COMPREHENSIVE CALCULATION-BASED IMRT QA USING R&V DATA, TREATMENT RECORDS, AND A SECOND TREATMENT PLANNING SYSTEM

Purpose: Traditional patient-specific IMRT QA measurements are labor intensive and consume machine time. Calculation-based IMRT QA methods typically are not comprehensive. We have developed a comprehensive calculation-based IMRT QA method to detect uncertainties introduced by the initial dose calculation, the data transfer through the Record-and-Verify (R&V) system, and various aspects of the physical delivery. Methods: We recomputed the treatment plans in the patient geometry for 48 cases using data from the R&V, and from the delivery unit to calculate the “as-transferred” and “as-delivered” doses respectively. These data were sent to the original TPS to verify transfer and delivery or to a second TPS to verify the original calculation. For each dataset we examined the dose computed from the R&V record (RV) and from the delivery records (Tx), and the dose computed with a second verification TPS (vTPS). Each verification dose was compared to the clinical dose distribution using 3D gamma analysis and by comparison of mean dose and ROI-specific dose levels to target volumes. Plans were also compared to IMRT QA absolute and relative dose measurements. Results: The average 3D gamma passing percentages using 3%-3mm, 2%-2mm, and 1%-1mm criteria for the RV plan were 100.0 (σ=0.0), 100.0 (σ=0.0), and 100.0 (σ=0.1); for the Tx plan they were 100.0 (σ=0.0), 100.0 (σ=0.0), and 99.0 (σ=1.4); and for the vTPS plan they were 99.3 (σ=0.6), 97.2 (σ=1.5), and 79.0 (σ=8.6). When comparing target volume doses in the RV, Tx, and vTPS plans to the clinical plans, the average ratios of ROI mean doses were 0.999 (σ=0.001), 1.001 (σ=0.002), and 0.990 (σ=0.009) and ROI-specific dose levels were 0.999 (σ=0.001), 1.001 (σ=0.002), and 0.980 (σ=0.043), respectively. Comparing the clinical, RV, TR, and vTPS calculated doses to the IMRT QA measurements for all 48 patients, the average ratios for absolute doses were 0.999 (σ=0.013), 0.998 (σ=0.013), 0.999 σ=0.015), and 0.990 (σ=0.012), respectively, and the average 2D gamma(5%-3mm) passing percentages for relative doses for 9 patients was were 99.36 (σ=0.68), 99.50 (σ=0.49), 99.13 (σ=0.84), and 98.76 (σ=1.66), respectively. Conclusions: Together with mechanical and dosimetric QA, our calculation-based IMRT QA method promises to minimize the need for patient-specific QA measurements by identifying outliers in need of further review.

Comparison of two strategies for the treatment of acute myocardial infarction: In-hospital outcomes analysis

A strategy of pre-hospital reduced dose fibrinolytic administration coupled with urgent coronary intervention (PCI) for patients with STEMI (FAST-PCI) has been found to be superior to primary PCI (PPCI) alone. A coordinated STEMI system-of-care that includes FAST-PCI might offer better outcomes than pre-hospital diagnosis and STEMI team activation followed by PPCI alone. We compared the in-hospital outcomes for patients treated with the FAST-PCI approach with outcomes for patients treated with the PPCI approach during a pause in the FAST-PCI protocol. In-hospital data for 253 STEMI patients (03/2003–12/2009), treated with FAST-PCI protocol were compared to 124 patients (12/2009–08/2011), treated with PPCI strategy alone. In-hospital mortality was the primary endpoint. Stroke, major bleeding, and reinfarction during index hospitalization were secondary endpoints. Comparing the strategies used during the two time intervals, in-hospital mortality was significantly lower with FAST-PCI than with PPCI (2.77% vs. 10.48%, p = 0.0017). Rates of stroke, reinfarction and major bleeding were similar between the two groups. There was a lower frequency of pre- PCI TIMI 0 flow (no patency) seen in patients treated with FAST-PCI compared to the PPCI patients (26.7% vs. 62.7%, p<0.0001). Earlier infarct related artery patency in the FAST-PCI group had a favorable impact on the incidence of cardiogenic shock at hospital admission (FAST-PCI- 3.1% vs. PPCI- 20.9%, p<0.0001). The FAST-PCI strategy was associated with earlier infarct related artery patency and the lower incidence of cardiogenic shock on hospital arrival, as well as with reduced in-hospital mortality among STEMI patients.^