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Uniform Dose (uniform + dose)
Selected AbstractsSuboccipital Nerve Blocks for Suppression of Chronic Migraine: Safety, Efficacy, and Predictors of OutcomeHEADACHE, Issue 6 2010Silvia Weibelt RN (Headache 2010;50:1041-1044) Background., Approximately 1 in 50 Americans is afflicted by chronic migraine (CM). Many patients with CM describe cervicogenic headache. Options for treating CM effectively are at present quite limited. Objective., To determine the safety and efficacy of occipital nerve blocks (ONBs) used to treat cervicogenic chronic migraine (CCM) and to identify variables predictive of a positive treatment response. Methods., Using a uniform dose and injection paradigm, we performed ONBs consecutively on a series of patients presenting with CCM. Patients were stratified according to specific findings found to be present or absent on physical examination. A positive treatment outcome was defined as a 50% or greater reduction in headache days per month over the 30 days following treatment relative to the 30-day pre-treatment baseline. We used a 5-point Likert scale as one of the secondary outcome variables. Results., We treated 150 consecutive patients with unilateral (37) or bilateral (113) ONBs. At the 1-month follow-up visit 78 (52%) exhibited evidence of a positive treatment response according to the primary outcome variable, and 90 (60%) reported their headache disorder to be "better" (44; 29%) or "much better" (46; 30%). A total of 8 (5%) patients reported adverse events within the ensuing 72 hours, and 3 (2%) experienced adverse events that reversed spontaneously but required emergent evaluation and management. Conclusion., For suppression of CCM, ONBs may offer an attractive alternative to orally administered prophylactic therapy. [source] ORIGINAL ARTICLE: Sparing of the hippocampus and limbic circuit during whole brain radiation therapy: A dosimetric study using helical tomotherapyJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 4 2010JC Marsh Abstract Introduction:, The study aims to assess the feasibility of dosimetrically sparing the limbic circuit during whole brain radiation therapy (WBRT) and prophylactic cranial irradiation (PCI). Methods and Materials:, We contoured the brain/brainstem on fused MRI and CT as the target volume (PTV) in 11 patients, excluding the hippocampus and the rest of the limbic circuit, which were considered organs at risk (OARs). PCI and WBRT helical tomotherapy plans were prepared for each patient with a 1.0-cm field width, pitch = 0.285, initial modulation factor = 2.5. We attempted to spare the hippocampus and the rest of the limbic circuit while treating the rest of the brain to 30 Gy in 15 fractions (PCI) or 35 Gy in 14 fractions (WBRT) with V100 , 95%. The quality of the plans was assessed by calculating mean dose and equivalent uniform dose (EUD) for OARs and the % volume of the PTV receiving the prescribed dose, V100. Results:, In the PCI plans, mean doses/EUD were: hippocampus 12.5 Gy/14.23 Gy, rest of limbic circuit 17.0 Gy/19.02 Gy. In the WBRT plans, mean doses/EUD were: hippocampus 14.3 Gy/16.07 Gy, rest of limbic circuit 17.9 Gy/20.74 Gy. The mean V100 for the rest of the brain (PTV) were 94.7% (PCI) and 95.1% (WBRT). Mean PCI and WBRT treatment times were essentially identical (mean 15.23 min, range 14.27,17.5). Conclusions:, It is dosimetrically feasible to spare the hippocampus and the rest of the limbic circuit using helical tomotherapy while treating the rest of the brain to full dose. [source] Accrediting radiation technique in a multicentre trial of chemoradiation for pancreatic cancerJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 6 2008N Spry Summary Before a multicentre trial of 3-D conformal radiotherapy to treat cancer of the pancreas, participating clinicians were asked to complete an accreditation exercise. This involved planning two test cases according to the study protocol, then returning hard copies of the plans and dosimetric data for review. Any radiation technique that achieved the specified constraints was allowed. Eighteen treatment plans were assessed. Seven plans were prescribed incorrect doses and two of the planning target volumes did not comply with protocol guidelines. All plans met predefined normal tissue dose constraints. The identified errors were attributable to unforeseen ambiguities in protocol documentation. They were addressed by feedback and corresponding amendments to protocol documentation. Summary radiobiological measures including total weighted normal tissue equivalent uniform dose varied significantly between centres. This accreditation exercise successfully identified significant potential sources of protocol violations, which were then easily corrected. We believe that this process should be applied to all clinical trials involving radiotherapy. Due to the limitations of data analysis with hard-copy information only, it is recommended that complete planning datasets from treatment-planning systems be collected through a digital submission process. [source] Comparison of non-coplanar and coplanar irradiation techniques to treat cancer of the pancreasJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 5 2006C Osborne Summary We compared two different techniques of pancreatic irradiation using measures associated with normal tissue complications. Seven consecutive patients with pancreatic cancer were planned for both coplanar and non-coplanar (NCP) external beam radiation treatments, using the same defined anatomical volumes for each patient, in each case. Each pair of plans was then compared using a range of objective criteria. Individual normal tissues were assessed against traditional tolerance limits. Selected dose-points, normal tissue complication probability (NTCP) and equivalent uniform doses (EUD) were also compared, as were indices combining information from individual tissues , total NTCP and total weighted EUD. All individual normal tissues doses were within established tolerance limits. For NCP relative to coplanar planning, NTCP and EUD were lower for all individual tissues in four cases and one case, respectively, i.e. in most cases a benefit to one tissue was offset by detriment to others. Summary measures demonstrated overall benefits for NCP techniques, with the total NTCP in six patients, and with the total weighted EUD in all patients. NCP techniques show potentially useful benefits. We present a new objective measure, the total weighted EUD, which may be particularly useful comparing plans where there are multiple critical tissues. [source] | ||||||||||