The aim of this study is to describe the HDR-IORT-DP technique and report on the preliminary clinical outcomes of patients treated with this approach. Beginning in 2007, the DP technique was introduced for HDR-IORT cases at Memorial Sloan–Kettering Cancer Center; thus the treatment plans for all patients find more who received IORT after January 2007 were reviewed to identify IORT plans using DP. A total of 207 patients with locally advanced or recurrent neoplasms, who underwent IORT between January 12, 2007 and August 25, 2010 were identified. Among this group, 16 patients (7.7%) received HDR-IORT-DP

and comprised our study group: 13 patients had recurrent colorectal cancer, 2 patients had recurrent cancer of the head and neck region, and 1 had a gynecologic malignancy. All patients in this group had undergone surgical resection and EBRT previously and had areas within the field that were identified by the surgeon to be at higher risk of microscopic residual disease or were adjacent to critical structures such as the ureter, where adequate BIBW2992 shielding could not be achieved owing to geometric constraints. DP was indicated in these cases to either achieve modulation of the dose and delivery

of a concomitant boost to higher-risk areas within the resection bed, while delivering a lower dose to the regions closest to normal structures or to achieve even more conformal dosimetry to a more complicated geometric region within the square or rectangular treatment region created

by the HAM applicator. At the time of HDR-IORT-DP, patients were undergoing radical resection with expected close margins owing to locally advanced/recurrent nature of the tumors. Final resection margins were negative (R0) in 12 patients (75%) and microscopically positive margins (R1) in 4 patients (25%). Patient and treatment characteristics are shown in Table 1. The HDR-IORT-DP was delivered using the HAM applicator, a flexible pad of silicone rubber that has 8-mm thickness and 22 cm in length (Fig. 1). Multiple catheters (3–24) are embedded parallel to each other spaced 10-mm apart, while a fixed source-to-tissue distance of 5 mm is maintained. All procedures were performed in a dedicated shielded operating room. The HDR-IORT-DP technique can be summarized as follows: After Sulfite dehydrogenase tumor resection, the decision to proceed with IORT is based on the radiation oncologist’s and the surgeon’s impression of the risk for close or microscopically positive margins. If deemed necessary, the area at risk is mapped out by the surgeon and radiation oncologist, and the HAM applicator is chosen with the number of channels to cover the target area appropriately. A sterile, transparent, and flexible template that mimics the HAM applicator and varies in number of channels from 3 to 24 is used to define the “DP” regions within the treatment area (Fig. 2).