bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extraction of tube current values from DICOM CT images for patient dose estimation
Authors: Lin Pei‐Jan Paul , Kubo Takeshi , Krishnapillai Rajeev 
Published: June 2010

PurposeWhen CT examinations are conducted with automatic mA modulation (‐axis modulation), the tube current (mA) may vary from one CT slice to next, i.e., mA is no longer a fixed constant. Hence, patient dose calculation is no longer a straightforward process. The purpose of this article is to show how the mA information may be extracted from DICOM CT images without having to manually read off “mA values” from the displayed images one at a time.MethodsA statistical programming language called “R,” which is capable of reading DICOM files, is employed to extract the mA values from a series of DICOM CT images. This task is carried out with a “script” designed to read the mA values from the DICOM CT images and generate a file in “delimited ASCII” format. This file can be imported into a spreadsheet program such as Excel (a Microsoft spreadsheet program) for further processing, calculation, and chart production. A CT examination of the chest was selected to carry out this operation for demonstration purposes.ResultsThe “script” generated a delimited ASCII “file” which is a two column data sheet with the slice location and its corresponding mA values. After the file is imported into Excel for calculation, and with other pertinent scan parameters, the average mA can now be plugged into a CT dosimetry calculation program such as ImPACT for calculation of CTDIw, CTDIvol, dose‐length‐product, and critical organ doses. Furthermore, a graphical presentation of the “mA” vs slice location can be produced with Excel. The chart generated by Excel shows the variation in tube current as a function of slice location. The area under the mA curve is equal to a rectangle of . Here, the distance is the range covered by the CT scan.ConclusionsThe script that the authors have written is able to extract mA values from DICOM CT images, generating a delimited ASCII file for further processing with Microsoft Excel spreadsheet program. After the DICOM images are imported into a personal computer, this semiautomated process of extracting mA values enabled the authors to perform dose calculation for patients undergoing CT examination scanned with automatic mA modulation control.
Determination of exit skin dose for intracavitary accelerated partial breast irradiation with thermoluminescent dosimeters
Authors: Raffi Julie A. , Davis Stephen D. , Hammer Cliff G. , Micka John A. , Kunugi Keith A. , Musgrove Jana E. , Winston John W. , Ricci‐Ott Terresa J. , DeWerd Larry A. 
Published: June 2010

PurposeIntracavitary accelerated partial breast irradiation (APBI) has become a popular treatment for early stage breast cancer in recent years due to its shortened course of treatment and simplified treatment planning compared to traditional external beam breast conservation therapy. However, the exit dose to the skin is a major concern and can be a limiting factor for these treatments. Most treatment planning systems (TPSs) currently used for high dose‐rate (HDR) brachytherapy overestimate the exit skin dose because they assume a homogeneous water medium and do not account for finite patient dimensions. The purpose of this work was to quantify the TPS overestimation of the exit skin dose for a group of patients and several phantom configurations.MethodsThe TPS calculated skin dose for 59 HDR APBI patients was compared to the skin dose measured with LiF:Mg,Ti thermoluminescent dosimeters (TLDs). Additionally, the TPS calculated dose was compared to the TLD measured dose and the Monte Carlo (MC) calculated dose for eight phantom configurations. Four of the phantom configurations simulated treatment conditions with no scattering material beyond the point of measurement and the other four configurations simulated the homogeneous scattering conditions assumed by the TPS. Since the calibration TLDs for this work were irradiated with and the experimental irradiations were performed with , experiments were performed to determine the intrinsic energy dependence of the TLDs. Correction factors that relate the dose at the point of measurement (center of TLD) to the dose at the point of interest (basal skin layer) were also determined and applied for each irradiation geometry.ResultsThe TLD intrinsic energy dependence for relative to was . The TPS overestimated the exit skin dose by an average of 16% for the group of 59 patients studied, and by 9%–15% for the four phantom setups simulating treatment conditions. For the four phantom setups simulating the conditions assumed by the TPS, the TPS calculated dose agreed well with the TLD and MC results (within 3% and 1%, respectively). The inverse square geometry correction factor ranged from 1.023 to 1.042, and an additional correction factor of 0.978 was applied to account for the lack of charged particle equilibrium in the TLD and basal skin layer.ConclusionsTPS calculations that assume a homogeneous water medium overestimate the exit skin dose for intracavitary APBI treatments. It is important to determine the actual skin dose received during intracavitary APBI to determine the skin dose‐response relationship and establish dose limits for optimal skin sparing. This study has demonstrated that TLDs can measure the skin dose with an expanded uncertainty of 5.6% when the proper corrections are applied.
A randomization approach to handling data scaling in nuclear medicine
Authors: Bai Chuanyong , Conwell Richard , Kindem Joel 
Published: June 2010

PurposeIn medical imaging, data scaling is sometimes desired to handle the system complexity, such as uniformity calibration. Since the data are usually saved in short integer, conventional data scaling will first scale the data in floating point format and then truncate or round the floating point data to short integer data. For example, when using truncation, scaling of 9 by 1.1 results in 9 and scaling of 10 by 1.1 results in 11. When the count level is low, such scaling may change the local data distribution and affect the intended application of the data.MethodsIn this work, the authors use an example gated cardiac SPECT study to illustrate the effect of conventional scaling by factors of 1.1 and 1.2. The authors then scaled the data with the same scaling factors using a randomization approach, in which a random number evenly distributed between 0 and 1 is generated to determine how the floating point data will be saved as short integer data. If the random number is between 0 and 0.9, then 9.9 will be saved as 10, otherwise 9. In other words, the floating point value 9.9 will be saved in short integer value as 10 with 90% probability or 9 with 10% probability. For statistical analysis of the performance, the authors applied the conventional approach with rounding and the randomization approach to 50 consecutive gated studies from a clinical site.ResultsFor the example study, the image reconstructed from the original data showed an apparent perfusion defect at the apex of the myocardium. The defect size was noticeably changed by scaling with 1.1 and 1.2 using the conventional approaches with truncation and rounding. Using the randomization approach, in contrast, the images from the scaled data appeared identical to the original image. Line profile analysis of the scaled data showed that the randomization approach introduced the least change to the data as compared to the conventional approaches. For the 50 gated data sets, significantly more studies showed quantitative differences between the original images and the images from the data scaled by 1.2 using the rounding approach than the randomization approach [46/50 (92%) versus 3/50 (6%), ]. Likewise, significantly more studies showed visually noticeable differences between the original images and the images from the data scaled by 1.2 using the rounding approach than randomization [29/50 (58%) versus 1/50 (2%), ].ConclusionsIn conclusion, the proposed randomization approach minimizes the scaling‐introduced local data change as compared to the conventional approaches. It is preferred for nuclear medicine data scaling.
Influence of beam efficiency through the patient‐specific collimator on secondary neutron dose equivalent in double scattering and uniform scanning modes of proton therapy
Authors: Hecksel D. , Anferov V. , Fitzek M. , Shahnazi K. 
Published: June 2010

PurposeConventional proton therapy facilities use double scattering nozzles, which are optimized for delivery of a few fixed field sizes. Similarly, uniform scanning nozzles are commissioned for a limited number of field sizes. However, cases invariably occur where the treatment field is significantly different from these fixed field sizes. The purpose of this work was to determine the impact of the radiation field conformity to the patient‐specific collimator on the secondary neutron dose equivalent.MethodsUsing a WENDI‐II neutron detector, the authors experimentally investigated how the neutron dose equivalent at a particular point of interest varied with different collimator sizes, while the beam spreading was kept constant. The measurements were performed for different modes of dose delivery in proton therapy, all of which are available at the Midwest Proton Radiotherapy Institute (MPRI): Double scattering, uniform scanning delivering rectangular fields, and uniform scanning delivering circular fields. The authors also studied how the neutron dose equivalent changes when one changes the amplitudes of the scanned field for a fixed collimator size.ResultsThe secondary neutron dose equivalent was found to decrease linearly with the collimator area for all methods of dose delivery. The relative values of the neutron dose equivalent for a collimator with a 5 cm diameter opening using 88 MeV protons were 1.0 for the double scattering field, 0.76 for rectangular uniform field, and 0.6 for the circular uniform field. Furthermore, when a single circle wobbling was optimized for delivery of a uniform field 5 cm in diameter, the secondary neutron dose equivalent was reduced by a factor of 6 compared to the double scattering nozzle. Additionally, when the collimator size was kept constant, the neutron dose equivalent at the given point of interest increased linearly with the area of the scanned proton beam.ConclusionsThe results of these experiments suggest that the patient‐specific collimator is a significant contributor to the secondary neutron dose equivalent to a distant organ at risk. Improving conformity of the radiation field to the patient‐specific collimator can significantly reduce secondary neutron dose equivalent to the patient. Therefore, it is important to increase the number of available generic field sizes in double scattering systems as well as in uniform scanning nozzles.
MapCHECK used for rotational IMRT measurements: Step‐and‐shoot, Tomotherapy, RapidArc
Authors: Jursinic Paul A. , Sharma Renu , Reuter Jim 
Published: June 2010

PurposeTo measure patient‐specific‐QA dose distributions with a 2D array of diodes, the MapCHECK, for the dose delivered, with step‐and‐shoot and rotational IMRT.MethodsTwo MapCHECKs were used that had different styles of diode connection. These MapCHECKs were used in their original manufactured configuration and in a modified configuration. The modification made in the clinic consists of filling air gaps with sheets of Lucite that had custom‐machined slots for the diodes and by adding pieces of copper to offset the intrinsic asymmetry of the diodes. The MapCHECKs were housed in a tight‐fitting phantom fabricated from solid water. Measurements were made on IMRT treatment plans delivered with Varian linear accelerators with step‐and‐shoot and RapidArc methods, and a TomoTherapy machine with helical delivery. Patient plans and QA plans were developed with the XiO, Eclipse, and TomoTherapy planning systems. All MapCHECK data were analyzed with its commercially available software.ResultsKilovoltage CT imaging of the MapCHECK in its phantom has streak artifacts from high atomic number components. These artifacts must be corrected in order to obtain accurate calculation of dose. The original MapCHECK is found to have an angular dependence of ±20%. A modification of the MapCHECK has been made that reduces the angular dependence to ±2%. Proper compensation for attenuation by the treatment couch is also necessary for accurate results. The modified MapCHECK has been successfully used for doing patient‐specific QA for IMRT treatments delivered with step‐and‐shoot, TomoTherapy, and RapidArc methods. Treatment plans that require large amounts of fluence from the 90° and 270° directions have significantly better QA measurements when made with modified MapCHECKs.ConclusionsWhen properly modified, the MapCHECK response becomes isotropic. It can then be used for patient‐specific QA measurements for IMRT treatments delivered with step‐and‐shoot and rotational techniques such as helical Tomotherapy and RapidArc.
kVCT, MVCT, and hybrid CT image studies—Treatment planning and dose delivery equivalence on helical tomotherapy
Authors: Martin Spencer , Yartsev Slav 
Published: June 2010

PurposeTo determine the equivalence of radiation therapy treatment planning and delivery for various imaging options on helical tomotherapy.MethodsSeven treatment plans using identical anatomy and planning parameters were created based on the following CT studies: Standard kilovoltage CT (kVCT); 2, 4, and 6 mm spacing megavoltage CT (MVCT); and 2, 4, and 6 mm hybrid MVCT/kVCT studies. In addition, two kVCT based plans were created to explore the effect of the choice of dose calculation grid for optimization. Calculated and measured dose distributions were compared via volumetric and dosimetric analysis at the planning stage, point dose measurements with ion chamber, along with EDR2 film data for gamma function analysis for distance to agreement of 3 mm and dose differences of 3%, 5%, and 7% using both the commercially available “cheese” phantom and the new QUASAR Verification (QVer) phantom.ResultsPlans created for each imaging option showed residual error increasing as image slice spacing increased and critical structure size decreased. With the exception of the low dose area in hybrid studies, point dose measurements were within the calculated/measured dose acceptance criteria of 5% on both the QVer and cheese phantoms. Gamma analysis for the original kVCT plan delivery showed an average of and of dose pixels passing kVCT study treatment and delivery quality assurance procedures, respectively. The QVer phantom allows for delivery quality assurance with simultaneous use of two films and more convenient gamma function assessment but shows some measurement discrepancy up to 10% compared to the cheese phantom.ConclusionsThe kVCT, MVCT, and kVCT/MVCT hybrid studies showed considerable agreement at both planning and delivery stages. The choice of calculation grid is more important when dealing with smaller anatomical structures.
Microwaves create larger ablations than radiofrequency when controlled for power in ex vivo tissue
Authors: Andreano A. , Huang Yu , Meloni M. Franca , Lee Fred T. , Brace Christopher 
Published: June 2010

PurposeTo compare ablation zones created with equal amounts of 2.45 GHz microwave and 480 kHz radiofrequency (RF) energy inex vivo liver and lung.MethodsA total of 38 ablations were performed inex vivo liver and lung for 10 min each. Nineteen RF ablations (nine liver, ten lung) were performed with a 480 kHz system (200 W max, impedance‐based pulsing) and cooled electrode while measuring the average RF power applied. Nineteen microwave ablations (nine liver, ten lung) were then created using a cooled triaxial antenna to deliver 2.45 GHz at the same power level as in RF experiments. Ablation zones were then sectioned and measured for minimum, maximum and mean diameters, and circularity. Measurements were compared using ‐tests, with indicating statistical significance.ResultsMean diameters of microwave ablations were greater than RF ablations in both liver and lung ( vs in liver; vs in lungs; all comparisons). There was no significant difference in the mean power applied during microwave or RF ablations in either organ ( vs in liver, ; vs in lung, ).ConclusionsUsing a single cooled applicator, microwave energy at 2.45 GHz produces larger ablations than an equivalent amount of 480 kHz RF energy in normal liver and lung. This was more apparent in lung, likely due to the high baseline impedance which limits RF, but not microwave power delivery.
Investigations of the spin Hamiltonian parameters for the cubic Mn2+ centers in ZnX (X = S, Se, Te) and CdTe
Authors: Wang Xue-Feng , Wu Shao-Yi , Li Li-Li , Zhang Shan-Xiang 
Published: June 2010

The spin Hamiltonian parameters (g factors and the hyperfine structure constants) for the cubic Mn2+ centers in ZnX (X = S, Se, Te) and CdTe are investigated theoretically using the perturbation formulas of these parameters for a tetrahedral 3d5 cluster containing both the crystal-field and charge-transfer contributions. The relevant molecular orbital coefficients are uniformly determined from the cluster approach, and the calculated spin Hamiltonian parameters are in good agreement with the observed values. The g-shifts of the g factors related to the pure spin value gs (≈ 2.0023) arising from the charge transfer contributions are opposite (positive) in sign and much larger in magnitude than those from the crystal field contributions. On the other hand, the contributions from the charge-transfer mechanism to the hyperfine structure constants are the same in sign and about 20%–30% in magnitude of those from the crystal-field mechanism. The importance of the charge transfer contributions increases significantly with the increase of the covalency and the spin–orbit coupling coefficient of the ligand, i.e., S2− < Se2− < Te2−.
High VEGFC expression is associated with unique gene expression profiles and predicts adverse prognosis in pediatric and adult acute myeloid leukemia
Authors: de Jonge Hendrik J. M. , Valk Peter J. M. , Veeger Nic J. G. M. , ter Elst Arja , den Boer Monique L. , Cloos Jacqueline , Haas Valérie de , van den Heuvel-Eibrink Marry M. , Kaspers Gertjan J. L. , Zwaan Christian M. , Kamps Willem A. , Löwenberg Bob , de Bont Eveline S. J. M. 
Published: June 2010

AbstractHigh VEGFC mRNA expression of acute myeloid leukemia (AML) blasts is related to increased in vitro and in vivo drug resistance. Prognostic significance of VEGFC on long-term outcome and its associated gene expression profiles remain to be defined. We studied effect of VEGFC on treatment outcome and investigated gene expression profiles associated with VEGFC using microarray data of 525 adult and 100 pediatric patients with AML. High VEGFC expression appeared strongly associated with reduced complete remission rate (P = .004), reduced overall and event-free survival (OS and EFS) in adult AML (P = .002 and P < .001, respectively). Multivariable analysis established high VEGFC as prognostic indicator independent of cytogenetic risk, FLT3-ITD, NPM1, CEBPA, age, and white blood cell count (P = .038 for OS; P = .006 for EFS). Also, in pediatric AML high VEGFC was related to reduced OS (P = .041). A unique series of differentially expressed genes was identified that distinguished AML with high VEGFC from AML with low VEGFC, that is, 331 up-regulated genes (representative of proliferation, vascular endothelial growth factor receptor activity, signal transduction) and 44 down-regulated genes (eg, related to apoptosis) consistent with a role in enhanced chemoresistance. In conclusion, high VEGFC predicts adverse long-term prognosis and provides prognostic information in addition to well-known prognostic factors.
Immunophenotypic features of tumor infiltrating lymphocytes from mammary carcinomas in female dogs associated with prognostic factors and survival rates
Authors: Estrela-Lima Alessandra , Araújo Márcio SS , Costa-Neto João M , Teixeira-Carvalho Andréa , Barrouin-Melo Stella M , Cardoso Sergio V , Martins-Filho Olindo A , Serakides Rogéria , Cassali Geovanni D 
Published: June 2010

AbstractBackgroundThe immune system plays an important role in the multifactorial biologic system during the development of neoplasias. However, the involvement of the inflammatory response in the promotion/control of malignant cells is still controversial, and the cell subsets and the mechanisms involved are poorly investigated. The goal of this study was to characterize the clinical-pathological status and the immunophenotyping profile of tumor infiltrating lymphocytes and their association with the animal survival rates in canine mammary carcinomas.MethodsFifty-one animals with mammary carcinomas, classified as carcinomas in mixed tumors-MC-BMT = 31 and carcinomas-MC = 20 were submitted to systematic clinical-pathological analysis (tumor size; presence of lymph node and pulmonary metastasis; clinical stage; histological grade; inflammatory distribution and intensity as well as the lymphocytic infiltrate intensity) and survival rates. Twenty-four animals (MC-BMT = 16 and MC = 8) were elected to the immunophenotypic study performed by flow cytometry.ResultsData analysis demonstrated that clinical stage II-IV and histological grade was I more frequent in MC-BMT as compared to MC. Univariate analysis demonstrated that the intensity of inflammation (moderate/intense) and the proportion of CD4+(≥ 66.7%) or CD8+T-cells (<33.3%) were not associated with worse survival rate. Multivariate analysis demonstrated that only lymphocytic infiltrate intensity ≥ 600 (P= 0.02) remained as independent prognostic factor. Despite the clinical manifestation, the lymphocytes represented the predominant cell type in the tumor infiltrate. The percentage of T-cells was higher in animals with MC-BMT without metastasis, while the percentage of B-lymphocytes was greater in animals with metastasized MC-BMT (P< 0.05). The relative percentage of CD4+T-cells was significantly greater in metastasized tumors (both MC-BMT and MC), (P< 0.05) while the proportion of CD8+T-cells was higher in MC-BMT without metastasis. Consequently, the CD4+/CD8+ratio was significantly increased in both groups with metastasis. Regardless of the tumor type, the animals with high proportions of CD4+and low CD8+T-cells had decreased survival rates.ConclusionThe intensity of lymphocytic infiltrate and probably the relative abundance of the CD4+and CD8+T-lymphocytes may represent important survival prognostic biomarkers for canine mammary carcinomas.