Evaluation of the deliverability of dynamic conformal arc therapy (DCAT) by gantry wobble and its influence on dose.

We aimed to investigate the deliverability of dynamic conformal arc therapy (DCAT) by gantry wobble owing to the intrinsic inter-segment break of the Elekta linear accelerator (LINAC) and its adverse influence on the dose to the patient. The deliverability of DCAT was evaluated according to the plan parameters, which affect the gantry rotation speed and resultant positional inaccuracies; the deliverability according to the number of control points and dose rates was investigated by using treatment machine log files and dosimetry devices, respectively. A non-negligible degradation in DCAT deliverability due to gantry wobble was observed in both the treatment machine log files and dosimetry devices. The resulting dose-delivery error occurred below a certain number of control points or above a certain dose rate. Dose simulations in the patient domain showed a similar impact on deteriorated deliverability. For targets located primarily in the isocenter, the dose differences were negligible, whereas for organs at risk located mainly off-isocenter, the dose differences were significant up to - 8.77%. To ensure safe and accurate radiotherapy, optimal plan parameters should be selected, and gantry angle-specific validations should be conducted before treatment.

Reuse of external fixation components: a randomized trial.

OBJECTIVES: External fixation devices are sold in the United States as single-use devices and can be costly. Approved processes for refurbishment of nonimplantable components are available. We evaluated one such program for safety, efficacy, and fiscal ramifications. DESIGN: Randomized clinical trial SETTING: Single center, Level I trauma center PATIENTS/PARTICIPANTS: During the 30-month enrollment period (November 16, 2001 to May 16, 2004), 41 patients (13%) of 315 patients were not able to consent and were excluded. A total of 178 (65%) of the 274 eligible patients who were offered entry into a randomized trial of new versus refurbished external fixation components for their injury refused to participate, leaving 96 (35%) of the 274 eligible patients entered into the study. INTERVENTION: Consented patients were entered into a trial of new versus refurbished nonimplantable external fixation components for their injury (all pins were new). MAIN OUTCOME MEASUREMENTS: The frames were evaluated at the time of removal for efficacy and the complications of pin tract infections, loss of fixation, or loosening of components. RESULTS: A total of 48 distal radius fractures, 29 pilon fractures, and 19 tibial plateau fractures were entered into the study. With the 96 fractures treated in our study (50 new frames, 46 reused frames), we found no statistical differences in the incidence of pin tract infections (46% versus 52%, P=0.32), loss of fixation (4% versus 4%, P=0.70), or loosening of the components (1% versus 1%, P=1.0). CONCLUSIONS: Sixty-five percent of consentable patients did not wish to have an external fixation frame with refurbished clamps. Our study demonstrated that this type of program is safe and effective with an actual cost savings of $65,452. The potential savings of such a program is 25% of the cost of all new frames.

The orthopaedic trauma literature: an evaluation of statistically significant findings in orthopaedic trauma randomized trials.

BACKGROUND: Evidence-based medicine posits that health care research is founded upon clinically important differences in patient centered outcomes. Statistically significant differences between two treatments may not necessarily reflect a clinically important difference. We aimed to quantify the sample sizes and magnitude of treatment effects in a review of orthopaedic randomized trials with statistically significant findings. METHODS: We conducted a comprehensive search (PubMed, Cochrane) for all randomized controlled trials between 1/1/95 to 12/31/04. Eligible studies include those that focused upon orthopaedic trauma. Baseline characteristics and treatment effects were abstracted by two reviewers. Briefly, for continuous outcome measures (ie functional scores), we calculated effect sizes (mean difference/standard deviation). Dichotomous variables (ie infection, nonunion) were summarized as absolute risk differences and relative risk reductions (RRR). Effect sizes >0.80 and RRRs>50% were defined as large effects. Using regression analysis we examined the association between the total number of outcome events and treatment effect (dichotomous outcomes). RESULTS: Our search yielded 433 randomized controlled trials (RCTs), of which 76 RCTs with statistically significant findings on 184 outcomes (122 continuous/62 dichotomous outcomes) met study eligibility criteria. The mean effect size across studies with continuous outcome variables was 1.7 (95% confidence interval: 1.43-1.97). For dichotomous outcomes, the mean risk difference was 30% (95%confidence interval:24%-36%) and the mean relative risk reduction was 61% (95% confidence interval: 55%-66%; range: 0%-97%). Fewer numbers of total outcome events in studies was strongly correlated with increasing magnitude of the treatment effect (Pearson's R = -0.70, p < 0.01). When adjusted for sample size, the number of outcome events revealed an independent association with the size of the treatment effect (Odds ratio = 50, 95% confidence interval: 3.0-1000, p = 0.006). CONCLUSION: Our review suggests that statistically significant results in orthopaedic trials have the following implications-1) On average large risk reductions are reported 2) Large treatment effects (>50% relative risk reduction) are correlated with few number of total outcome events. Readers should interpret the results of such small trials with these issues in mind.