bluuebunny/crossref_metadata_2025 huggingface dataset:
CHILDHOOD AS THE SOURCE OF A WRITER’S INSPIRATION. IGOR KLEKH
Authors: Hofmann T.
Published: November 2018

The article examines the role of autobiographical retrospections and reminiscences in Igor Klekh’s stories Diglossia [Diglossiya], A Partial Man, or Notes of a 40-year-old [Chastichniy chelovek, ili Zapiski sorokaletnego], The Judgement Day [Svetoprestavlenie], and The 1999 Chronicles [Khroniki 1999 goda]. The writer’s Soviet childhood represents an artistic technique, a unique way to perceive and organize the narration. It is possible to say that it is from a child’s perception of the world that Klekh draws his literary inspiration, and that it is nostalgia that determines his stylistic experimentation. Speaking of Klekh’s leitmotifs and poetic imagery, such as the material metaphor of memory, documentary letter, reshuffled reminiscences, etc., the author points out that it is this specifically perceived and artistically digested phenomenon of the Soviet childhood that defines Klekh’s fragmented narrative style.
Contradictory Discourses of Protection and Control in Transnational Asylum Law
Authors: Bohmer Carol , Shuman Amy
Published: November 2018

For immigration authorities, the goal of asylum hearings is to differentiate
between economic migrants and legitimate political asylum seekers. However,
in the stories asylum seekers tell, these categories often blur. Nevertheless, the
asylum process uses this differentiation to conceal inequities in the system, and
to justify denials. This article examines political asylum as a transnational and
culturally local process and argues that contradictions between protection and
control underlie some of the seemingly absurd denials of asylum applications.
Maddening Legalities
Authors: Linstroth J.P.
Published: November 2018

Donahue, Katherine C. (2007) Slave of Allah: Zacarias Moussaoui vs. The USA. Ann Arbor, MI and London: Pluto Press. (206 pp., notes, bibliography, index; price: hardcover £50.00; paperback £15.19)

Kelly, Tobias (2006) Law, Violence and Sovereignty among West Bank Palestinians. Cambridge: Cambridge University Press. (194 pp., references, index, illustrations; price: hardcover £52.25; paperback £18.99)
Women’s Rights and Sovereignty/Autonomy
Authors: Speed Shannon , Sierra María Teresa , Stephen Lynn , Johnson Jessica , Schaumberg Heike
Published: November 2018

In recent years in both the United States and Latin America,
indigenous peoples have taken increasing control over local justice,
creating indigenous courts and asserting more autonomy in the
administration of justice in their tribes, regions, or communities.
New justice spaces, such as the Chickasaw District Courts in
Oklahoma and the Zapatista Good Governance Councils in
Chiapas, work to resolve conflict based largely on indigenous
‘customs and traditions.’ Many of the cases brought before these
local legal bodies are domestic cases that directly involve issues of
gender, women’s rights and culture. Yet the relationship between
‘indigenous traditions’ and women’s rights has been a fraught one.
This forum article considers how these courts emerged in the context
of neoliberalism and whether they provide new venues for
indigenous women to pursue their rights and to challenge gendered
social norms or practices that they find oppressive.
Reflections on Cosmopolitan Politesse with Perspectives from Papua New Guinea
Authors: Hirsch Eric
Published: November 2018

In this issue’s forum, Nigel Rapport takes his lead from Georg Simmel, who asked how society is possible. Simmel notes that every individual has a sense of being connected to others, and it is through these connections that the individual has a ‘grasp of the whole complex as society’ (1971: 8). But this understanding is only realised through particular, concrete interactions. The individual in Simmel’s sociology, then, can only exist as an individual through this engagement with others – with, in short, ‘society’. It is this set of relations, it seems, that makes society possible. However, Simmel suggests that the picture an individual gains of the Other through personal contact is based on certain distortions – classifications of a general and conventional nature, some of which may be alienating. At the same time, Simmel also indicates that the individual simultaneously remains separate from society: ‘It seems, however, that every individual has in himself a core of individuality which cannot be re-created by anybody else whose core differs qualitatively from his own. . . . We cannot know completely the individuality of another’ (9–10).
Love is Love
Authors: Kerrigan Dylan
Published: November 2018

Trinidad and Tobago’s anti-gay laws can be traced back to British colonialism and European imperialism. Their existence today and their consequences for human lives in Trinidad and Tobago during the past one hundred years are a local entanglement of historic global hierarchies of power. On 12 April 2018, in the High Court of Port of Spain, capital of Trinidad and Tobago, Justice Devindra Rampersad, in a form of judicial activism, trod where local politicians have not dared and intervened in such coloniality by delivering a legal judgement upholding the challenge by Jason Jones to the nineteenth-century colonial laws in Trinidad and Tobago that criminalise homosexual relations and same-sex loving.
Leksell GammaPlan version 10.0 preview: performance of the new inverse treatment planning algorithm applied to Gamma Knife surgery for pituitary adenoma
Authors: Schlesinger David J. , Sayer Faisal T. , Yen Chun-Po , Sheehan Jason P.
Published: November 2018

Object

Treatment planning for Gamma Knife surgery has traditionally been a forward planning (FP)–only approach with results that depend significantly on the experience of the user. Leksell GammaPlan version 10.0, currently in beta testing, introduces a new inverse planning (IP) engine that may allow more reproducible results across dosimetrists and individual institutions. In this study the authors compared the FP and IP approaches to Gamma Knife surgery.

Methods

Forty-three patients with pituitary adenomas were evaluated after dose planning was performed using FP and IP treatment approaches. Treatment plans were compared for target coverage, target selectivity, Paddick gradient index, number of isocenters, optic pathways dose, and treatment time. Differences between the forward and inverse treatment plans were evaluated in a statistical fashion.

Results

The IP software generated a dose plan within approximately 10 minutes. The FP approach delivered the prescribed isodose to a larger treatment volume than the IP system (p < 0.001). The mean (± SD) FP and IP coverage indices were 0.85 ± 0.23 and 0.85 ± 0.13, respectively (no significant difference). The mean FP and IP gradient indices were 2.78 ± 0.20 and 3.08 ± 0.37, respectively (p < 0.001). The number of isocenters did not appreciably differ between approaches. The maximum doses directed to the optic apparatus for the FP and IP methods were 8.67 ± 1.97 Gy and 12.33 ± 5.86 Gy, respectively (p < 0.001).

Conclusions

The Leksell GammaPlan IP system was easy to operate and provided a reasonable, first approximation dose plan. Particularly in cases in which there are eloquent structures at risk, experience and user-based optimization will be required to achieve an acceptable Gamma Knife dose plan.
Neurological complications and symptom resolution following Gamma Knife surgery for brain metastases 2 cm or smaller in relation to eloquent cortices
Authors: Elliott Robert E. , Rush Stephen , Morsi Amr , Mehta Nisha , Spriet Jeri , Narayana Ashwatha , Donahue Bernadine , Parker Erik C. , Golfinos John G.
Published: November 2018

Object

Reports on resection of tumors in or near eloquent cortices have noted neurological complications in up to 30% of patients. This paper contains an analysis of symptom resolution and neurological morbidity following 20-Gy Gamma Knife surgery (GKS) for supratentorial brain metastases ≤ 2 cm in greatest diameter.

Methods

The authors performed a retrospective analysis of 98 consecutively treated adults (33 men and 65 women with a median age of 61.4 years at the time of GKS) with Karnofsky Performance Scale score ≥ 60, who underwent GKS for supratentorial brain metastases ≤ 2 cm in diameter. Lesion location was classified as noneloquent (Grade I), near eloquent (Grade II), or eloquent (Grade III), in accordance with the grading system developed by the group at M. D. Anderson Cancer Center. Following treatment, the patients underwent MR imaging and clinical examinations at 6 weeks and every 3 months thereafter.

Results

Ninety-eight patients underwent 20-Gy GKS for 131 metastases at initial presentation and 31 patients underwent salvage 20-Gy GKS for 76 new lesions, for a total of 207 lesions (mean lesion volume 0.44 cm3). Lesions were classified as follows: Grade I, 96 (46.4%); Grade II, 51 (24.6%); and Grade III, 60 (29%). Fifteen patients (2 with Grade II and 13 with Grade III lesions) presented with deficits referable to their lesions, yielding pre-GKS deficit rates of 7.2% per lesion and 15.3% per patient. The pre-GKS deficits improved or resolved in 10 patients (66.7%) at a median time of 2.8 months and remained stable in 3 patients (20%). Two patients (13.3%) experienced worsened neurological deficits. One patient who was neurologically intact prior to treatment developed a new hemiparesis (1 of 83 patients [1.2%]). The rates of permanent neurological deterioration following GKS for Grades I, II, and III lesions were 0% (0 of 96 tumors), 2% (1 of 51), and 3.3% (2 of 60), respectively. The pre-GKS neurological deficits and larger lesions were the most significant risk factors for post-GKS neurological deterioration.

Conclusions

Gamma Knife surgery performed using a 20-Gy dose provides amelioration of neurological deficits from brain metastases that are ≤ 2 cm in diameter and located in or near eloquent cortices in nearly two-thirds of patients with a low incidence of morbidity. Consistent with the surgical literature, higher rates of neurological complications were observed as proximity to eloquent regions and lesion size increased. There was no neurological deterioration in patients harboring metastases in noneloquent areas.
Apparent diffusion coefficients for evaluation of the response of brain tumors treated by Gamma Knife surgery
Authors: Huang Chuan-Fu , Chiou Shyh-Ying , Wu Ming-Fang , Tu Hsien-Tang , Liu Wen-Shan , Chuang Jim-Chao
Published: November 2018

Object

Cellular density is a major factor for change in the apparent diffusion coefficient (ADC). The authors hypothesized that loss of tumor cells after Gamma Knife surgery (GKS) may alter the ADC value and used diffusion weighted MR imaging (DW imaging) to evaluate cellular changes in brain tumors to detect their treatment response and the efficacy of GKS.

Methods

In this paper the authors describe a prospective trial involving 86 patients harboring 38 solid or predominantly solid brain metastases, 30 meningiomas, and 24 acoustic neuromas that were treated by GKS. The patients underwent serial MR imaging examinations, including DW imaging, before treatment and at multiple intervals following GKS. Follow-up MR images and clinical outcomes were reviewed at 3-month intervals for metastatic lesions and at 6-month intervals for benign tumors. Apparent diffusion coefficients were calculated from echoplanar DW images, and mean ADC values were compared at each follow-up.

Results

The mean ADC value for all meningiomas was 0.82 ± 0.15 × 10−3 mm2/sec before GKS. The mean ADC value as of the last mean follow-up of 42 months was 1.36 ± 0.19 × 10−3 mm2/sec, a significant increase compared to that before treatment (p < 0.0001). Calcification (p = 0.006) and tumor recurrence (p = 0.025) significantly prevented a rise in the ADC level.

The mean ADC value for all solid acoustic neuromas was 1.06 ± 0.17 × 10−3 mm2/sec before GKS. The mean ADC value as of the last mean follow-up of 36 months was 1.72 ± 0.26 × 10−3 mm2/sec, a significant increase (p = 0.0002) compared with values before GKS. At the last mean MR imaging follow-up there appeared to be tumor enlargement in 3 patients (12.5%); however, since the ADC values in these patients were significantly higher than the preradiosurgery values, the finding was considered to be a sign of radiation necrosis rather than tumor recurrence.

The mean ADC value of metastatic tumors was 1.05 ± 0.12 × 10−3 mm2/sec before GKS. This value rose significantly (p < 0.0001) to 1.64 ± 0.18 × 10−3 mm2/sec after GKS at a mean follow-up of 9.4 months. Magnetic resonance imaging showed that 89% of these tumors had been controlled by GKS. In 2 patients there were enlarged lesions, but the ADC values were the same as pre-GKS levels, and therefore, the lesions were deemed recurrent.

Conclusions

Apparent diffusion coefficient values may be useful in evaluating treatment results before a definitive change in volume is evident on imaging studies. In some patients in whom imaging findings are equivocal, ADC values may also be used to distinguish radiation-induced necrosis from tumor recurrence.
Gamma Knife surgery for optic glioma
Authors: Liang Cheng-Loong , Lu Kang , Liliang Po-Chou , Chen Han-Jung
Published: November 2018

Optic pathway/hypothalamic gliomas represent approximately 2%–5% of brain tumors in children. Total excision, subtotal excision, subtotal excision followed by irradiation, radiation therapy alone, chemotherapy, and no treatment at all have been reported. In this article the authors discuss the results of Gamma Knife surgery (GKS) for optic gliomas in 2 children.

Two pediatric patients, a boy and a girl, underwent GKS for optic gliomas at our hospital between March 2005 and August 2005. The children's ages were 10 and 16 years at presentation. The histological diagnosis was confirmed to be pilocytic astrocytoma in both cases. The tumor involved the optic chiasm in 1 patient and the right optic nerve in the other patient. Treatments were planned with the prescription of 11 Gy to the 50% isodose line for the optic chiasm glioma and 15 Gy to the 50% isodose line for the optic nerve glioma.

In both patients, GKS was well tolerated. The follow-up periods were 60 and 55 months. Complete response with near-total disappearance of the tumors was observed in both patients. During the follow-up period, neither of the patients developed any endocrine dysfunction.

Gamma Knife surgery permits treatment of optic glioma with good tumor control and no clinically relevant morbidity. With the ability to deliver a high dose to the tumor while sparing normal brain tissue, especially the optic nerve, optic chiasm, and pituitary gland, GKS should be the choice of treatment for optic gliomas. A larger number of patients and long-term follow-up are required for further evaluation of the efficacy and potential side effects of GKS.
In vitro biological dosimeter modeling of the glioblastoma response to radiation delivered by the Gamma Knife
Authors: Smith Ryan , Smith Kris A. , Biggs Christopher A. , Scheck Adrienne C.
Published: November 2018

Object

The goal of this study was to develop an assay that makes possible the assessment of the glioma cell response to single-fraction high-dose Gamma Knife surgery. In this assay, the isolation of radioresistant cell subpopulations facilitates mechanistic studies of radioresistance.

Methods

A tissue-equivalent paraffin phantom with an aperture capable of holding an Opticell cell culture cassette was developed for treatment with the Leksell Gamma Knife model C. A second apparatus, which the authors also created, uses the manufacturer-supplied polystyrene phantom, thereby allowing this assay to be performed in the Leksell Gamma Knife Perfexion. After treatment, the cells were morphologically assessed to determine their response to radiation treatment. Two specific parameters were used to determine radiosensitivity: 1) the diameter of the clearing zone, defined as the central region of cell death; and 2) the number of surviving colonies within this central high-dose clearing zone.

Results

Radioresistance was compared in 2 different cell lines from glioblastomas. The first cell line, ME, was established from a primary tumor before its treatment, and the second cell line, DIV, was established from a tumor that recurred after treatment with chemotherapy and fractionated radiotherapy. The ME cell line had the most robust response to radiosurgery, as characterized by a consistently larger clearing zone (28.33 ± 1.1 mm). In contrast, the clearing zone produced when the DIV cell line was used was 24.0 ± 1 mm, indicating an approximate response difference of 5 Gy. The mean number of surviving colonies within the clearing zone for the ME cell line was 1.33 ± 1 compared with that for the DIV cell line, which was 66.67 ± 2.

Conclusions

The authors developed a biological dosimeter to model the response of cells from glioblastomas to single-fraction high-dose radiation. This system also allows the identification and isolation of radioresistant cells.
Gamma Knife surgery for recurrent or residual trigeminal neuralgia after a failed initial procedure
Authors: Huang Chuan-Fu , Chiou Shyh-Ying , Wu Ming-Fang , Tu Hsien-Tang , Liu Wen-Shan
Published: November 2018

Object

The purpose of this study was to assess outcomes of Gamma Knife surgery (GKS) as a second treatment for recurrent or residual trigeminal neuralgia (TN) after failure of 3 initial procedures: microvascular decompression (MVD), GKS, and percutaneous radiofrequency rhizotomy (PRR).

Methods

Between 1999 and 2008, 65 patients (31 men [48%] and 34 women [52%]) with recurrent TN were treated with GKS. All 65 patients had undergone previous medical procedures that failed to achieve sufficient pain relief: 27 patients (42%) had undergone MVD, 8 (12%) had undergone PRR, and 30 (46%) had undergone GKS as the initial treatment. The entry zone of the trigeminal nerve was targeted using a 4-mm collimator and treated with 35–90 Gy. The isocenter was positioned so that the brainstem surface was usually irradiated at an isodose no greater than 20% (59 patients) to 30% (6 patients). The median duration of TN symptoms in these patients was 39 months (range 1–192 months).

Results

At the clinical evaluation, 42 patients (65%) with idiopathic TN reported successful pain control at a median follow-up point of 64 months (range 18–132 months). Of these patients, 33 (51%) were no longer using medication. At the 1-, 2-, and 3-year follow-up examinations, 74%, 71%, and 66% of patients experienced successful pain control, respectively. There was no significant difference in pain relief in the initial MVD group compared with the initial GKS and initial PRR groups (74% vs 59% and 50%, respectively; p = 0.342). Recurrence of pain was noted in 23 patients. Twelve of these 23 patients underwent another GKS, resulting in pain control in 8 patients (67%); 8 other patients underwent MVD, resulting in pain relief in 7 patients (87.5%). The median time from GKS to pain recurrence was 7 months (range 3–48 months). There was no significant difference in new facial numbness among the 3 groups (p = 0.24); however, in the initial GKS group, facial numbness was significantly associated with freedom from pain (p = 0.0012). There was a significant correlation between the total radiation dose and facial numbness. The cutoff value for facial numbness ranged from 115 to 120 Gy (p = 0.037).

Conclusions

Gamma Knife surgery as a second treatment achieved acceptable levels of pain control in 65% of patients with residual or recurrent TN after long-term follow-up. Initial treatment was not a factor that affected pain control, but salvage surgery may be considered separately for each group.
Use of apparent diffusion coefficients in evaluating the response of vestibular schwannomas to Gamma Knife surgery
Authors: Chuang Chun-Chao , Chang Cheng-Siu , Tyan Yu-Sheng , Chuang Keh-Shih , Tu Hsien-Tang , Huang Chuan-Fu
Published: November 2018

Object

Cellular density is a major factor responsible for changes in apparent diffusion coefficients (ADCs). The authors hypothesized that loss of tumor cells after Gamma Knife surgery (GKS) might alter ADC values. Magnetic resonance imaging, including diffusion-weighted (DW) imaging, was performed to detect cellular changes in brain tumors so that the authors could evaluate the tumor response to GKS as well as the efficacy of the procedure.

Methods

The authors conducted a prospective trial involving 31 patients harboring solid or cystic vestibular schwannomas (VSs) that were treated with GKS. The patients underwent serial MR imaging, including DW imaging, before GKS and at multiple intervals following the procedure. The authors observed the patients over time, evaluating MR imaging findings and clinical outcomes at 6-month intervals. The ADCs were calculated from echo-planar DW images, and mean ADC values were compared at each follow-up.

Results

The mean follow-up period was 36.5 months (range 18–60 months). Imaging studies showed a reduction in tumor volume in 19 patients (61.3%) and tumor growth arrest in 9 patients (29%). In the remaining 3 patients (9.7%), tumor enlargement was documented at 18, 36, and 42 months.

The mean ADC value before GKS for all solid VSs was 1.06 ± 0.17 × 10−3 mm2/second, which significantly increased 6 months after GKS and continued to increase with time (p = 0.0086). The mean ADC value for treated solid tumors as of the last mean follow-up of 36 months (range 18–60 months) was 1.72 ± 0.26 × 10−3 mm2/second (range 1.50–2.09 × 10−3 mm2/second), which was significantly higher than that before GKS (p = 0.0001). Tumor volumes were positively related to ADC values (p = 0.03).

The mean ADC value before GKS for all cystic VSs was 2.09 ± 0.24 × 10−3 mm2/second (range 1.80–2.58 × 10−3 mm2/second). The mean ADC value for treated cystic tumors as of the last mean follow-up of 38 months (range 18–48 months) was 1.89 ± 0.22 × 10−3 mm2/second.

In 3 patients harboring solid VSs, the tumor enlarged after GKS but the ADC values were higher than those before GKS. The authors considered these tumors to be controlled and continued follow-up in the patients.

Conclusions

Apparent diffusion coefficient values may be useful for evaluating treatment results before any definite volume change is detected on imaging studies and for distinguishing radiation-induced necrosis from tumor recurrence in cases in which other imaging results are not definitive, as in cases of increased tumor volume or no volume change. The authors suggest that ADC measurements be included during routine MR imaging examinations for the evaluation of GKS results.
Outcome after Gamma Knife surgery for intracranial arteriovenous malformations in children
Authors: Tamura Noriko , Hayashi Motohiro , Chernov Mikhail , Tamura Manabu , Horiba Ayako , Konishi Yoshiyuki , Muragaki Yoshihiro , Iseki Hiroshi , Okada Yoshikazu
Published: November 2018

Object

The focus of the present study was the evaluation of outcomes after unstaged and staged-volume Gamma Knife surgery (GKS) in children harboring intracranial arteriovenous malformations (AVMs).

Methods

Twenty-two children (median age 9.5 years) underwent GKS for AVMs and were followed up for at least 2 years thereafter. The disease manifested with intracranial hemorrhage in 77% of cases. In 68% of patients the lesion affected eloquent brain structures. The volume of the nidus ranged from 0.1 to 6.7 cm3. Gamma Knife surgery was guided mainly by data from dynamic contrast-enhanced CT scans, with preferential targeting of the junction between the nidus and draining vein. The total prescribed isodose volume was kept below 4.0 cm3, and the median margin dose was 22 Gy (range 20–25 Gy). If the volume of the nidus was larger than 4.0 cm3, a second radiosurgical session was planned for 3–4 years after the first one. Nine patients in the present series underwent unstaged radiosurgery, whereas staged-volume treatment was scheduled in 13 patients.

Results

Complete obliteration of the AVM was noted in 17 (77%) of 22 patients within a median period of 47 months after the last radiosurgical session. Complete obliteration of the lesion occurred in 89% of patients after unstaged treatment and in 62.5% after staged GKS. Four (67%) of 6 high-grade AVMs were completely obliterated. Complications included 3 bleeding episodes, the appearance of a region of hyperintensity on T2-weighted MR images in 2 patients who had no symptoms, and reappearance of the nidus in the vicinity of the completely obliterated AVM in 1 patient.

Conclusions

Radiosurgery is a highly effective management option for intracranial AVMs in children. For larger lesions, staged GKS may be applied successfully. Initial targeting of the nidus adjacent to the draining vein and application of a sufficient radiation dose to a relatively small volume (≤ 4 cm3) provides a good balance between a high probability of obliteration and a low risk of treatment-related complications.
Gamma Knife surgery for hemifacial spasm related to cerebellopontine angle tumors
Authors: Chang Cheng-Siu , Chuang Chun-Chao , Wu Ming-Fan , Liu Wen-Shan , Tu Hsien-Tang , Huang Chuan-Fu
Published: November 2018

Object

Most cases of tumor-related hemifacial spasm (HFS) are treated by open surgery. The authors report the effects of Gamma Knife surgery (GKS) on benign tumor–related HFS at a mean follow-up time of 84 months.

Methods

Between 2000 and 2011, 6 patients (5 women and 1 man) harboring single tumors of the cerebellopontine angle (4 meningiomas and 2 vestibular schwannomas [VSs]) and experiencing HFS underwent GKS as a primary treatment. The mean age of the patients at the time of radiosurgery was 52.7 years (range 45–60 years).

The patients' tumors lay within the radiosurgical target area. In the 4 cases of meningioma, the mean radiosurgical treatment volume was 5.3 cm3 (range 1.2–9.6 cm3), and the mean radiosurgical tumor margin dose was 14.1 Gy (range 12–18 Gy); in the 2 cases of VS, the treatment volume was 2.5 cm3 in 1 patient and 11.2 cm3 in the other, and the margin doses were 11.5 and 12 Gy, respectively. The mean duration of HFS symptoms was 15.5 months (range 3–36 months).

Results

The mean follow-up period was 84 months (range 40–110 months). Overall, 4 (66%) of the 6 patients experienced complete relief from HFS without medication after GKS and 1 patient obtained a good outcome. The mean time for improvement to be realized was 12.6 months (range 3–24 months). Only 1 patient failed to experience relief from HFS, and coincidentally, the tumor did not shrink in that case. In all 6 patients (100%), tumor growth was controlled at a mean follow-up of 56 months after GKS: in 5 patients the tumor had decreased in size and in the other patient the tumor size remained unchanged. No new neurological deficit was noted after GKS, and 1 patient with facial numbness reported improvement after tumor shrinkage.

Conclusions

Gamma Knife surgery appears to be effective in treating benign tumor–related HFS and in controlling tumor growth. A reduction in tumor volume is related to spasm improvement. Although a time latency for spasm relief is associated with GKS, minimal side effects are expected.
Radiosurgery for benign tumors of the spine using the Synergy S with cone-beam computed tomography image guidance
Authors: Gerszten Peter C. , Chen Stephanie , Quader Mubina , Xu Yuanguang , Novotny Josef , Flickinger John C.
Published: November 2018

Object

There is a growing body of evidence to support the safe and effective use of spine radiosurgery. However, there is much less experience regarding the use of radiosurgery for the treatment of benign as opposed to malignant spine tumors. This study represents an evaluation of, and reporting on, the technical aspects of using a dedicated radiosurgery system for the treatment of benign spine tumors.

Methods

Forty-five consecutive benign spine tumors were treated using the Elekta Synergy S 6-MV linear accelerator with a beam modulator and cone-beam computed tomography (CBCT) image guidance technology for target localization. The study cohort included 16 men and 29 women, ranging in age from 23 to 88 years (mean age 52 years). There were 14 cervical, 12 thoracic, 14 lumbar, and 5 sacral tumors. Forty-one lesions (91%) were intradural. The most common histological types of tumor were schwannoma, neurofibroma, and meningioma. Indications for radiosurgery included primary treatment in 24 cases (53%) and treatment of recurrent or residual tumor after open resection in 21 cases (47%).

Results

No subacute or long-term spinal cord or cauda equina toxicity occurred during the follow-up period (median 32 months). The mean maximum dose received by the gross tumor volume (GTV) was 16 Gy (range 12–24 Gy) delivered in a single fraction in 39 cases. The mean lowest dose received to the GTV was 12 Gy (range 8–16 Gy). The GTV ranged from 0.37 to 94.5 cm3 (mean 13.7 cm3, median 5.9 cm3). In the majority of cases, a planning target volume expansion of 2 mm was employed (38 cases; 84%). The mean maximum point dose delivered to the spinal cord was 8.7 Gy (range 4–11.5 Gy); the mean volume of the spinal cord that received greater than 8 Gy was 0.9 cm3 (range 0.0–5.1 cm3); and the mean dose delivered to 0.1 cm3 of the spinal cord was 7.5 Gy (range 3–10.5 Gy). The mean maximum point dose delivered to the cauda equina was 10 Gy (range 0–13 Gy); the mean volume of the cauda equina that received greater than 8 Gy was 1.45 cm3 (range 0.0–10.6 cm3); and the mean dose delivered to 0.1 cm3 of the cauda equina was 8 Gy (range 0.5–11 Gy).

Conclusions

In this study the authors describe the contouring and prescribed dose techniques used in the treatment planning and delivery of radiosurgery for benign neoplasms of the spine using CBCT image guidance. This technique may serve as an important reference for the performance of radiosurgery when one believes it is clinically indicated as a treatment modality for a benign spine tumor that is associated with both a high safety profile and a strong positive clinical outcome.
Biological implications of whole-brain radiotherapy versus stereotactic radiosurgery of multiple brain metastases
Authors: Xue Jinyu , Kubicek Gregory J. , Grimm Jimm , LaCouture Tamara , Chen Yan , Goldman H. Warren , Yorke Ellen
Published: November 2018

Object

The efficacy and safety of treatment with whole-brain radiotherapy (WBRT) or with stereotactic radiosurgery (SRS) for multiple brain metastases (> 10) are topics of ongoing debate. This study presents detailed dosimetric and biological information to investigate the possible clinical outcomes of these 2 modalities.

Methods

Five patients with multiple brain metastases (n = 11–23) underwent SRS. Whole-brain radiotherapy plans were retrospectively designed with the same MR image set and the same structure set for each patient, using the standard opposing lateral beams and fractionation (3 Gy × 10).

Physical radiation doses and biologically effective doses (BEDs) in WBRT and SRS were calculated for each lesion target and for the normal brain tissues for comparison of the 2 modalities in the context of clinical efficacy and published toxicities.

Results

The BEDs targeted to the tumor were higher in SRS than in WBRT by factors ranging from 2.4- to 3.0- fold for the mean dose and from 3.2- to 5.3-fold for the maximum dose. In the 5 patients, mean BEDs in SRS (calculated as percentages of BEDs in WBRT) were 1.3%–34.3% for normal brain tissue, 0.7%–31.6% for the brainstem, 0.5%–5.7% for the chiasm, 0.2%–5.7% for optic nerves, and 0.6%–18.1% for the hippocampus.

Conclusions

The dose-volume metrics presented in this study were essential to understanding the safety and efficacy of WBRT and SRS for multiple brain metastases. Whole-brain radiotherapy results in a higher incidence of radiation-related toxicities than SRS. Even in patients with > 10 brain metastases, the normal CNS tissues receive significantly lower doses in SRS. The mean normal brain dose in SRS correlated with the total volume of the lesions rather than with the number of lesions treated.
Quantifying and improving the efficiency of Gamma Knife treatment plans for brain metastases: results of a 1-year audit
Authors: Wright Gavin , Hatfield Paul , Loughrey Carmel , Reiner Beatrice , Bownes Peter
Published: November 2018

Object

A method for quantifying the efficiency of Gamma Knife treatment plans for metastases was previously implemented by the authors to retrospectively identify the least efficient plans and has provided insights into improved planning strategies. The aim of the current work was to ascertain whether those insights led to improved treatment plans.

Methods

Following completion of the initial study, a 1-year audit of metastasis plans created at St. James's Institute of Oncology was carried out. Audited recent plans were compared with the earlier plans of the initial study, in terms of their efficiency and dosimetric quality. The statistical significance of any differences between relevant plan parameters was quantified by Mann-Whitney U-tests. Comparisons were made between all plans and repeated for a reduced set of plans from which the smallest lesions treated with a single 4-mm shot were excluded. The plan parameters compared were a plan efficiency index (PEI), the number of shots, Paddick conformity index (PCI), gradient index (GI), and percent coverage (of the lesion by the prescription isodose).

Results

A total of 157 metastatic lesions were included in the audit and were compared with 241 in the initial study. In a comparison of all cases, the audited plans achieved a higher median PEI score than did the earlier plans from the initial study (1.08 vs 1.02), indicating improved efficiency of the audited plans. When the smallest lesions (for which there was little scope for varying plan strategy) were discounted, the improvement in median PEI score was greater (1.23 vs 1.03, p < 0.001). This improvement in efficiency corresponds to an estimated mean (maximum) time saving of 15% (66%) per lesion (11 minutes [64 minutes] on the day of treatment). The modified planning strategy yielding these efficiency improvements did not rely on the use of significantly fewer shots (median 11 vs 11 shots, p = 0.924), nor did it result in significant detriment to dosimetric quality (median coverage 99% vs 99%, median PCI 0.84 vs 0.83, p = 0.449, and median GI 2.72 vs 2.67, p = 0.701, audited plans vs initial plans, respectively).

Conclusions

Choice of planning strategy can substantially affect plan efficiency and thus strongly influence treatment time. Through increased emphasis on efficiency, resulting from the introduction of PEI combined with a modified planning strategy informed by previous work, it has been possible to reduce times for metastatic plans without compromising their dosimetric quality. Although the average time savings achieved per lesion are moderate, the potential benefits per patient are greater for those with multiple metastases. Reducing treatment times has clear benefits with regard to patient comfort and throughput. In addition, optimization of plan efficiency may potentially affect the biologically effective dose from Gamma Knife treatments and offers opportunity for further work.
Stereotactic radiosurgery for intraventricular brain metastases
Authors: Farnia Benjamin , Voong K. Ranh , Brown Paul D. , Allen Pamela K. , Guha-Thakurta Nandita , Prabhu Sujit S. , Rao Ganesh , Wang Qianghu , Zhao Zhongxiang , Mahajan Anita
Published: November 2018

Object

The authors' institution previously reported a 69% rate of crude local control for surgical management of lateral ventricle metastases at the University of Texas MD Anderson Cancer Center. For comparison, the authors here report their institutional experience with use of stereotactic radiosurgery (SRS) to treat intraventricular metastases.

Methods

To identify patients with intraventricular metastases for this retrospective review, the authors queried an institutional SRS database containing the medical records of 1962 patients with 5800 brain metastases who consecutively underwent SRS from June 2009 through October 2013. End points assessed were local control (crude and locoregional), distant failure–free survival, progression-free survival, and overall survival.

Results

Of the 1962 records examined, those for 25 (1.3%) patients with 30 (0.52%) intraventricular metastases were identified. Median patient age at SRS was 55.8 years. The most common primary malignancy was renal cell carcinoma (n = 13), followed by melanoma (n = 7) and breast adenocarcinoma (n = 5). Median tumor volume was 0.75 cm3 (range 0.01–5.6 cm3). Most lesions were located in the lateral ventricles (n = 25, 83.3%) and were treated to a median dose of 20 Gy (range 14–20 Gy). A total of 12 (48%) patients received whole-brain radiation therapy, most (n = 10) before SRS. With a median follow-up of 11.4 months (range 1.6–39.2 months), the rate of crude local control was 93.3%, and the rates of 6-month and 1-year actuarial locoregional control were 85.2% and 56.2%, respectively. The median overall survival time after SRS was 11.6 months (range 1.3–38.9 months), and the 6-month and 1-year actuarial rates were 87.1% and 46.7%, respectively. Disease dissemination developed in 7 (28%) patients as a second intraventricular metastatic lesion (n = 3, 12%), leptomeningeal disease (n = 3, 12%), or both (n = 1, 4%). Radiographic changes developed in 5 (20%) patients and included necrosis (n = 2, 8%) and hemorrhage (n = 3, 12%). A primary diagnosis of renal cell carcinoma was associated with an improved rate of distant failure–free survival (p = 0.05) and progression-free survival (p = 0.08).

Conclusions

SRS provides excellent local control for intraventricular metastases, with acceptable treatment-related toxicity, thereby supporting nonsurgical treatment for these lesions. The propensity for intraventricular dissemination among intraventricular metastases seems to be histologically dependent.
Subcutaneous granulocyte colony-stimulating factor administration for subacute traumatic spinal cord injuries, report of neurological and functional outcomes: a double-blind randomized controlled clinical trial
Authors: Derakhshanrad Nazi , Saberi Hooshang , Yekaninejad Mir Saeed , Joghataei Mohammad Taghi
Published: November 2018

OBJECTIVE

Granulocyte-colony stimulating factor (G-CSF) is a major cytokine that has already been clinically verified for chronic traumatic spinal cord injuries (TSCIs). In this study, the authors set out to determine the safety and efficacy of G-CSF administration for neurological and functional improvement in subacute, incomplete TSCI.

METHODS

This phase II/III, prospective, double-blind, placebo-controlled, parallel randomized clinical trial was performed in 60 eligible patients (30 treatment, 30 placebo). Patients with incomplete subacute TSCIs with American Spinal Injury Association Impairment Scale (AIS) grades B, C, and D were enrolled. Patients were assessed using the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) scale, Spinal Cord Independence Measure (SCIM-III) and International Association of Neurorestoratology Spinal Cord Injury Functional Rating Scale (IANR-SCIFRS), just before intervention and at 1, 3, and 6 months, after 7 daily subcutaneous administrations of 300 μg/day of G-CSF in the treatment group and placebo in the control group.

RESULTS

Among 60 participants, 28 patients (93.3%) in the G-CSF group and 26 patients (86.6%) in the placebo group completed the study protocol. After 6 months of follow-up, the AIS grade remained unchanged in the placebo group, while in the G-CSF group 5 patients (45.5%) improved from AIS grade B to C, 5 (45.5%) improved from AIS grade C to grade D, and 1 patient (16.7%) improved from AIS grade D to E. The mean ± SEM change in ISNCSCI motor score in the G-CSF group was 14.9 ± 2.6 points, which was significantly greater than in the placebo group (1.4 ± 0.34 points, p < 0.001). The mean ± SEM light-touch and pinprick sensory scores improved by 8.8 ± 1.9 and 10.7 ± 2.6 points in the G-CSF group, while those in the placebo group improved by 2.5 ± 0.60 and 1.2 ± 0.40 points, (p = 0.005 and 0.002, respectively). Evaluation of functional improvement according to the IANR-SCIFRS instrument revealed significantly more functional improvement in the G-CSF group (10.3 ± 1.3 points than in the placebo group (3.0 ± 0.81 points; p < 0.001). A significant difference was also observed between the 2 groups as measured by the SCIM-III instrument (29.6 ± 4.1 vs 10.3 ± 2.2, p < 0.001).

CONCLUSIONS

Incomplete subacute TSCI is associated with significant motor, sensory, and functional improvement after administration of G-CSF.

Clinical trial registration no.: IRCT201407177441N3 (www.irct.ir)
Effect of subpixel magnetic resonance imaging shifts on radiosurgical dosimetry for vestibular schwannoma
Authors: Borden Jonathan A. , Tsai Jen-san , Mahajan Anita
Published: November 2018

Object. The purpose of this study was to evaluate subpixel magnetic resonance (MR) imaging shifts of intracanalicular vestibular schwannomas (VSs) with respect to the internal auditory canal (IAC) as documented on computerized tomography (CT) scanning and to investigate the source of imaging-related localization errors in radiosurgery as well as the effect of such shifts on the dosimetry for small targets.

Methods. A shift of the stereotactic coordinates of intracanalicular VSs between those determined on MR imaging and those on CT scanning represents an error in localization. A shift vector places the tumor within the IAC and measures the CT scan/MR image discrepancy. The shift vectors were measured in a series of 15 largely intracanalicular VSs (all < 1.5 cm3 in volume). Using dose volume histogram measurements, the overlap between shifted and unshifted tumors and radiosurgical treatment plans were measured. Using plastic and bone phantoms and thermoluminescent dosimetry measurements, the correspondence between CT and MR imaging targets and treatments delivered using the Leksell gamma knife were measured. Combining these measurements, the correspondence between intended and actual treatments was measured.

Conclusions. The delivery of radiation to CT-imaged targets was accurate to the limits of measurement (∼ 0.1 mm). The MR imaging shifts seen in the y axis averaged 0.9 mm and in the z axis 0.8 mm. The corresponding percentage of tumor coverage with respect to apparent target shift decreased from 98 to 77%. This represents a significant potential error when targets are defined solely by MR imaging.
Morphological redifferentiation in a malignant astrocytic tumor after gamma knife radiosurgery
Authors: Szeifert György T. , Massager Nicolas , Brotchi Jacques , Levivier Marc
Published: November 2018

Object. The purpose of this study was to demonstrate positron emission tomography (PET), histological, and immunohistochemical data supporting the notion of morphological redifferentiation in a malignant astrocytic tumor after gamma knife radiosurgery (GKS).

Methods. The 11C- methionine-PET activity, Ki-67 labeling index (LI), and p53 protein expression were examined using immunohistochemical methods to assess tumor proliferative capacity. Tissue samples were obtained before and after radiosurgery in a patient with a malignant (Grade III) cerebellar astrocytoma.

Positron emission tomography scans obtained 5.5 months following radiosurgery were suggestive of decreased tumor proliferative capacity and radionecrosis. Histological examination of tumor tissue removed 42 months before GKS was characteristic of a diffuse Grade III astrocytoma in every part of the resected tumor. Similar material removed 6 months after GKS was consistent with a Grade II astrocytoma in the great majority of the resected tumor.

Conclusions. Histopathological examination showed positive phenotypic modification (redifferentiation) consistent with a Grade II astrocytoma in the majority of tumor specimens after radiosurgery. After GKS both the Ki-67 LI and p53 reaction decreased considerably as did 11C methionine uptake. Because p53 is one of the essential genes involved in the radiation response, mutations induced by the ionizing effect of gamma rays might promote partial repair of this gene's tumor suppressor function.
Hearing preservation in vestibular schwannoma stereotactic radiosurgery: what really matters?
Authors: Linskey Mark E.
Published: November 2018

Stereotactic radiosurgery (SRS) for vestibular schwannomas has evolved and improved over time. Although early short-term follow-up reports suggest that fractionation yields hearing preservation rates equivalent to modern single-dose SRS techniques, significant questions remain regarding long-term tumor control after the use of fractionation in a late responding tumor with a low proliferative index and α/β ratio. With single-dose SRS, critical hearing preservation variables include: 1) strict attention to prescription dose 3D conformality so that the ventral cochlear nucleus (VCN) receives ≤ 9 Gy; 2) careful delineation of the 3D tumor margin to exclude the cochlear nerve when visualizable with contrast-enhanced T2-weighted MR volumetric imaging techniques and exclusion the dura mater of the anterior border of the internal auditory canal; 3) a tumor margin dose prescription ≤ 12 Gy; 4) optimization of the tumor treatment gradient index without sacrificing coverage and conformality; and 5) strict attention to prescription dose 3D conformality so that the modiolus and the basal turn of the cochlea receive the lowest possible dose (ideally < 4–5.33 Gy). Testable correlates for the relative importance of the VCN versus cochlear dose given the tonotopic organization of each structure suggests that VCN toxicity should lead to preferential loss of low hearing frequencies, while cochlear toxicity should lead to preferential loss of high hearing frequencies. The potential after SRS for hearing toxicity from altered endolymph and/or perilymph fluid dynamics either via impaired fluid production and/or absorption has yet to be explored. Serous otitis media, ossicular or temporal bone osteonecrosis, and chondromalacia are not likely to be relevant factors or considerations for hearing preservation after SRS.