Feasibility of patient-specific quality assurance (PSQA) for real-time robotic stereotactic body radiotherapy (SBRT) based on tumor motion traces.

PURPOSE: To design a patient specific quality assurance (PSQA) process for the CyberKnife Synchrony system and quantify its dosimetric accuracy using a motion platform driven by patient tumor traces with rotation. METHODS: The CyberKnife Synchrony system was evaluated using a motion platform (MODUSQA) and a SRS MapCHECK phantom. The platform was programed to move in the superior-inferior (SI) direction based on tumor traces. The detector array housed by the StereoPhan was placed on the platform. Extra rotational angles in pitch (head down, 4.0° ± 0.15° or 1.2° ± 0.1°) were added to the moving phantom to examine robot capability of angle correction during delivery. A total of 15 Synchrony patients were performed SBRT PSQA on the moving phantom. All the results were benchmarked by the PSQA results based on static phantom. RESULTS: For smaller pitch angles, the mean gamma passing rates were 99.75% ± 0.87%, 98.63% ± 2.05%, and 93.11% ± 5.52%, for 3%/1 mm, 2%/1 mm, and 1%/1 mm, respectively. Large discrepancy in the passing rates was observed for different pitch angles due to limited angle correction by the robot. For larger pitch angles, the corresponding mean passing rates were dropped to 93.00% ± 10.91%, 88.05% ± 14.93%, and 80.38% ± 17.40%. When comparing with the static phantom, no significant statistic difference was observed for smaller pitch angles (p = 0.1 for 3%/1 mm), whereas a larger statistic difference was observed for larger pitch angles (p < 0.02 for all criteria). All the gamma passing rates were improved, if applying shift and rotation correction. CONCLUSIONS: The significance of this work is that it is the first study to benchmark PSQA for the CyberKnife Synchrony system using realistically moving phantoms with rotation. With reasonable delivery time, we found it may be feasible to perform PSQA for Synchrony patients with a realistic breathing pattern.

Implementing and evaluating a high-resolution diode array for patient-specific quality assurance of robotic brain stereotactic radiosurgery/radiotherapy.

The purpose of the study was to introduce and evaluate a high-resolution diode array for patient-specific quality assurance (PSQA) of CyberKnife brain stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT). Thirty-three intracranial plans were retrospectively delivered on the SRS MapCHECK using fixed cone, Iris, and multileaf collimator (MLC). The plans were selected to cover a range of sites from large tumor bed, single/multiple small brain metastases (METs) to trigeminal neuralgia. Fiducial tracking using the four fiducials embedded around the detector plane was used as image guidance. Results were analyzed before and after registration based on absolute dose gamma criterion of 1 mm distance-to-agreement and 0.5%-3% dose-difference. Overall, the gamma passing rates (1 mm and 3% criterion) before registration for all the patients were above 90% for all three treatment modalities (96.8 ± 3.5%, the lowest passing rate of 90.4%), and were improved after registration (99.3 ± 1.5%). When tighter criteria (1 mm and 2%) were applied, the gamma passing rates after registration for all the cases dropped to 97.3 ± 3.2%. For trigeminal neuralgia cases, we applied 1 mm and 0.5% criterion and the passing rates dropped from 100 ± 0.0% to 98.5 ± 2.0%. The mean delivery time was 33.4 ± 11.7 min, 24.0 ± 4.9 min, and 17.1 ± 2.6 min for the fixed cone, Iris, and MLC, respectively. With superior gamma passing rates and reasonable quality assurance (QA) time, we believe the SRS MapCHECK could be a good option for routine PSQA for CyberKnife SRS/SRT.

Development and validation of the Trans- and Nonbinary-Affirming Parental Practices (TAPP) measure.

Parental support is instrumental in protecting the mental health of trans and nonbinary youth (TNB). Yet minimal measures exist that measure parental support, and current measures typically measure parental attitudes or general perceptions of supportiveness rather than measuring specific TNB-affirming behaviors. This study aimed to fill this gap by developing and validating the Trans- and Nonbinary-Affirming Parental Practices scale. The scale items were developed based on existing psychological literature on TNB-affirming parenting behaviors as well as adapting existing measures. The sample consisted of 570 parents or caregivers of TNB youth ages 5-27 (M = 15). The vast majority of participants were White (90%) and cisgender women (92%). The sample was randomly split to conduct both exploratory factor analysis and confirmatory factor analysis. Factor analysis found good fit for a four-factor structure with 14 items. Each subscale represented a type of TNB-affirming parental behavior: communicating support, affirming language, advocating for their TNB child, and seeking affirming resources. The measure demonstrated invariance with both heterosexual participants and participants with minoritized sexual identities and demonstrated convergent and discriminant validity. The Trans- and Nonbinary-Affirming Parental Practices measure can be useful in intervention research aimed at increasing TNB-affirming behaviors among parents and caregivers of TNB youth. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Development and Validation of the Sexual Minority and Religious Identity Integration (SMRII) Scale.

Despite the psychosocial strain of homonegative religious attitudes, many people with minoritized sexual identities also hold religious identities and benefit from integrating their sexual minority and religious identities. However, for research and clinical practice to advance, a reliable and valid measure of sexual and religious identity integration is needed. The present study reports on the development and validation of the Sexual Minority and Religious Identity Integration (SMRII) Scale. Participants were comprised of two subsamples for whom sexual and religious identity is particularly salient (Latter-day Saints and Muslims) as well as a third subsample of the general sexual minority population-totaling 1,424 individuals (39% POC, 62% cisman, 27% ciswoman, 11% trans/non-binary/genderqueer). Exploratory and confirmatory factor analyses indicated that the 5-item scale measures a single unidimensional construct. This scale demonstrated good internal consistency in the total sample (α = .80) as well as metric and scalar invariance along relevant demographics. The SMRII also evidenced strong convergent and discriminant validity, significantly correlating with other measures of religious and sexual minority identity typically between r = .2 and r = .5. Taken together, initial findings indicate that the SMRII is a psychometrically sound measure that is brief enough to be utilized in research and clinical settings.Public Significance Statement: This article introduces the Sexual Minority and Religious Identity Integration Scale (SMRII) as a reliable and valid assessment of the degree to which individuals integrate their sexual minority and religious identities. This five-item measure is brief enough to be utilized in both research and clinical settings.

Is there a role for arcing techniques in proton therapy?

Proton arc therapy (PAT) has been proposed as a possible evolution for proton therapy. This commentary uses dosimetric and cancer risk evaluations from earlier studies to compare PAT with intensity modulated proton therapy. It is concluded that, although PAT may not produce better physical dose distributions than intensity modulated proton therapy, the radiobiological considerations associated with particular PAT techniques could offer the possibility of an increased therapeutic index.

Radiobiological effectiveness difference of proton arc beams versus conventional proton and photon beams.

This paper aims to demonstrate the difference in biological effectiveness of proton monoenergetic arc therapy (PMAT) compared to intensity modulated proton therapy (IMPT) and conventional 6 MV photon therapy, and to quantify this difference when exposing cells of different radiosensitivity to the same experimental conditions for each modality. V79, H1299 and H460 cells were cultured in petri dishes placed in the central axis of a cylindrical and homogeneous solid water phantom of 20 cm in diameter. For the PMAT plan, cells were exposed to 13 mono-energetic proton beams separated every 15° over a 180° arc, designed to deliver a uniform dose of higher LET to the petri dishes. For the IMPT plans, 3 fields were used, where each field was modulated to cover the full target. Cells were also exposed to 6 MV photon beams in petri dishes to characterize their radiosensitivity. The relative biological effectiveness of the PMAT plans compared with those of IMPT was measured using clonogenic assays. Similarly, in order to study the quantity and quality of the DNA damage induced by the PMAT plans compared to that of IMPT and photons, γ-H2AX assays were conducted to study the relative amount of DNA damage induced by each modality, and their repair rate over time. The clonogenic assay revealed similar survival levels to the same dose delivered with IMPT or x-rays. However, a systematic average of up to a 43% increase in effectiveness in PMAT plans was observed when compared with IMPT. In addition, the repair kinetic assays proved that PMAT induces larger and more complex DNA damage (evidenced by a slower repair rate and a larger proportion of unrepaired DNA damage) than IMPT. The repair kinetics of IMPT and 6 MV photon therapy were similar. Mono-energetic arc beams offer the possibility of taking advantage of the enhanced LET of proton beams to increase TCP. This study presents initial results based on exposing cells with different radiosensitivity to other modalities under the same experimental conditions, but more extensive clonogenic and in-vivo studies will be required to confirm the validity of these results.

Reproducibility of differential gene detection across multiple microarray studies.

Although expression profiling of various diseases to identify interesting genes is a well-established methodology, it still faces many challenges. Labs often have difficulty reproducing results on different microarray platforms. Microarray manufacturers use different clones to represent similar genes on various platforms. Consequently, researchers struggle to integrate data published in literature and databases. Even results from identical microarray platforms may not correlate due to technical variability between labs. We seek some degree of congruity between the same microarray platforms implemented at multiple test sites. We analyze two prostate cancer datasets from commercially synthesized oligonucleotide arrays (Affymetrix HG-U95v2). Our analysis focuses on determining reproducibility in identifying differentially expressed genes using fold change and t-tests. We use p-values to compare specificity and sensitivity of the methods applied to each dataset. Findings indicate that, even though both datasets use the same microarray platform, differences in experimental design and test conditions result in variations when detecting differentially expressed genes.

Improved bolstering error estimation for gene ranking.

Many methods have been proposed to identify differentially expressed genes in diseased tissues. The performance of the method is closely related to the evaluation metric. We examine several error estimation algorithms (i.e., cross validation, bootstrap, resubstitution, and resubstitution with bolstering) for three classifiers (i.e., support vector machine, Fisher's discriminant, and signed distance function). To control the classifier's data-overfitting problem, usually caused by small sample size for many real datasets, we generate synthetic datasets based on real data. This way, we can monitor sample size impact when evaluating the metrics. We find that resubstitution with bolstering has the best result, especially with respect to computational efficiency. However, classical bolstering tends to bias in high dimensions. Thus, we further investigate ways to reduce bolstering estimation bias without increasing computational intensity. Results of our investigation indicate that the estimator tends to become unbiased as the sample size increases. We also find that modified bolstering is the best among all metrics in terms of estimation accuracy and computational efficiency.