Slowing of progression and inducing the regression of atherosclerosis with medical therapy have been shown to be associated with an extensive reduction in risk of cardiovascular events. This proof of concept was obtained with invasive angiographic studies but these are, for obvious reasons, impractical for sequential investigations. Non-invasive imaging has henceforth replaced the more cumbersome invasive studies and has proven extremely valuable in numerous occasions. Because of excellent reproducibility and no radiation exposure, magnetic resonance imaging (MRI) has become the non-invasive method of choice to assess the efficacy of anti-atherosclerotic drugs. The high accuracy of this technology is particularly helpful in rare diseases where the small number of affected patients makes the conduct of outcome-trials in large cohorts impractical. With MRI it is possible to assess the extent, as well as the composition, of atherosclerotic plaques and this further enhances the utility of this technology.
Angeles (UCLA). Materials/Methods: 43 patients diagnosed with AM treated with RT at UCLA from 1999-2015 were identified and retrospectively analyzed. We noted that the definition of grade II AM changed in 2007. Patients were selected based on the grading system during the year they were diagnosed. Data on age, race, gender, surgical type, radiation dose and modality were investigated. Estimates of relapse-free survival (RFS) and overall survival (OS) were performed using the Kaplan-Meier method. Results: 30 patients received adjuvant radiation therapy (ART) after surgery at the initial diagnosis. Of those, 14 had gross total resection (GTR), 16 had subtotal resection (STR). 13 received salvage radiation therapy (SaRT) for recurrent AM following previous surgery. Of those, 9 received GTR at initial diagnosis, 4 underwent STR. The median age at diagnosis was 59, range 38-79. There were 31 Caucasian, 7 Asian, 3 African American, and 2 Hispanic. There were 21 females and 22 males. The median follow up was 32.5 months, range 1.5-108. In the ART group, 1 patient received stereotactic radiosurgery (SRS) and 29 patients received fractionated external beam radiotherapy (EBRT). The median dose was 55.8 Gy (range 48.6-59.4). The single SRS dose was 12 Gy, which is noted to be unusually low for SRS to AM. In the SaRT group, 4 patients received SRS and 9 patients received fractionated EBRT. The median dose was 54 Gy (range 50.4-60); the median SRS dose was 14 Gy (range 14-16). In the ART group, the RFS at 3 and 5 year was 90% and 78%, respectively; the OS at 3 and 5 year was 95%. In the SaRT group, the RFS at 3 and 5 year was 62.5%; the OS at 3 and 5 year was 100%. Compared to historic controls reporting ART for AM, the RFS and OS at 5 years range from 50-92% and 67-84%, respectively. We performed an analysis using the Surveillance, Epidemiology, and End Results Program (SEER) database evaluating patients with grade II AM who underwent GTR without ART between 2004-2010. The 3 and 5 year OS were 89% and 84%, respectively. Conclusion: ART for AM at our institution provides similar RFS and OS compared to historical controls published in the literature. With further data collection, we plan to evaluate the outcomes of these patients based on surgical resection, STR vs GTR, to determine the role of ART in AM. Patients from the SEER database with GTR had high 3 and 5 year OS. SaRT for resected AM that recurred also provided excellent OS, although RFS was not as high in the adjuvant setting. The role of ART in AM after GTR remains controversial. However, there appears to be a benefit to ART vs SaRT for local control and further studies are necessary to evaluate this potential benefit.
Purpose: Large setup variability has been observed for prone breast patients due to rotation error. To reduce this uncertainty, we propose a novel implementation of isocentric prone breast method on Elekta linac with couch move assistant (CMA) and on‐line KV CBCT. Methods: Daily CBCT is used to evaluate the prone breast patient positioning uncertainty of proposed isocentric technique against our routine manual clinical setup. Clinical setup involves a manual AP shift from the ipsilateral torso tattoos (2PT) to the treatment iso directly underneath and SSD and flash check. While the proposed isocentric prone breast method features an additional contralateral leveling tattoo positioned at mid‐level of torso during CT simulation to determine correct patient obliqueness, and an automatic couch shift using Elekta CMA to correct both known distance from 2PT to the iso and daily setup uncertainty. Summary statistics were calculated for a cohort of prone breast patients from our clinic (n=5), and will be updated as more patients get administrated. Results: Small field of view partial CBCT acquisition is optimized to achieve clearance and minimize nominal imaging dose to 0.6cGy per scan to a 16cm phantom. Routine clinical setup uncertainty is 0.3±0.2cm, 0.7±0.4cm and 0.4±0.3cm in S/I, L/R and A/P respectively. Using the isocentric prone breast method, the setup uncertainty could be reduced to 0±0.3cm, 0.3±0.4cm and 0.1±0.3cm if the average couch shift in the 1st week of treatment is applied by CMA to the rest of treatment days. The uncertainty could be further reduced to 0.3±0.1cm, 0±0.1cm and 0±0.2cm with additional contralateral leveling tattoo. The improvement in precision is found to be statistically significant (p<0.05) using unpaired student t‐tests. Conclusion: Contralateral leveling tattoo is essential to determine correct patient obliqueness. More consistent and accurate isocentric prone breast patient positioning is achievable on Elekta linac with CMA and CBCT.
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