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Upstate Loretta C. Ford
Education Wing Auditorium, Helen Wood Hall University of
Rochester Medical Center, 255 Crittenden Blvd., Rochester NY 14642 |
12:00 pm – 5:00 pm
Sponsoring Vendor Exhibits:
Resonant
Medical Inc. Varian Medical Systems TomoTherapy, Inc.
BrainLAB
AG
CIVCO Medical Solutiosn Upstate Linac Services, LLC Sun Nuclear
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10:00 |
Business Meeting |
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11:30 |
Lunch Sponsored
by Upstate Linac Services, LLC |
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12:00 |
Refreshments and Vendor Exhibits – Sengupta Room Sponsored by Sun Nuclear |
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12:25 |
Meeting
Introduction |
Walter O’Dell
Ph.D., UNYAPM President |
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Vendor Session |
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12:30 |
Virtual
Environment Radiotherapy Training (VERT) |
Andy Beavis, Ph.D., Vertual Ltd. |
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12:45 |
Modern Rotational Dosimetry: 2D and 4D |
Jie Shi, Ph.D., SUN Nuclear |
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Proffered Paper Session |
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1:00 |
The development of
a region of interest (ROI) angiography system for clinical use. |
Weiyuan
Wang, C Ionita, C Keleshis, A Kuhls, A Jain, D Bednarek, S Rudin |
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1:15 |
Flow
analysis of aneurysms treated with self-expanding asymmetric vascular stents
(SAVS) using digital subtracted angiography |
Ciprian Ionita, W
Wang, D Bednarek, S Rudin |
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1:30 |
Task Group proposal
for Simulation Training and Error Reduction in Medical Physics |
Michael
C. Schell, P Halverson,
D VerEllen, and A Beavis |
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1:50 |
Refreshments and Vendor Exhibits – Vestibule Sponsored by Sun
Nuclear |
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2:30 |
Demonstration
and comparison of contrast and spatial resolution between Single Photon Counting
and Energy Integrating modes for the newly developed high-resolution
Micro-Angiographic Fluoroscopic detector |
Amit Jain, A. Kulhs-Gilcrist, D. Bednarek, S. Rudin |
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2:48 |
Measuring
the MTF without slits, edges, or other test objects |
Andrew
Kuhls-Gilcrist, A Jain, D
Bednarek, S Rudin |
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3:06 |
Dosimetric
Correction for Lung Aperature used in Mouse Irradiation Experiments for a 250
kVp Orthovoltage Unit |
Cameron
D. Arndt, Z. Wang, N. Saito, M.B. Podgorsak |
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3:24 |
External
Beam Dose Perturbation from Implanted Seeds, Fiducial Markers and Surgical
Clips for Radiotherapy |
James
P. Steinman, HK Malhotra |
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3:42 |
An
alternative method for beam output constancy measurements |
Dinko Plenkovich |
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4:00 |
Refreshments and Vendor Exhibits – Vestibule Sponsored by Sun
Nuclear |
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Invited Speaker Session |
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4:25 |
Life
time achievement award winner Introduction |
Michael
Schell Ph.D., UNYAPM
President-Elect |
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4:30 |
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David Rogers Ph.D. |
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5:30 |
Award
Presentation |
Walter O’Dell Ph.D., UNYAPM President |
Driving Directions to the University of Rochester Medical
Center, Helen Wood Hall, 255 Crittenden Blvd
From the West: New York State Thruway to Exit 47.
- Take exit #47/LEROY (RT-19)/ROCHESTER
onto I-490 E (Toll applies) - go 19.63 mi
- Take exit #9B/AIRPORT onto I-390
S - go 2.9
- Take exit #17/SCOTTSVILLE RD. -
go 0.2 mi
- Turn Left on SCOTTSVILLE RD(RT-383)
- go 0.6 mi
- Bear Right on ELMWOOD AVE - go 0.7 mi
- Turn Right on Kendrick Rd - go 0.2 mi
- Turn Left on Crittenden Blvd - go 0.2 mi
Parking is available in the Visitors lot next to Helen Wood Hall, and also in Ramp Garage.
From Rochester Airport (ROC):
- Take exit #9B/AIRPORT onto I-390
S - go 2.9
- Take exit #17/SCOTTSVILLE RD. -
go 0.2 mi
- from there follow the directions as above
From the East: New York State Thruway to Exit 46.
- Take exit #46/ROCHESTER/CORNING onto I-390
N toward ROCHESTER (Toll applies) - go 6.9mi
- Take exit #16/E HENRIETTA RD/W
HENRIETTA RD (RT-15) - go 0.2
mi
- Turn Right on E HENRIETTA RD(RT-15A)
- go 0.9 mi
- Bear Right on MT HOPE AVE(RT-15)
- go 0.2 mi
- Turn Left on Crittenden Blvd - go 0.3 mi
From the South: 390 North and follow the directions above when coming from the East.
UNYAPM FALL 2009 MEETING PROCEEDINGS
University
of Rochester Medical Center, Helen Wood Hall, Rochester, NY
November 18, 2009
Virtual Environment Radiotherapy Training (VERT)
Andy Beavis, Ph.D.,
Vertual Ltd.
The development of a
region of interest (ROI) angiography system for clinical use
Weiyuan
Wang, Ciprian Ionita, Christos Keleshis, Andrew Kuhls, Amit Jain, Daniel
Bednarek, Stephen Rudin
Toshiba Stroke Research Center, SUNY Buffalo,
Buffalo NY
Due to the high-resolution needs of
angiographic and interventional vascular imaging, a Micro-Angiographic
Fluoroscope (MAF) detector with a Control, Acquisition, Processing, and Image
Display System (CAPIDS) was installed on a detector changer which was attached
to the C-arm of a clinical angiographic unit.
The MAF detector provides high-resolution and real-time imaging and
consists of a 300 µm CsI phosphor, a dual stage micro-channel plate light image
intensifier (LII) coupled to a fiber optic taper (FOT), and a fast-frame-rate,
progressive-scan, frame-transfer CCD camera providing 1024x1024 pixels with 12
bit depth. The changer allows the MAF or
a Solid-State X-ray Image Intensifier (SSXII) region-of-interest (ROI) detector
to be inserted in front of the standard flat-panel detector (FPD) when higher
resolution is needed during angiographic or interventional vascular imaging
procedures. The CAPIDS developed and
implemented using LabVIEW software provides a user-friendly interface that
allows control of several clinical radiographic imaging modes using the MAF or
SSXII including: fluoroscopy, roadmapping, radiographic mode, and digital-subtraction-angiography
(DSA). Additional features of CAPIDS,
including recursive filtering, contrast enhancement, patient registry and image
archival have been implemented and should facilitate the clinical use of the
MAF- or SSXII-based dual-detector system.
The total system has been used for image guidance during endovascular
image-guided interventions (EIGI) using prototype self-expanding asymmetric
vascular stents (SAVS) in over 10 rabbit aneurysm creation and treatment
experiments which have demonstrated the system's potential capability for
future clinical use.
Flow analysis of
aneurysms treated with self-expanding asymmetric vascular stents (SAVS) using
digital subtracted angiography
Ciprian
N. Ionita, Weiyuan Wang, Daniel R. Bednarek, Stephen Rudin
Department of Neurosurgery, SUNY Buffalo,
Buffalo NY
Purpose: To quantify
hemodynamic modification in animal model aneurysms caused by image-guided
deployment of a new self-expanding asymmetric vascular stent (SAVS) using x-ray
contrast digital subtraction angiography (DSA) thus providing an indication of
expected treatment outcome.
Materials
and Methods:
A nitinol-SAVS containing a low porosity patch to cover only the aneurysm neck
was used to treat five rabbit-model aneurysms. Contrast flow in the aneurysm
dome was recorded before-treatment, and after-treatment, using rapid-sequence
(15 fps) DSA. The DSAs were analyzed using time-density curves (TDC) measuring
the contrast in the aneurysm as a function of frame-time for each case. The
TDCs were normalized to the maximum value of the initial curve
(before-treatment).
Results: Before-treatment
TDC’s showed clearance of the contrast from the aneurysm dome in less than 3
seconds indicating strong blood flow in the dome. Post-treatment TDC’s showed
in 3 of 5 cases negligible contrast entering the aneurysms (almost 100% drop in
the TDC peak), 1 of the 5 had strong inflow followed by prologue contrast
residence in the dome, and the last of the 5 had moderately reduced flow (75%
of the initial peak), fast clearance, however only a remnant neck was observed
at 30 day follow-up. TDC’s generated
from the DSA acquisitions of the Nitinol-SAVS-treated aneurysms indicated
drastic reduction of the hemodynamic flow in the aneurysm dome and completely
successful treatment except for the one case where incomplete treatment was
predicted by only moderate flow modification.
Conclusions: Changes in
angiographically derived TDC’s appear to be a very useful tool to predict
treatment outcome. Based on TDC-analysis, the new Nitinol-SAVS is a very
promising option for treatment of intracranial aneurysms. (Support:
NIH-R01NS43924, NIH-R01EB002873)
Task Group proposal
for Simulation Training and Error Reduction in Medical Physics
Michael
C. Schell, Per Halverson, Dirk VerEllen, and Andrew Beavis
Department of Radiation Oncology, University
of Rochester Medical Center, Rochester NY
According
to IAEA Safety Report Series No. 17(1) and the Radiation Risk
Profile by the WHO(2), lack of training plays a key role in many
misadministrations in radiation oncology. Error reduction is greatly enhanced
by training on all levels. It is assumed that the physicist fulfills the basic
AAPM definition of a credentialed medical physicist and is board certified by
the American Board of Medical Physics or the American Board of Radiology.
Requisite training on all technology is an obvious requirement.
One
aspect of training is frequently overlooked. Ongoing training is essential to error reduction and a safe
treatment environment. The medical field focuses on continuing medical
education (CME) to ensure competence. CME can be fulfilled by quizzes and
journal reading and meeting attendance. CME does not test on actual performance
of professionals in the workplace in stressful conditions where procedures
fail. Consider the training policy of a nuclear power plant, such as the Ginna
nuclear power plant in upstate New York. The technologists and engineers
receive two full weeks of training each year. The training includes simulator
training that tests the personnel for the proper response to various failure
modes. The nuclear power plant operators train every sixth week for every
possible operation. A professional fireman typically receives two weeks
training per year. In contrast to these training policies, how does any medical
field fare? Training and testing of medical professionals in simulated
conditions is at best amateurish. Ongoing training typically is 2 days per year
for a few departmental clinicians rather than the entire department. Thus weak
or non-existent ongoing training erodes the infrastructure of the department as
memories fade and personnel turnover takes it toll.
The
Task Group goals and an overview of simulation training will be presented.
Demonstration and
comparison of contrast and spatial resolution between Single Photon Counting
(SPC) and Energy Integrating (EI) modes for the newly developed high-resolution
Micro-Angiographic Fluoroscopic (MAF) detector
Amit Jain, A. Kulhs-Gilcrist, D. R. Bednarek, S. Rudin
Toshiba Stroke Research Center, University at
Buffalo, Buffalo 14214 NY
Abstract:
Although
in radiological imaging, the prevailing mode of acquisition is to integrate the
energy deposited by all x-rays absorbed by the imaging detector, much
improvement in image spatial and contrast resolution could be achieved if each
individual x-ray photon were detected and counted separately. In this work we
compare the conventional energy integration (EI) mode with the new single
photon counting (SPC) mode for a recently developed high-resolution Micro-Angiographic
Fluoroscopic (MAF) detector, which is uniquely capable of both modes of
operation.
The MAF has 1024x1024 pixels of 35 microns effective size and is capable
of real-time imaging at 30 fps. The large variable gain of its light image intensifier
(LII) provides quantum limited operation with essentially no additive
instrumentation noise and enables the MAF to operate in both EI and the very
sensitive low-exposure SPC modes. We used high LII gain with very low exposure
(<1 x-ray photon/pixel) per frame for SPC mode and higher exposure with
lower gain for EI mode. Multiple signal-thresholded frames were summed in SPC
mode to provide an integrated frame with the same total exposure as EI mode. A
heavily K-edge filtered x-ray beam (average energy of 31 keV) was used to
provide a nearly monochromatic spectrum.
The MTF measured using a standard slit method showed a dramatic
improvement for the SPC mode over the EI mode at all frequencies. Images of a
line pair phantom also showed improved spatial resolution with 11 lp/mm visible
in SPC mode compared to only 8 lp/mm in EI mode. In SPC mode, images of human
distal and middle phalanges showed the trabecular structures of the bone with
far better contrast and detail. This improvement with the SPC mode should be
advantageous for clinical applications where high resolution is essential such
as in mammography and extremity imaging as well as for dual modality
applications, which combine nuclear medicine and x-ray imaging using a single
detector.
Measuring the MTF
without slits, edges, or other test objects
Andrew
Kuhls-Gilcrist, Amit Jain, Danial R. Bednarek, and Stephen Rudin
SUNY Buffalo, Buffalo NY
Purpose:
To
provide a new method for measurement of the modulation transfer function (MTF)
using the noise response of digital radiography systems.
Method
and Materials: Cascaded
linear system methods have been used for several decades to accurately predict
the signal and noise performance of a wide variety of digital x-ray imaging
technologies including x-ray image intensifiers, direct and indirect flat-panel
detectors (FPDs), and CCD/EMCCD-based detectors. The noise response of such
imagers inherently incorporates the detector resolution response, i.e. the
detector MTF. In this work, a generalized linear systems analysis was used to
derive an exact relationship. The two-dimensional noise power spectrum (NPS)
was plotted versus the mean signal level, for all spatial-frequencies. A linear
regression was fitted to this data to isolate the quantum-noise component, the
shape of which depends in part on the system resolution. The spatial-frequency
response of the resulting slopes was then used to obtain the MTF. The accuracy
of this method was investigated using simulated images from a simple detector
model, based on high-resolution EMCCD detectors, in which the MTF was known
exactly. Measurements were also done on a FPD and the results were compared
using the standard edge response method.
Results:
The
MTF measured from the noise response of the simulated detector system showed
exceptional agreement with the “true MTF” at both low and high spatial-frequencies. Differences of
0.3%, 1.8% and 6.1% were observed at 5, 10 and 15cycles/mm, respectively. The
FPD MTF obtained using the noise and edge response methods were also shown to
agree within experimental uncertainty.
Conclusions:
Initial
results indicate that the noise response method is a simple technique which can
be used to accurately measure the MTF (in all directions simultaneously) of
digital x-ray imagers, alleviating the burdens of development and
implementation of precision edge or slit devices.
Dosimetric Correction
for Lung Aperature used in Mouse Irradiation Experiments for a 250 kVp
Orthovoltage Unit
Cameron
D. Arndt, Z. Wang, N. Saito, M. B. Podgorsak,
Roswell Park Cancer Institute, Buffalo, NY
Purpose: Mice lung
irradiation experiments are being carried out to investigate radiation induced
pulmonary fibrosis. The irradiation setup involved a mouse pie cage device to
irradiate 10 mice simultaneously and radiation shields to protect critical
organs. The objective of this study was to evaluate the dosimetric effect of a
lung aperture located at an off-axis location.
Method
and Materials:
The irradiator is a Philips RT 250 orthovoltage unit with a 12.5 cm diameter
cone and 250 kVp X-rays which were used for irradiation. We used Gafchromic
EBT-2 film as the relative dose measurement tool in this study. To ensure
Gafchromic film measurement is accurate, we first compared percentage
depth dose (PDD) measurements to ion chamber measured beam data. The
concentric radiation shields were made of 0.5 cm thick Cerrobend, which leaves
only the mice lung regions open with a 1.2 cm width ring. The lung aperture is
approximately 4.5 cm away from the center of the cone. Effects of a 1-cm
airgap, off-axis effects and shielding effects were studied.
Results: The PDDs measured
using Gafchromic films matched well with the ion chamber data with very minimal
errors when depth < 2 cm (essentially thickness of a typical mouse in the
AP/PA direction), which validated the Gafchromic film dose measurement
accuracy. The effects of the 1 cm space were 7% drop in dose, essentially
inverse square fall off. There was 7% drop in dose from off-axis effects, and
shielding further dropped the dose 6%. The off-axis PDD curves
also showed a 4% decrease within the first 2 cm in
depth with the ring-shape aperture.
Summary: The dose to the
lungs of the mouse from the effects mentioned above was a 24% decrease in dose.
More accurate dose delivery will be achieved when the correction factors are
applied.
External Beam Dose
Perturbation from Implanted Seeds, Fiducial Markers and Surgical Clips in
Radiotherapy
James P. Steinman, H.K. Malhotra
Roswell Park Cancer Institute, SUNY Buffalo, Buffalo
NY
Purpose:
Suboptimal dose distributions from brachytherapy seed implants are often
salvaged by additional radiation using 3DCRT/IMRT. External beam therapy often
follows surgery which may involve many surgical clips. Fiducial markers are used in defining the
tumor site or as a surrogate in imaging for tumor localization. In standard treatment planning, the
dosimetric perturbations by the seeds/fiducial markers/surgical clips are
usually ignored. Present study aims at
characterizing these perturbations for 6MV and 18MV beams within a phantom
setting immediately above and below non-radioactive I-125, Pd-103, Cs-131
seeds, Gold fiducial markers, Copper, Aluminum, and Titanium clips.
Methods and Materials: A seed/fiducial marker/clip was
placed on a Lucite plate at 100cm SSD on 10cm Solid Water. Two Kodak X-Omat V films were placed on top
of the Lucite beneath 5cm Solid Water. A
1cmx1cm field was irradiated with 10MU at 6MV and 18MV. For measurements behind the seed, the setup
was similar but three films placed underneath the Lucite plate. Control field was irradiated with no
seed. The films were scanned using a
Vidar VXR-16 scanner and analyzed using RIT 113 Version 5.1. All films were taken from the same batch and
processed together.
Results: For
I-125 seeds, dose enhancement upstream was found to be 6.3% while dose
attenuation downstream was -10.9% compared with no seed on the films touching
the seed at 6MV. The greatest effect was
by the Gold Markers where the perturbation was 27.8% and -24.7% and least by
Aluminum, 3.0% and -8.6%. The dose
perturbation fell rapidly with distance and nearly vanished beyond ~2 mm.
Conclusion: The
dose perturbation caused by the seeds, markers and clips is significant at
close proximity and varies greatly on the material. Depending upon the treatment planning system
accuracy in predicting dose in inhomogeneous media, this effect may not be
fully observed.
An alternative method for beam output constancy
measurements
Dinko
Plenkovich, Roswell Park Cancer Institute, WCA Cancer Treatment Center,
Jamestown, NY
Purpose: After the completion of the absolute TG-51
calibration in water, measurements are, usually, taken in a plastic phantom,
and the beam-output-constancy coefficients are calculated. It is important to perform these measurements
in plastic immediately after the absolute TG-51 calibration. An alternative method is proposed, which
does not require any measurements after the completion of the absolute TG-51
calibration.
Method and Materials: The dose per monitor unit can be expressed in
the form Dose/MU = coefficient * PTP *Mraw. The coefficients, for various photon and
electron energies, are calculated from the TG-51 worksheets. For the constancy measurement of the beam
output, the same ionization chamber, cable, electrometer, water phantom, and
setup are used as for the absolute TG-51 calibration. Only the temperature inside the ionization
chamber, the atmospheric pressure, and the collected electric charge, Mraw,
for the polarity of the ionization chamber ADCL calibration, need to be
measured. For each of the photon and
electron energies, the ionization chamber is placed at the same depth, in
water, as during the absolute TG-51 calibration.
Results: If one has a water
phantom in which the depth of the ionization chamber in water can be controlled
from the treatment unit console, the measurement time is shorter than with the
plastic phantom, whose slabs have to be rearranged for different photon and
electron energies. When performing the
next TG-51 calibration, the newly measured beam output can be, easily, compared
with the output calculated using the previously calculated
beam-output-constancy coefficients, without the need to perform any measurement
in plastic.
Conclusion: The accuracy of the beam-output-constancy
measurement is higher in the water phantom because the conclusions do not need
to be inferred from water to plastic during the determination of the
beam-output-constancy coefficients and back from plastic to water during the
interpretation of the output-constancy results.