Performance of an automatic dose control system for CT: patient studies

PURPOSE

To study the effect of an automatic dose control (ADC) system with adequate noise characteristic on the individual perception of image noise and diagnostic acceptance compared to objectively measured image noise and the dose reductions achieved in a representative group of patients.

MATERIALS AND METHODS

In a retrospective study two matched cohorts of 20 patients each were identified: a manual cohort with exposure settings according to body size (small - regular - large) and an ADC cohort with exposure settings calculated by the ADC system (DoseRight 2.0™, Philips Healthcare). For each patient, 12 images from 6 defined anatomic levels from contrast-enhanced scans of chest and abdomen/pelvis were analyzed by 4 independent readers concerning image noise and diagnostic acceptance on a five-point Likert scale and evaluated for objectively measured image noise. Radiation exposure was calculated from recorded exposure data.

RESULTS

Use of the ADC system reduced the average effective dose for patients by 36 % in chest scans (3.2 vs. 4.9 mSv) and by 17 % in abdomen/pelvis scans (7.6 vs. 8.3 mSv). Average objective noise was slightly lower in the manual cohort (11.1 vs. 12.8 HU), correlating with a slightly better rating in subjective noise score (4.4 vs. 4.2). However, diagnostic acceptance was rated almost equal in both cohorts with excellent image quality (4.6 vs. 4.5).

CONCLUSION

Use of an ADC system with adequate noise characteristic leads to significant reductions in radiation exposure for patients while maintaining excellent image quality.

[CT-guided marking of pulmonary nodules with a special lung marking wire before video-assisted thoracoscopic surgery - review of 184 cases]

PURPOSE

Minimally invasive techniques like video-assisted thoracoscopic surgery (VATS) are currently the method of choice for the resection of small pulmonary nodules, when they are located in the periphery of the lungs. To guarantee quick and safe intraoperative identification of the nodule, preoperative marking is necessary and sensible. We report about our experiences in 184 markings with a special lung marking wire, which is placed in or around the pulmonary nodule using CT guidance.

MATERIALS AND METHODS

In 184 patients (97 m, 87f, mean age: 58.1 ± 13.7 years) with pulmonary nodules, scheduled for resection with VATS, a special lung marking wire was placed preoperatively under CT guidance. We evaluated the technical success, safety, necessity of conversion to thoracotomy and histology in all patients.

RESULTS

The marking wire could be positioned successfully in 181 cases (98.4 %). There was one major complication (uncontrollable pneumothorax). Minor adverse events like small pneumothorax (53.3 %) or a perifocal bleeding (30.4 %) did not necessitate treatment. Complete resection of the marked nodule was successful in 98.4 % of the patients. Conversion to thoracotomy was necessary in 29 patients (15.9 %) due to bleeding, adhesions, malignancy or wire dislocation. Histology revealed a benign nodule in 96 cases (54.4 %) and a malignant lesion in 78 cases (45.6 %), of which only 21 nodules (11.5 %) turned out to present a primary pulmonary carcinoma.

CONCLUSION

CT-guided marking of pulmonary nodules using a special marking wire followed by thoracoscopic resection is an efficient and safe method for diagnosing suspicious nodules in the periphery of the lung.

Imaging of the sinuses for functional sinus surgery using navigational guidance

Advances in the understanding of mucociliary activity and pathophysiology of the nasal cavity and paranasal sinuses have revolutionized the surgical management of chronic and recurrent sinusitis. The development of functional endoscopic sinus surgery (FESS) can also be seen as the pioneer task in endoscopic surgery. Today, in more than 50% of all sinus surgeries FESS is being used. Inflammatory causes are the most common indication for surgery, which can be evaluated best preoperatively using (multi-detector) computed tomography. Even today there are further relevant developments of FESS that result in alleviation of the surgeon due to different degrees of automation. Using a preoperatively acquired navigational dataset helps choosing the optimal surgical strategy. Intraoperatively the navigational dataset is at present mainly used for localization of surgical tools. These newer operation methods demand for high-quality radiological imaging and evaluation, consisting of delineation of the local (inflammatory) process, detection of disease related complications and description of anatomical variations that may be important to the surgeon. Since patients with chronic recurrent sinusitis are relatively young on average and recurrent disease or further CT examinations are not uncommon, there should always be a focus on reduction of radiation exposure as much as possible. Technical advances like cone-beam tomography seem promising to further improve dose reduction as well as spatial resolution.

Reducing the legal blood alcohol concentration limit for driving in developing countries: a time for change? Results and implications derived from a time-series analysis (2001-10) conducted in Brazil

AIMS

In Brazil, a new law introduced in 2008 has lowered the blood alcohol concentration limit for drivers from 0.06 to 0.02, but the effectiveness in reducing traffic accidents remains uncertain. This study evaluated the effects of this enactment on road traffic injuries and fatalities.

DESIGN

Time-series analysis using autoregressive integrated moving average (ARIMA) modelling.

SETTING

State and capital of São Paulo, Brazil.

PARTICIPANTS

  A total of 1,471,087 non-fatal and 51,561 fatal road traffic accident cases in both regions.

MEASUREMENTS

Monthly rates of traffic injuries and fatalities per 100,000 inhabitants from January 2001 to June 2010.

FINDINGS

The new traffic law was responsible for significant reductions in traffic injury and fatality rates in both localities (P<0.05). A stronger effect was observed for traffic fatality (-7.2 and -16.0% in the average monthly rate in the State and capital, respectively) compared to traffic injury rates (-1.8 and -2.3% in the State and capital, respectively).

CONCLUSIONS

Lowering the blood alcohol concentration limit in Brazil had a greater impact on traffic fatalities than injuries, with a higher effect in the capital, where presumably the police enforcement was enhanced.