bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging features of orbital and ocular adnexal lymphomas
Authors: RYSANEK B , MOURIAUX F
Published: September 2008

Purpose Lymphoma is the most frequent primary orbital tumour in adults. Imaging diagnosis is a useful tool but is not specific.

Methods A non comparative retrospective review of clinical and imaging characteristics between 1996 and 2006 was conducted in our department. Included patients consisted of orbital or lacrymal gland lymphoma with Magnetic Resonance Imaging (MRI) and/or Computed Tomography (CT) imaging.

Results Ten patients were assessed. CT‐scan and MRI‐scan showed a well‐circumscribed homogenous lesion moulding at adjacent tissues. Lack of calcifications and lack of bone destruction were observed in all cases. Most lesions were localized in the anterior extraconal orbit. Doppler showed an hypoechogenic hypervascularised lesion.

Conclusion Imaging of orbital lymphomas was not specific but some characteristics were highly evocative. Imaging cannot differentiate lymphoma from some metastasis or non specific inflammation. However, imaging can in most cases differentiate lymphoma from primary tumours.
Isolated optic nerve involvement in chronic lymphocytic leukaemia
Authors: BONSHEK RE , COOK A , IRION LD
Published: September 2008

Purpose We present a case of isolated optic nerve involvement by B‐cell small lymphocytic lymphoma/chronic lymphocytic lymphoma (SLL/CLL).

Methods A 57 year old woman with CLL stage 1 developed right‐sided visual loss progressing to blindness. There was optic disc swelling and secondary central retinal vein occlusion (CRVO). Imaging revealed a thickened right optic nerve. A clinical diagnosis of optic nerve sheath meningioma was made. Biopsies were taken from optic nerve sheath and abnormal‐looking optic nerve tissue.

Results Histopathology revealed infiltration of optic nerve by small B‐cell lymphoma, with CD5, CD20 and CD23 positive, cyclin D1 negative, neoplastic B‐cells, with kappa light chain restriction. Molecular genetic analysis with heavy chain primers confirmed a dominant band of PCR products, consistent with monoclonal B‐cell expansion. This lymphoma phenotype was consistent with that of the previously diagnosed stage 1 CLL. Optic nerve sheath dura was uninvolved, with reactive meningeal hyperplasia only.

Conclusion Although primary intraocular lymphoma and optic nerve lymphoma are present in up to 20% of cases of primary central nervous system lymphoma, isolated optic nerve lymphoma is rare. We believe this case is only the sixth reported where optic nerve biopsy was diagnostic. Other authors have noted the lack of dural involvement by lymphoma in this condition. We wish to add that in addition to potential diagnostic failure if optic nerve sheath alone is biopsied, the presence of reactive meningeal hyperplasia might lead to an erroneous diagnosis of optic nerve sheath meningioma on an inadequate biopsy specimen. Also, it is possible for accurate diagnosis to be achieved without sacrificing the optic nerve, although visual loss may not be avoided.
Spectrum of conjunctival tumors in an ocular oncology unit: review of 314 cases
Authors: PORTERO‐BENITO A , SANCHEZ‐MANNARELLI F , CARRENO‐SALAS E , MUNOZ MF , SAORNIL MA
Published: September 2008

Purpose To report the frequency and spectrum of conjuctival tumors in an Ocular Oncology Unit from 1992 to 2008.

Methods Retrospective noninterventional case series. Review of clinical charts of patients with the diagnosis of conjunctival tumor diagnosed at the Ocular Oncology Unit of the University Hospital of Valladolid from 1992 to june 2008. Demographic information and tumor features were introduced in Microsoft Access database. Results were analyzed with SPSS (version 15.0).

Results Among a total of 314 cases, the mean patient age at diagnosis was 49 years, 43.3% were females and 56.7% males. Regarding the diagnosis, 149 cases (47.6%) were melanocytic, 124 (39.6%) epithelial, 30 (9.6%) soft tissues and 10 cases (3.2%) lymphoid origin. The majority of tumors were benign (63.9%) followed by the precancerous lesions (28.1%). Most of melanocytic lesions were benign (87.9%) and most epithelial were precancerous (64.5%).

Conclusion Most frequent conjunctival tumors were melanocytic origin (the majority benign) and epithelial (the majority precancerous). Melanocytic, epithelial and lymphoyd tumors accounted for 90% of cases. These results are similar to others series previously published.
Iodine ‐125 episcleral brachytherapy for uveal melanoma : 133 cases
Authors: CEBALLOS GARCIA A , GARCIA ALVAREZ C , SAORNIL MA , LOPEZ‐LARA‐MARTIN F , MUNOZ MF , DE FRUTOS‐BARAJA JM , ALMARAZ A , GIRALDO‐ARGÜELLO A
Published: September 2008

Purpose To assess the results of I125 Episcleral Brachytherapy (EB) in uveal melanoma: tumor control, visual acuity, eye preservation and survival

Methods Prospective and consecutive study of patients with the diagnosis of uveal melanoma at the ocular oncology unit in the Valladolid University Hospital treated with EB between september 1997 and june 2008. Ocular examination, extraocular and systemic extension data have been registered in a database at the time of the diagnosis and during the follow up.

Results Among a total of 310 patients diagnosed between September 1997 and June 2008, 133 were treated with EB with a mean age of 58.6 years. Mean follow up was 45.4 months. The onset was symptomatic in 78.2% and 66.9% were nodular and 30.1% mushroom shape. Regarding the size 80.5% were medium, 7.5 % small and 12% large. The median tumor height were 5.7 mm and median basal diameter 12 mm. The median dose to tumor apex delivered 89.6 Gy. After 4.9 year of follow up tumor were controlled in 99% with a 57.9% reduction in the mean height; only two patients showed recurrence; 64.1.% maintain visual acuity > 0.1 and 33.3% > 0.5 with . Only 7 patients underwent enucleation due to complications and there are 1 death related to melanoma up to date.

Conclusion I125 Episcleral Brachytherapy is effective regarding tumour control, allowing preservation of the eye and useful visual function for the majority of patients with uveal melanoma.
Case of choroidal melanoma with massive extraocular extension through sclera
Authors: KIMURA M , OGATA N , TAKAHASHI K , SHIMA C , NISHIMURA T
Published: September 2008

Purpose To report a case of choroidal melanoma with massive extraocular extension through the sclera.

Methods A 64‐year‐old woman presented visual impairment in the right eye with a few months duration. On her first visit, her corrected visual acuity was 10/20 OD. Ocular examination revealed a raised choroidal mass behind the lens and serous retinal detachment in the lower retina. The choridal mass showed a mushroom shaped solid lesion on ultrasonography. The diagnosis of peripheral choroidal melanoma was confirmed by further examinations with the computed tomography, magnetic resonance imaging, and brain perfusion scintigraphy.

Results Because no systemic metastasis was found, we proposed her enucleation. However, she refused the enucleation and wished to be followed without any treatment. Seven months later, the tumor showed extraocular extension, and invasion of the subconjunctiva through the sclera. Finally, her right eyeball was enucleated. Histopathologically, the tumor was determined as mixed cell malignant melanoma of the choroid. The eyeball was congested with tumor cells and the tumor showed massive extraocular extension through the sclera to the orbit. The intraocular tumor presented marked necrotic lesions that indicate rapid growth of the tumor.

Conclusion Choroidal melanoma extends rapidly, and resulted in extraocular extension through the sclera.
Electronic vs paper based clinical pathway for episcleral brachytherapy. Preliminary results
Authors: DE FRUTOS‐BARAJA JM , DE LUIS‐PEREZ FJ , SAORNIL‐ALVAREZ MA , LOPEZ‐LARA‐MARTIN F , CEBALLOS‐GARCIA MA , GARCIA‐ALVAREZ C , ANDRES RODRIGUEZ C
Published: September 2008

Purpose To evaluate the clinical pathway for electronic episcleral brachytherapy and their comparison with the paper‐based format.

Methods Patients: Patients diagnosed with choroidal melanoma or angioma treated with epiescleral brachytherapy in our hospital since the entry into operation of the clinical pathway. The electronic clinical pathway was developed with an database Access. To quantify the following variances regarding the clinical pathway, in two formats are examined: The number of variances, number of patients with variances, variances related to patient‐related professionals, related to the hospital, not attributable to any of the above, correctable and not correctable. Data treatment: chi‐square test to determine the differences between the variations of the two formats clinical pathway is employed. The data were analyzed using a spreadsheet Excel and SPSS statistical application.

Results There were no significant differences between the completion of both formats clinical pathway.

Conclusion The computerisation benefit the continuity of the records of patients, allows easy access to information and provides a tool to monitor and evaluate the provision of care. It is described that help the decision‐making in the individualized treatment and allows the work in ways that are not possible in paper‐based environments. Acknowledgments: This work has been financed partly by a grant of the Junta de Castilla y León (Order SAN/1829/2007 of November 13, BOCYL of November 15, 2007)
Human papillomavirus DNA in pterygia
Authors: PIECYK‐SIDOR M , POLZ‐DACEWICZ M , ZAGORSKI Z , ZARNOWSKI T
Published: September 2008

Purpose To examine pterygium and normal conjunctiva tissue for the presence of human papillomavirus (HPV) and to determine the genotypes of HPV.

Methods METHODS: The study involved 89 patients undergoing surgical procedures at the I Department of Ophthalmology, Medical University of Lublin, Poland. Patients were divided into 2 groups: group I with pterygium (n = 58; 51 primary, 7 recurrences) and group II with with normal conjunctiva (n=31). The material was collected during elective surgical procedures. Specimens were tested for the presence of HPV genome using polymerase chain reaction (PCR). Once the presence of HPV DNA was confirmed, 28 HPV genotypes were determined using reverse hybridisation.

Results In group I, HPV DNA was identified in 16 patients (27.6%) whereas in group II ‐ in 3 cases (9.7%). Moreover, there was a statistically significant difference in the presence of HPV genome in pterygium patients compared to those with no clinical lesions of the conjunctiva (p=0.041). HPV type 16 was most frequently observed in 56% of HPV positive cases of pterygium. In 19% of cases, HPV 16 and HPV 6 co‐infections were found while in 13% ‐ HPV 18 and HPV 6 co‐infections were detected. Amongst 7 cases of recurrent pterygium, HPV 16 was detected in 2 cases. In group II, all 3 patients with HPV showed HPV 18.

Conclusion In Poland, no studies concerning the presence of HPV in ocular lesions have been carried out. The group examined in our study is one of the largest populations of patients with pterygium studied for the presence of the HPV genome worldwide. Our findings show that HPV is likely to play a synergistic role in the multi‐stage process of the development of pterygium, although it is not necessary to induce this condition.
Topical use of Nerve Growth Factor on ocular flora and cytology in dogs eye surface
Authors: DODI PL , ZANOTTI C , COSTA N , ALOE L
Published: September 2008

Purpose To investigate if topical Nerve Growth Factor (NGF) affects the ocular flora and to study corneal conjunctival cytology in dogs with different eye surface disease.

Methods The present study has been conducted on 9 dogs (18 eyes) affected by different ocular surface disease. The dogs were various ages (from 2 to 10 years old) and different sexes (5 males ‐ 4 females). 6 dogs were affected by dry eye, 1 had a superficial keratitis and 2 dogs had a cornea ulcer. All dogs underwent the following examinations: cornea evaluation by slit lamp, fluorescent staining, Schirmer tear test I (STT I), corneal and conjunctival cytology. All samples made with ocular swabs were placed in a sterile blood agar. 6 dogs showed no bacteria, 3 dogs displayed Staphylococcus spp. Cytology pointed out many inflammatory cells. The dogs were topically treated with purified murine NGF diluted in paraffin oil (200 microg/ml) for 4 weeks (50 microg every 12 h).

Results The result revealed that all swabs were sterile, while the cytology analysis showed a significant reduction in the number of corneal inflammatory cells. This latter observation is related to a decrease of the corneal inflammatory reduction.

Conclusion This report demonstrated that NGF exerts an antibacterial and anti inflammatory activity that confirmed and extended previous evidences on NGF research. Moreover, our results suggest a potential therapeutic use of NGF in dogs with different ocular inflammatory surface. However, further clinical studies need to be done to assess the consistency of this clinic approach.
One year analysis of the cost of uveitis treatment in France: a retrospective chart review
Authors: BODAGHI B , KOBELT G , RICHARD B , PLESNILLA C , BUCHHOLZ P , BREZIN A , HERON E , LABETOULLE M , SAHEL JA
Published: September 2008

Purpose To determine current treatment strategies and evaluate one year consumption of health care resources for patients with uveitis in France.

Methods Review of consecutive patients (N = 100) from 4 French referral centers with 12 months follow‐up after the first visit. Data abstracted from the patient charts included basic demographic data, characterizing clinical parameters, and all disease‐ or treatment‐related resource consumption. Direct health care costs were estimated using publicly available standard unit costs. Indirect costs were based on standard sick leave for each type of inpatient admission or outpatient intervention and a gender‐specific cost of employment.

Results 82% of patients were below age 60 (retirement age). Diseases were: posterior uveitis (36%), panuveitis (33%), chronic anterior (24%) and intermediate (7%). Patients received drug treatments (91%), triamcinolone or dexamethasone injections (8%), and laser treatment (2%). Mean direct costs per patient were €3403. Inpatient stays accounted for the largest proportion, with a mean cost of €2889 per year. For patients below 60 years with an admission or intervention, the estimated average productivity loss was €1750, leading to a mean indirect cost of €830 per patient. The estimated total minimum annual costs per patient were €4230.

Conclusion Annual treatment costs in this sample were driven by frequent, extended inpatient stays. This may be due to the more severely diseased patients treated by these specialized centers. In the current sample, most patients were of working age, suggesting a substantial amount of indirect costs arising from sick leave.

Commercial interest
Genetic analysis of pseudomonas aeruginosa isolates from patients with post‐operative endophthalmitis
Authors: PINNA A , USAI D , SECHI LA , ZANETTI S , KALIAMURTHY J
Published: September 2008

Purpose To establish clonal relationship between strains of Pseudomonas aeruginosa isolated from 24 patients with postoperative endophthalmitis following cataract surgery

Methods All the patients with postoperative endophthalmitis were operated at the same operation theatre in the same hospital in Tiruchirapalli, Tamil Nadu, India. All the cases occurred within a time period of one month. Polymerase chain reaction (PCR) with enterobacterial repetitive intergenic consensus (ERIC) primers (ERIC‐PCR) was used to establish clonal relationship between the different isolates.

Results ERIC‐PCR disclosed 4 different patterns. Seventeen isolates showed an identical pattern, whereas 2 other strains were closely correlated with the former 17. Two other isolates, with identical ERIC‐PCR pattern, were genetically similar, but to a lesser extent, to the first group. The remaining 3 isolates showed identical ERIC‐PCR pattern, but they were less correlated with the other strains.

Conclusion The results of this study indicate that the outbreak of postoperative P. aeruginosa endophthalmitis presented here was caused predominantly by isolates with identical or very similar genetic patterns, thus suggesting a common source of infection in most cases. ERIC‐PCR appears to be an inexpensive, fast, reproducible, and discriminatory DNA typing tool for effective epidemiological surveillance of outbreaks of P. aeruginosa eye infections.
The corneal endothelium in an endotoxin‐induced uveitis model: Correlation between in vivo confocal microscopy and immunohistochemistry
Authors: TRINH L , BRIGNOLE‐BAUDOUIN F , LABBE A , RAPHAEL M , BOURGES JL , BAUDOUIN C
Published: September 2008

Purpose To analyze the involvement of the corneal endothelium in uveitis in order to better understand the formation mechanisms and the keratic precipitate composition. In vivo confocal microscopy images were correlated with ex vivo immunostaining of corneal endothelium from rat eyes with endotoxin‐induced uveitis (EIU).

Methods EIU was induced in Lewis rats by lipopolysaccharide (LPS) injection. Slit‐lamp examination and in vivo confocal microscopy were performed 6, 24, 48, 72 and 96 h after the LPS injection. Immunohistochemistry on corneal endothelium, using antibodies to ICAM‐1, phalloidin, CD68 (anti‐macrophage), MA967 (anti‐granulocyte), alpha beta‐TCR (anti‐lymphocyte) was performed on flat‐mount corneas and was analyzed using a 3D laser confocal microscope.

Results In vivo confocal microscopy showed numerous hyper‐reflective round dots on the corneal endothelium, in the anterior chamber and in the anterior stroma corresponding to inflammatory cells until 96 h, peaking at 24 h. On immunostaining, corneal endothelial cells in rats with EIU overexpressed ICAM‐1. Compared to controls, CD68, MA 967 and alpha beta‐TCR expression was observed in corneas in rats with EIU.

Conclusion The correlation between in vivo confocal microscopy and ex vivo immunostaining helped to better understand in vivo confocal microscopy images. The two new techniques applied here were very effective and complementary in evaluating the corneal endothelium involvement in EIU. Based on these findings, in vivo confocal microscopy in clinical practice could be very helpful to better analyze keratic precipitates and corneal modifications in patients with uveitis.
Performance evaluation of an improved optical computed tomography polymer gel dosimeter system for 3D dose verification of static and dynamic phantom deliveries
Authors: Lopatiuk‐Tirpak O. , Langen K. M. , Meeks S. L. , Kupelian P. A. , Zeidan O. A. , Maryanski M. J.
Published: September 2008

The performance of a next‐generation optical computed tomography scanner (OCTOPUS™‐5X) is characterized in the context of three‐dimensional gel dosimetry. Large‐volume , muscle‐equivalent, radiation‐sensitive polymer gel dosimeters (BANG®‐3) were used. Improvements in scanner design leading to shorter acquisition times are discussed. The spatial resolution, detectable absorbance range, and reproducibility are assessed. An efficient method for calibrating gel dosimeters using the depth‐dose relationship is applied, with photon‐ and electron‐based deliveries yielding equivalent results. A procedure involving a preirradiation scan was used to reduce the edge artifacts in reconstructed images, thereby increasing the useful cross‐sectional area of the dosimeter by nearly a factor of 2. Dose distributions derived from optical density measurements using the calibration coefficient show good agreement with the treatment planning system simulations and radiographic film measurements. The feasibility of use for motion (four‐dimensional) dosimetry is demonstrated on an example comparing dose distributions from static and dynamic delivery of a single‐field photon plan. The capability to visualize three‐dimensional dose distributions is also illustrated.
Use of a two‐dimensional ionization chamber array for proton therapy beam quality assurance
Authors: Arjomandy Bijan , Sahoo Narayan , Ding Xiaoning , Gillin Michael
Published: September 2008

Two‐dimensional ion chamber arrays are primarily used for conventional and intensity modulated radiotherapy quality assurance. There is no commercial device of such type available on the market that is offered for proton therapy quality assurance. We have investigated suitability of the MatriXX, a commercial two‐dimensional ion chamber array detector for proton therapy QA. This device is designed to be used for photon and electron therapy QA. The device is equipped with parallel plate ion chambers, each with diam and center‐to‐center separation. A proton beam was used to calibrate the dose measured by this device. The water equivalent thickness of the buildup material was determined to be using a proton beam. Proton beams of different energies were used to measure the reproducibility of dose output and to evaluate the consistency in the beam flatness and symmetry measured by MatriXX. The output measurement results were compared with the clinical commissioning beam data that were obtained using a 0.6 cc Farmer chamber. The agreement was consistently found to be within 1%. The profiles were compared with film dosimetry and also with ion chamber data in water with an excellent agreement. The device is found to be well suited for quality assurance of proton therapy beams. It provides fast two‐dimensional dose distribution information in real time with the accuracy comparable to that of ion chamber measurements and film dosimetry.
Tumor tracking and motion compensation with an adaptive tumor tracking system (ATTS): System description and prototype testing
Authors: Wilbert Jürgen , Meyer Jürgen , Baier Kurt , Guckenberger Matthias , Herrmann Christian , Heß Robin , Janka Christian , Ma Lei , Mersebach Torben , Richter Anne , Roth Michael , Schilling Klaus , Flentje Michael
Published: September 2008

A novel system for real‐time tumor tracking and motion compensation with a robotic HexaPOD treatment couch is described. The approach is based on continuous tracking of the tumor motion in portal images without implanted fiducial markers, using the therapeutic megavoltage beam, and tracking of abdominal breathing motion with optical markers. Based on the two independently acquired data sets the table movements for motion compensation are calculated. The principle of operation of the entire prototype system is detailed first. In the second part the performance of the HexaPOD couch was investigated with a robotic four‐dimensional‐phantom capable of simulating real patient tumor trajectories in three‐dimensional space. The performance and limitations of the HexaPOD table and the control system were characterized in terms of its dynamic behavior. The maximum speed and acceleration of the HexaPOD were and in the lateral direction, and and in longitudinal and anterior‐posterior direction, respectively. Base line drifts of the mean tumor position of realistic lung tumor trajectories could be fully compensated. For continuous tumor tracking and motion compensation a reduction of tumor motion up to 68% of the original amplitude was achieved. In conclusion, this study demonstrated that it is technically feasible to compensate breathing induced tumor motion in the lung with the adaptive tumor tracking system.
An easy‐to‐use phantom and protocol for weekly PET quality assessment: A multicenter study
Authors: Vermandel M. , Fin L. , Hapdey S. , Bol A. , Betrouni N. , Daouk J. , Gardin I. , Lee J. , Jounwaz R. , Rousseau J. , Huglo D.
Published: September 2008

The authors have developed a simple phantom and dedicated software for the quality assessment of positron emission tomography (PET) scanners. The phantom is a parallelepiped box filled with a relatively low activitysolution and in which simple test objects are placed. Various image quality parameters are checked, including signal‐to‐noise ratio, image uniformity, slice thickness, slice sensitivity profile, spatial resolution, and dose calibration accuracy. Automatic image analysis consists in detecting surfaces and objects, defining regions of interest, acquiring reference point coordinates, and establishing gray‐scale profiles. The total time needed for quality assessment (preparation and image acquisition) is less thanwith. The system's ease of use encourages frequent image quality assessment—for example, the comparison of PET scanners in interdepartment studies and the monitoring and evaluation of possible drifts over time. By way of an example, the authors present weekly quality assessment results obtained over up to 7 months at four PET facilities.
Combining segment generation with direct step‐and‐shoot optimization in intensity‐modulated radiation therapy
Authors: Carlsson Fredrik
Published: September 2008

A method for generating a sequence of intensity‐modulated radiation therapy step‐and‐shoot plans with increasing number of segments is presented. The objectives are to generate high‐quality plans with few, large and regular segments, and to make the planning process more intuitive. The proposed method combines segment generation with direct step‐and‐shoot optimization, where leaf positions and segment weights are optimized simultaneously. The segment generation is based on a column generation approach. The method is evaluated on a test suite consisting of five head‐and‐neck cases and five prostate cases, planned for delivery with an Elekta SLi accelerator. The adjustment of segment shapes by direct step‐and‐shoot optimization improves the plan quality compared to using fixed segment shapes. The improvement in plan quality when adding segments is larger for plans with few segments. Eventually, adding more segments contributes very little to the plan quality, but increases the plan complexity. Thus, the method provides a tool for controlling the number of segments and, indirectly, the delivery time. This can support the planner in finding a sound trade‐off between plan quality and treatment complexity.
Dosimetric evaluation of a dedicated stereotactic linear accelerator using measurement and Monte Carlo simulation
Authors: Heydarian M. , Asnaashari K. , Allahverdi M. , Jaffray D. A.
Published: September 2008

Dosimetric parameters of a dedicated stereotactic linear accelerator have been investigated using measurements and Monte Carlo simulations. This linac has a unique built in multileaf collimation (MLC) system with the maximum opening of and leaf width at the isocenter and has successfully been modeled for the first time using the Monte Carlo simulation. The high resolution MLC, combined with its relatively large maximum field size, opens up a new opportunity for expanding stereotactic radiation treatment techniques from traditionally treating smaller targets to larger ones for both cranial and extracranial lesions. Dosimetric parameters of this linac such as accuracy of leaf positioning and field shaping, leakage and transmission, percentage depth doses, off‐axes dose profiles, and dose penumbras were measured and calculated for different field sizes, depths, and source to surface distances. In addition, the ability of the linac in accurate dose delivery of several treatment plans, including intensity modulated radiation therapy (IMRT), performed on phantom and patients was determined. Ionization chamber, photon diode detector, films, several solid water phantoms, and a water tank were used for the measurements. The MLC leaf positioning to any particular point in the maximum aperture was accurate with a standard deviation of . Maximum and average leakages were 1.7% and 1.1% for the reference field of . Measured penumbra widths (80%–20%) for this field at source axis distance (SAD) of at a depth of were 3.2 and for the leaf‐sides and leaf‐ends, respectively. The corresponding results at depth and were 5.4 and . Monte Carlo results generally agreed with the measurements to within 1% and or , with respective uncertainties of 0.5% and . The linac accuracy in delivering non‐IMRT treatment plans was better than 1%. Ionization chamber dosimetry results for a phantom IMRT plan in the high dose and low dose regions were and , respectively. Dosimetry results at isocenter for three patients’ IMRT plans were measured to be within 3% of their corresponding treatment plans. Film dosimetry was also used to compare dose distributions of IMRT treatment plans and delivered cumulative doses at different cross sectional planes.
An enhanced HOWFARLESS option for DOSXYZnrc simulations of slab geometries
Authors: Babcock Kerry , Cranmer‐Sargison Gavin , Sidhu Narinder
Published: September 2008

The Monte Carlo code DOSXYZnrc is a valuable instrument for calculating absorbed dose within a three‐dimensional Cartesian geometry. DOSXYZnrc includes several variance reduction techniques used to increase the efficiency of the Monte Carlo calculation. One such technique is HOWFARLESS which is used to increase the efficiency of beam commissioning calculations in homogeneous phantoms. The authors present an enhanced version of HOWFARLESS which extends the application to include phantoms inhomogeneous in one dimension. When the enhanced HOWFARLESS was used, efficiency increases as high as 14 times were observed without any loss in dose accuracy. The efficiency gains of an enhanced HOWFARLESS simulation was found to be dependent on both slab geometry and slab density. As the number of two‐dimensional voxel layers per slab increases, so does the efficiency gain. Also, as the mass density of a slab is decreased, the efficiency gains increase.
Geometrical differences in target volumes between slow CT and 4D CT imaging in stereotactic body radiotherapy for lung tumors in the upper and middle lobe
Authors: Nakamura Mitsuhiro , Narita Yuichiro , Matsuo Yukinori , Narabayashi Masaru , Nakata Manabu , Yano Shinsuke , Miyabe Yuki , Matsugi Kiyotomo , Sawada Akira , Norihisa Yoshiki , Mizowaki Takashi , Nagata Yasushi , Hiraoka Masahiro
Published: September 2008

Since stereotactic body radiotherapy (SBRT) was started for patients with lung tumor in 1998 in our institution, x‐ray fluoroscopic examination and slow computed tomography (CT) scan with a rotation time of have been routinely applied to determine target volumes. When lung tumor motion observed with x‐ray fluoroscopy is larger than , diaphragm control (DC) is used to reduce tumor motion during respiration. After the installation of a four‐dimensional (4D) CT scanner in 2006, 4D CT images have been supplementarily acquired to determine target volumes. It was found that target volumes based on slow CT images were substantially different from those on 4D CT images, even for patients with lung tumor motion no larger than . Although slow CT scan might be expected to fare well for lung tumors with motion range of or less, the potential limitations of slow CT scan are unknown. The purpose of this study was to evaluate the geometrical differences in target volumes between slow CT and 4D CT imaging for lung tumors with motion range no larger than in the upper and middle lobe. Of the patients who underwent SBRT between October 2006 and April 2008, 32 patients who had lung tumor with motion range no larger than and did not need to use DC were enrolled in this study. Slow CT and 4D CT images were acquired under free breathing for each patient. Target volumes were manually delineated on slow CT images . Gross tumor volumes were also delineated on each of the 4D CT volumes and their union was constructed. Volumetric and statistical analyses were performed for each patient. The deviation (S.D.) of was (range, 0.38–1.10). The difference between sizes of and was not statistically significant . A mean of 8% volume of was not encompassed in . The patients were separated into two groups to test whether the quality of target delineation on slow CT scans depends on respiratory periods below or above the CT rotation time of . No significant difference was observed between these groups . Even lung tumors with motion range no larger than might not be accurately depicted on slow CT images. When only a single slow CT scan was used for lung tumors with motion range of or less, 95% confidence values for additional margins for to encompass were 4.0, 5.4, 4.9, 5.1, 1.8, and for lateral, medial, ventral, dorsal, cranial, and caudal directions, respectively.
Thermoluminescence dosimetry measurements of brachytherapy sources in liquid water
Authors: Tailor Ramesh , Tolani Naresh , Ibbott Geoffrey S.
Published: September 2008

Radiation therapy dose measurements are customarily performed in liquid water. The characterization of brachytherapy sources is, however, generally based on measurements made with thermoluminescence dosimeters (TLDs), for which contact with water may lead to erroneous readings. Consequently, most dosimetry parameters reported in the literature have been based on measurements in water‐equivalent plastics, such as Solid Water™. These previous reports employed a correction factor to transfer the dose measurements from a plastic phantom to liquid water. The correction factor most often was based on Monte Carlo calculations. The process of measuring in a water‐equivalent plastic phantom whose exact composition may be different from published specifications, then correcting the results to a water medium leads to increased uncertainty in the results. A system has been designed to enable measurements with TLDs in liquid water. This system, which includes jigs to support water‐tight capsules of lithium fluoride in configurations suitable for measuring several dosimetric parameters, was used to determine the correction factor from water‐equivalent plastic to water. Measurements of several and prostate brachytherapy sources in liquid water and in a Solid Water™ phantom demonstrated a correction factor of at distance. These measurements are in good agreement with a published value of this correction factor for an source.
Monte Carlo calculations of correction factors for plane‐parallel ionization chambers in clinical electron dosimetry
Authors: Araki Fujio
Published: September 2008

Recent standard dosimetry protocols recommend that plane‐parallel ionization chambers be used in the measurements of depth‐dose distributions or the calibration of low‐energy electron beams with beam quality . In electron dosimetry protocols with the plane‐parallel chambers, the wall correction factor, , in water is assumed to be unity and the replacement correction factor, , is taken to be unity for well‐guarded plane‐parallel chambers, at all measurement depths. This study calculated and for NACP‐02, Markus, and Roos plane‐parallel chambers in clinical electron dosimetry using the EGSnrc Monte Carlo code system. The values for the plane‐parallel chambers increased rapidly as a function of depth in water, especially at lower energy. The value around for NACP‐02 was about 10% greater than unity at . The effect was smaller for higher electron energies. Similarly, values with depth increased drastically at the region with the steep dose gradient for lower energy. For Markus departed more than 10% from unity close to due to the narrow guard ring width. for NACP‐02 and Roos was close to unity in the plateau region of depth‐dose curves that includes a reference depth, . It was also found that the ratio of the dose to water and the dose to the sensitive volume in the air cavity for the plane‐parallel chambers, , at differs significantly from that assumed by electron dosimetry protocols.
An energy transfer method for 4D Monte Carlo dose calculation
Authors: Siebers Jeffrey V. , Zhong Hualiang
Published: September 2008

This article presents a new method for four‐dimensional Monte Carlo dose calculations which properly addresses dose mapping for deforming anatomy. The method, called the energy transfer method (ETM), separates the particle transport and particle scoring geometries: Particle transport takes place in the typical rectilinear coordinate system of the source image, while energy deposition scoring takes place in a desired reference image via use of deformable image registration. Dose is the energy deposited per unit mass in the reference image. ETM has been implemented into DOSXYZnrc and compared with a conventional dose interpolation method (DIM) on deformable phantoms. For voxels whose contents merge in the deforming phantom, the doses calculated by ETM are exactly the same as an analytical solution, contrasting to the DIM which has an average 1.1% dose discrepancy in the beam direction with a maximum error of 24.9% found in the penumbra of a beam. The DIM error observed persists even if voxel subdivision is used. The ETM is computationally efficient and will be useful for 4D dose addition and benchmarking alternative 4D dose addition algorithms.
An improved method for simulating microcalcifications in digital mammograms
Authors: Zanca Federica , Chakraborty Dev Prasad , Van Ongeval Chantal , Jacobs Jurgen , Claus Filip , Marchal Guy , Bosmans Hilde
Published: September 2008

The assessment of the performance of a digital mammography system requires an observer study with a relatively large number of cases with known truth which is often difficult to assemble. Several investigators have developed methods for generating hybrid abnormal images containing simulated microcalcifications. This article addresses some of the limitations of earlier methods. The new method is based on digital images of needle biopsy specimens. Since the specimens are imaged separately from the breast, the microcalcification attenuation profile scan is deduced without the effects of over and underlying tissues. The resulting templates are normalized for image acquisition specific parameters and reprocessed to simulate microcalcifications appropriate to other imaging systems, with different x‐ray, detector and image processing parameters than the original acquisition system. This capability is not shared by previous simulation methods that have relied on extracting microcalcifications from breast images. The method was validated by five experienced mammographers who compared 59 pairs of simulated and real microcalcifications in a two‐alternative forced choice task designed to test if they could distinguish the real from the simulated lesions. They also classified the shapes of the microcalcifications according to a standardized clinical lexicon. The observed probability of correct choice was 0.415, 95% confidence interval (0.284, 0.546), showing that the radiologists were unable to distinguish the lesions. The shape classification revealed substantial agreement with the truth (mean ), showing that we were able to accurately simulate the lesion morphology. While currently limited to single microcalcifications, the method is extensible to more complex clusters of microcalcifications and to three‐dimensional images. It can be used to objectively assess an imaging technology, especially with respect to its ability to adequately visualize the morphology of the lesions, which is a critical factor in the benign versus malignant classification of a lesion detected in screening mammography.
Closed bore XMR (CBXMR) systems for aortic valve replacement: Investigation of rotating‐anode x‐ray tube heat loadability
Authors: Bracken John A. , Lillaney Prasheel V. , Fahrig Rebecca , Rowlands J. A.
Published: September 2008

In order to improve the safety and efficacy of percutaneous aortic valve replacement procedures, a closed bore hybrid x‐ray/MRI (CBXMR) system is proposed in which an x‐ray C‐arm will be positioned with its isocenter from the entrance of a clinical MRI scanner. This system will harness the complementary strengths of both modalities to improve clinical outcome. A key component of the CBXMR system will be a rotating anode x‐ray tube to produce high‐quality x‐ray images. There are challenges in positioning an x‐ray tube in the magnetic fringe field of the MRI magnet. Here, the effects of an external magnetic field on x‐ray tube induction motors of radiography x‐ray tubes and the corresponding reduction of x‐ray tube heat loadability are investigated. Anode rotation frequency was unaffected when the external magnetic field was parallel to the axis of rotation of the anode but decreased when was perpendicular to the axis of rotation. The experimental values agreed with predicted values to within over a range of . The MRI fringe field at the proposed location of the x‐ray tube mounted on the C‐arm reduced by only 1%, so x‐ray tube heat loadability will not be compromised when using CBXMR systems for percutaneous aortic valve replacement procedures. Eddy current heating power in the rotor due to an MRI fringe field was found to be two orders of magnitude weaker than the heating power produced on the anode due to a fluoroscopic exposure, so eddy current heating had no effect on x‐ray tube heat loadability.
Live level set: A hybrid method of livewire and level set for medical image segmentation
Authors: Yao Jianhua , Chen David
Published: September 2008

Livewire and level set are popular methods for medical image segmentation. In this article, the authors propose a hybrid method of livewire and level set, termed the live level set (LLS). The LLS replaces the one graph update iteration in the classic livewire with two iterations of graph updates. The first iteration generates an initial contour for a level set computation. The level set distance is then factored back into the cost function in the second iteration of graph update. The authors validated LLS using synthetic images. The results show that the performance of the LLS is superior to both the classic live wire and traditional level set methods in terms of accuracy, reproducibility, smoothness and running time. They also qualitatively evaluated the LLS using real clinical data.
Real‐time sonoelastography of hepatic thermal lesions in a swine model
Authors: Zhang Man , Castaneda Benjamin , Christensen Jared , Saad Wael , Bylund Kevin , Hoyt Kenneth , Strang John G. , Rubens Deborah J. , Parker Kevin J.
Published: September 2008

Sonoelastography has been developed as an ultrasound‐based elasticity imaging technique. In this technique, external vibration is induced into the target tissue. In general, tissue stiffness is inversely proportional to the amplitude of tissue vibration. Imaging tissue vibration will provide the elasticity distribution in the target region. This study investigated the feasibility of using real‐time sonoelastography to detect and estimate the volume of thermal lesions in porcine livers in vivo. A total of 32 thermal lesions with volumes ranging from were created using radiofrequency ablation (RFA) or high‐intensity focused ultrasound (HIFU) technique. Lesions were imaged using sonoelastography and coregistered B‐mode ultrasound. Volumes were reconstructed from a sequence of two‐dimensional scans. The comparison of sonoelastographic measurements and pathology findings showed good correlation with respect to the area of the lesions ( for RFA lesions, for HIFU lesions). In addition, good correspondence was found between three‐dimensional sonoelastography and gross pathology (3.6% underestimate), demonstrating the feasibility of sonoelastography for volume estimation of thermal lesions. These results support that sonoelastography outperforms conventional B‐mode ultrasound and could potentially be used for assessment of thermal therapies.
Some implications of linear‐quadratic‐linear radiation dose‐response with regard to hypofractionation
Authors: Astrahan Melvin
Published: September 2008

Recent technological advances enable radiation therapy to be delivered in a highly conformal manner to targets located almost anywhere in the body. This capability has renewed the clinical interest in hypofractionation wherein the tumor is delivered a few fractions of very large dose per fraction. Extrapolating clinical experience from conventional regimens to fractions of high dose is important to designing hypofractionated treatments. The concept of biologically effective dose (BED) based on the linear‐quadratic (LQ) formulation is a useful tool for intercomparing conventional fractionations but may be hampered if the value of is dose range dependent and/or when extrapolating to fractions of high dose because the LQ curve bends continuously on the log‐linear plot. This does not coincide with what is observed experimentally in many clonogenic cell survival studies at high dose wherein radiation dose‐response relationships more closely approximate a straight line. Intercomparison of conventional fractionations with hypofractionated regimens may benefit from BED calculations which instead use a dose range independent linear‐quadratic‐linear (LQ‐L) formulation which better fits the experimental data across a wider range of dose. The dosimetric implications of LQ‐L are explored using a simple model which requires only the specification of a dose at which the LQ curve transitions to final linearity and the cell kill per Gy in the final linear portion of the survival curve at high dose. It is shown that the line tangent to the LQ curve at transition dose can often be used to approximate the final slope of the dose response curve. When Gy, the line tangent to the LQ curve at intersects the and curves at dose Gy and also closely fits the linear response in the high dose region of some classic in vitro cell survival curves for which the value of is low. It is hypothesized that will increase as the magnitude of increases. Examples are presented illustrating how to recognize LQ‐L behavior in multifraction isoeffect studies of late responses such as spinal cord and lung. When planning hypofractionated regimens involving reactions with low , recognizing LQ‐L behavior could be important because the dose‐response is likely to transition to final linearity within the contemplated range of hypofractional doses.
Handbook of Radiotherapy Physics: Theory and Practice
Authors: Papanikolaou Niko
Published: September 2008

Handbook of Radiotherapy Physics: Theory and Practice Mayles P. Nahum A. Rosenwald J. C. Taylor & Francis Group, CRC Press, Boca Raton, FL, 2007. Hardcover 1470 pp. Price: $269.95. ISBN: 9780750308601.
Experience in nonlinear wave testing of constructions inside the earthquake area
Authors: Robsman Vadim A. , Stepanyan V. E.
Published: September 2008

In large-scale experiments on damaged engineering constructions disposed inside an earthquake area, the new nonlinear acoustic phenomena were observed which offer the possibility to evaluate the degree of dam- age and the strength of constructions. Specifically, the different parts of buildings (ground works, walls, etc.) were tested, as well as bridges damaged by catastrophic earthquake in Speatak, Armenia (1988). Such nonlinear technology was verified in the laboratory using a test seismic installation. Nonlinear testing was used later at the deep tunnel construction in rocks to predict the possible injury. Nonlinear effects were recorded in both transient internal radiation and in signals (regular and noise waves) generated by an external source. The direct relation was discovered between the rate of development of nonlinear distortion of spectra and the degree of damage of constructions subjected to earthquake shock.