Epiphysiolysis Type Salter I of the Medial Clavicle with Posterior Displacement: A Case Series and Review of the Literature.

Physeal fractures of the medial clavicle with posterior displacement of the metaphysis are very rare injuries, but additional injuries can be life-threatening. Due to the specific clavicular ossification process, skeletally immature patients present usually not true sternoclavicular joint (SCJ) dislocations accordingly to adults but rather displaced physeal fractures. There is no consensus in the current literature on the best treatment of this lesion. Conservative treatment is not resulting in good outcome; closed reduction is often not successful, and open reduction with internal fixation is finally required. Several methods are described for stabilizing these physeal fractures. We treated three osseous immature patients with this lesion. Due to the small dimension of the medial clavicular epiphysis, we performed in one case a transosseous figure-of-eight suture of the clavicular metaphysis towards the sternum, and in the two other cases, a transosseous suture from the clavicular metaphysis on the anterior clavicular periosteum. The latter technique avoids harm to the small epiphysis or the SCJ and minimizes the risk of retrosternal complications.

Comparison of multi-institutional pre-treatment verification for VMAT of nasopharynx with delivery errors.

PURPOSE: Measurement-based pre-treatment verification with phantoms frequently uses gamma analysis to assess acceptable delivery accuracy. This study evaluates the sensitivity of a commercial system to simulated machine errors for three different institutions' Volumetric Modulated Arc Therapy (VMAT) planning approaches. METHODS: VMAT plans were generated for ten patients at three institutions using each institution's own protocol (manually-planned at institution 1; auto-planned at institutions 2 and 3). Errors in Multi-Leaf Collimator (MLC) field size (FS), MLC shift (S), and collimator angle (C) of -5, -2, -1, 1, 2 and 5 mm or degrees were introduced. Dose metric constraints discriminated which error magnitudes were considered unacceptable. The smallest magnitude error treatment plans deemed clinically unacceptable (typically for a 5% dose change) were delivered to the ArcCHECK for all institutions, and with a high-dose point ion chamber measurement in 2 institutions. Error detection for different gamma analysis criteria was compared. RESULTS: Not all deliberately introduced VMAT plan errors were detected using a typical 3D 3%/3 mm global gamma pass rate of 95%. Considering all institutions, gamma analysis was least sensitive to negative FS errors. The most sensitive was a 2%/2 mm global analysis for institution 1, whilst for institution 2 it was 3%/3 mm global analysis. The majority of errors (58/59 for institution 1, 54/60 for institution 3) were detected using ArcCHECK and ion chamber measurements combined. CONCLUSIONS: Not all clinically unacceptable errors are detected. Combining ion chamber measurements with gamma analysis improved sensitivity and is recommended. Optimum gamma settings varied across institutions.

A simple model for transit dosimetry based on a water equivalent EPID.

PURPOSE: The aim of this study was to demonstrate a new model for implementing a transit dosimetry system as a means of in vivo dose verification with a water equivalent electronic portal imaging device (WE-EPID) and a conventional treatment planning system (TPS). METHOD AND MATERIALS: A standard amorphous silicon (a-Si) EPID was modified to a WE-EPID configuration by replacing the metal-plate/phosphor screen situated above the photodiode detector with a 3 cm thick water equivalent plastic x ray converter material. A clinical TPS was used to calculate dose to the WE-EPID in its conventional EPID position behind the phantom/patient. The "extended phantom" concept was used to facilitate dose calculation at the EPID position, which is outside the CT field of view (FOV). The CT images were manipulated from 512 × 512 into 1024 × 1024 and padded pixels were assigned the density of air before importing to the TPS. The virtual WE-EPID was added as an RT structure of water density at the EPID plane. The accuracy of TPS dose calculations at the EPID plane in transit geometry was first evaluated for different field sizes and thickness of object in the beam by comparison with the dose measured using a 2D ion chamber array (ICA) and the WE-EPID. Following basic dose response tests, clinical fields including direct single fields (open and wedged) and modulated fields (integrated or control point by control point doses for VMAT) were measured for 6 MV photons with varying of solid water thickness or an anthropomorphic phantom present in beam. The EPID images were corrected for dark signal and pixel sensitivity and converted to dose using a single dose calibration factor. The 2D dose evaluation was conducted using 3%/3 and 2%/2 mm gamma-index criteria. RESULTS: The measured dose-response with the ICA and WE-EPID for all basic dose-response tests agreed with TPS dose calculations to within 1.5%. The maximum difference in dose profiles for the largest measured field size of 25 × 25 cm2 was 2.5%. Gamma evaluation showed at least 94% (3%/3 mm criteria) and 90% (2%/2 mm) agreement in both integrated and control-point doses for all clinical fields acquired by the WE-EPID and ICA when compared with TPS-calculated portal dose images. CONCLUSION: A new approach to transit dose verification has been demonstrated utilizing a water equivalent EPID and a commercial TPS. The accuracy of dose calculations at the EPID plane using a commercial TPS beam model was experimentally confirmed. The model proposed in this study provides an accurate method to directly verify doses delivered during treatment without the additional uncertainties inherent in modelling the complex dose-response of standard EPIDs.

Technical Note: Experimental results from a prototype high-field inline MRI-linac.

PURPOSE: The pursuit of real-time image guided radiotherapy using optimal tissue contrast has seen the development of several hybrid magnetic resonance imaging (MRI)-treatment systems, high field and low field, and inline and perpendicular configurations. As part of a new MRI-linac program, an MRI scanner was integrated with a linear accelerator to enable investigations of a coupled inline MRI-linac system. This work describes results from a prototype experimental system to demonstrate the feasibility of a high field inline MR-linac. METHODS: The magnet is a 1.5 T MRI system (Sonata, Siemens Healthcare) was located in a purpose built radiofrequency (RF) cage enabling shielding from and close proximity to a linear accelerator with inline (and future perpendicular) orientation. A portable linear accelerator (Linatron, Varian) was installed together with a multileaf collimator (Millennium, Varian) to provide dynamic field collimation and the whole assembly built onto a stainless-steel rail system. A series of MRI-linac experiments was performed to investigate (1) image quality with beam on measured using a macropodine (kangaroo) ex vivo phantom; (2) the noise as a function of beam state measured using a 6-channel surface coil array; and (3) electron contamination effects measured using Gafchromic film and an electronic portal imaging device (EPID). RESULTS: (1) Image quality was unaffected by the radiation beam with the macropodine phantom image with the beam on being almost identical to the image with the beam off. (2) Noise measured with a surface RF coil produced a 25% elevation of background intensity when the radiation beam was on. (3) Film and EPID measurements demonstrated electron focusing occurring along the centerline of the magnet axis. CONCLUSIONS: A proof-of-concept high-field MRI-linac has been built and experimentally characterized. This system has allowed us to establish the efficacy of a high field inline MRI-linac and study a number of the technical challenges and solutions.

Caso clínico: hemangioma esclerosante (neumocitoma) pulmonar / Clinical case: lung sclerosing hemangioma (pneumo cytoma)

El objetivo de este artículo es presentar un caso de raro de tumor pulmonar benigno, hemangioma esclerosante (neumocitoma), en una mujer de 24 años, asintomática, con hallazgo radiológico incidental. Se describen las características clínicas, imagenológicos y anátomo-patológicos de la entidad, con una breve revisión bibliográfica.

We present a rare case of benign lung neoplasia, sclerosing hemangioma (pneumocytoma), in a woman 24 years old, asymptomatic, with radiological incidental find. The clinical, imaging and pathological features of the entity are described, with brief bibliographic review.

Optimisation of the imaging and dosimetric characteristics of an electronic portal imaging device employing plastic scintillating fibres using Monte Carlo simulations.

A Monte Carlo model of a novel electronic portal imaging device (EPID) has been developed using Geant4 and its performance for imaging and dosimetry applications in radiotherapy has been characterised. The EPID geometry is based on a physical prototype under ongoing investigation and comprises an array of plastic scintillating fibres in place of the metal plate/phosphor screen in standard EPIDs. Geometrical and optical transport parameters were varied to investigate their impact on imaging and dosimetry performance. Detection efficiency was most sensitive to variations in fibre length, achieving a peak value of 36% at 50 mm using 400 keV x-rays for the lengths considered. Increases in efficiency for longer fibres were partially offset by reductions in sensitivity. Removing the extra-mural absorber surrounding individual fibres severely decreased the modulation transfer function (MTF), highlighting its importance in maximising spatial resolution. Field size response and relative dose profile simulations demonstrated a water-equivalent dose response and thus the prototype's suitability for dosimetry applications. Element-to-element mismatch between scintillating fibres and underlying photodiode pixels resulted in a reduced MTF for high spatial frequencies and quasi-periodic variations in dose profile response. This effect is eliminated when fibres are precisely matched to underlying pixels. Simulations strongly suggest that with further optimisation, this prototype EPID may be capable of simultaneous imaging and dosimetry in radiotherapy.

SU-E-I-109: Sensitivity Analysis of an Electronic Portal Imaging Device Monte Carlo Model to Variations in Optical Transport Parameters.

PURPOSE: To investigate the sensitivity of a Monte Carlo (MC) model of a standard clinical amorphous silicon (a-Si) electron portal imaging device (EPID) to variations in optical photon transport parameters. METHODS: The Geant4 MC toolkit was used to develop a comprehensive model of an indirect-detection a-Si EPID incorporating x-ray and optical photon transport. The EPID was modeled as a series of uniform layers with properties specified by the manufacturer (PerkinElmer, Santa Clara, CA) of a research EPID at our centre. Optical processes that were modeled include bulk absorption, Rayleigh scattering, and boundary processes (reflection and refraction). Model performance was evaluated by scoring optical photons absorbed by the a-Si photodiode as a function of radial distance from a point source of x-rays on an event-by-event basis (0.025 mm resolution). Primary x-ray energies were sampled from a clinical 6 MV photon spectrum. Simulations were performed by varying optical transport parameters and the resulting point spread functions (PSFs) were compared. The optical parameters investigated include: x-ray transport cutoff thresholds; absorption path length; optical energy spectrum; refractive indices; and the 'roughness' of boundaries within phosphor screen layers. RESULTS: The transport cutoffs and refractive indices studied were found to minimally affect resulting PSFs. A monoenergetic optical spectrum slightly broadened the PSF in comparison with the use of a polyenergetic spectrum. The absorption path length only significantly altered the PSF when decreased drastically. Variations in the treatment of boundaries noticeably broadened resulting PSFs. CONCLUSIONS: Variation in optical transport parameters was found to affect resulting PSF calculations. Current work is focusing on repeating this analysis with a coarser resolution more typical of a commercial a-Si EPID to observe if these effects continue to alter the EPID PSF. Experimental measurement of the EPID line spread function to validate these results is also underway. Cancer Institute NSW Research Equipment Grants 10/REG/1-20 and 10/REG/1-10 Cancer Council NSW Grant, ID RG 11-06 NHMRC Project Grant, ID569211 The University of Sydney Postgraduate Research Scholarship in Medical Physics SWSCS Radiation Oncology Student Scholarship, 2012.

Daily online bony correction is required for prostate patients without fiducial markers or soft-tissue imaging.

AIM: To compare online position verification strategies with offline correction protocols for patients undergoing definitive prostate radiotherapy. MATERIALS AND METHODS: We analysed 50 patients with implanted fiducial markers undergoing curative prostate radiation treatment, all of whom underwent daily kilovoltage imaging using an on-board imager. For each treatment, patients were set-up initially with skin tattoos and in-room lasers. Orthogonal on-board imager images were acquired and the couch shift to match both bony anatomy and the fiducial markers recorded. The set-up error using skin tattoos and offline bone correction was compared with online bone correction. The fiducial markers were used as the reference. RESULTS: Data from 1923 fractions were analysed. The systematic error was ≤1 mm for all protocols. The average random error was 2-3mm for online bony correction and 3-5mm for skin tattoos or offline-bone. Online-bone showed a significant improvement compared with offline-bone in the number of patients with >5mm set-up errors for >10% (P<0.001) and >20% (P<0.003) of their fractions. CONCLUSIONS: Online correction to bony anatomy reduces both systematic and random set-up error in patients undergoing prostate radiotherapy, and is superior to offline correction methods for those patients not suitable for fiducial markers or daily soft-tissue imaging.

Obstrucción intestinal por hernia obturatriz: caso clínico / Intestinal obstruction caused by an obturator hernia: report of one case

We report a 76 years old female presenting in the emergency room with a history of abdominal pain lasting seven days. A plain abdominal X ray showed few fluid filled loops. Due to persistence of pain and appearance of vomiting, an abdominal CAT sean showed a short bowel obstruction caused by an obturator hernia. The patient was operated, correcting the defect with a mesh. The postoperative evolution was uneventful.

La hernia obturatriz es una rara causa de obstrucción intestinal, se presenta en pacientes mujeres adultos mayores, desnutridos y postrados; se asocia a una elevada mortalidad por los antecedentes mórbidos de los pacientes y al bajo índice de sospecha. Se recomienda el uso de la tomografía axial computada como técnica de elección para el diagnóstico en pacientes con sospecha clínica. El objetivo de este trabajo es presentar un caso clínico de una paciente con hernia obturatriz que consultó en nuestro servicio de urgencia y se solicitó tomografía de abdomen y pelvis para completar estudio que requirió laparotomía exploradora ante el cuadro clínico y los hallazgos imagenológicos.

Implementation of an image-guided radiation therapy program: Lessons learnt and future challenges.

The aim of this paper is to detail the experience obtained in implementing an image-guided radiation therapy program at the Northern Sydney Cancer Centre. This required retrofitting a Varian Clinac 21EX with an on-board imager. The commissioning and quality assurance procedures, organisation of a multidisciplinary image guided radiation therapy group, and the development of clinical protocols for orthogonal kV and cone beam computed tomography implementation are described. Reassessment of the image-guided radiation therapy program has continued as new equipment and software versions were made available in the department.

Australian & New Zealand Faculty of Radiation Oncology Genito-Urinary Group: 2010 consensus guidelines for definitive external beam radiotherapy for prostate carcinoma.

External beam radiotherapy for prostate cancer has undergone substantial technological and clinical advances in the recent years. The Australian & New Zealand Faculty of Radiation Oncology Genito-Urinary Group undertook a process to develop consensus clinical practice guidelines for external beam radiotherapy for prostate carcinoma delivered with curative intent, aiming to provide guidance for clinicians on the appropriate integration of clinical evidence and newer technologies. Draft guidelines were presented and discussed at a consensus workshop in May 2009 attended by radiation oncologists, radiation therapists and medical physicists. Amended guidelines were distributed to radiation oncologists in Australia, New Zealand and Singapore for comment, and modifications were incorporated where appropriate. Evidence based recommendations for risk stratification, the role of image-guided and intensity-modulated radiation therapy, prescribed dose, simulation and treatment planning, the role and duration of neo-adjuvant/adjuvant androgen deprivation therapy and outcome reporting are presented. Central to the guidelines is the recommendation that image-guided radiation therapy should be used when definitive external beam radiotherapy for prostate cancer is prescribed. The consensus guidelines provide a co-operatively developed, evidence-based framework for contemporary treatment of prostate cancer with external beam radiotherapy.

Síndrome de Rendu-Osler-Weber en paciente adulto: reporte de un caso y revisión de la literatura / Rendu-Osler-Weber syndrome in adult patient: a case report and literature review

El síndrome de Rendu-Osler-Weber es un trastorno hereditario de los vasos sanguíneos, con gran variedad de manifestaciones clínicas que predisponen a fenómenos hemorrágicos (epistaxis, hemorragia digestiva) asociados a telangiectasias en piel y mucosas, acompañados generalmente de anemia ferropriva secundaria. Dichas manifestaciones generalmente subestiman la presencia de otras malformaciones arteriovenosas en órganos como pulmón y cerebro, cuyas complicaciones pueden determinar un riesgo vital para el paciente. La sospecha dada por alguno de los eventos descritos, sumado a la presencia de antecedentes familiares con la misma patología, obligan a realizar la búsqueda activa de malformaciones arteriovenosas en órganos potencialmente afectados para evaluar la posibilidad de un eventual tratamiento, el cual ante cualquier tipo de manifestación, y según avala la literatura, sigue siendo sintomático.

Osler-Weber-Rendu syndrome is an inherited disorder of the vessels, with a great variety of clinical manifestations that predispose to hemorrhage (epistaxis, gastrointestinal bleeding) associated to telangiectasis in skin and mucoses, usually with secondary ferropenic anemia. Those manifestations generally underestimate the presence of other arteriovenous malformations in organs like lungs and brain, where complications are of vital risk for the patient. The suspect given by any of the events described previously, added to the presence of family medical history for the same disorder, make necessary an active search of arteriovenous malformations in potentially affected organs to evaluate the possibility of an eventual treatment, which is for any type of manifestation and according to the literature, still symptomatic.

Molecular characterization of Salmonella isolates by REP-PCR and RAPD analysis.

Eighteen Salmonella isolates from both human and food (non-human) sources (fish, meat, and poultry) were characterized using conventional culture methods, biochemical, serological, and molecular analyses. REP-PCR and RAPD produced DNA profiles for differentiation purposes. Enterobacterial repetitive intergenic consensus (ERIC), repetitive extragenic palindronic (REP) and BOXAIR primers were selected for REP-PCR and two arbitrary primers, namely OPP-16 and OPS-11 were used for RAPD to generate DNA fingerprints from the Salmonella isolates. REP-PCR method showed greater discriminatory power in differentiating closely related strains of the related strains of Salmonella and produced more complex banding patterns as compared with RAPD. A dendogram was constructed with both sets of profiles using SPSS Version 13.0 computer software and showed that most human isolates were separately clustered from the non-human isolates. Two of the human isolates were closely related to some of the non-human isolates. A good correlation was also observed between the serogrouping of the O antigen and the molecular profiles obtained from REP-PCR and RAPD data of the Salmonella isolates. The results of a principal coordinate analysis (PCA) corresponded to the clustering in the dendrogram.

Software tool for portal dosimetry research.

This paper describes a software tool developed for research into the use of an electronic portal imaging device (EPID) to verify dose for intensity modulated radiation therapy (IMRT) beams. A portal dose image prediction (PDIP) model that predicts the EPID response to IMRT beams has been implemented into a commercially available treatment planning system (TPS). The software tool described in this work was developed to modify the TPS PDIP model by incorporating correction factors into the predicted EPID image to account for the difference in EPID response to open beam radiation and multileaf collimator (MLC) transmitted radiation. The processes performed by the software tool include; i) read the MLC file and the PDIP from the TPS, ii) calculate the fraction of beam-on time that each point in the IMRT beam is shielded by MLC leaves, iii) interpolate correction factors from look-up tables, iv) create a corrected PDIP image from the product of the original PDIP and the correction factors and write the corrected image to file, v) display, analyse, and export various image datasets. The software tool was developed using the Microsoft Visual Studio.NET framework with the C# compiler. The operation of the software tool was validated. This software provided useful tools for EPID dosimetry research, and it is being utilised and further developed in ongoing EPID dosimetry and IMRT dosimetry projects.

Radiological properties of the PRESAGE and PAGAT polymer dosimeters.

The radiological properties of the PRESAGE and PAGAT polymer dosimeters have been investigated and their water equivalence determined for use in radiotherapy dosimetry. The radiological water equivalence of each of the polymer dosimeters was determined by comparing the photon and electron interaction cross-sections over the 10 keV-20 MeV energy range and by Monte Carlo modelling the depth dose from a linear accelerator using the BEAMnrc software package. PRESAGE was found to have an effective Z-value and mass density (kgm(-3)) approximately 17% and 10% higher than water, respectively. A maximum difference of 85% was discovered in the photoelectric interaction probability curve of PRESAGE when compared to water over the energy range 10-100 keV, partially due to the Z(3) dependence of the photoelectric effect. The mass radiative stopping power ratios and mass scattering power ratios were both found to have less than 9% difference from water. The depth dose for PRESAGE from a 6MV photon beam had an absolute percentage difference to water of less than 2% and a relative percentage difference of less than 8%. The mass density of PAGAT was found to be 2.6% higher than water due to its high gelatine and monomer concentration. The cross-sectional attenuation and absorption coefficient ratios were found to be within 5% for energies between 10 and 100 keV and within 1% for energies between 100 keV and 20 MeV. The mass collisional stopping power, mass radiative stopping power and mass scattering power ratios were all less than 1% over the energy range studied. The depth dose had an absolute percentage difference to water of less than 1% and a relative percentage difference of less than 2.5%. These results indicate that the PAGAT polymer gel formulation is more radiological water equivalent than the PRESAGE formulation. However, the PRESAGE dosimeter offers some advantages in terms of ease of use and its lack of water equivalence may be overcome with dosimetric correction factors.