Brandon A. Dyer

Radiation-Induced Morphea: An Under-Recognized Complication of Breast Irradiation

Radiation-induced morphea (RIM) is a rare painful and disfiguring radiation complication in women who receive adjuvant treatment after breast-conserving surgery. It is a distinct entity unrelated to radiationinduced fibrosis of the breast with an estimated prevalence of 1 to 2 per 1000 treated. There is little mention of this entity in the radiation oncology literature; however, it has been previously described in dermatology and pathology literature. Temporal course and expected clinical findings of RIM are discussed. A cytopathologic compare and contrast between RIM and radiation induced fibrosis is provided. Clinical pictures are included to aid with provider recognition and treatment options are reviewed. Unfortunately, there are no known predictors for RIM, nor proven treatment options. Early provider recognition enables patient reassurance that symptoms will improve and can help outline potential treatment options. However, patients who develop RIM are considered a failure to breast conservation, because they continue to have a poor cosmetic long-term outcome. RIM is considered a failure to breast conservation therapy. Early provider recognition is paramount to patient mental and physical well-being.

Surveillance imaging following definitive radiotherapy for non–small cell lung cancer: What is the clinical impact?

Lung cancer is the leading cause of cancer death worldwide. Recurrence rates at all stages are high, but evidence-based post-treatment surveillance imaging strategies to detect recurrence are poorly defined, and salvage options are frequently limited. A number of national and international oncology guidelines address post-treatment imaging, but are largely based on low-level, retrospective evidence because of a paucity of high-quality data, particularly in regard to cost-effectiveness and quality-of-life endpoints. Given the lack of randomized data addressing appropriate surveillance imaging modality and interval following definitive treatment of lung cancer, there remains an unmet clinical need. Meaningful surveillance endpoints should include the financial impact, patient quality-of-life outcomes, and access-to-care issues associated with intensive follow-up to ensure that guidelines reflect quality and sustainability. A need for prospective randomized data on the subject of imaging surveillance after definitive local therapy remains an unmet need, and an opportunity for collaboration and further research.

Fabrication of an anthropomorphic heterogeneous mouse phantom for multimodality medical imaging

This work presents a comprehensive methodology for constructing a tissue equivalent mouse phantom using image modeling and 3D printing technology. The phantom can be used in multimodality imaging and irradiation experiments, quality control, and management. Computed tomography (CT) images of a mouse were acquired and imported into 3D modeling software. A skeleton and skin shell models were segmented in the modeling software and manufactured using 3D printing technology. The bone model was constructed with VERO-WHITE printing material with additional ingredients, including a photosensitive resin, polyurethane epoxy resin, and acrylate. Acrylonitrile butadiene styrene resin material was used to construct the skin shell. The skin shell was attached to the skeleton and filled with a specially formulated gel to act as a soft tissue substitute. The gel consisted of agarose, micro-pearl powder, sodium chloride, and magnevist solution (gadopentetate dimeglumine). A micro-container filled with 18F-fluorodeoxyglucose (18F-FDG) radioactive tracer was placed in the abdomen for micro and human positron emission tomography (PET)/CT imaging. The mouse phantom had tissue equivalency in dose attenuation with x-rays and relaxation times with magnetic resonance imaging (MRI). The CT Hounsfield Unit (HU) range for the gel soft tissue material was 31-36 HU. The 3D printed bone mimetic material had equivalent tissue/bone contrast compared with in vivo mouse measurements with a mean value of 130  ±  10 HU. At different magnetic field strengths, the T 1 relaxation time of the soft tissue was 382.75-506.48 ms, and T 2 was 51.11-70.76 ms. 18F-FDG tracer could be clearly observed in PET imaging. The 3D printed mouse phantom was successfully constructed with tissue-equivalent materials. Our model can be used for CT, MRI, and PET as a standard device for small-animal imaging and quality control.

Integrated skin flash planning technique for intensity-modulated radiation therapy for vulvar cancer prevents marginal misses and improves superficial dose coverage

INTRODUCTION Radiation therapy (RT) plays a definitive role in locally advanced vulvar cancer, and in the adjuvant setting with high risk postoperative features after wide local excision. There is significant morbidity associated with traditional, large RT fields using 2D or 3D techniques, and the use of intensity-modulated radiation therapy (IMRT) in vulvar cancer is increasing. However, there remains a paucity of technical information regarding the prevention of a marginal miss during the treatment planning process. The use of an integrated skin flash (ISF) during RT planning can be used to account for anatomic variation, and intra- and interfraction motion seen during treatment. CASE DESCRIPTION Herein we present the case of a patient with a T1aN0M0, Stage IA vulva cancer to illustrate the progressive vulvar swelling and lymph edema seen during treatment and retrospectively evaluate the dosimetric effects of using an ISF RT plan vs standard RT planning techniques. CONCLUSIONS Standard planning techniques to treat vulvar cancer patients with IMRT do not sufficiently account for the change in patient anatomy and can lead to a marginal miss. ISF is an RT planning technique that can decrease the risk of a marginal miss and the technique is easily implemented during the planning stages of RT treatment. Furthermore, use of an ISF technique can improve vulvar clinical target volume coverage and plan homogeneity. Based on our experience, and this study, a 2-cm ISF is suggested to account for variations in daily clinical setup and changes in patient anatomy during treatment.

A prospective in silico analysis of interdisciplinary and interobserver spatial variability in post-operative target delineation of high-risk oral cavity cancers: Does physician specialty matter?

Background The aim of this study was to determine the interdisciplinary agreement in identifying the post-operative tumor bed. Methods Three radiation oncologists (ROs), four surgeons, and three radiologists segmented post-operative tumor and nodal beds for three patients with oral cavity cancer. Specialty cohort composite contours were created by STAPLE algorithm implementation results for interspecialty comparison. Dice similarity coefficient and Hausdorff distance were utilized to compare spatial differentials between specialties. Results There were significant differences between disciplines in target delineation. There was unacceptable variation in Dice similarity coefficient for each observer and discipline when compared to the STAPLE contours. Within surgery and radiology disciplines, there was good consistency in volumes. ROs and radiologists have similar Dice similarity coefficient scores compared to surgeons. Conclusion There were significant interdisciplinary differences in perceptions of tissue-at-risk. Better communication and explicit description of at-risk areas between disciplines is required to ensure high-risk areas are adequately targeted.

Anesthesia and Procedural Care for Brachytherapy

The cornerstone to providing safe, effective anesthesia during brachytherapy is a thorough pre-procedural evaluation. An individualized anesthesia plan should be developed well in advance of any foreseen procedure to mitigate patient risk and allow ample time for changes in the anesthetic plan. In general, the indications and risks to patients receiving anesthesia for brachytherapy are similar to other procedures and established pre- and post-procedural instructions should be given, and explained to all patients. In patients deemed at high risk for thrombosis (e.g., certain cardiac dysrhythmias, prosthetic heart valve, history of deep vein thrombosis or prior thromboembolism) warfarin should be bridged with enoxaparin or low molecular weight heparin to minimize peri-procedural risk of bleeding. Premedication may be given to the patient for anxiolytics or post-procedural nausea and vomiting prophylaxis. Site-specific brachytherapy discharge instructions should be provided and red-flag symptoms should be reviewed with the patient prior to procedural discharge.

Durable Local Control Following Concurrent Hypofractionated Chemoradiation for a Massive Inflammatory Breast Cancer Chest Wall Recurrence

Breast cancer is the leading new cancer diagnosis in women in the United States and is the second most lethal cancer in this patient population after lung cancer. Chest wall recurrence after mastectomy poses unique clinical challenges, as such tumors are often not amenable to surgical resection and durable local control with radiation or systemic therapy is challenging. When uncontrolled, chest wall recurrence can lead to severe pain and other morbidity. Herein, we describe a patient with inflammatory breast cancer with a massive, rapidly growing chest wall recurrence treated with a regimen of hypofractionated concurrent chemoradiation resulting in a complete chest wall response with durable local control.

SU-F-T-471: Simulated External Beam Delivery Errors Detection with a Large Area Ion Chamber Transmission Detector

PURPOSE The Integral Quality Monitor (IQM), developed by iRT Systems GmbH (Koblenz, Germany) is a large-area, linac-mounted ion chamber used to monitor photon fluence during patient treatment. Our previous work evaluated the change of the ion chambers response to deviations from static 1×1 cm2 and 10×10 cm2 photon beams and other characteristics integral to use in external beam detection. The aim of this work is to simulate two external beam radiation delivery errors, quantify the detection of simulated errors and evaluate the reduction in patient harm resulting from detection. METHODS Two well documented radiation oncology delivery errors were selected for simulation. The first error was recreated by modifying a wedged whole breast treatment, removing the physical wedge and calculating the planned dose with Pinnacle TPS (Philips Radiation Oncology Systems, Fitchburg, WI). The second error was recreated by modifying a static-gantry IMRT pharyngeal tonsil plan to be delivered in 3 unmodulated fractions. A radiation oncologist evaluated the dose for simulated errors and predicted morbidity and mortality commiserate with the original reported toxicity, indicating that reported errors were approximately simulated. The ion chamber signal of unmodified treatments was compared to the simulated error signal and evaluated in Pinnacle TPS again with radiation oncologist prediction of simulated patient harm. RESULTS Previous work established that transmission detector system measurements are stable within 0.5% standard deviation (SD). Errors causing signal change greater than 20 SD (10%) were considered detected. The whole breast and pharyngeal tonsil IMRT simulated error increased signal by 215% and 969%, respectively, indicating error detection after the first fraction and IMRT segment, respectively. CONCLUSION The transmission detector system demonstrated utility in detecting clinically significant errors and reducing patient toxicity/harm in simulated external beam delivery. Future work will evaluate detection of other smaller magnitude delivery errors.