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Biomedical subjects

John Adler

Publications and source records attributed to John Adler.

6 recordsLinked to original sources
PubMed2006

Computer aided robotic radiosurgery.

Radiosurgery involves the precise delivery of sharply collimated high-energy beams of radiation to a distinct target volume along selected trajectories. Historically, accurate targeting required the application of a stereotactic frame, thus limiting the use of this procedure to single treatments of selected intracranial lesions. However, the scope of radiosurgery has undergone a remarkable broadening since the introduction of image-guided robotic radiosurgery. Recent developments in real-time image guidance provide an effective frameless alternative to conventional radiosurgery and allow both the treatment of lesions outside the skull and the possibility of performing hypofractionation. As a consequence, targets in the spine, chest and abdomen can now also be radiosurgically ablated with submillimetric precision. Meanwhile, the combination of image guidance, robotic beam delivery, and non-isocentric inverse planning can greatly enhance the conformality and homogeneity of radiosurgery. The aim of this article is to describe the technological basis of image-guided radiosurgery and provide a perspective on future developments. The current clinical usage of robotic radiosurgery will be reviewed with an emphasis on those applications that may represent a major shift in the therapeutic paradigm.

Brain Neoplasms↗
PubMed2004

Ablative procedures for chronic pain.

The advent of neuroaugmentative techniques has reduced the application of neuroablative procedures, especially as regards pain of functional origin. Although intracranial ablative procedures are now rarely performed, spinal ablative procedures, such as anterolateral cordotomies or midline myelotomies, remain important in the management of cancer pain. These procedures produce immediate and satisfactory pain relief with acceptable complication rates. An important future trend will be the application of radiosurgery guided by functional imaging (eg,fMRI, PET) to place such intracranial lesions as cingulotomies or medial thalamotomies.

Catheter Ablation↗
PubMed2004

Respiration tracking in radiosurgery.

Respiratory motion is difficult to compensate for with conventional radiotherapy systems. An accurate tracking method for following the motion of the tumor is of considerable clinical relevance. We investigate methods to compensate for respiratory motion using robotic radiosurgery. In this system the therapeutic beam is moved by a robotic arm, and follows the moving target through a combination of infrared tracking and synchronized x-ray imaging. Infrared emitters are used to record the motion of the patient's skin surface. The position of internal gold fiducials is computed repeatedly during treatment, via x-ray image processing. We correlate the motion between external and internal markers. From this correlation model we infer the placement of the internal target during time intervals where no x-ray images are taken. Fifteen patients with lung tumors have recently been treated with a fully integrated system implementing this new method. The clinical trials confirm our hypothesis that internal motion and external motion are indeed correlated. In a preliminar study we have extended our work to tracking without implanted fiducials, based on algorithms for computing deformation motions and digitally reconstructed radiographs.

Clinical Trials as Topic↗
PubMed2003

Ximelagatran versus warfarin for stroke prevention in patients with nonvalvular atrial fibrillation. SPORTIF II: a dose-guiding, tolerability, and safety study.

OBJECTIVES: We sought to compare the tolerability and safety of three fixed doses of ximelagatran versus warfarin in patients with nonvalvular atrial fibrillation (NVAF). BACKGROUND: Anticoagulants such as warfarin lower the risk of stroke in patients with NVAF. Ximelagatran is a novel, oral direct thrombin inhibitor with predictable pharmacokinetics and no known food or pharmacokinetic drug interactions. METHODS: This was a 12-week, randomized, parallel-group, dose-guiding study of NVAF patients with at least one additional risk factor for stroke. The primary end point was the number of thromboembolic events and bleedings. Three groups received ximelagatran (n = 187) at 20, 40, or 60 mg twice daily, given in a double-blind fashion, without routine coagulation monitoring. In a fourth group, warfarin (n = 67) was managed and monitored according to normal routines, aiming for an International Normalized Ratio of 2.0 to 3.0. RESULTS: A total of 254 patients received study drug. One ischemic stroke (nonfatal) and one transient ischemic attack (TIA) occurred in the ximelagatran group. Two TIAs occurred in the warfarin group. No major bleeds were observed in the ximelagatran group. One major bleed occurred in a warfarin-treated patient. The number of minor and multiple minor bleeds was low, but there was a slight increase by ximelagatran dose. The 60-mg dose resulted in the same number of bleeding events as that with warfarin. S-alanine aminotransferase was increased in eight patients (4.3%) taking ximelagatran, but normalized with continuous treatment or cessation of the drug. CONCLUSIONS: Fixed oral doses of ximelagatran up to 60 mg twice daily were well tolerated, without the need for dose adjustment or coagulation monitoring.

Administration, Oral↗
PubMed2003

Cyberknife radiosurgery for trigeminal neuralgia.

BACKGROUND: We present preliminary results using Cyberknife radiosurgery as a noninvasive treatment for trigeminal neuralgia (TN). METHODS: Ten patients with medically refractory TN who were deemed unsuitable for conventional surgery underwent Cyberknife radiosurgery using CT cisternography for localization. RESULTS: Pain relief was achieved in 7 patients, in 5 of them within 24-72 h after irradiation. CONCLUSION: Cyberknife radiosurgery can achieve early-onset pain relief in a subset of TN patients. Improvements using this technique include the absence of a stereotactic ring, potentially improved targeting accuracy produced by CT cisternography and improved dose homogeneity.

Humans↗