bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimentally determined three-dimensional dose distributions in small complex targets
Authors: Mack Andreas , Wolff Robert , Weltz Dirk , Mack Günther , Jess Anja , Heck Bernd , Czempiel Heinz , Kreiner Hans-Jürg , Wowra Berndt , Böttcher Heinz , Seiffert Volker
Published: November 2018

Object. The purpose of the paper is to describe a workable three-dimensional dosimetry system for use in quality assurance programs of departments in which radiosurgery is performed.

Methods. A system was developed on the basis of radiochromatic films. The experimental findings of the measured dose distributions for small complex-shaped targets, within a specially designed phantom, are described and compared with the same parameters calculated from the corresponding dose plan. The following parameters were determined for 83 patients with irregularly shaped targets who underwent gamma knife radiosurgery (GKS): target volume; dose—volume histograms of the target; 12-Gy, 15-Gy, and 18-Gy volumes; dose plan conformity; dose fall profiles in all dimensions to 50% of the prescription dose; and a quality factor (QF) to evaluate the adequacy of a GKS plan or treatment.

The precise function and accuracy of the developed measuring device is shown and it demonstrated the expected steep dose falloff outside the irregularly shaped targets in all directions. The dose falloff was of the order of > 3 Gy/mm and the values of the QF were in the range between 0.5 and 0.9.

Conclusions. A comparison with data from the literature shows that at least for small targets (< 2 cm3 and < 2.5 cm3) simulated within a head phantom, the dose gradient is significantly steeper in all directions than when using alternative treatment devices in radiosurgery and the overall QF is superior in most of the cases.
Application of polymer gel dosimetry in gamma knife radiosurgery
Authors: Novotný Josef , Novotný Josef , Spĕvác˘ek Václav , Dvor˘ák Pavel , Cechák Tomás˘ , Lis˘c˘ák Roman , Broz˘ek Gustav , Tintĕra Jaroslav , Vymazal Josef
Published: November 2018

Object. The purpose of this study was to investigate the use of a polymer gel—based dosimeter for the evaluation of geometric and dosimetric inaccuracies during gamma knife radiosurgery and during the irradiation of an experimental animal.

Methods. A polymer gel dosimeter, based on acrylic monomers, was used for experiments conducted in this study. The accuracy of the dosimeter was evaluated on a Siemens EXPERT 1-tesla scanner in the transmitter/receiver head coil with the use of a multiecho sequence with 16 echoes, TE 22.5 to 360 msec, TR 2000 msec, slice thickness 2 mm, field of view 255 mm, and a pixel size of 0.5 × 0.5 mm2. Two experiments were conducted. First, the head phantom containing the polymer gel dosimeter was irradiated using 4-, 8-, 14-, and 18-mm isocenters. Second, a specially designed rat phantom was irradiated by four 4-mm isocenters. The dose profiles in the x, y, and z axes were calculated in the treatment planning system and measured with the polymer gel dosimeter and the results were compared.

There was good agreement between the measured and calculated dose profiles. The maximum deviation in the spatial position of the center of measured and calculated dose profiles was 0.5 mm in the head phantom and 1 mm in the rat phantom. The maximum deviation in the width of the selected reference isodose of measured profiles was 1.2 mm in the head phantom and 1.1 mm in the rat phantom.

Conclusions. The use of the polymer gel—based dosimeter for the verification of stereotactic procedures has advantages compared with other dosimetric systems. The dosimeter itself is tissue equivalent. Three-dimensional dose distributions can be measured and the dosimeter allows simulation of the therapeutic procedures.
Rotational movements of the Automatic Positioning System under load and their significance for patient treatments
Authors: Walton Lee , Hampshire Anna , Brownett Christopher , Soanes Tracy , Vaughan Paul , Rowe Jeremy , Radatz Matthias , Kemeny Andras
Published: November 2018

Object. During routine quality assurance (QA) testing of the gamma knife Automatic Positioning System (APS), it was noticed that slight pressure applied to the handle of the QA test tool produced visible rotation of the APS assembly. The authors describe the tests performed to quantify these movements.

Methods. A stereotactic frame was positioned in the slides of the APS and known loads applied using a spring balance to the upper corner of the frame. Movement at the corner of the frame (y = 200) was measured using a dial gauge. The typical load applied to the APS by a patient with a medium-sized head was determined in a treatment simulation. Projecting the measured data, a plot showing the resultant error in the position of a target point was constructed. Error values increased with distance from the frame, up to a maximum of 0.3 mm (at the superior limit of treatment range). Increased loads could be applied to the system during patient movements, and these would result in larger displacements. Two volunteers enlisted to simulate patient movements and the deflections were recorded. It was estimated that maximum errors in the target positioning of 0.45 mm might take place during these movements.

Conclusions. The use of the APS has some additional and unexpected associated errors. The authors believe, however, that because the errors are smaller than those of target localization and manual trunnion treatments, its clinical use is still justified. The manufacturer is investigating the cause of the movements and possible solutions.
Gamma knife radiosurgery for craniopharyngiomas: longterm results in the first Swedish patients
Authors: Úlfarsson Elfar , Lindquist Christer , Roberts Maud , Rähn Tiit , Lindquist Melker , Thorén Marja , Lippitz Bodo
Published: November 2018

Object. The purpose of this study was to assess the long-term treatment efficacy and morbidity of patients who undergo gamma knife radiosurgery (GKS) for craniopharyngioma.

Methods. Twenty-one consecutive Swedish patients were evaluated retrospectively: 11 children (≤ 15 years) and 10 adults. The time from diagnosis to the most recent follow-up imaging study was 6.3 to 34.3 years (mean 18.2 years, median 16.8 years). Tumor volumes and morbidity from GKS or other treatments were assessed at the time of the most recent imaging study or at the time of a subsequent new treatment. The observation period ranged from 0.5 to 29 years (mean 7.5 years, median 3.5 years). The prescription dose ranged from less than 3 Gy to 25 Gy. The mean tumor volume was 7.8 cm3 (range 0.4–33 cm3).

There were 22 tumors in 21 patients treated with GKS. Five of these tumors were reduced in size, three were unchanged, and 14 increased. Tumor progression correlated with a low dose to the tumor margin. Eleven (85%) of 13 tumors that received a dose of less than 6 Gy to the margin increased in size, whereas only three (33%) of nine tumors that received 6 Gy increased. This difference was statistically significant (p = 0.01). In five of six patients tumors that became smaller after GKS there were no recurrences within a mean follow-up period of 12 years. Nine (82%) of 11 tumors in children ultimately increased after GKS, compared with five (50%) of 10 in adults. In eight patients there was a deterioration of visual function. In all except one this could be related to a volume increase but radiation-induced damage could not be excluded as a factor in any of them. Four patients developed pituitary deficiencies.

Conclusions. Gamma knife radiosurgery is effective in controlling growth of craniopharyngiomas with a minimum dose of 6 Gy. The findings also suggest that other stereotactic techniques, such as cyst aspiration and intracystic treatment, are only of value in reducing tumor volume in preparation for safe GKS.
Gamma knife radiosurgery in patients with advanced breast cancer undergoing bone marrow transplant
Authors: Levin Kenneth J. , Youssef Emad F. , Sloan Andrew E. , Patel Rajiv , Zabad Rana K. , Zamorano Lucia
Published: November 2018

Object. Recent studies have suggested a high incidence of cognitive deficits in patients undergoing high-dose chemotherapy, which appears to be dose related. Whole-brain radiotherapy (WBRT) has previously been associated with cognitive impairment. The authors attempted to use gamma knife radiosurgery (GKS) to delay or avoid WBRT in patients with advanced breast cancer treated with high-dose chemotherapy and autologous bone marrow transplantation (HDC/ABMT) in whom brain metastases were diagnosed.

Methods. A retrospective review of our experience from 1996 to 2001 was performed to identify patients who underwent HDC/ABMT for advanced breast cancer and brain metastasis. They were able to conduct GKS as initial management to avoid or delay WBRT in 12 patients following HDC/ABMT. All patients were women. The median age was 48 years (range 30–58 years). The Karnofsky Performance Scale score was 70 (range 60–90). All lesions were treated with a median prescription dose of 17 Gy (range 15–18 Gy) prescribed to the 50% isodose.

Median survival was 11.5 months. Five patients (42%) had no evidence of central nervous system disease progression and no further treatment was given. Four patients were retreated with GKS and three of them eventually received WBRT as well. Two patients were treated with WBRT as the primary salvage therapy. The median time to retreatment with WBRT was 8 months after the initial GKS.

Conclusions. Gamma knife radiosurgery can be effectively used for the initial management of brain metastases to avoid or delay WBRT in patients treated previously with HDC, with acceptable survival and preserved cognitive function.
Optimal timing for Gamma Knife surgery after hemorrhage from brain arteriovenous malformations
Authors: Maruyama Keisuke , Koga Tomoyuki , Shin Masahiro , Igaki Hiroshi , Tago Masao , Saito Nobuhito
Published: November 2018

Object

Optimal timing of Gamma Knife surgery (GKS) after hemorrhage from brain arteriovenous malformations (AVMs) is unclear and of concern to neurosurgeons because GKS is usually performed after absorption of the hematoma. The authors investigated whether waiting for hematoma absorption is beneficial and aimed to clarify the optimal treatment timing.

Methods

The authors retrospectively studied 211 patients with AVMs who presented with hemorrhage and underwent GKS as the initial treatment. Patients were categorized into 3 groups according to the interval between the time of first hemorrhage and GKS, as follows: Group 1, 0–3 months (70 patients); Group 2, 3–6 months (62 patients); and Group 3, > 6 months (79 patients). The obliteration rates, number of hemorrhages before and after GKS, and complication rates were compared between these 3 groups. The authors also analyzed a subgroup of 127 patients who presented with intracerebral hemorrhage (ICH) to identify the influence of ICH on outcome.

Results

After a median follow-up of 6.3 years, the rates of obliteration, hemorrhage after treatment, and complication were not significantly different between the 3 groups even though the patients with a longer interval before GKS (Group 3) had more AVMs in eloquent areas and neurological deficits. However, the numbers of patients with preoperative hemorrhage in the interval before GKS was significantly higher in Group 3 (1, 3, and 20 patients in Group 1, 2, and 3, respectively). These results were similar in the analyses of 127 patients presenting with ICH.

Conclusions

No benefit was detected in waiting for hematoma absorption until GKS after hemorrhage from AVM. Because of higher hemorrhagic risk until GKS > 6 months after hemorrhage, the authors recommend GKS within 6 months after hemorrhage.
Gamma Knife surgery in the management of radioresistant brain metastases in high-risk patients with melanoma, renal cell carcinoma, and sarcoma
Authors: Powell John W. , Chung Chung T. , Shah Hemangini R. , Canute Gregory W. , Hodge Charles J. , Bassano Daniel A. , Liu Lizhong , Mitchell Lisa , Hahn Seung S.
Published: November 2018

Object

The purpose of this study was to examine the results of using Gamma Knife surgery (GKS) for brain metastases from classically radioresistant malignancies.

Methods

The authors retrospectively reviewed the records of 76 patients with melanoma (50 patients), renal cell carcinoma (RCC; 23 patients), or sarcoma (3 patients) who underwent GKS between August 1998 and July 2007. Overall patient survival, intracranial progression, and local progression of individual lesions were analyzed.

Results

The median age of the patients was 57 years (range 18–85 years) and median Karnofsky Performance Scale (KPS) score was 80 (range 20–100). Sixty-two patients (81.6%) had uncontrolled extracranial disease. A total of 303 intracranial lesions (average 3.97 per patient, range 1–27 lesions) were treated using GKS. More than 3 lesions were treated in 30 patients (39.5%). Median GKS tumor margin dose was 18 Gy (range 8–30 Gy). Thirty-seven patients (48.7%) underwent whole brain radiation therapy. The actuarial 12-month rate for freedom from local progression for individual lesions was 77.7% and was significantly higher for RCC compared with melanoma (93.6 vs 63.0%; p = 0.001). The percentage of coverage of the prescribed dose to target volume was the only treatment–related variable associated with local control: 12-month actuarial rate of freedom from local progression was 71.4% for lesions receiving ≥ 90% coverage versus 0.0% for lesions receiving < 90% (p = 0.00048). Median overall survival was 5.1 months after GKS and 8.4 months after the discovery of brain metastases. Univariate analysis revealed that KPS score (p = 0.000004), recursive partitioning analysis class (p = 0.00043), and single metastases (p = 0.028), but not more than 3 metastases, to be prognostic factors of overall survival. The KPS score remained significant after multivariate analysis. Overall survival for patients with a KPS score ≥ 70 was 7.1 months compared with 1.3 months for a KPS score ≤ 60 (p = 0.013).

Conclusions

Gamma Knife surgery is an effective treatment option for patients with radioresistant brain metastases. In this setting, KPS score appeared to be a more important factor in predicting survival than having > 3 metastases. Higher rates of local tumor control were achieved for RCC in comparison with melanoma, and this may have an effect on survival in some patients. Although outcomes generally remained poor in this study population, these results suggest that GKS can be considered as a treatment option for many patients with radioresistant brain metastases, even if these patients have multiple lesions.
Retreatment of vestibular schwannomas with Gamma Knife surgery
Authors: Dewan Sheri , Norén Georg
Published: November 2018

Object

The response rate of vestibular schwannomas (VSs) to radiosurgery has reached the 97% level in several published series. When failure rarely occurs, some controversy has existed as to whether the tumor has to be resected or can be safely retreated with radiosurgery. The authors retrospectively studied the outcome of retreating 11 patients with Gamma Knife surgery (GKS).

Methods

The authors studied 11 patients at the New England Gamma Knife Center who had undergone GKS as a second radiosurgical treatment for VS from 1994 to 2007. One patient underwent proton-beam radiotherapy as the first treatment, and the other 10 patients had undergone GKS initially. Tumor control (size before and after the first and the second treatment) was evaluated using MR imaging to demonstrate the course after the 2 treatments. Facial nerve function (House–Brackmann grading system), trigeminal nerve function, hearing (Gardner–Robertson classification), and any adverse radiation effects were evaluated. The prescription dose was 12 Gy (11–13.2 Gy) for both treatments.

Results

Of the 11 patients, 2 showed increase, 1 had no change, and, in 8, the VS decreased in size after the retreatment. One tumor remained unchanged over the first 6 months, but demonstrated signs of internal necrosis. All patients demonstrated stable facial nerve function. Regarding facial numbness, 2 patients experienced increases, 8 no change, and 1 decreased numbness. There was no functional hearing prior to the second treatment in 10 patients, and hearing was impaired in 1 patient. Adverse radiation effects (slight peduncular edema) were seen in 2 patients after the second treatment, and 1 patient had edema after the first treatment as well.

Conclusions

Vestibular schwannomas can be retreated with GKS with good tumor control response and low risk of toxicity.
Clinical outcomes after Gamma Knife surgery for idiopathic trigeminal neuralgia: review of 76 consecutive cases
Authors: Dellaretti Marcos , Reyns Nicolas , Touzet Gustavo , Sarrazin Thierry , Dubois François , Lartigau Eric , Blond Serge
Published: November 2018

Object

Stereotactic radiosurgery is an increasingly used, and the least invasive, surgical option for patients with trigeminal neuralgia (TN). In this study, the authors performed a retrospective evaluation of the safety and efficacy of this method for idiopathic TN.

Methods

The authors reviewed data from 76 patients with idiopathic TN who underwent Gamma Knife surgery (GKS). The mean age of the patients was 64 years (range 27–83 years). All patients had typical features of TN. Thirty patients (39.5%) had previously undergone surgery. The intervention consisted of GKS on the retrogasserian cisternal portion of the fifth cranial nerve. The mean maximum GKS dose used was 85.1 Gy (range 75–90 Gy).

Results

Patients were followed-up from 6 to 42 months (mean 20.3 months) after GKS. Complete pain relief was achieved in 83.1% of the patients within 1 year, 70.9% within 2 years, and 62.5% within 3 years. Patients who underwent previous surgery demonstrated a lower rate of pain relief (p < 0.05). Twenty patients (26.3%) reported pain recurrence between 6 and 42 months after treatment. New or worsened persistent trigeminal dysfunction developed after GKS in 16 patients (21%); 8 of these patients described some facial numbness/not bothersome, and 8 reported some facial numbness/somewhat bothersome. None of the patients developed troublesome dysesthesia or anesthesia dolorosa.

Conclusions

Gamma Knife surgery for idiopathic TN proved to be safe and effective and was associated with a particularly low rate of complications.
Low-grade gliomas treated by fractionated gamma knife surgery
Authors: Simonová Gabriela , Novotny Josef , Liscák Roman
Published: November 2018

Object. The authors sought to evaluate local tumor control, complications, and progression-free survival in patients harboring low-grade gliomas who were treated with Leksell gamma knife surgery (GKS).

Methods. During a 6-year period 70 patients were treated for verified low-grade gliomas (Grade I or II) by GKS. Statistical analysis was based on 68 patients; two patients were lost to follow up. The median patient age was 17 years. The median target volume was 4200 mm.3 The median prescription dose was 25 Gy. The median number of fractions was five. Ninety-five percent of patients were treated in five daily fractions.

Partial or complete tumor regression was achieved in 83% of patients with a median time to response of 18 months. There was moderate acute or late toxicity in not more than 5% of patients. In this series the progression-free survival was 92% at 3 years and 88% at 5 years.

Conclusions. Relatively high local tumor control with minimal complications was achieved.
Gamma knife surgery for hypothalamic hamartomas accompanied by medically intractable epilepsy and precocious puberty: experience in Mexico
Authors: Barajas Marco A. , G. Ramírez-Guzmán Maria , Rodríguez-Vázquez Carlos , Toledo-Buenrostro Vinicio , Cuevas-Solórzano Abel , Rodríguez-Hernández Gabriel
Published: November 2018

Object. Hypothalamic hamartoma is a nonneoplastic malformative mass of neurons and glia in the region of the hypothalamus. Because of its location, open surgery is associated with high morbidity and mortality rates. Gamma knife surgery (GKS) may be an efficient and safe treatment approach, which produces little morbidity. The authors describe the results of GKS in three patients with hypothalamic hamartomas.

Methods. All patients were male, aged 3, 12, and 15 years. The lesions were classified according to the Valdueza scale: one was Type IIb and two were Type IIa. The patients presented with gelastic seizures (15–20 per day), generalized epilepsy, behavioral abnormalities, and alterations of the sleep cycle. Precocious puberty was present in one patient. The Type IIb tumor had a volume of 1.8 cm3, and the Type IIa tumors were 597 mm3 and 530.1 mm3. The lesions received 12.5 Gy, 14 Gy, and 15 Gy, respectively, to the 50% isodose line. The patients were followed for 30 to 50 months. After 3 months, all patients showed improvement of their sleep, behavior, and epilepsy. At the present time, these patients are receiving low-dose antiepileptic agents and have achieved adequate social development and school integration.

Conclusions. Gamma knife surgery appears to be a good, safe, and effective option for the treatment of selected hypothalamic hamartomas. No morbidity or mortality was associated with these three cases.
Targeting the cranial nerve: microradiosurgery for trigeminal neuralgia with CISS and 3D-Flash MR imaging sequences
Authors: Zerris Vasilios A. , Noren Georg C. , Shucart William A. , Rogg Jeff , Friehs Gerhard M.
Published: November 2018

Object. The authors undertook a study to identify magnetic resonance (MR) imaging techniques that can be used reliably during gamma knife surgery (GKS) to identify the trigeminal nerve, surrounding vasculature, and areas of compression.

Methods. Preoperative visualization of the trigeminal nerve and surrounding vasculature as well as targeting the area of vascular compression may increase the effectiveness of GKS for trigeminal neuralgia. During the past years our gamma knife centers have researched different MR imaging sequences with regard to their ability to visualize cranial nerves and vascular structures. Constructive interference in steady-state (CISS) fusion imaging with three-dimensional gradient echo sequences (3D-Flash) was found to be of greatest value in the authors' 25 most recent patients.

In 24 (96%) out of the 25 patients, the fifth cranial nerve, surrounding vessels, and areas of compression could be reliably identified using CISS/3D-Flash. The MR images were acceptable despite patients' history of microvascular decompression, radiofrequency (RF) ablation, or concomitant disease. In one of 25 patients with a history of multiple RF lesions, the visualization was inadequate due to severe trigeminal nerve atrophy.

Conclusions. The CISS/3D-Flash fusion imaging has become the preferred imaging method at the authors' institutions during GKS for trigeminal neuralgia. It affords the best visualization of the trigeminal nerve, surrounding vasculature, and the precise location of vascular compression.
Outpatient gamma knife surgery for vestibular schwannoma: definition of the therapeutic profile based on a 10-year experience
Authors: Wowra Berndt , Muacevic Alexander , Jess-Hempen Anja , Hempel John-Martin , Müller-Schunk Stefanie , Tonn Jörg-Christian
Published: November 2018

Object. The purpose of the study was to define the therapeutic profile of outpatient gamma knife surgery (GKS) for vestibular schwannoma (VS) by using sequential tumor volumetry to quantify changes following treatment.

Methods. A total of 111 patients met the inclusion criteria. The median follow-up duration was 7 years (range 5–9.6 years). Thirty-seven patients (33%) had undergone surgery before GKS and 10 (9%) had neurofibromatosis Type 2 (NF2). The median VS volume was 1.6 cm3 (range 0.08–8.7 cm3).

The actuarial 6-year tumor control rate after a single GKS treatment was 95%. Tumor swelling was observed in 43 patients (38.7%). Recurrence was significantly associated with NF2 (p < 0.003) and the reduced dose (p < 0.03) delivered to these tumors. The incidence of facial nerve neuropathy was mainly determined by surgery prior to GKS (p < 0.0001). Facial nerve radiation toxicity was mild and transient. No permanent facial nerve toxicity was observed. Trigeminal neuropathy occurred in 13 patients, and this was correlated with the VS volume (p < 0.02). The median hearing loss was −10 dB (range + 20 dB to −70 dB). The risk of hearing loss was correlated with age and transient tumor swelling (p < 0.05) but not with dose parameters or NF2.

Conclusions. Outpatient GKS is feasible, effective, and safe. Its therapeutic profile compares favorably with that of microsurgery.
Gamma knife surgery for brain metastases from lung cancer
Authors: Pan Hung-Chuan , Sheehan Jason , Stroila Matei , Steiner Melita , Steiner Ladislau
Published: November 2018

Object. The authors conducted a study to evaluate the safety and efficacy of gamma knife surgery (GKS) for the treatment of brain metastases from lung cancer.

Methods. Between February 1993 and May 2003 191 patients underwent treatment for 424 brain metastases from non—small (171 cases) and small cell lung carcinoma (20 cases). Imaging and clinical status were monitored every 3 months following the treatment. Kaplan-Meier survival curves, Cox proportional hazards regression for risk factor analysis, and nonparametric methods for evaluating tumor response were used.

There was no difference in median survival following combined whole-brain radiation therapy (WBRT) and gamma knife surgery (14 months) and GKS alone (15 months). There was also no difference between the median survival rates for either tumor type. In the multivariate analysis, age less than 65 years, Karnofsky Performance Scale score greater than 70, normal neurological status, multiple GKS treatments, and pre-GKS craniotomy were related to longer survival.

Tumor control rates varied according to the volume of the metastases and were as follows: 84.4% (< 0.5 cm3), 94% (0.5–2 cm3), 89.1% (2–4 cm3), 93.4% (4–8 cm3), 85.7% (8–14 cm3), and 87.5% (> 14 cm3). Four lesions required post-GKS craniotomy due to swelling or rapid tumor progression. The rate of tumor shrinkage was higher when a volume was 2 cm3, lower in cystic lesions, lower in tumors with previous WBRT, and lower for margin doses less than 14 Gy.

Conclusions. The risk—benefit ratio of GKS in this series was satisfactory. There was no difference in response rates of the two tumor types, and WBRT did not improve the duration of survival.
Gamma knife surgery for brain metastases in patients harboring four or more lesions: survival and prognostic factors
Authors: Nam Taek-Kyun , Lee Jung-Il , Jung Young-Jo , Im Yong-Seok , An Hee-Ye , Nam Do-Hyun , Park Kwan , Kim Jong-Hyun
Published: November 2018

Object. This study was performed to evaluate the role of gamma knife surgery (GKS) in patients with a large number (four or more) of metastatic brain lesions.

Methods. The authors retrospectively reviewed the outcome in 130 patients who underwent GKS for metastatic lesions. Eighty-four patients presented with one to three lesions (Group A) and 46 presented with four or more lesions (Group B). The overall median survival time after GKS was 35 weeks. The median survival time in Group A (48 weeks) was significantly longer (p = 0.005) than the survival time in Group B (26 weeks). The recursive partitioning analysis (RPA) class was the only significant prognostic factor identified in multivariate analysis. The median survival for patients in RPA Classes I, II, and III was 72, 48, and 19 weeks, respectively, in Group A and 36 and 13 weeks for Classes II and III in Group B. The number of lesions, tumor volume, whole brain radiotherapy, primary tumor site, age, and sex did not affect survival significantly.

Conclusions. It is suggested that GKS provides an increase in survival time even in patients with a large number (four or more) of metastatic lesions. Concerning the selection of patients for GKS, RPA class should be considered as the most important factor and multiplicity of the lesions alone should not be a reason for withholding GKS.
Progress in glaucoma treatment research: a nonrandomized prospective study of 102 patients with advanced refractory glaucoma treated by Leksell gamma knife irradiation
Authors: Vladyka Vilibald , Lis˘c˘ák R. , S˘imonová G. , Pilbauer J. , Hejduková I. , Novác˘ek L.
Published: November 2018

Object. The authors performed a study to characterize the effects of ciliary body gamma knife surgery (GKS) for advanced glaucoma.

Methods. In addition to a pilot project involving 14 patients, 88 other patients were treated. Four 8-mm isocenters were used. Blind eyes received 20 Gy to the 50% isodose. If there was preserved vision the dose was 15 Gy. The median follow up was 20 months (range 2–54 months).

Severe pain was present in 93% of patients with secondary glaucoma; after GKS it was substantially improved in 89% of cases. In primary open angle glaucoma, the pain was less frequent and severe. In more than half the patients it disappeared during a median latency of 6 weeks. The median intraocular pressure value was lowered in patients with secondary glaucoma (from 51.3–27 mm Hg). The same values for primary glaucoma were 25.3 and 16.1 mm Hg, respectively, after a median latency of 12 weeks. Twenty-seven of 40 patients with neovascular glaucoma showed a marked reduction of neovascularization after a median latency of 18 weeks. Treatment complications were slight. There was postoperative lacrimation in 61%. Two patients underwent postirradiation cataract extraction. Noninfectious keratitis was observed in two patients. Pharmacotherapy could be reduced in all patients and ceased in approximately one third. There has been no recurrence of the initial symptoms and no worsening of visual acuity.

Conclusions. Gamma knife surgery ameliorates the main symptoms in advanced glaucomas and precludes the need for eventual ocular enucleation.
Gamma knife thalamotomy for movement disorders: evaluation of the thalamic lesion and clinical results
Authors: Ohye Chihiro , Shibazaki Tohru , Sato Sumito
Published: November 2018

Object. The authors studied the effects of gamma knife thalamotomy (GKT) on Parkinson disease-related tremor and essential tremor before and after reloading of radioactive cobalt.

Methods. Based on experience in stereotactic thalamotomy aided by depth microrecording, the target was located at the lateral border of the thalamic ventralis intermedius nucleus (VIM). For more precise targeting, the percentage representation of the thalamic VIM in relation to the entire thalamic length is useful. The location of the target was determined on magnetic resonance (MR) imaging and computerized tomography scanning. A maximum dose of 130 Gy was delivered to the target by using a single isocenter with the 4-mm collimator. In more recent cases, a systematic follow-up examination was performed at 3, 6, 12, 18, and 24 months after GKT.

Since 1993, the authors have treated 70 patients with PD. Throughout the series the same dosimetric technique has been used. The course after GKT was compared between the 25 cases with PD treated before reloading and the 35 cases treated after reloading. In the majority (80–85%) treated after reloading, tremor and rigidity were reduced around 6 months after GKT. In the cases treated before reloading this effect took approximately 1 year. The thalamic reaction on MR imaging showed the same two lesion types in both series: a restricted and a diffuse. After reloading the restricted lesion was more frequent and the lesion volume was smaller.

Conclusions. The shorter delay in clinical improvement and smaller lesion size may be related to an increased radiation dose.
Prolonged survival in a subgroup of patients with brain metastases treated by gamma knife surgery
Authors: Yu C. P. , Cheung Joel Y. C. , Chan Josie F. K. , Leung Samuel C. L. , Ho Robert T. K.
Published: November 2018

Object. The authors analyzed the factors involved in determining prolonged survival (≥ 24 months) in patients with brain metastases treated by gamma knife surgery (GKS).

Methods. Between 1995 and 2003, a total of 116 patients underwent 167 GKS procedures for brain metastases. There was no special case selection. Smaller and larger lesions were treated with different protocols. The mean patient age was 56.9 years, the mean number of initial lesions was 3.15, and the mean lesion volume was 10.45 cm.3 The mean follow-up time was 9.2 months.

The median patient survival was 8.68 months. One-, 2-, 3-, 4-, and 5-year actuarial survival rates were 31.8%, 19.8%, 14.6%, 7.7%, and 6.9%, respectively. Patient age, number of lesions at presentation, and lesion volume had no influence on patient survival. Twenty-three (19.8%) patients survived for 24 months or more. Certain factors were associated with increased survival time. These were stable primary disease (21 of 23 patients), a long latency between diagnosis of the primary tumor and the occurrence of brain metastases (mean 28.4 months, median 16 months), absence of third-organ involvement, and repeated local procedures. Ten patients underwent repeated GKS (mean 3.4 per patient). Seven patients required open surgery for local treatment failures (recurrence or radiation necrosis). Two patients had both. Fifteen patients underwent repeated procedures.

Conclusions. Aggressive local therapy with GKS, repeated GKS, and GKS plus surgery can achieve increased survival in a subgroup of patients with stable primary disease, no third-organ involvement, and long primary-brain secondary intervals.
Gamma Knife surgery for low-grade astrocytomas: evaluation of long-term outcome based on a 10-year experience
Authors: Wang Ling-Wei , Shiau Cheng-Ying , Chung Wen-Yuh , Wu Hsiu-Mei , Guo Wan-Yuo , Liu Kang-Du , Ho Donald Ming-tak , Wong Tai-Tong , Pan David Hung-Chi
Published: November 2018

Object

The authors report the long-term treatment results of Gamma Knife surgery (GKS) for patients with low-grade astrocytomas who underwent surgery at a single institution.

Methods

A series of 21 patients (median age 20 years) with 25 intracranial low-grade astrocytomas (World Health Organization Grades I and II) were treated with GKS between 1993 and 2003. Among them, four underwent GKS as a primary treatment. Two underwent GKS as a treatment boost after radiotherapy. In the other 15 patients, GKS was performed as an adjuvant or salvage treatment for residual/recurrent tumors after the patients had undergone craniotomy. Tumor volumes ranged from 0.2 to 13.3 ml (median 2.4 ml). Prescription margin doses ranged from 8 to 18 Gy (median 14.5 Gy). Radiation volumes were 1.3 to 21.6 ml (median 3.6 ml). Patients underwent regular follow up, with neurological evaluation and magnetic resonance imaging studies obtained at 6-month intervals.

One patient was lost to follow-up. The clinical follow-up time was 5 to 144 months (median 67 months). Complete tumor remission was seen in three patients. The 10-year progression-free patient survival rate after GKS was 65%. Tumor progression was found in six patients of whom five received further salvage treatment. All the tumor progression occurred within the GKS-treated volumes. Mild-to-moderate adverse radiation effects (AREs) were found in eight patients. Both of the patients who had undergone GKS as a treatment boost after radiotherapy developed AREs, but with good shrinkage of tumors.

Conclusions

Gamma Knife surgery provides durable long-term local tumor control with acceptable toxicity for some patients with highly selected low-grade astrocytomas.
A simple dose gradient measurement tool to complement the conformity index
Authors: Paddick Ian , Lippitz Bodo
Published: November 2018

✓A dose gradient index (GI) is proposed that can be used to compare treatment plans of equal conformity. The steep dose gradient outside the radiosurgical target is one of the factors that makes radiosurgery possible. It therefore makes sense to measure this variable and to use it to compare rival plans, explore optimal prescription isodoses, or compare treatment modalities.

The GI is defined as the ratio of the volume of half the prescription isodose to the volume of the prescription isodose. For a plan normalized to the 50% isodose line, it is the ratio of the 25% isodose volume to that of the 50% isodose volume.

The GI will differentiate between plans of similar conformity, but with different dose gradients, for example, where isocenters have been inappropriately centered on the edge of the target volume.

In a retrospective series of 50 dose plans for the treatment of vestibular schwannoma, the optimal prescription isodose was assessed. A mean value of 40% (median 38%, range 30–61%) was calculated, not 50% as might be anticipated. The GI can show which of these prescription isodoses will give the steepest dose falloff outside the target.

When planning a multiisocenter treatment, there may be a temptation to place some isocenters on the edge of the target. This has the apparent advantage of producing a plan of good conformity and a predictable prescription isodose; however, it risks creating a plan that has a low dose gradient outside the target. The quality of this dose gradient is quantified by the GI.
Unilateral Holmes tremor and focal dystonia after Gamma Knife surgery
Authors: Chiou Thomas S. M. , Tsai Chon-Haw , Lee Ying-Hsuan
Published: November 2018

✓Holmes tremor is a rare, involuntary slow shaking in the proximal portions of the limbs during rest and voluntary motion. It occurs frequently after midbrain damage. The authors report on a 20-year-old man who developed Holmes tremor after undergoing Gamma Knife surgery for an arteriovenous malformation in the left thalamus extending to the tegmentum. This is possibly the first report of such an adverse effect after radiosurgery. The tremor was believed to be secondary to radiation-induced infarction of the midbrain.
Gamma Knife surgery for the management of intracranial dural arteriovenous fistulas
Authors: Wu Hsiu-Mei , Pan David Hung-Chi , Chung Wen-Yuh , Guo Wan-Yuo , Liu Kang-Du , Shiau Cheng-Ying , Wang Ling-Wei , Chen Shih-Jen
Published: November 2018

Object

The purpose of this study was to assess the efficacy and safety of Gamma Knife surgery (GKS) for the treatment of cavernous sinus dural arteriovenous fistulas (CSDAVFs) and other intracranial dural arteriovenous fistulas (ODAVFs).

Methods

Among the 238 GKS procedures performed for intracranial DAVFs in the authors' institute, 227 cases (146 CSDAVFs and 81 OIDAVFs) with clinical follow up formed the database from which the authors determined clinical outcome and the incidence of untoward events. One hundred ninety-five cases (118 CSDAVFs and 77 ODAVFs) with imaging follow up formed the database from which the authors determined the imaging results.

Older age, female sex, higher incidence of diabetes, and shorter duration of symptoms were noted more in cases of CSDAVF than in ODAVFs. Most patients had symptomatic improvement after GKS. A symptomatic cure was observed in one patient with CSDAVFs as early as 6 weeks. The cumulative cure rate based on follow-up angiography of CSDAVFs approached 75% at 24 months, which was much better than that of ODAVFs (approximately 50% at 24 months). A neuroimaging-based cure lagged behind that of the clinical symptoms. Overall, there were only two nonfatal intracerebral hemorrhages during the follow-up period, both occurring less than 1 week after GKS and both being Cognard Type IIa+b with initial aggressive symptoms. Transient deterioration of neurological status without hemorrhage was noted in six patients with ODAVFs. Thrombosis of the superior ophthalmic vein occurred in 11 patients with CSDAVFs, in two of whom there were unilateral visual impairments. There were three cranial nerve neuropathies: transient in one CSDAVF and one ODAVF involving the jugular foramen, and another one was a CSDAVF previously treated by conventional radiotherapy.

Conclusions

Gamma Knife surgery provides a safe and effective option for treatment of intracranial DAVFs with a low risk of complications. In cases of DAVFs with benign clinical presentation, GKS can serve as a primary treatment. In some cases of aggressive DAVFs in which there is extensive retrograde cortical vein drainage, combined treatment with embolization or surgery is suggested.
Ommaya reservoir placement followed by Gamma Knife surgery for large cystic metastatic brain tumors
Authors: Yamanaka Yuji , Shuto Takashi , Kato Yoriko , Okada Tomu , Inomori Shigeo , Fujino Hideyo , Nagano Hisato
Published: November 2018

Object

The combination approach of Ommaya reservoir placement and Gamma Knife surgery (GKS) was evaluated for the treatment of large cystic metastatic brain tumors.

Methods

The medical records of 22 patients harboring 28 tumors, who underwent Ommaya reservoir placement followed by GKS for large cystic metastatic brain tumors were retrospectively reviewed. The patients' ages ranged 26 to 77 years (mean 57.1 years). The most common locations of primary malignancy were the breast (11 patients) followed by the lung (seven patients). The mean maximum diameter of the tumor was 40.1 mm before Ommaya reservoir placement and 31.2 mm at GKS (mean reduction of 19.9%). The mean calculated tumor volume at GKS was 13.4 cm3. The mean tumor margin dose was 16 Gy in 17 patients treated by GKS only and 11 Gy in five patients treated using both GKS and external radiotherapy. The mean follow-up period was 11.5 months. Nineteen (67.9%) of the 28 tumors were controlled. The median patient survival time was 7 months. Asymptomatic intracystic hemorrhage associated with Ommaya reservoir placement was seen in two patients with four tumors, but no serious complication occurred.

Conclusions

Ommaya reservoir placement followed by GKS is relatively effective and safe for large cystic metastatic brain tumors. Gamma Knife surgery should be performed within a few days of Ommaya reservoir placement. Reaccumulation and high viscosity of cystic content must be considered.
Entre dentelle et fragment : évolution de la tactique du vide rimbaldienne de la Saison aux Illuminations
Authors: Hammoudi Rafika
Published: November 2018

"A Season in Hell" and "Illuminations" both of these collections are considered as masterpieces of Rimbaud’s poetry. Whereas "A Season in Hell" is presented as his artistic testimony, "Illuminations", on the other hand, isconsidered by critics as an abstruse writing, an enigma. Acknowledging critical inheritance on this topic, as well as inherent differences of both collections, this article will show that a link could be found between these two works. This thread, which creates what we would like to call Rimbaud’s embrodery was created by himself through silence and words. That is this will of Rimbaud for these bothsworks and readers, that we will discuss here, a strategy that we have named : Tactic of Emptiness.
El archivo de la Dirección Federal de Seguridad: una fuente para escribir la historia de la segunda mitad del siglo XX mexicano
Authors: Naymich López Macedonio Mónica
Published: November 2018

El archivo de la Dirección Federal de Seguridad (DFS) no es solo el archivo de la Guerra Sucia. Se trata de una fuente imprescindible para reconstruir una historia de México más amplia. Este artículo tiene el propósito de mostrar algunas de las posibilidades de investigación logradas a partir de ese acervo, que nos dejan ver el amplio horizonte y la complejidad de los actores sociales y políticos de la segunda mitad del siglo XX; un periodo que hasta hace poco más de una década parecía inédito para los historiadores en México, porque había sido explorado y tratado, principalmente, por la audacia de aquellos que ejercen el periodismo como profesión.
INTEGRAL TRANSFORMATION FOR THE THIRD BOUNDARY-VALUE PROBLEM OF NON-STATIONARY HEAT CONDUCTIVITY WITH A CONTINUOUS SPECTRUM OF EIGENVALUES
Authors: Kartashov E. M.
Published: November 2018

The mathematical theory of constructing an integral transformation and the inversion formula for it for the third boundary value problem in a domain with a continuous spectrum of eigenvalues are developed. The method is based on the operational solution of the initial problem with an initial function of general form satisfying the Dirichlet condition and a homogeneous boundary condition of the third kind. On the basis of the obtained relations, a series of analytical solutions of the third boundary value problem for a parabolic equation in various equivalent functional forms is proposed. An integral representation of the analytic solutions of the third boundary-value problem is proposed for the general form of the representation of boundary-value functions in the initial formulation of the problem. The corresponding Green's function is written out.
DEVELOPMENT OF AN INFORMATION SySTEM FOR CALCULATING PARAMETERS OF THERMOELECTRIC COOLERS
Authors: Steshenko A. К. , Dudarev A. V.
Published: November 2018

This article describes the development of information systems for modeling a number of polynomial functions based on experimental data, on the basis of which the parameters of thermoelectric coolers are calculated. The input data is entered manually or by uploading files with input data. The calculation is carried out in several stages, including different types of calculations. Some of them are done in parallel and independently of each other. At the first stage, the functions of the measured quantities are calculated by the method of least squares. On their basis the iterative calculation of the main parameters, and also the calculation of a number of additional parameters of the branches are carried out. For convenience in analyzing results, the IS visualizes them in a tabular form and in the form of graphs, giving them in priority of importance for the operator. The results can be exported by copying or automatically in an Excel file.
METHOD OF PREPARATIVE SYNTHESIS OF 8-OXO-2'-DEOXYGUANOSINE FOR LABORATORY USING
Authors: Marmiy N. V. , Esipov D. S.
Published: November 2018

A preparative method for the synthesis of 8-oxo-2'-deoxyguanosine (8-oxo-dG) giving a high yield up to 80% and suitable for laboratory use is suggested. The urgency of the development of this method is associated with the need to obtain large quantities of 8-oxo-dG for the study of biological and pharmaceutical activity. Evidence of this need was obtained in the last decades, when the mechanisms of the interface of DNA repair with intracellular signaling through 8-oxo-dG were discovered and its anti-inflammatory and protective effects were revealed. The suggested method is based on the scheme used to prepare 8-oxo-dG-containing oligonucleotides, but has a number of important modifications. The use of N,N-dimethylformamide as a solvent makes it possible to increase the yield of the nucleophilic substitution reaction and avoid expensive and complicated further purification of silver acetate. Control of the reaction kinetics allows achieving the maximum yield and purity of the product. Alkaline hydrolysis, in contrast to ammonolysis, provides complete and rapid removal of acyl groups, and reversed-phase chromatography on silanized silica gel is an effective and inexpensive method of purification. Such a purification scheme minimizes contamination of the product with residual organic solvents, which is important for biological experiments. From the economic point of view, it is advantageous because of the absence of expensive solvents and the possibility of reusing the carrier. The method makes it possible to obtain pure 8-oxo-dG in preparative amounts and exceeds both its prototype and other existing techniques in the final output. Some intermediate compounds and significant methodological features of the reaction are described.
Revolutionäre Taktik?
Authors: Staatsmonopolistischen Kapitalismus Redaktionskollektiv: Theorie des
Published: November 2018

Revolutionäre Taktik? (Anmerkungen zu den Thesen des Parteivorstandes der DKP zur Vorbereitung ihres 2. Parteitages)