En Bloc Simultaneous Liver-Kidney Transplantation Compared to the Traditional Technique: Results From a Single Center.

BACKGROUND: Simultaneous liver-kidney transplantation is indicated for patients with concomitant end-stage liver disease and end-stage renal disease. The traditional technique involves separate implantations of the liver and the kidney. In the en bloc approach, the liver is recovered en bloc with the right kidney and the donor renal artery is anastomosed to the donor splenic artery. We aimed to compare the outcomes of the traditional and en bloc techniques for simultaneous liver-kidney transplantation in a single center. METHODS: This single-center retrospective study involved all adult patients who underwent simultaneous liver-kidney transplantation from brain-dead donors from January 2017 to December 2022. RESULTS: A total of 15 patients were included: 10 transplanted with the traditional technique and 5 with the en bloc approach. Patients in the en bloc group presented higher body mass index, shorter kidney cold and total ischemia times, shorter overall surgical time and longer kidney warm ischemia time (29.07 kg/m2vs 23.20 kg/m2 [P = .048]; 560 minutes vs 880 minutes [P = .026]; 615 minutes vs 908 minutes [P = 0.025]; 405 minutes vs 485 minutes [P = .046]; 46 minutes vs 33.5 minutes [P = 0.027], respectively). Ureteroneocystostomy was performed in 2 patients of the en bloc group and ureteroureterostomy in the remaining 3 patients. One patient in the en bloc group presented stenosis of renal artery anastomosis and underwent percutaneous angioplasty. This same patient eventually developed late urinary fistula. In the traditional technique group, there were 2 cases of renal vein thrombosis and 1 of ureteral stenosis. CONCLUSIONS: Compared with the traditional technique, the en bloc approach is feasible and safe, reducing kidney total ischemia time and overall surgical time.

Liver Transplantation for Adenomatosis: A Single-Center Experience.

BACKGROUND: Liver adenomatosis is characterized by multiple adenomas diffusely distributed throughout the liver parenchyma. Studies addressing liver transplantation for those cases are scarce, and the criteria used to indicate transplantation are still debatable. OBJECTIVE: To report a single-center experience of liver transplantation for diffuse adenomatosis. METHODS: Single-center retrospective study involving all adult patients who underwent liver transplantation due to adenomatosis from January/2010 to June/2023. RESULTS: A total of 13 patients were identified, corresponding to 0.89% of liver transplants performed during the study period. The mean age was 33 ± 6.55 years, and most of them were female (n = 9, 69.23%). There were 12 transplants with deceased donors and 1 with a right lobe from a living donor. The most frequent reason to preclude liver resection was multiple and large unresectable adenomas in patients without previous liver disease (n = 8, 61.58%), followed by underlying liver disease (Abernethy Malformation, n = 3, 23.07%) and recurrence after liver resection (n = 2, 15.38%). The indications for liver transplantation were high risk of malignant transformation (n = 7, 53.84%), increasing size and number of nodules (n = 3, 23.07%), confirmed malignant transformation (n = 2, 15.38%), and hemorrhage (n = 2, 15.38%). There was 1 perioperative death due to primary non-function. Another patient died during follow-up because of COVID-19. CONCLUSION: Liver adenomatosis is a rare indication for liver transplantation, with acceptable post-transplant outcomes. Unresectable adenomas with high-risk or confirmed malignant transformation are the main indications for transplant. Reasons for unresectability involve underlying liver disease, multiple and large high-risk nodules, and recurrence after previous resection.

Chromatic bleaching and fractionation effects on optically stimulated luminescent dosimeter reuse.

BACKGROUND: Optically stimulated luminescent dosimeters (OSLDs) can be bleached and reused, but questions remain about the effects of repeated bleaching and fractionation schedules on OSLD performance. PURPOSE: The aim of this study was to investigate how light sources with different wavelengths and different fractionation schemes affect the performance of reused OSLDs. METHODS: OSLDs (N = 240) were irradiated on a cobalt-60 beam in different step sizes until they reached an accumulated dose of 50 Gy. Between irradiations they were bleached using light sources of different wavelengths: the Imaging and Radiation Oncology Core (IROC) bleaching system (our control); monochromatic red, green, yellow, and blue lights; and a polychromatic white light. Sensitivity and linearity-based correction factors were determined as a function of dose step-size. The rate of signal removal from different light sources was characterized by sampling these OSLDs at various time points during their bleaching process. Relative doses were calculated according to the American Association of Physicists in Medicine Task Group-191. Signal repopulation was investigated by irradiating OSLDs (N = 300) to various delivered doses of 2, 10, 20, 30, 40, and 50 Gy in a single fraction, bleached with one of the colors, and read over time. Fractionation effects were evaluated by irradiating OSLDs up to 30 Gy in different size steps. After reading, the OSLDs were bleached following IROC protocol. OSLDs (N = 40) received irradiations in 5, 10, 15, 30 Gy fractions until they had an accumulated dose of 30 Gy; The sensitivity response of these OSLDs was compared with reference OSLDs that had no accumulated dose. RESULTS: Light sources with polychromatic spectrums (IROC and white) bleached OSLDs faster than did sources with monochromatic spectra. Polychromatic light sources (white light and IROC system) provided the greatest dose stability for OSLDs that had larger amounts of accumulated dose. Signal repopulation was related to the choice of bleaching light source, timing of bleaching, and amount of accumulated dose. Changes to relative dosimetry were more pronounced in OSLDs that received larger fractions. At 5-Gy fractions and above, all OSLDs had heightened sensitivity, with OSLDs exposed to 30-Gy fractions being 6.4% more sensitive than reference dosimeters. CONCLUSIONS: The choice of bleaching light plays a role in how fast an OSLD is bleached and how much accumulated dose an OSLD can be exposed to while maintaining stable signal sensitivity. We have expanded upon investigations into signal repopulation to show that bleaching light plays a role in the migration of deep traps to dosimetric traps after bleaching. Our research concludes that the bleaching light source and fractionation need to be considered when reusing OSLD.

Technical note: Radiological clinical equivalence for phantom materials in carbon ion therapy.

PURPOSE: As carbon ion radiotherapy increases in use, there are limited phantom materials for heterogeneous or anthropomorphic phantom measurements. This work characterized the radiological clinical equivalence of several phantom materials in a therapeutic carbon ion beam. METHODS: Eight materials were tested for radiological material-equivalence in a carbon ion beam. The materials were computed tomography (CT)-scanned to obtain Hounsfield unit (HU) values, then irradiated in a monoenergetic carbon ion beam to determine relative linear stopping power (RLSP). The corresponding HU and RLSP for each phantom material were compared to clinical carbon ion calibration curves. For absorbed dose comparison, ion chamber measurements were made in the center of a carbon ion spread-out Bragg peak (SOBP) in water and in the phantom material, evaluating whether the material perturbed the absorbed dose measurement beyond what was predicted by the HU-RLSP relationship. RESULTS: Polyethylene, solid water (Gammex and Sun Nuclear), Blue Water (Standard Imaging), and Techtron HPV had measured RLSP values that agreed within ±4.2% of RLSP values predicted by the clinical calibration curve. Measured RLSP for acrylic was 7.2% different from predicted. The agreement for balsa wood and cork varied between samples. Ion chamber measurements in the phantom materials were within 0.1% of ion chamber measurements in water for most materials (solid water, Blue Water, polyethylene, and acrylic), and within 1.9% for the rest of the materials (balsa wood, cork, and Techtron HPV). CONCLUSIONS: Several phantom materials (Blue Water, polyethylene, solid water [Gammex and Sun Nuclear], and Techtron HPV) are suitable for heterogeneous phantom measurements for carbon ion therapy. Low density materials should be carefully characterized due to inconsistencies between samples.

OSLD nanoDot characterization for carbon radiotherapy dosimetry.

Objective. This study characterized optically-stimulated luminescent dosimeter (OSLD) nanoDots for use in a therapeutic carbon beam using the Imaging and Radiation Oncology Core (IROC) framework for remote output verification.Approach. The absorbed dose correction factors for OSLD (fading, linearity, beam quality, angularity, and depletion), as defined by AAPM TG 191, were characterized for carbon beams. For the various correction factors, the effect of linear energy transfer (LET) was examined by characterizing in both a low and high LET setting.Main results. Fading was not statistically different between reference photons and carbon, nor between low and high LET beams; thus, the standard IROC-defined exponential function could be used to characterize fading. Dose linearity was characterized with a linear fit; while low and high LET carbon linearity was different, these differences were small and could be rolled into the uncertainty budget if using a single linearity correction. A linear fit between beam quality and dose-averaged LET was determined. The OSLD response at various angles of incidence was not statistically different, thus a correction factor need not be applied. There was a difference in depletion between low and high LET irradiations in a primary carbon beam, but this difference was small over the standard five readings. The largest uncertainty associated with the use of OSLDs in carbon was because of thekQcorrection factor, with an uncertainty of 6.0%. The overall uncertainty budget was 6.3% for standard irradiation conditions.Significance. OSLD nanoDot response was characterized in a therapeutic carbon beam. The uncertainty was larger than for traditional photon applications. These findings enable the use of OSLDs for carbon absorbed dose measurements, but with less accuracy than conventional OSLD audit programs.

Analysis of Performance and Failure Modes of the IROC Proton Liver Phantom.

Purpose: To analyze trends in institutional performance and failure modes for the Imaging and Radiation Oncology Core's (IROC's) proton liver phantom. Materials and Methods: Results of 66 phantom irradiations from 28 institutions between 2015 and 2020 were retrospectively analyzed. Univariate analysis and random forest models were used to associate irradiation conditions with phantom results. Phantom results included pass/fail classification, average thermoluminescent dosimeter (TLD) ratio of both targets, and percentage of pixels passing gamma of both targets. The following categories were evaluated in terms of how they predicted these outcomes: irradiation year, treatment planning system (TPS), TPS algorithm, treatment machine, number of irradiations, treatment technique, motion management technique, number of isocenters, and superior-inferior extent (in cm) of the 90% TPS isodose line for primary target 1 (PTV1) and primary target 2 (PTV2). In addition, failures were categorized by failure mode. Results: Average pass rate was approximately 52% and average TLD ratio for both targets had slightly improved. As the treatment field increased to cover the target, the pass rate statistically significantly fell. Lower pass rates were observed for Mevion machines, scattered irradiation techniques, and gating and internal target volume (ITV) motion management techniques. Overall, the accuracy of the random forest modeling of the phantom results was approximately 73% ± 14%. The most important predictor was the superior-inferior extent for both targets and irradiation year. Three failure modes dominated the failures of the phantom: (1) systematic underdosing, (2) poor localization in the superior-inferior direction, and (3) range error. Only 44% of failures have similar failure modes between the 2 targets. Conclusion: Improvement of the proton liver phantom has been observed; however, the pass rate remains the lowest among all IROC phantoms. Through various analysis techniques, range uncertainty, motion management, and underdosing are the main culprits of failures of the proton liver phantom. Clinically, careful consideration of the influences of liver proton therapy is needed to improve phantom performance and patient outcome.

Uso del modelador nasolabial (NAM) como tratamiento ortopédico prequirúrgico de paciente con labio y paladar hendido / Use of nasoalveolar molding (NAM) as a pre-surgical orthopedic treatment for patients with cleft lip and palate

Introducción: el labio y paladar hendido es la malformación craneofacial congénita más frecuente y es producida por una falla en la fusión de procesos faciales durante periodos iniciales en el desarrollo embrionario. Objetivo: el objetivo de la ortopedia prequirúrgica es facilitar la primera intervención para la corrección de esta condición de manera que disminuya el trauma quirúrgico, al obtener una menor formación de cicatrices y menor riesgo de complicaciones postquirúrgicas, además de ayudar a obtener una óptima deglución en el paciente para mejorar el aspecto nutricional en el bebé. Material y métodos: el paciente fue llevado a la clínica a las dos semanas de nacido para la toma de impresión y colocación de un aparato ortopédico; se le colocó el NAM (nasoalveolar molding), la cinta transport, además se realizaban citas una vez al mes para evaluar el stent nasal, activarlo y revisar que la colocación de la cinta estuviese correcta, así como para comprobar que la alimentación del bebé estuviera mejorando. Resultados: se observa una mejoría anatómica y fisiológica, también una disminución de la fisura labial de 6 mm y una remodelación nasal. Se notó una mejora en deglución y alimentación con ganancia de peso. Conclusiones: la ortopedia prequirúrgica con el NAM es una terapia aceptable y recomendable para los pacientes con labio y paladar hendido, ya que nos ayudan a generar mejores resultados quirúrgicos, además de colaborar con el aspecto nutricional del bebe (AU)

Introduction: cleft lip and palate is a craniofacial malformation most frequent congenital and is produced by a failure to fuse facial processes during early periods in embryonic development. Objective: the objective of pre-surgical orthopedics is to facilitate the first intervention for the correction of this condition, reducing surgical trauma, obtaining less scar formation and less risk of post-surgical complications, in addition to helping the patient obtain better swallowing to improve the nutritional aspect in the baby. Material and methods: the patient came to the clinic at two weeks of age for impression taking and placement of the orthopedic device. The NAM (nasoalveolar molding) and the transport tape were placed and appointments were made once a month to evaluate the nasal stent, activate it and check that the placement of the tape was correct, as well as to check that the baby's feeding was improving. Results: an anatomical and physiological improvement is observed, as well as a 6mm decrease in the cleft lip and nasal remodeling. An improvement in swallowing and feeding with weight gain was observed. Conclusions: pre-surgical orthopedics with NAM is an acceptable and recommended therapy for patients with cleft lip and palate since it helps us to generate better surgical results in addition to collaborating with the nutritional aspect of the baby (AU)

The current status and shortcomings of stereotactic radiosurgery.

Background: Stereotactic radiosurgery (SRS) is a common treatment for intracranial lesions. This work explores the state of SRS treatment delivery to characterize current treatment accuracy based on treatment parameters. Methods: NCI clinical trials involving SRS rely on an end-to-end treatment delivery on a patient surrogate (credentialing phantom) from the Imaging and Radiation Oncology Core (IROC) to test their treatment accuracy. The results of 1072 SRS phantom irradiations between 2012 and 2020 were retrospectively analyzed. Univariate analysis and random forest models were used to associate irradiation conditions with phantom performance. The following categories were evaluated in terms of how they predicted outcomes: year of irradiation, TPS algorithm, machine model, energy, and delivered field size. Results: Overall, only 84.6% of irradiations have met the IROC/NCI acceptability criteria. Pass rate has remained constant over time, while dose calculation accuracy has slightly improved. Dose calculation algorithm (P < .001), collimator (P = .024), and field size (P < .001) were statistically significant predictors of pass/fail. Specifically, pencil beam algorithms and cone collimators were more likely to be associated with failing phantom results. Random forest modeling identified the size of the field as the most important factor for passing or failing followed by algorithm. Conclusion: Constant throughout this retrospective study, approximately 15% of institutions fail to meet IROC/NCI standards for SRS treatment. In current clinical practice, this is particularly associated with smaller fields that yielded less accurate results. There is ongoing need to improve small field dosimetry, beam modeling, and QA to ensure high treatment quality, patient safety, and optimal clinical trials.

Experimental Clinical Model of Liver Transplantation in Large White Pigs Without Venovenous Bypass: Pre-, Intra-, and Maintenance Care.

BACKGROUND: Liver transplantation in an animal model is challenging due to hemodynamics and intraoperative anesthetic care. Several models are described in the literature employing different techniques such as venovenous bypass or aortic cross-clamping to maintain hemodynamic stability, although few groups keep the animal alive in the postoperative period. This study aims to evaluate a liver transplantation clinical model in pigs without venovenous bypass or aortic cross-clamping. METHODS: Male pigs weighing 20 to 35 kg underwent liver transplantation surgery without using venovenous bypass or aorta cross-clamping. Protocols were approved by the Animal Care and Use Committee of the University of São Paulo, Brazil. RESULTS: Ten LTs were performed. Cold ischemia and warm ischemia were 119 ± 33.28 minutes and 26 ± 9.6 minutes, respectively. Hemodynamic changes were significantly higher after the postrevasculazation phase: heart rate (P < .001), medium arterial pressure (P < .001), and cardiac output (P = .03). Hypotension was treated with intravenous fluids and, in some cases, with vasoactive drugs especially during the post-reperfusion period. No animals died during the procedure and almost survival until the first postoperative day. Serum aspartate aminotransferase and lactate increased their values in the post-reperfusion phase. CONCLUSIONS: Practice-based on laboratory animals improves surgical skills and the development of experimental models aimed at new advances in this field. Perfecting our technique on the swine model, we could move forward to create a small-for-size model, test new therapeutic strategies, and define the boundaries for safely performing an enlarged liver resection or a partial liver graft transplant.

Dosimetric evaluation of irradiation geometry and potential air gaps in an acrylic miniphantom used for external audit of absolute dose calibration for a hybrid 1.5 T MR-linac system.

INTRODUCTION: To investigate the impact of partial lateral scatter (LS), backscatter (BS) and presence of air gaps on optically stimulated luminescence dosimeter (OSLD) measurements in an acrylic miniphantom used for dosimetry audit on the 1.5 T magnetic resonance-linear accelerator (MR-linac) system. METHODS: The following irradiation geometries were investigated using OSLDs, A26 MR/A12 MR ion chamber (IC), and Monaco Monte Carlo system: (a) IC/OSLD in an acrylic miniphantom (partial LS, partial BS), (b) IC/OSLD in a miniphantom placed on a solid water (SW) stack at a depth of 1.5 cm (partial LS, full BS), (c) IC/OSLD placed at a depth of 1.5 cm inside a 3 cm slab of SW/buildup (full LS, partial BS), and (d) IC/OSLD centered inside a 3 cm slab of SW/buildup at a depth of 1.5 cm placed on top of a SW stack (full LS, full BS). Average of two irradiated OSLDs with and without water was used at each setup. An air gap of 1 and 2 mm, mimicking presence of potential air gap around the OSLDs in the miniphantom geometry was also simulated. The calibration condition of the machine was 1 cGy/MU at SAD = 143.5 cm, d = 5 cm, G90, and 10 × 10 cm2 . RESULTS: The Monaco calculation (0.5% uncertainty and 1.0 mm voxel size) for the four setups at the measurement point were 108.2, 108.1, 109.4, and 110.0 cGy. The corresponding IC measurements were 109.0 ± 0.03, 109.5 ± 0.06, 110.2 ± 0.02, and 109.8 ± 0.03 cGy. Without water, OSLDs measurements were ∼10% higher than the expected. With added water to minimize air gaps, the measurements were significantly improved to within 2.2%. The dosimetric impacts of 1 and 2 mm air gaps were also verified with Monaco to be 13.3% and 27.9% higher, respectively, due to the electron return effect. CONCLUSIONS: A minimal amount of air around or within the OSLDs can cause measurement discrepancies of 10% or higher when placed in a high b-field MR-linac system. Care must be taken to eliminate the air from within and around the OSLD.

Recommendations on the practice of calibration, dosimetry, and quality assurance for gamma stereotactic radiosurgery: Report of AAPM Task Group 178.

The American Association of Physicists in Medicine (AAPM) formed Task Group 178 (TG-178) to perform the following tasks: review in-phantom and in-air calibration protocols for gamma stereotactic radiosurgery (GSR), suggest a dose rate calibration protocol that can be successfully utilized with all gamma stereotactic radiosurgery (GSR) devices, and update quality assurance (QA) protocols in TG-42 (AAPM Report 54, 1995) for static GSR devices. The TG-178 report recommends a GSR dose rate calibration formalism and provides tabulated data to implement it for ionization chambers commonly used in GSR dosimetry. The report also describes routine mechanical, dosimetric, and safety checks for GSR devices, and provides treatment process quality assurance recommendations. Sample worksheets, checklists, and practical suggestions regarding some QA procedures are given in appendices. The overall goal of the report is to make recommendations that help standardize GSR physics practices and promote the safe implementation of GSR technologies.

Prevalencia de hiperglicemia y su relación con el tiempo de estadía en un hospital terciario / Association of hyperglycemia with the length of stay in hospitalized patients

Background: Hyperglycemia during hospital stay is associated with adverse outcomes. Aim: To characterize the frequency of hyperglycemia in a tertiary hospital and to correlate it with length of hospital stay (LOS). Material and Methods: Review of medical records of hospitalized patients. Demographic data and laboratory data, previous diabetes mellitus (DM) history, current main diagnosis, unit of hospitalization and the two highest capillary blood glucose values from the analyzed period were recorded for each patient. LOS was obtained from electronic clinical records. Results: 210 subjects, aged 60 ± 19 years (104 women) were included. 113 patients (54%) developed hyperglycemia ≥ 140 mg/L. Thirty one percent of these had a previous history of diabetes and 29% had stress hyperglycemia (SHG). Patients with a history of DM had a higher average blood glucose than those with SHG (238.9 and 178.2 mg/dL, respectively, p < 0.01) and a greater percentage of cases with a blood glucose above 180 mg/dL (72 and 40.0%, respectively, p < 0.01). Hospital LOS was significantly longer in patients with hyperglycemia ≥ 140 mg/dL as compared with those with normoglycemia (29.3 and 12.8 days, respectively, p < 0.01). This association remained significant when introduced in a linear regression analysis including diagnosis, decreased glomerular filtration rate (GFR) and hospitalization unit (p < 0.01). Conclusions: Hyperglycemia during hospitalization affects more than half of hospitalized patients and is associated with a longer length of stay.

Failure Modes in IROC Photon Liver Phantom Irradiations.

PURPOSE: Our purpose was to analyze and classify the patterns of failure for irradiations of the Imaging and Radiation Oncology Core photon liver phantom. METHODS AND MATERIALS: Imaging and Radiation Oncology Core's anthropomorphic liver phantom simulates multitarget liver disease with respiratory motion. Two hundred forty-nine liver phantom results from 2013 to 2019 were analyzed. Phantom irradiations that failed were categorized by the error attributed to the failure. Phantom results were also compared by demographic data, such as machine type, treatment planning system, motion management technique, number of isocenters, and whether the phantom was a first time or repeat irradiation. RESULTS: The failure rate for the liver phantom was 27%. From the 68 irradiations that did not pass, 5 failure modes were identified. The most common failure mode was localization errors in the direction of motion, with over 50% of failures attributed to this mode. The second-most common failure mode was systematic dose errors. The internal target volume technique performed worse than other motion management techniques. Failure modes were different by the number of isocenters used, with multi-isocenter irradiations having more failure modes in a single phantom irradiation. CONCLUSIONS: Motion management techniques and proper alignment of moving targets play a large role in the successful irradiation of the liver phantom. These errors should be examined to ensure accurate patient treatment for liver disease or other sites where multiple moving targets are present.

Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG-55.

The use of radiochromic film (RCF) dosimetry in radiation therapy is extensive due to its high level of achievable accuracy for a wide range of dose values and its suitability under a variety of measurement conditions. However, since the publication of the 1998 AAPM Task Group 55, Report No. 63 on RCF dosimetry, the chemistry, composition, and readout systems for RCFs have evolved steadily. There are several challenges in using the new RCFs, readout systems and validation of the results depending on their applications. Accurate RCF dosimetry requires understanding of RCF selection, handling and calibration methods, calibration curves, dose conversion methods, correction methodologies as well as selection, operation and quality assurance (QA) programs of the readout systems. Acquiring this level of knowledge is not straight forward, even for some experienced users. This Task Group report addresses these issues and provides a basic understanding of available RCF models, dosimetric characteristics and properties, advantages and limitations, configurations, and overall elemental compositions of the RCFs that have changed over the past 20 yr. In addition, this report provides specific guidelines for data processing and analysis schemes and correction methodologies for clinical applications in radiation therapy.

Evaluation of the high definition field of view option of a large-bore computed tomography scanner for radiation therapy simulation.

BACKGROUND AND PURPOSE: Computed tomography (CT) scanning is the basis for radiation treatment planning, but the 50-cm standard scanning field of view (sFOV) may be too small for imaging larger patients. We evaluated the 65-cm high-definition (HD) FOV of a large-bore CT scanner for CT number accuracy, geometric distortion, image quality degradation, and dosimetric accuracy of photon treatment plans. MATERIALS AND METHODS: CT number accuracy was tested by placing two 16-cm acrylic phantoms on either side of a 40-cm phantom to simulate a large patient extending beyond the 50-cm-diameter standard scanning FOV. Dosimetric accuracy was tested using anthropomorphic pelvis and thorax phantoms, with additional acrylic body parts on either side of the phantoms. Two volumetric modulated arc therapy beams (a 15-MV and a 6-MV) were used to cover the planning target volumes. Two-dimensional dose distributions were evaluated with GAFChromic film and point dose accuracy was checked with multiple thermoluminescent dosimeter (TLD) capsules placed in the phantoms. Image quality was tested by placing an American College of Radiology accreditation phantom inside the 40-cm phantom. RESULTS: The HD FOV showed substantial changes in CT numbers, with differences of 314 HU-725 HU at different density levels. The volume of the body parts extending into the HD FOV was distorted. However, TLD-reported doses for all PTVs agreed within ± 3%. Dose agreement in organs at risk were within the passing criteria, and the gamma index pass rate was >97%. Image quality was degraded. CONCLUSIONS: The HD FOV option is adequate for RT simulation and met accreditation standards, although care should be taken during contouring because of reduced image quality.

Compromiso pulmonar por cryptoccus laurentii en paciente inmunocomprometido / Pulmonary Involvement with Cryptococcus Laurentii in an Immunocompromised Patient

La criptococosis afecta predominantemente a pacientes con compromiso de la inmunidad celular. Se presenta el caso de un paciente masculino de 45 años, con antecedentes de VIH y linfoma de Hodgkin, internado por fiebre persistente sin neutropenia. El PET-TC evidenció imágenes hipermetabólicas pulmonares y ganglionares se sospechó recaída de su enfermedad y/o proceso infeccioso. Se realizó BAL, se aisló en cultivo Crytococcus laurentii. Recibió tratamiento con anfotericina B y fluconazol, cultivos de control negativos. Se repitió TC de control sin infiltrados pulmonares y persistencia de adenopatías. Realizó tratamiento con ESHAP evolucionando con buena respuesta.

Cryptococcosis mostly affects patients with cell-mediated immunity involvement. We present the case of a male patient, 45 years old, with history of HIV and Hodgkin's lymphoma, who was admitted to the hospital due to persistent fever without neutropenia. The PET-TC (Positron Emission Tomography - Computed Tomography) showed hypermetabolic pulmonary and lymph node images. We suspected disease relapse and/or the presence of an infectious process. We performed a BAL (Bronchoalveolar Lavage) and Cryptococcus laurentii was isolated in culture. The patient received treatment with amphotericin B and fluconazole, with negative control cultures. The CT control was repeated without pulmonary infiltrates and persistence of adenopathies. The patient received treatment with ESHAP and evolved with good response.

Differences in the Patterns of Failure Between IROC Lung and Spine Phantom Irradiations.

PURPOSE: Our purpose was to investigate and classify the reasons why institutions fail the Imaging and Radiation Oncology Core (IROC) stereotactic body radiation therapy (SBRT) spine and moving lung phantoms, which are used to credential institutions for clinical trial participation. METHODS AND MATERIALS: All IROC moving lung and SBRT spine phantom irradiation failures recorded from January 2012 to December 2018 were evaluated in this study. A failure was a case where the institution did not meet the established IROC criteria for agreement between planned and delivered dose. We analyzed the reports for all failing irradiations, including point dose disagreement, dose profiles, and gamma analyses. Classes of failure patterns were created and used to categorize each instance. RESULTS: There were 158 failing cases analyzed: 116 of 1052 total lung irradiations and 42 of 263 total spine irradiations. Seven categories were required to describe the lung phantom failures, whereas 4 were required for the spine. Types of errors present in both phantom groups included systematic dose and localization errors. Fifty percent of lung failures were due to a superior-inferior localization error, that is, error in the direction of major motion. Systematic dose errors, however, contributed to only 22% of lung failures. In contrast, the majority (60%) of spine phantom failures were due to systematic dose errors, with localization errors (in any direction) accounting for only 14% of failures. CONCLUSIONS: There were 2 distinct patterns of failure between the IROC moving lung and SBRT spine phantoms. The majority of the lung phantom failures were due to localization errors, whereas the spine phantom failures were largely attributed to systematic dose errors. Both of these errors are clinically relevant and could manifest as errors in patient cases. These findings highlight the value of independent end-to-end dosimetry audits and can help guide the community in improving the quality of radiation therapy by focusing attention on where errors manifest in the community.

Reference dosimetry data and modeling challenges for Elekta accelerators based on IROC-Houston site visit data.

PURPOSE: Reference dosimetry data can provide an independent second check of acquired values when commissioning or validating a treatment planning system (TPS). The Imaging and Radiation Oncology Core at Houston (IROC-Houston) has measured numerous linear accelerators throughout its existence. The results of those measurements are given here, comparing accelerators and the agreement of measurement versus institutional TPS calculations. METHODS: Data from IROC-Houston on-site reviews from 2000 through 2014 were analyzed for all Elekta accelerators, approximately 50. For each, consistent point dose measurements were conducted for several basic parameters in a water phantom, including percentage depth dose, output factors, small-field output factors, off-axis factors, and wedge factors. The results were compared by accelerator type independently for 6, 10, 15, and 18 MV. Distributions of the measurements for each parameter are given, providing the mean and standard deviation. Each accelerator's measurements were also compared to its corresponding TPS calculation from the institution to determine the level of agreement, as well as determining which dosimetric parameters were most often in error. RESULTS: Accelerators were grouped by head type and reference dosimetric values were compiled. No class of linac had better overall agreement with its TPS, but percentage depth dose and output factors commonly agreed well, while small-field output factors, off-axis factors, and wedge factors often disagreed substantially from their TPS calculations. CONCLUSION: Reference data has been collected and analyzed for numerous Elekta linacs, which provide an independent way for a physicist to double-check their own measurements to prevent gross treatment errors. In addition, treatment planning parameters more often in error have been highlighted, providing practical caution for physicists commissioning treatment planning systems for Elekta linacs.

Remote beam output audits: a global assessment of results out of tolerance.

BACKGROUND AND PURPOSE: Remote beam output audits, which independently measure an institution's machine calibration, are a common component of independent radiotherapy peer review. This work reviews the results and trends of these audit results across several organisations and geographical regions. MATERIALS AND METHODS: Beam output audit results from the Australian Clinical Dosimetry Services, International Atomic Energy Agency, Imaging and Radiation Oncology Core, and Radiation Dosimetry Services were evaluated from 2010 to the present. The rate of audit results outside a +/-5% tolerance was evaluated for photon and electron beams as a function of the year of irradiation and nominal beam energy. Additionally, examples of confirmed calibration errors were examined to provide guidance to clinical physicists and auditing bodies. RESULTS: Of the 210,167 audit results, 1323 (0.63%) were outside of tolerance. There was a clear trend of improved audit performance for more recent dates, and while all photon energies generally showed uniform rates of results out of tolerance, low (6 MeV) and high (≥18 MeV) energy electron beams showed significantly elevated rates. Twenty nine confirmed calibration errors were explored and attributed to a range of issues, such as equipment failures, errors in setup, and errors in performing the clinical reference calibration. Forty-two percent of these confirmed errors were detected during ongoing periodic monitoring, and not at the time of the first audit of the machine. CONCLUSIONS: Remote beam output audits have identified, and continue to identify, numerous and often substantial beam calibration errors.