bluuebunny/crossref_metadata_2025_split huggingface dataset:
SWIMRT: A graphical user interface using the sliding window algorithm to construct a fluence map machine file
Authors: Chow James C.L. , Grigorov Grigor N. , Yazdani Nuri 
Published: February 2007

A custom‐made computer program, SWIMRT, to construct “multileaf collimator (MLC) machine” file for intensity‐modulated radiotherapy (IMRT) fluence maps was developed using MATLAB® and the sliding window algorithm. The user can either import a fluence map with a graphical file format created by an external treatment‐planning system such as or create his or her own fluence map using the matrix editor in the program. Through comprehensive calibrations of the dose and the dimension of the imported fluence field, the user can use associated image‐processing tools such as field resizing and edge trimming to modify the imported map. When the processed fluence map is suitable, a “MLC machine” file is generated for our Varian 21 EX linear accelerator with a 120‐leaf Millennium MLC. This machine file is transferred to the MLC console of the LINAC to control the continuous motions of the leaves during beam irradiation. An IMRT field is then irradiated with the 2D intensity profiles, and the irradiated profiles are compared to the imported or modified fluence map. This program was verified and tested using film dosimetry to address the following uncertainties: (1) the mechanical limitation due to the leaf width and maximum traveling speed, and (2) the dosimetric limitation due to the leaf leakage/transmission and penumbra effect. Because the fluence map can be edited, resized, and processed according to the requirement of a study, SWIMRT is essential in studying and investigating the IMRT technique using the sliding window algorithm. Using this program, future work on the algorithm may include redistributing the time space between segmental fields to enhance the fluence resolution, and readjusting the timing of each leaf during delivery to avoid small fields. Possible clinical utilities and examples for SWIMRT are given in this paper.PACS numbers: 87.53.Kn, 87.53.St, 87.53.Uv
Use of a multileaf collimator to increase the field width achievable with a dynamic wedge
Authors: Brezovich Ivan A. , Popple Richard A. , Duan Jun 
Published: February 2007

A method is proposed for generating dynamic wedges spanning the entire field width, defined as the collimator opening in the wedged direction, without changes to existing hardware. The technique approximates the fluence pattern of a dynamic wedge by sequentially closing the leaves of a 120‐leaf multileaf collimator (MLC). Closure times for the individual leaves were derived by extending the segmented treatment table of the dynamic wedge provided by the manufacturer of the linear accelerator. Using film dosimetry, beam properties of MLC wedges were compared to those of conventional dynamic and mechanical wedges. Profiles and isodose lines of the MLC wedge were almost identical to those of the dynamic wedge, and differed only modestly from the mechanical counterparts. Dose inhomogeneity due to the individually closing leaves was not significant. The high‐dose region at the junction between opposing MLC leaves, unavoidable when the field length (i.e., the opening of the collimator in the nonwedged direction) exceeds the maximum leaf extension of 15 cm, was feathered by moving leaf pairs after their closure for the remainder of the irradiation time. Combining the MLC wedge with a regular dynamic wedge to reduce the line of high dose under the leaf junction is under consideration.PACS number: 87.53.Mr
Out‐of‐field dosimetry measurements for a helical tomotherapy system
Authors: Ramsey Chester R. , Seibert Rebecca , Mahan Stephen L. , Desai Dharmin , Chase Daniel 
Published: February 2007

Helical tomotherapy is a rotational delivery technique that uses intensity‐modulated fan beams to deliver highly conformal intensity‐modulated radiation therapy (IMRT). The beam‐on time needed to deliver a given prescribed dose can be up to 15 times longer than that needed using conventional treatment delivery. As such, there is concern that this delivery technique has the potential to increase the whole body dose due to increased leakage. The purpose of this work is to directly measure out‐of‐field doses for a clinical tomotherapy system. Peripheral doses were measured in‐phantom using static fields and rotational intensity‐modulated delivery. In‐air scatter and leakage doses were also measured at multiple locations around the treatment room. At 20 cm, the tomotherapy peripheral dose dropped to 0.4% of the prescribed dose. Leakage accounted for 94% of the in‐air dose at distances greater than 60 cm from the machine's isocenter. The largest measured dose equivalent rate was Sv/s in the plane of gantry rotation due to head leakage and primary beam transmission through the system's beam stopper. The dose equivalent rate dropped to Sv/s at the end of the treatment couch. Even though helical tomotherapy treatment delivery requires beam‐on times that are 5 to 15 times longer than those used by conventional accelerators, the delivery system was designed to maximize shielding for radiation leakage. As such, the peripheral doses are equal to or less than the published peripheral doses for IMRT delivery on other linear accelerators. In addition, the shielding requirements are also similar to conventional linear accelerators.PACS number: 87.53.Dq
Study of the influence of phantom material and size on the calibration of ionization chambers in terms of absorbed dose to water
Authors: Arib Mehenna , Medjadj Toufik , Boudouma Youcef 
Published: February 2007

In the International Atomic Energy Agency's (IAEA) code of practice (TRS 398) and the American Association of Physicists in Medicine's dosimetry protocol (TG‐51), full‐scatter water phantoms are recommended for the determination of the absorbed dose for both photon and electron beams and, consequently, for the calibration of the user's ionization chambers. This procedure is applied in the Secondary Standard Dosimetry Laboratory, where the calibration is performed on a gamma beam, in comparison with reference chambers whose absorbed dose‐to‐water calibration coefficients, , are known. In this work, we present the results of the calibration of 10 Farmer‐like ionization chambers calibrated in three water phantoms (sizes , , and ) and two plastic phantoms (size ) polymethyl methacrlyate (PMMA) and polystyrene). Calibrations are performed by the substitution method using an ionization chamber whose has been supplied by the IAEA's reference laboratory. It is shown that the results, expressed as the percentage ratio of the calibration coefficient in a given phantom to that of the standard IAEA phantom, is less than 0.35% for all investigated chambers, and that the standard deviation of the mean of the calibration coefficients determined in all five phantoms is less than 0.06%, except for one nylon‐walled ionization chamber, where the observed 0.34% value could be explained by the hygroscopic properties of nylon. Furthermore, a chamber‐to‐chamber dependence of the calibration coefficient has been shown to vary by up to 2.8%. These results emphasize that the phantom dimensions and its material are not sensitive criteria for the calibration of cylindrical ionization chambers in terms of absorbed dose to water. The results also show that generic calibration coefficients could not be considered for a given type of chamber.PACS number: 87.53.Dq
Comparison of measured and computed portal dose for IMRT treatment
Authors: Cilla Savino , Viola Pietro , Azario Luigi , Grimaldi Luca , Craus Maurizio , D'Onofrio Guido , Fidanzio Andrea , Deodato Francesco , Macchia Gabriella , Digesù Cinzia , Morganti Alessio G. , Piermattei Angelo 
Published: February 2007

A new 2D array Seven 29™ model (PTW, Freiburg), equipped with 729 vented plane‐parallel ion chambers, projected for pretreatment verification of radiotherapy plans, was used as a detector for the transmitted or portal dose measurements below a Rando phantom. The dosimetric qualities of the 2D array make it attractive for measuring transmitted dose maps from step‐and‐shoot intensity‐modulated radiotherapy (IMRT). It is well known that for step‐and‐shoot IMRT beams that use a small number of monitor units (MUs) per sequence, the early and recent electronic portal imaging devices (EPIDs) present a different response at X‐ray start‐up that affects the accuracy of the measured transmitted dose. The comparison of portal doses measured to those calculated by a commercial treatment‐planning system (TPS) can verify correct dose delivery during treatment. This direct validation was tested by irradiating a simulated head tumor in a Rando anthropomorphic phantom by step‐and‐shoot IMRT beams. The absolute transmitted doses on a plane orthogonal to the beam central axis below the phantom were measured by the 2D array calibrated in terms of dose to water and compared with the computed portal dose extracted by custom software. In a previous paper, the comparison between the IMRT portal doses, computed by a commercial TPS and measured by a linear array that supplied a 1 mm spatial dose resolution, was carried out. The γ‐index analysis supplied an agreement of more than 95% of the dose point with acceptance criteria, in terms of dose difference, , and distance agreement, , equal to 4% and 4 mm, respectively. In this paper, we verify the possible use of the PTW 2D array for measurements of the transmitted doses during several fractions of head and neck tumor radiotherapy. There are two advantages in the use of this 2D array as a portal dose device for the IMRT quality assurance program: first is the ability to perform absolute dose comparisons for hundreds of measurement positions to verify the correct dose delivery in several fractions of the therapy; second is the efficiency in time to detect these kinds of dose distributions within the field of view area of the CT scanner.PACS number: 87.53.Xd
Dose modification factors for 192Ir high‐dose‐rate irradiation using Monte Carlo simulations
Authors: Kassas Bassel , Mourtada Firas , Horton John L. , Lane Richard G. , Buchholz Thomas A. , Strom Eric A. 
Published: February 2007

A recently introduced brachytherapy system for partial breast irradiation, MammoSite, consists of a balloon applicator filled with contrast solution and a catheter for insertion of an high‐dose‐rate (HDR) source. In using this system, the treatment dose is typically prescribed to be delivered 1 cm from the balloon's surface. Most treatment‐planning systems currently in use for brachytherapy procedures use water‐based dosimetry with no correction for heterogeneity. Therefore, these systems assume that full scatter exists regardless of the amount of tissue beyond the prescription line. This assumption might not be a reasonable one, especially when the tissue beyond the prescription line is thin. In such a case, the resulting limited scatter could cause an underdose to be delivered along the prescription line. We used Monte Carlo simulations to investigate how the thickness of the tissue between the surface of the balloon and the skin or lung affected the treatment dose delivery. Calculations were based on a spherical water phantom with a diameter of 30 cm and balloons with diameters of 4 cm, 5 cm, and 6 cm. The dose modification factor is defined as the ratio of the dose rate at the typical prescription distance of 1 cm from the balloon's surface with full scatter obtained using the water phantom to the dose rate with a finite tissue thickness (from 0 cm to 10 cm) beyond the prescription line. The dose modification factor was found to be dependent on the balloon diameter and was 1.098 for the 4‐cm balloon and 1.132 for the 6‐cm balloon with no tissue beyond the prescription distance at the breast–skin interface. The dose modification factor at the breast–lung interface was 1.067 for the 4‐cm balloon and 1.096 for the 6‐cm balloon. Even 5 cm of tissue beyond the prescription distance could not result in full scatter. Thus, we found that considering the effect of diminished scatter is important to accurate dosimetry. Not accounting for the dose modification factor may result in delivering a lower dose than is prescribed.PACS number: 87.53.Jw
Book Review
Authors: Smith René J. 
Published: February 2007

Editors Note: This book is written in Spanish and the review is given in both English and Spanish. Both reviews were written by the same individual and essentially have the same content.Code of Practice for Quality Control of Treatment Planning Systems (TPS) in Radiation Therapy, by José Miguel Delgado Rodríguez, Feliciano García Vicente, Esther Millán Cebrián. Sociedad Española de Física Médica. Ramírez de Arellano Editores, S. L. 2005, Madrid, Spain; available. secretaria@sefm.es, 50εProtocolo para Control de Calidad en Sistemas de Planificación de Terapia con Radiaciones Ionizantes, por José Miguel Delgado Rodríguez, Feliciano García Vicente, Esther Millán Cebrián. Sociedad Española de Física Médica. Ramírez de Arellano Editores, S. L. 2005, Madrid, Spain.secretaria@sefm.es, 50ε
Expression of the Human Hepatitis B Virus Large Surface Antigen Gene in Transgenic Tomato Plants
Authors: Lou Xiao-Ming , Yao Quan-Hong , Zhang Zhen , Peng Ri-He , Xiong Ai-Sheng , Wang Hua-Kun 
Published: February 2007

ABSTRACT
The original hepatitis B virus (HBV) large surface antigen gene was synthesized. In order to optimize the expression of this gene in tomato plants, the tobacco pathogenesis-related protein S signal peptide was fused to the 5′ end of the modified gene and the sequence encoding amino acids S, E, K, D, E, and L was placed at the 3′ end. The gene encoding the modified HBV large surface antigen under the control of a fruit-specific promoter was constructed and expressed in transgenic tomato plants. The expression of the antigen from transgenic plants was confirmed by PCR and reverse transcriptase PCR. Enzyme-linked immunoassays using a monoclonal antibody directed against human serum-derived HBsAg revealed that the maximal level of HBsAg was about 0.02% of the soluble protein in transgenic tomato fruit. The amount of HBsAg in mature fruits was found to be 65- to 171-fold larger than in small or medium fruits and leaf tissues. Examination of transgenic plant samples by transmission electron microscopy proved that HBsAg had been expressed and had accumulated. The HBsAg protein was capable of assembling into capsomers and virus-like particles. To our knowledge, this is the first time the HBV large surface antigen has been expressed in plants. This work suggests the possibility of producing a new alternative vaccine for human HBV.
Long-Lasting Protective Immune Response to the 19-Kilodalton Carboxy-Terminal Fragment ofPlasmodium yoeliiMerozoite Surface Protein 1 in Mice
Authors: Jeamwattanalert Pimmada , Mahakunkijcharoen Yuvadee , Kittigul Leera , Mahannop Pakpimol , Pichyangkul Sathit , Hirunpetcharat Chakrit 
Published: February 2007

ABSTRACTMerozoite surface protein 1 (MSP1) is the major protein on the surface of the plasmodial merozoite, and its carboxy terminus, the 19-kDa fragment (MSP119), is highly conserved and effective in induction of a protective immune response against malaria parasite infection in mice and monkeys. However, the duration of the immune response has not been elucidated. As such, we immunized BALB/c mice with a standard four-dose injection of recombinantPlasmodium yoeliiMSP119formulated with Montanide ISA51 and CpG oligodeoxynucleotide (ODN) and monitored the MSP119-specific antibody levels for up to 12 months. The antibody titers persisted constantly over the period of time without significant waning, in contrast to the antibody levels induced by immunization with Freund's adjuvant, where the antibody levels gradually declined to significantly lower levels 12 months after immunization. Investigation of immunoglobulin G (IgG) subclass longevity revealed that only the IgG1 antibody level (Th2 type-driven response) decreased significantly by 6 months, while the IgG2a antibody level (Th1 type-driven response) did not change over the 12 months after immunization, but the boosting effect was seen in the IgG1 antibody responses but not in the IgG2a antibody responses. After challenge infection, all immunized mice survived with negligibly patent parasitemia. These findings suggest that protective immune responses to MSP119following immunization using oil-based Montanide ISA51 and CpG ODN as an adjuvant are very long-lasting and encourage clinical trials for malaria vaccine development.
Use of a Novel Chimeric Mouse Model with a Functionally Active Human Immune System To Study Human Immunodeficiency Virus Type 1 Infection
Authors: An Dong Sung , Poon Betty , Fang Raphael Ho Tsong , Weijer Kees , Blom Bianca , Spits Hergen , Chen Irvin S. Y. , Uittenbogaart Christel H. 
Published: February 2007

ABSTRACT

The goal of this study was to develop a small-animal model to study human immunodeficiency virus type 1 (HIV-1) pathogenesis in blood and primary and secondary lymphoid organs. Rag2
−/−
γ
c
−/−
mice that are neonatally injected with human CD34
+
cells develop a functional human immune system (HIS), with human hematopoietic cells being found in the thymuses, peripheral blood, spleens, and bone marrow of the animals (hereafter these animals are referred to as HIS-Rag2
−/−
γ
c
−/−
mice). HIS-Rag2
−/−
γ
c
−/−
mice were infected with small amounts of CCR5-tropic HIV-1. Viral replication and immunophenotypic changes in the human cells in peripheral blood and lymphoid organs were examined. The productive infection of human cells in peripheral blood, thymus and spleen tissue, and bone marrow was detected. Ratios of CD4
+
T cells to CD8
+
T cells in the infected animals declined. Although no specific anti-HIV-1 immune responses were detected, immunoglobulin M (IgM) and IgG antibodies to an unidentified fetal calf serum protein present in the virus preparation were found in the inoculated animals. Thus, we have shown that the HIS-Rag2
−/−
γ
c
−/−
mouse model can be used for infection with low doses of CCR5-tropic HIV-1, which is most commonly transmitted during primary infections. HIS-Rag2
−/−
γ
c
−/−
mice can serve as a small-animal model for investigating HIV-1 pathogenesis and testing potential HIV-1 therapies, and studies with this model may replace some long and costly studies with nonhuman primates.
Comparative Evaluation of Enzyme-Linked Immunosorbent Assays Based on Crude and Recombinant Leishmanial Antigens for Serodiagnosis of Symptomatic and Asymptomatic
Leishmania infantum
Visceral Infections in Dogs
Authors: Porrozzi Renato , Santos da Costa Marcos V. , Teva Antonio , Falqueto Aloísio , Ferreira Adelson L. , dos Santos Claudiney D. , Fernandes Ana Paula , Gazzinelli Ricardo T. , Campos-Neto Antonio , Grimaldi Gabriel 
Published: February 2007

ABSTRACT

The diagnosis of visceral leishmaniasis remains difficult in rural areas where the disease is endemic, and serologic methods still need assessment, as they are not very sensitive for the detection of asymptomatic infectious dogs. Here we present data on the development of enzyme-linked immunosorbent assay (ELISA)-based methods for the detection of antibodies against recombinant leishmanial antigens (namely, the recombinant K26 [rK26] and rK39 antigens from
Leishmania infantum
and the rA2 protein from
Leishmania donovani
) in comparison to ELISAs employing crude soluble antigen (CSA). The assays utilized sera from known negative controls (
n
= 25) and clinically asymptomatic (
n
= 50) and symptomatic (
n
= 50) dogs with confirmed
L. infantum
infections. Additional studies were also done using sera from animals harboring other infections (
n
= 14) for the evaluation of cross-reactivity. Our study indicated that rK26 and rK39 used in ELISAs provided very high sensitivities for the detection of symptomatic dogs (94% and 100%, respectively), followed by CSA (88%) and rA2 (70%). Conversely, rA2 was more sensitive for asymptomatic dogs (88%) than rK39 and rK26 (both 66%) and CSA (30%). Some cross-reactivity in sera from dogs with other infections (
Leishmania braziliensis
and
Leptospira interrogans
) was identified, but the rA2 protein provided the greatest specificity (98%). Data further indicate that all three recombinant proteins must be used in parallel to detect essentially all infected dogs. Efforts should be made to develop a cheap and reliable serologic test based on epitope selection from these diagnostic markers for the sensitive detection of
L. infantum
-infected dogs.
Detection of Human Papillomavirus Type 16-Specific T Lymphocytes by a Recombinant Vaccinia Virus-Based Enzyme-Linked Immunospot Assay
Authors: Kim Kevin H. , Greenfield William , Shotts Ezekiel , Nakagawa Mayumi 
Published: February 2007

ABSTRACT

Cell-mediated immunity, particularly that induced by T cells, is thought to have a key role in controlling infection. The enzyme-linked immunospot (ELISPOT) assay has been successfully adapted to detect T-cell immune response to a variety of pathogens. However, it still remains a challenge to detect antigen-specific T cells when the numbers of circulating cells are low, such as in a local cervical infection caused by genital human papillomavirus (HPV). The goal of this study was to develop a protocol for enhanced detection of HPV-specific CD8
+
T cells by examining a number of the variables involved in performing an ELISPOT assay. Since blood samples consistently positive for HPV-specific T cells are difficult to obtain, previously described human papillomavirus type 16 (HPV16) E6 52-61 (FAFRDLCIVY)-specific T-cell clone cells (13) seeded in peripheral blood mononuclear cells from an HLA-B57-positive blood donor were used. The variables examined were the amounts of primary and secondary anti-gamma interferon antibodies, amounts of antigen-presenting monocytes and recombinant vaccinia virus expressing the HPV16 E6 protein, and amounts of exogenous cytokines added (recombinant human interleukin-2 [rhIL-2] and rhIL-7). The amounts of antigen-presenting monocytes, followed by the concentration of exogenous rhIL-2, had the most pronounced and significant effects in enhancing sensitivity of the ELISPOT assay. Blood samples from six patients being monitored for abnormal Pap smear results and from 12 healthy volunteers were examined using the enhanced conditions.
Toxin Profiles and Resistances to Macrolides and Newer Fluoroquinolones as Epidemicity Determinants of Clinical Isolates of
Clostridium difficile
from Warsaw, Poland
Authors: Pituch Hanna , van Leeuwen Willem , Maquelin Kees , Wultańska Dorota , Obuch-Woszczatyński Piotr , Nurzyńska Grazyna , Kato Haru , Reijans Martin , Meisel-Mikołajczyk Felicja , Łuczak Mirosław , van Belkum Alex 
Published: February 2007

ABSTRACT

Amplified fragment length polymorphism genotypes, antibiotic resistance profiles, and toxin profiles of
Clostridium difficile
strains from Warsaw were determined. The isolates segregate in six major genotypes, coinciding with toxin profiles. Most of the toxin A-negative toxin B-positive toxin CDT-negative strains possess
ermB
, and several strains were resistant to fluoroquinolones. Resistograms and toxin types of
C. difficile
strains are epidemicity determinants.