Order From Chaos: The Benefits of Standardized Nomenclature in Radiation Oncology

Although standardization has been shown to improve patient safety and improve the efficiency of workflows, implementation of standards can take considerable effort and requires the engagement of all clinical stakeholders. Engaging team members includes increasing awareness of the proposed benefit of the standard, a clear implementation plan, monitoring for improvements, and open communication to support successful implementation. The benefits of standardization often focus on large institutions to improve research endeavors, yet all clinics can benefit from standardization to increase quality and implement more efficient or automated workflow. The benefits of nomenclature standardization for all team members and institution sizes, including success stories, are discussed with practical implementation guides to facilitate the adoption of standardized nomenclature in radiation oncology.

Deep learning-based target decomposition for markerless lung tumor tracking in radiotherapy

BACKGROUND

In radiotherapy, real-time tumor tracking can verify tumor position during beam delivery, guide the radiation beam to target the tumor, and reduce the chance of a geometric miss. Markerless kV x-ray image-based tumor tracking is challenging due to the low tumor visibility caused by tumor-obscuring structures. Developing a new method to enhance tumor visibility for real-time tumor tracking is essential.

PURPOSE

To introduce a novel method for markerless kV image-based tracking of lung tumors via deep learning-based target decomposition.

METHODS

We utilized a conditional Generative Adversarial Network (cGAN), known as Pix2Pix, to build a patient-specific model and generate the synthetic decomposed target image (sDTI) to enhance tumor visibility on the real-time kV projection images acquired by the onboard kV imager equipped on modern linear accelerators. We used 4DCT simulation images to generate the digitally reconstructed radiograph (DRR) and DTI image pairs for model training. We augmented the training dataset by randomly shifting the 4DCT in the superior-inferior, anterior-posterior, and left-right directions during the DRR and DTI generation process. We performed real-time 2D tumor tracking via template matching between the DTI generated from the CT simulation and the sDTI generated from the real-time kV projection images. We validated the proposed method using nine patients' datasets with implanted beacons near the tumor.

RESULTS

The sDTI can effectively improve the image contrast around the lung tumors on the kV projection images for the nine patients. With the beacon motion as ground truth, the tracking errors were on average 0.8 ± 0.7 mm in the superior-inferior (SI) direction and 0.9 ± 0.8 mm in the in-plane left-right (IPLR) direction. The percentage of successful tracking, defined as a tracking error less than 2 mm in the SI direction, is 92.2% on the 4312 tested images. The patient-specific model took approximately 12 h to train. During testing, it took approximately 35 ms to generate one sDTI, and 13 ms to perform the tumor tracking using template matching.

CONCLUSIONS

Our method offers the potential solution for nearly real-time markerless lung tumor tracking. It achieved a high level of accuracy and an impressive tracking rate. Further development of 3D lung tumor tracking is warranted.

Are We Missing Acute Toxicities Associated With Hypofractionated Breast Irradiation? A Report From a Large Multicenter Cohort Study

PURPOSE

The efficacy and long-term safety of hypofractionated whole breast irradiation (HF-WBI) have been established through multiple randomized trials, yet data about acute toxicities remain more limited. Since 2013, our group has prospectively collected acute toxicity data from weekly treatment evaluations and additional assessment after completion. In 2016, we intentionally shifted the posttreatment assessment follow-up visit from 1 month to 2 weeks to evaluate for missed acute toxicity occurring in that immediate posttreatment window. Here, we report whether 2-week follow-up has resulted in increased detection of acute toxicities compared with 4-week follow-up.

METHODS AND MATERIALS

We prospectively compared acute toxicity for patients treated with HF-WBI between January 1, 2013, and August 31, 2015 (4 week follow-up cohort) to patients treated between January 1, 2016, and August 31, 2018 (2 week follow-up cohort). Analyses included a multivariable model that adjusted for other factors known to correlate with toxicity. We prospectively defined acute toxicity as maximum breast pain (moderate or severe rating) and/or occurrence of moist desquamation reported 7 days before the completion of radiation therapy (RT) until 42 days after completion.

RESULTS

A total of 2689 patients who received postlumpectomy radiation and boost were analyzed; 1862 patients in the 2-week follow-up cohort and 827 in the 4-week follow-up cohort. All acute toxicity measures assessed were statistically similar between follow-up cohorts when compared in an unadjusted fashion. Overall acute composite toxicity was 26.4% and 27.7% for patients in the 4-week follow-up and 2-week follow-up cohorts, respectively. Overall acute composite toxicity remained similar between follow-up cohorts in a multivariable, adjusted model and was significantly related to patient's age, body mass index, smoking status, and treatment technique (intensity-modulated RT vs 3-dimensional conformal radiation therapy) but not follow-up cohort.

CONCLUSIONS

An earlier posttreatment follow-up for HF-WBI patients did not reveal a significant increased incidence of acute toxicities at 2 weeks compared with 4 weeks. This study provides physicians and patients with additional data on the safety and tolerability of HF-WBI for early stage breast cancer.

Toward quantitative intrafractional monitoring in paraspinal SBRT using a proprietary software application: clinical implementation and patient results

Objective.We report on paraspinal motion and the clinical implementation of our proprietary software that leverages Varian's intrafraction motion review (IMR) capability for quantitative tracking of the spine during paraspinal SBRT. The work is based on our prior development and analysis on phantoms.Approach.To address complexities in patient anatomy, digitally reconstructed radiographs (DRR's) that highlight only the spine or hardware were constructed as tracking reference. Moreover, a high-pass filter and first-pass coarse search were implemented to enhance registration accuracy and stability. For evaluation, 84 paraspinal SBRT patients with sites spanning across the entire vertebral column were enrolled with prescriptions ranging from 24 to 40 Gy in one to five fractions. Treatments were planned and delivered with 9 IMRT beams roughly equally distributed posteriorly. IMR was triggered every 200 or 500 MU for each beam. During treatment, the software grabbed the IMR image, registered it with the corresponding DRR, and displayed the motion result in near real-time on auto-pilot mode. Four independent experts completed offline manual registrations as ground truth for tracking accuracy evaluation.Main results.Our software detected ≥1.5 mm and ≥2 mm motions among 17.1% and 6.6% of 1371 patient images, respectively, in either lateral or longitudinal direction. In the validation set of 637 patient images, 91.9% of the tracking errors compared to manual registration fell within ±0.5 mm in either direction. Given a motion threshold of 2 mm, the software accomplished a 98.7% specificity and a 93.9% sensitivity in deciding whether to interrupt treatment for patient re-setup.Significance.Significant intrafractional motion exists in certain paraspinal SBRT patients, supporting the need for quantitative motion monitoring during treatment. Our improved software achieves high motion tracking accuracy clinically and provides reliable guidance for treatment intervention. It offers a practical solution to ensure accurate delivery of paraspinal SBRT on a conventional Linac platform.

Enhancing the target visibility with synthetic target specific digitally reconstructed radiograph for intrafraction motion monitoring: A proof-of-concept study

BACKGROUND

Intrafraction motion monitoring in External Beam Radiation Therapy (EBRT) is usually accomplished by establishing a correlation between the tumor and the surrogates such as an external infrared reflector, implanted fiducial markers, or patient skin surface. These techniques either have unstable surrogate-tumor correlation or are invasive. Markerless real-time onboard imaging is a noninvasive alternative that directly images the target motion. However, the low target visibility due to overlapping tissues along the X-ray projection path makes tumor tracking challenging.

PURPOSE

To enhance the target visibility in projection images, a patient-specific model was trained to synthesize the Target Specific Digitally Reconstructed Radiograph (TS-DRR).

METHODS

Patient-specific models were built using a conditional Generative Adversarial Network (cGAN) to map the onboard projection images to TS-DRR. The standard Pix2Pix network was adopted as our cGAN model. We synthesized the TS-DRR based on the onboard projection images using phantom and patient studies for spine tumors and lung tumors. Using previously acquired CT images, we generated DRR and its corresponding TS-DRR to train the network. For data augmentation, random translations were applied to the CT volume when generating the training images. For the spine, separate models were trained for an anthropomorphic phantom and a patient treated with paraspinal stereotactic body radiation therapy (SBRT). For lung, separate models were trained for a phantom with a spherical tumor insert and a patient treated with free-breathing SBRT. The models were tested using Intrafraction Review Images (IMR) for the spine and CBCT projection images for the lung. The performance of the models was validated using phantom studies with known couch shifts for the spine and known tumor deformation for the lung.

RESULTS

Both the patient and phantom studies showed that the proposed method can effectively enhance the target visibility of the projection images by mapping them into synthetic TS-DRR (sTS-DRR). For the spine phantom with known shifts of 1 mm, 2 mm, 3 mm, and 4 mm, the absolute mean errors for tumor tracking were 0.11 ± 0.05 mm in the x direction and 0.25 ± 0.08 mm in the y direction. For the lung phantom with known tumor motion of 1.8 mm, 5.8 mm, and 9 mm superiorly, the absolute mean errors for the registration between the sTS-DRR and ground truth are 0.1 ± 0.3 mm in both the x and y directions. Compared to the projection images, the sTS-DRR has increased the image correlation with the ground truth by around 83% and increased the structural similarity index measure with the ground truth by around 75% for the lung phantom.

CONCLUSIONS

The sTS-DRR can greatly enhance the target visibility in the onboard projection images for both the spine and lung tumors. The proposed method could be used to improve the markerless tumor tracking accuracy for EBRT.

Implementation of a knowledge-based decision support system for treatment plan auditing through automation

BACKGROUND

Independent auditing is a necessary component of a comprehensive quality assurance (QA) program and can also be utilized for continuous quality improvement (QI) in various radiotherapy processes. Two senior physicists at our institution have been performing a time intensive manual audit of cross-campus treatment plans annually, with the aim of further standardizing our planning procedures, updating policies and guidelines, and providing training opportunities of all staff members.

PURPOSE

A knowledge-based automated anomaly-detection algorithm to provide decision support and strengthen our manual retrospective plan auditing process was developed. This standardized and improved the efficiency of the assessment of our external beam radiotherapy (EBRT) treatment planning across all eight campuses of our institution.

METHODS

A total of 843 external beam radiotherapy plans for 721 lung patients from January 2020 to March 2021 were automatically acquired from our clinical treatment planning and management systems. From each plan, 44 parameters were automatically extracted and pre-processed. A knowledge-based anomaly detection algorithm, namely, "isolation forest" (iForest), was then applied to the plan dataset. An anomaly score was determined for each plan using recursive partitioning mechanism. Top 20 plans ranked with the highest anomaly scores for each treatment technique (2D/3D/IMRT/VMAT/SBRT) including auto-populated parameters were used to guide the manual auditing process and validated by two plan auditors.

RESULTS

The two auditors verified that 75.6% plans with the highest iForest anomaly scores have similar concerning qualities that may lead to actionable recommendations for our planning procedures and staff training materials. The time to audit a chart was approximately 20.8 min on average when done manually and 14.0 min when done with the iForest guidance. Approximately 6.8 min were saved per chart with the iForest method. For our typical internal audit review of 250 charts annually, the total time savings are approximately 30 hr per year.

CONCLUSION

iForest effectively detects anomalous plans and strengthens our cross-campus manual plan auditing procedure by adding decision support and further improve standardization. Due to the use of automation, this method was efficient and will be used to establish a standard plan auditing procedure, which could occur more frequently.

Failure Mode and Effects Analysis Prior to the Introduction of AI Generated GTVs for Brain Metastases in the Clinical Workflow

PURPOSE/OBJECTIVE(S)

AI autosegmentation of organs-at-risk (OARs) is common practice at many radiotherapy clinics. Despite the abundance of gross tumor volume (GTV) autosegmentation algorithms, adoption in clinical care has been slow due to the high risk associated with errors in GTV delineation. Here we present a failure mode and effects analysis (FMEA) to evaluate the risk associated with introducing AI derived GTVs in patients treated with stereotactic radiosurgery (SRS).

MATERIALS/METHODS

An AI GTV autosegmentation algorithm for brain metastases was developed in-house based on a V-Net 3D CNN. Registered CT and MR images and a contour of the brain are input into the software and all identified lesions are returned in a DICOM-RT structure set. Following algorithm evaluation, a workflow was developed to enable AI GTV autosegmentation to be introduced clinically for every SRS patient. The following steps were added to existing procedures: 1) workflow to send CT/MR and brain structure to external server, 2) autosegmentation run on the server, 3) AI GTV structures with a standard nomenclature added to existing OAR structure set, and 4) MD review, editing, and approval of AI GTVs. After successfully completing the physics evaluation testing of the new process, we formed a team of 10 faculty and staff including physicists, residents, physicians, and planners to perform the FMEA prior to clinical implementation. The team met to map the process, identify potential failure modes, and score their frequency of occurrence, severity, and detectability. A 3-point scale (1, 3, or 5) was used to simplify the scoring process. Occurrence was defined as rare, sometimes, or often; severity as low, medium, or high; and detectability as obvious, possible, or challenging. The risk probability numbers (RPNs) were calculated and the steps in the process with the highest RPNs were flagged for further discussion.

RESULTS

The FMEA team completed their process map and analysis primarily in 4 meetings. The process map began with acquisition of the patients CT simulation scan and ended with physician approval of final volumes for treatment planning. We identified 17 process steps and 72 possible failure modes, of which 26 were associated with the new workflow. Eighteen failure modes had an RPN greater than 30 (highest risk score in at least one category) and were flagged to assess mitigation strategies. Five were unique to the new AI GTV workflow and mitigation strategies will be designed prior to clinical use. Those involved risks related to inaccurate AI GTV contours, false positives, and an incomplete review stemming from over-reliance by team members on AI.

CONCLUSION

AI is increasingly being employed at every step of radiotherapy to automate and streamline processes. The FMEA analysis resulted in the identification of the riskiest parts of using AI GTV autosegmentation. This can be an effective tool in the development of checks to ensure that GTV autosegmentation methods can be safely introduced in support of patient care.

Under-Representation for Female Cancers in Commercial Auto-Segmentation Solutions and Open-Source Imaging Datasets

PURPOSE/OBJECTIVE(S)

Auto-segmentations methods to aid radiation therapy (RT) workflows have recently emerged with the increasing availability of commercial solutions for organs at risk (OARs) in addition to open-source imaging datasets that support training for new auto-segmentation algorithms. Here, we explored whether female and male cancer sites are equally represented among these solutions.

MATERIALS/METHODS

Inquiries were sent out to five major RT vendors regarding their currently available auto-segmentation solutions. Additionally, The Cancer Imaging Archive (TCIA) was screened for publicly available imaging datasets pertaining to female and male tumor sites.

RESULTS

The five commercial solutions provided a median of 103 (range: 60-120) OAR auto-segmentations of which the majority concerned the head and neck (45 (24-55)) and thorax (34 (27-43)) and were provided by all vendors (Table). Prostate as a site was also provided by all vendors and included 17 (9-20) auto-segmentations. A total of 23 publicly available TCIA imaging datasets involved the female anatomy (breast: 19; cervix: 2; ovarian: 1; uterus: 1) while 11 imaging datasets involved the male anatomy (prostate). No OARs segmentations were available for the 23 female-specific datasets while 27% of the 11 prostate datasets included segmented OARs. Three vendors and two TCIA datasets provided organs involved in the male sexual function apparatus (neurovascular bundle and penile bulb), whereas nipple or areola segmentations were not available among the commercial solutions for breast or among the TCIA breast datasets. None of the TCIA datasets or any of the five commercial solutions provided OARs for the female pelvis such as organs involved in reproduction (ovaries), sexual health (clitoris, vagina) or the cervix and uterus. Further, auto-segmentations provided for OARs trained exclusively on the male pelvis are likely inadequate for female cancers given the substantial anatomical differences between genders.

CONCLUSION

Commercial auto-segmentation solutions and open-source imaging datasets together include considerably more datasets, tumor sites and consequently more OAR auto-segmentations pertaining to male cancers compared to female cancers. Despite a 1.4 times higher incidence for female cancers (breast: 300,590; female pelvis: 114,810; male cancer: 299,540; Siegel RL et al CA Cancer J Clin 2023), auto-segmentation models are lacking, and this gender disparity is likely to lead to suboptimal care for female-specific cancers.

Patient specific prior cross attention for kV decomposition in paraspinal motion tracking

BACKGROUND

X-ray image quality is critical for accurate intrafraction motion tracking in radiation therapy.

PURPOSE

This study aims to develop a deep-learning algorithm to improve kV image contrast by decomposing the image into bony and soft tissue components. In particular, we designed a priori attention mechanism in the neural network framework for optimal decomposition. We show that a patient-specific prior cross-attention (PCAT) mechanism can boost the performance of kV image decomposition. We demonstrate its use in paraspinal SBRT motion tracking with online kV imaging.

METHODS

Online 2D kV projections were acquired during paraspinal SBRT for patient motion monitoring. The patient-specific prior images were generated by randomly shifting and rotating spine-only DRR created from the setup CBCT, simulating potential motions. The latent features of the prior images were incorporated into the PCAT using multi-head cross attention. The neural network aimed to learn to selectively amplify the transmission of the projection image features that correlate with features of the priori. The PCAT network structure consisted of (1) a dual-branch generator that separates the spine and soft tissue component of the kV projection image and (2) a dual-function discriminator (DFD) that provides the realness score of the predicted images. For supervision, we used a loss combining mean absolute error loss, discriminator loss, perceptual loss, total variation, and mean squared error loss for soft tissues. The proposed PCAT approach was benchmarked against previous work using the ResNet generative adversarial network (ResNetGAN) without prior information.

RESULTS

The trained PCAT had improved performance in effectively retaining and preserving the spine structure and texture information while suppressing the soft tissues from the kV projection images. The decomposed spine-only x-ray images had the submillimeter matching accuracy at all beam angles. The decomposed spine-only x-ray significantly reduced the maximum errors to 0.44 mm (<2 pixels) in comparison to 0.92 mm (∼4 pixels) of ResNetGAN. The PCAT decomposed spine images also had higher PSNR and SSIM (p-value < 0.001).

CONCLUSION

The PCAT selectively learned the important latent features by incorporating the patient-specific prior knowledge into the deep learning algorithm, significantly improving the robustness of the kV projection image decomposition, and leading to improved motion tracking accuracy in paraspinal SBRT.

Automated VMAT treatment planning using sequential convex programming: algorithm development and clinical implementation

OBJECTIVE

To develop and clinically implement a fully automated treatment planning system for volumetric modulated arc therapy (VMAT).&#xD;Approach: We solve two constrained optimization problems sequentially. The tumor coverage is maximized at the first step while respecting all maximum/mean dose clinical criteria. The second step further reduces the dose at the surrounding organs-at-risk (OARs) as much as possible. Our algorithm optimizes the machine parameters (leaf positions and monitor units) directly and the resulting mathematical non-convexity is handled using thesequential convex programmingby solving a series of convex approximation problems. We directly integrate two novel convex surrogate metrics to improve plan delivery efficiency and reduce plan complexity by promoting aperture shape regularity and neighboring aperture similarity. The entire workflow is automated using the Eclipse treatment planning system (TPS) application program interface (API) scripting and provided to users as a plug-in, requiring the users to solely provide the contours and their preferred arcs. Our program provides the optimal machine parameters and does not utilize the Eclipse optimization engine, however, it utilizes the Eclipse final dose calculation engine. We have tested our program on 60 patients of different disease sites and prescriptions for stereotactic body radiotherapy (SBRT) (paraspinal (24Gy x 1, 9Gy x 3), oligometastis (9Gy x 3), lung (18Gy x 3, 12Gy x 4)) and retrospectively compared the automated plans with the manual plans used for treatment. The program is currently deployed in our clinic and being used in our daily clinical routine to treat patients. &#xD;Main results: The automated plans found dosimetrically comparable or superior to the manual plans. For paraspinal (24Gy x 1), the automated plans especially improved tumor coverage (the average PTV95% from 96% to 98% and CTV100% from 95% to 97%) and homogeneity (the average PTV maximum dose from 120% to 116%). For other sites/prescriptions, the automated plans especially improved the duty cycle (23%-39.4%).&#xD;Significance: This work proposes a fully automated approach to the mathematically challenging VMAT problem. It also shows how the capabilities of the existing FDA-approved commercial TPS can be enhanced using an in-house developed optimization algorithm that completely replaces the TPS optimization engine. The code and pertained models along with a sample dataset will be released on our ECHO-VMAT GitHub (https://github.com/PortPy-Project/ECHO-VMAT).

Multi-Institutional Stereotactic Body Radiation Therapy Incident Learning: Evaluation of Safety Barriers Using a Human Factors Analysis and Classification System

OBJECTIVES

Stereotactic body radiation therapy (SBRT) can improve therapeutic ratios and patient convenience, but delivering higher doses per fraction increases the potential for patient harm. Incident learning systems (ILSs) are being increasingly adopted in radiation oncology to analyze reported events. This study used an ILS coupled with a Human Factor Analysis and Classification System (HFACS) and barriers management to investigate the origin and detection of SBRT events and to elucidate how safeguards can fail allowing errors to propagate through the treatment process.

METHODS

Reported SBRT events were reviewed using an in-house ILS at 4 institutions over 2014-2019. Each institution used a customized care path describing their SBRT processes, including designated safeguards to prevent error propagation. Incidents were assigned a severity score based on the American Association of Physicists in Medicine Task Group Report 275. An HFACS system analyzed failing safeguards.

RESULTS

One hundred sixty events were analyzed with 106 near misses (66.2%) and 54 incidents (33.8%). Fifty incidents were designated as low severity, with 4 considered medium severity. Incidents most often originated in the treatment planning stage (38.1%) and were caught during the pretreatment review and verification stage (37.5%) and treatment delivery stage (31.2%). An HFACS revealed that safeguard failures were attributed to human error (95.2%), routine violation (4.2%), and exceptional violation (0.5%) and driven by personnel factors 32.1% of the time, and operator condition also 32.1% of the time.

CONCLUSIONS

Improving communication and documentation, reducing time pressures, distractions, and high workload should guide proposed improvements to safeguards in radiation oncology.

Quality and Safety Considerations in Intensity Modulated Radiation Therapy: An ASTRO Safety White Paper Update

PURPOSE

This updated report on intensity modulated radiation therapy (IMRT) is part of a series of consensus-based white papers previously published by the American Society for Radiation Oncology (ASTRO) addressing patient safety. Since the first white papers were published, IMRT went from widespread use to now being the main delivery technique for many treatment sites. IMRT enables higher radiation doses to be delivered to more precise targets while minimizing the dose to uninvolved normal tissue. Due to the associated complexity, IMRT requires additional planning and safety checks before treatment begins and, therefore, quality and safety considerations for this technique remain important areas of focus.

METHODS AND MATERIALS

ASTRO convened an interdisciplinary task force to assess the original IMRT white paper and update content where appropriate. Recommendations were created using a consensus-building methodology, and task force members indicated their level of agreement based on a 5-point Likert scale, from "strongly agree" to "strongly disagree." A prespecified threshold of ≥75% of raters who select "strongly agree" or "agree" indicated consensus.

CONCLUSIONS

This IMRT white paper primarily focuses on quality and safety processes in planning and delivery. Building on the prior version, this consensus paper incorporates revised and new guidance documents and technology updates. IMRT requires an interdisciplinary team-based approach, staffed by appropriately trained individuals as well as significant personnel resources, specialized technology, and implementation time. A comprehensive quality assurance program must be developed, using established guidance, to ensure IMRT is performed in a safe and effective manner. Patient safety in the delivery of IMRT is everyone's responsibility, and professional organizations, regulators, vendors, and end-users must work together to ensure the highest levels of safety.

Gender-Based Discrimination and Sexual Harassment in Medical Physics

PURPOSE

Gender-based discrimination and sexual harassment have been well-studied in the fields of science, technology, engineering, math, and medicine. However, less is known about these topics and their effect within the profession of medical physics. We aimed to better understand and clarify the views and experiences of practicing medical physicists and medical physics residents regarding gender-based discrimination and sexual harassment.

METHODS AND MATERIALS

We conducted in-depth, semistructured, and confidential interviews with 32 practicing medical physicists and medical physics residents across the United States. The interviews were broad and covered the topics of discrimination, mentorship, and work/life integration. All participants were associated with a department with a residency program accredited by the Commission on Accreditation of Medical Physics Education Programs and had appointments with a clinical component.

RESULTS

Participants shared views about gender-based discrimination and sexual harassment that were polarized. Some perceived that discrimination and harassment were a current concern within medical physics, while some either perceived that they were not a concern or that discrimination positively affected women and minoritized populations. Many participants shared personal experiences of discrimination and harassment, including those related to unequal compensation, discrimination against mothers, discrimination during the hiring process, gender-biased assumptions about behaviors or goals, communication biases, and overt and persistent sexual harassment.

CONCLUSIONS

There is an urgent need to acknowledge, better understand, and address gender-based discrimination and sexual harassment in the field of medical physics.

Mediators of Racial Disparities in Heart Dose Among Whole Breast Radiotherapy Patients

BACKGROUND

Racial disparities in survival of patients with cancer motivate research to quantify treatment disparities and evaluate multilevel determinants. Previous research has not evaluated cardiac radiation dose in large cohorts of breast cancer patients by race nor examined potential causes or implications of dose disparities.

METHODS

We used a statewide consortium database to consecutively sample 8750 women who received whole breast radiotherapy between 2012 and 2018. We generated laterality- and fractionation-specific models of mean heart dose. We generated patient- and facility-level models to estimate race-specific cardiac doses. We incorporated our data into models to estimate disparities in ischemic cardiac event development and death. All statistical tests were 2-sided.

RESULTS

Black and Asian race independently predicted higher mean heart dose for most laterality-fractionation groups, with disparities of up to 0.42 Gy for Black women and 0.32 Gy for Asian women (left-sided disease and conventional fractionation: 2.13 Gy for Black women vs 1.71 Gy for White women, P < .001, 2-sided; left-sided disease and accelerated fractionation: 1.59 Gy for Asian women vs 1.27 Gy for White women, P = .002). Patient clustering within facilities explained 22%-30% of the variability in heart dose. The cardiac dose disparities translated to estimated excesses of up to 2.6 cardiac events and 1.3 deaths per 1000 Black women and 0.7 cardiac events and 0.3 deaths per 1000 Asian women vs White women.

CONCLUSIONS

Depending on laterality and fractionation, Asian women and Black women experience higher cardiac doses than White women. This may translate into excess radiation-associated ischemic cardiac events and deaths. Solutions include addressing inequities in baseline cardiac risk factors and facility-level availability and use of radiation technologies.

Identifying Patients Whose Symptoms Are Underrecognized During Treatment With Breast Radiotherapy

Importance

Understanding whether physicians accurately detect symptoms in patients with breast cancer is important because recognition of symptoms facilitates supportive care, and clinical trials often rely on physician assessments using Common Toxicity Criteria for Adverse Events (CTCAE).

Objective

To compare the patient-reported outcomes (PROs) of patients with breast cancer who received radiotherapy from January 1, 2012, to March 31, 2020, with physicians' CTCAE assessments to assess underrecognition of symptoms.

Design, Setting, and Participants

This cohort study included a total of 29 practices enrolled in the Michigan Radiation Oncology Quality Consortium quality initiative. Of 13 725 patients with breast cancer who received treatment with radiotherapy after undergoing lumpectomy, 9941 patients (72.4%) completed at least 1 PRO questionnaire during treatment with radiotherapy and were evaluated for the study. Of these, 9868 patients (99.3%) were matched to physician CTCAE assessments that were completed within 3 days of the PRO questionnaires.

Exposures

Patient and physician ratings of 4 symptoms (pain, pruritus, edema, and fatigue) were compared.

Main Outcomes and Measures

We used multilevel multivariable logistic regression to evaluate factors associated with symptom underrecognition, hypothesizing that it would be more common in racial and ethnic minority groups.

Results

Of 9941 patients, all were female, 1655 (16.6%) were Black, 7925 (79.7%) were White, and 361 (3.6%) had Other race and ethnicity (including American Indian/Alaska Native, Arab/Middle Eastern, and Asian), either as self-reported or as indicated in the electronic medical record. A total of 1595 (16.0%) were younger than 50 years, 2874 (28.9%) were age 50 to 59 years, 3353 (33.7%) were age 60 to 69 years, and 2119 (21.3%) were 70 years or older. Underrecognition of symptoms existed in 2094 of 6781 (30.9%) observations of patient-reported moderate/severe pain, 748 of 2039 observations (36.7%) of patient-reported frequent pruritus, 2309 of 4492 observations (51.4%) of patient-reported frequent edema, and 390 of 2079 observations (18.8%) of patient-reported substantial fatigue. Underrecognition of at least 1 symptom occurred at least once for 2933 of 5510 (53.2%) of those who reported at least 1 substantial symptom. Factors independently associated with underrecognition were younger age (younger than 50 years compared with 60-69 years: odds ratio [OR], 1.35; 95% CI, 1.14-1.59; P < .001; age 50-59 years compared with 60-69 years: OR, 1.19; 95% CI, 1.03-1.37; P = .02), race (Black individuals compared with White individuals: OR, 1.56; 95% CI 1.30-1.88; P < .001; individuals with Other race or ethnicity compared with White individuals: OR, 1.52; 95% CI, 1.12-2.07; P = .01), conventional fractionation (OR, 1.26; 95% CI, 1.10-1.45; P = .002), male physician sex (OR, 1.54; 95% CI, 1.20-1.99; P = .002), and 2-field radiotherapy (without a supraclavicular field) (OR, 0.80; 95% CI, 0.67-0.97; P = .02).

Conclusions and Relevance

The results of this cohort study suggest that PRO collection may be essential for trials because relying on the CTCAE to detect adverse events may miss important symptoms. Moreover, since physicians in this study systematically missed substantial symptoms in certain patients, including younger patients and Black individuals or those of Other race and ethnicity, improving symptom detection may be a targetable mechanism to reduce disparities.

A roadmap to clinical trials for FLASH

While FLASH radiation therapy is inspiring enthusiasm to transform the field, it is neither new nor well understood with respect to the radiobiological mechanisms. As FLASH clinical trials are designed, it will be important to ensure we can deliver dose consistently and safely to every patient. Much like hyperthermia and proton therapy, FLASH is a promising new technology that will be complex to implement in the clinic and similarly will require customized credentialing for multi‐institutional clinical trials. There is no doubt that FLASH seems promising, but many technologies that we take for granted in conventional radiation oncology, such as rigorous dosimetry, 3D treatment planning, volumetric image guidance, or motion management, may play a major role in defining how to use, or whether to use, FLASH radiotherapy. Given the extended time frame for patients to experience late effects, we recommend moving deliberately but cautiously forward toward clinical trials. In this paper, we review the state of quality assurance and safety systems in FLASH, identify critical pre‐clinical data points that need to be defined, and suggest how lessons learned from previous technological advancements will help us close the gaps and build a successful path to evidence‐driven FLASH implementation.

Gender Equity in Radiation Oncology: Culture Change is a Marathon, not a Sprint

The specialty of radiation oncology's gender diversity is lagging other medical specialties. The lack of gender diversity in radiation oncology has been demonstrated at all stages of career, from medical schools to department chairs. Multiple articles have demonstrated literature-based benefits of inclusion of a diverse group of female colleagues. This editorial is intended to note areas of progress and highlight resources available to support gender equity in the field of radiation oncology.

Comparative Effectiveness Analysis of 3D-Conformal Radiation Therapy Versus Intensity Modulated Radiation Therapy (IMRT) in a Prospective Multicenter Cohort of Patients With Breast Cancer

PURPOSE

Simple intensity modulation of radiation therapy reduces acute toxicity compared with 2-dimensional techniques in adjuvant breast cancer treatment, but it remains unknown whether more complex or inverse-planned intensity modulated radiation therapy (IMRT) offers an advantage over forward-planned, 3-dimensional conformal radiation therapy (3DCRT).

METHODS AND MATERIALS

Using prospective data regarding patients receiving adjuvant whole breast radiation therapy without nodal irradiation at 23 institutions from 2011 to 2018, we compared the incidence of acute toxicity (moderate-severe pain or moist desquamation) in patients receiving 3DCRT versus IMRT (either inverse planned or, if forward-planned, using ≥5 segments per gantry angle). We evaluated associations between technique and toxicity using multivariable models with inverse-probability-of-treatment weighting, adjusting for treatment facility as a random effect.

RESULTS

Of 1185 patients treated with 3DCRT and conventional fractionation, 650 (54.9%) experienced acute toxicity; of 774 treated with highly segmented forward-planned IMRT, 458 (59.2%) did; and of 580 treated with inverse-planned IMRT, 245 (42.2%) did. Of 1296 patients treated with hypofractionation and 3DCRT, 432 (33.3%) experienced acute toxicity; of 709 treated with highly segmented forward-planned IMRT, 227 (32.0%) did; and of 623 treated with inverse-planned IMRT, 164 (26.3%) did. On multivariable analysis with inverse-probability-of-treatment weighting, the odds ratio for acute toxicity after inverse-planned IMRT versus 3DCRT was 0.64 (95% confidence interval, 0.45-0.91) with conventional fractionation and 0.41 (95% confidence interval, 0.26-0.65) with hypofractionation.

CONCLUSIONS

This large, prospective, multicenter comparative effectiveness study found a significant benefit from inverse-planned IMRT compared with 3DCRT in reducing acute toxicity of breast radiation therapy. Future research should identify the dosimetric differences that mediate this association and evaluate cost-effectiveness.

The impact of chemotherapy on toxicity and cosmetic outcome in patients receiving whole breast irradiation: an analysis within a state-wide quality consortium

PURPOSE

We investigated whether the use of chemotherapy prior to whole breast irradiation (WBI) using either conventional fractionation (CWBI) or hypofractionation (HWBI) is associated with increased toxicity or worse cosmetic outcome compared to WBI alone.

METHODS AND MATERIALS

We identified 6,754 patients who received WBI alone (without a third field covering the superior axillary and supraclavicular nodal regions) with data prospectively collected in a state-wide consortium. We reported rates of four toxicity outcomes: physician-reported acute moist desquamation, patient-reported acute moderate/severe breast pain, a composite acute toxicity measure (including moist desquamation and either patient-reported or physician-reported moderate/significant breast pain), and physician-reported impaired cosmetic outcome at one year following WBI. Successive multivariable models were constructed to estimate the impact of chemotherapy on these outcomes.

RESULTS

Rates of moist desquamation, patient-reported pain, composite acute toxicity, and impaired cosmetic outcome were 23%, 34%, 42%, and 10% for 2,859 patients receiving CWBI and 13%, 28%, 31%, and 11% for 3,895 patients receiving HWBI. Receipt of chemotherapy prior to CWBI was not associated with higher rates of patient-reported pain, composite acute toxicity, or impaired cosmetic outcome compared to CWBI without chemotherapy but was associated with more moist desquamation (OR=1.32 [1.07-1.63], p=0.01). Receipt of chemotherapy prior to HWBI was not associated with higher rates of any of the four toxicity outcomes compared to HWBI alone.

CONCLUSIONS

In this cohort, use of chemotherapy prior to WBI was generally well tolerated. CWBI with chemotherapy, but not to HWBI with chemotherapy, was associated with higher rates of moist desquamation. Rates of acute breast pain and impaired cosmetic outcome at one year were comparable in patients receiving chemotherapy prior to either CWBI or HWBI. These data support the use of HWBI following chemotherapy.

A qualitative investigation of resilience and well-being among medical physics residents

Purpose

Medical physics residents (MPRs) will define and shape the future of physics in medicine. We sought to better understand the residency experience, as related to resilience and well‐being, through the lens of current MPRs and medical physicists (MPs) working with residents.

Methods and materials

From February–May 2019, we conducted 32, 1‐h, confidential, semi‐structured interviews with MPs either currently enrolled in an accredited residency (n = 16) or currently employed by a department with an accredited residency (n = 16). Interviews centered on the topics of mentorship, work/life integration, and discrimination. Qualitative analysis methods were used to derive key themes from the interview transcripts.

Results

With regard to the medical physics residency experience, four key themes emerged during qualitative analysis: the demanding nature of medical physics residencies, the negative impacts of residency on MPRs during training and beyond, strategies MPRs use to cope with residency stress, and the role of professional societies in addressing residency‐related change.

Conclusions

Residency training is a stress‐inducing time in the path to becoming a board‐certified MP. By uncovering several sources of this stress, we have identified opportunities to support the resiliency and well‐being of MPs in training through recommendations by professional societies, programmatic changes, and interventions at the department and residency program director level for residency programs, as well as strategies that MPRs themselves can use to support well‐being on their career journey.

The Michigan Radiation Oncology Quality Consortium: A Novel Initiative to Improve the Quality of Radiation Oncology Care

PURPOSE

Numerous quality measures have been proposed in radiation oncology, and initiatives to improve access to high-complexity care, quality, and equity are needed. We describe the design and evaluate impact of a voluntary statewide collaboration for quality improvement in radiation oncology initiated a decade ago.

METHODS AND MATERIALS

We evaluate compliance before and since implementation of annual metrics for quality improvement, using an observational dataset with information from over 20,000 patients treated in the 28 participating radiation oncology practices. At thrice-yearly meetings, experts have spoken regarding trends within the field and inspired discussions regarding potential targets for quality improvement. Blinded data on practices at various sites have been provided. Following Standards for Quality Improvement Reporting Excellence (SQUIRE) guidelines, we describe the approach and measures the program has implemented. To evaluate impact, we compare compliance at baseline and now with active measures using mixed effects regression models with site-level random effects.

RESULTS

Compliance has increased, including use of guideline-concordant hypofractionated radiotherapy, doses to targets/normal tissues, motion management, and consistency in delineating and naming contoured structures (a precondition for quality evaluation). For example, use of guideline-concordant hypofractionation for breast cancer increased from 47% to 97%, adherence to target coverage goals and heart dose limits for dose increased from 46% to 86%, motion assessment in patients with lung cancer increased from 52% to 94%, and use of standard nomenclature increased from 53% to 82% for lung patients and from 80% to 94% for breast patients (all p<0.001).

CONCLUSIONS

Although observational analysis cannot fully exclude secular trends, contextual data revealing slow uptake of best practices elsewhere in the US and qualitative feedback from participants suggests that this initiative has improved the consistency, efficiency, and quality of radiation oncology care in its member practices and may be a model for oncology quality improvement more generally.

A Safe and Practical Cycle for Team-Based Development and Implementation of In-House Clinical Software

Purpose

Due to a gap in published guidance, we describe our robust cycle of in-house clinical software development and implementation, which has been used for years to facilitate the safe treatment of all patients in our clinics.

Methods and Materials

Our software development and implementation cycle requires clarity in communication, clearly defined roles, thorough commissioning, and regular feedback. Cycle phases include design requirements and use cases, development, physics evaluation testing, clinical evaluation testing, and full clinical release. Software requirements, release notes, test suites, and a commissioning report are created and independently reviewed before clinical use. Software deemed to be high-risk, such as those that are writable to a database, incorporate the use of a formal, team-based hazard analysis. Incident learning is used to both guide initial development and improvements as well as to monitor the safe use of the software.

Results

Our standard process builds in transparency and establishes high expectations in the development and use of custom software to support patient care. Since moving to a commercial planning system platform in 2013, we have applied our team-based software release process to 16 programs related to scripting in the treatment planning system for the clinic.

Conclusions

The principles and methodology described here can be implemented in a range of practice settings regardless of whether or not dedicated resources are available for software development. In addition to teamwork with defined roles, documentation, and use of incident learning, we strongly recommend having a written policy on the process, using phased testing, and incorporating independent oversight and approval before use for patient care. This rigorous process ensures continuous monitoring for and mitigatation of any high risk hazards.

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. The CBCT image analysis framework was used to compare periodic QA results among 23 linear accelerators (linacs) from seven institutions. The CBCT image quality metrics (geometric distortion, spatial resolution, contrast, HU constancy, uniformity and noise) data are plotted as a function of means with the upper and lower control limits compared to the linac acceptance criteria and AAPM recommendations. For example, mean geometric distortion and HU constancy metrics were found to be 0.13 mm (TG142 recommendation: ≤2 mm) and 13.4 respectively (manufacturer acceptance specification: ≤±50).Image upload and analysis process was fully automated using a MATLAB-based platform. This analysis enabled a quantitative, longitudinal assessment of the performance of quality metrics which were also compared across 23 linacs. For key CBCT parameters such as uniformity, contrast, and HU constancy, all seven institutions used stricter goals than what would be recommended based on the analysis of the upper and lower control limits. These institutional goals were also found to be stricter than that found in AAPM published guidance. This work provides a reference that could be used to machine-specific optimized tolerance of CBCT image maintenance via control charts to monitor performance we well as the sensitivity of different tests in support of a broader quality assurance program. To ensure the daily image quality needed for patient care, the optimized statistical QA metrics recommended to using along with risk-based QA.

A simulation study of ionizing radiation acoustic imaging (iRAI) as a real-time dosimetric technique for ultra-high dose rate radiotherapy (UHDR-RT)

PURPOSE

Electron-based ultra-high dose rate radiation therapy (UHDR-RT), also known as Flash-RT, has shown the ability to improve the therapeutic index in comparison to conventional radiotherapy (CONV-RT) through increased sparing of normal tissue. However, the extremely high dose rates in UHDR-RT have raised the need for accurate real-time dosimetry tools. This work aims to demonstrate the potential of the emerging technology of Ionized Radiation Acoustic Imaging (iRAI) through simulation studies and investigate its characteristics as a promising relative in vivo dosimetric tool for UHDR-RT.

METHODS

The detection of induced acoustic waves following a single UHDR pulse of a modified 6 MeV 21EX Varian Clinac in a uniform porcine gelatin phantom that is brain-tissue equivalent was simulated for an ideal ultrasound transducer. The full 3D dose distributions in the phantom for a 1 × 1 cm2 field were simulated using EGSnrc (BEAMnrc∖DOSXYZnrc) Monte Carlo (MC) codes. The relative dosimetry simulations were verified with dose experimental measurements using Gafchromic films. The spatial dose distribution was converted into an initial pressure source spatial distribution using the medium-dependent dose-pressure relation. The MATLAB-based toolbox k-Wave was then used to model the propagation of acoustic waves through the phantom and perform time-reversal (TR)-based imaging reconstruction. The effect of the various linear accelerator (linac) operating parameters, including linac pulse duration and pulse repetition rate (frequency), were investigated as well.

RESULTS

The MC dose simulation results agreed with the film measurement results, specifically at the central beam region up to 80% dose within approximately 5% relative error for the central profile region and a local relative error of <6% for percentage dose depth. IRAI-based FWHM of the radiation beam was within approximately 3 mm relative to the MC-simulated beam FWHM at the beam entrance. The real-time pressure signal change agreed with the dose changes proving the capability of the iRAI for predicting the beam position. IRAI was tested through 3D simulations of its response to be based on the temporal changes in the linac operating parameters on a dose per pulse basis as expected theoretically from the pressure-dose proportionality. The pressure signal amplitude obtained through 2D simulations was proportional to the dose per pulse. The instantaneous pressure signal amplitude decreases as the linac pulse duration increases, as predicted from the pressure wave generation equations, such that the shorter the linac pulse the higher the signal and the better the temporal (spatial) resolutions of iRAI. The effect of the longer linac pulse duration on the spatial resolution of the 3D constructed iRAI images was corrected for linac pulse deconvolution. This correction has improved the passing rate of the 1%/1 mm gamma test criteria, between the pressure-constructed and dosimetric beam characteristics, to as high as 98%.

CONCLUSIONS

A full simulation workflow was developed for testing the effectiveness of iRAI as a promising relative dosimetry tool for UHDR-RT radiation therapy. IRAI has shown the advantage of 3D dose mapping through the dose signal linearity and, hence, has the potential to be a useful dosimeter at depth dose measurement and beam localization and, hence, potentially for in vivo dosimetry in UHDR-RT.

Report of AAPM Task Group 219 on independent calculation-based dose/MU verification for IMRT

Independent verification of the dose per monitor unit (MU) to deliver the prescribed dose to a patient has been a mainstay of radiation oncology quality assurance (QA). We discuss the role of secondary dose/MU calculation programs as part of a comprehensive QA program. This report provides guidelines on calculation-based dose/MU verification for intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) provided by various modalities. We provide a review of various algorithms for "independent/second check" of monitor unit calculations for IMRT/VMAT. The report makes recommendations on the clinical implementation of secondary dose/MU calculation programs; on commissioning and acceptance of various commercially available secondary dose/MU calculation programs; on benchmark QA and periodic QA; and on clinically reasonable action levels for agreement of secondary dose/MU calculation programs.

Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non-equilibrium conditions

Small-field dosimetry used in advance treatment technologies poses challenges due to loss of lateral charged particle equilibrium (LCPE), occlusion of the primary photon source, and the limited choice of suitable radiation detectors. These challenges greatly influence dosimetric accuracy. Many high-profile radiation incidents have demonstrated a poor understanding of appropriate methodology for small-field dosimetry. These incidents are a cause for concern because the use of small fields in various specialized radiation treatment techniques continues to grow rapidly. Reference and relative dosimetry in small and composite fields are the subject of the International Atomic Energy Agency (IAEA) dosimetry code of practice that has been published as TRS-483 and an AAPM summary publication (IAEA TRS 483; Dosimetry of small static fields used in external beam radiotherapy: An IAEA/AAPM International Code of Practice for reference and relative dose determination, Technical Report Series No. 483; Palmans et al., Med Phys 45(11):e1123, 2018). The charge of AAPM task group 155 (TG-155) is to summarize current knowledge on small-field dosimetry and to provide recommendations of best practices for relative dose determination in small megavoltage photon beams. An overview of the issue of LCPE and the changes in photon beam perturbations with decreasing field size is provided. Recommendations are included on appropriate detector systems and measurement methodologies. Existing published data on dosimetric parameters in small photon fields (e.g., percentage depth dose, tissue phantom ratio/tissue maximum ratio, off-axis ratios, and field output factors) together with the necessary perturbation corrections for various detectors are reviewed. A discussion on errors and an uncertainty analysis in measurements is provided. The design of beam models in treatment planning systems to simulate small fields necessitates special attention on the influence of the primary beam source and collimating devices in the computation of energy fluence and dose. The general requirements for fluence and dose calculation engines suitable for modeling dose in small fields are reviewed. Implementations in commercial treatment planning systems vary widely, and the aims of this report are to provide insight for the medical physicist and guidance to developers of beams models for radiotherapy treatment planning systems.

Contemporary Practice Patterns for Palliative Radiation Therapy of Bone Metastases: Impact of a Quality Improvement Project on Extended Fractionation

PURPOSE

Radiation therapy effectively palliates bone metastases, although variability exists in practice patterns. National recommendations advocate against using extended fractionation (EF) with courses greater than 10 fractions. We previously reported EF use of 14.8%. We analyzed practice patterns within a statewide quality consortium to assess EF use in a larger patient population after implementation of a quality measure focused on reducing EF.

METHODS AND MATERIALS

Patients treated for bone metastases within a statewide radiation oncology quality consortium were prospectively enrolled from March 2018 through October 2020. The EF quality metric was implemented March 1, 2018. Data on patient, physician, and facility characteristics; fractionation schedules; and treatment planning and delivery techniques were collected. Multivariable binary logistic regression was used to assess EF.

RESULTS

Twenty-eight facilities enrolled 1445 consecutive patients treated with 1934 plans. The median number of treatment plans per facility was 52 (range, 7-307). Sixty different fractionation schedules were used. EF was delivered in 3.4% of plans. Initially, EF use was lower than expected and remained low over time. Significant predictors for EF use included complicated metastasis (odds ratio [OR], 2.04; 95% confidence interval [CI], 1.04-4.02; P = .04), lack of associated central nervous system or visceral disease (OR, 2.27; 95% CI, 1.2-4.2; P = .01), nonteaching versus teaching facilities (OR, 8.97; 95% CI, 2.1-38.5; P < .01), and treating physicians with more years in practice (OR, 12.82; 95% CI, 3.9-42.4; P < .01).

CONCLUSIONS

Within a large, prospective population-based data set, fractionation schedules for palliative radiation therapy of bone metastases remain highly variable. Resource-intensive treatments including EF persist, although EF use was low after implementation of a quality measure. Complicated metastases, lack of central nervous system or visceral disease, and treatment at nonteaching facilities or by physicians with more years in practice significantly predict use of EF. These results support ongoing efforts to more clearly understand and address barriers to high-value radiation approaches in the palliative setting.

Abstract GS3-07: Identifying patients whose symptoms are under-recognized during breast radiotherapy: Comparison of patient and physician reports of toxicity in a multicenter cohort

BACKGROUND: Evaluating whether physicians (MDs) accurately detect symptoms in patients (pts) is important because recognition of symptoms facilitates supportive care and because clinical trials often rely on MD assessments using the Common Toxicity Criteria for Adverse Events (CTCAE).

METHODS: Breast cancer pts who received radiotherapy (RT) after lumpectomy at 29 practices were enrolled in a quality initiative, MROQC. Of 13,725 pts who completed RT between 1/1/2012 and 3/31/2020, 9,941 completed at least one pt-reported outcomes (PRO) questionnaire during RT. Where MD CTCAE assessments were available within 3 days of PRO evaluation, pt and MD ratings of 4 symptoms were compared. Pts reported breast pain via an approved modification of the Brief Pain Inventory, asking for ratings in the last 24 hours of pain at its worst, least, average, and “right now.” MDs were deemed to under-recognize pain when pts reported moderate pain (score 4-6) but MDs graded pain as 0 (absent) on the CTCAE, or when pts reported severe pain (score 7-10) but MDs’ CTCAE grade was ≤1. Bother from pruritis and edema were measured by modified scaled measures adapted from the Skindex. MDs were deemed to under-recognize pruritus and edema if they graded these as absent (grade 0) when pts reported bother often or all of the time from itching or swelling, respectively. MDs were deemed to under-recognize fatigue if they graded fatigue as absent (grade 0) when pts reported having significant fatigue most of the time or always.We describe the proportion of pts for whom under-recognition of at least 1 of these 4 symptoms occurred at least once during the treatment course and use multivariable logistic regression to evaluate predictors of this under-recognition, hypothesizing that it would be more common in racial minorities.

RESULTS: 3,434/9,940 pts (34.5%) reported substantial breast pain, 3,039/9,923 (30.6%) frequent bother from pruritus, 2,363/9,906 (23.9%) frequent bother from edema, and 2,209/8,860 (24.9%) severe fatigue. We could evaluate under-recognition in 9,868 pts, with 37,593 independent paired observations of pt and MD reports (35,797 on the same date and 1,796 within 3 days). Under-recognition existed in 2,094/6,781 (30.9%) observations of pt-reported moderate/severe pain, 748/2,039 (36.7%) of pt-reported frequent pruritis, 2,309/4,492 (51.4%) of pt-reported frequent edema, and 390/2,079 (18.8%) of pt-reported severe fatigue. Under-recognition of at least 1 of these 4 symptoms occurred at least once during the pt’s treatment course for 2,933/5,510 (53.2%) of the pts who reported at least 1 substantial symptom during RT.Factors independently associated with under-recognition were (Table): younger age (OR=1.4 and 1.2 for &lt;50 and 50-59 vs. 60-69, respectively), black or other race (OR=1.9 and 1.8 vs white, respectively), conventional fractionation (OR=1.2), not having a supraclavicular field (OR=1.3) and being treated at an academic center (OR=1.1).

CONCLUSIONS: PRO collection appears essential for trials because relying on the CTCAE to detect adverse events may miss important symptoms. Moreover, since MDs systematically miss substantial symptoms in certain patients, including pts who are younger or of black or other race, improving symptom detection may be a targetable mechanism to reduce disparities in RT experiences and outcomes.

Multivariable model of symptom under-recognitionOR95% CIpAge--0.001&lt;501.351.15-1.58&lt;0.00150-591.211.06-1.390.00660-691 (ref)--70+1.050.89-1.240.55Body Mass Index--0.67Underweight (&lt;18.5).790.52-1.200.27Normal(18.5-&lt;25).990.84-1.150.86Overweight (25-&lt;30)1 (ref)--Obesity I (30-&lt;35)1.010.87-1.180.87Obesity II (35-&lt;40)1.050.88-1.250.61Obesity III (40+)1.110.92-1.340.27Race--&lt;0.001White1 (ref)--Black1.921.65-2.23&lt;0.001Asian1.320.84-2.080.23Other1.821.24-2.660.002Supraclavicular field used (yes vs no)0.800.68-0.950.01Fractionation (conventionalvs hypo fractionation)1.151.02-1.300.02Boost to tumor bed (yes vs no)0.950.80-1.120.53Facility(Academic vs Community)1.131.01-1.270.04

Citation Format: Reshma Jagsi, Kent A. Griffith, Frank Vicini, Thomas Boike, Michael Dominello, Gregory Gustafson, James A. Hayman, Jean M. Moran, Jeffrey Radawski, Eleanor Walker, Lori J. Pierce, on behalf of MROQC, the Michigan Radiation Oncology Quality Consortium. Identifying patients whose symptoms are under-recognized during breast radiotherapy: Comparison of patient and physician reports of toxicity in a multicenter cohort [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr GS3-07.

Application of radiochromic gel dosimetry to commissioning of a megavoltage research linear accelerator for small-field animal irradiation studies

PURPOSE

To develop and implement an efficient and accurate commissioning procedure for small-field static beam animal irradiation studies on an MV research linear accelerator (Linatron-M9) using radiochromic gel dosimetry.

MATERIALS

The research linear accelerator (Linatron-M9) is a 9 MV linac with a static fixed collimator opening of 5.08 cm diameter. Lead collimators were manually placed to create smaller fields of 2 × 2 cm² , 1 × 1 cm² , and 0.5 × 0.5 cm² . Relative dosimetry measurements were performed, including profiles, percent depth dose (PDD) curves, beam divergence, and relative output factors using various dosimetry tools, including a small volume ionization chamber (A14), GAFCHROMIC™ EBT3 film, and Clearview gel dosimeters. The gel dosimeter was used to provide a 3D volumetric reference of the irradiated fields. The Linatron profiles and relative output factors were extracted at a reference depth of 2 cm with the output factor measured relative to the 2 × 2 cm² reference field. Absolute dosimetry was performed using A14 ionization chamber measurements, which were verified using a national standards laboratory remote dosimetry service.

RESULTS

Absolute dosimetry measurements were confirmed within 1.4% (k = 2, 95% confidence = 5%). The relative output factor of the small fields measured with films and gels agreed with a maximum relative percent error difference between the two methods of 1.1 % for the 1 × 1 cm² field and 4.3 % for the 0.5 × 0.5 cm² field. These relative errors were primarily due to the variability in the collimator positioning. The measured beam profiles demonstrated excellent agreement for beam size (measured as FWHM), within approximately 0.8 mm (or less). Film measurements were more accurate in the penumbra region due to the film's finer resolution compared with the gel dosimeter. Following the van Dyk criteria, the PDD values of the film and gel measurements agree within 11% in the buildup region starting from 0.5 cm depth and within 2.6 % beyond maximum dose and into the fall-off region for depths up to 5 cm. The 2D beam profile isodose lines agree within 0.5 mm in all regions for the 0.5 × 0.5 cm² and the 1 × 1 cm² fields and within 1 mm for the larger field of 2 × 2 cm² . The 2D PDD curves agree within approximately 2% of the maximum in the typical therapy region (1-4 cm) for the 1 × 1 cm² and 2 × 2 cm² and within 5% for the 0.5 × 0.5 cm² field.

CONCLUSION

This work provides a commissioning process to measure the beam characteristics of a fixed beam MV accelerator with detailed dosimetric evaluation for its implementation in megavoltage small animal irradiation studies. Radiochromic gel dosimeters are efficient small-field relative dosimetry tools providing 3D dose measurements allowing for full representation of dose, dosimeter misalignment corrections and high reproducibility with low inter-dosimeter variability. Overall, radiochromic gels are valuable for fast, full relative dosimetry commissioning in comparison to films for application in high-energy small-field animal irradiation studies.

Toward Improving Patients' Experiences of Acute Toxicity From Breast Radiotherapy: Insights From the Analysis of Patient-Reported Outcomes in a Large Multicenter Cohort

PURPOSE

Understanding acute toxicities after whole-breast radiotherapy is important to inform patients, guide treatment decisions, and target supportive care. We evaluated patient-reported outcomes prospectively collected from a cohort of patients with breast cancer.

METHODS

We describe the maximal toxicity reported by 8,711 patients treated between 2012 and 2019 at 27 practices. Multivariable models identified characteristics associated with (1) breast pain, (2) bother from itching, stinging/burning, swelling, or hurting of the treated breast, and (3) fatigue within 7 days of completing whole-breast radiotherapy.

RESULTS

Moderate or severe breast pain was reported by 3,233 (37.1%): 1,282 (28.9%) of those receiving hypofractionation and 1,951 (45.7%) of those receiving conventional fractionation. Frequent bother from at least one breast symptom was reported by 4,424 (50.8%): 1,833 (41.3%) after hypofractionation and 2,591 (60.7%) after conventional fractionation. Severe fatigue was reported by 2,008 (23.1%): 843 (19.0%) after hypofractionation and 1,165 (27.3%) after conventional fractionation. Among patients receiving hypofractionated radiotherapy, younger age (P < .001), higher body mass index (BMI; P < .001), Black (P < .001) or other race (P = .002), smoking status (P < .001), larger breast volume (P = .002), lack of chemotherapy receipt (P = .004), receipt of boost treatment (P < .001), and treatment at a nonteaching center predicted breast pain. Among patients receiving conventionally fractionated radiotherapy, younger age (P < .001), higher BMI (P = .003), Black (P < .001) or other race (P = .002), diabetes (P = .001), smoking status (P < .001), and larger breast volume (P < .001) predicted breast pain.

CONCLUSION

In this large observational data set, substantial differences existed according to radiotherapy dose fractionation. Race-related differences in pain existed despite controlling for multiple other factors; additional research is needed to understand what drives these differences to target potentially modifiable factors. Intensifying supportive care may be appropriate for subgroups identified as being vulnerable to greater toxicity.

The Fusion of Incident Learning and Failure Mode and Effects Analysis for Data-Driven Patient Safety Improvements

PURPOSE

Incident learning is a critical part of the quality improvement process for all radiation therapy clinics. Failure mode and effects analysis has also been adopted as a hazard analysis method within the field of radiation oncology based on the recommendations of American Association of Physicists in Medicine Task Group 100. In this work, we demonstrate a fusion of these techniques that is efficient and transferrable to all types of clinics and that allows data-driven targeting of the highest risk error types.

METHODS AND MATERIALS

Four clinical physicists recorded safety events detected during physics treatment plan quality assurance over a 27-month period. Events were sorted into the broad categories of either a documentation or plan construction error. Events were further stratified into subcategories until sufficiently discriminated against for analysis. Event risks were quantified using reduced-resolution TG-100 severity scores combined with observed occurrence rates. The highest risk categories were examined for intervention strategies.

RESULTS

A total of 871 events were identified over the study period. Of these, 652 (74.9%) were classified as low severity, 178 (20.4%) as medium severity, and 41 (4.7%) as high severity. Four of the top 5 ranked categories could be targeted by a preplanning chart rounds. Several of the categories could be targeted by additional automation in the planning and QA processes.

CONCLUSIONS

The retrospective classification and risk analysis of safety events allows clinics to design targeted workflow and quality assurance changes aimed at reducing the occurrence of high-risk events. The method presented here leverages incident learning efforts that many clinics are already performing, allows the severity of events to be efficiently assigned, and generates actionable results without requiring a complete failure mode and effects analysis.

The state of gender diversity in medical physics

The purpose of this study was to quantify gender diversity in leadership positions within the field of medical physics, as well as within award categories and other recognitions by the American Association of Physicists in Medicine. The April 2019 PDF version of the AAPM membership directory was searched for all users self‐reporting as holding a leadership position at their place of employment, those elected to leadership positions within the AAPM, those serving as chair of an AAPM council, and those listed as having received an award or other such recognition from AAPM (beginning in 1972 with the William D. Coolidge Award). Historical data for these categories were obtained from archived membership directories on the AAPM website. The AAPM website was also used to identify members who have served on the Medical Physics Editorial Board. The Commission on Accreditation of Medical Physics Education Programs (CAMPEP) website was used to identify the current directors of graduate and residency programs (as of July 2019). Because gender was not a reported field in any of these categories, gender was assigned by reviewing names and photographs. Percentage representation in these respects was compared to the overall percentage of women in the AAPM in 2019 (23.3%) and reported the number of women working as medical physicists globally (29.8%). Within the AAPM, the percentage of women reporting clinical leadership roles is 12.0% within the US, 13.6% in Canada, and 18.0% in all other countries combined. Women comprise only 7.5% of CAMPEP graduate program directors and 21.5% of residency program directors. The percentage of female presidents in AAPM is 8.1%. A woman has never served as Editor‐in‐Chief of Medical Physics, and the average for the past 10 yr for female board membership is 13.6%. With the exception of the John R. Cameron Young Investigators Symposium Award, the percentage of all female AAPM awardees is less than the percentage of women AAPM members. The lowest percentage of female representation within AAPM is among council chairs with only one woman having held a chair position out of 42 positions (2.4%) from 1970 to July 2019. Similar to the traditional discipline of physics, medical physics displays a clear gender disparity with regard to leadership positions, both within educational training programs and the AAPM. Further investigation into the demographics of the field and psychosocial factors affecting medical physicists may help to elucidate the origin of these disparities and inform strategies to address them.

Combination of a Big Data Analytics Resource System With an Artificial Intelligence Algorithm to Identify Clinically Actionable Radiation Dose Thresholds for Dysphagia in Head and Neck Patients

Purpose

We combined clinical practice changes, standardizations, and technology to automate aggregation, integration, and harmonization of comprehensive patient data from the multiple source systems used in clinical practice into a big data analytics resource system (BDARS). We then developed novel artificial intelligence algorithms, coupled with the BDARS, to identify structure dose volume histograms (DVH) metrics associated with dysphagia.

Methods and Materials

From the BDARS harmonized data of ≥22,000 patients, we identified 132 patients recently treated for head and neck cancer who also demonstrated dysphagia scores that worsened from base line to a maximum grade ≥2. We developed a method that used both physical and biologically corrected (α/β = 2.5) DVH curves to test both absolute and percentage volume based DVH metrics. Combining a statistical categorization algorithm with machine learning (SCA-ML) provided more extensive detailing of response threshold evidence than either approach alone. A sensitivity guided, minimum input, machine learning (ML) model was iteratively constructed to identify the key structure DVH metric thresholds.

Results

Seven swallowing structures producing 738 candidate DVH metrics were ranked for association with dysphagia using SCA-ML scoring. Structures included superior pharyngeal constrictor (SPC), inferior pharyngeal constrictor (IPC), larynx, and esophagus. Bilateral parotid and submandibular gland (SG) structures were categorized by relative mean dose (eg, SG_high, SG_low) as a dose versus tumor centric analog to contra and ipsilateral designations. Structure DVH metrics with high SCA-ML scores included the following: SPC: D20% (equivalent dose [EQD2] Gy) ≥47.7; SPC: D25% (Gy) ≥50.4; IPC: D35% (Gy) ≥61.7; parotid_low: D60% (Gy) ≥13.2; and SG_high: D35% (Gy) ≥61.7. Larynx: D25% (Gy) ≥21.2 and SG_low: D45% ≥28.2 had high SCA-ML scores but were segmented on less than 90% of plans. A model based on SPC: D20% (EQD2 Gy) alone had sensitivity and area under the curve of 0.88 ± 0.13 and 0.74 ± 0.17, respectively.

Conclusions

This study provides practical demonstration of combining big data with artificial intelligence to increase volume of evidence in clinical learning paradigms.

Mentorship in Radiation Oncology: Role of Gender Diversity in Abstract Presenting and Senior Author Dyads on Subsequent High-Impact Publications

Purpose

To generate insights regarding the role of gender in research mentorship, we analyzed characteristics of abstracts selected for oral and poster discussion presentations at the American Society for Radiation Oncology annual meeting and subsequent high-impact publications.

Methods and Materials

Clinical radiation oncology abstracts selected for oral and poster discussion presentations at the American Society for Radiation Oncology annual meetings in 2014 and 2015 were reviewed. A multivariable logistic regression model evaluated factors associated with subsequent higher-impact publications among abstracts that led to manuscript publications. The primary independent variable was the presenting–senior (last) author gender dyad (divided into 4 groups based on gender of presenting and senior authors, respectively; eg, “MF” indicates male presenting and female senior). Dyads were classified as MF, FM, MM, or FF.

Results

Data were derived from 390 oral and 142 poster discussions. Presenting and senior author pairings were MM for 286 (53.8%), FF for 67 (12.6%), MF for 84 (15.8%), and FM for 94 (17.7%) abstracts. Overall, 403 abstracts led to subsequent publications, of which 52.1% (210) were in a higher-impact journal. Eventual publication in a higher-impact journal was significantly associated with senior author H-index (odds ratio [OR] 3.30 for H ≥ 41 vs < 17; group P = .007), grant support for the study (OR 2.09 for funded vs not, P = .0261), and with the presenting and senior author gender pairing (group P = .0107). Specifically, FM pairings (OR 2.48; 95% confidence interval, 1.32-4.66) and MF pairings (OR 2.38; 95% confidence interval, 1.19-4.77) had higher odds of high-impact publication than MM pairings, whereas there was no significant difference in this outcome between FF and MM pairings.

Conclusions

Although unmeasured confounding remains possible, MF and FM dyads of presenting and senior authors were more likely than MM dyads to obtain journal publication in a higher-impact journal. Institutions and the profession should support the development and maintenance of respectful, collaborative cross-gender mentorship.

The role of facility variation on racial disparities in use of hypofractionated whole breast radiotherapy

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Background: Concerns about racial disparities in the adoption of medical advances motivate investigation of the use of hypofractionated radiotherapy, a less burdensome and less costly approach that is efficacious for most patients with early-stage breast cancer. Methods: A prospectively collected statewide quality consortium database from 25 institutions was queried for breast cancer patients who completed hypofractionated (HF) or conventionally fractionated whole breast radiotherapy (RT) from 1/2012-12/2018. We used patient-level multivariable modeling to evaluate associations between HF use and race, controlling for patient and facility factors, and multilevel modeling to account for patient clustering within facilities. Results: Of 10,318 patients analyzed, 80% self-reported their race as White, 18% as Black, and 2% as Asian, similar to statewide and national distributions. 31% of Whites were treated at academic centers compared to 65% of Blacks and 65% of Asians. In 2018, HF was utilized in 75% of Whites versus 60% of Blacks and 68% of Asians. On patient-level multivariable analysis (see Table), Black and Asian race were significantly associated with a lower likelihood of HF receipt, despite accounting for treatment year, age, laterality, BMI, breast volume, comorbidities, stage, triple-negative status, IMRT use, academic center treatment, and 2011 ASTRO Hypofractionation Guideline eligibility. On multilevel analysis, race was no longer significantly associated with HF receipt. Conclusions: We observed thatBlack and Asian patients receive hypofractionated RT less often, despite more frequent treatment at academic centers. Multilevel modeling eliminated this disparity, suggesting that differences in facility-specific HF use may contribute. Further inquiry is needed to determine if reduction of facility-level variation may reduce disparities in accessing HF treatment.[Table: see text]

Cardiac Dose in Locally Advanced Lung Cancer: Results From a Statewide Consortium

PURPOSE

The heart has been identified as a potential significant organ at risk in patients with locally advanced non-small cell lung cancer treated with radiation. Practice patterns and radiation dose delivered to the heart in routine practice in academic and community settings are unknown.

METHODS AND MATERIALS

Between 2012 and 2017, 746 patients with stage III non-small cell lung cancer were treated with radiation within the statewide Michigan Radiation Oncology Quality Consortium (MROQC). Cardiac radiation dose was characterized, including mean and those exceeding historical or recently proposed Radiation Therapy Oncology Group and NRG Oncology constraints. Sites were surveyed to determine dose constraints used in practice. Patient-, anatomic-, and treatment-related associations with cardiac dose were analyzed using multivariable regression analysis and inverse probability weighting.

RESULTS

Thirty-eight percent of patients had a left-sided primary, and 80% had N2 or N3 disease. Median prescription was 60 Gy (interquartile range, 60-66 Gy). Twenty-two percent of patients were prescribed 60 Gy in 2012, which increased to 62% by 2017 (P < .001). Median mean heart dose was 12 Gy (interquartile range, 5-19 Gy). The volume receiving 30 Gy (V30 Gy) exceeded 50% in 5% of patients, and V40 Gy was >35% in 3% of cases. No heart dose constraint was uniformly applied. Intensity modulated radiation therapy (IMRT) usage increased from 33% in 2012 to 86% in 2017 (P < .001) and was significantly associated with more complex cases (larger planning target volume, higher stage, and preexisting cardiac disease). In multivariable regression analysis, IMRT was associated with a lower percent of the heart receiving V30 Gy (absolute reduction = 3.0%; 95% confidence interval, 0.5%-5.4%) and V50 Gy (absolute reduction = 3.6%; 95% confidence interval, 2.4%-4.8%) but not mean dose. In inverse probability weighting analysis, IMRT was associated with 29% to 48% relative reduction in percent of the heart receiving V40-V60 Gy without increasing lung or esophageal dose or compromising planning target volume coverage.

CONCLUSIONS

Within MROQC, historical cardiac constraints were met in most cases, yet 1 in 4 patients received a mean heart dose exceeding 20 Gy. Future work is required to standardize heart dose constraints and to develop treatment approaches that allow for constraints to be met without compromising other planning goals.

NCTN Assessment on Current Applications of Radiomics in Oncology

Radiomics is a fast-growing research area based on converting standard-of-care imaging into quantitative minable data and building subsequent predictive models to personalize treatment. Radiomics has been proposed as a study objective in clinical trial concepts and a potential biomarker for stratifying patients across interventional treatment arms. In recognizing the growing importance of radiomics in oncology, a group of medical physicists and clinicians from NRG Oncology reviewed the current status of the field and identified critical issues, providing a general assessment and early recommendations for incorporation in oncology studies.

Preventing Harm From Fluoroscopically Guided Interventional Procedures With a Risk-Based Analysis Approach

PURPOSE

Fluoroscopically guided interventional (FGI) procedures often have lower complication rates compared with alternative surgical procedures, providing an option for patients with a high risk of perioperative mortality. Although severe radiation injuries are rare, patients receiving peak skin doses exceeding 3 Gy can suffer from radiation-induced tissue injuries, ranging from transient erythema to nonhealing wounds. As these iatrogenic injuries may manifest weeks to months postprocedure, proper diagnosis and timely medical intervention are less likely. Clinically, the lack of situational awareness for monitoring air kerma continues to be a challenge despite the recommendations of numerous organizations on ways to achieve fluoroscopy safety. For patient safety efforts, this study aimed to identify and mitigate systematic gaps associated with potentially high-radiation dose fluoroscopic procedures in US Department of Veterans Affairs (VA) and non-VA medical institutions.

METHODS

In this study, a multi-institutional team utilized Healthcare Failure Mode and Effect Analysis (HFMEA) on an example implantable cardioverter defibrillator lead extraction procedure.

RESULTS

With this approach, 29 interventions were devised and prioritized by feasibility, cost-effectiveness, and expected clinical impact. Five of the 29 interventions were recommended for immediate implementation or piloting.

CONCLUSIONS

This work demonstrates the application of formal risk-based analysis techniques in FGI procedures. These high priority interventions may be valuable for other facilities to consider when performing potentially high-radiation dose procedures and conducting risk-benefit analyses. Formal risk analysis techniques such as the HFMEA process are recommended for other facilities to use to improve safety for their high-risk procedures.