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PURPOSE/OBJECTIVE(S) To survey the utilization, interest in, and barriers to implementation of radiopharmaceuticals/unsealed sources amongst U.S. radiation oncologists. MATERIALS/METHODS An anonymous, voluntary survey directed towards attending radiation oncologists was distributed via social media platforms (Twitter, LinkedIn, SDN, Facebook). Questions assessed practice characteristics, radiopharmaceutical prescribing patterns (Iodine-131, Radium-223, Yttrium-90, Sumarium-153, Strontium-89, Phosphorous-32, "other"), prescribing interest level, and perceived barriers to implementation. Non-parametric χ2 test was used for correlation statistics. RESULTS Of the 120 respondents, 112 practiced in the U.S and were included for this analysis. Years of practice was broadly distributed with 30% (n = 34) of attendings in practice > 10 years, 21% (n = 23) 6-10 years, 25% (n = 28) 3-5 years, and 24% (n = 27) 0-2 years. Practice type included academic-main site amongst 39% (n = 44), academic-satellite in 18% (n = 20), and private practice/other in 43% (n = 48) of attendings. Forty-four percent (n = 49) of attendings served populations of > 500K, 22% (n = 25) 200-500K, 25% (n = 28) 100-200K, and 9% (n = 10) 0.05) association was noted between practice type, practice location, years of practice, or practice volume with utilization of any radiopharmaceuticals/unsealed sources. The majority (55%, n = 61) of attending radiation oncologists responded they would like to actively prescribe more radiopharmaceuticals/unsealed sources, while 30% (n = 31) were indifferent and 18% (n = 20) answered "no." Perceived barriers to implementation were varied but broadly categorized into treatment infrastructure (43%, n = 48), interspecialty relations (42%, n = 47), lack of training (21%, n = 24), and financial considerations (17%, n = 19). CONCLUSION Almost half of surveyed U.S. radiation oncologists reported prescribing at least one radiopharmaceuticals/unsealed source, of which Ra-223 was the most common. The majority expressed interest in prescribing additional radiopharmaceuticals/unsealed sources. Wide-ranging barriers to implementation exist, most commonly interspecialty relations, treatment infrastructure, lack of training, and financial considerations.

This study reports dose corresponding to visible radiation induced liver damage following Stereotactic Body Radiation Therapy (SBRT) for liver metastasis, and the optimal time for follow up scans using post radiation imaging. Diagnostic magnetic resonance scans of nine patients treated with liver SBRT using a 0.35 T MRI-guided radiotherapy system were analyzed. The dice coefficients between the region of visible liver damage and the delivered dose were calculated. A median dose of 35 Gy correlated most closely with the visible radiation induced liver damage. We compared scans over two to nine months and observed maximal dice coefficients at two to five months post radiation. We have presented a new method for developing treatment planning guidelines for liver SBRT.

Purpose The role of neoadjuvant radiation for resectable pancreatic adenocarcinoma is controversial. We performed a prospective dose-escalation study of neoadjuvant stereotactic body radiation therapy (SBRT) with concurrent capecitabine and elective nodal irradiation (ENI) followed by surgical resection to explore the toxicity and feasibility of this approach. Methods and Materials Patients with biopsy proven, resectable cancers of the pancreatic head were enrolled. A 4 + 4 dose-escalation design was employed delivering 5 fractions of 5 to 7 Gy to primary tumor with concurrent capecitabine. The maximum tolerated dose level was expanded for an additional 4 patients. Patients at all dose levels were treated with ENI delivering 25 Gy in 5 fractions. Dose-limiting toxicity was defined as any grade ≥3 nonhematologic toxicity (National Cancer Institute Common Terminology Criteria for Adverse Events v4.0) attributable to chemoradiation occurring within 90 days of SBRT. Results A total of 17 patients were enrolled with 16 patients evaluable and 13 patients ultimately proceeding to surgery. The most common toxicity was nausea (56%). There were no dose-limiting toxicities, and SBRT was maximally dose escalated to 35 Gy in 5 fractions for 8 patients. All patients completing surgery had R0 resections. Seven patients (54%) had moderate treatment effect identified in pathologic specimens. Three patients (23%) developed locoregional recurrences, with 2 (15%) partially included within the treated volume. Conclusions SBRT was safely dose escalated to 35 Gy in 5 fractions along with concurrent capecitabine and ENI. This regimen will be used in a future expansion cohort.