without violating couch extension limit. Heterogeneity corrections were applied to both TMAT (calculation grid size 0.5 cm) and HT (calculation grid size 0.508 cm) dose calculations. TMAT plans were compared with conventional TBI and HT TMLI plans. TMAT plans were delivered in developer mode via custom XML scripts. Results: The OARs doses in TMAT TMLI were greatly reduced by 30%-50% compared with those for TBI. The percentage decreases in D 50 for lungs, kidney, heart and liver were 36.1%, 42.6%, 45.8% and 38.5%, respectively. The TMAT and HT plans had comparable target coverage and OAR D 80 , D 50 and D 10 (Table1). The average lung D 80 , D 50 and D 10 were 4.5AE0.2 Gy, 5.8AE0.3 Gy and 9.2AE0.6 Gy respectively in TMAT compared to 4.9AE0.5 Gy, 5.8AE0.3 Gy and 9.0AE0.7 Gy with HT. The average kidney D 80 , D 50 and D 10 were 4.7AE0.1 Gy, 5.9AE0.2 Gy and 9.9AE0.8 Gy respectively using TMAT compared with 6.3AE0.2 Gy, 6.6AE0.5 Gy and 10.2AE0.5 Gy using HT. A representative TMAT TMLI plan was implemented in developer mode via XML script. TMAT reduced the treatment time from 20.4 mins to 10.8 mins and monitor unit from 17811 to 4869, but TMAT delivered a less homogenous target dose than HT. Patient specific QA showed all dose points passed the Gamma criterion for a 3%/3-mm threshold. Conclusion: TMAT offered improved mechanical flexibilities to tailor TMLI treatment as an alternative to TBI and HT TMLI. TMAT compared favorably with TBI in terms of OARs dose reduction and with HT in terms of delivery efficiency.
Erectile dysfunction is a significant long-term toxicity of prostatic radiation. Our institution has previously reported on the dosimetric feasibility of MRI-guided neurovascular bundle (NVB) sparing during definitive prostate radiotherapy (RT), a structure that is spared during prostatectomy but not traditionally spared during RT. The purpose of this study is to determine the reproducibility and reliability of contouring the NVB on MRI. Materials/Methods: One hundred twenty total data points on ten consecutive 3-Tesla pelvic MRI's for patients with prostate cancer without extra prostatic extension were reviewed. One pelvic radiologist, with 15 years' experience, served as the expert in contouring the right and left NVB on T2-320 sequences for twenty total structures. Five radiation oncologists, with varying levels of experience, delineated the right and left NVB on the same scans for one hundred total structures. The intraclass correlation coefficient (ICC), Pearson's correlation coefficient (PCC), and the Dice similarity coefficient (DSC) were calculated to evaluate the reproducibility of the MRI-based NVB contours. Results: The overall ICC was 0.89 (95% CI: 0.81-0.95, P<0.01). The PCC for each rater versus the expert were estimated (see Table 1). The average DSC was reported for each rater: rater 1 was 0.72 (standard deviation [SD]: 0.07), rater 2 was 0.73 (SD: 0.06), rater 3 was 0.73 (SD: 0.09), rater 4 was 0.74 (SD: 0.09), and rater 5 was 0.68 (SD: 0.13). Overall across all raters, the average DSC was 0.72 (SD: 0.09). Conclusion: Our series is the first to quantify the reliability and reproducibility of NVB contouring on MRI, with overall excellent agreement among radiation oncologists and the expert radiologist. Additionally, the observed high DSC indicates good overlap of the NVB volumes. Given these results, as well as our institution's previous publication showing the dosimetric feasibility of sparing the NVB during RT, we have begun investigation into a prospective trial evaluation NVB-sparing RT for prostate cancer.
Background we recently reported the involvement of AMPA receptor subunit upregulation and phosphorylation in the rostral cingulate cortex (rCC) as the underlying mechanism of acute esophageal acid-induced cortical sensitization. Based on these findings we proposed to investigate whether prolonged esophageal acid exposures in rats exhibit homeostatic synaptic scaling through downregulation of AMPA receptor expression in rCC neurons. We intended to study further whether this compensatory mechanism is impaired when rats are preexposed to repeated esophageal acid exposures neonatally during neuronal development. Methods two different esophageal acid exposure protocols in rats were used. Since AMPA receptor trafficking and channel conductance depend on CaMKIIα-mediated phosphorylation of AMPA receptor subunits, we examined the effect of esophageal acid on CaMKIIα activation and AMPA receptor expression in synaptoneurosomes (SYNs) and membrane preparations from rCCs. Key Results in cortical membrane preparations, GluA1 and pGluA1Ser831 expression were significantly downregulated following prolonged acid exposures in adult rats, this was accompanied by a significant downregulation of cortical membrane pCaMKIIα expression. No change in GluA1 and pGluA1Ser831 expression was observed in rCC membrane preparations in rats preexposed to acid neonatally followed by adult rechallenge. Conclusions & Inferences this study along with our previous findings suggests that synaptic AMPA receptor subunits expression and phosphorylation may be involved bidirectionally in both esophageal acid-induced neuronal sensitization as well as acid-dependent homeostatic plasticity in cortical neurons. The impairment of homeostatic compensatory mechanism as observed following early-in-life acid exposure could be the underlying mechanism of heightening cortical sensitization and esophageal hypersensitivity in patients with GERD.
bag V40 Gy reductions up to 25%. The largest reductions were seen with the online 3 mm PTV margin strategy where rectal and bladder V40 Gy was reduced by 48% and 53% respectively. Plan selection resulted in 20% and 25% reduction in rectal and bladder V40 Gy. Conclusion: ART solutions for cervix EBRT reduce PTV volumes and OAR doses. Daily online re-planning delivers the largest OAR dose reductions. A clinical study combining MRI-guided RT and daily online replanning will assess clinical benefit in implementing these ART strategies.
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