KEYWORDS: Monte Carlo methods, Computer simulations, Switches, Picture Archiving and Communication System, Particles, Medicine, Atrial fibrillation, Operating systems, Parallel computing, Computing systems
The Monte Carlo (MC) technique has been widely used as the gold standard for interaction of radiation with matter in the fields of medical physics, radiation therapy, and nuclear medicine. However, MC simulation is time consuming and requires a lot of computational resources. Generally, a dedicated high performance computing cluster is use to improve efficiency, but it is costly and lacks of the ability to run routine errands in healthcare facilities. In this study, we proposed a method for rapid deployment of computing platform for MC simulation in the PACS environment using review workstations as computing nodes. The workstations were booted from the network and initialed a RAM disk as the boot sector. The simplified Linux operating system and the Monte Carlo N-Particle Transport Code Version 5 (MCNP5) were transferred from the DRBL (Diskless Remote Boot in Linux) server to each node automatically. The cluster computing environment can be established within four minutes. We compared a commercially available dedicated cluster with the DRBL cluster. The results showed that the commercial cluster had a slightly higher acceleration factor than the DRBL cluster. The simulation time of the commercial and the DRBL clusters for 2×108 particle histories was 37,151 and 40,021 sec, respectively. When the number of rendezvous increased to 20, the maximum time differences between both clusters were 95 and 85 sec for the megabit and the gigabit switches. We conclude that the DRBL cluster can be quickly deployed to the non-workloaded review workstations in the PACS. Thus, the MC technique could be broadly used to enhance the research capability of radiological sciences in healthcare facilities.
Computed tomography (CT) has become a popular tool in radiologic diagnosis due to the ability of obtaining highresolution
anatomical images. However, radiation doses to patients are substantial and can increase the risk of cancer
incidence. Although lowering the tube current is a direct way to reduce absorbed doses, insufficient photon numbers can
cause severe quantum mottle and subsequently degrade the diagnostic value of CT images. In this study, we proposed an
algorithm for noise reduction of low-dose computed tomography (LDCT) based on the multiresolution total variation
minimization (MRTV) method. The discrete wavelet transform was used to decompose the CT image into high- and lowfrequency
wavelet coefficients. The total variation minimization with suitable tuning parameters was then applied to
reduce the variance among the wavelet coefficients. The noise-reduced image was reconstructed by the inverse wavelet
transform. The results of the Shepp-Logan phantom added with Gaussian white noise showed that the noise was
eliminated effectively and the SNR in the three compartments was increased from 2.04, 20.69 and 0.09 to 19.45, 187.77
and 0.27, respectively. In the CT image of the water phantom acquired with 50-mAs tube currents, the MRTV improved
the smoothness of the water compartment. The average SNR was increased from 0.14 to 0.98, which is even better than
the CT image acquired by 200 mAs. In the clinical head CT image with a tube current of 9.12 mAs, the MRTV
successfully removed the severe noise in the parenchyma, and SNR was increased from 0.982 to 3.452 in average. In
addition, the details of the septal structure of the sinus cavity were maintained. We conclude that the MRTV approach
can effectively reduce the image noise caused by the tube current insufficiency, and thereby could improve the
diagnostic value of LDCT images.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.