Costlets: A Generalized Approach to Cost Functions for Automated Optimization of IMRT Treatment Plans

We present the creation and use of a generalized cost function methodology based on costlets for automated optimization for conformal and intensity modulated radiotherapy treatment plans. In our approach, cost functions are created by combining clinically relevant “costlets”. Each costlet is created by the user, using an “evaluator” of the plan or dose distribution which is incorporated into a function or “modifier” to create an individual costlet. Dose statistics, dose-volume points, biological model results, non-dosimetric parameters, and any other information can be converted into a costlet. A wide variety of different types of costlets can be used concurrently. Individual costlet changes affect not only the results for that structure, but also all the other structures in the plan (e.g., a change in a normal tissue costlet can have large effects on target volume results as well as the normal tissue). Effective cost functions can be created from combinations of dose-based costlets, dose-volume costlets, biological model costlets, and other parameters. Generalized cost functions based on costlets have been demonstrated, and show potential for allowing input of numerous clinical issues into the optimization process, thereby helping to achieve clinically useful optimized plans. In this paper, we describe and illustrate the use of the costlets in an automated planning system developed and used clinically at the University of Michigan Medical Center. We place particular emphasis on the flexibility of the system, and its ability to discover a variety of plans making various trade-offs between clinical goals of the treatment that may be difficult to meet simultaneously.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47484/1/11081_2005_Article_2066.pd

A large-scale multicentre study of patient skin doses in interventional cardiology: dose-area product action levels and dose reference levels.

For 318 patients in 8 different Belgian hospitals, the entire skin-dose distribution was mapped using a grid of 70 thermoluminescence dosimeters per patient, allowing an accurate determination of the maximum skin dose (MSD). Dose-area product (DAP) values, exposure parameters and geometry, together with procedure, patient and cardiologist characteristics, were also registered. Procedures were divided into two groups: diagnostic procedures (coronary angiography) and therapeutic procedures (dilatation, stent, combined procedures (e.g. coronary angiography + dilatation + stent)). The mean value of the MSD was 0.310 Gy for diagnostic and 0.699 Gy for therapeutic procedures. The most critical projection for receiving the MSD is the LAO90 (left anterior oblique) geometry. In 3% of cases, the MSD exceeded the 2 Gy dose threshold for deterministic effects. Action levels in terms of DAP values as the basis for a strategy for follow-up of patients for deterministic radiation skin effects were derived from measured MSD and cumulative DAP values. Two DAP action levels are proposed. A first DAP action level of 125 Gy cm(2) corresponding to the dose threshold of 2 Gy would imply an optional radiopathological follow-up depending on the cardiologist's decision. A second DAP action level of 250 Gy cm(2) corresponding to the 3 Gy skin dose would imply a systematic follow-up. Dose reference levels - 71.3 Gy cm(2) for diagnostic and 106.0 Gy cm(2) for therapeutic procedures - were derived from the 75 percentile of the DAP distributions. As a conclusion, we propose that total DAP is registered in patient's record file, as it can serve to improve the follow-up of patients for radiation-induced skin injuries

Skolans praktiska arbete för likvärdighet

Syftet med studien är att utforska och förtydliga vad likvärdighet idag uppfattas som hos skolans huvudmän, rektorer och lärare, samt hur likvärdighet eftersträvas inom grundskolan. Det finns en önskan om att uppmärksamma en problematik med strävan efter minskade resultatskillnader mellan elever som verkar motsäga likvärdighetsmålet att alla elever ska utvecklas så långt som möjligt. Studien har utförts i Linköpings kommun där huvudmän, rektorer och lärare inom grundskolans högstadie har intervjuats. Likvärdighet definieras av respondenterna som att ge alla elever samma möjlighet och samma chans. Detta genom en lyckad skolgång för att nå kunskapskraven samt möjlighet till maximal utveckling. Resultaten visar att små resultatskillnader mellan elever och mellan skolor inte eftersträvas, utan varje elevs maximala utveckling anses viktigare för likvärdigheten. Mätningar av elevers utveckling/progression är idag problematiskt, men enligt respondenterna vore det ett bättre mått på likvärdighet. Ett övergripande likvärdighetsmål för skolan är att alla elever ska nå de grundläggande målen, vilket sker genom extra resurser till svagpresterande elever. Högpresterande elevers behov förbises oftare

Interventional treatment in diabetics in the era of drugeluting stents and compliance to the ESC guidelines: Lessons learned from the Euro Heart Survey Programme

Aims: The objective of the study is to determine the demographics and the in-hospital outcome of diabetic and non-diabetic patients treated with percutaneous coronary interventions (PCI) in Europe, to report the type of equipment and technology used for PCI procedures in diabetics and to clarify whether the treatment of diabetic patients complies with current European Society of Cardiology (ESC) guidelines. Methods and results: A total of 14,458 patients treated with PCI were enrolled from 29 member countries of the ESC between June 2005 and January 2006. Data were collected on patient characteristics and treatment, using new Cardiology Audit and Registration Data standards. In total, 3,603 patients (24.9%) were diabetic. Diabetics were older, more often female and had a higher body mass index than non-diabetics. Diabetics had higher rates of hypercholesterolaemia and hypertension, while current smokers were more frequent in the non-diabetics. Diabetics also had significantly higher rates of previous cardiovascular events. Clopidogrel was administered only in 48.1% of diabetic patients before PCI, while IIb/IIIa inhibitors were 22.9% during PCI. At discharge, there was a major adjustment of treatment with increases in the use of Beta-blocker (80.4%), angiotensin converting enzyme inhibitor (ACEI, 71.3%) and statins (89.8%) compared with on admission (Beta-blocker 60.9%, ACEI 55.0%, statin 63.1%). Inhospital mortality was higher in diabetics (1.8% vs 1.2%) although the in-hospital MACCE rate was not significantly different (3.6% vs 3.0%, p=0.09). Conclusions: Diabetic patients treated with PCI were older with more comorbidity. According to ESC guideline, the under-usage of clopidogrel, GP IIb/IIIa inhibitors should be improved. PCI is now taken as a good opportunity to adjust the use of appropriate medication. © Europa Edition. All rights reserved