scholarly journals The impact of cobalt-60 source age on biologically effective dose in high-dose functional Gamma Knife radiosurgery

2016 ◽  
Vol 125 (Supplement_1) ◽  
pp. 154-159 ◽  
Author(s):  
Benjamin H. Kann ◽  
James B. Yu ◽  
John M. Stahl ◽  
James E. Bond ◽  
Christopher Loiselle ◽  
...  
Keyword(s):  
Effective Dose ◽  
Dose Rate ◽  
Gamma Knife ◽  
Treatment Time ◽  
Gamma Knife Radiosurgery ◽  
High Dose ◽  
Biologically Effective Dose ◽  
Obsessive Compulsive ◽  
Compulsive Disorder ◽  
Dose Rates

OBJECTIVEFunctional Gamma Knife radiosurgery (GKRS) procedures have been increasingly used for treating patients with tremor, trigeminal neuralgia (TN), and refractory obsessive-compulsive disorder. Although its rates of toxicity are low, GKRS has been associated with some, if low, risks for serious sequelae, including hemiparesis and even death. Anecdotal reports have suggested that even with a standardized prescription dose, rates of functional GKRS toxicity increase after replacement of an old cobalt-60 source with a new source. Dose rate changes over the course of the useful lifespan of cobalt-60 are not routinely considered in the study of patients treated with functional GKRS, but these changes may be associated with significant variation in the biologically effective dose (BED) delivered to neural tissue.METHODSThe authors constructed a linear-quadratic model of BED in functional GKRS with a dose-protraction factor to correct for intrafraction DNA-damage repair and used standard single-fraction doses for trigeminal nerve ablation for TN (85 Gy), thalamotomy for tremor (130 Gy), and capsulotomy for obsessive-compulsive disorder (180 Gy). Dose rate and treatment time for functional GKRS involving 4-mm collimators were derived from calibrations in the authors' department and from the cobalt-60 decay rate. Biologically plausible values for the ratio for radiosensitivity to fraction size (α/β) and double-strand break (DSB) DNA repair halftimes (τ) were estimated from published experimental data. The biphasic characteristics of DSB repair in normal tissue were accounted for in deriving an effective τ1 halftime (fast repair) and τ2 halftime (slow repair). A sensitivity analysis was performed with a range of plausible parameter values.RESULTSAfter replacement of the cobalt-60 source, the functional GKRS dose rate rose from 1.48 to 2.99 Gy/min, treatment time fell, and estimated BED increased. Assuming the most biologically plausible parameters, source replacement resulted in an immediate relative BED increase of 11.7% for GKRS-based TN management with 85 Gy, 15.6% for thalamotomy with 130 Gy, and 18.6% for capsulotomy with 180 Gy. Over the course of the 63-month lifespan of the cobalt-60 source, BED decreased annually by 2.2% for TN management, 3.0% for thalamotomy, and 3.5% for capsulotomy.CONCLUSIONSUse of a new cobalt-60 source after replacement of an old source substantially increases the predicted BED for functional GKRS treatments for the same physical dose prescription. Source age, dose rate, and treatment time should be considered in the study of outcomes after high-dose functional GKRS treatments. Animal and clinical studies are needed to determine how this potential change in BED contributes to GKRS toxicity and whether technical adjustments should be made to reduce dose rates or prescription doses with newer cobalt-60 sources.

scholarly journals Biologically effective dose and prediction of obliteration of unruptured arteriovenous malformations treated by upfront Gamma Knife radiosurgery: a series of 149 consecutive cases

2020 ◽  
pp. 1-11 ◽  
Author(s):  
Constantin Tuleasca ◽  
Iulia Peciu-Florianu ◽  
Henri-Arthur Leroy ◽  
Maximilien Vermandel ◽  
Mohamed Faouzi ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Dose Rate ◽  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Gamma Knife Radiosurgery ◽  
Biologically Effective Dose ◽  
Radiation Dose Rate ◽  
The Mean

OBJECTIVEArteriovenous malformations (AVMs) present no pathologic tissue, and radiation dose is confined in a clear targeted volume. The authors retrospectively evaluated the role of the biologically effective dose (BED) after Gamma Knife radiosurgery (GKRS) for brain AVMs.METHODSA total of 149 consecutive cases of unruptured AVMs treated by upfront GKRS in Lille University Hospital, France, were included. The mean length of follow-up was 52.9 months (median 48, range 12–154 months). The primary outcome was obliteration, and the secondary outcome was complication appearance. The marginal dose was 24 Gy in a vast majority of cases (n = 115, 77.2%; range 18–25 Gy). The mean BED was 220.1 Gy2.47 (median 229.9, range 106.7–246.8 Gy2.47). The mean beam-on time was 32.3 minutes (median 30.8, range 9–138.7 minutes). In the present series, the mean radiation dose rate was 2.259 Gy/min (median 2.176, range 1.313–3.665 Gy/min). The Virginia score was 0 in 29 (19.5%), 1 in 61 (40.9%), 2 in 41 (27.5%), 3 in 18 (12.1%), and 4 in 0 (0%) patients, respectively. The mean Pollock-Flickinger score was 1.11 (median 1.52, range 0.4–2.9). Univariate (for obliteration and complication appearance) and multivariate (for obliteration only) analyses were performed.RESULTSA total of 104 AVMs (69.8%) were obliterated at the last follow-up. The strongest predictor for obliteration was BED (p = 0.03). A radiosurgical obliteration score is proposed, derived from a fitted multivariable model: (0.018 × BED) + (1.58 × V12) + (−0.013689 × beam-on time) + (0.021 × age) − 4.38. The area under the receiver operating characteristic curve was 0.7438; after internal validation using bootstrap methods, it was 0.7088. No statistically significant relationship between radiation dose rate and obliteration was found (p = 0.29). Twenty-eight (18.8%) patients developed complications after GKRS; 20 (13.4%) of these patients had transient adverse radiological effects (perilesional edema developed). Predictors for complication appearance were higher prescription isodose volume (p = 0.005) and 12-Gy isodose line volume (V12; p = 0.001), higher Pollock-Flickinger (p = 0.02) and Virginia scores (p = 0.003), and lower beam-on time (p = 0.03).CONCLUSIONSThe BED was the strongest predictor of obliteration of unruptured AVMs after upfront GKRS. A radiosurgical score comprising the BED is proposed. The V12 appears as a predictor for both efficacy and toxicity. Beam-on time was illustrated as statistically significant for both obliteration and complication appearance. The radiation dose rate did not influence obliteration in the current analysis. The exact BED threshold remains to be established by further studies.

scholarly journals Results Following Gamma Knife Radiosurgical Anterior Capsulotomies for Obsessive Compulsive Disorder

Neurosurgery ◽  
2011 ◽  
Vol 68 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Douglas. Kondziolka ◽  
John C. Flickinger ◽  
Robert. Hudak
Keyword(s):  
Obsessive Compulsive Disorder ◽  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
Internal Capsule ◽  
Severe Form ◽  
Obsessive Compulsive ◽  
Compulsive Disorder ◽  
Bilateral Lesions ◽  
Anterior Capsulotomy

Abstract BACKGROUND: Obsessive compulsive disorder (OCD), in its severe form, can cause tremendous disability for affected patients. OBJECTIVE: To evaluate the results following bilateral radiosurgical anterior capsulotomy for severe medically refractory OCD. METHODS: We performed gamma knife anterior capsulotomy (GKAC) on 3 patients with extreme, medically intractable OCD. According to our protocol, all patients were evaluated by at least 2 psychiatrists who recommended surgery. The patient had to request the procedure, and had to have severe OCD according to the Yale-Brown Obsessive Compulsive Scale (YBOCS). Patient ages were 37, 55, and 40 years, and pre-radiosurgery YBOCS scores were 34/40, 39/40, and 39/40. Bilateral lesions were created with 2 4-mm isocenters to create an oval volume in the ventral internal capsule at the putaminal midpoint. A maximum dose of 140 or 150 Gy was used. RESULTS: There was no morbidity after the procedure, and all patients returned immediately to baseline function. All patients noted significant functional improvements, and reduction in OCD behavior. Follow-up was at 55, 42, and 28 months. The first patient reduced her YBOCS score from 34 to 24. One patient with compulsive skin picking and an open wound had later healing of the chronic wound and a reduction in the YBOCS score from 39 to 8. At 28 months, the third patient is living and working independently, and her YBOCS score is 18. CONCLUSION: Within a strict protocol, gamma knife radiosurgery provided improvement of OCD behavior with no adverse effects. This technique should be evaluated further in patients with severe and disabling behavioral disorders.

scholarly journals Efficacy of Gamma Knife Radiosurgery in Refractory Obsessive-Compulsive Disorder: An Indian Experience

2022 ◽  
Author(s):  
Sanjeev Pattankar ◽  
Milind Sankhe ◽  
Kersi Chavda
Keyword(s):  
Obsessive Compulsive Disorder ◽  
Gamma Knife ◽  
Treatment Modality ◽  
Gamma Knife Radiosurgery ◽  
Obsessive Compulsive ◽  
Noninvasive Treatment ◽  
Long Term Outcome ◽  
Compulsive Disorder ◽  
Anterior Capsulotomy

Abstract Background Obsessive-compulsive disorder (OCD) is a chronic debilitating psychiatric condition with adverse impact on patient's sociooccupational health. Refractoriness to pharmacotherapy and psychotherapy is not uncommon. Gamma Knife radiosurgery (GKRS) is the comprehensively used and reviewed treatment modality in refractory OCD worldwide. In India, the past two decades of increasing GKRS availability has failed to create the necessary local awareness of its usefulness in refractory OCD. Limited native literature deepens the problem. Objective To analyze our experience with GKRS in refractory OCD, and report the safety and efficacy/long-term outcome in patients using the Yale–Brown Obsessive-Compulsive Scale (Y-BOCS). Materials and Methods A retrospective review of patients receiving GKRS for refractory OCD between 2000 and 2020 was carried out. Case files of the eligible (n = 9) patients were reviewed for clinical, radiotherapeutic, and outcome data. Additionally, patients were contacted via telephone to enquire about their experiences, and to obtain retroactive consent for GKRS in June 2021. Information obtained was collated, computed, and analyzed. Results Male-to-female sex ratio was 8:1. Mean age at the time of GKRS and mean duration of OCD prior to GKRS was 30.1 ± 9.4 and 10.2 ± 5.8 years, respectively. Mean baseline Y-BOCS score was 29.6 ± 4.7. Our first patient received cingulotomy, while the rest underwent anterior capsulotomy. Median margin dose (50% isodose) was 70 Gy. Also, 23.8 ± 7.7 was the mean Y-BOCS score at the last follow-up (median = 30 months). Overall, 44.4% patients showed full/partial response (≥25% reduction in Y-BOCS score) at the last follow-up. In anterior capsulotomy (eight patients), patients with moderate/severe OCD showed better response (4/5 responders) than those with extreme OCD (0/3 responders). Single case of cingulotomy resulted in no response (<25% reduction in Y-BOCS score). No adverse radiation effects were noted. Also, 55.6% patients gave retroactive consent telephonically. Conclusion GKRS is a safe and effective noninvasive treatment modality for refractory OCD. Ventral anterior capsule is the preferred target. Maximum radiation doses of 120 to 160 Gy are well tolerated. Extremely severe OCD cases fared poorer. Proper awareness about the availability and efficacy of GKRS in refractory OCD is required in India.

scholarly journals Higher dose rate Gamma Knife radiosurgery may provide earlier and longer-lasting pain relief for patients with trigeminal neuralgia

2015 ◽  
Vol 123 (4) ◽  
pp. 961-968 ◽  
Author(s):  
John Y. K. Lee ◽  
Sukhmeet Sandhu ◽  
Denise Miller ◽  
Timothy Solberg ◽  
Jay F. Dorsey ◽  
...  
Keyword(s):  
Multivariate Analysis ◽  
Pain Relief ◽  
Activities Of Daily Living ◽  
Pain Intensity ◽  
Dose Rate ◽  
Gamma Knife ◽  
Daily Living ◽  
Gamma Knife Radiosurgery ◽  
Dose Rates

OBJECT Gamma Knife radiosurgery (GKRS) utilizes cobalt-60 as its radiation source, and thus dose rate varies as the fixed source decays over its half-life of approximately 5.26 years. This natural decay results in increasing treatment times when delivering the same cumulative dose. It is also possible, however, that the biological effective dose may change based on this dose rate even if the total dose is kept constant. Because patients are generally treated in a uniform manner, radiosurgery for trigeminal neuralgia (TN) represents a clinical model whereby biological efficacy can be tested. The authors hypothesized that higher dose rates would result in earlier and more complete pain relief but only if measured with a sensitive pain assessment tool. METHODS One hundred thirty-three patients were treated with the Gamma Knife Model 4C unit at a single center by a single neurosurgeon during a single cobalt life cycle from January 2006 to May 2012. All patients were treated with 80 Gy with a single 4-mm isocenter without blocking. Using an output factor of 0.87, dose rates ranged from 1.28 to 2.95 Gy/min. The Brief Pain Inventory (BPI)-Facial was administered before the procedure and at the first follow-up office visit 1 month from the procedure (mean 1.3 months). Phone calls were made to evaluate patients after their procedures as part of a retrospective study. Univariate and multivariate linear regression was performed on several independent variables, including sex, age in deciles, diagnosis, follow-up duration, prior surgery, and dose rate. RESULTS In the short-term analysis (mean 1.3 months), patients’ self-reported pain intensity at its worst was significantly correlated with dose rate on multivariate analysis (p = 0.028). Similarly, patients’ self-reported interference with activities of daily living was closely correlated with dose rate on multivariate analysis (p = 0.067). A 1 Gy/min decrease in dose rate resulted in a 17% decrease in pain intensity at its worst and a 22% decrease in pain interference with activities of daily living. In longer-term follow-up (mean 1.9 years), GKRS with higher dose rates (> 2.0 Gy/min; p = 0.007) and older age in deciles (p = 0.012) were associated with a lower likelihood of recurrence of pain. DISCUSSION Prior studies investigating the role of dose rate in Gamma Knife radiosurgical ablation for TN have not used validated outcome tools to measure pain preoperatively. Consequently, differences in pain outcomes have been difficult to measure. By administering pain scales both preoperatively as well as postoperatively, the authors have identified statistically significant differences in pain intensity and pain interference with activities of daily living when comparing higher versus lower dose rates. Radiosurgery with a higher dose rate results in more pain relief at the early follow-up evaluation, and it may result in a lower recurrence rate at later follow-up.

scholarly journals Results of Gamma Knife anterior capsulotomy for refractory obsessive-compulsive disorder: results in a series of 10 consecutive patients

2019 ◽  
Vol 131 (2) ◽  
pp. 376-383 ◽  
Author(s):  
Giorgio Spatola ◽  
Roberto Martinez-Alvarez ◽  
Nuria Martínez-Moreno ◽  
German Rey ◽  
Juan Linera ◽  
...  
Keyword(s):  
Obsessive Compulsive Disorder ◽  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
Global Changes ◽  
Maximal Dose ◽  
Obsessive Compulsive ◽  
Partial Responder ◽  
Compulsive Disorder ◽  
Anterior Capsulotomy

OBJECTIVEObsessive-compulsive disorder (OCD) is a severe psychiatric condition. The authors present their experience with Gamma Knife radiosurgery (GKRS) in the treatment of patients with OCD resistant to any medical therapy.METHODSPatients with severe OCD resistant to all pharmacological and psychiatric treatments who were treated with anterior GKRS capsulotomy were retrospectively reviewed. These patients were submitted to a physical, neurological, and neuropsychological examination together with structural and functional MRI before and after GKRS treatment. Strict study inclusion criteria were applied. Radiosurgical capsulotomy was performed using two 4-mm isocenters targeted at the midputaminal point of the anterior limb of the capsule. A maximal dose of 120 Gy was prescribed for each side. Clinical global changes were assessed using the Clinical Global Impression (CGI) scale, Global Assessment of Functioning (GAF) scale, EQ-5D, Beck Depression Inventory (BDI), and State-Trait Anxiety Inventory (STAI). OCD symptoms were determined by the Yale–Brown Obsessive Compulsive Scale (Y-BOCS).RESULTSTen patients with medically refractory OCD (5 women and 5 men) treated between 2006 and 2015 were included in this study. Median age at diagnosis was 22 years, median duration of illness at the time of radiosurgery was 14.5 years, and median age at treatment was 38.8 years. Before GKRS, the median Y-BOCS score was 34.5 with a median obsession score of 18 and compulsion score of 17. Seven (70%) of 10 patients achieved a full response at their last follow-up, 2 patients were nonresponders, and 1 patient was a partial responder. Evaluation of the Y-BOCS, BDI, STAI-Trait, STAI-State, GAF, and EQ-5D showed statistically significant improvement at the last follow-up after GKRS. Neurological examinations were normal in all patients at each visit. At last follow-up, none of the patients had experienced any significant adverse neuropsychological effects or personality changes.CONCLUSIONSGKRS anterior capsulotomy is effective and well tolerated with a maximal dose of 120 Gy. It reduces both obsessions and compulsions, improves quality of life, and diminishes depression and anxiety.

Gamma knife radiosurgery in patients with advanced breast cancer undergoing bone marrow transplant

2002 ◽  
Vol 97 ◽  
pp. 663-665 ◽  
Author(s):  
Kenneth J. Levin ◽  
Emad F. Youssef ◽  
Andrew E. Sloan ◽  
Rajiv Patel ◽  
Rana K. Zabad ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Advanced Breast Cancer ◽  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
High Dose Chemotherapy ◽  
Advanced Breast ◽  
High Dose ◽  
Initial Management ◽  
Content Type ◽  
Fine Print

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.

Sign in / Sign up

Export Citation Format

Share Document