Online Adaptive Radiation Therapy and Opportunity Cost.

Purpose: Changes in patient anatomy and tumor geometry pose a challenge to ensuring consistent target coverage and organ-at-risk sparing; online adaptive radiation therapy (ART) accounts for these interfractional changes by facilitating replanning before each treatment. This project explored the opportunity cost of computed tomography (CT)-based online ART by evaluating time and human resource requirements. Time-driven activity-based costing (TDABC) was employed to determine the cost of this time to assess if the dosimetric benefit is worthwhile. Methods and Materials: CT-based online ART was recently employed at our institution and has been used to treat pelvic disease sites (prostate, prostate bed, prostate with nodal coverage, bladder, rectum); data points from all adaptively treated patients (415 fractions) were used. Time taken for each adaptive fraction before treatment, which at our facility is best represented by the duration between 2 cone beam CT scans, was used as a broadly applicable and transferable metric, representing the additional time required for ART on top of standard image guided radiation therapy. Dosimetric effect was also considered by taking the difference of planning target volume V100% for the scheduled and adapted plans. Using recently validated TDABC at this facility, the per fraction cost of ART was determined, reflecting the added cost of ART on top of image guided radiation therapy. Results: A median time of 15.97 (interquartile range, 13.23-18.83) additional minutes was required for each adaptive fraction. TDABC demonstrated an average minimum cost per adapted fraction of $103.58. Dosimetric differences between V100% of the scheduled versus adapted plan showed a mean dosimetric difference of 15.8%. Conclusions: Although online ART decreases the uncertainty of anatomic shifts, each adaptive fraction requires more staff time, delaying completion of other tasks and increasing resource utilization. Although toxicity benefits require further studies, the implementation of progressively complex radiation therapy technologies, like ART, requires consideration of the time and human resource requirements and subsequent opportunity cost.

The Use of Low-Dose Radiation Therapy in Osteoarthritis: A Review.

Despite its clinical use and investigation in other countries, low dose radiation therapy (LDRT) in the treatment of osteoarthritis (OA) is minimally used in the United States (US). Numerous recent studies published outside the US have shown moderate to long-term pain relief and improvement of mobility after treatment with LDRT for joints affected by OA. Here, we review the most recent literature published on the use of LDRT in OA. We provide a brief outline on the epidemiology, pathophysiology, current treatments, and health care burden of OA within the US. We provide a brief history of the historic use of LDRT in the US as well as a history of LDRT within the modern era of radiation oncology, discuss criticisms of LDRT including recently published randomized trials questioning its benefit as well as the risk of secondary malignancy from LDRT, and provide an outline of treatment planning considerations and recommendations regarding dose and fractionation, energy, beam arrangements, and immobilization techniques. LDRT has been shown to be a cost-effective, noninvasive treatment with minimal side effects. Further investigation into the potential role in the treatment of OA with modern LDRT is recommended.

Pre- and Posttherapy Risk Factors for Vasculopathy in Pediatric Patients With Craniopharyngioma Treated With Surgery and Proton Radiation Therapy.

PURPOSE: Vasculopathy (VAS) is a significant complication associated with radiation therapy in patients treated for brain tumors. We studied the type, location, severity, timing, and resolution of VAS in children with craniopharyngioma treated with proton radiation therapy (PRT) and evaluated predictors of stenosis (STN) using a novel patient and imaging-based modeling approach. METHODS AND MATERIALS: Children with craniopharyngioma (n = 94) were treated with 54 Gy relative biological effectiveness PRT in a clinical trial, NCT01419067. We evaluated VAS type, location, severity, and resolution. VAS events were segmented and related to their location, operative corridor, PRT dose, and vascular territory to facilitate mixed effect logistic regression modeling of spatial predictors of STN events. RESULTS: Forty-five (47.9%) patients had 111 instances of confirmed VAS (pre-PRT n = 37, 33.3%). The median time to post-PRT VAS was 3.41 years (95% confidence interval, 1.86-6.11). STN events were observed post-PRT in 23.4% (n = 22) of patients. Post-PRT VAS was detected by cerebral angiogram in 9.6% (n = 9), severe in 4.3% (n = 4), and compensated on perfusion in 2.1% (n = 2). Revascularization was required for 5 (5.3%) patients. Postsurgical, pre-PRT VAS, and PRT dose to unperturbed vessels were predictive of STN. The effect of PRT on STN was negligible within the surgical corridor. CONCLUSIONS: VAS often precedes PRT and was the strongest predictor of post-PRT STN. The adverse effect of PRT on STN was only apparent in unperturbed vasculature beyond the operative corridor.

Scalp and Cranium Radiation Therapy Using Modulation (SCRUM) and Bolus.

PURPOSE: A bolus is usually required to ensure radiation dose coverage of extensive superficial tumors of the scalp or skull. Oftentimes, these boluses are challenging to make and are nonreproducible, so an easier method was sought. METHODS AND MATERIALS: Thermoplastic sheets are widely available in radiation oncology clinics and can serve as bolus. Two template cutouts were designed for anterior and posterior halves to encompass the cranium of children and adults. RESULTS: The created bolus was imaged using computed tomography, which demonstrated good conformity and minimal air gaps. CONCLUSIONS: Although making a bolus for treating superficial tumors of the scalp or head and neck is challenging, the presented technique enables thermoplastic to be used as a bolus and is quick, easy, and reproducible.