Anatoly Rozenfeld

Energy Conservation in Large Buildings

A. Rosenfeld et al. — Tue, 11 Sep 2012 20:36:51 PDT

As energy prices rise, newly energy aware designers use better tools and technology to create energy efficient buildings. Thus the U.S. office stock (average age 20 years) uses 250 kBTU/ft² of resource energy, but the guzzler of 1972 uses 500 (up × 2), and the 1986 ASHRAE standards call for 100–125 (less than 25% of their 1972 ancestors). Surprisingly, the first real cost of these efficient buildings has not risen since 1972. Scaling laws are used to calculate heat gains and losses of buildings to obtain the ΔT(free) which can be as large as 15–30 °C (30–60 °F) for large buildings. The net thermal demand and thermal time constants are determined for the Swedish Thermodeck buildings which need essentially no heat in the winter and no chillers in summer. The BECA and other data bases for large buildings are discussed. Off-peak cooling for large buildings is analyzed in terms of saving peak-electrical power. By downsizing chillers and using cheaper, off-peak power, cost-effective thermal storage in new commercial buildings can reduce U.S. peak power demands by 10–20 GW in 15 years. A further potential of about 40 GW is available from adopting partial thermal storage and more efficient air conditioners in existing buildings.

In vivo dosimetry and seed localization in prostate brachytherapy with permanent implants

A. Rosenfeld et al. — Tue, 11 Sep 2012 20:36:49 PDT

This paper reports on the development of an interactive, intraoperative dose planning system for seed implant brachytherapy in cancer treatment. This system involves in vivo dosimetry and the ability to determine implanted seed positions. The first stage of this project is the development of a urethral alarm probe to measure the dose along the urethra during a prostate brachytherapy treatment procedure. Ultimately, the system will be used to advise the physicians upon reaching a preset dose rate or dose after total seed decay in the urethra during the seed placement. The second stage is the development of a method and instrumentation for in vivo measurements of the location of implanted seeds in the same frame as for dose planning and the use of these in intraoperative treatment planning. We have developed a silicon mini-detector, miniature front-end, and shaping amplifier with discriminator, connected to the mini-silicon detector at the end of a cable placed in a urological catheter, to satisfy the spectroscopic requirements of the urethral probe. This technique will avoid complications related to overdosing the urethra and the rectum.

A method for measuring tissue-equivalent dose using a pin diode and activation foil in epithermal neutron beams with En < 100 keV

Martin G. Carolan et al. — Tue, 11 Sep 2012 20:36:48 PDT

MOSFET dosimetry with high spatial resolution in intense synchrotron-generated xray microbeams

Heidi Nettelbeck et al. — Tue, 11 Sep 2012 20:36:47 PDT

Method of Monte Carlo simulation verification in hadron therapy with non-tissue equivalent detectors

Andrew Wroe et al. — Tue, 11 Sep 2012 20:36:45 PDT

Experimental investigation of the 100 keV x-ray dose response of the high-temperature thermoluminescence in Lif: Mg, Ti (TLD-100): theoretical interpretation using the unified interaction model

Michael L. Lerch et al. — Tue, 11 Sep 2012 20:36:44 PDT

Design and fabrication of pulmonary embolism phantom for planar and SPECT V/Q imaging quality assurance

Steven B. Harvey et al. — Tue, 11 Sep 2012 20:36:43 PDT

In vivo real-time rectal wall dosimetry for prostate radiotherapy

Nicholas Hardcastle et al. — Tue, 11 Sep 2012 20:36:41 PDT

Rectal balloons are used in external beam prostate radiotherapy to provide reproducible anatomy and rectal dose reductions. This is an investigation into the combination of a MOSFET radiation detector with a rectal balloon for realtime in vivo rectal wall dosimetry. The MOSFET used in the study is a radiation detector that provides a water equivalent depth of measurement of 70 μm. Two MOSFETs were combined in a face-to-face orientation. The reproducibility, sensitivity and angular dependence were measured for the dual MOSFET in a 6 MV photon beam. The dual MOSFET was combined with a rectal balloon and irradiated with hypothetical prostate treatments in a phantom. The anterior rectal wall dose was measured in real time and compared with the planning system calculated dose. The dual MOSFET showed angular dependence within ±2.5% in the azimuth and +2.5%/−4% in the polar axes. When compared with an ion chamber measurement in a phantom, the dual MOSFET agreed within 2.5% for a range of radiation path lengths and incident angles. The dual MOSFET had reproducible sensitivity for fraction sizes of 2–10 Gy. For the hypothetical prostate treatments the measured anterior rectal wall dose was 2.6 and 3.2% lower than the calculated dose for 3DCRT and IMRT plans. This was expected due to limitations of the dose calculation method used at the balloon cavity interface. A dual MOSFET combined with a commercial rectal balloon was shown to provide reproducible measurements of the anterior rectal wall dose in real time. The measured anterior rectal wall dose agreed with the expected dose from the treatment plan for 3DCRT and IMRT plans. The dual MOSFET could be read out in real time during the irradiation, providing the capability for real-time dose monitoring of the rectal wall dose during treatment.

A silicon strip detector dose magnifying glass for IMRT dosimetry

Sutinder Khanna et al. — Tue, 11 Sep 2012 20:36:40 PDT

Comparison of the New MOSkin Detector and Fiber Optic Dosimetry System for Radiotherapy

Ian Kwan et al. — Tue, 11 Sep 2012 20:36:38 PDT

Potential high resolution dosimeters for MRT

E Brauer-Krisch et al. — Tue, 11 Sep 2012 20:36:37 PDT

Characterisation of delta E-E particle telescope using the ANSTO heavy ion microprobe

Andrew Wroe et al. — Tue, 11 Sep 2012 20:36:35 PDT

Transferring advanced physics research tools to education: how to teach simulation tools used in radiation physics research to university students

Susanna Guatelli et al. — Tue, 11 Sep 2012 20:36:34 PDT

At the Centre of Medical Radiation Physics (CMRP), School of Engineering Physics, Faculty of Engineering, at the University of Wollongong (UOW), we are implementing a hands-on computing laboratory, commencing in autumn 2010, to teach scientific computing methods and modern, advanced research tools for radiation physics to postgraduate and undergraduate students. Engaging undergraduates and postgraduates together in work with a tool widely used in research laboratories is a unique development, and represents the articulation of the University’s commitment to the enhancement of the teaching/research nexus, and to the development of learning communities. The object of the laboratory is to teach students how to use Geant4 in the study of radiation physics related problems. Geant4 (www.cern.ch/geant4) is a Monte Carlo Simulation Toolkit, describing the interactions of particles with matter. It is widely used in research laboratories all over the world, from High Energy Physics to medical physics and space science. While the Geant4 Collaboration organizes courses all around the world to familiarise researchers and postgraduates with the Toolkit, insufficient attention is paid to undergraduates. The objectives of our program are that, upon completion of the practical laboratory, the students will be familiar with radiation physics and its applications, software development methods, computing instruments for research, the Monte Carlo approach, and the C++ language. They will also have had a unique opportunity to improve their problem solving skills and research methodologies. The design of the Geant4 hands-on lab faces two important issues: the heterogeneous computing skills and differing knowledge of radiation physics amongst students. Independent of their education grade, students have different expertise with programming, and computing matters in general. This problem can easily be overcome as Geant4 is developed for use by those with minimal computing expertise. However, the correct use of Geant4 requires a deep knowledge of radiation physics; this poses the second issue faced. The higher levels of motivation of postgraduate students will be one factor supporting undergraduates, in that working with Geant4 should foster a learning community, with peer learning and teaching occurring, and also provide undergraduates with a sense of future. Furthermore, we think we can overcome the problem of lower levels of knowledge through designing a guided hands-on course, providing Geant4 simulation exercises for students, based on their level of preparation. This course has high potential to increase the commitment of students towards radiation physics.

Evaluation of pixellated, back-sided planar photodetectors for high-resolution imaging instrumentation

Michael L. Lerch et al. — Tue, 11 Sep 2012 20:36:32 PDT

Surface dosimetry for breast radiotherapy in the presence of immobilization cast material

Andrew Kelly et al. — Tue, 11 Sep 2012 20:36:31 PDT

Curative breast radiotherapy typically leaves patients with varying degrees of cosmetic damage. One problem interfering with cosmetically acceptable breast radiotherapy is the external contour for large pendulous breasts which often results in high doses to skin folds. Thermoplastic casts are often employed to secure the breasts to maintain setup reproducibility and limit the presence of skin folds. This paper aims to determine changes in surface dose that can be attributed to the use of thermoplastic immobilization casts. Skin dose for a clinical hybrid conformal/IMRT breast plan was measured using radiochromic film and MOSFET detectors at a range ofwater equivalent depths representative of the different skin layers. The radiochromic film was used as an integrating dosimeter, while the MOSFETs were used for real-time dosimetry to isolate the contribution of skin dose from individual IMRT segments. Strips of film were placed at various locations on the breast and the MOSFETs were used to measure skin dose at 16 positions spaced along the film strips for comparison of data. The results showed an increase in skin dose in the presence of the immobilization cast of up to 45.7% and 62.3% of the skin dose without the immobilization cast present as measured with Gafchromic EBT film and MOSFETs, respectively. The increase in skin dose due to the immobilization cast varied with the angle of beam incidence and was greatest when the beam was normally incident on the phantom. The increase in surface dose with the immobilization cast was greater under entrance dose conditions compared to exit dose conditions.

Monte Carlo study of the potential reduction in out-of-field dose using a patient-specific aperture in pencil beam scanning proton therapy

Stephen J. Dowdell et al. — Tue, 11 Sep 2012 20:36:29 PDT

This study is aimed at identifying the potential benefits of using a patientspecific aperture in proton beam scanning. For this purpose, an accurate Monte Carlo model of the pencil beam scanning (PBS) proton therapy (PT) treatment head at Massachusetts General Hospital (MGH) was developed based on an existing model of the passive double-scattering (DS) system. The Monte Carlo code specifies the treatment head at MGH with sub-millimeter accuracy. The code was configured based on the results of experimental measurements performed at MGH. This model was then used to compare out-of-field doses in simulated DS treatments and PBS treatments. For the conditions explored, the penumbra in PBS is wider than in DS, leading to higher absorbed doses and equivalent doses adjacent to the primary field edge. For lateral distances greater than 10 cm from the field edge, the doses in PBS appear to be lower than those observed for DS. We found that placing a patient-specific aperture at nozzle exit during PBS treatments can potentially reduce doses lateral to the primary radiation field by over an order of magnitude. In conclusion, using a patient-specific aperture has the potential to further improve the normal tissue sparing capabilities of PBS.

High resolution entry and exit Monte Carlo dose calculations from a linear accelerator 6 MV beam under influence of transverse magnetic fields

Bradley M. Oborn et al. — Tue, 11 Sep 2012 20:36:27 PDT

Geant4 simulation of the CERN-EU high-energy reference field (CERF) facility

Dale Prokopovich et al. — Tue, 11 Sep 2012 20:36:26 PDT

Assessment of out-of-field absorbed dose and equivalent dose in proton fields

Andrew Wroe et al. — Tue, 11 Sep 2012 20:36:25 PDT

Radiation monitoring in mixed environments at CERN: from the IRRAD6 facility to the LHC experiments

A Holmes-Siedle et al. — Tue, 11 Sep 2012 20:36:23 PDT