PubMed · 10251078
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W C Felch. 1981. PIQuA program to field test.. https://pubmed.ncbi.nlm.nih.gov/10251078/
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PURPOSE: The increasing complexity of radiotherapy highlights the need for accurate setup. This paper assesses the potential of position corrections, derived from the three-dimensional (3D) surface of the patient, in reducing positioning errors in patients undergoing conformal radiation therapy of the prostate. METHODS AND MATERIALS: Twenty patients undergoing conformal radiation therapy for prostate cancer had planning computed tomography (CT) scans and then weekly treatment CT scans over the course of their treatment. Patients were positioned on the CT table using three coplanar tattoo marks used for patient setup on the accelerator. Surfaces were computed from the planning CT (planning surface), and the treatment CT (treatment surfaces). Using a surface matching utility, the planning and treatment 3D surfaces were compared. The prostate was implicitly localized based on surface matching of the external contour and by matching the bony anatomy. The resultant prostate displacement after correction was assessed for the two localization methods. RESULTS: Correcting patient position via the surface comparisons reduced the standard deviation of prostate displacement with respect to the patient isocenter in the lateral and anterior/posterior directions. In the lateral direction, prostate and surface motion was highly correlated (r = 0.96). In the anterior/posterior direction the corrections from the surface data were as effective as those derived from the bony anatomy. CONCLUSION: Detailed surface data can aid the positioning of patients receiving conformal radiation therapy to the prostate by reducing the displacement of the target from the intended treatment position. This study shows that surface corrections can be as effective as those derived from bony anatomy, and may be exploited where definition of bony anatomy is difficult.
OBJECTIVES: To assess the efficacy and feasibility of IUD insertion immediately after expulsion of the placenta. Our a priori hypothesis was that this practice is safe but associated with higher expulsion rates than interval IUD insertion. SEARCH STRATEGY: We used MEDLINE, Popline, EMBASE, and Cochrane Controlled Trials Register computer searches, supplemented by review articles and contact with investigators. SELECTION CRITERIA: We sought all randomized controlled trials that had at least one treatment arm that involved immediate post-partum (within ten minutes of placental expulsion) insertion of an IUD. Comparisons could include different IUDs, different insertion techniques, immediate vs. delayed post-partum insertion, or immediate vs. interval insertion (unrelated to pregnancy). Studies could include either vaginal or cesarean deliveries. DATA COLLECTION AND ANALYSIS: We evaluated the methodological quality of each report and sought to identify duplicate reporting of data from multicenter trials. We abstracted data onto data collection forms. Principal outcome measures included pregnancy, expulsion, and continuation rates. Because the trials did not have uniform interventions, we were unable to aggregate them in a meta-analysis. MAIN RESULTS: We found no randomized controlled trials that directly compared immediate post-partum insertion with either delayed post-partum or interval insertion. Modifications of existing devices, such as adding absorbable sutures or additional appendages, did not appear beneficial. Most studies showed no important differences between insertions done by hand or by instruments. Lippes Loops and Progestasert devices did not perform as well as did copper devices. REVIEWER'S CONCLUSIONS: Immediate post-partum insertion of IUDs appeared safe and effective, though direct comparisons with other insertion times were lacking. Advantages of immediate post-partum insertion include high motivation, assurance that the woman is not pregnant, and convenience. However, expulsion rates appear to be higher than with interval insertion. The popularity of immediate post-partum IUD insertion in countries as diverse as China, Mexico, and Egypt support the feasibility of this approach. Early follow-up may be important in identifying spontaneous IUD expulsions.
The use of chemical categories has been suggested in order to lower the number of chemicals tested in the High Production Volume (HPV) Chemical Challenge Program. In this investigation we examined the reliability of using organic chemical categories to classify chemicals as either toxic or nontoxic for individual toxicological effects as well as for panels of such endpoints. The analyses indicate that chemical categories are unable to consistently identify groups of chemicals with similar toxic responses either for a multiplicity of endpoints or for single effects. Our analyses suggest that if chemical categories are to be used to identify health hazards, that computer-based SAR approaches appear to be superior to arbitrary chemical categories for predicting specific toxicological effects but they are not, at this time, useful for defining the overall toxicity.