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.

Automatic detection and segmentation of multiple brain metastases on magnetic resonance image using asymmetric UNet architecture.

Detection of brain metastases is a paramount task in cancer management due both to the number of high-risk patients and the difficulty of achieving consistent detection. In this study, we aim to improve the accuracy of automated brain metastasis (BM) detection methods using a novel asymmetric UNet (asym-UNet) architecture. An end-to-end asymmetric 3D-UNet architecture, with two down-sampling arms and one up-sampling arm, was constructed to capture the imaging features.

Quantifying vascular invasion in pancreatic cancer-a contrast CT based method for surgical resectability evaluation.

Pancreatic cancer (PC) is one of the most lethal cancers, with frequent local therapy resistance and dismal 5-year survival rate. To date, surgical resection remains to be the only treatment option offering potential cure. Unfortunately, at diagnosis, the majority of patients demonstrate varying levels of vascular infiltration, which can contraindicate surgical resection.

Validation of Recursive Partitioning Analysis and Diagnosis-Specific Graded Prognostic Assessment in patients treated initially with radiosurgery alone.

Object: Brain metastases present a therapeutic challenge because patients with metastatic cancers live longer now than in the recent past due to systemic therapies that, while effective, may not penetrate the blood-brain barrier. In the present study the authors sought to validate the Diagnosis-Specific Graded Prognostic Assessment (DS-GPA), a new prognostic index that takes into account the histological characteristics of the primary tumor, and the Radiation Therapy Ontology Group Recursive Partitioning Analysis (RPA) system by using a single-institution database of patients who were treated initially with stereotactic radiosurgery (SRS) alone for brain metastases.

Methods: Investigators retrospectively identified adult patients who had undergone SRS at a single institution, MD Anderson Cancer Center, for initial treatment of brain metastases between 2003 and 2010 but excluded those who had undergone craniotomy and/or whole-brain radiation therapy at an earlier time; the final number was 251.

Predictors of survival in contemporary practice after initial radiosurgery for brain metastases.

Purpose: The number of brain metastases (BM) is a major consideration in determining patient eligibility for stereotactic radiosurgery (SRS), but the evidence for this popular practice is equivocal. The purpose of this study was to determine whether, following multivariate adjustment, the number and volume of BM held prognostic significance in a cohort of patients initially treated with SRS alone.

Methods And Materials: A total of 251 patients with primary malignancies, including non-small cell lung cancer (34%), melanoma (30%), and breast carcinoma (16%), underwent SRS for initial treatment of BM.

Phase 1/2 trial of single-session stereotactic body radiotherapy for previously unirradiated spinal metastases.

Background: In this phase 1/2 study, the authors tested the hypothesis that single-fraction stereotactic body radiotherapy (SBRT) for previously unirradiated spinal metastases is a safe, feasible, and efficacious treatment approach.

Methods: All patients were evaluated by a multidisciplinary team. Spinal magnetic resonance imaging studies were obtained before treatment and at regular intervals to define both target volume and response to treatment.

Generalizable class solutions for treatment planning of spinal stereotactic body radiation therapy.

Purpose: Spinal stereotactic body radiation therapy (SBRT) continues to emerge as an effective therapeutic approach to spinal metastases; however, treatment planning and delivery remain resource intensive at many centers, which may hamper efficient implementation in clinical practice. We sought to develop a generalizable class solution approach for spinal SBRT treatment planning that would allow confidence that a given plan provides optimal target coverage, reduce integral dose, and maximize planning efficiency.

Methods And Materials: We examined 91 patients treated with spinal SBRT at our institution.

Stereotactic body radiation therapy for management of spinal metastases in patients without spinal cord compression: a phase 1-2 trial.

Background: Spinal stereotactic body radiation therapy (SBRT) is increasingly used to manage spinal metastases, yet the technique's effectiveness in controlling the symptom burden of spinal metastases has not been well described. We investigated the clinical benefit of SBRT for managing spinal metastases and reducing cancer-related symptoms.

Methods: 149 patients with mechanically stable, non-cord-compressing spinal metastases (166 lesions) were given SBRT in a phase 1-2 study.

Prospective evaluation of spinal reirradiation by using stereotactic body radiation therapy: The University of Texas MD Anderson Cancer Center experience.

Background: Stereotactic body radiotherapy for previously irradiated, progressive spinal metastases may be a viable option in selected patients. The authors review a prospective series of spinal metastasis patients reirradiated with stereotactic body radiotherapy.

Methods: A total of 59 patients with 63 tumors of the spine were reirradiated with stereotactic body radiotherapy between 2003 and 2009.

Real-time in vivo dosimetry with MOSFET detectors in serial tomotherapy for head and neck cancer patients.

Purpose: A real-time dose verification method using a recently designed metal oxide semiconductor field effect transistor (MOSFET) dosimetry system was evaluated for quality assurance (QA) of intensity-modulated radiation therapy (IMRT).

Methods And Materials: Following the investigation of key parameters that might affect the accuracy of MOSFET measurements (i.e.

A quality assurance procedure to evaluate cone-beam CT image center congruence with the radiation isocenter of a linear accelerator.

A quality assurance (QA) procedure was developed to evaluate the congruence between the cone-beam computed tomography (CBCT) image center and the radiation isocenter on a Varian Trilogy linac. In contrast to the published QA procedures, this method did not require a ball bearing (BB) phantom to be placed exactly at the radiation isocenter through precalibrated room lasers or light field crosshairs. The only requirement was that the BB phantom be in a stationary position near the radiation isocenter during the image acquisition process.

Apparatus-dependent dosimetric differences in spine stereotactic body radiotherapy.

The purpose of this investigation was to study apparatus-dependent dose distribution differences specific to spine stereotactic body radiotherapy (SBRT) treatment planning. This multi-institutional study was performed evaluating an image-guided robotic radiosurgery system (CK), intensity modulated protons (IMP), multileaf collimator (MLC) fixed-field IMRT with 5 mm (11 field), 4 mm (9 field), and 2.5 mm (8- and 9-field) leaf widths and intensity modulated volumetric arc therapy (IMVAT) with a 2.

Pretreatment verification of IMSRT using electronic portal imaging and Monte Carlo calculations.

The use of an amorphous silicon electronic portal imaging device (EPID) and Monte Carlo calculations were investigated for pretreatment fluence verification in intensity modulated stereotactic radiotherapy (IMSRT). Monte Carlo calculations were performed using BEAM, a general purpose Monte Carlo code to simulate radiation beams from radiotherapy units. The dose distribution to the EPID phosphor was calculated by BEAM and then converted to pixel value using a pixel calibration curve.

Neurocognition in patients with brain metastases treated with radiosurgery or radiosurgery plus whole-brain irradiation: a randomised controlled trial.

Background: It is unclear whether the benefit of adding whole-brain radiation therapy (WBRT) to stereotactic radiosurgery (SRS) for the control of brain-tumours outweighs the potential neurocognitive risks. We proposed that the learning and memory functions of patients who undergo SRS plus WBRT are worse than those of patients who undergo SRS alone. We did a randomised controlled trial to test our prediction.

Advances in technology for intracranial stereotactic radiosurgery.

Stereotactic radiosurgery (SRS) refers to a single radiation treatment delivering a high dose to an intra-cranial target localized in three-dimensions by CT and/or MRI imaging. Traditionally, immobilization of the patient's head has been achieved using a rigid stereotactic head frame as the key step in allowing for accurate dose delivery. SRS has been delivered by both Cobalt-60 (Gamma Knife) and linear accelerator (linac) technologies for many decades.

Management of spinal metastases from renal cell carcinoma using stereotactic body radiotherapy.

Purpose: To evaluate the outcomes associated with stereotactic body radiotherapy (SBRT) in the management of spinal metastases from renal cell carcinoma (RCC).

Methods And Materials: SBRT was used in the treatment of patients with spinal metastases from RCC. Patients received either 24 Gy in a single fraction, 27 Gy in three fractions, or 30 Gy delivered in five fractions.

Dosimetric effect of translational and rotational errors for patients undergoing image-guided stereotactic body radiotherapy for spinal metastases.

Purpose: To investigate the dosimetric effects of translational and rotational patient positioning errors on the treatment of spinal and paraspinal metastases using computed tomography image-guided stereotactic body radiotherapy. The results of this study provide guidance for the treatment planning process and recognition of the dosimetric consequences of daily patient treatment setup errors.

Methods And Materials: The data from 20 patients treated for metastatic spinal cancer using image-guided stereotactic body radiotherapy were investigated in this study.

Field-in-field technique with intrafractionally modulated junction shifts for craniospinal irradiation.

Purpose: To plan craniospinal irradiation with "field-in-field" (FIF) homogenization in combination with daily, intrafractional modulation of the field junctions, to minimize the possibility of spinal cord overdose.

Methods And Materials: Lateral cranial fields and posterior spinal fields were planned using a forward-planned, step-and-shoot FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction.

Phase I/II study of stereotactic body radiotherapy for spinal metastasis and its pattern of failure.

Object: The authors report data concerning the safety, effectiveness, and patterns of failure obtained in a Phase I/II study of stereotactic body radiotherapy (SBRT) for spinal metastatic tumors.

Methods: Sixty-three cancer patients underwent near-simultaneous computed tomography-guided SBRT. Spinal magnetic resonance imaging was conducted at baseline and at each follow-up visit.

Stereotactic radiosurgical treatment of cerebral metastases arising from breast cancer.

Objective: This study was undertaken to evaluate the outcome of patients undergoing stereotactic radiosurgery (SRS) as primary or salvage treatment of brain metastases arising from breast cancer.

Materials And Methods: Between July 2000 and September 2005, the medical records of 49 breast cancer patients who underwent SRS for 84 brain metastases were reviewed retrospectively. Thirty-four patients received SRS as primary brain metastasis treatment and 15 patients received SRS as salvage treatment of brain metastasis recurrence following prior whole-brain radiation therapy.

Automatic target localization and verification for on-line image-guided stereotactic body radiotherapy of the spine.

To facilitate image-guided stereotactic body radiotherapy (IG-SBRT) of spinal and paraspinal tumors, the authors have developed an on-line image registration system for automated target localization and patient position verification with high precision. When rotations are present in a patient's daily setup position, a setup error of a few millimeters can be introduced in localization of the isocenter by using surrounding bony structures. This setup error not only will deteriorate the dose coverage of the tumor, more importantly it will overdose the spinal cord.

A pilot study of neurocognitive function in patients with one to three new brain metastases initially treated with stereotactic radiosurgery alone.

Objective: Whether to administer or omit adjuvant whole-brain radiation therapy in conjunction with stereotactic radiosurgery (SRS) in the initial management of patients with one to three newly diagnosed brain metastases is the subject of debate. This report provides data from a pilot study in which neurocognitive function (NCF) was prospectively measured for patients with one to three newly diagnosed brain metastases treated with initial SRS alone.

Methods: Fifteen patients were prospectively treated with initial SRS alone.

Case-control study of stereotactic radiosurgery for recurrent glioblastoma multiforme.

Object: The role of stereotactic radiosurgery (SRS) for recurrent glioblastoma multiforme (GBM) was evaluated in a case-control study.

Methods: All patients who underwent SRS for recurrent GBM before March 2003 formed the case group. A control group of patients who did not undergo SRS was created from an institutional database, and each case was matched for known prognostic factors in GBM.

Phase I clinical evaluation of near-simultaneous computed tomographic image-guided stereotactic body radiotherapy for spinal metastases.

Purpose: To evaluate in a Phase I study the safety, feasibility, and patient-positioning accuracy of treating patients with intensity-modulated, near-simultaneous, computed tomographic (CT) image-guided stereotactic body radiotherapy (SBRT).

Patients And Methods: Fifteen consecutive patients with metastatic spinal disease who met protocol eligibility criteria were entered into a Phase I clinical trial. Each patient received five treatments of intensity-modulated, near-simultaneous CT image-guided SBRT, for a total of 75 treatments with 90 isocenter setups during the course of the study.