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We aimed to evaluate dosimetrically the effect of 6 MV, 10 MV and dual 6 and 10 MV photon beam energies on the liver of most cancers using steep and shoot IMRT methods, and we investigate a few important parameters, including dose, conformity index (CI) and homogeneity index (HI). The beams were arranged based on different angles. The same optimization constraints were applied for each energy planning and all other parameters, such as number of beams and beam angles, were kept constant.

The dose-volume histograms (DVHs) for the 6 MV, 10 MV and dual energy plans were compared for the planning target volume (PTV) and organs at risk (OAR). Twenty-eight cases ($n=28$) of liver SBRT patients formerly handled the use of steep and shoot IMRT techniques. Three plans with identical beam geometries were created using 6 MV, 10 MV and dual energy. In the central axis, the powerful intensity from each beam was calculated, and the values were averaged.

The static leaf sequencing (SLS) problem arises in radiation therapy for cancer treatments, aiming to accomplish the delivery of a radiation prescription to a target tumor in the minimum amount of delivery time. Geometrically, the SLS problem can be formulated as a 3-D partition problem for which the 2-D problem of partitioning a polygonal domain (possibly with holes) into a minimum set of monotone polygons is a special case. In this paper, we present new geometric algorithms for a basic case of the 3-D SLS problem (which is also of clinical value) and for the general 3-D SLS problem. Our basic 3-D SLS algorithm, based on new geometric observations, produces guaranteed optimal quality solutions using O(1) Steiner points in polynomial time; the previously best known basic 3-D SLS algorithm gives optimal outputs only for the case without considering any Steiner points, and its time bound involves a multiplicative factor of a factorial function of the input. Our general 3-D SLS algorithm is based on our basic 3-D SLS algorithm and a polynomial time algorithm for partitioning a polygonal domain (possibly with holes) into a minimum set of x-monotone polygons, and has a fast running time. Experiments of our SLS algorithms and software in clinical settings have shown substantial improvements over the current most popular commercial treatment planning system and the most well-known SLS algorithm in medical literature. The radiotherapy plans produced by our software not only take significantly shorter delivery times, but also have a much better treatment quality. This proves the feasibility of our software and has led to its clinical applications at the Department of Radiation Oncology at the University of Maryland Medical Center. Some of our techniques and geometric procedures (e.g., for partitioning a polygonal domain into a minimum set of x-monotone polygons) are interesting in their own right.

The 3-D static leaf sequencing (SLS) problem arises in radiation therapy for cancer treatments, aiming to deliver a prescribed radiation dose to a target tumor accurately and efficiently. The treatment time and machine delivery error are two crucial factors to the solution (i.e., a treatment plan) for the SLS problem. In this paper, we prove that the 3-D SLS problem is NP-hard, and present the first ever algorithm for the 3-D SLS problem that can determine a tradeoff between the treatment time and machine delivery error (also called the "tongue-and-groove" error in medical literature). Our new 3-D SLS algorithm with error control gives the users (e.g., physicians) the option of specifying a machine delivery error bound, and subject to the given error bound, the algorithm computes a treatment plan with the minimum treatment time. We formulate the SLS problem with error control as computing a k-weight shortest path in a directed graph and build the graph by computing g-matchings and minimum cost flows. Further, we extend our 3-D SLS algorithm to all the popular radiotherapy machine models with different constraints. In our extensions, we model the SLS problems for some of the radiotherapy systems as computing a minimum g-path cover of a directed acyclic graph. We implemented our new 3-D SLS algorithm suite and conducted an extensive comparison study with commercial planning systems and well-known algorithms in medical literature. Some of our experimental results based on real medical data are presented.

In this paper, we study an interesting matrix decomposition problem that seeks to decompose a "complicated" matrix into two "simpler" matrices while minimizing the sum of the horizontal complexity of the first sub-matrix and the vertical complexity of the second sub-matrix. The matrix decomposition problem is crucial for improving the "step-and-shoot" delivery efficiency in Intensity-Modulated Radiation Therapy, which aims to deliver a highly conformal radiation dose to a target tumor while sparing the surrounding normal tissues. Our algorithm is based on a non-trivial graph construction scheme, which enables us to formulate the decomposition problem as computing a minimum s-t cut in a 3-D geometric multi-pillar graph. Experiments on randomly generated intensity map matrices and on clinical data demonstrated the efficacy of our algorithm.

NRGene delivers first-ever food potato genomes.

CMC Biologics announces development and manufacturing agreement with Harpoon Therapeutics.

Typhoid vaccine prequalified.

Clearbridge BioMedics’ ClearCell FX1 system achieves U.S. FDA listing.

Singapore eDevelopment names Dr Roscoe Moore as senior scientific adviser to its biomedical arm.

Varian Halcyon treatment system receives Taiwan FDA approval.

Cancer Research Institute and Canadian Cancer Trials Group Announce Strategic Collaboration.

AGC Bioscience, Biomeva, and CMC Biologics to provide services under the brand AGC Biologics.

Illumina Launches iSeq 100 Sequencing System.

iGENE Laboratory granted licence by MOH to perform non-invasive prenatal test in Singapore.

Clarivate Analytics appoints new president for life sciences division.

Watsons partners with ChromaDex, to launch TRU NIAGEN in Singapore.

Colorcon, Inc. transforms sugar coating process with new Opadry System.

GSK Consumer Healthcare appoints Filippo Lanzi as head for Asia Pacific.

Chugai obtains approval for TECENTRIQ for treatment of unresectable, advanced or recurrent non-small cell lung cancer.

Historic deal signed between Panacea Biotec and Serum Institute of India.

me+ to partner Singapore Clinical Research Institute on new innovative healthcare solutions.

It is important to deliver radiation to treatment targets with accuracy. Typically, patients are positioned using marks on the surface of the skin. However, without imaging procedures, there is no information about the location of mobile internal organs and targets. The use of implanted radiopaque markers can help localize internal target organs using imaging modalities. Quality assurance procedures have been performed on commercially available spiral gold markers to determine their location and image quality. The results obtained from different, least essential imaging modalities employed in radiation therapy showed that these markers are not as clearly visible on radiographs as compared to the modalities with electronic output formats. The image quality was also poorer on megavoltage as compared to kilovoltage X-ray imaging modalities.

The goal of intensity-modulated radiation therapy (IMRT) is to deliver a uniform dose to the tumor with minimal margins around the target, in order to increase local control of the disease while reducing secondary effects. The research performed in this work has shown the potential usefulness of the Fricke-gel dosimeter as a quality assurance (QA) tool to verify IMRT treatments produced by inverse treatment planning. First, the 3D integrating Fricke-gel dosimeter was successfully compared to an accepted dosimetric tool. It was then used to measure relative 3D dose distributions of simple treatment plans with multiple square or rectangular fields and specific inverse-planned IMRT treatment plans. By combining the CT anatomical information and the plan contours with the gel-measured data, it was possible to display the contours on the measured dose and the measured isodose lines on the CT, in addition to measuring dose-volume histograms (DVH) for the plans. This demonstrated the usefulness of the gel dosimeter as a QA tool for IMRT and inverse planning.

This study aimed to investigate the dosimetric characteristics of intensity-modulated radiation therapy (IMRT) and RapidArc therapy by using 3D N-isopropylacrylamide (NIPAM) polymer gel. Optical computed tomography, specifically OCTOPUSTM-10X fast optical computed tomography scanner, was used as a readout tool. Two cylindrical acrylic phantoms (10 cm in diameter, 10 cm in height, and 3 mm in thickness) were filled with NIPAM gel and used for IMRT and RapidArc irradiation by using the Clinac iX treatment machine. The irradiation energies for IMRT and RapidArc® were set as 6 MV photons, but their irradiation angles and dose rates differed during irradiation. The irradiation angles of IMRT were 120°, 155°, 180°, 215°, and 245°, and the dose rate was fixed at 400 cGy/min. RapidArc® rotated continuously during irradiation, and the dose rate varied from 330 cGy/min to 400 cGy/min. The pass rates were 98.02% and 97.48% for IMRT and RapidArc®, respectively, and the rejected area appeared at the edge of the irradiated region. The isodose lines of IMRT and RapidArc® were consistent with those of TPS in most regions. Scattering and edge enhancement effects are main factors that cause dose inaccuracy in the edge region and reduced pass rates. Considering dose rate dependence, we used variable dose rates during irradiation with RapidArc®. Results showed that the dose distribution of NIPAM gel was consistent with that of TPS. The pass rates were also the same for IMRT and RapidArc® irradiation. This study proposes a preliminary profile of dosimetric characteristics of IMRT and RapidArc® by using a NIPAM gel dosimeter.