Irregular surface compensation for radiotherapy of the breast: correlating depth of the compensation surface with breast size and resultant dose distribution.

Irregular surface compensation uses dynamic multileaf collimators to modify the fluence to an irregular surface along the cranio-caudal axis. The depth of the compensation surface can be varied by specifying a user-defined parameter called the transmission penetration depth (TPD). In our institution, a review has been carried out of 60 breast patients treated using irregular surface compensation of the tangent fields. The effect of changes in the TPD on the dose distribution was investigated, and the optimum TPD was correlated with the maximum field separation (S(max)) along the posterior border. Reducing the TPD below 50% pushes the dose towards the front of the breast. This reduces hot spots at the medial and lateral regions next to the posterior border of the tangential fields, particularly for patients with large separation. In 23/60 patients, with a mean S(max) of 23.9 +/- 1.6 cm, a TPD between 35% and 45% was used to reduce the proportion of the planning target volume receiving more than 107% of the prescribed dose by 3.4% +/- 2.8%. Our department protocol states that, subject to an acceptable dose distribution, a TPD of 40% is used if S(max) is greater than 24 cm; for smaller separations, a TPD of 50% is used.

A prospective clinical audit of central venous catheter use and complications in 1000 consecutive patients.

We conducted a prospective audit of central venous catheter (CVC) use in 1000 consecutive patients to better define the rates of postoperative complications (particularly vascular perforation) and the pattern of CVC and pulmonary artery catheter (PAC) usage (particularly the number of lumens inserted and utilized). Details of CVCs, complications, and the number of lumens in place and used, were recorded daily until all CVCs were removed. A total of 1546 CVCs and 223 PACs were placed in study patients. Two non-fatal perforations occurred: a perforated right atrium in a patient who received an Arrow triple-lumen CVC (previously reported), and a perforated pulmonary artery in a patient upon withdrawal of a Baxter PAC. The risk per patient of any CVC-related perforation was 0.2% (95% confidence interval (CI): 0.02% to 0.7%). The rates of CVC-related sepsis and local infection were 3% (95% CI: 2% to 4%) and 2% (95% CI: 1% to 3%) respectively. At the peak of CVC use (day 1 in the ICU) the overall number of lumens placed was significantly correlated with lumens used (r = 0.53), endorsing clinical judgement in the anticipation of the needs of the patient. The modal number of lumen uses in adults and children was four. However, in children, fewer catheters were inserted per patient than in adults (1.28 vs 1.63, P = 0.01), and placed lumens were used more intensively (P < 0.001). Data appear to justify the routine selection of a triple-lumen CVC in adult patients, but not of a quad-lumen CVC.

Cost-effectiveness of spinal cord stimulation in patients with intractable angina.

AIM: To review the cost of healthcare utilisation by patients suffering from intractable angina, unsuitable for coronary revascularisation, before and after treatment with spinal cord stimulation. METHODS: Data were collected for eight patients treated for intractable angina with spinal cord stimulation at Green Lane Hospital before April 1999. Information on consumption of specified medica resources for the twelve months preceding implantation, the implantation period, and the twelve months following implantation was collected. Where available, data were also collected for the eighteen months preceding and following treatment. RESULTS: In six patients successful permanent stimulation was established; in two it proved technically impossible to implant a stimulator. The six patients with successful stimulation spent fewer days in hospital (p=0.028) and consumed fewer resources (p=0.046) following implantation than in the period before implantation. The two patients for whom spinal cord stimulation was unsuccessful spent more days in hospital and consumed more resources in the twelve months following, than in the twelve months preceding attempted implantation. Extrapolation of data for all eight patients suggests that, on average, the cost of implanting a spinal cord stimulator will be recovered in approximately fifteen months. CONCLUSION: Spinal cord stimulation is a cost-effective treatment for intractable angina pectoris.