Single-fraction prostate stereotactic body radiotherapy: Dose reconstruction with electromagnetic intrafraction motion tracking.

PURPOSE: To reconstruct the dose delivered during single-fraction urethra-sparing prostate stereotactic body radiotherapy (SBRT) accounting for intrafraction motion monitored by intraprostatic electromagnetic transponders (EMT). METHODS: We analyzed data of 15 patients included in the phase I/II "ONE SHOT" trial and treated with a single fraction of 19 Gy to the planning target volume (PTV) and 17 Gy to the urethra planning risk volume. During delivery, prostate motion was tracked with implanted EMT. SBRT was interrupted when a 3-mm threshold was trespassed and corrected unless the offset was transient. Motion-encoded reconstructed (MER) plans were obtained by splitting the original plans into multiple sub-beams with isocenter shifts based on recorded EMT positions, mimicking prostate motion during treatment. We analyzed intrafraction motion and compared MER to planned doses. RESULTS: The median EMT motion range (±SD) during delivery was 0.26 ± 0.09, 0.22 ± 0.14 and 0.18 ± 0.10 cm in the antero-posterior, supero-inferior, and left-right axes, respectively. Treatment interruptions were needed for 8 patients because of target motion beyond limits in the antero-posterior (n = 6) and/or supero-inferior directions (n = 4). Comparing MER vs. original plan there was a median relative dose difference of -1.9% (range, -7.9 to -1.0%) and of +0.5% (-0.3-1.7%) for PTV D98% and D2%, respectively. The clinical target volume remained sufficiently covered with a median D98% difference of -0.3% (-1.6-0.5%). Bladder and rectum dosimetric parameters showed significant differences between original and MER plans, but mostly remained within acceptable limits. CONCLUSIONS: The dosimetric impact of intrafraction prostate motion was minimal for target coverage for single-fraction prostate SBRT with real-time electromagnetic tracking combined with beam gating.

Evaluation of a Placement Coaching Program for Recipients of Disability Insurance Benefits in Switzerland.

Purpose During 2009‒2013 a pilot project was carried out in Zurich which aimed to increase the income of disability insurance (DI) benefit recipients in order to reduce their entitlement to DI benefits. The project consisted of placement coaching carried out by a private company that specialized in this field. It was exceptional with respect to three aspects: firstly, it did not include any formal training and/or medical aid; secondly, the coaches did not have the possibility of providing additional financial incentives or sanctioning lack of effort; and thirdly due to performance bonuses, the company not only had incentives to bring the participants into (higher paid) work, but also to keep them there for 52 weeks. This paper estimates the medium-run effects of the pilot project and assesses the net benefit from the Swiss social security system. Methods Different propensity score matching estimators are applied to administrative longitudinal data in order to construct suitable control groups. Results The estimates indicate a reduction in DI benefits and an increase in income even in the medium-run. A simple cost-benefit analysis suggests that the pilot project was a profitable investment for the social security system. Conclusion Given a healthy labor market, it seems possible to enhance the employment prospects of disabled persons with a relatively inexpensive intervention, which does not include any explicit investments in human capital.