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Victor A. Levin, Luis A. Rodriguez, Michael S. B. Edwards, William Wara, Hsiu-Chih Liu, Dorcas Fulton, Richard L. Davis, Charles B. Wilson, and Pamela Silver

adjuvant chemotherapy and may thereby lessen its potential effectiveness. In an attempt to avoid the detrimental effects of craniospinal irradiation and to minimize the myelotoxic effect of chemotherapy in patients with medulloblastoma, a treatment regimen was devised, consisting of administering procarbazine before and hydroxyurea during radiation therapy in conjunction with reduced radiation doses to the spinal axis and whole brain (25 Gy each). The purpose of this study was to determine the effect of such treatment on the incidence of local and distant recurrence

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I. Jonathan Pomeraniec, Davis G. Taylor, Or Cohen-Inbar, Zhiyuan Xu, Mary Lee Vance, and Jason P. Sheehan

neurocognitive side effects. 2 , 22 , 26 , 27 , 43 The long-term incidence of hypopituitarism has been previously investigated, but the etiology of these insufficiencies remains unclear. 2 , 26 , 27 The theoretical and practical advantage of SRS includes targeting a more precise volume of tissue, thereby shielding healthy brain structures from unwanted radiation. This more reliably reduces radiation doses outside of planned target volumes and increases tumor and neuroendocrine control. 14 , 18 , 19 , 21 , 28 , 30 , 48 Despite optimal planning and higher precision, patients

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Bhuvaneswara R. Basina, Claire Olson, Dibyendu Kumar Roy, Chun-Po Yen, David Schlesinger, Kazuki Nagayama, and Jason P. Sheehan

up-front radiation to eloquent brain structures with no radiological evidence of metastatic disease on initial presentation provided that there is a low incidence and/or delayed formation of new tumors in specific neuroanatomical sites. Theoretically, a primary or scattered radiation dose to the hippocampi should be very low during radiosurgery for metastatic brain tumors as long as there is some distance between the lesions and the hippocampi. Admittedly, there is paucity of literature on incidental radiation doses to the hippocampi and ATLs during GKS in patients

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Daniel McDonald, John Schuler, Istvan Takacs, Jean Peng, Joseph Jenrette, and Kenneth Vanek

effective, especially for treating radiosensitive cancers. 10 However, the radiation dose delivered to the normal brain tissues and to radiosensitive organs, such as the optic nerves, limits its use. Studies have shown that the irradiation of normal brain tissues may have undesirable neurocognitive effects, including memory loss. 3 , 23 As a result of an increased recognition of the limitations of WBRT, stereotactic radiosurgery, which allows for precise targeting of brain tumors and spares normal brain tissues, has grown in popularity. While previous methods of

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Single-beam radiotherapy knife

A practical theoretical model

Milton D. Heifetz, Marilyn Wexler, and Ronald Thompson

L eksell's unique cobalt gamma knife is a radiation delivery device consisting of multiple cobalt sources which are focused upon a given small area. 1, 3, 4 Its function is to deliver high doses of radiation to a given preselected small volume of tissue without delivering significant radiation to the adjacent normal tissue. This paper describes a study designed to determine if it is possible to utilize conventional radiation therapy equipment to achieve the same results as Leksell's device. The radiation dose absorbed by a tissue volume is a function of the

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Nicolas Massager, José Lorenzoni, Daniel Devriendt, Françoise Desmedt, Jacques Brotchi, and Marc Levivier

. Until now, no consensus has emerged to define the optimal parameters for this treatment, and different radiation doses and irradiation targets have been proposed. 11 We report here our experience with GKS using a far-anterior target and a high radiation dose for patients suffering from intractable idiopathic TN. Clinical Material and Methods In our institution, three different surgical procedures are offered to patients with drug-resistant TN: microvascular decompression, percutaneous radiofrequency rhizotomy, and GKS. All patients receive extensive information

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Roman Lis˘c˘ák, Vilibald Vladyka, Josef Novotný Jr., Gustav Broz˘ek, Kater˘ina Námĕstková, Vladislav Mares˘, Vít Herynek, Daniel Jirák, Milan Hájek, and Eva Syková

. In all the rats, the caudal parts of the hippocampus were more affected than the rostral segments. The size of the hippocampus was reduced in both the 50- and 75-Gy groups (−18 to −30%) and the pyramidal neurons were hyperchromic. In some rats, there was dilation of capillaries, a pericapillary edema, and distension and deformation of the lateral ventricles. An astrocytic reaction, although not entirely proportional to the radiation dose, was apparent in all these rats. No significant changes in the expression of synapsin and syntaxin, markers of the pre- and

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Roberto Spiegelmann, Zvi Lidar, Jana Gofman, Dror Alezra, Moshe Hadani, and Raphael Pfeffer

superior aspects of the tumor, where the facial nerve, brainstem, and trigeminal nerve, respectively, course. The posteroinferior areas of tumor are occupied by the lateral cerebellum and the inferior cranial nerves, which are resistant to radiation damage. Note the steep radiation falloff beyond the tumor margin. (The distance between the 40% and 16% isodose lines [representing 50% and 20%, respectively, of the therapeutic dose] is 4 mm.) The mean radiation dose directed to the tumor margin was 1455 cGy (range 11–20 Gy). During the first 2 years of the study

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Francesco Costa, Giovanni Tosi, Luca Attuati, Andrea Cardia, Alessandro Ortolina, Marco Grimaldi, Fabio Galbusera, and Maurizio Fornari

, 13 , 21 , 22 , 27 with accuracy in screw placement up to 98.5%. 4 However, despite these encouraging results there is still debate regarding where and when this technology should be used. Specifically, concern exists regarding the overall cost of these technologies, the learning curve, and especially the radiation exposure. Because radiation exposure is a crucial aspect in spine surgery, one of the major criticisms regarding the O-arm system concerns the effective radiation dose. Furthermore, if this device leads to solving the need for real-time detailed

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Michael Synowitz and Juergen Kiwit

P ercutaneous vertebroplasty is an established neurosurgical treatment option for stable fractures of the spine. Biplanar fluoroscopy is mandatory for monitoring and preventing leakage of polymethylmethacrylate into the perivertebral spaces and veins, and requires continuous (pulsed) fluoroscopy with significant ionizing radiation exposure to both the patient and surgeon. There are few publications that address the surgeon’s exposure to radiation during this procedure. 18 , 19 , 22 , 23 , 25 To quantify the effective radiation dose to the operator’s hand