Duración de la diarrea aguda infecciosa con el uso de leche deslactosada vs leche con lactosa en la población pediátrica: Revisión sistemática / Duration of acute infectious diarrhea with the use of lactose-free milk vs. lactose-containing milk in the pediatric population: A systematic review

Introducción: La diarrea aguda es una entidad frecuente en pediatría, constituyendo una de las principales causas de mortalidad en países en desarrollo y en niños menores de cinco años. Si bien la alimentación representa uno de los pilares fundamentales en el tratamiento de la misma, no existe consenso entre los profesionales en cuanto a la indicación de leche deslactosada durante el curso del cuadro. Objetivos: Realizar una revisión sistemática para estudiar el impacto del consumo de leche deslactosada vs leche regular en la duración de la diarrea aguda infecciosa en niños. Materiales y métodos: Se realizó una revisión sistemática incluyendo artículos publicados desde el año 2008 al 2023, utilizando para la búsqueda las bases de datos PubMed, Lillacs, Cochrane Library y literatura gris. Se incluyeron estudios experimentales, observacionales, revisiones, guías de atención y metaanálisis, realizados en pacientes pediátricos sin patologías de base, cursando cuadro de diarrea aguda infecciosa, que compararan el uso de leche deslactosada frente a leche regular. Resultados: Se seleccionaron doce artículos. En 9 de ellos se constató una disminución en la duración de la diarrea en los pacientes que recibieron leche deslactosada con una diferencia de medias de 18 horas (en un rango entre 4 y 32.6 horas). No se reportaron diferencias estadísticamente significativas en la mortalidad entre el uso de una u otra fórmula láctea. En relación al uso de una u otra fórmula no se objetivaron variaciones en el peso estadísticamente significativas. La necesidad de hospitalización fue similar entre ambos grupos. Solo un artículo analizó la frecuencia o volumen de deposiciones sin encontrar diferencias significativas (AU)

Introduction:Acute diarrhea is frequent in pediatrics, and constitutes one of the main causes of mortality in developing countries and in children under five years of age. Although feeding is one of the fundamental pillars in the treatment of diarrhea, there is no consensus among professionals regarding the indication of lactose-free milk during the course of the symptoms. Objectives: To conduct a systematic review to study the impact of lactose-free milk vs. regular milk consumption on the duration of acute infectious diarrhea in children. Materials and methods: A systematic review was conducted including articles published between 2008 and 2023, using PubMed, Lillacs, Cochrane Library databases, and gray literature for the search. Experimental and observational studies, reviews, care guidelines and meta-analysis were included, conducted in pediatric patients without underlying diseases, with acute infectious diarrhea, comparing the use of lactose-free milk versus regular milk. Results: Twelve articles were selected. Nine of them showed a decrease in the duration of diarrhea in patients who received lactose-free milk with a mean difference of 18 hours (ranging from 4 to 32.6 hours). No statistically significant differences in mortality were reported between the use of one or the other milk formula. Regarding the use of one or the other formula, there were no statistically significant variations in weight. The need for hospital admission was similar between the two groups. Only one article analyzed stool frequency or volume with no significant differences (AU)

Design and characterization of a prototype tertiary device for proton beam stereotactic radiosurgery.

Though potentially beneficial, proton beam stereotactic radiosurgery has not been adopted widely secondary to the technical challenge of safely delivering multiple focused beams of proton radiation. In this study, we describe the design and characterization of a proton beam stereotactic radiosurgery system that can be adopted by existing passive scattering systems. This system utilizes a helmet-like device in which patient-specific brass apertures required for final beam collimation are positioned on a scaffold that is separate from the treatment gantry. The proton snout is then fitted with a generic aperture to focus the primary proton beam onto the patient specific apertures that are in the helmet-like device. The patient-specific apertures can all be placed at the start of the treatment, thus treatment with multiple beams can be accomplished without the delay of switching the apertures. In this report we describe a prototype design of this collimation system and dosimetric testing to verify efficacy. Subsequently, we describe a custom 3D printing of a prototype device and report on overall localization accuracy using Winston-Lutz tests. Our results show that it is possible to develop an add-on device for proton beam radiosurgery that is safe and efficient and capable of wide adoption on existing proton delivery systems.

Proton vs Hyperarc™ radiosurgery: A planning comparison.

For many patients, stereotactic radiosurgery (SRS) offers a minimally invasive, curative option when surgical techniques are not possible. To date, the literature supporting the efficacy and safety of SRS treatment techniques uses photon beams. However, with the number of proton therapy facilities exponentially growing and the favorable physical properties of proton beam radiation therapy, there is an opportunity to develop proton therapy techniques for SRS. The goal of this paper is to determine the ability of clinical proton treatment planning systems to model small field dosimetry accurately and to compare various planning metrics used to evaluate photon SRS to determine the optimum beam configurations and settings for proton SRS (PSRS) treatment plans. Once established, these plan settings were used to perform a planning comparison on a variety of different SRS cases and compare SRS metrics between the PSRS plans and HyperArc™ (VMAT) SRS plans.

Etiological periodontal treatment with and without low-level laser therapy on IL-1ß level in gingival crevicular fluid: an in vivo multicentric pilot study.

Cytokine proteins may have important roles during different human physiological and pathological processes. In the oral cavity, the bone loss and periodontal tissue pathology was related to inflammatory process activation. The aim of the present study was to assess the effects of etiological periodontal therapy with and without the use of Low Level Laser Therapy (LLLT) on clinical periodontal parameters and interleukin (IL)-1ß level in gingival crevicular fluid (GCF) from chronic periodontitis (CP) patients. Thirty non-smoker CP patients were selected from the Foggia University Dental Clinic and other 2 private dental clinics. All patients were divided into two homogeneous randomized groups: 15 patients were treated with only scaling and root planing (group 1) and 15 patients with scaling and root planing etiological treatment and LLLT (group 2). In all sites, at baseline before treatment, the periodontal pocket depth (PPD) and bleeding on probing (BOP) were measured. In the PPD sites, the GCF samples were collected from 30 deep (≥5 mm) and shallow (≤3 mm) sites and IL-1ß were evaluated at baseline, after 10 days and 1 month. In all the samples at baseline, the IL-1ß concentration in GCF and BOP rate were significantly higher at deep PPD sites than at the shallow ones. After 10 days in all samples no PPD improvement was observed in the BOP rate but the IL-1 ß level was statistically significantly improved (p<0.005) in group 2 compared to group 1. At 10 days and 1 month, in all deep PPD sites, PPD and BOP improvements were observed. At same time, IL-1ß levels were lower and statistically significantly (p<0.005) improved in group 2 compared to group 1. The results confirmed that the periodontal etiology treatment of deep PPD sites with or with-out associated LLLT promotes periodontal health. Etiological treatment associated with LLLT, improves BOP and inflammation in periodontal disease. Moreover, the IL-1ß concentration changes in GCF suggest these cytokines as a predictable marker of gingival inflammation in chronic periodontitis patients.

The association between three attitude-related indexes of oral hygiene and secondary implant failures: A retrospective longitudinal study.

OBJECTIVE: This study evaluated the strength of the association between three widely used clinical indexes considered as distal behavioural indicators of attitude-related oral status (an index of oral hygiene, the plaque index [PI] and two periodontal indexes, that is the presence of bleeding on probing [BOP] and of pockets probing depth [PPD]) and secondary implant failure due to peri-implantitis in patients rehabilitated with cemented prosthesis. MATERIALS AND METHODS: The study included patients who underwent implant-prosthetic rehabilitation and had joined the programme of maintenance of the same hospital. Implant failures, number of months between implant insertion and implant loading, and patients' surgical protocol were monitored and recorded. Further, PI, BOP and PPD-all attitude-related indicators of oral hygiene and periodontal inflammation-were recorded and related, in terms of odds ratios (ORs ) and corresponding risk factors, to secondary implant failures. RESULTS: A total of 1427 patients (2673 implants) were enrolled. The follow-up ranged from 1.5 to 9 years (mean 5.3 years±1.3). The cumulative survival rate was 98.01%. Thirty-two patients (36 implants, 1.36% of all implants) had implant failure. A statistically significant association between PI, BOP, PPD and secondary failures due to peri-implantitis was observed. CONCLUSION: Within the limitations of this study, all three attitude-related behavioural indicators-the plaque index (PI), bleeding on probing (BOP) and abnormal probing pocket depth (PPD)-proved to be significant risk indicators for secondary implant failure due to peri-implantitis, both from a clinical and from a socio-psychological attitude-related perspective.

Novel MRI and CT compatible stereotactic brain biopsy system in dogs using patient-specific facemasks.

OBJECTIVE: The objective of this pilot study was to describe the application and first preliminary data of a novel MRI and CT compatible patient-specific facemask for stereotactic brain biopsy of intracranial lesions in dogs. METHODS: Five client-owned dogs presenting for neurological deficits consistent with forebrain disease were included in the study. All dogs had MRI findings consistent with an intracranial lesion. Using images obtained from either MRI or CT, a virtual three-dimensional model of each dog's face was generated. The contact surface of each dog's face was selected for facemask design and a target point for biopsy was chosen using specialised software and toolkits. A patient-specific facemask with an attached biopsy port with premeasured and preselected trajectory was then fabricated by a 3D printer. The facemasks were sterilised and used intraoperatively to obtain biopsy samples. Biopsy samples were submitted for both cytological and histopathological evaluation. RESULTS: The diagnostic yield based on specific histological diagnosis was 80%. The one case in which a histological diagnosis could not be confirmed had a cytological interpretation consistent with meningioma. No major complications were observed during or immediately after brain biopsy and all dogs were discharged from the hospital within 72 hours postprocedure. CLINICAL SIGNIFICANCE: In conclusion, patient-specific facemasks appear to be a safe and effective method of brain biopsy in dogs, with minimal complications observed.

Frameless stereotactic radiosurgery for the treatment of primary intracranial tumours in dogs.

Stereotactic radiosurgery (SRS) is a procedure that delivers a single large radiation dose to a well-defined target. Here, we describe a frameless SRS technique suitable for intracranial targets in canines. Medical records of dogs diagnosed with a primary intracranial tumour by imaging or histopathology that underwent SRS were retrospectively reviewed. Frameless SRS was used successfully to treat tumours in 51 dogs with a variety of head sizes and shapes. Tumours diagnosed included 38 meningiomas, 4 pituitary tumours, 4 trigeminal nerve tumours, 3 gliomas, 1 histiocytic sarcoma and 1 choroid plexus tumour. Median survival time was 399 days for all tumours and for dogs with meningiomas; cause-specific survival was 493 days for both cohorts. Acute grade III central nervous system toxicity (altered mentation) occurred in two dogs. Frameless SRS resulted in survival times comparable to conventional radiation therapy, but with fewer acute adverse effects and only a single anaesthetic episode required for therapy.

The effect of temporal HU variations on the uncertainty of dose recalculations performed on MVCT images.

Over the course of radiation therapy, a patient's anatomy may change substantially. The relatively recent addition of frequent in-room imaging to assist with patient localization has provided a database of images that may be used to recalculate dose distributions for adaptive radiotherapy purposes. The TomoTherapy Hi-Art II unit (Accuray Inc., Sunnyvale, CA, USA) uses a helical scanning geometry and a megavoltage (MV) beam to acquire volumetric patient images. This study evaluated the uncertainty of dose calculations performed on megavoltage CT (MVCT) images as a function of temporal Hounsfield Unit (HU) variations observed in the imaging system over three years on two machines. A baseline error between dose calculations performed on kVCT and MVCT images was established using a series of phantoms. This baseline error ranged from -1.4% to 0.6%. Materials of differing densities were imaged and MVCT numbers were measured periodically. The MVCT number of solid water varied from 5 to 103 HU and consistently increased prior to target replacement. Finally, the dosimetric uncertainty of the temporal HU variation was assessed using MVCT images of typical head and neck, lung and prostate cancer patients. Worst-case MVCT recalculation errors could approach 5%, 7% and 10% for the head and neck, lung and prostate images, respectively. However, if a tolerance of ±30 HU were maintained for the MVCT number of solid water, dosimetric errors were limited to ±2.5%, ±3% and ±4%, respectively.

Radiosensitivity and capacity for radiation-induced sublethal damage repair of canine transitional cell carcinoma (TCC) cell lines.

Understanding the inherent radiosensitivity and repair capacity of canine transitional cell carcinoma (TCC) can aid in optimizing radiation protocols to treat this disease. The objective of this study was to evaluate the parameters surviving fraction at 2 Gy (SF(2) ), α/ß ratio and capacity for sublethal damage repair (SLDR) in response to radiation. Dose-response and split-dose studies were performed using the clonogenic assay. The mean SF(2) for three established TCC cell lines was high at 0.61. All the three cell lines exhibited a low to moderate α/ß ratio, with the mean being 3.27. Two cell lines exhibited statistically increased survival at 4 and 24 h in the dose-response assay. Overall, our results indicate that the cell lines are moderately radioresistant, have a high repair capacity and behave similarly to a late-responding normal tissue. These findings indicate that the radiation protocols utilizing higher doses with less fractionation may be more effective for treating TCC.

[Multiple peritrochanteric and pubic calcifications in a young woman on hemodialysis with severe renal osteodystrophy successfully treated with sevelamer+cinacalcet+paracalcitol combination therapy]. / Calcificazioni multiple peritrocanteriche e pubiche in giovane emodializzata con grave osteodistrofia renale risolte dall'associazione sevelamer+cinacalcet+paracalcitolo.

Secondary hyperparathyroidism is a frequent complication of chronic renal failure that can induce severe bone disease and negatively influence the cardiovascular outcome. Therefore, nephrologists should attempt to reach the targets recommended by national and international guidelines using all the available therapeutic strategies. We describe the case of a 37-year-old woman affected by spina bifida and myelomeningocele who had been on hemodialysis since 1993. In July 2006 she developed secondary hyperparathyroidism complicated by peritrochanteric calcifications which did not respond to standard therapy. Because it was impossible to perform a parathyroidectomy, we started medical therapy with a combination of sevelamer hydrochloride, paracalcitol and cinacalcet, which resulted in progressive improvement of laboratory data and osteodystrophy. A diagnosis of mixed secondarytertiary hyperparathyroidism was made, but a progressive increase in iPTH to very high levels suggested a rapid evolution toward a pure tertiary form.

Wernicke's encephalopathy and pancreatic encephalopathy after necrotic-hemorrhagic pancreatitis. A case report.

This case report describes a case of acute necrotic-hemorrhagic pancreatitis complicated by Wernicke's encephalopathy (WE) and stresses the importance of a correct dietetic regimen. A 39-year-old Chinese male patient with negative remote pathological anamnesis was hospitalized in the Medical Department with a diagnosis of gallstones. The clinical course was complicated with the onset of acute pancreatitis. Enteral fasting was imposed with intravenous feeding without vitamin supplementation. The progressive worsening of the clinical, radiodiagnostic and laboratory profile combined with deterioration in the state of consciousness promoted, on the 36th day exploratory laparotomy revealed necrotic-hemorrhagic pancreatitis. The patient was, therefore, admitted to the Intensive Care Unit in a deep coma. The recent medical history, neurological examination, and encephalic computed tomography suggested a revealing diagnosis of WE combined with pancreatic encephalopathy.

[Resistant hypertension and paradox effect in patient with hemodialysis treatment]. / Ipertensione arteriosa resistente con effetto paradosso in corso di trattamento emodialitico sositutivo.

This is a case study of a 65-year-old female, on regular haemodialysis treatment, with resistant hypertension and paradoxical blood pressure (BP) elevation during dialysis. This phenomenon occurs in a small number of patients, since in most patients an acceptable BP is usually reached by adequate control of fluid and volume status with dialysis, sometimes associated with pharmacologic intervention. Since in our patient hypertension persisted despite apparent achievement of dry weight and maintenance of antihypertensive medications, we did some extensive investigations to disclose any secondary causes of hypertension (other than ESRD); we also evaluated whether the optimal dry weight was really achieved and maintained, and if the pharmacokinetics of the antihypertensive drugs was influenced by dialysis. We found no secondary cause of hypertension; by contrast, we detected the presence of a mild cardiac dilatation, and realized that some antihypertensive drugs, taken by our patient, were removed by dialysis. Since both these are known to precipitate the paradoxical BP rise during dialysis, we successfully modified once again our dialysis strategy and changed the antihypertensive therapy, adding a calcium antagonist to both losartan and low-dose minoxidil.

Initial clinical experience with frameless stereotactic radiosurgery: analysis of accuracy and feasibility.

PURPOSE: To report on preliminary clinical experience with a novel image-guided frameless stereotactic radiosurgery system. METHODS AND MATERIALS: Fifteen patients ranging in age from 14 to 81 received radiosurgery using a commercially available frameless stereotactic radiosurgery system. Pathologic diagnoses included metastases (12), recurrent primary intracranial sarcoma (1), recurrent central nervous system (CNS) lymphoma (1), and medulloblastoma with supratentorial seeding (1). Treatment accuracy was assessed from image localization of the stereotactic reference array and reproducibility of biteplate reseating. We chose 0.3 mm vector translation error and 0.3 degree rotation about each axis as the maximum tolerated misalignment before treating each arc. RESULTS: The biteplates were found on average to reseat with a reproducibility of 0.24 mm. The mean registration error from CT localization was found to be 0.5 mm, which predicts that the average error at isocenter was 0.82 mm. No patient treatment was delivered beyond the maximum tolerated misalignment. The radiosurgery treatment was delivered in approximately 25 min per patient. CONCLUSION: Our initial clinical experience with stereotactic radiotherapy using the infrared camera guidance system was promising, demonstrating clinical feasibility and accuracy comparable to many frame-based systems.

Isotropic beam bouquets for shaped beam linear accelerator radiosurgery.

In stereotactic radiosurgery and radiotherapy treatment planning, the steepest dose gradient is obtained by using beam arrangements with maximal beam separation. We propose a treatment plan optimization method that optimizes beam directions from the starting point of a set of isotropically convergent beams, as suggested by Webb. The optimization process then individually steers each beam to the best position, based on beam's-eye-view (BEV) critical structure overlaps with the target projection and the target's projected cross sectional area at each beam position. This final optimized beam arrangement maintains a large angular separation between adjacent beams while conformally avoiding critical structures. As shown by a radiosurgery plan, this optimization method improves the critical structure sparing properties of an unoptimized isotropic beam bouquet, while maintaining the same degree of dose conformity and dose gradient. This method provides a simple means of designing static beam radiosurgery plans with conformality indices that are within established guidelines for radiosurgery planning, and with dose gradients that approach those achieved in conventional radiosurgery planning.

Optically guided intensity modulated radiotherapy.

BACKGROUND AND PURPOSE: Previously, we reported on development of an optically guided system for 3D conformal intracranial radiotherapy using multiple noncoplanar fixed fields. In this paper we report on the extension of our system for stereotactic fractionated radiotherapy to include intensity modulated static ports. METHODS AND MATERIALS: A 3D treatment plan with maximum beam separation is developed in the stereotactic space established by an optically guided system. Gantry angles are chosen such that each beam has a unique entrance and exit pathway, avoids the critical structures, and has a minimal beam's eye view projection. Once, a satisfactory treatment plan is found using this geometric approach an inverse treatment plan is developed using the beam portals established previously. The purpose of adding inverse planing is two fold, on the one hand it allows further reduction of margins around the PTV, while on the other hand it affords the possibility of conformal avoidance of critical structures that are close to or abut the PTV. RESULTS: The use of the optically guided system in conjunction with intensity modulated noncoplanar radiotherapy treatment planning using fixed fields allows the generation of highly conformal treatment plans that exhibit smaller 90, 70, and 50% of prescription dose isodose volumes, improved PITV ratios, comparable or improved EUD, smaller NTD(mean) for the critical structures, and an inhomogeneity index that is within generally accepted limits. CONCLUSION: Because optically guided technology improves the accuracy of patient localization relative to the linac isocenter and allows real-time monitoring of patient position, the planning target volume needs to be corrected only for the limitations of image resolution. Intensity modulated static beam radiotherapy planning then provides the user the ability to further reduce margins on the PTV and to conform very closely to this smaller target volume, and enhances the normal tissue sparing, and high degree of conformality possible with 3D conformal radiotherapy. In addition, since optically guided technology affords improved patient localization and online monitoring of patient position during treatment delivery it allows for safe and efficient delivery of intensity modulated radiotherapy.

Analysis of risk factors associated with radiosurgery for vestibular schwannoma.

OBJECT: The aim of this study was to identify factors associated with delayed cranial neuropathy following radiosurgery for vestibular schwannoma (VS or acoustic neuroma) and to determine how such factors may be manipulated to minimize the incidence of radiosurgical complications while maintaining high rates of tumor control. METHODS: From July 1988 to June 1998, 149 cases of VS were treated using linear accelerator radiosurgery at the University of Florida. In each of these cases, the patient's tumor and brainstem were contoured in 1-mm slices on the original radiosurgical targeting images. Resulting tumor and brainstem volumes were coupled with the original radiosurgery plans to generate dose-volume histograms. Various tumor dimensions were also measured to estimate the length of cranial nerve that would be irradiated. Patient follow-up data, including evidence of cranial neuropathy and radiographic tumor control, were obtained from a prospectively maintained, computerized database. The authors performed statistical analyses to compare the incidence of posttreatment cranial neuropathies or tumor growth between patient strata defined by risk factors of interest. One hundred thirty-nine of the 149 patients were included in the analysis of complications. The median duration of clinical follow up for this group was 36 months (range 18-94 months). The tumor control analysis included 133 patients. The median duration of radiological follow up in this group was 34 months (range 6-94 months). The overall 2-year actuarial incidences of facial and trigeminal neuropathies were 11.8% and 9.5%, respectively. In 41 patients treated before 1994, the incidences of facial and trigeminal neuropathies were both 29%, but in the 108 patients treated since January 1994, these rates declined to 5% and 2%, respectively. An evaluation of multiple risk factor models showed that maximum radiation dose to the brainstem, treatment era (pre-1994 compared with 1994 or later), and prior surgical resection were all simultaneously informative predictors of cranial neuropathy risk. The radiation dose prescribed to the tumor margin could be substituted for the maximum dose to the brainstem with a small loss in predictive strength. The pons-petrous tumor diameter was an additional statistically significant simultaneous predictor of trigeminal neuropathy risk, whereas the distance from the brainstem to the end of the tumor in the petrous bone was an additional marginally significant simultaneous predictor of facial neuropathy risk. The overall radiological tumor control rate was 93% (59% tumors regressed, 34% remained stable, and 7.5% enlarged), and the 5-year actuarial tumor control rate was 87% (95% confidence interval [CI] 76-98%). Analysis revealed that a radiation dose cutpoint of 10 Gy compared with more than 10 Gy prescribed to the tumor margin yielded the greatest relative difference in tumor growth risk (relative risk 2.4, 95% CI 0.6-9.3), although this difference was not statistically significant (p = 0.207). CONCLUSIONS: Five points must be noted. 1) Radiosurgery is a safe, effective treatment for small VSs. 2) Reduction in the radiation dose has played the most important role in reducing the complications associated with VS radiosurgery. 3) The dose to the brainstem is a more informative predictor of postradiosurgical cranial neuropathy than the length of the nerve that is irradiated. 4) Prior resection increases the risk of late cranial neuropathies after radiosurgery. 5) A prescription dose of 12.5 Gy to the tumor margin resulted in the best combination of maximum tumor control and minimum complications in this series.

Calibration of three-dimensional ultrasound images for image-guided radiation therapy.

A new technique of patient positioning for radiotherapy/radiosurgery of extracranial tumours using three-dimensional (3D) ultrasound images has been developed. The ultrasound probe position is tracked within the treatment room via infrared light emitting diodes (IRLEDs) attached to the probe. In order to retrieve the corresponding room position of the ultrasound image, we developed an initial ultrasound probe calibration technique for both 2D and 3D ultrasound systems. This technique is based on knowledge of points in both room and image coordinates. We first tested the performance of three algorithms in retrieving geometrical transformations using synthetic data with different noise levels. Closed form solution algorithms (singular value decomposition and Horn's quaternion algorithms) were shown to outperform the Hooke and Jeeves iterative algorithm in both speed and accuracy. Furthermore, these simulations show that for a random noise level of 2.5, 5, 7.5 and 10 mm, the number of points required for a transformation accuracy better than 1 mm is 25, 100, 200 and 500 points respectively. Finally, we verified the tracking accuracy of this system using a specially designed ultrasound phantom. Since ultrasound images have a high noise level, we designed an ultrasound phantom that provides a large number of points for the calibration. This tissue equivalent phantom is made of nylon wires, and its room position is optically tracked using IRLEDs. By obtaining multiple images through the nylon wires, the calibration technique uses an average of 300 points for 3D ultrasound volumes and 200 for 2D ultrasound images, and its stability is very good for both rotation (standard deviation: 0.4 degrees) and translation (standard deviation: 0.3 mm) transformations. After this initial calibration procedure, the position of any voxel in the ultrasound image volume can be determined in world space, thereby allowing real-time image guidance of therapeutic procedures. Finally, the overall tracking accuracy of our 3D ultrasound image-guided positioning system was measured to be on average 0.2 mm, 0.9 mm and 0.6 mm for the AP, lateral and axial directions respectively.

Ultrasonographic guidance for spinal extracranial radiosurgery: technique and application for metastatic spinal lesions.

OBJECT: The relatively stationary anatomy of the intracranial compartment has allowed the development of stereotactic radiosurgery as an effective treatment option for many intracranial lesions. Difficulty in accurately tracking extracranial targets has limited its development in the treatment of these lesions. The ability to track extracranial structures in real time with ultrasound images allows a system to upgrade and interface pretreatment volumetric images for extracranial applications. In this report the authors describe this technique as applied to the treatment of localized metastatic spinal disease. METHODS: The extracranial stereotactic system consists of an optically tracked ultrasonography unit that can be registered to a linear accelerator coordinate system. Stereotactic ultrasound images are acquired following patient positioning, based on a pretreatment computerized tomography (CT) simulation. The soft-tissue shifts between the virtual CT-based treatment plan and the actual treatment are determined. The degree of patient offset is tracked and used to correct the treatment plan. The ultrasonography-based stereotactic navigation system is accurate to within an approximate means of 1.5 mm based on testing with an absolute coordinate phantom. A radiosurgical treatment was delivered using the system for localization of a metastatic spinal lesion. Compared with the virtual CT simulation, the actual treatment plan isocenter was shifted 12.2 mm based on the stereotactic ultrasound image. The patient was treated using noncoplanar beams to a dose of 15.0 Gy to the 80% isodose shell in a single fraction. CONCLUSIONS: A system for high-precision radiosurgical treatment of metastatic spinal tumors has been developed, tested, and applied clinically. Optical tracking of the ultrasonography probe provides real-time tracking of the patient anatomy and allows computation of the target displacement prior to treatment delivery. The results reported here suggest the feasibility and safety of the technique.

Stereotactic biopsy aided by a computer graphics workstation: experience with 200 consecutive cases.

BACKGROUND: The advent of modern computer technology has made it possible to examine not just the target point, but the entire trajectory in planning for stereotactic biopsies. METHODS: Two hundred consecutive biopsies were performed by one surgeon, utilizing a computer graphics workstation. The target point, entry point, and complete trajectory were carefully scrutinized and adjusted to minimize potential complications. RESULTS: Pathologically abnormal tissue was obtained in 197 cases (98.5%). There was no mortality in this series. Symptomatic hemorrhages occurred in 4 cases (2%). CONCLUSIONS: Computer graphics workstations facilitate safe and effective biopsies in virtually any brain area.