Transcatheter closure of atrial septal defect using intracardiac echocardiography: a two-center, retrospective study.

Aims: We present the experience and long-term results of intracardiac echocardiography (ICE)-guided closure of ostium secundum atrial septal defects (ASDs) in two Italian centers and investigate its systematic applicability as the gold standard in routine clinical practice.

Methods: We retrospectively evaluated all consecutive patients who underwent an ASD percutaneous closure procedure from March 2008 to February 2020. All patients underwent a preprocedural transesophageal echocardiography (TEE) evaluation.

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.

A round-robin gamma stereotactic radiosurgery dosimetry interinstitution comparison of calibration protocols.

Purpose: Absorbed dose calibration for gamma stereotactic radiosurgery is challenging due to the unique geometric conditions, dosimetry characteristics, and nonstandard field size of these devices. Members of the American Association of Physicists in Medicine (AAPM) Task Group 178 on Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance have participated in a round-robin exchange of calibrated measurement instrumentation and phantoms exploring two approved and two proposed calibration protocols or formalisms on ten gamma radiosurgery units. The objectives of this study were to benchmark and compare new formalisms to existing calibration methods, while maintaining traceability to U.

Variable dose interplay effects across radiosurgical apparatus in treating multiple brain metastases.

Purpose: Normal brain tissue doses have been shown to be strongly apparatus dependent for multi-target stereotactic radiosurgery. In this study, we investigated whether inter-target dose interplay effects across contemporary radiosurgical treatment platforms are responsible for such an observation.

Methods: For the study, subsets ([Formula: see text] and 12) of a total of 12 targets were planned at six institutions.

Gamma Knife radiosurgery for sellar and parasellar meningiomas: a multicenter study.

Object: Parasellar and sellar meningiomas are challenging tumors owing in part to their proximity to important neurovascular and endocrine structures. Complete resection can be associated with significant morbidity, and incomplete resections are common. In this study, the authors evaluated the outcomes of parasellar and sellar meningiomas managed with Gamma Knife radiosurgery (GKRS) both as an adjunct to microsurgical removal or conventional radiation therapy and as a primary treatment modality.

A theoretical investigation of optimal target-dose conformity in gamma knife radiosurgery.

Purpose: The purpose of this paper is to suggest guidelines for target-dose conformity in gamma knife stereotactic radiosurgery (GKSRS) by taking into account factors that have been linked to GKSRS complications. We also suggest an explanation for the failure of previous studies to find a correlation between improved conformity index and reduced risk of GKSRS toxicity, where the conformity index, C(S), is defined as the ratio of the prescription volume, V(P), to the target volume, V(T).

Methods: Previous investigations have shown that symptomatic toxicity in GKSRS is correlated with the volume of nontarget tissue receiving the prescription dose, D(P).

Apparatus dependence of normal brain tissue dose in stereotactic radiosurgery for multiple brain metastases.

Object: Technical improvements in commercially available radiosurgery platforms have made it practical to treat a large number of intracranial targets. The goal of this study was to investigate whether the dose to normal brain when planning radiosurgery to multiple targets is apparatus dependent.

Methods: The authors selected a single case involving a patient with 12 metastatic lesions widely distributed throughout the brain as visualized on contrast-enhanced CT.

Prescription dose guideline based on physical criterion for multiple metastatic brain tumors treated with stereotactic radiosurgery.

Purpose: Existing dose guidelines for intracranial stereotactic radiosurgery (SRS) are primarily based on single-target treatment data. This study investigated dose guidelines for multiple targets treated with SRS.

Methods And Materials: A physical model was developed to relate the peripheral isodose volume dependence on an increasing number of targets and prescription dose per target.

A noninvasive eye fixation monitoring system for CyberKnife radiotherapy of choroidal and orbital tumors.

A new noninvasive monitoring system for fixing the eye has been developed to treat orbital and choroidal tumors with CyberKnife-based radiotherapy. This device monitors the eye during CT/MRI scanning and during treatment. The results of this study demonstrate the feasibility of the fixation light system for CyberKnife-based treatments of orbital and choroidal tumors and supports the idea that larger choroidal melanomas and choroidal metastases could be treated with CyberKnife without implanting fiducial markers.

Use of hybrid shots in planning Perfexion Gamma Knife treatments for lesions close to critical structures.

Object: The authors investigated the use of different collimator values in different sectors (hybrid shots) when treating patients with lesions close to critical structures with the Perfexion model Gamma Knife.

Methods: Twelve patients with various tumors (6 with a pituitary tumor, 3 with vestibular schwannoma, 2 with meningioma, and 1 with metastatic lesion) that were within 4 mm of the brainstem, optic nerve, pituitary stalk, or cochlea were considered. All patients were treated at the authors' institution between June 2007 and March 2008.

Whole-procedure clinical accuracy of gamma knife treatments of large lesions.

The mechanical accuracy of Gamma Knife radiosurgery based on single-isocenter measurement has been established to within 0.3 mm. However, the full delivery accuracy for Gamma Knife treatments of large lesions has only been estimated via the quadrature-sum analysis.

Split-volume treatment planning of multiple consecutive vertebral body metastases for cyberknife image-guided robotic radiosurgery.

Cyberknife treatment planning of multiple consecutive vertebral body metastases is challenging due to large target volumes adjacent to critical normal tissues. A split-volume treatment planning technique was developed to improve the treatment plan quality of such lesions. Treatment plans were generated for 1 to 5 consecutive thoracic vertebral bodies (CVBM) prescribing a total dose of 24 Gy in 3 fractions.

Peripheral dose measurement for CyberKnife radiosurgery with upgraded linac shielding.

The authors investigated the peripheral dose reduction for CyberKnife radiosurgery treatments after the installation of a linac shielding upgrade. As in a previous investigation, the authors considered two treatment plans, one for a hypothetical target in the brain and another for a target in the thorax, delivered to an anthropomorphic phantom. The results of the prior investigation showed that the CyberKnife delivered significantly higher peripheral doses than comparable model C Gamma Knife or IMRT treatments.

Effects of residual target motion for image-tracked spine radiosurgery.

A quality assurance method was developed to investigate the effects of residual target motion for hypofractionated spine radiosurgery. The residual target motion (target movement between successive image-guided corrections) was measured on-line via dual x-ray imagers for patients treated with CyberKnife (Accuray, Inc., Sunnyvale, CA), a robotic linear accelerator with intrafractional image-tracking capability.

Image-guided robotic stereotactic body radiotherapy for benign spinal tumors: theUniversity of California San Francisco preliminary experience.

We evaluate our preliminary experience using the Cyberknife Radiosurgery System in treating benign spinal tumors. A retrospective review of 16 consecutively treated patients, comprising 19 benign spinal tumors, was performed. Histologic types included neurofibroma [11], chordoma [4], hemangioma [2], and meningioma [2].

Peripheral dose in ocular treatments with CyberKnife and Gamma Knife radiosurgery compared to proton radiotherapy.

Peripheral radiation can have deleterious effects on normal tissues throughout the body, including secondary cancer induction and cataractogenesis. The aim of this study is to evaluate the peripheral dose received by various regions of the body after ocular treatment delivered with the Model C Gamma Knife, proton radiotherapy with a dedicated ocular beam employing no passive-scattering system, or a CyberKnife unit before and after supplemental shielding was introduced. TLDs were used for stray gamma and x-ray dosimetry, whereas CR-39 dosimeters were used to measure neutron contamination in the proton experiments.

Boosting central target dose by optimizing embedded dose hot spots for gamma knife radiosurgery.

Aims: To develop a boost technique for Gamma Knife radiosurgery by embedding and optimizing dose hot spots inside a conventional Gamma Knife plan.

Methods: An optimization algorithm was developed to automatically arrange the pattern and adjust the intensities of the embedded dose hot spots. We compared the treatment plans of the optimized boost technique with the conventional Gamma Knife treatment plans, where dose hot spots were scattered randomly within the target volume.

Anatomic landmarks versus fiducials for volume-staged gamma knife radiosurgery for large arteriovenous malformations.

Purpose: The purpose of this investigation was to compare the accuracy of using internal anatomic landmarks instead of surgically implanted fiducials in the image registration process for volume-staged gamma knife (GK) radiosurgery for large arteriovenous malformations.

Methods And Materials: We studied 9 patients who had undergone 10 staged GK sessions for large arteriovenous malformations. Each patient had fiducials surgically implanted in the outer table of the skull at the first GK treatment.

Peripheral doses in CyberKnife radiosurgery.

The purpose of this work is to measure the dose outside the treatment field for conformal CyberKnife treatments, to compare the results to those obtained for similar treatments delivered with gamma knife or intensity-modulated radiation therapy (IMRT), and to investigate the sources of peripheral dose in CyberKnife radiosurgery. CyberKnife treatment plans were developed for two hypothetical lesions in an anthropomorphic phantom, one in the thorax and another in the brain, and measurements were made with LiF thermoluminescent dosimeters (TLD-100 capsules) placed within the phantom at various depths and distances from the irradiated volume. For the brain lesion, gamma knife and 6-MV IMRT treatment plans were also developed, and peripheral doses were measured at the same locations as for the CyberKnife plan.

A comparison of Monte Carlo and Fermi-Eyges-Hogstrom estimates of heart and lung dose from breast electron boost treatment.

Purpose: Electrons are commonly used in the treatment of breast cancer primarily to deliver a tumor bed boost. We compared the use of the Monte Carlo (MC) method and the Fermi-Eyges-Hogstrom (FEH) algorithm to calculate the dose distribution of electron treatment to normal tissues.

Methods And Materials: Ten patients with left-sided breast cancer treated with breast-conservation therapy at the University of California, San Francisco, were included in this study.

[Malignant turn of oral planus in three new cases].

The possible malignant potential of oral lichen planus (OLP) is still controversial. We present three new oral lichen planus (OLP) patients who developed oral squamous-cell carcinoma (OSCC). In all cases, were analyzed variables like sex, age, clinical type, localization, extension, follow-up study and treatment, moreover were considered the patient's habits, localization, stage and treatment of cancer.

Checking monitor unit calculations using coordinate transformations to calculate off-axis distances in the collimator frame of reference.

An important part of treatment-planning QA is to check Monitor Units (MUs) calculated by treatment-planning programs. This is generally straightforward, unless the central axis is blocked. One way to check MUs in this case is to select a reference point in the open portion of the field and use the off-axis distance (OAD), as well as other relevant data, to verify the dose.

Comparison of intensity-modulated radiosurgery with gamma knife radiosurgery for challenging skull base lesions.

Purpose: To quantitatively compare intensity-modulated radiosurgery (IMRS) using 3-mm mini-multileaf collimation with gamma knife radiosurgery (GKRS) plans for irregularly shaped skull base lesions in direct proximity to organs at risk (OAR).

Methods And Materials: Ten challenging skull base lesions originally treated with GKRS were selected for comparison with IMRS using inverse treatment planning and 3-mm mini-multileaf collimation operating in step-and-shoot delivery mode. The lesions ranged in volume from 1.

Dose conformity of gamma knife radiosurgery and risk factors for complications.

Purpose: To quantitatively evaluate dose conformity achieved using Gamma Knife radiosurgery, compare results with those reported in the literature, and evaluate risk factors for complications.

Methods And Materials: All lesions treated at our institution with Gamma Knife radiosurgery from May 1993 (when volume criteria were routinely recorded) through December 1998 were reviewed. Lesions were excluded from analysis for reasons listed below.