45 research outputs found
A Millimeter-scale Single Charged Particle Dosimeter for Cancer Radiotherapy
This paper presents a millimeter-scale CMOS 6464 single charged
particle radiation detector system for external beam cancer radiotherapy. A
11 diode measures energy deposition by a single charged
particle in the depletion region, and the array design provides a large
detection area of 512512 . Instead of sensing the voltage drop
caused by radiation, the proposed system measures the pulse width, i.e., the
time it takes for the voltage to return to its baseline. This obviates the need
for using power-hungry and large analog-to-digital converters. A prototype ASIC
is fabricated in TSMC 65 nm LP CMOS process and consumes the average static
power of 0.535 mW under 1.2 V analog and digital power supply. The
functionality of the whole system is successfully verified in a clinical 67.5
MeV proton beam setting. To our' knowledge, this is the first work to
demonstrate single charged particle detection for implantable in-vivo
dosimetry
Description and dosimetric verification of the PEREGRINE Monte Carlo dose calculation system for photon beams incident on a water phantom
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134919/1/mp1551.pd
Effectiveness of Pharmacovigilance Training of General Practitioners A Retrospective Cohort Study in the Netherlands Comparing Two Methods
Background: Spontaneous reporting is a cornerstone of pharmacovigilance. Unfamiliarity with the reporting of suspected adverse drug reactions (ADRs) is a major factor leading to not reporting these events. Medical education may promote more effective reporting. Numerous changes have been implemented in medical education over the last decade, with a shift in training methods from those aimed predominantly at the transfer of knowledge towards those that are more practice based and skill oriented. It is conceivable that these changes have an impact on pharmacovigilance training in vocational training programmes. Therefore, this study compares the effectiveness of a skill-oriented, practice-based pharmacovigilance training method, with a traditional, lecture-based pharmacovigilance training method in the vocational training of general practitioners (GPs). The traditional, lecture-based method is common practice in the Netherlands. Objective: The purpose of this study was to establish whether the use of a practice-based, skill-oriented method in pharmacovigilance training during GP traineeship leads to an increase of reported ADRs after completion of this traineeship, compared with a lecture-based method. We also investigated whether the applied training method has an impact on the documentation level of the reports and on the number of unlabelled events reported. Study Design: A retrospective cohort study. The number of ADR reports submitted to the Netherlands Pharmacovigilance Centre Lareb (between January 2006 and October 2010) after completion of GP vocational training was compared between the two groups. Documentation level of the reports and the number of labelled/unlabelled events reported were also compared. Results: The practice-based cohort reported 32 times after completion of training (124 subjects, 6.8 reports per 1000 months of follow-up; total follow-up of 4704 months). The lecture-based cohort reported 12 times after training (135 subjects, 2.1 reports per 1000 months of follow-up; total follow-up of 5824 months) [odds ratio 2.9; 95% CI 1.4, 6.1]. Reports from GPs with practice-based training had a better documentation grade than those from GPs with lecture-based training, and more often concerned unlabelled events. Conclusions: The practice-based method resulted in significantly more and better-documented reports and more often concerned unlabelled events than the lecture-based method. This effect persisted and did not appear to diminish over time
Minimally Invasive Pyeloplasty in Horseshoe Kidneys with Ureteropelvic Junction obstruction: A case series
Background and Purpose Horseshoe kidney is an uncommon renal anomaly often associated with ureteropelvic junction (UPJ) obstruction. Advanced minimally invasive surgical (MIS) reconstructive techniques including laparoscopic and robotic surgery are now being utilized in this population. However, fewer than 30 cases of MIS UPJ reconstruction in horseshoe kidneys have been reported. We herein report our experience with these techniques in the largest series to date. Materials and Methods We performed a retrospective chart review of nine patients with UPJ obstruction in horseshoe kidneys who underwent MIS repair at our institution between March 2000 and January 2012. Four underwent laparoscopic, two robotic, and one laparoendoscopic single-site (LESS) dismembered pyeloplasty. An additional two pediatric patients underwent robotic Hellstrom repair. Perioperative outcomes and treatment success were evaluated. Results Median patient age was 18 years (range 2.5-62 years). Median operative time was 136 minutes (range 109-230 min.) and there were no perioperative complications. After a median follow-up of 11 months, clinical (symptomatic) success was 100%, while radiographic success based on MAG-3 renogram was 78%. The two failures were defined by prolonged t1/2 drainage, but neither patient has required salvage therapy as they remain asymptomatic with stable differential renal function. Conclusions MIS repair of UPJ obstruction in horseshoe kidneys is feasible and safe. Although excellent short-term clinical success is achieved, radiographic success may be lower than MIS pyeloplasty in heterotopic kidneys, possibly due to inherent differences in anatomy. Larger studies are needed to evaluate MIS pyeloplasty in this population
Precision response estimation, energy calibration, and unfolding of spectra measured with a large NaI detector
NRC publication: Ye
Measurement of multiple scattering of 13 and 20 MeV electrons by thin foils
To model the transport of electrons through material requires knowledge
of how the electrons lose energy and scatter. Theoretical models are used
to describe electron energy loss and scatter and these models are supported
by a limited amount of measured data. The purpose of this work was to obtain
additional data that can be used to test models of electron scattering. Measurements
were carried out using 13 and 20 MeV pencil beams of electrons produced by
the National Research Council of Canada research accelerator. The electron
fluence was measured at several angular positions from 0° to 9°
for scattering foils of different thicknesses and with atomic numbers ranging
from 4 to 79. The angle, θ1âe,
at which the fluence has decreased to 1âe of
its value on the central axis was used to characterize the distributions.
Measured values of θ1âe ranged
from 1.5° to 8° with a typical uncertainty of about 1%. Distributions
calculated using the EGSnrc Monte Carlo code were compared to the measured
distributions. In general, the calculated distributions are narrower than
the measured ones. Typically, the difference between the measured and calculated
values of θ1âe is
about 1.5%, with the maximum difference being 4%. The measured and calculated
distributions are related through a simple scaling of the angle, indicating
that they have the same shape. No significant trends with atomic number were
observed