to planning-CT and continued during radiotherapy, while the second-group followed the same anti-flatulence diet only.

Planned versus 'delivered' bladder dose reconstructed using solid and hollow organ models during prostate cancer IMRT.

Background And Purpose: All studies to date have evaluated the dosimetric effect of bladder deformation using an organ model that includes the dose to the urine. This research reconstructed bladder dose using both hollow and solid organ models, to determine if dose/volume differences exist.

Materials And Methods: 35 prostate IMRT patients were selected, who had received 78Gy in 39 fractions and full bladder instructions.

Cone Beam Computed Tomography: The Challenges and Strategies in Its Application for Dose Accumulation.

Online image guidance using cone beam computed tomography (CBCT) has greatly improved the geometric precision of radiotherapy. Changes in anatomy are common during a course of fractionated treatment, resulting in dose deviation from the planned distribution. There is increased interest in performing dose accumulation to compute the actual delivered dose and to adapt the treatment when necessary.

Automated Delineation of the Normal Urinary Bladder on Planning CT and Cone Beam CT.

Purpose: To quantify the volumetric effect of delineation variability when using manual versus semiautomated tools to contour the normal bladder on planning computed tomography (CT) and cone beam CT.

Methods: Following research ethics board approval, 10 prostate cancer patients were selected. For each patient, one pretreatment cone beam CT (CBCT) was randomly selected from the first treatment week and registered to the planning CT (planCT).

Impact of image registration surrogates on the planning target volume geometry for bladder radiation therapy.

Purpose: The use of Lipiodol and cone beam computed tomography (CT) has facilitated the generation of patient-specific planning target volumes (PTV) to reduce irradiation of normal tissue. However, injecting Lipiodol to demarcate the target volume is an invasive procedure. Center of bladder (COB) and bladder wall surface (BWS) encompassed by the clinical target volume (CTV) are proposed to be the alternative noninvasive surrogates.

Stereotactic Body Radiation Therapy for Liver Cancer: A Review of the Technology.

Stereotactic body radiation therapy has been adopted in the treatment of liver cancer because of its highly conformal dose distribution when compared with other conventional approaches, and many studies have been published to report the positive clinical outcome associated with this technique. To achieve the precision needed to maintain or to improve the therapeutic ratio, various strategies are applied in different components in the stereotactic body radiation therapy process. Immobilization devices are used in minimizing geometric uncertainty induced by treatment positioning and internal organ motion.

Phase 2 trial of guideline-based postoperative image guided intensity modulated radiation therapy for prostate cancer: Toxicity, biochemical, and patient-reported health-related quality-of-life outcomes.

Purpose: The purpose of this study was to characterize treatment-related toxicities, health-related quality of life (HRQOL), and biochemical outcomes in patients treated with postoperative image guided intensity modulated radiation therapy (IMRT) for prostate cancer using a consensus guideline for defining the clinical target volume.

Methods And Materials: Between August 2007 and October 2008, patients considered for radiation therapy (RT) after prostatectomy were enrolled. The clinical target volume (prostate bed) was delineated according to published consensus guidelines, and patients were prescribed a dose of 66 Gy in 33 fractions.

Deriving patient-specific planning target volume for partial bladder image guided radiation therapy.

Purpose: Image guided radiation therapy (IGRT) using bony anatomy for bladder cancer requires the use of large population-based planning target volume (PTV) margins to compensate for geometric uncertainties. This may result in a large volume of normal tissue being irradiated unnecessarily. Identification of the clinical target volume (CTV) is also a challenge during target delineation and treatment position verification.