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Sample records for gamma knife surgery

  1. Gamma Knife Surgery in Trigeminal Neuralgia.

    PubMed

    Wolf, Amparo; Kondziolka, Douglas

    2016-07-01

    Gamma knife surgery (GKS) represents a safe, effective, and relatively durable noninvasive treatment option for patients with trigeminal neuralgia (TN) and recurrent TN. By one year's time, 75% to 90% of patients will have obtained pain relief, defined as Barrow Neurological Institute grades I to IIIB. Similar rates have been demonstrated for patients undergoing a second GKS for recurrent TN. Predictors of durability of GKS in TN include type I TN, post-GKS Barrow Neurological Institute score, and the presence of post-Gamma Knife facial numbness. PMID:27324996

  2. Repeat Gamma Knife surgery for vestibular schwannomas

    PubMed Central

    Lonneville, Sarah; Delbrouck, Carine; Renier, Cécile; Devriendt, Daniel; Massager, Nicolas

    2015-01-01

    Background: Gamma Knife (GK) surgery is a recognized treatment option for the management of small to medium-sized vestibular schwannoma (VS) associated with high-tumor control and low morbidity. When a radiosurgical treatment fails to stop tumor growth, repeat GK surgery can be proposed in selected cases. Methods: A series of 27 GK retreatments was performed in 25 patients with VS; 2 patients underwent three procedures. The median time interval between GK treatments was 45 months. The median margin dose used for the first, second, and third GK treatments was 12 Gy, 12 Gy, and 14 Gy, respectively. Six patients (4 patients for the second irradiation and 2 patients for the third irradiation) with partial tumor regrowth were treated only on the growing part of the tumor using a median margin dose of 13 Gy. The median tumor volume was 0.9, 2.3, and 0.7 cc for the first, second, and third treatments, respectively. Stereotactic positron emission tomography (PET) guidance was used for dose planning in 6 cases. Results: Mean follow-up duration was 46 months (range 24–110). At the last follow-up, 85% of schwannomas were controlled. The tumor volume decreased, remained unchanged, or increased after retreatment in 15, 8, and 4 cases, respectively. Four patients had PET during follow-up, and all showed a significant metabolic decrease of the tumor. Hearing was not preserved after retreatment in any patients. New facial or trigeminal palsy did not occur after retreatment. Conclusions: Our results support the long-term efficacy and low morbidity of repeat GK treatment for selected patients with tumor growth after initial treatment. PMID:26500799

  3. Gamma Knife

    MedlinePlus

    ... results are sent to the Gamma Knife®'s planning computer system. Together, physicians ( radiation oncologists and neurosurgeons) and medical physicists delineate targets and normal anatomical structures. They use a planning computer program to determine the exact spatial relationship between ...

  4. Ruptured Pseudoaneurysm after Gamma Knife Surgery for Vestibular Schwannoma

    PubMed Central

    MURAKAMI, Mamoru; KAWARABUKI, Kentaro; INOUE, Yasuo; OHTA, Tsutomu

    2016-01-01

    Ruptured aneurysms of anterior inferior cerebellar artery (AICA) after radiotherapy for vestibular schwannoma (VS) are rare, and no definite treatment has been established for distal AICA pseudoaneurysms. We describe a 61-year-old man who underwent Gamma Knife surgery (GKS) for left VS. Follow-up magnetic resonance imaging (MRI) revealed partial regression of the tumor. Twelve years after GKS, he suffered from subarachnoid hemorrhage. Initial angiogram showed no vascular lesions; second left vertebral angiogram, 10 days after admission, demonstrated a pseudoaneurysm in the lateral pontine segment of the left AICA. The proximal portion of the AICA was occluded by a coil. Postoperative MRI revealed an infarction on the left side of the pons and brachium pontis. Although the patient suffered from mild postoperative cerebellar ataxia and facial and abducens nerve palsy, he was discharged 1 month postoperatively requiring no assistance with activities of daily living. Twelve months later, he recovered satisfactorily with a modified Rankin Scale grade of 1, and no recanalization of the aneurysm was found on MR angiography. Endovascular parent artery occlusion for ruptured aneurysms at distal AICA carries the risk of brain stem infarction, but should be considered when no other option is available such as after radiotherapy for VS. PMID:26667081

  5. Gamma knife surgery for epilepsy related to hypothalamic hamartomas.

    PubMed

    Régis, Jean; Scavarda, Didier; Tamura, Manabu; Villeneuve, Nathalie; Bartolomei, Fabrice; Brue, Thierry; Morange, Isabelle; Dafonseca, David; Chauvel, Patrick

    2007-06-01

    Numerous neurosurgical approaches are available for children presenting with hypothalamic hamartomas (HHs) associated with severe epilepsy. A concern regarding the impairment of short-term memory after resective surgery is promoting the exploration of less invasive alternatives like radiosurgery. Gamma knife radiosurgery (GKS) can lead to a real reversal of the epileptic encephalopathy. Three years after radiosurgery, 60% of the children have an excellent result with complete seizure cessation in 40% and rare nondisabling seizures in 20%, often in association with dramatic behavioral and cognitive improvement. No permanent neurologic complications have thus far been reported. Rare transient cases of poikilothermia have been observed. GKS is clearly the safer approach for these difficult patients. Young patients with severe epilepsy and neurocognitive comorbidity must be treated by using a curative approach as early as possible. Topological type (according to our original classification) is the major feature for selection of the best treatment strategy. Type I HH deeply embedded in the hypothalamus is treated safely and efficiently by GKS. Type II HH can be resected by either endoscopic or transcallosal approaches or treated by GKS depending on the parent's choice and severity of epilepsy. In small type III HH, GKS is the safer procedure because of the very close relationship to the fornix and mammillary bodies. Types V (rarely epileptic) and IV are frequently operable by disconnection. Very large type VI (or mixed type) with a large component above the floor of the third ventricle must be disconnected, and then the upper remnant is best treated by GKS using a staged technique. Overall, when the lesion is sufficiently small, GKS offers a rate of seizure control comparable to microsurgery but with much lower risk. The disadvantage of radiosurgery is its delayed action. Longer follow-up is mandatory for a reliable evaluation of the role of GKS. PMID:17544950

  6. An intermediate term benefits and complications of gamma knife surgery in management of glomus jugulare tumor.

    PubMed

    Hafez, Raef F A; Morgan, Magad S; Fahmy, Osama M

    2016-01-01

    Glomus tumors are rare skull base slow-growing, hypervascular neoplasms that frequently involve critical neurovascular structures, and delay in diagnosis is frequent. Surgical removal is rarely radical and is usually associated with morbidity or mortality. Gamma knife surgery (GKS) has gained an increasing dependable role in the management of glomus jugulare tumors, with high rate of tumor growth control, preserving or improving clinical status and with limited complications. This study aims to evaluate intermediate term benefits and complications of gamma knife surgery in management of twenty-two patients bearing growing glomus jugulare tumors at the International Medical Center (IMC), Cairo, Egypt, between 2005 and 2011. The mean follow-up period was 56 months (range 36-108 months); there were 3 males, 19 females; mean age was 43.6 years; 15 patients had GKS as the primary treatment; 2 patients had surgical residuals; 2 had previous radiation therapy; and 3 previously underwent endovascular embolization. The average tumor volume was 7.26 cm3, and the mean marginal dose was 14.7 Gy. Post gamma knife surgery through the follow-up period neurological status was improved in 12 patients, 7 showed stable clinical condition and 3 patients developed new moderate deficits. Tumor volume post GKS was unchanged in 13 patients, decreased in 8, and showed tumor regrowth in 1 patient. Tumor progression-free survival in our studied patients was 95.5% at 5 and 7 years of the follow-up period post GKS. Gamma knife surgery could be used safely and effectively with limited complications as a primary management tool in the treatment of glomus jugulare tumors controlling tumor growth with preserving or improving clinical status especially those who do not have significant cranial or cervical extension, elderly, and surgically unfit patients; moreover, it is safe and highly effective as adjuvant therapy as well. PMID:26879488

  7. Dynamic gamma knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Luan, Shuang; Swanson, Nathan; Chen, Zhe; Ma, Lijun

    2009-03-01

    Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C™ and Perfexion™ units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can obtain a family of plans representing a tradeoff between the delivery time and the

  8. Gamma knife surgery for a hemangioma of the cavernous sinus in a child.

    PubMed

    Murphy, Rory K J; Reynolds, Matthew R; Mansur, David B; Smyth, Matthew D

    2013-01-01

    Cavernous sinus (CS) hemangiomas are rare vascular abnormalities that constitute 0.4%-2% of all lesions within the CS. Cavernous sinus hemangiomas are high-flow vascular tumors that tend to hemorrhage profusely during resection, leading to incomplete resection and high morbidity and mortality. While Gamma Knife surgery (GKS) has proven to be an effective treatment of CS hemangiomas in the adult population, few reports of GKS for treatment of CS hemangiomas exist in the pediatric literature. Here, the authors present the first case of a 15-year-old girl with a biopsy-proven CS hemangioma who achieved complete resolution of her symptoms and a complete imaging-defined response following GKS. If suspicion for a CS hemangioma is high in a pediatric patient, GKS may be considered as an effective treatment modality, thus avoiding the morbidities of open resection. PMID:23082966

  9. [Two patients having recurrent breast cancer with brain metastases well controlled with a gamma knife radio-surgery].

    PubMed

    Hojo, Shigeyuki; Maeura, Yoshiichi; Yoshioka, Setsuko; Fujie, Yujiro; Fukunaga, Hiroki; Okada, Yoshihiro; Ota, Hirofumi; Endo, Wakio

    2006-11-01

    We report two patients having recurrent breast cancer with brain metastases that was controlled well with a gamma knife radio-surgery. The patient is a 50-year-old woman. She underwent radical mastectomy for right breast cancer in September 1993. She suffered from multiple liver metastases in June 2000, so CEF therapy contained hepatic arterial infusion chemotherapy, and extended right lobectomy of the liver were performed in December 2001. Afterward, pleurodesis was carried out to the carcinomatous pleurisy. Then she underwent simple total hysterectomy and bilateral oophorectomy for torsion of the metastatic ovarian tumor. MRI study revealed brain metastases with a diameter of 1 cm in her right midbrain in April 2005, so a gamma knife radio-surgery was performed. After the radio-surgery, a weekly paclitaxel therapy followed by peroral chemotherapy with capecitabine was started, and she took the regimen continuously. Another patient is a 56-year-old woman. She underwent skin sparing mastectomy with axillary lymph node dissection for right breast cancer in November 2002. Metastases to the base of her skull were found in October 2004, so a gamma knife radio-surgery was carried out. After the radio-surgery, a weekly paclitaxel therapy with anastrozole was started. In both of the two patients, the metastatic brain tumors have not shown growth so far and are under good control as of March 2006. PMID:17212144

  10. Acute necrosis after Gamma Knife surgery in vestibular schwannoma leading to multiple cranial nerve palsies.

    PubMed

    Kapitza, Sandra; Pangalu, Athina; Horstmann, Gerhard A; van Eck, Albert T; Regli, Luca; Tarnutzer, Alexander A

    2016-08-01

    We discuss a rare acute complication after Gamma Knife therapy (Elekta AB, Stockholm, Sweden) in a single patient. A 52-year-old woman presented with vertigo, facial weakness and hearing loss emerging 48hours following Gamma Knife radiosurgery for a right-sided vestibular schwannoma. Neurological examination 6days after symptom onset showed right-sided facial palsy, spontaneous left-beating nystagmus and pathologic head-impulse testing to the right. Pure-tone audiogram revealed right-sided sensorineural hearing loss. A diagnosis of acute vestibulocochlear and facial neuropathy was made. Brain MRI demonstrated focal contrast sparing within the schwannoma, likely related to acute radiation necrosis. Acute multiple cranial neuropathies of the cerebellopontine angle after Gamma Knife treatment should raise suspicion of acute tissue damage within the schwannoma and should result in urgent MRI. Treatment with steroids may be considered based on accompanying swelling and edema. PMID:26947104

  11. Long-Term Results for Trigeminal Schwannomas Treated With Gamma Knife Surgery

    SciTech Connect

    Hasegawa, Toshinori Kato, Takenori; Iizuka, Hiroshi; Kida, Yoshihisa

    2013-12-01

    Purpose: Surgical resection is considered the desirable curative treatment for trigeminal schwannomas. However, complete resection without any complications remains challenging. During the last several decades, stereotactic radiosurgery (SRS) has emerged as a minimally invasive treatment modality. Information regarding long-term outcomes of SRS for patients harboring trigeminal schwannomas is limited because of the rarity of this tumor. The aim of this study was to evaluate long-term tumor control and functional outcomes in patients harboring trigeminal schwannomas treated with SRS, specifically with gamma knife surgery (GKS). Methods and Materials: Fifty-three patients harboring trigeminal schwannomas treated with GKS were evaluated. Of these, 2 patients (4%) had partial irradiation of the tumor, and 34 patients (64%) underwent GKS as the initial treatment. The median tumor volume was 6.0 cm{sup 3}. The median maximum and marginal doses were 28 Gy and 14 Gy, respectively. Results: The median follow-up period was 98 months. On the last follow-up image, 7 patients (13%) had tumor enlargement, including the 2 patients who had partial treatment. Excluding the 2 patients who had partial treatment, the actuarial 5- and 10-year progression-free survival (PFS) rates were 90% and 82%, respectively. Patients with tumors compressing the brainstem with deviation of the fourth ventricle had significantly lower PFS rates. If those patients with tumors compressing the brainstem with deviation of the fourth ventricle are excluded, the actuarial 5- and 10-year PFS rates increased to 95% and 90%, respectively. Ten percent of patients had worsened facial numbness or pain in spite of no tumor progression, indicating adverse radiation effect. Conclusions: GKS can be an acceptable alternative to surgical resection in patients with trigeminal schwannomas. However, large tumors that compress the brainstem with deviation of the fourth ventricle should be surgically removed first and then

  12. Biphasic response of a tecto-mesencephalic pilocytic astrocytoma after Gamma Knife surgery--A case report.

    PubMed

    Tuleasca, C; Negretti, L; Magaddino, V; Maeder, P; Lhermitte, B; Borruat, F-X; Levivier, M

    2015-08-01

    Biphasic response (shrinkage-regrowth-shrinkage) of tumors has never previously been reported in the postoperative course, neither after microsurgery, nor after Gamma Knife surgery (GKS). We present the case of an adult with dorsal midbrain syndrome resulting from a pilocytic astrocytoma centered on the mesencephalic tectum. The tumor extended to the third ventricle and the thalamus. Initially, due to tumor growth, a biopsy was performed and histology established. Later, a ventriculocisternostomy for obstructive hydrocephalus was performed. Finally, GKS was performed, as the tumor continued to grow. After GKS, the lesion exhibited a biphasic response, with a major shrinkage at 3 months, regrowth within the target volume at 6 and 9 months and a second phase of important shrinkage at 12 months, which persisted for the next two years. The possible mechanisms for this particular response pattern are discussed. PMID:26072229

  13. Development of Dose-Volume Relation Model for Gamma Knife Surgery of Non-Skull Base Intracranial Meningiomas

    SciTech Connect

    Chung, H.-T.; Kim, Dong Gyu Paek, Sun Ha; Jung, Hee-Won

    2009-07-15

    Purpose: To provide a dose-volume relationship for gamma knife surgery (GKS) of non-skull base intracranial meningiomas. Methods and Materials: The radiologic outcomes of GKS of 82 imaging-defined benign meningiomas located at non-skull base areas were analyzed. A total of 80 patients were included and all underwent treatment with GKS as the first and the only treatment modality. The mean patient age was 55.0 years (range, 26-78) and the mean tumor volume was 5.6 cm{sup 3} (range, 0.5-16.8). On average, 14.6 Gy (range, 10-20) was applied to the 50% isodose surface. The binary logistic regression method was applied to find prognostic factors of signal change (SC) on T{sub 2}-weighted magnetic resonance imaging after GKS. Results: The actuarial tumor control rate was 91.6% at 5 years. A total of 29 lesions (35.4%) showed newly developed or aggravated SCs. The volume irradiated {>=}14 Gy was the only statistically significant (p < .01) prognostic factor of SC. A dose-volume relation model obtained from the cases without SC estimated a 12.2% SC probability. Conclusion: This model can be used in GKS to treat small- to medium-size (<9.2 cm{sup 3}) non-skull base meningiomas.

  14. A Simple and Efficient Methodology To Improve Geometric Accuracy in Gamma Knife Radiation Surgery: Implementation in Multiple Brain Metastases

    SciTech Connect

    Karaiskos, Pantelis; Moutsatsos, Argyris; Pappas, Eleftherios; Georgiou, Evangelos; Roussakis, Arkadios; Torrens, Michael; Seimenis, Ioannis

    2014-12-01

    Purpose: To propose, verify, and implement a simple and efficient methodology for the improvement of total geometric accuracy in multiple brain metastases gamma knife (GK) radiation surgery. Methods and Materials: The proposed methodology exploits the directional dependence of magnetic resonance imaging (MRI)-related spatial distortions stemming from background field inhomogeneities, also known as sequence-dependent distortions, with respect to the read-gradient polarity during MRI acquisition. First, an extra MRI pulse sequence is acquired with the same imaging parameters as those used for routine patient imaging, aside from a reversal in the read-gradient polarity. Then, “average” image data are compounded from data acquired from the 2 MRI sequences and are used for treatment planning purposes. The method was applied and verified in a polymer gel phantom irradiated with multiple shots in an extended region of the GK stereotactic space. Its clinical impact in dose delivery accuracy was assessed in 15 patients with a total of 96 relatively small (<2 cm) metastases treated with GK radiation surgery. Results: Phantom study results showed that use of average MR images eliminates the effect of sequence-dependent distortions, leading to a total spatial uncertainty of less than 0.3 mm, attributed mainly to gradient nonlinearities. In brain metastases patients, non-eliminated sequence-dependent distortions lead to target localization uncertainties of up to 1.3 mm (mean: 0.51 ± 0.37 mm) with respect to the corresponding target locations in the “average” MRI series. Due to these uncertainties, a considerable underdosage (5%-32% of the prescription dose) was found in 33% of the studied targets. Conclusions: The proposed methodology is simple and straightforward in its implementation. Regarding multiple brain metastases applications, the suggested approach may substantially improve total GK dose delivery accuracy in smaller, outlying targets.

  15. Long-term safety and efficacy of Gamma Knife surgery in classical trigeminal neuralgia: a 497-patient historical cohort study.

    PubMed

    Régis, Jean; Tuleasca, Constantin; Resseguier, Noémie; Carron, Romain; Donnet, Anne; Gaudart, Jean; Levivier, Marc

    2016-04-01

    OBJECT Gamma Knife surgery (GKS) is one of the surgical alternatives for the treatment of drug-resistant trigeminal neuralgia (TN). This study aims to evaluate the safety and efficacy of GKS in a large population of patients with TN with very long-term clinical follow-up. METHODS Between July 1992 and November 2010, 737 patients presenting with TN were treated using GKS. Data were collected prospectively and were further retrospectively evaluated at Timone University Hospital. The frequency and severity of pain, as well as trigeminal nerve function, were evaluated before GKS and regularly thereafter. Radiosurgery using the Gamma Knife (model B, C, 4C, or Perfexion) was performed with the help of both MR and CT targeting. A single 4-mm isocenter was positioned in the cisternal portion of the trigeminal nerve at a median distance of 7.6 mm (range 4-14 mm) anterior to the emergence of the nerve (retrogasserian target). A median maximum dose of 85 Gy (range 70-90 Gy) was prescribed. RESULTS The safety and efficacy are reported for 497 patients with medically refractory classical TN who were never previously treated by GKS and had a follow-up of at least 1 year. The median age in this series was 68.3 years (range 28.1-93.2 years). The median follow-up period was 43.8 months (range 12-174.4 months). Overall, 456 patients (91.75%) were initially pain free in a median time of 10 days (range 1-180 days). Their actuarial probabilities of remaining pain free without medication at 3, 5, 7, and 10 years were 71.8%, 64.9%, 59.7%, and 45.3%, respectively. One hundred fifty-seven patients (34.4%) who were initially pain free experienced at least 1 recurrence, with a median delay of onset of 24 months (range 0.6-150.1 months). However, the actuarial rate of maintaining pain relief without further surgery was 67.8% at 10 years. The hypesthesia actuarial rate at 5 years was 20.4% and at 7 years reached 21.1%, but remained stable until 14 years with a median delay of onset of 12

  16. Predictive Nomogram for the Durability of Pain Relief From Gamma Knife Radiation Surgery in the Treatment of Trigeminal Neuralgia

    SciTech Connect

    Lucas, John T.; Nida, Adrian M.; Isom, Scott; Marshall, Kopriva; Bourland, John D.; Laxton, Adrian W.; Tatter, Stephen B.; Chan, Michael D.

    2014-05-01

    Purpose: To determine factors associated with the durability of stereotactic radiation surgery (SRS) for treatment of trigeminal neuralgia (TN). Methods and Materials: Between 1999 and 2008, 446 of 777 patients with TN underwent SRS and had evaluable follow-up in our electronic medical records and phone interview records. The median follow-up was 21.2 months. The Barrow Neurologic Institute (BNI) pain scale was used to determine pre- and post-SRS pain. Dose-volume anatomical measurements, Burchiel pain subtype, pain quality, prior procedures, and medication usage were included in this retrospective cohort to identify factors impacting the time to BNI 4-5 pain relapse by using Cox proportional hazard regression. An internet-based nomogram was constructed based on predictive factors of durable relief pre- and posttreatment at 6-month intervals. Results: Rates of freedom from BNI 4-5 failure at 1, 3, and 5 years were 84.5%, 70.4%, and 46.9%, respectively. Pain relief was BNI 1-3 at 1, 3, and 5 years in 86.1%, 74.3%, and 51.3% of type 1 patients; 79.3%, 46.2%, and 29.3% of type 2 patients; and 62.7%, 50.2%, and 25% of atypical facial pain patients. BNI type 1 pain score was achieved at 1, 3, and 5 years in 62.9%, 43.5%, and 22.0% of patients with type 1 pain and in 47.5%, 25.2%, and 9.2% of type 2 patients, respectively. Only 13% of patients with atypical facial pain achieved BNI 1 response; 42% of patients developed post-Gamma Knife radiation surgery (GKRS) trigeminal dysfunction. Multivariate analysis revealed that post-SRS numbness (hazard ratio [HR], 0.47; P<.0001), type 1 (vs type 2) TN (HR, 0.6; P=.02), and improved post-SRS BNI score at 6 months (HR, 0.009; P<.0001) were predictive of a durable pain response. Conclusions: The durability of SRS for TN depends on the presenting Burchiel pain type, the post-SRS BNI score, and the presence of post-SRS facial numbness. The durability of pain relief can be estimated pre- and posttreatment by using our

  17. Development of anterior inferior cerebellar artery pseudoaneurysm after gamma knife surgery for vestibular schwannoma. A case report and review of the literature.

    PubMed

    Sunderland, Geraint; Hassan, Faizul; Bhatnagar, Priya; Mitchell, Patrick; Jayakrishnan, Vijayam; Forster, David; Mendelow, Alexander David

    2014-08-01

    Gamma knife surgery (GKS) is a well-established modality for controlling the progression of vestibular schwannomas. Adverse effects of this treatment are extremely rare but include cyst formation and malignant transformation. We report a case of anterior inferior cerebellar artery (AICA) pseudoaneurysm development rupture presenting as a poor WFNS grade subarachnoid haemorrhage. This is only the fourth case of aneurysm development (AICA aneurysm) following GKS reported but due to its serious nature we believe this potential complication warrants awareness in those offering this treatment. PMID:24111706

  18. Treatment of epidermoid tumors with gamma knife radiosurgery: Case series

    PubMed Central

    Vasquez, Javier A. Jacobo; Fonnegra, Julio R.; Diez, Juan C.; Fonnegra, Andres

    2016-01-01

    Background: Epidermoid tumors (ETs) are benign lesions that are treated mainly by means of surgical resection, with overall good results. External beam radiotherapy is an alternative treatment for those recurrent tumors, in which a second surgery might not be the best choice for the patient. A little information exists about the effectiveness of gamma knife radiosurgery for the treatment of newly diagnosed and recurrent ETs. We present three cases of ETs treated with gamma knife radiosurgery. Case Description: Case 1 is a 21-year-old female with an ET located in the left cerebellopontine angle (CPA) with symptoms related to VIII cranial nerve dysfunction. Symptom control was achieved and maintained after single session radiosurgery with gamma knife. Case 2 is a 59-year-old female patient with the history of trigeminal neuralgia secondary to a recurrent ET located in the left CPA. Significant pain improvement was achieved after treatment with gamma knife radiosurgery. Case 3 is a 29-year-old male patient with a CPA ET causing long lasting trigeminal neuralgia, pain relief was achieved in this patient after gamma knife radiosurgery. Conclusion: Long-term symptom relief was achieved in all three cases proving that gamma knife radiosurgery is a good and safe alternative for patients with recurrent or nonsurgically treated ETs. PMID:26958427

  19. Gamma knife radiosurgery for pituitary adenomas.

    PubMed

    Ježková, Jana; Marek, Josef

    2016-09-01

    Pituitary adenomas are frequently occurring intracranial neoplasms. The aim of the treatment of pituitary adenomas is to normalize hormonal hypersecretion, to preserve the normal pituitary function, to reserve or treat impaired pituitary function and to control tumor growth and its mechanical effects on the surrounding structures. Treatment modalities include surgical, medical and radiation therapy. Radiosurgery is mainly used as a secondary line treatment after surgery for residual or recurrent tumors. The antiproliferative effect is achieved by LKG irradiation in more than 90% of patients. Regarding the functioning pituitary adenomas, the manifestation of the treatment effect is slow and depends mainly on the type of adenoma. Gamma knife irradiation is safe when the maximal doses to pituitary and infundibulum are respected. PMID:26899535

  20. The technical evolution of gamma knife radiosurgery for arteriovenous malformations.

    PubMed

    Lunsford, L Dade; Niranjan, Ajay; Kano, Hideyuki; Kondziolka, Douglas

    2013-01-01

    Gamma Knife stereotactic radiosurgery was first applied for the treatment of an intracranial arteriovenous malformation (AVM) in 1968. Using biplane angiography to target a small-volume, deep-seated lesion, photons were cross-fired on the pathological shunt. The AVM was obliterated within 3 years. This began a cautious introduction of Gamma Knife radiosurgery in the 1970s. As the Gamma Knife technology spread to sites in Europe, South America and the USA in the 1980s, AVM radiosurgery became a primary indication. During the early years the usual standard was to deliver a single radiosurgical isocenter to the target defined by 2-dimensional angiography. Most patients had small-volume AVMs unsuitable for surgical excision. Over time the technique of Gamma Knife AVM surgery evolved to include: careful patient selection, discussion of appropriate treatment strategies, anticonvulsant administration for lobar locations and intraoperative targeting using both high-resolution axial plane imaging--usually magnetic resonance imaging--coupled with biplane digital subtraction angiography. High-speed computer dose planning integrated with more detailed imaging strategies facilitated conformal radiation delivery in a single treatment session coupled with high selectivity of the dose delivered. Multiple isocenters became routine. Long-term follow-up care included serial imaging evaluations to assess the response and to detect complications. Imaging was critical to confirm the desired radiobiological response--complete obliteration. Long-term follow-up after obliteration confirmed that AVM radiosurgery had a high success rate for properly selected patients and a risk-benefit profile that substantiated patient safety. Twenty-year results after Gamma Knife radiosurgery for AVMs are currently available. Established roles have been found for pediatric cases and for larger-volume AVMs unsuitable for surgical removal. The role and technique of embolization prior to radiosurgery continue

  1. Gamma Knife Radiosurgery for Choroidal Hemangioma

    SciTech Connect

    Kim, Yun Taek; Kang, Se Woong; Lee, Jung-Il

    2011-12-01

    Purpose: Patients with choroidal hemangioma (CH), a benign ocular hamartoma, frequently presents with visual disturbance as a result of exudative retinal detachment (RD), which originates in subretinal fluid accumulation. We report our experience using the Leksell Gamma Knife in the management of symptomatic CH. Methods and Materials: Seven patients with symptomatic CH (circumscribed form in 3 patients and diffuse form in 4) were treated with the Leksell Gamma Knife at our institution during a 7-year period. All patients presented with exudative RD involving the macula that resulted in severe visual deterioration. The prescription dose to the target margin was 10 Gy in all cases. The mean tumor volume receiving the prescription dose was 536 mm{sup 3} (range, 151-1,057). The clinical data were analyzed in a retrospective fashion after a mean follow-up of 34.4 months (range, 9-76). Results: The resolution of exudative RD was achieved within 6 months, and the visual acuity of the affected eye had improved at the latest follow-up examination (p = .018) in all patients. No recurrence of exudative RD occurred. Thinning of the CHs was observed in most patients; however, symptomatic radiation toxicity had not developed in any of the patients. Conclusion: Symptomatic CHs can be safely and effectively managed with Gamma Knife radiosurgery using a marginal dose of 10 Gy.

  2. Efficacy of stereotactic gamma knife surgery and microvascular decompression in the treatment of primary trigeminal neuralgia: a retrospective study of 220 cases from a single center

    PubMed Central

    Dai, Zi-Feng; Huang, Qi-Lin; Liu, Hai-Peng; Zhang, Wei

    2016-01-01

    Objectives A retrospective study was undertaken to compare the efficacy of stereotactic gamma knife surgery (GKS) and microvascular decompression (MVD) in the treatment of primary trigeminal neuralgia (TN) at a single center. The study included the evaluation of clinical outcomes of pain relief and pain recurrence and complications associated with GKS and MVD. Methods The study included 202 patients with primary TN and was conducted between January 2013 and December 2014; about 115 patients were treated with GKS and 87 patients were treated with MVD. TN pain was evaluated using the Barrow Neurological Institute and the visual analog scale scoring systems. Preoperative magnetic resonance tomographic angiography was performed for all patients. Microscope-assisted MVD used the suboccipital retrosigmoid sinus approach. GKS targeted the trigeminal nerve root entry zone with a margin radiation dose of 59.5 Gy, and brainstem dose <12 Gy. Posttreatment follow-up was for 2 years. Results Postoperative Barrow Neurological Institute scores for patients treated with GKS and MVD were significantly improved compared with preoperative scores (P<0.01). Reduction in postoperative pain following MVD (95.4% patients) was significantly greater than that following GKS (88.7% patients) (P<0.01). Postoperative visual analog scale scores of the MVD group were significantly reduced compared with those of patients treated with GKS at the same postoperative time points (P<0.01). Patients treated with GKS had a significantly increased rate of loss of corneal reflex compared with patients treated with MVD (P=0.002). Conclusion Both GKS and MVD are safe and effective first-line and adjunctive treatment options for patients with TN. The clinical outcomes of pain relief and reduction of pain recurrence were better with MVD. For GKS, this study showed that the optimal radiation therapeutic dose range was 70–90 Gy, but brainstem radiation protection is recommended. PMID:27555796

  3. Semiquantitative Analysis Using Thallium-201 SPECT for Differential Diagnosis Between Tumor Recurrence and Radiation Necrosis After Gamma Knife Surgery for Malignant Brain Tumors

    SciTech Connect

    Matsunaga, Shigeo; Shuto, Takashi; Takase, Hajime; Ohtake, Makoto; Tomura, Nagatsuki; Tanaka, Takahiro; Sonoda, Masaki

    2013-01-01

    Purpose: Semiquantitative analysis of thallium-201 chloride single photon emission computed tomography ({sup 201}Tl SPECT) was evaluated for the discrimination between recurrent brain tumor and delayed radiation necrosis after gamma knife surgery (GKS) for metastatic brain tumors and high-grade gliomas. Methods and Materials: The medical records were reviewed of 75 patients, including 48 patients with metastatic brain tumor and 27 patients with high-grade glioma who underwent GKS in our institution, and had suspected tumor recurrence or radiation necrosis on follow-up neuroimaging and deteriorating clinical status after GKS. Analysis of {sup 201}Tl SPECT data used the early ratio (ER) and the delayed ratio (DR) calculated as tumor/normal average counts on the early and delayed images, and the retention index (RI) as the ratio of DR to ER. Results: A total of 107 tumors were analyzed with {sup 201}Tl SPECT. Nineteen lesions were removed surgically and histological diagnoses established, and the other lesions were evaluated with follow-up clinical and neuroimaging examinations after GKS. The final diagnosis was considered to be recurrent tumor in 65 lesions and radiation necrosis in 42 lesions. Semiquantitative analysis demonstrated significant differences in DR (P=.002) and RI (P<.0001), but not in ER (P=.372), between the tumor recurrence and radiation necrosis groups, and no significant differences between metastatic brain tumors and high-grade gliomas in all indices (P=.926 for ER, P=.263 for DR, and P=.826 for RI). Receiver operating characteristics analysis indicated that RI was the most informative index with the optimum threshold of 0.775, which provided 82.8% sensitivity, 83.7% specificity, and 82.8% accuracy. Conclusions: Semiquantitative analysis of {sup 201}Tl SPECT provides useful information for the differentiation between tumor recurrence and radiation necrosis in metastatic brain tumors and high-grade gliomas after GKS, and the RI may be the most

  4. Gamma knife radiosurgery in 11 hemangioblastomas.

    PubMed

    Niemelä, M; Lim, Y J; Söderman, M; Jääskeläinen, J; Lindquist, C

    1996-10-01

    One suprasellar, one mesencephalic, and nine cerebellar hemangioblastomas were treated with the gamma knife in 10 patients (median age 48 years) in Stockholm between 1978 and 1993. Four patients had von Hippel-Lindau disease, a dominant inherited trait predisposing to multiple hemangioblastomas. Six hemangioblastomas were treated with radiotherapy at a median margin dose of 25 Gy (20-35 Gy) before 1990 and the next five with a median of 10 Gy (5-19 Gy). Computerized tomography or magnetic resonance images were available for 10 of the 11 hemangioblastomas at a median follow-up time of 26 months (4-68 months) after radiosurgery. The solid part of six hemangioblastomas shrank in a median of 30 months, whereas four hemangioblastomas were unchanged at a median of 14 months. Five hemangioblastomas had an adjoining cyst and three of these cysts had to be evacuated after radiosurgery. One solitary hemangioblastoma later developed a de novo cyst that also needed evacuation. One patient with two cerebellar hemangioblastomas (margin dose 25 Gy each) developed edema at 6 months and required a shunt and prolonged corticosteroid treatment. The combined follow-up data of the 23 hemangioblastomas in 15 patients from previous literature and the present series indicate that, first, a solitary small- or medium-sized hemangioblastoma usually shrinks or stops growing after radiosurgery. The recommended margin dose is 10 to 15 Gy. Second, the adjoining cyst often does not respond to radiosurgery but requires later, sometimes repeated evacuation. PMID:8814161

  5. Gamma Knife radiosurgery for intracranial hemangioblastoma.

    PubMed

    Silva, Danilo; Grabowski, Mathew M; Juthani, Rupa; Sharma, Mayur; Angelov, Lilyana; Vogelbaum, Michael A; Chao, Samuel; Suh, John; Mohammadi, Alireza; Barnett, Gene H

    2016-09-01

    Gamma knife radiosurgery (GKRS) has become a treatment option for intracranial hemangioblastomas, especially in patients with poor clinical status and also high-risk surgical candidates. The objective of this study was to analyze clinical outcome and tumor control rates. Retrospective chart review revealed 12 patients with a total of 20 intracranial hemangioblastomas treated with GKRS from May 1998 until December 2014. Kaplan-Meier plots were used to calculate the actuarial local tumor control rates and rate of recurrence following GKRS. Univariate analysis, including log rank test and Wilcoxon test were used on the Kaplan-Meier plots to evaluate the predictors of tumor progression. Two-tailed p value of <0.05 was considered as significant. Median follow-up was 64months (2-184). Median tumor volume pre-GKRS was 946mm(3) (79-15970), while median tumor volume post-GKRS was 356mm(3) (30-5404). Complications were seen in two patients. Tumor control rates were 100% at 1year, 90% at 3years, and 85% at 5years, using the Kaplan-Meier method. There were no statistically significant univariate predictors of progression identified, although there was a trend towards successful tumor control in solid tumors (p=0.07). GKRS is an effective and safe option for treating intracranial hemangioblastoma with favorable tumor control rates. PMID:27422585

  6. Repeat Gamma Knife Radiosurgery for Trigeminal Neuralgia

    SciTech Connect

    Aubuchon, Adam C.; Chan, Michael D.; Lovato, James F.; Balamucki, Christopher J.; Ellis, Thomas L.; Tatter, Stephen B.; McMullen, Kevin P.; Munley, Michael T.; Deguzman, Allan F.; Ekstrand, Kenneth E.; Bourland, J. Daniel; Shaw, Edward G.

    2011-11-15

    Purpose: Repeat gamma knife stereotactic radiosurgery (GKRS) for recurrent or persistent trigeminal neuralgia induces an additional response but at the expense of an increased incidence of facial numbness. The present series summarized the results of a repeat treatment series at Wake Forest University Baptist Medical Center, including a multivariate analysis of the data to identify the prognostic factors for treatment success and toxicity. Methods and Materials: Between January 1999 and December 2007, 37 patients underwent a second GKRS application because of treatment failure after a first GKRS treatment. The mean initial dose in the series was 87.3 Gy (range, 80-90). The mean retreatment dose was 84.4 Gy (range, 60-90). The dosimetric variables recorded included the dorsal root entry zone dose, pons surface dose, and dose to the distal nerve. Results: Of the 37 patients, 81% achieved a >50% pain relief response to repeat GKRS, and 57% experienced some form of trigeminal dysfunction after repeat GKRS. Two patients (5%) experienced clinically significant toxicity: one with bothersome numbness and one with corneal dryness requiring tarsorraphy. A dorsal root entry zone dose at repeat treatment of >26.6 Gy predicted for treatment success (61% vs. 32%, p = .0716). A cumulative dorsal root entry zone dose of >84.3 Gy (72% vs. 44%, p = .091) and a cumulative pons surface dose of >108.5 Gy (78% vs. 44%, p = .018) predicted for post-GKRS numbness. The presence of any post-GKRS numbness predicted for a >50% decrease in pain intensity (100% vs. 60%, p = .0015). Conclusion: Repeat GKRS is a viable treatment option for recurrent trigeminal neuralgia, although the patient assumes a greater risk of nerve dysfunction to achieve maximal pain relief.

  7. Anomalous primary radiation from the Leksell Gamma Knife Unit.

    PubMed

    Shearer, D R; Roventine, W A; Coy, S R

    1994-12-01

    The Leksell Gamma Knife Unit, Type U, utilizes 201 separate 60Co sources intersecting at a common focus for radiosurgical treatment of the brain. It has been generally understood that all primary unattenuated radiation beams are confined within the protective housing during all phases of Gamma Knife operation. We have found that when the unit's shielding door is lowered for treatment, twelve primary beams exit the unit's door opening. Furthermore, in the original Gamma Knife unit design, two of the twelve primary beams failed to be attenuated by either the unit base or the unit wings. This has implications for the design of structural shielding and the protection of personnel during emergency procedures. Engineering modifications to eliminate the problem are discussed. PMID:7960787

  8. Peripheral dose in ocular treatments with CyberKnife and Gamma Knife radiosurgery compared to proton radiotherapy

    NASA Astrophysics Data System (ADS)

    Zytkovicz, A.; Daftari, I.; Phillips, T. L.; Chuang, C. F.; Verhey, L.; Petti, P. L.

    2007-09-01

    Peripheral radiation can have deleterious effects on normal tissues throughout the body, including secondary cancer induction and cataractogenesis. The aim of this study is to evaluate the peripheral dose received by various regions of the body after ocular treatment delivered with the Model C Gamma Knife, proton radiotherapy with a dedicated ocular beam employing no passive-scattering system, or a CyberKnife unit before and after supplemental shielding was introduced. TLDs were used for stray gamma and x-ray dosimetry, whereas CR-39 dosimeters were used to measure neutron contamination in the proton experiments. Doses to the contralateral eye, neck, thorax and abdomen were measured on our anthropomorphic phantom for a 56 Gy treatment to a 588 mm3 posterior ocular lesion. Gamma Knife (without collimator blocking) delivered the highest dose in the contralateral eye, with 402-2380 mSv, as compared with 118-234 mSv for CyberKnife pre-shielding, 46-255 mSv for CyberKnife post-shielding and 9-12 mSv for proton radiotherapy. Gamma Knife and post-shielding CyberKnife delivered comparable doses proximal to the treatment site, with 190 versus 196 mSv at the thyroid, whereas protons doses at these locations were less than 10 mSv. Gamma Knife doses decreased dramatically with distance from the treatment site, delivering only 13 mSv at the lower pelvis, comparable to the proton result of 4 to 7 mSv in this region. In contrast, CyberKnife delivered between 117 and 132 mSv to the lower pelvis. In conclusion, for ocular melanoma treatments, a proton beam employing no double scattering system delivers the lowest peripheral doses proximally to the contralateral eye and thyroid when compared to radiosurgery with the Model C Gamma Knife or CyberKnife. At distal locations in the pelvis, peripheral doses delivered with proton and Gamma Knife are of an order of magnitude smaller than those delivered with CyberKnife.

  9. Peripheral dose in ocular treatments with CyberKnife and Gamma Knife radiosurgery compared to proton radiotherapy.

    PubMed

    Zytkovicz, A; Daftari, I; Phillips, T L; Chuang, C F; Verhey, L; Petti, P L

    2007-10-01

    Peripheral radiation can have deleterious effects on normal tissues throughout the body, including secondary cancer induction and cataractogenesis. The aim of this study is to evaluate the peripheral dose received by various regions of the body after ocular treatment delivered with the Model C Gamma Knife, proton radiotherapy with a dedicated ocular beam employing no passive-scattering system, or a CyberKnife unit before and after supplemental shielding was introduced. TLDs were used for stray gamma and x-ray dosimetry, whereas CR-39 dosimeters were used to measure neutron contamination in the proton experiments. Doses to the contralateral eye, neck, thorax and abdomen were measured on our anthropomorphic phantom for a 56 Gy treatment to a 588 mm(3) posterior ocular lesion. Gamma Knife (without collimator blocking) delivered the highest dose in the contralateral eye, with 402-2380 mSv, as compared with 118-234 mSv for CyberKnife pre-shielding, 46-255 mSv for CyberKnife post-shielding and 9-12 mSv for proton radiotherapy. Gamma Knife and post-shielding CyberKnife delivered comparable doses proximal to the treatment site, with 190 versus 196 mSv at the thyroid, whereas protons doses at these locations were less than 10 mSv. Gamma Knife doses decreased dramatically with distance from the treatment site, delivering only 13 mSv at the lower pelvis, comparable to the proton result of 4 to 7 mSv in this region. In contrast, CyberKnife delivered between 117 and 132 mSv to the lower pelvis. In conclusion, for ocular melanoma treatments, a proton beam employing no double scattering system delivers the lowest peripheral doses proximally to the contralateral eye and thyroid when compared to radiosurgery with the Model C Gamma Knife or CyberKnife. At distal locations in the pelvis, peripheral doses delivered with proton and Gamma Knife are of an order of magnitude smaller than those delivered with CyberKnife. PMID:17881812

  10. Fractionated Stereotactic Gamma Knife Radiosurgery for Medial Temporal Lobe Epilepsy: A Case Report

    PubMed Central

    Park, Hye Ran; Chung, Hyun-Tai; Lee, Sang Kun; Kim, Dong Gyu

    2016-01-01

    An 18-year-old left-handed male harbored intractable medial temporal lobe epilepsy (MTLE) underwent fractionated gamma knife surgery (GKS) instead of open surgery, considering the mental retardation and diffuse cerebral dysfunction. GKS treatment parameters were: target volume, 8.8 cm3; total marginal dose, 24 Gy in 3 fractionations at the 50% isodose line. The patient has been free from seizures since 9 months after GKS, with notable improvement in cognitive outcome. Fractionated GKS could be considered as a safe tool for seizure control and neuropsychological improvement in patients with MTLE. PMID:27122996

  11. Fractionated Stereotactic Gamma Knife Radiosurgery for Medial Temporal Lobe Epilepsy: A Case Report.

    PubMed

    Park, Hye Ran; Chung, Hyun-Tai; Lee, Sang Kun; Kim, Dong Gyu; Paek, Sun Ha

    2016-04-01

    An 18-year-old left-handed male harbored intractable medial temporal lobe epilepsy (MTLE) underwent fractionated gamma knife surgery (GKS) instead of open surgery, considering the mental retardation and diffuse cerebral dysfunction. GKS treatment parameters were: target volume, 8.8 cm(3); total marginal dose, 24 Gy in 3 fractionations at the 50% isodose line. The patient has been free from seizures since 9 months after GKS, with notable improvement in cognitive outcome. Fractionated GKS could be considered as a safe tool for seizure control and neuropsychological improvement in patients with MTLE. PMID:27122996

  12. Trochlear Nerve Schwannoma Treated with Gamma Knife after Excision: A Case Report and Review of the Literature

    PubMed Central

    Inoue, Takuro; Shima, Ayako; Hirai, Hisao; Suzuki, Fumio; Matsuda, Masayuki

    2015-01-01

    Trochlear nerve schwannomas are extremely rare. We present a surgically excised case of trochlear nerve schwannoma followed by Gamma Knife (ELEKTA, Stockholm, Sweden) after histologic confirmation. A 52-year-old man presented with diplopia, gait disturbance, and sensory disturbance. Magnetic resonance imaging demonstrated a large cystic mass at ambient cistern on the right side. Subtotal excision followed by Gamma Knife surgery was undertaken. His neurologic symptoms disappeared with radiologic reduction in size at 15-month follow-up. Because Gamma Knife can manage trochlear nerve schwannomas well, surgical excision should be reserved for large ones and limited to subcapsular or subtotal removal with the expectation of possible recovery of neurologic dysfunction. PMID:26623236

  13. Stereotactic radiosurgery of the brain using the first United States 201 cobalt-60 source gamma knife

    SciTech Connect

    Lunsford, L.D.; Flickinger, J.; Lindner, G.; Maitz, A.

    1989-02-01

    The first United States 201 cobalt-60 source gamma knife for stereotactic radiosurgery of brain tumors and arteriovenous malformations became operational at the University of Pittsburgh on August 14, 1987. Four and one-half years of intensive planning, regulatory agency review, and analysis of published results preceded the first radiosurgical procedure. Installation of this 18,000-kg device and loading of the 201 cobalt-60 sources posed major challenges in engineering, architecture, and radiophysics. In the first 4 months of operation, we treated 52 patients (29 with arteriovenous malformations, 19 with extra-axial neoplasms of the skull base, and 4 with intra-axial malignant tumors). Most patients either had lesions considered inoperable or had residual lesions after attempted surgical resection. Neither surgical mortality nor significant morbidity was associated with gamma knife radiosurgery. As compared with treatment by conventional intracranial surgery (craniotomy), the average length of stay for radiosurgery was reduced by 4 to 14 days, and hospital charges were reduced by as much as 65%. Based on both the previously published results of treatment of more than 2,000 patients worldwide and on our initial clinical experience, we believe that gamma knife stereotactic radiosurgery is a therapeutically effective and economically sound alternative to more conventional neurosurgical procedures, in selected cases.

  14. MCNP-based computational model for the Leksell Gamma Knife

    SciTech Connect

    Trnka, Jiri; Novotny, Josef Jr.; Kluson, Jaroslav

    2007-01-15

    We have focused on the usage of MCNP code for calculation of Gamma Knife radiation field parameters with a homogenous polystyrene phantom. We have investigated several parameters of the Leksell Gamma Knife radiation field and compared the results with other studies based on EGS4 and PENELOPE code as well as the Leksell Gamma Knife treatment planning system Leksell GammaPlan (LGP). The current model describes all 201 radiation beams together and simulates all the sources in the same time. Within each beam, it considers the technical construction of the source, the source holder, collimator system, the spherical phantom, and surrounding material. We have calculated output factors for various sizes of scoring volumes, relative dose distributions along basic planes including linear dose profiles, integral doses in various volumes, and differential dose volume histograms. All the parameters have been calculated for each collimator size and for the isocentric configuration of the phantom. We have found the calculated output factors to be in agreement with other authors' works except the case of 4 mm collimator size, where averaging over the scoring volume and statistical uncertainties strongly influences the calculated results. In general, all the results are dependent on the choice of the scoring volume. The calculated linear dose profiles and relative dose distributions also match independent studies and the Leksell GammaPlan, but care must be taken about the fluctuations within the plateau, which can influence the normalization, and accuracy in determining the isocenter position, which is important for comparing different dose profiles. The calculated differential dose volume histograms and integral doses have been compared with data provided by the Leksell GammaPlan. The dose volume histograms are in good agreement as well as integral doses calculated in small calculation matrix volumes. However, deviations in integral doses up to 50% can be observed for large

  15. MCNP-based computational model for the Leksell gamma knife.

    PubMed

    Trnka, Jiri; Novotny, Josef; Kluson, Jaroslav

    2007-01-01

    We have focused on the usage of MCNP code for calculation of Gamma Knife radiation field parameters with a homogenous polystyrene phantom. We have investigated several parameters of the Leksell Gamma Knife radiation field and compared the results with other studies based on EGS4 and PENELOPE code as well as the Leksell Gamma Knife treatment planning system Leksell GammaPlan (LGP). The current model describes all 201 radiation beams together and simulates all the sources in the same time. Within each beam, it considers the technical construction of the source, the source holder, collimator system, the spherical phantom, and surrounding material. We have calculated output factors for various sizes of scoring volumes, relative dose distributions along basic planes including linear dose profiles, integral doses in various volumes, and differential dose volume histograms. All the parameters have been calculated for each collimator size and for the isocentric configuration of the phantom. We have found the calculated output factors to be in agreement with other authors' works except the case of 4 mm collimator size, where averaging over the scoring volume and statistical uncertainties strongly influences the calculated results. In general, all the results are dependent on the choice of the scoring volume. The calculated linear dose profiles and relative dose distributions also match independent studies and the Leksell GammaPlan, but care must be taken about the fluctuations within the plateau, which can influence the normalization, and accuracy in determining the isocenter position, which is important for comparing different dose profiles. The calculated differential dose volume histograms and integral doses have been compared with data provided by the Leksell GammaPlan. The dose volume histograms are in good agreement as well as integral doses calculated in small calculation matrix volumes. However, deviations in integral doses up to 50% can be observed for large

  16. PRESAGE 3D dosimetry accurately measures Gamma Knife output factors

    NASA Astrophysics Data System (ADS)

    Klawikowski, Slade J.; Yang, James N.; Adamovics, John; Ibbott, Geoffrey S.

    2014-12-01

    Small-field output factor measurements are traditionally very difficult because of steep dose gradients, loss of lateral electronic equilibrium, and dose volume averaging in finitely sized detectors. Three-dimensional (3D) dosimetry is ideal for measuring small output factors and avoids many of these potential challenges of point and 2D detectors. PRESAGE 3D polymer dosimeters were used to measure the output factors for the 4 mm and 8 mm collimators of the Leksell Perfexion Gamma Knife radiosurgery treatment system. Discrepancies between the planned and measured distance between shot centers were also investigated. A Gamma Knife head frame was mounted onto an anthropomorphic head phantom. Special inserts were machined to hold 60 mm diameter, 70 mm tall cylindrical PRESAGE dosimeters. The phantom was irradiated with one 16 mm shot and either one 4 mm or one 8 mm shot, to a prescribed dose of either 3 Gy or 4 Gy to the 50% isodose line. The two shots were spaced between 30 mm and 60 mm apart and aligned along the central axis of the cylinder. The Presage dosimeters were measured using the DMOS-RPC optical CT scanning system. Five independent 4 mm output factor measurements fell within 2% of the manufacturer’s Monte Carlo simulation-derived nominal value, as did two independent 8 mm output factor measurements. The measured distances between shot centers varied by ±0.8 mm with respect to the planned shot displacements. On the basis of these results, we conclude that PRESAGE dosimetry is excellently suited to quantify the difficult-to-measure Gamma Knife output factors.

  17. Gamma knife for obsessive compulsive disorder: can it be detrimental?

    PubMed

    Tripathi, Manjul; Mukherjee, Kanchan; Chhabra, Rajesh; Radotra, Ishan; Singh, Apinder P; Radotra, Bishan

    2014-01-01

    Functional neurological disorders (FND) have been a challenge to treat both for neurologists and neurosurgeons. Various ablative as well as non-ablative techniques have been used to treat these disorders. Gamma knife radiosurgery (GKRS) is also being practised to treat refractory obsessive- compulsive disorder (OCD). The subsequent complications of GKRS reported have been variable, with headache being the most common. We discuss here a rare complication of 'late onset radiation necrosis in bilateral caudate nuclei' in a patient after receiving GKRS three years back. This case highlights the need to be more cautious before administering ablative procedures in patients suffering with functional disorders. PMID:25050687

  18. Dosimetrical evaluation of Leksell Gamma Knife 4C radiosurgery unit

    NASA Astrophysics Data System (ADS)

    Sajeev, Thomas; Mustafa, Mohamed M.; Supe, Sanjay S.

    2011-01-01

    A number of experiments was performed using standard protocols, in order to evaluate the dosimetric accuracy of Leksell Gamma Knife 4C unit. Verification of the beam alignment has been performed for all collimators using solid plastic head phantom and Gafchromic™ type MD-55 films. The study showed a good agreement of Leksell Gammaplan calculated dose profiles with experimentally determined profiles in all three axes. Isocentric accuracy is verified using a specially machined cylindrical aluminium film holder tool made with very narrow geometric tolerances aligned between trunnions of 4 mm collimator. Considering all uncertainties in all three dimensions, the estimated accuracy of the unit was 0.1 mm. Dose rate at the centre point of the unit has been determined according to the IAEA, TRS-398 protocol, using Unidose-E (PTW-Freiburg, Germany) with a 0.125 cc ion chamber, over a period of 6 years. The study showed that the Leksell Gamma Knife 4C unit is excellent radiosurgical equipment with high accuracy and precision, which makes it possible to deliver larger doses of radiation, within the limits defined by national and international guidelines, applicable for stereotactic radiosurgery procedures.

  19. Stereotactic gamma knife radiosurgery. Initial North American experience in 207 patients

    SciTech Connect

    Lunsford, L.D.; Flickinger, J.; Coffey, R.J. )

    1990-02-01

    The first North American gamma knife for stereotactic radiosurgery of brain tumors and arteriovenous malformations entered the therapeutic armamentarium at the University of Pittsburgh (Pa) on August 14, 1987. In this article, we report our initial testing and subsequent experience with this technique. In the first 16 months of operation, 207 patients were treated (113 had arteriovenous malformations, 78 had extra-axial skull base neoplasms, 9 had glial neoplasms, and 7 had metastatic tumors). The patients' lesions either were considered previously as inoperable or were residual lesions after attempted surgical resection, or the radiosurgery was performed after the patient declined surgical excision. Gamma radiosurgery was associated with no surgical mortality and no significant early morbidity, and the results were encouraging during the minimum follow-up period of 6 months. Compared with treatment by conventional intracranial surgery (craniotomy), both the average length of stay and hospital charges for radiosurgery were significantly lower. Our initial experience further suggests that stereotactic radiosurgery using the gamma knife is a therapeutically effective and economically sound alternative to microneurosurgical removal of selected intracranial tumors and vascular malformations.

  20. Stereotactic radiosurgery using the gamma knife for acoustic neuromas

    SciTech Connect

    Foote, R.L.; Coffey, R.J.; Swanson, J.W.

    1995-07-15

    The purpose of this investigation was to assess the efficacy and toxicity of stereotactic radiosurgery using the gamma knife for acoustic neuromas. Between January 1990 and January 1993, 36 patients with acoustic neuromas were treated with stereotactic radiosurgery using the gamma knife. The median maximum tumor diameter was 21 mm (range: 6-32 mm). Tumor volumes encompasses within the prescribed isodose line varied from 266 to 8,667 mm{sup 3} (median: 3,135 mm{sup 3}). Tumors {<=} 20 mm in maximum diameter received a dose of 20 Gy to the margin, tumors between 21 and 30 mm received 18 Gy, and tumors > 30 mm received 16 Gy. The dose was prescribed to the 50% isodose line in 31 patients and to the 45%, 55%, 60%, 70%, and 80% isodose line in one patient each. Nine tumors (26%) were smaller, and 26 tumors (74%) were unchanged. No tumor had progressed. The 1- and 2-year actuarial incidences of facial neuropathy were 52.2% and 66.5%, respectively. The 1- and 2-year actuarial incidences of trigeminal neuropathy were 33.7% and 58.9%, respectively. The 1- and 2-year actuarial incidence of facial or trigeminal neuropathy (or both) was 60.8% and 81.7%, respectively. Multivariate analysis revealed that the following were associated with the time of onset or worsening of facial weakness or trigeminal neuropathy: (a) patients < age 65 years, (b) dose to the tumor margin, (c) maximum tumor diameter {>=} 21 mm, (d) use of the 18 mm collimator, and (e) use of > five isocenters. The 1- and 2-year actuarial rates of preservation of useful hearing (Gardner-Robertson class I or II) were 100% and 41.7% {plus_minus} 17.3, respectively. Stereotactic radiosurgery using the gamma knife provides short-term control of acoustic neuromas when a dose of 16 to 20 Gy to the tumor margin is used. Preservation of useful hearing can be accomplished in a significant proportion of patients. 30 refs., 5 tabs.

  1. A modular Geant4 model of Leksell Gamma Knife Perfexion™

    NASA Astrophysics Data System (ADS)

    Pipek, J.; Novotný, J.; Novotný, J., Jr.; Kozubíková, P.

    2014-12-01

    This work presents a Monte Carlo model of Leksell Gamma Knife Perfexion as well as the main parameters of the dose distribution in the standard phantom obtained using this model. The model is developed in the Geant4 simulation toolkit in a modular way which enables its reuse in other Perfexion studies. Large phase space files were created, containing particles that are entering the inner machine cavity after being transported through the collimation system. All 14 output factors of the machine and effective output factors for both the 4 mm (0.830 ± 0.009) and 8 mm (0.921 ± 0.004) collimators were calculated. Dose profiles along the main axes are also included for each collimator size. All results are compared to the values obtained from the treatment planning system, from experiments, and from other Monte Carlo models.

  2. Gamma knife radiosurgery for medically refractory idiopathic trigeminal neuralgia.

    PubMed

    Kang, J H; Yoon, Y S; Kang, D W; Chung, S S; Chang, J W

    2008-01-01

    Gamma knife radiosurgery (GKS) has been generally considered as a viable therapeutic option for the management of medically refractory idiopathic trigeminal neuralgia (TN). We reviewed our experience with GKS in patients with TN. Between Feb 1996 and May 2006, 77 patients with medical refractory idiopathic TN were treated using GKS. Thirty-six patients who had undergone other previous procedures, previous GKS, or had brain stem lesion, atypical symptoms, were excluded from this study. Pain improvement was achieved in 38 of the patients with TN (pain response rate 92.7%). Twenty-three patients were pain free and 15 had reduced pain. There were no serious complications. We think that GKS is an effective treatment option for patients with medical refractory idiopathic TN. PMID:18642631

  3. A modular Geant4 model of Leksell Gamma Knife Perfexion™.

    PubMed

    Pipek, J; Novotný, J; Novotný, J; Kozubíková, P

    2014-12-21

    This work presents a Monte Carlo model of Leksell Gamma Knife Perfexion as well as the main parameters of the dose distribution in the standard phantom obtained using this model. The model is developed in the Geant4 simulation toolkit in a modular way which enables its reuse in other Perfexion studies. Large phase space files were created, containing particles that are entering the inner machine cavity after being transported through the collimation system. All 14 output factors of the machine and effective output factors for both the 4 mm (0.830 ± 0.009) and 8 mm (0.921 ± 0.004) collimators were calculated. Dose profiles along the main axes are also included for each collimator size. All results are compared to the values obtained from the treatment planning system, from experiments, and from other Monte Carlo models. PMID:25415510

  4. SU-E-T-542: Comparison of Stereotactic Radiosurgery (SRS) of Brain Lesions Using Gamma Knife, VMAT, IMRT, and Conformal Arcs

    SciTech Connect

    Li, S; Charpentier, P; Chan, P; Neicu, T; Miyamoto, C

    2014-06-01

    Purpose: To compare dose distributions in stereotactic radiation surgery of brain lesions using gamma Knife, VMAT, conformal arcs, and IMRT in order to provide an optimal treatment. Methods: Dose distributions from single shot of 4C model of Gamma Knife at the helmet collimation sizes of 4, 8, 14, and 18 mm in diameter were compared with full arcs with the square shapes of 4×4 (or 5×5), 8×8 (or 10×10), and spherical shapes of 16 or 20 mm in diameter using EDR3 films in the same gamma knife QA phantom. Plans for ten SRS cases with single and multiple lesions were created in gamma knife plans and Pinnacle plans. The external beam plans had enlarged field size by 2-mm and used single conformal full circle arc for solitary lesion and none coplanar arcs/beams for multiple lesions. Coverage, conformity index, dose to critical organs, and integral dose to the brain and nearby critical structures were compared on all plans. Structures and dose matrices were registered in a Velocity deformable image registration system. Results: Single full circle arc from Elekta beam-modulate MLC (4-mm leaf thickness) and agility MLC (5-mm leaf thickness) have larger penumbra and less flatness than that of Gamma Knife single shot. None-coplanar arcs or beams were required to achieve similar dose distribution. In general, Gamma Knife plans provided significant less integral dose than that of linac-based plans. Benefits of IMRT and VMAT versus gamma Knife and conformal arcs were not significant. Conclusion: Our dose measurement and treatment planning evaluation clearly demonstrated dose distribution differences amount current popular SRS modalities for small solitary and multiple brain lesions. The trend of using MLC shape beams or arcs to replace conventional cones should be revisited in order to keep lower integral dose if the late correlates with some radiation-induced side effects. Pilot grant from Elekta LLC.

  5. Gamma Knife surgical treatment for partially embolized cerebral arteriovenous malformations.

    PubMed

    Huo, Xiaochuan; Jiang, Yuhua; Lv, Xianli; Yang, Hongchao; Zhao, Yang; Li, Youxiang

    2016-03-01

    OBJECT A combination of embolization and radiosurgery is used as a common strategy for the treatment of large and complex cerebral arteriovenous malformations (AVMs). This study presents the experiences of partially embolized cerebral AVMs followed by Gamma Knife surgery (GKS) and assesses predictive factors for AVM obliteration and hemorrhage. METHODS The interventional neuroradiology database that was reviewed included 404 patients who underwent AVM embolization. Using this database, the authors retrospectively analyzed all partially embolized AVM cases followed by GKS for a residual nidus. Except for cases of complete AVM obliteration, the authors excluded all patients with radiological follow-up of less than 2 years. Logistic regression analysis was used to analyze the predictive factors related to AVM obliteration and hemorrhage following GKS. Kaplan-Meier analysis was used to evaluate the obliteration with a cutoff AVM nidus volume of 3 cm(3) and 10 cm(3). RESULTS One hundred sixty-two patients qualified for the study. The median patient age was 26 years and 48.8% were female. Hemorrhage presented as the most common symptom (48.1%). The median preembolization volume of an AVM was 14.3 cm(3). The median volume and margin dose for GKS were 10.92 cm(3) and 16.0 Gy, respectively. The median radiological and clinical follow-up intervals were 47 and 79 months, respectively. The annual hemorrhage rate was 1.71% and total obliteration rate was 56.8%. Noneloquent area (p = 0.004), superficial location (p < 0.001), decreased volume (p < 0.001), lower Spetzler-Martin grade (p < 0.001), lower Virginia Radiosurgery AVM Scale (RAS; p < 0.001), lower Pollock-Flickinger score (p < 0.001), lower modified Pollock-Flickinger score (p < 0.001), increased maximum dose (p < 0.001), and increased margin dose (p < 0.001) were found to be statistically significant in predicting the probability of AVM obliteration in the univariate analysis. In the multivariate analysis, only volume

  6. Gamma Knife radiosurgery with CT image-based dose calculation.

    PubMed

    Xu, Andy Yuanguang; Bhatnagar, Jagdish; Bednarz, Greg; Niranjan, Ajay; Kondziolka, Douglas; Flickinger, John; Lunsford, L Dade; Huq, M Saiful

    2015-01-01

    The Leksell GammaPlan software version 10 introduces a CT image-based segmentation tool for automatic skull definition and a convolution dose calculation algorithm for tissue inhomogeneity correction. The purpose of this work was to evaluate the impact of these new approaches on routine clinical Gamma Knife treatment planning. Sixty-five patients who underwent CT image-guided Gamma Knife radiosurgeries at the University of Pittsburgh Medical Center in recent years were retrospectively investigated. The diagnoses for these cases include trigeminal neuralgia, meningioma, acoustic neuroma, AVM, glioma, and benign and metastatic brain tumors. Dose calculations were performed for each patient with the same dose prescriptions and the same shot arrangements using three different approaches: 1) TMR 10 dose calculation with imaging skull definition; 2) convolution dose calculation with imaging skull definition; 3) TMR 10 dose calculation with conventional measurement-based skull definition. For each treatment matrix, the total treatment time, the target coverage index, the selectivity index, the gradient index, and a set of dose statistics parameters were compared between the three calculations. The dose statistics parameters investigated include the prescription isodose volume, the 12 Gy isodose volume, the minimum, maximum and mean doses on the treatment targets, and the critical structures under consideration. The difference between the convolution and the TMR 10 dose calculations for the 104 treatment matrices were found to vary with the patient anatomy, location of the treatment shots, and the tissue inhomogeneities around the treatment target. An average difference of 8.4% was observed for the total treatment times between the convolution and the TMR algorithms. The maximum differences in the treatment times, the prescription isodose volumes, the 12 Gy isodose volumes, the target coverage indices, the selectivity indices, and the gradient indices from the convolution

  7. Air kerma based dosimetry calibration for the Leksell Gamma Knife

    SciTech Connect

    Meltsner, Sheridan Griffin; DeWerd, Larry A.

    2009-02-15

    No accepted official protocol exists for the dosimetry of the Leksell Gamma Knife registered (GK) stereotactic radiosurgery device. Establishment of a dosimetry protocol has been complicated by the unique partial-hemisphere arrangement of 201 individual {sup 60}Co beams simultaneously focused on the treatment volume and by the rigid geometry of the GK unit itself. This article proposes an air kerma based dosimetry protocol using either an in-air or in-acrylic phantom measurement to determine the absorbed dose rate of fields of the 18 mm helmet of a GK unit. A small-volume air ionization chamber was used to make measurements at the physical isocenter of three GK units. The absorbed dose rate to water was determined using a modified version of the AAPM Task Group 21 protocol designed for use with {sup 60}Co-based teletherapy machines. This experimentally determined absorbed dose rate was compared to the treatment planning system (TPS) absorbed dose rate. The TPS used with the GK unit is Leksell GammaPlan. The TPS absorbed dose rate at the time of treatment is the absorbed dose rate determined by the physicist at the time of machine commissioning decay corrected to the treatment date. The TPS absorbed dose rate is defined as absorbed dose rate to water at the isocenter of a water phantom with a radius of 8 cm. Measurements were performed on model B and C Gamma Knife units. The absorbed dose rate to water for the 18 mm helmet determined using air-kerma based calculations is consistently between 1.5% and 2.9% higher than the absorbed dose rate provided by the TPS. These air kerma based measurements allow GK dosimetry to be performed with an established dosimetry protocol and without complications arising from the use of and possible variations in solid phantom material. Measurements were also made with the same ionization chamber in a spherical acrylic phantom for comparison. This methodology will allow further development of calibration methods appropriate for the

  8. Gamma Knife radiosurgery for the treatment of cavernous sinus hemangiomas

    PubMed Central

    XU, QINGSHENG; SHEN, JIAN; FENG, YIPING; ZHAN, RENYA

    2016-01-01

    The present retrospective study aimed to analyze the outcome of patients with cavernous sinus hemangioma (CSH) treated with Gamma Knife radiosurgery (GKS). Between August 2011 and April 2014, 7 patients with CSHs underwent GKS. GKS was performed as the sole treatment option in 5 patients, whilst partial resection had been performed previously in 1 patient and biopsy had been performed in 1 patient. The mean volume of the tumors at the time of GKS was 12.5±10.2 cm3 (range, 5.3–33.2 cm3), and the median prescription of peripheral dose was 14.0 Gy (range, 10.0–15.0 Gy). The mean follow-up period was 20 months (range, 6–40 months). At the last follow-up, the lesion volume had decreased in all patients, and all cranial neuropathies observed prior to GKS had improved. There were no radiation-induced neuropathies or complications during the follow-up period. GKS appears to be an effective and safe treatment modality for the management of CSHs. PMID:26893777

  9. Measurement of Gamma Knife registered helmet factors using MOSFETs

    SciTech Connect

    Kurjewicz, Laryssa; Berndt, Anita

    2007-03-15

    The relative dose rate for the different Gamma Knife registered helmets (4, 8, 14, and 18 mm) is characterized by their respective helmet factors. Since the plateau of the dose profile for the 4 mm helmet is at most 1 mm wide, detector choices are limited. Traditionally helmet factors have been measured using 1x1x1 mm{sup 3} thermoluminescent dosimeters (TLDs). However, these are time-consuming, cumbersome measurements. This article investigates the use of metal-oxide-semiconductor field effect transistors (MOSFETs) (active area of 0.2x0.2 mm{sup 2}) as a more accurate and convenient dosimeter. Their suitability for these measurements was confirmed by basic characterization measurements. Helmet factors were measured using both MOSFETs and the established TLD approach. A custom MOSFET cassette was designed in analogy to the Elekta TLD cassette (Elekta Instruments AB) for use with the Elekta dosimetry sphere. Although both dosimeters provided values within 3% of the manufacturer's suggestion, MOSFETs provided superior accuracy and precision, in a fraction of the time required for the TLD measurements. Thus, MOSFETs proved to be a reasonable alternative to TLDs for performing helmet factor measurements.

  10. Shielding requirements on-site loading and acceptance testing on the Leksell gamma knife.

    PubMed

    Maitz, A H; Lunsford, L D; Wu, A; Lindner, G; Flickinger, J C

    1990-02-01

    On August 14, 1987, the first stereotactic radiosurgical procedure using the gamma knife was performed in North America. Located in a self-contained radiosurgical suite in the basement of Presbyterian-University Hospital in Pittsburgh, Pennsylvania. This device uses 201 highly focused beams 60Co for the single-treatment closed-skull irradiation of brain lesions localized by stereotactic techniques (radiosurgery). One hundred and fifty-two patients with intracranial arteriovenous malformations or brain tumors were treated in the first year of operation. The Presbyterian University Hospital of Pittsburgh gamma knife is the first such unit in which the 60Co sources were loaded on-site. This effort required us to solve some difficult and unusual problems encountered during site preparation, delivery, and loading of the unit in a busy hospital setting. The solutions developed enabled installation and use of the gamma knife with minimal disruption of hospital activities while maintaining acceptable levels of exposure to radiation. Environmental surveys performed during the loading of the 201 radioactive sources (total, 219 TBq) confirmed that on-site loading is possible and practical. Our experience in the design, construction, and implementation of the first North American gamma knife supports the practicality and safety of on-site loading and may be of value in the planning and development of future gamma knife installations. PMID:2406231

  11. Leksell Gamma Knife treatment for pilocytic astrocytomas: long-term results.

    PubMed

    Simonova, Gabriela; Kozubikova, Petra; Liscak, Roman; Novotny, Josef

    2016-07-01

    OBJECTIVE The purpose of this study was to evaluate long-term treatment results, radiation-related toxicity, and prognostic factors for the progression-free survival (PFS) of patients with pilocytic astrocytomas treated by means of stereotactic radiosurgery with a Leksell Gamma Knife. METHODS A total of 25 patients with pilocytic astrocytomas underwent Gamma Knife surgery during the period 1992-2002. The median target volume was 2700 mm(3) (range 205-25,000 mm(3)). The 18 patients treated with 5 daily fractions received a median minimum target dose of 25 Gy. Doses for the 2 patients treated with 10 fractions over 5 days (2 fractions delivered on the same day at least 6 hours apart) were 23 and 28 Gy. For the 5 patients treated with a single fraction, the minimum target dose ranged from 13 to 20 Gy (median 16 Gy). RESULTS Complete regression occurred in 10 patients (40%) and partial regression in 10 patients (40%). The 10-year overall survival rate was 96% and the 10-year PFS rate was 80%. Target volume appeared to be a significant prognostic factor for PFS (p = 0.037). Temporary Grade 3 toxicity appeared in 2 patients (8%), and these patients were treated with corticosteroids for 2 months. Permanent Grade 4 toxicity appeared in 2 patients (8%) and was associated with neurocognitive dysfunction. In these 2 individuals, the neurocognitive dysfunction was also felt to be in part the result of the additional therapeutic interventions (4 in one case and 6 in the other) required to achieve durable control of their tumors. CONCLUSIONS Radiosurgery represents an alternative treatment modality for small residual or recurrent volumes of pilocytic astrocytomas and provides long-term local control. Target volume appears to be the most important factor affecting PFS. PMID:26991883

  12. Adaptive hypofractionated gamma knife radiosurgery for a large brainstem metastasis

    PubMed Central

    Sinclair, Georges; Bartek, Jiri; Martin, Heather; Barsoum, Pierre; Dodoo, Ernest

    2016-01-01

    Background: To demonstrate how adaptive hypofractionated radiosurgery by gamma knife (GK) can be successfully utilized to treat a large brainstem metastasis - a novel approach to a challenging clinical situation. Case Description: A 42-year-old woman, diagnosed with metastatic nonsmall cell lung cancer in July 2011, initially treated with chemotherapy and tyrosine kinase inhibitors, developed multiple brain metastases March 2013, with subsequent whole brain radiotherapy, after which a magnetic resonance imaging (MRI) showed a significant volume regression of all brain metastases. A follow-up MRI in October 2013 revealed a growing brainstem lesion of 26 mm. Linear accelerator-based radiotherapy and microsurgery were judged contraindicated, why the decision was made to treat the patient with three separate radiosurgical sessions during the course of 1 week, with an 18% tumor volume reduction demonstrated after the last treatment. Follow-up MRI 2.5 months after her radiosurgical treatment showed a tumor volume reduction of 67% compared to the 1st day of treatment. Later on, the patient developed a radiation-induced perilesional edema although without major clinical implications. An MRI at 12 months and 18-fluoro-deoxyglucose positron emission tomography of the brain at 13 months showed decreased edema with no signs of tumor recurrence. Despite disease progression during the last months of her life, the patient's condition remained overall acceptable. Conclusion: GK-based stereotactic adaptive hypofractionation proved to be effective to achieve tumor control while limiting local adverse reactions. This surgical modality should be considered when managing larger brain lesions in critical areas. PMID:26958430

  13. Salvage Gamma Knife Stereotactic Radiosurgery for Surgically Refractory Trigeminal Neuralgia

    SciTech Connect

    Little, Andrew S.; Shetter, Andrew G. Shetter, Mary E.; Kakarla, Udaya K.; Rogers, C. Leland

    2009-06-01

    Purpose: To evaluate the clinical outcome of patients with surgically refractory trigeminal neuralgia (TN) treated with rescue gamma knife radiosurgery (GKRS). Methods and Materials: Seventy-nine patients with typical TN received salvage GKRS between 1997 and 2002 at the Barrow Neurological Institute (BNI). All patients had recurrent pain following at least one prior surgical intervention. Prior surgical interventions included percutaneous destructive procedures, microvascular decompression (MVD), or GKRS. Thirty-one (39%) had undergone at least two prior procedures. The most common salvage dose was 80 Gy, although 40-50 Gy was typical in patients who had received prior radiosurgery. Pain outcome was assessed using the BNI Pain Intensity Score, and quality of life was assessed using the Brief Pain Inventory. Results: Median follow-up after salvage GKRS was 5.3 years. Actuarial analysis demonstrated that at 5 years, 20% of patients were pain-free and 50% had pain relief. Pain recurred in patients who had an initial response to GKRS at a median of 1.1 years. Twenty-eight (41%) required a subsequent surgical procedure for recurrence. A multivariate Cox proportional hazards model suggested that the strongest predictor of GKRS failure was a history of prior MVD (p=0.029). There were no instances of serious morbidity or mortality. Ten percent of patients developed worsening facial numbness and 8% described their numbness as 'very bothersome.' Conclusions: GKRS salvage for refractory TN is well tolerated and results in long-term pain relief in approximately half the patients treated. Clinicians may reconsider using GKRS to salvage patients who have failed prior MVD.

  14. Gamma Knife Radiosurgery for the Treatment of Cystic Cerebral Metastases

    SciTech Connect

    Ebinu, Julius O.; Lwu, Shelly; Monsalves, Eric; Arayee, Mandana; Chung, Caroline; Laperriere, Normand J.; Kulkarni, Abhaya V.; Goetz, Pablo; Zadeh, Gelareh

    2013-03-01

    Purpose: To assess the role of Gamma Knife radiosurgery (GKRS) in the treatment of nonsurgical cystic brain metastasis, and to determine predictors of response to GKRS. Methods: We reviewed a prospectively maintained database of brain metastases patients treated at our institution between 2006 and 2010. All lesions with a cystic component were identified, and volumetric analysis was done to measure percentage of cystic volume on day of treatment and consecutive follow-up MRI scans. Clinical, radiologic, and dosimetry parameters were reviewed to establish the overall response of cystic metastases to GKRS as well as identify potential predictive factors of response. Results: A total of 111 lesions in 73 patients were analyzed; 57% of lesions received prior whole-brain radiation therapy (WBRT). Lung carcinoma was the primary cancer in 51% of patients, 10% breast, 10% colorectal, 4% melanoma, and 26% other. Fifty-seven percent of the patients were recursive partitioning analysis class 1, the remainder class 2. Mean target volume was 3.3 mL (range, 0.1-23 mL). Median prescription dose was 21 Gy (range, 15-24 Gy). Local control rates were 91%, 63%, and 37% at 6, 12, and 18 months, respectively. Local control was improved in lung primary and worse in patients with prior WBRT (univariate). Only lung primary predicted local control in multivariate analysis, whereas age and tumor volume did not. Lesions with a large cystic component did not show a poorer response compared with those with a small cystic component. Conclusions: This study supports the use of GKRS in the management of nonsurgical cystic metastases, despite a traditionally perceived poorer response. Our local control rates are comparable to a matched cohort of noncystic brain metastases, and therefore the presence of a large cystic component should not deter the use of GKRS. Predictors of response included tumor subtype. Prior WBRT decreased effectiveness of SRS for local control rates.

  15. Clinical outcomes following salvage Gamma Knife radiosurgery for recurrent glioblastoma

    PubMed Central

    Larson, Erik W; Peterson, Halloran E; Lamoreaux, Wayne T; MacKay, Alexander R; Fairbanks, Robert K; Call, Jason A; Carlson, Jonathan D; Ling, Benjamin C; Demakas, John J; Cooke, Barton S; Lee, Christopher M

    2014-01-01

    Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor with a survival prognosis of 14-16 mo for the highest functioning patients. Despite aggressive, multimodal upfront therapies, the majority of GBMs will recur in approximately six months. Salvage therapy options for recurrent GBM (rGBM) are an area of intense research. This study compares recent survival and quality of life outcomes following Gamma Knife radiosurgery (GKRS) salvage therapy. Following a PubMed search for studies using GKRS as salvage therapy for malignant gliomas, nine articles from 2005 to July 2013 were identified which evaluated rGBM treatment. In this review, we compare Overall survival following diagnosis, Overall survival following salvage treatment, Progression-free survival, Time to recurrence, Local tumor control, and adverse radiation effects. This report discusses results for rGBM patient populations alone, not for mixed populations with other tumor histology grades. All nine studies reported median overall survival rates (from diagnosis, range: 16.7-33.2 mo; from salvage, range: 9-17.9 mo). Three studies identified median progression-free survival (range: 4.6-14.9 mo). Two showed median time to recurrence of GBM. Two discussed local tumor control. Six studies reported adverse radiation effects (range: 0%-46% of patients). The greatest survival advantages were seen in patients who received GKRS salvage along with other treatments, like resection or bevacizumab, suggesting that appropriately tailored multimodal therapy should be considered with each rGBM patient. However, there needs to be a randomized clinical trial to test GKRS for rGBM before the possibility of selection bias can be dismissed. PMID:24829861

  16. Neuropsychological outcomes after Gamma Knife radiosurgery for mesial temporal lobe epilepsy: a prospective multicenter study

    PubMed Central

    Quigg, Mark; Broshek, Donna K.; Barbaro, Nicholas M.; Ward, Mariann M.; Laxer, Kenneth D.; Yan, Guofen; Lamborn, Kathleen

    2012-01-01

    Purpose To assess outcomes of language, verbal memory, cognitive efficiency and mental flexibility, mood, and quality of life (QOL) in a prospective, multicenter pilot study of Gamma Knife radiosurgery (RS) for mesial temporal lobe epilepsy (MTLE). Methods RS, randomized to 20 Gy or 24 Gy comprising 5.5-7.5mL at the 50% isodose volume, was performed on mesial temporal structures of patients with unilateral MTLE. Neuropsychological evaluations were performed at preoperative baseline, and mean change scores were described at 12 and 24 months postoperatively. QOL data were also available at 36 months. Key Findings 30 patients were treated and 26 were available for the final 24 month neuropsychological evaluation. Neither language (Boston Naming Test), verbal memory (California Verbal Learning Test and Logical Memory subtest of the Wechsler Memory Scale-Revised), cognitive efficiency and mental flexibility (Trail Making Test), nor mood (Beck Depression Inventory) differed from baseline. QOL scores improved at 24 and 36 months, with those patients attaining seizure remission by month 24 accounting for the majority of the improvement. Significance The serial changes in cognitive outcomes, mood, and QOL are unremarkable following RS for MTLE. RS may provide an alternative to open surgery especially in those patients at risk of cognitive impairment or who desire a noninvasive alternative to open surgery. PMID:21426323

  17. Two-year experience with the commercial Gamma Knife Check software.

    PubMed

    Xu, Andy Yuanguang; Bhatnagar, Jagdish; Bednarz, Greg; Novotny, Josef; Flickinger, John; Lunsford, L Dade; Huq, M Saiful

    2016-01-01

    The Gamma Knife Check software is an FDA approved second check system for dose calculations in Gamma Knife radiosurgery. The purpose of this study was to evaluate the accuracy and the stability of the commercial software package as a tool for independent dose verification. The Gamma Knife Check software version 8.4 was commissioned for a Leksell Gamma Knife Perfexion and a 4C unit at the University of Pittsburgh Medical Center in May 2012. Independent dose verifications were performed using this software for 319 radiosurgery cases on the Perfexion and 283 radiosurgery cases on the 4C units. The cases on each machine were divided into groups according to their diagnoses, and an averaged absolute percent dose difference for each group was calculated. The percentage dose difference for each treatment target was obtained as the relative difference between the Gamma Knife Check dose and the dose from the tissue maximum ratio algorithm (TMR 10) from the GammaPlan software version 10 at the reference point. For treatment plans with imaging skull definition, results obtained from the Gamma Knife Check software using the measurement-based skull definition method are used for comparison. The collected dose difference data were also analyzed in terms of the distance from the treatment target to the skull, the number of treatment shots used for the target, and the gamma angles of the treatment shots. The averaged percent dose differences between the Gamma Knife Check software and the GammaPlan treatment planning system are 0.3%, 0.89%, 1.24%, 1.09%, 0.83%, 0.55%, 0.33%, and 1.49% for the trigeminal neuralgia, acoustic neuroma, arteriovenous malformation (AVM), meningioma, pituitary adenoma, glioma, functional disorders, and metastasis cases on the Perfexion unit. The corresponding averaged percent dose differences for the 4C unit are 0.33%, 1.2%, 2.78% 1.99%, 1.4%, 1.92%, 0.62%, and 1.51%, respectively. The dose difference is, in general, larger for treatment targets in the

  18. Dose De-Escalation With Gamma Knife Radiosurgery in the Treatment of Choroidal Melanoma

    SciTech Connect

    Schirmer, Clemens M.; Chan, Michael; Mignano, John; Duker, Jay; Melhus, Christopher S.; Williams, Lloyd B.; Wu, Julian K.; Yao, Kevin C.

    2009-09-01

    Purpose: Single-fraction targeted radiation therapy delivered by the Leksell Gamma Knife system is a minimally invasive treatment option for choroidal melanoma that has been used as an alternative to enucleation, proton beam therapy, or brachytherapy. Previously reported Gamma Knife series involved the treatment of choroidal melanomas with a dose of 40 to 50 Gy at the tumor margin. We report our institutional experience using a significantly lower dose. Methods and Materials: Fourteen patients with choroidal melanoma were treated with the Leksell Gamma Knife at our institution over a 7-year period. The treatment and clinical data were analyzed in a retrospective fashion after a mean follow-up of 32.2 months. Results: The mean dose to the tumor margin was 22.2 {+-} 2.4 Gy (range, 20- 25 Gy). Mean treated tumor volume was 1.1 {+-} 1.2 cc. Local control was achieved in 13 cases (93%). In 1 patient both intraocular spread and distant metastatic disease developed after treatment. Visual function of the affected eye was preserved in 5 patients (36%) at latest follow-up, in 9 patients (64%) visual loss ensued. Mild to moderate radiation toxicity developed in 8 patients. Conclusions: Choroidal melanoma can be safely and effectively treated using Leksell Gamma Knife stereotactic radiosurgery with a marginal dose of less than 25 Gy.

  19. Gentlemen (and ladies), choose your weapons: Gamma knife vs. linear accelerator radiosurgery.

    PubMed

    Stieber, Volker W; Bourland, J Daniel; Tome, Wolfgang A; Mehta, Minesh P

    2003-04-01

    This article compares and contrasts Gamma Knife radiosurgery with linear accelerator-based radiosurgery; where appropriate, Cyberknife technology is discussed. Topics covered are: positioning of the head (invasive versus non-invasive positioning systems); collimator construction; beam properties; beam arrangements; treatment planning; and issues regarding manpower (including a discussion of patient repositioning during treatment), machine availability, and financial considerations. PMID:12680787

  20. Whole-procedure clinical accuracy of Gamma Knife treatments of large lesions

    SciTech Connect

    Ma Lijun; Chuang, Cynthia; Descovich, Martina; Petti, Paula; Smith, Vernon; Verhey, Lynn

    2008-11-15

    The mechanical accuracy of Gamma Knife radiosurgery based on single-isocenter measurement has been established to within 0.3 mm. However, the full delivery accuracy for Gamma Knife treatments of large lesions has only been estimated via the quadrature-sum analysis. In this study, the authors directly measured the whole-procedure accuracy for Gamma Knife treatments of large lesions to examine the validity of such estimation. The measurements were conducted on a head-phantom simulating the whole treatment procedure that included frame placement, computed tomography imaging, treatment planning, and treatment delivery. The results of the measurements were compared with the dose calculations from the treatment planning system. Average agreements of 0.1-1.6 mm for the isodose lines ranging from 25% to 90% of the maximum dose were found despite potentially large contributing uncertainties such as 3-mm imaging resolution, 2-mm dose grid size, 1-mm frame registration, multi-isocenter deliveries, etc. The results of our measurements were found to be significantly smaller (>50%) than the calculated value based on the quadrature-sum analysis. In conclusion, Gamma Knife treatments of large lesions can be delivered much more accurately than predicted from the quadrature-sum analysis of major sources of uncertainties from each step of the delivery chain.

  1. Comparative analyses of linac and Gamma Knife radiosurgery for trigeminal neuralgia treatments

    NASA Astrophysics Data System (ADS)

    Ma, L.; Kwok, Y.; Chin, L. S.; Yu, C.; Regine, W. F.

    2005-11-01

    Dedicated linac-based radiosurgery has been reported for trigeminal neuralgia treatments. In this study, we investigated the dose fall-off characteristics and setup error tolerance of linac-based radiosurgery as compared with standard Gamma Knife radiosurgery. In order to minimize the errors from different treatment planning calculations, consistent imaging registration, dose calculation and dose volume analysis methods were developed and implemented for both Gamma Knife and linac-based treatments. Intra-arc setup errors were incorporated into the treatment planning process of linac-based deliveries. The effects of intra-arc setup errors with increasing number of arcs were studied and benchmarked against Gamma Knife deliveries with and without plugging patterns. Our studies found equivalent dose fall-off properties between Gamma Knife and linac-based radiosurgery given a sufficient number of arcs (>7) and small intra-arc errors (<0.5 mm) were satisfied for linac-based deliveries. Increasing the number of arcs significantly decreased the variations in the dose fall-off curve at the low isodose region (e.g. from 40% to 10%) and also improved dose uniformity at the high isodose region (e.g. from 70% to 90%). As the number of arcs increased, the effects of intra-arc setup errors on the dose fall-off curves decreased. Increasing the number of arcs also reduced the integral dose to the distal normal brain tissues. In conclusion, linac-based radiosurgery produces equivalent dose fall-off characteristics to Gamma Knife radiosurgery with a high number of arcs. However, one must note the increased treatment time for a large number of arcs and isocentre accuracies.

  2. Outcome of Gamma Knife Thalamotomy in Patients with an Intractable Tremor

    PubMed Central

    Cho, Kyung Rae; Kim, Hong Rye; Im, Yong Seok; Youn, Jinyoung; Cho, Jin Whan

    2015-01-01

    Objective Tremor is a common movement disorder that interferes with daily living. Since the medication for tremor has some limitations, surgical intervention is needed in many patients. In certain patients who cannot undergo aggressive surgical intervention, Gamma Knife thalamotomy (GKT) is a safe and effective alternative. Methods From June 2012 to August 2013, 7 patients with an intractable tremor underwent GKT. Four of these 7 patients had medical comorbidities, and 3 patients refused to undergo traditional surgery. Each patient was evaluated with the modified Fahn-Tolosa-Marin tremor rating scale (TRS) along with analysis of handwriting samples. All of the patients underwent GKT with a maximal dose of 130 Gy to the left ventralis intermedius (VIM) nucleus of the thalamus. Follow-up brain MRI was performed after 3 to 8 months of GKT, and evaluation with the TRS was also performed. Results Six patients showed objective improvement in the TRS score. Excluding one patient who demonstrated tremor progression, there was 28.9% improvement in the TRS score. However, five patients showed subjective improvement in their symptoms. On comparing the TRS scores between follow-up periods of more and less than 4 months, the follow-up TRS score at more than 4 months of GKT was significantly improved compared to that at less than 4 months of GKT. Follow-up MRI showed radiosurgical changes in 5 patients. Conclusion GKT with a maximal dose of 130 Gy to the VIM is a safe procedure that can replace other surgical procedures. PMID:25810859

  3. Selective source blocking for Gamma Knife radiosurgery of trigeminal neuralgia based on analytical dose modelling.

    PubMed

    Li, Kaile; Ma, Lijun

    2004-08-01

    We have developed an automatic critical region shielding (ACRS) algorithm for Gamma Knife radiosurgery of trigeminal neuralgia. The algorithm selectively blocks 201 Gamma Knife sources to minimize the dose to the brainstem while irradiating the root entry area of the trigeminal nerve with 70-90 Gy. An independent dose model was developed to implement the algorithm. The accuracy of the dose model was tested and validated via comparison with the Leksell GammaPlan (LGP) calculations. Agreements of 3% or 3 mm in isodose distributions were found for both single-shot and multiple-shot treatment plans. After the optimized blocking patterns are obtained via the independent dose model, they are imported into the LGP for final dose calculations and treatment planning analyses. We found that the use of a moderate number of source plugs (30-50 plugs) significantly lowered (approximately 40%) the dose to the brainstem for trigeminal neuralgia treatments. Considering the small effort involved in using these plugs, we recommend source blocking for all trigeminal neuralgia treatments with Gamma Knife radiosurgery. PMID:15379025

  4. An investigation of eye lens dose for gamma knife treatments of trigeminal neuralgia.

    PubMed

    Ma, L; Chin, L; Sarfaraz, M; Shepard, D; Yu, C

    2000-01-01

    Stereotactic Gamma Knife radiosurgery has been widely used for treating trigeminal neuralgia (TN). A single large fractional dose of 7000 to 9000 cGy is commonly prescribed as the maximum dose for these treatments. For this reason, if a small percentage of the prescribed dose such as 2-3% scattered to the eye, it could reach or even exceed the tolerance dose of the lens. For several TN cases, we found that the Leksell Gamma Plan system calculates the lens dose about 0.5-2% of the maximum dose independent of the use of eye shielding. These dose values are significantly high and it motivated us to investigate the lens dose for the TN patients treated with stereotactic Gamma Knife radiosurgery. Phantom studies and in vivo dosimetry measurements were carried out for six patients treated at our institution. The average dose to the lens ipsilateral to the treated nerve was measured to be 7.7+/-0.6 cGy. Based on the biological model of Lyman and Emami [Int. J. Radiat. Oncol. Biol. Phys. 21, 109-122 (1991)], the probability of the lens complication (cataract) was determined to be 0.1%. Our findings suggest that few TN patients would develop cataracts after receiving Gamma Knife radiosurgery. PMID:11674826

  5. A simple method of independent treatment time verification in gamma knife radiosurgery using integral dose

    SciTech Connect

    Jin Jianyue; Drzymala, Robert; Li Zuofeng

    2004-12-01

    The purpose of this study is to develop a simple independent dose calculation method to verify treatment plans for Leksell Gamma Knife radiosurgery. Our approach uses the total integral dose within the skull as an end point for comparison. The total integral dose is computed using a spreadsheet and is compared to that obtained from Leksell GammaPlan registered . It is calculated as the sum of the integral doses of 201 beams, each passing through a cylindrical volume. The average length of the cylinders is estimated from the Skull-Scaler measurement data taken before treatment. Correction factors are applied to the length of the cylinder depending on the location of a shot in the skull. The radius of the cylinder corresponds to the collimator aperture of the helmet, with a correction factor for the beam penumbra and scattering. We have tested our simple spreadsheet program using treatment plans of 40 patients treated with Gamma Knife registered in our center. These patients differ in geometry, size, lesion locations, collimator helmet, and treatment complexities. Results show that differences between our calculations and treatment planning results are typically within {+-}3%, with a maximum difference of {+-}3.8%. We demonstrate that our spreadsheet program is a convenient and effective independent method to verify treatment planning irradiation times prior to implementation of Gamma Knife radiosurgery.

  6. Selective source blocking for Gamma Knife radiosurgery of trigeminal neuralgia based on analytical dose modelling

    NASA Astrophysics Data System (ADS)

    Li, Kaile; Ma, Lijun

    2004-08-01

    We have developed an automatic critical region shielding (ACRS) algorithm for Gamma Knife radiosurgery of trigeminal neuralgia. The algorithm selectively blocks 201 Gamma Knife sources to minimize the dose to the brainstem while irradiating the root entry area of the trigeminal nerve with 70-90 Gy. An independent dose model was developed to implement the algorithm. The accuracy of the dose model was tested and validated via comparison with the Leksell GammaPlan (LGP) calculations. Agreements of 3% or 3 mm in isodose distributions were found for both single-shot and multiple-shot treatment plans. After the optimized blocking patterns are obtained via the independent dose model, they are imported into the LGP for final dose calculations and treatment planning analyses. We found that the use of a moderate number of source plugs (30-50 plugs) significantly lowered (~40%) the dose to the brainstem for trigeminal neuralgia treatments. Considering the small effort involved in using these plugs, we recommend source blocking for all trigeminal neuralgia treatments with Gamma Knife radiosurgery.

  7. A technique to sharpen the beam penumbra for Gamma Knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Guerrero, M.; Li, X. Allen; Ma, Lijun

    2003-06-01

    In stereotactic radiosurgery, a narrow beam penumbra is often desired for producing steep dose fall-off between the target volume and adjacent critical structures. Due to limited source sizes and the scattering effects, the physical penumbra of the Gamma Knife (GK) is often restricted to a width of 1-2 mm. In this work, we developed a technique to further reduce the beam penumbra and improve the dose profile for the Gamma Knife delivery. Under this technique, a conic filter is inserted into an individual plug collimator of a GK helmet to flatten the beam profile. Monte Carlo calculations were carried out to simulate the GK geometry of the individual plug collimator and to optimize the physical shapes of the filters. The calculations were performed for a series of filter shapes with different collimator sizes. Our results show that a proper filter significantly reduces the single GK beam penumbra width (defined as the distance from the 90% to 50% isodose lines) by 30-60%. The beam intensity is reduced by about 20-50% when the filter is used. A treatment plan was developed for a trigeminal neuralgia case by commissioning the filtered beam profile for Leksell Gamma Plan (version 5.31). Compared with the conventional treatment plan, a significant improvement was found on the critical structure sparing and on the target dose uniformity. In conclusion, the proposed technique is feasible and effective in sharpening the beam penumbra for Gamma Knife beam profiles.

  8. Application of the gamma evaluation method in Gamma Knife film dosimetry

    SciTech Connect

    Park, Jeong-Hoon; Han, Jung Ho; Kim, Chae-Yong; Oh, Chang Wan; Lee, Do-Heui; Suh, Tae-Suk; Gyu Kim, Dong; Chung, Hyun-Tai

    2011-10-15

    Purpose: Gamma Knife (GK) radiosurgery is a minimally invasive surgical technique for the treatment of intracranial lesions. To minimize neurological deficits, submillimeter accuracy is required during treatment delivery. In this paper, the delivery accuracy of GK radiosurgery was assessed with the gamma evaluation method using planning dose distribution and film measurement data. Methods: Single 4, 8, and 16 mm and composite shot plans were developed for evaluation using the GK Perfexion (PFX) treatment planning system (TPS). The planning dose distributions were exported as digital image communications in medicine - radiation therapy (DICOM RT) files using a new function of GK TPS. A maximum dose of 8 Gy was prescribed for four test plans. Irradiation was performed onto a spherical solid water phantom using Gafchromic EBT2 films in the axial and coronal planes. The exposed films were converted to absolute dose based on a 4th-order polynomial calibration curve determined using ten calibration films. The film measurement results and planning dose distributions were registered for further analysis in the same Leksell coordinate using in-house software. The gamma evaluation method was applied to two dose distributions with varying spatial tolerance (0.3-2.0 mm) and dosimetric tolerance (0.3-2.0%), to verify the accuracy of GK radiosurgery. The result of gamma evaluation was assessed using pass rate, dose gamma index histogram (DGH), and dose pass rate histogram (DPH). Results: The 20, 50, and 80% isodose lines found in film measurements were in close agreement with the planning isodose lines, for all dose levels. The comparison of diagonal line profiles across the axial plane yielded similar results. The gamma evaluation method resulted in high pass rates of >95% within the 50% isodose line for 0.5 mm/0.5% tolerance criteria, in both the axial and coronal planes. They satisfied 1.0 mm/1.0% criteria within the 20% isodose line. Our DGH and DPH also showed that low

  9. Three-dimensional radiation dosimetry for gamma knife using a gel dosimeter

    NASA Astrophysics Data System (ADS)

    Hussain, Kazi Muazzam

    The use of three-dimensional radiation dosimetry has been limited. With the use of water phantoms and ionization chambers, it has been possible to determine three dimensional dose distributions on a gross scale for cobalt 60 and linear accelerator sources. This method has been somewhat useful for traditional radiotherapy. There is, however, a need for more precise dosimetry, particularly with stereotactic radiosurgery. Most gamma knife facilities use either thermoluminescant dosimetry or film, neither of which provides three dimensional dose distributions. To overcome this limitation, we have developed a gel dosimetry system that relies on the production of a ferric ion-xylenol orange colored complex. This work demonstrates the use of laser light and a detector to quantify radiation-induced colorimetric changes in absorbance for the gel dosimeter. The absorbance has been reconstructed by the back projection technique to demonstrate the applicability of the gel dosimeter to gamma knife 3D-dose distributions.

  10. TH-A-9A-06: Inverse Planning of Gamma Knife Radiosurgery Using Natural Physical Models

    SciTech Connect

    Riofrio, D; Ma, L; Zhou, J; Luan, S

    2014-06-15

    Purpose: Treatment-planning systems rely on computer intensive optimization algorithms in order to provide radiation dose localization. We are investigating a new optimization paradigm based on natural physical modeling and simulations, which tend to evolve in time and find the minimum energy state. In our research, we aim to match physical models with radiation therapy inverse planning problems, where the minimum energy state coincides with the optimal solution. As a prototype study, we have modeled the inverse planning of Gamma Knife radiosurgery using the dynamic interactions between charged particles and demonstrate the potential of the paradigm. Methods: For inverse planning of Gamma Knife radiosurgery: (1) positive charges are uniformly placed on the surface of tumors and critical structures. (2) The Gamma Knife dose kernels of 4mm, 8mm and 16mm radii are modeled as geometric objects with variable charges. (3) The number of shots per each kernel radii is obtained by solving a constrained integer-linear problem. (4) The shots are placed into the tumor volume and move under electrostatic forces. The simulation is performed until internal forces are zero or maximum iterations are reached. (5) Finally, non-negative least squares (NNLS) is used to calculate the beam-on times for each shot. Results: A 3D C-shaped tumor surrounding a spherical critical structure was used for testing the new optimization paradigm. These tests showed that charges spread out evenly covering the tumor while keeping distance from the critical structure, resulting in a high quality plan. Conclusion: We have developed a new paradigm for dose optimization based on the simulation of physical models. As prototype studies, we applied electrostatic models to Gamma Knife radiosurgery and demonstrated the potential of the new paradigm. Further research and fine-tuning of the model are underway. NSF CBET-0853157.

  11. Gamma Knife Radiosurgery for Treatment of Cerebral Metastases From Non-Small-Cell Lung Cancer

    SciTech Connect

    Motta, Micaela; Vecchio, Antonella del; Attuati, Luca; Picozzi, Piero; Perna, Lucia; Franzin, Alberto; Bolognesi, Angelo; Cozzarini, Cesare; Calandrino, Riccardo; Mortini, Pietro; Muzio, Nadia di

    2011-11-15

    Purpose: To evaluate clinical and physico-dosimetric variables affecting clinical outcome of patients treated with Gamma Knife radiosurgery (GKRS) for brain metastases from non-small cell lung cancer (NSCLC). Methods and Materials: Between 2001 and 2006, 373 patients (298 men and 75 women, median age 65 years) with brain metastases from NSCLC underwent GKRS. All of them had KPS {>=} 60%, eight or fewer brain metastases, confirmed histopathological diagnosis and recent work-up (<3 months). Thirty-five patients belonged to recursive partitioning analysis (RPA) Class I, 307 patients were in RPA Class II, 7 patients were in RPA Class III. Median tumor volume was 3.6 cm{sup 3}. Median marginal dose was 22.5 Gy at 50% isodose.; median 10 Gy and 12 Gy isodose volumes were 30.8 cm{sup 3} and 15.8 cm{sup 3}, respectively. Follow-up with MRI was performed every 3 months. Overall survival data were collected from internal database, telephone interviews, and identifying registries. Results: Mean follow-up after GKRS was 51 months (range, 6 to 96 months); mean overall survival was 14.2 months. Of 373 patients, 29 were alive at time of writing, 104 had died of cerebral progression, and 176 had died of systemic progression. In 64 cases it was not possible to ascertain the cause. Univariate and multivariate analysis were adjusted for the following: RPA class, surgery, WBRT, age, gender, number of lesions, median tumor volume, median peripheral dose, and 10 Gy and 12 Gy volumes. Identified RPA class and overall tumor volume >5 cc were the only two covariates independently predictive of overall survival in patients who died of cerebral progression. Conclusions: Global volume of brain disease should be the main parameter to consider for performing GKRS, which is a first-line therapy for patient in good general condition and controlled systemic disease.

  12. Accuracy and stability of positioning in radiosurgery: long-term results of the Gamma Knife system.

    PubMed

    Heck, Bernhard; Jess-Hempen, Anja; Kreiner, Hans Jürg; Schöpgens, Hans; Mack, Andreas

    2007-04-01

    The primary aim of this investigation was to determine the long term overall accuracy of an irradiation position of Gamma Knife systems. The mechanical accuracy of the system as well as the overall accuracy of an irradiation position was examined by irradiating radiosensitive films. To measure the mechanical accuracy, the GafChromic film was fixed by a special tool at the unit center point (UCP). For overall accuracy the film was mounted inside a phantom at a target position given by a two-dimensional cross. Its position was determined by CT or MRI scans, a treatment was planned to hit this target by use of the standard planning software and the radiation was finally delivered. This procedure is named "system test" according to DIN 6875-1 and is equivalent to a treatment simulation. The used GafChromic films were evaluated by high resolution densitometric measurements. The Munich Gamma Knife UCP coincided within x; y; z: -0.014 +/- 0.09 mm; 0.013 +/- 0.09 mm; -0.002 +/- 0.06 mm (mean +/- SD) to the center of dose distribution. There was no trend in the measured data observed over more than ten years. All measured data were within a sphere of 0.2 mm radius. When basing the target definition in the system test on MRI scans, we obtained an overall accuracy of an irradiation position in the x direction of 0.21 +/- 0.32 mm and in the y direction 0.15 +/- 0.26 mm (mean +/- SD). When a CT-based target definition was used, we measured distances in x direction 0.06 +/- 0.09 mm and in y direction 0.04 +/- 0.09 mm (mean +/- SD), respectively. These results were compared with those obtained with a Gamma Knife equipped with an automatic positioning system (APS) by use of a different phantom. This phantom was found to be slightly less accurate due to its mechanical construction and the soft fixation into the frame. The phantom related position deviation was found to be about +/- 0.2 mm, and therefore the measured accuracy of the APS Gamma Knife was evidently less precise by

  13. A simple and effective method for validation and measurement of collimator output factors for Leksell Gamma Knife® Perfexion™

    NASA Astrophysics Data System (ADS)

    Ma, Lijun; Kjäll, Per; Novotny, Josef Jr; Nordström, Håkan; Johansson, Jonas; Verhey, Lynn

    2009-06-01

    Accurate determination of collimator output factors is important for Leksell Gamma Knife radiosurgery. The new Leksell Gamma Knife® Perfexion™ system has a completely redesigned collimator system and the collimator output factors are different from the other Leksell Gamma Knife® models. In this study, a simple method was developed to validate the collimator output factors specifically for Leksell Gamma Knife® Perfexion™. The method uses double-shot exposures on a single film to eliminate repeated setups and the necessity to acquire dose calibration curves required for the traditional film exposure method. Using the method, the collimator output factors with respect to the 16 mm collimator were measured to be 0.929 ± 0.009 and 0.817 ± 0.012 for the 8 mm and the 4 mm collimator, respectively. These values are in agreement (within 2%) with the default values of 0.924 and 0.805 in the Leksell Gamma Plan® treatment planning system. These values also agree with recently published results of 0.917 (8 mm collimator) and 0.818 (4 mm collimator) obtained from the traditional methods. Given the efficiency of the method, measurement and validation of the collimator output factors can be readily adopted in commissioning and quality assurance of a Leksell Gamma Knife® Perfexion™ system.

  14. Cold knife cone biopsy

    MedlinePlus

    A cold knife cone biopsy (conization) is surgery to remove a sample of abnormal tissue from the cervix. The ... Cold knife cone biopsy is done to detect cervical cancer or early changes that lead to cancer. ...

  15. Cold knife cone biopsy

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003910.htm Cold knife cone biopsy To use the sharing features on this page, please enable JavaScript. A cold knife cone biopsy (conization) is surgery to remove ...

  16. Verification of Gamma Knife extend system based fractionated treatment planning using EBT2 film

    SciTech Connect

    Natanasabapathi, Gopishankar; Bisht, Raj Kishor

    2013-12-15

    Purpose: This paper presents EBT2 film verification of fractionated treatment planning with the Gamma Knife (GK) extend system, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery.Methods: A human head shaped phantom simulated the verification process for fractionated Gamma Knife treatment. Phantom preparation for Extend Frame based treatment planning involved creating a dental impression, fitting the phantom to the frame system, and acquiring a stereotactic computed tomography (CT) scan. A CT scan (Siemens, Emotion 6) of the phantom was obtained with following parameters: Tube voltage—110 kV, tube current—280 mA, pixel size—0.5 × 0.5 and 1 mm slice thickness. A treatment plan with two 8 mm collimator shots and three sectors blocking in each shot was made. Dose prescription of 4 Gy at 100% was delivered for the first fraction out of the two fractions planned. Gafchromic EBT2 film (ISP Wayne, NJ) was used as 2D verification dosimeter in this process. Films were cut and placed inside the film insert of the phantom for treatment dose delivery. Meanwhile a set of films from the same batch were exposed from 0 to 12 Gy doses for calibration purposes. An EPSON (Expression 10000 XL) scanner was used for scanning the exposed films in transparency mode. Scanned films were analyzed with inhouse written MATLAB codes.Results: Gamma index analysis of film measurement in comparison with TPS calculated dose resulted in high pass rates >90% for tolerance criteria of 1%/1 mm. The isodose overlay and linear dose profiles of film measured and computed dose distribution on sagittal and coronal plane were in close agreement.Conclusions: Through this study, the authors propose treatment verification QA method for Extend frame based fractionated Gamma Knife radiosurgery using EBT2 film.

  17. SU-E-T-536: Inhomogeneity Correction in Planning of Gamma Knife Treatments for Acoustic Schwannoma

    SciTech Connect

    Lu, L; Gupta, N; Hessler, J; Liu, A; Weldon, M; McGregor, J; Ammirati, M; Guiou, M; Xia, F; Grecula, J

    2014-06-01

    Purpose: To find out the dose difference on targets and organs at risk for the treatment of acoustic schwannoma if the inhomogeneity correction (Convolution algorithm) is applied. Methods: Images of patients treated for acoustic schwannoma with Gamma Knife using TMR 10 algorithm were retrieved from database and replanned with Convolution and TMR 10 algorithm respectively. These patients were treated using a preplan scheme in following: (1) Before the actual treatment day, using the MRI image that was taken without a head frame on the patient's skull, a pre-treatment plan was made based on the default skull coordinates in the Gamma Knife treatment planning system (LGP); (2) then on treatment day, a head frame was placed on the patient's skull, and a CT image was taken. The CT image with head frame was registered and fused with the completed preplan; (3) the treatment plan was finalized and the treatment was delivered. To find out the dosimetry impact of inhomogeneity correction, we used the retrieved CT images to replan the treatment using Convolution algorithm in LGP software version 10.1.1. The dose distributions and the dose volume histograms for targets and OARs were compared for these two dose calculation algorithms. Results: The dose calculated with the Convolution algorithm in general is slightly lower than the one from TMR 10 around the boney area. The effect from the inhomogeneity correction is observable but not significant, and varies with the location of the tumor. Conclusion: Inhomogeneity correction slightly improve the dose accuracy for acoustic schwannoma Gamma Knife treatments although the correction may not be very significant. Our Result provides evidence for dose prescription adjustment to treat acoustic schwannoma. The actual clinical outcome of switching from using TMR10 to using Convolution needs to be further investigated.

  18. Clinical Evaluation of Targeting Accuracy of Gamma Knife Radiosurgery in Trigeminal Neuralgia

    SciTech Connect

    Massager, Nicolas Abeloos, Laurence; Devriendt, Daniel; Op de Beeck, Marc; Levivier, Marc

    2007-12-01

    Purpose: The efficiency of radiosurgery is related to its highly precise targeting. We assessed clinically the targeting accuracy of radiosurgical treatment with the Leksell Gamma Knife for trigeminal neuralgia. We also studied the applied radiation dose within the area of focal contrast enhancement on the trigeminal nerve root following radiosurgery. Methods and Materials: From an initial group of 78 patients with trigeminal neuralgia treated with gamma knife radiosurgery using a 90-Gy dose, we analyzed a subgroup of 65 patients for whom 6-month follow-up MRI showed focal contrast enhancement of the trigeminal nerve. Follow-up MRI was spatially coregistered to the radiosurgical planning MRI. Target accuracy was assessed from deviation of the coordinates of the intended target compared with the center of enhancement on postoperative MRI. Radiation dose delivered at the borders of contrast enhancement was evaluated. Results: The median deviation of the coordinates between the intended target and the center of contrast enhancement was 0.91 mm in Euclidean space. The radiation doses fitting within the borders of the contrast enhancement of the trigeminal nerve root ranged from 49 to 85 Gy (median value, 77 {+-} 8.7 Gy). Conclusions: The median deviation found in clinical assessment of gamma knife treatment for trigeminal neuralgia is low and compatible with its high rate of efficiency. Focal enhancement of the trigeminal nerve after radiosurgery occurred in 83% of our patients and was not associated with clinical outcome. Focal enhancement borders along the nerve root fit with a median dose of 77 {+-} 8.7 Gy.

  19. Benchmark Experiment of Dose Rate Distributions Around the Gamma Knife Medical Apparatus

    SciTech Connect

    Oishi, K.; Kosako, K.; Kobayashi, Y.; Sonoki, I.

    2014-06-15

    Dose rate measurements around a gamma knife apparatus were performed by using an ionization chamber. Analyses have been performed by using the Monte Carlo code MCNP-5. The nuclear library used for the dose rate distribution of {sup 60}Co was MCPLIB04. The calculation model was prepared with a high degree of fidelity, such as the position of each Cobalt source and shielding materials. Comparisons between measured results and calculated ones were performed, and a very good agreement was observed. It is concluded that the Monte Carlo calculation method with its related nuclear data library is very effective for such a complicated radiation oncology apparatus.

  20. Benchmark Experiment of Dose Rate Distributions Around the Gamma Knife Medical Apparatus

    NASA Astrophysics Data System (ADS)

    Oishi, K.; Kosako, K.; Kobayashi, Y.; Sonoki, I.

    2014-06-01

    Dose rate measurements around a gamma knife apparatus were performed by using an ionization chamber. Analyses have been performed by using the Monte Carlo code MCNP-5. The nuclear library used for the dose rate distribution of 60Co was MCPLIB04. The calculation model was prepared with a high degree of fidelity, such as the position of each Cobalt source and shielding materials. Comparisons between measured results and calculated ones were performed, and a very good agreement was observed. It is concluded that the Monte Carlo calculation method with its related nuclear data library is very effective for such a complicated radiation oncology apparatus.

  1. Phantom Positioning Variation in the Gamma Knife® Perfexion Dosimetry

    NASA Astrophysics Data System (ADS)

    Costa, N. A.; Potiens, M. P. A.; Saraiva, C. W. C.

    2016-07-01

    The use of small volume ionization chamber has become required for the dosimetry of equipments that use small radiation fields such as the Gamma Knife® Perfexion (GKP) unit. In this work, a pinpoint ionization chamber was inserted into the dosimetry phantom and measurements were performed with the phantom in different positions, in order to verify if the change in the phantom positioning affects the dosimetry of the GKP. Four different phantom positions were performed. The variation in the result is within the range allowed for the dosimetry of a GKP equipment.

  2. The use of a Leksell-BRW adapter for linac radiosurgery as an adjunct to Gamma Knife treatment

    NASA Astrophysics Data System (ADS)

    Ekstrand, Kenneth E.; Hinson, William H.; Bourland, J. Daniel; de Guzman, Allan F.; Stieber, Volker W.; Tatter, Steven B.; Ellis, Thomas L.

    2003-12-01

    We have investigated the use of an adapter that permits the use of a Leksell coordinate frame with a linear accelerator stereotactic radiosurgery system based on the Brown-Robert-Wells (BRW) design. This device is useful when lesions that are planned for treatment on a Leksell Gamma Knife system are found to be inaccessible to the Gamma Knife. We have found that with this device objects within a head phantom can be targeted by the linear accelerator within an accuracy of approximately 1 mm.

  3. Gamma Knife irradiation method based on dosimetric controls to target small areas in rat brains

    SciTech Connect

    Constanzo, Julie; Paquette, Benoit; Charest, Gabriel; Masson-Côté, Laurence; Guillot, Mathieu

    2015-05-15

    Purpose: Targeted and whole-brain irradiation in humans can result in significant side effects causing decreased patient quality of life. To adequately investigate structural and functional alterations after stereotactic radiosurgery, preclinical studies are needed. The purpose of this work is to establish a robust standardized method of targeted irradiation on small regions of the rat brain. Methods: Euthanized male Fischer rats were imaged in a stereotactic bed, by computed tomography (CT), to estimate positioning variations relative to the bregma skull reference point. Using a rat brain atlas and the stereotactic bregma coordinates obtained from CT images, different regions of the brain were delimited and a treatment plan was generated. A single isocenter treatment plan delivering ≥100 Gy in 100% of the target volume was produced by Leksell GammaPlan using the 4 mm diameter collimator of sectors 4, 5, 7, and 8 of the Gamma Knife unit. Impact of positioning deviations of the rat brain on dose deposition was simulated by GammaPlan and validated with dosimetric measurements. Results: The authors’ results showed that 90% of the target volume received 100 ± 8 Gy and the maximum of deposited dose was 125 ± 0.7 Gy, which corresponds to an excellent relative standard deviation of 0.6%. This dose deposition calculated with GammaPlan was validated with dosimetric films resulting in a dose-profile agreement within 5%, both in X- and Z-axes. Conclusions: The authors’ results demonstrate the feasibility of standardizing the irradiation procedure of a small volume in the rat brain using a Gamma Knife.

  4. Gamma Knife Radiosurgery as a Therapeutic Strategy for Intracranial Sarcomatous Metastases

    SciTech Connect

    Flannery, Thomas; Kano, Hideyuki; Niranjan, Ajay M.Ch.; Monaco, Edward A.; Flickinger, John C.; Kofler, Julia; Lunsford, L. Dade; Kondziolka, Douglas

    2010-02-01

    Purpose: To determine the indication and outcomes for Gamma Knife stereotactic radiosurgery (GKSRS) in the care of patients with intracranial sarcomatous metastases. Methods and Materials: Data from 21 patients who underwent radiosurgery for 60 sarcomatous intracranial metastases (54 parenchymal and 6 dural-based) were studied. Nine patients had radiosurgery for solitary tumors and 12 for multiple tumors. The primary pathology was metastatic leiomyosarcoma (4 patients), osteosarcoma (3 patients), soft-tissue sarcoma (5 patients), chondrosarcoma (2 patients), alveolar soft part sarcoma (2 patients), and rhabdomyosarcoma, Ewing's sarcoma, liposarcoma, neurofibrosarcoma, and synovial sarcoma (1 patient each). Twenty patients received multimodality management for their primary tumor, and 1 patient had no evidence of systemic disease. The mean tumor volume was 6.2 cm{sup 3} (range, 0.07-40.9 cm{sup 3}), and a median margin dose of 16 Gy was administered. Three patients had progressive intracranial disease despite fractionated whole-brain radiotherapy before SRS. Results: A local tumor control rate of 88% was achieved (including patients receiving boost, up-front, and salvage SRS). New remote brain metastases developed in 7 patients (33%). The median survival after diagnosis of intracranial metastasis was 16 months, and the 1-year survival rate was 61%. Conclusions: Gamma Knife radiosurgery was a well-tolerated and initially effective therapy in the management of patients with sarcomatous intracranial metastases. However, many patients, including those who also received fractionated whole-brain radiotherapy, developed progressive new brain disease.

  5. Treatment of high numbers of brain metastases with Gamma Knife radiosurgery: a review.

    PubMed

    Hatiboglu, Mustafa Aziz; Tuzgen, Saffet; Akdur, Kerime; Chang, Eric L

    2016-04-01

    Effectiveness of stereotactic radiosurgery (SRS) has been shown in patients with one to four brain metastases. Work has been done to evaluate the role of SRS alone treatment without whole-brain radiation therapy in patients with more than four metastases. A recent multiinstitutional JLGK 0901 prospective study revealed the class-2 evidence that SRS without whole-brain radiation therapy is an effective treatment for patients up to 10 metastatic lesions. Several retrospective studies exist to show the efficacy and safety of SRS for patients with even more than 10 lesions. However, patient selection is very critical for SRS alone treatment. The PubMed database was searched using combinations of search terms and synonyms for multiple brain metastases, Gamma Knife and SRS published between January 1, 2005 and January 1, 2015 in order to address the effectiveness of Gamma Knife for patients with multiple brain metastases. Good performance status, controlled primary disease, total treated tumor volume of 15 cm(3) or less have been found to be significant predictors for survival among patients with two or more brain lesions. The data suggest that SRS can be used and whole brain radiation therapy can be withheld in selected patients with multiple lesions to avoid acute or chronic adverse effects, especially neurocognitive decline, without causing survival disadvantage. In this review, we assessed the evidence for SRS treatment of patients with multiple brain metastases. PMID:26811300

  6. Gamma Knife 3-D dose distribution near the area of tissue inhomogeneities by normoxic gel dosimetry

    SciTech Connect

    Isbakan, Fatih; Uelgen, Yekta; Bilge, Hatice; Ozen, Zeynep; Agus, Onur; Buyuksarac, Bora

    2007-05-15

    The accuracy of the Leksell GammaPlan registered , the dose planning system of the Gamma Knife Model-B, was evaluated near tissue inhomogeneities, using the gel dosimetry method. The lack of electronic equilibrium around the small-diameter gamma beams can cause dose calculation errors in the neighborhood of an air-tissue interface. An experiment was designed to investigate the effects of inhomogeneity near the paranosal sinuses cavities. The homogeneous phantom was a spherical glass balloon of 16 cm diameter, filled with MAGIC gel; i.e., the normoxic polymer gel. Two hollow PVC balls of 2 cm radius, filled with N{sub 2} gas, represented the air cavities inside the inhomogeneous phantom. For dose calibration purposes, 100 ml gel-containing vials were irradiated at predefined doses, and then scanned in a MR unit. Linearity was observed between the delivered dose and the reciprocal of the T2 relaxation time constant of the gel. Dose distributions are the results of a single shot of irradiation, obtained by collimating all 201 cobalt sources to a known target in the phantom. Both phantoms were irradiated at the same dose level at the same coordinates. Stereotactic frames and fiducial markers were attached to the phantoms prior to MR scanning. The dose distribution predicted by the Gamma Knife planning system was compared with that of the gel dosimetry. As expected, for the homogeneous phantom the isodose diameters measured by the gel dosimetry and the GammaPlan registered differed by 5% at most. However, with the inhomogeneous phantom, the dose maps in the axial, coronal and sagittal planes were spatially different. The diameters of the 50% isodose curves differed 43% in the X axis and 32% in the Y axis for the Z=90 mm axial plane; by 44% in the X axis and 24% in the Z axis for the Y=90 mm coronal plane; and by 32% in the Z axis and 42% in the Y axis for the X=92 mm sagittal plane. The lack of ability of the GammaPlan registered to predict the rapid dose fall off, due

  7. Gamma Knife 3-D dose distribution near the area of tissue inhomogeneities by normoxic gel dosimetry.

    PubMed

    Isbakan, Fatih; Ulgen, Yekta; Bilge, Hatice; Ozen, Zeynep; Agus, Onur; Buyuksarac, Bora

    2007-05-01

    The accuracy of the Leksell GammaPlan, the dose planning system of the Gamma Knife Model-B, was evaluated near tissue inhomogeneities, using the gel dosimetry method. The lack of electronic equilibrium around the small-diameter gamma beams can cause dose calculation errors in the neighborhood of an air-tissue interface. An experiment was designed to investigate the effects of inhomogeneity near the paranosal sinuses cavities. The homogeneous phantom was a spherical glass balloon of 16 cm diameter, filled with MAGIC gel; i.e., the normoxic polymer gel. Two hollow PVC balls of 2 cm radius, filled with N2 gas, represented the air cavities inside the inhomogeneous phantom. For dose calibration purposes, 100 ml gel-containing vials were irradiated at predefined doses, and then scanned in a MR unit. Linearity was observed between the delivered dose and the reciprocal of the T2 relaxation time constant of the gel. Dose distributions are the results of a single shot of irradiation, obtained by collimating all 201 cobalt sources to a known target in the phantom. Both phantoms were irradiated at the same dose level at the same coordinates. Stereotactic frames and fiducial markers were attached to the phantoms prior to MR scanning. The dose distribution predicted by the Gamma Knife planning system was compared with that of the gel dosimetry. As expected, for the homogeneous phantom the isodose diameters measured by the gel dosimetry and the GammaPlan differed by 5% at most. However, with the inhomogeneous phantom, the dose maps in the axial, coronal and sagittal planes were spatially different. The diameters of the 50% isodose curves differed 43% in the X axis and 32% in the Y axis for the Z =90 mm axial plane; by 44% in the X axis and 24% in the Z axis for the Y=90 mm coronal plane; and by 32% in the Z axis and 42% in the Y axis for the X=92 mm sagittal plane. The lack of ability of the GammaPlan to predict the rapid dose fall off, due to the air cavities behind or near the

  8. Gamma Knife Radiosurgery for Skull Base Meningiomas: Long-Term Radiologic and Clinical Outcome

    SciTech Connect

    Han, Jung Ho; Kim, Dong Gyu Chung, Hyun-Tai; Park, Chul-Kee; Paek, Sun Ha; Kim, Chae-Yong; Jung, Hee-Won

    2008-12-01

    Purpose: To analyze the long-term outcomes in patients with skull base meningiomas (SBMNGs) treated with Gamma Knife radiosurgery (GKRS). Methods and Materials: Of the 98 consecutive patients with SBMNGs treated with GKRS between 1998 and 2002, 63 were followed up for more than 48 months. The mean ({+-}SD) age of the patients was 50 {+-} 12 years, the mean tumor volume was 6.5 cm{sup 3} (range, 0.5-18.4 cm{sup 3}), the mean marginal dose was 12.6 Gy (range, 7.0-20.0 Gy), and the mean follow-up duration was 77 {+-} 18 months. The mean number of shots was 13.7 {+-} 3.8. The tumor volume was decreased at the last follow-up in 28 patients (44.4%) and increased in 6 (9.6%). The actuarial tumor control rate was 90.2% at 5 years. No notable prognostic factor related to tumor control was identified. Ten patients (15.9%) with a cranial neuropathy showed unfavorable outcomes. The rate of improvement in patients with a cranial neuropathy was 45.1%. Age >70 years was likely correlated with an unfavorable outcome in patients with cranial neuropathy (odds ratio = 0.027; p = 0.025; 95% confidence interval 0.001-0.632). Cavernous sinus location was significantly associated with improvement of a cranial neuropathy (odds ratio = 7.314; p = 0.007; 95% confidence interval 1.707-31.34). Conclusions: Gamma Knife radiosurgery is an effective modality for the treatment of SBMNGs and provides favorable outcomes in patients with cranial neuropathy, even in the long-term follow-up period. However, radiosurgery for patients with no or only mild symptoms should be performed cautiously because neither complication rate is low enough to be negligible, especially in elderly patients. A cranial neuropathy by MNGs involving the cavernous sinus seems to have a higher chance of improvement after radiosurgery than other SBMNGs.

  9. Development of a 3-dimensional dosimetry system for Leksell Gamma Knife Perfexion

    NASA Astrophysics Data System (ADS)

    Yoon, KyoungJun; Kwak, JungWon; Lee, DoHeui; Cho, ByungChul; Lee, SangWook; Ahn, SeungDo

    2015-07-01

    The purpose of our study is to develop a new, 3-dimensional dosimetry system to verify the accuracy of dose deliveries in Leksell Gamma Knife Perfexion (LGKP) (Elekta, Norcross, GA, USA). The instrument consists of a moving head phantom, an embedded thin active layer and a CCD camera system and was designed to be mounted to LGKP. As an active material concentrically located in the hemispheric head phantom, we choose Gafchromic EBT3 films and Gd2O2S:Tb phosphor sheets for dosimetric measurements. Also, to compensate for the lack of backscatter, we located a 1-cm-thick poly methyl methacrylate (PMMA) plate downstream of the active layer. The PMMA plate was transparent to scintillation light to reach the CCD with 1200 × 1200 pixels and a 5.2 µm pitch. With this system, 300 images with a 0.2-mm slice gap were acquired under each of three collimator setups, i.e. 4-mm, 8-mm, and 16-mm, respectively. The 2D projected images taken by the CCD camera were compared with the dose distributions measured by the EBT3 films under the same conditions. All 2D distributions were normalized to the maximum values derived by fitting peaks for each collimator setup. The differences in the full widths at half maximum (FWHM) of 2D profiles between CCD images and film doses were measured to be less than 0.3-mm. The scanning task for all peak regions took less than three minutes with the new instrument. So it can be utilized as a QA tool for the Gamma knife radiosurgery system instead of film dosimetry, the use of which requires much more time and many more resources.

  10. An efficient method of measuring the 4 mm helmet output factor for the Gamma Knife

    NASA Astrophysics Data System (ADS)

    Ma, Lijun; Li, X. Allen; Yu, Cedric X.

    2000-03-01

    It is essential to have accurate measurements of the 4 mm helmet output factor in the treatment of trigeminal neuralgia patients using the Gamma Knife. Because of the small collimator size and the sharp dose gradient at the beam focus, this measurement is generally tedious and difficult. We have developed an efficient method of measuring the 4 mm helmet output factor using regular radiographic films. The helmet output factor was measured by exposing a single Kodak XV film in the standard Leksell spherical phantom using the 18 mm helmet with 30-40 of its plug collimators replaced by the 4 mm plug collimators. The 4 mm helmet output factor was measured to be 0.876 ± 0.009. This is in excellent agreement with our EGS4 Monte Carlo simulated value of 0.876 ± 0.005. This helmet output factor value also agrees with more tedious TLD, diode and radiochromic film measurements that were each obtained using two separate measurements with the 18 mm helmet and the 4 mm helmet respectively. The 4 mm helmet output factor measured by the diode was 0.884 ± 0.016, and the TLD measurement was 0.890 ± 0.020. The radiochromic film measured value was 0.870 ± 0.018. Because a single-exposure measurement was performed instead of a double-exposure measurement, most of the systematic errors that appeared in the double-exposure measurements due to experimental setup variations were cancelled out. Consequently, the 4 mm helmet output factor is more precisely determined by the single-exposure approach. Therefore, routine measurement and quality assurance of the 4 mm helmet output factor of the Gamma Knife could be efficiently carried out using the proposed single-exposure technique.

  11. Gamma-Knife radiosurgery in the management of melanoma patients with brain metastases: A series of 106 patients without whole-brain radiotherapy

    SciTech Connect

    Gaudy-Marqueste, Caroline . E-mail: marqueste@wanadoo.fr; Regis, Jean-Marie; Muracciole, Xavier; Laurans, Renaud; Richard, Marie-Aleth; Bonerandi, Jean-Jacques; Grob, Jean-Jacques

    2006-07-01

    Purpose: To assess retrospectively a strategy that uses Gamma-Knife radiosurgery (GKR) in the management of patients with brain metastases (BMs) of malignant melanoma (MM). Methods: GKR without whole-brain radiotherapy (WBRT) was performed for patients with Karnofsky Performance Status (KPS) of 60 or above who harbored 1 to 4 BMs of 30 mm or less and was repeated as often as needed. Survival was assessed in the whole population, whereas local-control rates were assessed for patients with follow-up longer than 3 months. Results: A total of 221 BMs were treated in 106 patients; 61.3% had a single BM. Median survival from the time of GKR was 5.09 months. Control rate of treated BMs was 83.7%, with 14% of complete response (14 BMs), 42% of partial response (41 BMs), and 43% of stabilization (43 BMs). In multivariate analysis, survival prognosis factors retained were KPS greater than 80, cortical or subcortical location, and Score Index for Radiosurgery (SIR) greater than 6. On the basis of KPS, BM location, and age, a score called MM-GKR, predictive of survival in our population, was defined. Conclusion: Gamma-Knife radiosurgery provides a surgery-like ability to obtain control of a solitary BM and could be consider as an alternative treatment to the combination of GKR+WBRT as a palliative strategy. MM-GKR classification is more adapted to MM patients than are SIR, RPA and Brain Score for Brain Metastasis.

  12. Early versus late Gamma Knife radiosurgery following transsphenoidal resection for nonfunctioning pituitary macroadenomas: a matched cohort study.

    PubMed

    Pomeraniec, I Jonathan; Dallapiazza, Robert F; Xu, Zhiyuan; Jane, John A; Sheehan, Jason P

    2016-07-01

    OBJECT Gamma Knife radiosurgery (GKRS) is frequently employed to treat residual or recurrent nonfunctioning pituitary macroadenomas. There is no consensus as to whether GKRS should be used early after surgery or if radiosurgery should be withheld until there is evidence of radiographic progression of tumor. METHODS This is a retrospective review of patients with nonfunctioning pituitary macroadenomas who underwent transsphenoidal surgery followed by GKRS between 1996 and 2013 at the University of Virginia Health System. Patients were stratified based on the interval between resection and radiosurgery. Operative results and imaging and clinical outcomes were compared across groups following early (≤ 6 months) or late (> 6 months) radiosurgery. RESULTS Sixty-four patients met the study criteria and were grouped based on early (n = 32) or late (n = 32) GKRS following transsphenoidal resection. There was a greater risk of tumor progression after GKRS in the late radiosurgical group (p = 0.027) over a median radiographic follow-up period of 68.5 months. Furthermore, there was a significantly higher occurrence of post-GKRS endocrinopathy in the late radiosurgical cohort (p = 0.041). Seventeen percent of patients without endocrinopathy in the early cohort developed new endocrinopathies during the follow-up period versus 64% in the late cohort (p = 0.036). This difference was primarily due to a significantly higher rate of tumor growth during the observation period of the late treatment cohort (p = 0.014). Of these patients with completely new endocrinopathies, radiation-associated pituitary insufficiency developed in 1 of 2 patients in the early group and in 3 of 7 (42.9%) patients in the late group. CONCLUSIONS Early treatment with GKRS appears to decrease the rate of radiographic and symptomatic progression of subtotally resected nonfunctioning pituitary macroadenomas compared with late GKRS treatment after a period of expectant management. Delaying radiosurgery may

  13. Assessment of absorbed dose to thyroid, parotid and ovaries in patients undergoing Gamma Knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Hasanzadeh, H.; Sharafi, A.; Allah Verdi, M.; Nikoofar, A.

    2006-09-01

    Stereotactic radiosurgery was originally introduced by Lars Leksell in 1951. This treatment refers to the noninvasive destruction of an intracranial target localized stereotactically. The purpose of this study was to identify the dose delivered to the parotid, ovaries, testis and thyroid glands during the Gamma Knife radiosurgery procedure. A three-dimensional, anthropomorphic phantom was developed using natural human bone, paraffin and sodium chloride as the equivalent tissue. The phantom consisted of a thorax, head and neck and hip. In the natural places of the thyroid, parotid (bilateral sides) and ovaries (midline), some cavities were made to place TLDs. Three TLDs were inserted in a batch with 1 cm space between the TLDs and each batch was inserted into a single cavity. The final depth of TLDs was 3 cm from the surface for parotid and thyroid and was 15 cm for the ovaries. Similar batches were placed superficially on the phantom. The phantom was gamma irradiated using a Leksell model C Gamma Knife unit. Subsequently, the same batches were placed superficially over the thyroid, parotid, testis and ovaries in 30 patients (15 men and 15 women) who were undergoing radiosurgery treatment for brain tumours. The mean dosage for treating these patients was 14.48 ± 3.06 Gy (10.5-24 Gy) to a mean tumour volume of 12.30 ± 9.66 cc (0.27-42.4 cc) in the 50% isodose curve. There was no significant difference between the superficial and deep batches in the phantom studies (P-value < 0.05). The mean delivered doses to the parotid, thyroid, ovaries and testis in human subjects were 21.6 ± 15.1 cGy, 9.15 ± 3.89 cGy, 0.47 ± 0.3 cGy and 0.53 ± 0.31 cGy, respectively. The data can be used in making decisions for special clinical situations such as treating pregnant patients or young patients with benign lesions who need radiosurgery for eradication of brain tumours.

  14. End-to-end test of spatial accuracy in Gamma Knife treatments for trigeminal neuralgia

    SciTech Connect

    Brezovich, Ivan A. Wu, Xingen; Duan, Jun; Popple, Richard A.; Shen, Sui; Benhabib, Sidi; Huang, Mi; Christian Dobelbower, M.; Fisher III, Winfield S.

    2014-11-01

    Purpose: Spatial accuracy is most crucial when small targets like the trigeminal nerve are treated. Although current quality assurance procedures typically verify that individual apparatus, like the MRI scanner, CT scanner, Gamma Knife, etc., are meeting specifications, the cumulative error of all equipment and procedures combined may exceed safe margins. This study uses an end-to-end approach to assess the overall targeting errors that may have occurred in individual patients previously treated for trigeminal neuralgia. Methods: The trigeminal nerve is simulated by a 3 mm long, 3.175 mm (1/8 in.) diameter MRI-contrast filled cavity embedded within a PMMA plastic capsule. The capsule is positioned within the head frame such that the location of the cavity matches the Gamma Knife coordinates of an arbitrarily chosen, previously treated patient. Gafchromic EBT2 film is placed at the center of the cavity in coronal and sagittal orientations. The films are marked with a pinprick to identify the cavity center. Treatments are planned for radiation delivery with 4 mm collimators according to MRI and CT scans using the clinical localizer boxes and acquisition protocols. Shots are planned so that the 50% isodose surface encompasses the cavity. Following irradiation, the films are scanned and analyzed. Targeting errors are defined as the distance between the pinprick, which represents the intended target, and the centroid of the 50% isodose line, which is the center of the radiation field that was actually delivered. Results: Averaged over ten patient simulations, targeting errors along the x, y, and z coordinates (patient’s left-to-right, posterior-to-anterior, and head-to-foot) were, respectively, −0.060 ± 0.363, −0.350 ± 0.253, and 0.348 ± 0.204 mm when MRI was used for treatment planning. Planning according to CT exhibited generally smaller errors, namely, 0.109 ± 0.167, −0.191 ± 0.144, and 0.211 ± 0.094 mm. The largest errors along individual axes in MRI

  15. SU-E-T-605: A New Design for a Rotating Gamma Knife. Monte Carlo Simulation

    SciTech Connect

    Mora, G; Chibani, O; Li, J; Ma, C

    2014-06-01

    Purpose: to determine the characteristics of the 60Co beam emerging from a new design of a rotating Gamma Knife system and to calculate 3D dose distributions at the isocenter for different source configurations and collimator openings. Methods: We employed the BEAM-Monte Carlo code to realistically model the geometry design, including 30 60Co source capsules, two circular primary collimators (diameter of 6.6mm and 6.1mm) and four different changeable collimators. The shielding of the head design was also simulated. The sources (2.8mm diameter) are distributed in six groups in the spherical geometry. Each source is individually collimated to obtained four different circular fields at the isocenter (3mm, 3.5mm, 6mm and 8mm).The phase-space particles reaching the scoring plane below the primary collimation assembly were recorded and the BEAMDP code was used to determine the fluence and energy spectra of the particles emerging from each source-collimator configuration. The dose distributions at the isocenter plane (397.6mm from the source) were calculated in a spherical component module for the circular field sizes studied. Results: The energy spectra below the head assembly and primary collimators have been obtained, which exhibited the typical 60Co peaks and a small low-energy tail due to scattered photons (from about 200keV to 1MeV). The scattered component of the spectra represents about 8 % of the total number of photons reaching the scoring plane. The radial photon fluence does not vary significantly inside the collimator openings. The spectra of particles from different source groups are compared. Conclusion: The 60Co beam emerging from each source configuration was characterized, which can be used to establish a generic source model for all the sources for fast MC dose calculation. Further investigations are needed to determine the dose variations as a result of partial switching on/off different groups of sources for advanced Gamma Knife SRS/SBRT planning.

  16. Impact of Millimeter-Level Margins on Peripheral Normal Brain Sparing for Gamma Knife Radiosurgery

    SciTech Connect

    Ma, Lijun; Sahgal, Arjun; Larson, David A.; Pinnaduwage, Dilini; Fogh, Shannon; Barani, Igor; Nakamura, Jean; McDermott, Michael; Sneed, Penny

    2014-05-01

    Purpose: To investigate how millimeter-level margins beyond the gross tumor volume (GTV) impact peripheral normal brain tissue sparing for Gamma Knife radiosurgery. Methods and Materials: A mathematical formula was derived to predict the peripheral isodose volume, such as the 12-Gy isodose volume, with increasing margins by millimeters. The empirical parameters of the formula were derived from a cohort of brain tumor and surgical tumor resection cavity cases (n=15) treated with the Gamma Knife Perfexion. This was done by first adding margins from 0.5 to 3.0 mm to each individual target and then creating for each expanded target a series of treatment plans of nearly identical quality as the original plan. Finally, the formula was integrated with a published logistic regression model to estimate the treatment-induced complication rate for stereotactic radiosurgery when millimeter-level margins are added. Results: Confirmatory correlation between the nominal target radius (ie, R{sub T}) and commonly used maximum target size was found for the studied cases, except for a few outliers. The peripheral isodose volume such as the 12-Gy volume was found to increase exponentially with increasing Δ/R{sub T}, where Δ is the margin size. Such a curve fitted the data (logarithmic regression, R{sup 2} >0.99), and the 12-Gy isodose volume was shown to increase steeply with a 0.5- to 3.0-mm margin applied to a target. For example, a 2-mm margin on average resulted in an increase of 55% ± 16% in the 12-Gy volume; this corresponded to an increase in the symptomatic necrosis rate of 6% to 25%, depending on the Δ/R{sub T} values for the target. Conclusions: Millimeter-level margins beyond the GTV significantly impact peripheral normal brain sparing and should be applied with caution. Our model provides a rapid estimate of such an effect, particularly for large and/or irregularly shaped targets.

  17. Gamma Knife Treatment of Growing Vestibular Schwannoma in Norway: A Prospective Study

    SciTech Connect

    Varughese, Jobin Kotakkathu; Wentzel-Larsen, Tore; Pedersen, Paal-Henning; Mahesparan, Ruby; Lund-Johansen, Morten

    2012-10-01

    Purpose: Gamma Knife radiosurgery (GKRS) has been increasingly used in the treatment of vestibular schwannoma (VS). Very few studies relate tumor control and post-treatment growth rates to pretreatment growth rates. Methods and Materials: We prospectively included 45 consecutive VS patients who were initially treated conservatively and then received GKRS between 2000 and 2007 because of demonstrated tumor growth. Pretreatment and post-treatment tumor volumes were estimated. Patients underwent audiograms, reported their symptoms, and responded to the Short Form General Health Survey (SF-36) questionnaire on each visit. Results: Volume doubling times before and after treatment were 1.36 years (95% confidence intervals, 1.14-1.68) and -13.1 years (95% confidence intervals, -111.0 to -6.94), respectively. Tumor control, defined as a post-GKRS growth rate {<=}0, was achieved in 71.1% of patients, with highest odds for tumor control among older patients and those with larger tumors. The 5-year retreatment-free survival rate was 93.9% (95% confidence intervals, 76.5-98.5). None of the clinical endpoints investigated showed statistically significant changes after GKRS, but improvement was seen in a few SF-36 parameters. Conclusions: GKRS alters the natural course of the tumor by reducing growth. Mathematic models yield poorer tumor control rates than those found by clinical assessment. Symptoms were unaffected by treatment, but quality of life was improved.

  18. Brain Edema after Repeat Gamma Knife Radiosurgery for a Large Arteriovenous Malformation: A Case Report

    PubMed Central

    Kim, Joo Whan; Chung, Hyun-Tai; Han, Moon Hee; Kim, Dong Gyu

    2016-01-01

    Brain edema due to venous thrombosis following stereotactic radiosurgery for a cerebral arteriovenous malformation (AVM) has rarely been reported. We report a patient with a large AVM in the eloquent area, and brain edema developed in this area after repeat Gamma knife stereotactic radiosurgery (GKRS). An 18-year-old female presented with a 4-year-history of persistent headache. Magnetic resonance imaging and transfemoral carotid angiogram revealed a high-flow large AVM in the left parieto-occipital area. Brain edema developed and aggravated patient's symptoms after time-staged GKRS. The cause of edema was thought to be the failure of the surrounding venous channels to drain the venous flow from the normal brain and the drainage was hampered by the persistent shunt flow from the AVM, which was due to the thrombosis of one huge draining vein of the AVM. The microsurgical resection of the AVM nidus eliminated shunt flow and completely normalized the brain edema. Microsurgical resection of the AVM nidus completely normalized the brain edema due to thrombosis of a draining vein of an AVM develops after SRS. PMID:27574486

  19. Effect of beam channel plugging on the outcome of gamma knife radiosurgery for trigeminal neuralgia

    SciTech Connect

    Massager, Nicolas . E-mail: nmassage@ulb.ac.be; Nissim, Ouzi; Murata, Noriko; Devriendt, Daniel; Desmedt, Francoise; Vanderlinden, Bruno; Regis, Jean; Levivier, Marc

    2006-07-15

    Purpose: We studied the influence of using plugs for brainstem protection during gamma knife radiosurgery (GKR) of trigeminal neuralgia (TN), with special emphasis on irradiation doses delivered to the trigeminal nerve, pain outcomes, and incidence of trigeminal dysfunction. Methods and Materials: A GKR procedure for TN using an anterior cisternal target and a maximum dose of 90 Gy was performed in 109 patients. For 49 patients, customized beam channel blocking (plugs) were used to reduce the dose delivered to the brainstem. We measured the mean and integrated radiation doses delivered to the trigeminal nerve and the clinical course of patients treated with and without plugs. Results: We found that blocking increases the length of trigeminal nerve exposed to high-dose radiation, resulting in a significantly higher mean dose to the trigeminal nerve. Significantly more of the patients with blocking achieved excellent pain outcomes (84% vs. 62%), but with higher incidences of moderate and bothersome trigeminal nerve dysfunction (37% mild/10% bothersome with plugs vs. 30% mild/2% bothersome without). Conclusions: The use of plugs to protect the brainstem during GKR treatment for TN increases the dose of irradiation delivered to the intracisternal trigeminal nerve root and is associated with an important increase in the incidence of trigeminal nerve dysfunction. Therefore, beam channel blocking should be avoided for 90 Gy-GKR of TN.

  20. Gamma knife radiosurgery of craniopharyngioma: results of 30 cases treated at Nagoya Radiosurgery Center

    PubMed Central

    Kobayashi, Tatsuya; Tsugawa, Takahiko; Hatano, Manabu; Hashizume, Chisa; Mori, Yoshimasa; Shibamoto, Yuta

    2015-01-01

    ABSTRACT Evaluation of 30 cases of craniopharyngioma treated by Gamma Knife at Nagoya Radiosurgery Center (NRC), Nagoya Kyoritsu Hospital since July, 2004 has been made. The mean volume of the tumor was 2.64 ml, which was treated with the marginal dose of 11.7 Gy. Mean follow-up period was 79.9 months. The effects were evaluated by MRI findings, neuro-endocrine and hypothalamic signs and symptoms, complications and KPS every 3~6 months. As the results, complete remission was obtained in 8, partial remission in 12, no change in 6, progression in 3, in which two died by hypothalamic invasion. Tumor response rate was 68.9% and control rate 87.9%. Actuarial survival was 96% at 5 and 86% at 10 years. However, progression free survival was 76% and 76%, respectively. Using marginal dose of 11.7Gy to a smaller tumor, better control without complications has been obtained. KPS was excellent in 14, good in 9, fair in 2, poor in 1 and unknown in a case. Finally, there were three deaths, where two were died of tumor progression and one by infirmity. The progression of hypothalamic symptoms other than diabetes insipidus were found in two cases. Volume reduction and effective dose setting will be important for the improvement of QOL and survival after combined microsurgery and radiosurgery of craniopharyngioma. PMID:26412891

  1. First year experience with newly developed Leksell Gamma Knife® Perfexion™

    PubMed Central

    Bhatnagar, Jagdish P.; Novotny, Josef; Niranjan, Ajay; Kondziolka1, Douglas; Flickinger, John; Lunsford, Dade; Huq, M. Saiful

    2009-01-01

    A new model of Leksell Gamma Knife® (LGK), known as Perfexion™ (LGK PFX), was introduced by Elekta Instrument, AB, Sweden, in 2006. This model has a radically different design from the earlier models U, B, C and 4C. Dosimetric characteristics of LGK PFX, technical differences between LGK PFX and LGK 4C, experience gained with acceptance testing and commissioning of the LGK PFX, and comparison between LGK PFX and LGK 4C are presented in this study. Excellent agreement is found between the manufacturers recommended values of absorbed dose rate, relative output factors for 4 and 8 mm collimators, coincidence of mechanical and dosimetric isocenter, FWHM for beam profiles for various collimators and those reported in the present study. Excellent agreement is also found between the dosimetric characteristics of LGK PFX and LGK 4C for the 4 and 8 mm collimators. Examples of clinical cases treated with LGK PFX and impact of LGK PFX on workflow and dosimetric conformity of treatment planning is also given. The set up and treatment of patients on the LGK PFX is much more efficient since it is a fully automated system. The system also provides more options to generate plan with high dosimetric conformity. PMID:20098561

  2. Brain Edema after Repeat Gamma Knife Radiosurgery for a Large Arteriovenous Malformation: A Case Report.

    PubMed

    Kim, Joo Whan; Chung, Hyun-Tai; Han, Moon Hee; Kim, Dong Gyu; Paek, Sun Ha

    2016-08-01

    Brain edema due to venous thrombosis following stereotactic radiosurgery for a cerebral arteriovenous malformation (AVM) has rarely been reported. We report a patient with a large AVM in the eloquent area, and brain edema developed in this area after repeat Gamma knife stereotactic radiosurgery (GKRS). An 18-year-old female presented with a 4-year-history of persistent headache. Magnetic resonance imaging and transfemoral carotid angiogram revealed a high-flow large AVM in the left parieto-occipital area. Brain edema developed and aggravated patient's symptoms after time-staged GKRS. The cause of edema was thought to be the failure of the surrounding venous channels to drain the venous flow from the normal brain and the drainage was hampered by the persistent shunt flow from the AVM, which was due to the thrombosis of one huge draining vein of the AVM. The microsurgical resection of the AVM nidus eliminated shunt flow and completely normalized the brain edema. Microsurgical resection of the AVM nidus completely normalized the brain edema due to thrombosis of a draining vein of an AVM develops after SRS. PMID:27574486

  3. Trigeminal Neuralgia Caused by Cerebellopontine Angle Arteriovenous Malformation Treated With Gamma Knife Radiosurgery.

    PubMed

    Işik, Semra; Ekşi, Murat Şakir; Yilmaz, Baran; Toktaş, Zafer Orkun; Akakin, Akin; Kiliç, Türker

    2016-01-01

    Trigeminal neuralgia is a facial pain syndrome characterized as sudden onset and lightening-like sensation over somatosensorial branch(es) of fifth cranial nerve. Rarely, some underlying diseases or disorders could be diagnosed, such as multiple sclerosis, brain tumors, and vascular malformations. The authors present a 47-year-old man with trigeminal neuralgia over left V2 and V3 dermatomes. He had a previous transarterial embolization and long use of carbamazepine with partial response to treatment. Gamma knife radiosurgery (GKR) was planned. A marginal dose of 15 Gy was given to 50% isodose line. His pain was relieved by GKR in 1.5 years. Treatment of posterior fossa arteriovenous malformations causing trigeminal neuralgia, with GKR has a very limited use in the literature. It, however, is obvious that success rate as pain relief, in a very challenging field of functional neurosurgery, is satisfactory. Large series, however, are in need to make a more comprehensive statement about efficacy and safety of the procedure in these pathologies. PMID:26674920

  4. Determination of the Absorbed Dose Rate to Water for the 18-mm Helmet of a Gamma Knife

    SciTech Connect

    Chung, Hyun-Tai; Park, Youngho; Hyun, Sangil; Choi, Yongsoo; Kim, Gi Hong; Kim, Dong Gyu; Chun, Kook Jin

    2011-04-01

    Purpose: To measure the absorbed dose rate to water of {sup 60}Co gamma rays of a Gamma Knife Model C using water-filled phantoms (WFP). Methods and Materials: Spherical WFP with an equivalent water depth of 5, 7, 8, and 9 cm were constructed. The dose rates at the center of an 18-mm helmet were measured in an 8-cm WFP (WFP-3) and two plastic phantoms. Two independent measurement systems were used: one was calibrated to an air kerma (Set I) and the other was calibrated to the absorbed dose to water (Set II). The dose rates of WFP-3 and the plastic phantoms were converted to dose rates for an 8-cm water depth using the attenuation coefficient and the equivalent water depths. Results: The dose rate measured at the center of WFP-3 using Set II was 2.2% and 1.0% higher than dose rates measured at the center of the two plastic phantoms. The measured effective attenuation coefficient of Gamma Knife photon beam in WFPs was 0.0621 cm{sup -1}. After attenuation correction, the difference between the dose rate at an 8-cm water depth measured in WFP-3 and dose rates in the plastic phantoms was smaller than the uncertainty of the measurements. Conclusions: Systematic errors related to the characteristics of the phantom materials in the dose rate measurement of a Gamma Knife need to be corrected for. Correction of the dose rate using an equivalent water depth and attenuation provided results that were more consistent.

  5. Gamma Knife radiosurgery of olfactory groove meningiomas provides a method to preserve subjective olfactory function.

    PubMed

    Gande, Abhiram; Kano, Hideyuki; Bowden, Gregory; Mousavi, Seyed H; Niranjan, Ajay; Flickinger, John C; Lunsford, L Dade

    2014-02-01

    Anosmia is a common outcome after resection of olfactory groove meningioma(s) (OGM) and for some patients represents a significant disability. To evaluate long term tumor control rates and preservation of subjective olfaction after Gamma Knife (GK) stereotactic radiosurgery (SRS) of OGM. We performed a retrospective chart review and telephone assessments of 41 patients who underwent GK SRS between 1987 and 2008. Clinical outcomes were stratified by full, partial or no subjective olfaction, whereas tumor control was assessed by changes in volume greater or lesser than 25%. The median clinical and imaging follow-up were 76 and 65 months, respectively. Prior to SRS, 19 (46%) patients had surgical resections and two (5%) had received fractionated radiation therapy. Twenty four patients (59%) reported a normal sense of smell, 12 (29%) reported a reduced sense of smell and five (12%) had complete anosmia. The median tumor volume was 8.5 cm(3) (range 0.6-56.1), the mean radiation dose at the tumor margin was 13 Gy (range 10-20) and the median estimated dose to the olfactory nerve was 5.1 Gy (range 1.1-18.1). At follow-up, 27 patients (66%) reported intact olfaction (three (7%) described return to a normal sense of smell), nine (22%) described partial anosmia, and five (12%) had complete anosmia. No patient reported deterioration in olfaction after SRS. Thirteen patients (32%) showed significant tumor regression, 26 (63%) had no further growth and two (5%) had progressed. The progression free tumor control rates were 97% at 1 year and 95% at 2, 10 and 20 years. Symptomatic adverse radiation effects occurred in three (7%) patients. Stereotactic radiosurgery provided both long term tumor control and preservation of olfaction. PMID:24398616

  6. Clinical Realization of Sector Beam Intensity Modulation for Gamma Knife Radiosurgery: A Pilot Treatment Planning Study

    SciTech Connect

    Ma, Lijun; Mason, Erica; Sneed, Penny K.; McDermott, Michael; Polishchuk, Alexei; Larson, David A.; Sahgal, Arjun

    2015-03-01

    Purpose: To demonstrate the clinical feasibility and potential benefits of sector beam intensity modulation (SBIM) specific to Gamma Knife stereotactic radiosurgery (GKSRS). Methods and Materials: SBIM is based on modulating the confocal beam intensities from individual sectors surrounding an isocenter in a nearly 2π geometry. This is in contrast to conventional GKSRS delivery, in which the beam intensities from each sector are restricted to be either 0% or 100% and must be identical for any given isocenter. We developed a SBIM solution based on available clinical planning tools, and we tested it on a cohort of 12 clinical cases as a proof of concept study. The SBIM treatment plans were compared with the original clinically delivered treatment plans to determine dosimetric differences. The goal was to investigate whether SBIM would improve the dose conformity for these treatment plans without prohibitively lengthening the treatment time. Results: A SBIM technique was developed. On average, SBIM improved the Paddick conformity index (PCI) versus the clinically delivered plans (clinical plan PCI = 0.68 ± 0.11 vs SBIM plan PCI = 0.74 ± 0.10, P=.002; 2-tailed paired t test). The SBIM plans also resulted in nearly identical target volume coverage (mean, 97 ± 2%), total beam-on times (clinical plan 58.4 ± 38.9 minutes vs SBIM 63.5 ± 44.7 minutes, P=.057), and gradient indices (clinical plan 3.03 ± 0.27 vs SBIM 3.06 ± 0.29, P=.44) versus the original clinical plans. Conclusion: The SBIM method is clinically feasible with potential dosimetric gains when compared with conventional GKSRS.

  7. Anatomic Landmarks Versus Fiducials for Volume-Staged Gamma Knife Radiosurgery for Large Arteriovenous Malformations

    SciTech Connect

    Petti, Paula L. . E-mail: ppetti@radonc.ucsf.edu; Coleman, Joy; McDermott, Michael; Smith, Vernon; Larson, David A.

    2007-04-01

    Purpose: The purpose of this investigation was to compare the accuracy of using internal anatomic landmarks instead of surgically implanted fiducials in the image registration process for volume-staged gamma knife (GK) radiosurgery for large arteriovenous malformations. Methods and Materials: We studied 9 patients who had undergone 10 staged GK sessions for large arteriovenous malformations. Each patient had fiducials surgically implanted in the outer table of the skull at the first GK treatment. These markers were imaged on orthogonal radiographs, which were scanned into the GK planning system. For the same patients, 8-10 pairs of internal landmarks were retrospectively identified on the three-dimensional time-of-flight magnetic resonance imaging studies that had been obtained for treatment. The coordinate transformation between the stereotactic frame space for subsequent treatment sessions was then determined by point matching, using four surgically embedded fiducials and then using four pairs of internal anatomic landmarks. In both cases, the transformation was ascertained by minimizing the chi-square difference between the actual and the transformed coordinates. Both transformations were then evaluated using the remaining four to six pairs of internal landmarks as the test points. Results: Averaged over all treatment sessions, the root mean square discrepancy between the coordinates of the transformed and actual test points was 1.2 {+-} 0.2 mm using internal landmarks and 1.7 {+-} 0.4 mm using the surgically implanted fiducials. Conclusion: The results of this study have shown that using internal landmarks to determine the coordinate transformation between subsequent magnetic resonance imaging scans for volume-staged GK arteriovenous malformation treatment sessions is as accurate as using surgically implanted fiducials and avoids an invasive procedure.

  8. Gamma Knife Radiosurgery for Benign Tumors With Symptoms From Brainstem Compression

    SciTech Connect

    Nakaya, Kotaro; Niranjan, Ajay; Kondziolka, Douglas

    2010-07-15

    Purpose: This study evaluated the role of radiosurgery in the management of symptomatic patients with brainstem compression from benign basal tumors. Methods and Materials: Over a 17-year, period 246 patients (202 vestibular schwannomas and 44 meningiomas) with brainstem compression from benign skull-base tumors were managed with Gamma Knife radiosurgery. Median tumor volumes were 3.9 cm{sup 3} (range, 0.8-39.0 mL) and 6.6 mL (range, 1.6-25.1 mL) for vestibular schwannomas and meningiomas, respectively. For both tumors, a median marginal dose of 13 Gy was prescribed. Median follow-up of patients was 65 months for vestibular schwannomas and 60 months for meningiomas. Patients were categorized into four groups on the basis of the tumor-brainstem relationship on neuroimaging. Results: Preservation of function was stratified according to grade of brainstem compression. We analyzed the effect of radiosurgery on symptoms of brainstem compression. The tumor control rate was 100 % for meningioma and 97% for vestibular schwannomas (although 5% required an additional procedure such as a ventriculoperitoneal shunt). In patients with vestibular schwannoma, serviceable hearing was preserved in 72.0%. Balance improved in 31.9%, remained unchanged in 56.5%, and deteriorated in 11.6% of patients who had imbalance at presentation. Balance improved significantly in patients who had less tumor compression (p = 0.0357) after radiosurgery. Symptoms improved in 43.2% of patients with meningioma. Conclusion: Radiosurgery is a minimally invasive option for patients with benign basal tumors that indent or distort the brainstem. A high tumor growth control rate and satisfactory rate of neurological preservation and symptom control can be obtained with radiosurgery.

  9. Hearing Preservation after Low-dose Gamma Knife Radiosurgery of Vestibular Schwannomas

    PubMed Central

    HORIBA, Ayako; HAYASHI, Motohiro; CHERNOV, Mikhail; KAWAMATA, Takakazu; OKADA, Yoshikazu

    2016-01-01

    The objective of the retrospective study was to evaluate the factors associated with hearing preservation after low-dose Gamma Knife radiosurgery (GKS) of vestibular schwannomas performed according to the modern standards. From January 2005 to September 2010, 141 consecutive patients underwent such treatment in Tokyo Women’s Medical University. Mean marginal dose was 11.9 Gy (range, 11–12 Gy). The doses for the brain stem, cranial nerves (V, VII, and VIII), and cochlea were kept below 14 Gy, 12 Gy, and 4 Gy, respectively. Out of the total cohort, 102 cases with at least 24 months follow-up were analyzed. Within the median follow-up of 56 months (range, 24–99 months) the crude tumor growth control was 92% (94 cases), whereas its actuarial rate at 5 years was 93%. Out of 49 patients with serviceable hearing on the side of the tumor before GKS, 28 (57%) demonstrated its preservation at the time of the last follow-up. No one evaluated factor, namely Gardner-Robertson hearing class before irradiation, Koos tumor stage, extension of the intrameatal part of the neoplasm up to fundus, nerve of tumor origin, presence of cystic changes in the neoplasm, and cochlea dose demonstrated statistically significant association with preservation of the serviceable hearing after radiosurgery. In conclusion, GKS of vestibular schwannomas performed according to the modern standards of treatment permits to preserve serviceable hearing on the side of the tumor in more than half of the patients. The actual causes of hearing deterioration after radiosurgery remain unclear. PMID:26876903

  10. Long-Term Outcome of Gamma Knife Radiosurgery for Treatment of Typical Trigeminal Neuralgia

    SciTech Connect

    Han, Jung Ho; Kim, Dong Gyu; Chung, Hyun-Tai; Paek, Sun Ha; Kim, Yong Hwy; Kim, Chae-Yong; Kim, Jin Wook; Kim, Young-Hoon; Jeong, Sang Soon

    2009-11-01

    Purpose: To analyze the long-term outcomes of patients with typical trigeminal neuralgia treated with gamma knife radiosurgery (GKRS). Patients and Methods: A total of 62 consecutive patients with typical trigeminal neuralgia were treated with GKRS between 1998 and 2004. Of the 62 patients, 2 were lost to follow-up; the remaining 60 patients were followed for >12 months. The mean prescribed maximal dose was 79.7 Gy (range, 75-80), using a 4-mm shot. Results: Of the 60 patients, 48 were followed for >4 years. An additional 3 patients, followed for <4 years, experienced recurrent pain after a favorable initial response and were incorporated into the long-term response analysis. Of these 51 patients (mean age, 61 +- 11 years; 37 women [72.5%]; and mean follow-up duration, 58 +- 14 months), 46 (90.2%) responded to GKRS, as demonstrated by an improvement in their Barrow Neurological Institute pain intensity score. Of the 46 patients, 24 (52.2%) had pain recurrence. The actuarial recurrence-free survival rate was 84.8%, 76.1%, 69.6%, 63.0%, and 45.8% at 1, 2, 3, 4, and 5 years after radiosurgery, respectively. Patient age >70 years correlated with a favorable outcome in terms of pain recurrence after radiosurgery (hazard ratio, 0.125; 95% confidence interval, 0.016-0.975; p = .047) on multivariate analysis. Conclusion: GKRS seems to be an effective treatment modality for patients with typical trigeminal neuralgia considering the initial response rate; however, fewer than one-half of patients might continue to benefit from GKRS after long-term follow-up. Elderly patients might be good candidates for radiosurgery considering the long-term durability of efficacy.

  11. Evaluation of Different Score Index for Predicting Prognosis in Gamma Knife Radiosurgical Treatment for Brain Metastasis

    SciTech Connect

    Franzin, Alberto Snider, Silvia; Picozzi, Piero; Bolognesi, Angelo; Serra, Carlo; Vimercati, Alberto; Passarin, Olga; Mortini, Pietro

    2009-07-01

    Purpose: To assess the utility of the Radiation Therapy Oncology Group Recursive Partitioning Analysis (RPA) and Score Index for Radiosurgery (SIR) stratification systems in predicting survival in patients with brain metastasis treated with Gamma Knife radiosurgery (GKRS). Methods and Materials: A total of 185 patients were included in the study. Patients were stratified according to RPA and SIR classes. The RPA and SIR classes, age, Karnofsky Performance Status (KPS), and systemic disease were correlated with survival. Results: Five patients were lost to follow-up. Median survival in patients in RPA Class 1 (30 patients) was 17 months; in Class 2 (140 patients), 10 months; and in Class 3 (10 patients), 3 months. Median survival in patients in SIR Class 1 (30 patients) was 3 months; in Class 2 (135 patients), 8 months; and in Class 3 (15 patients), 20 months. In univariate testing, age younger than 65 years (p = 0.0004), KPS higher than 70 (p = 0.0001), RPA class (p = 0.0078), SIR class (p = 0.0002), and control of the primary tumor (p = 0.02) were significantly associated with improved outcome. In multivariate analysis, KPS (p < 0.0001), SIR class (p = 0.0008), and RPA class (p = 0.03) had statistical value. Conclusions: This study supports the use of GKRS as a single-treatment modality in this selected group of patients. Stratification systems are useful in the estimation of patient eligibility for GKRS. A second-line treatment was necessary in 30% of patients to achieve distal or local brain control. This strategy is useful to control brain metastasis in long-surviving patients.

  12. Hearing Preservation after Low-dose Gamma Knife Radiosurgery of Vestibular Schwannomas.

    PubMed

    Horiba, Ayako; Hayashi, Motohiro; Chernov, Mikhail; Kawamata, Takakazu; Okada, Yoshikazu

    2016-04-15

    The objective of the retrospective study was to evaluate the factors associated with hearing preservation after low-dose Gamma Knife radiosurgery (GKS) of vestibular schwannomas performed according to the modern standards. From January 2005 to September 2010, 141 consecutive patients underwent such treatment in Tokyo Women's Medical University. Mean marginal dose was 11.9 Gy (range, 11-12 Gy). The doses for the brain stem, cranial nerves (V, VII, and VIII), and cochlea were kept below 14 Gy, 12 Gy, and 4 Gy, respectively. Out of the total cohort, 102 cases with at least 24 months follow-up were analyzed. Within the median follow-up of 56 months (range, 24-99 months) the crude tumor growth control was 92% (94 cases), whereas its actuarial rate at 5 years was 93%. Out of 49 patients with serviceable hearing on the side of the tumor before GKS, 28 (57%) demonstrated its preservation at the time of the last follow-up. No one evaluated factor, namely Gardner-Robertson hearing class before irradiation, Koos tumor stage, extension of the intrameatal part of the neoplasm up to fundus, nerve of tumor origin, presence of cystic changes in the neoplasm, and cochlea dose demonstrated statistically significant association with preservation of the serviceable hearing after radiosurgery. In conclusion, GKS of vestibular schwannomas performed according to the modern standards of treatment permits to preserve serviceable hearing on the side of the tumor in more than half of the patients. The actual causes of hearing deterioration after radiosurgery remain unclear. PMID:26876903

  13. Tolerance of Pyramidal Tract to Gamma Knife Radiosurgery Based on Diffusion-Tensor Tractography

    SciTech Connect

    Maruyama, Keisuke Kamada, Kyousuke; Ota, Takahiro; Koga, Tomoyuki; Itoh, Daisuke; Ino, Kenji R.T.; Aoki, Shigeki; Tago, Masao; Masutani, Yoshitaka; Shin, Masahiro; Saito, Nobuhito

    2008-04-01

    Purpose: To minimize the morbidity of radiosurgery for critically located lesions, we integrated diffusion-tensor tractography into treatment planning for gamma-knife radiosurgery. We calculated the refined tolerance of the pyramidal tract (PT) after prospective application of the technique to additional patients. Methods and Materials: The relationship between the dosimetry during treatment planning and the development of subsequent motor complications was investigated in 24 patients, 9 studied retrospectively and 15 studied prospectively. The maximal dose to the PT and the volumes of the PT that received {>=}20 Gy (20-Gy volume) and {>=}25 Gy (25-Gy volume) were calculated. Univariate logistic regression analyses were used to produce dose-response curves. Differences in the tolerable dose according to the PT location were calculated. Results: Univariate logistic regression analysis of the motor complications revealed a significant independent correlation with the maximal dose to the PT and the 20- and 25-Gy volumes. The maximal dose to the PT with a 5% risk of motor complications was 23 Gy compared with 15 Gy in our previous report. The risk of motor complications was significantly greater in the internal capsule than in the corona radiata for the 20- and 25-Gy volumes in generalized Wilcoxon tests (p = 0.031), although no significant difference was observed for the maximal dose. Conclusion: The tolerable dose of the PT was greater than that previously reported. The internal capsule was more sensitive to high-dose irradiation over a wide area of the PT, probably owing to the dense concentration of motor fibers.

  14. SU-E-T-104: Development of 3 Dimensional Dosimetry System for Gamma Knife

    SciTech Connect

    Yoon, K; Kwak, J; Cho, B; Lee, D; Ahn, S

    2014-06-01

    Purpose: The aim of this study was to develop a new 3 dimensional dosimetry system to verify the dosimetric accuracy of Leksell Gamma Knife-Perfexion™ (LGK) (Elekta, Norcross, GA). Methods: We designed and manufactured a lightweight dosimetry instrument to be equipped with the head frame to LGK. It consists of a head phantom, a scintillator, a CCD camera and a step motor. The 10×10 cm2 sheet of Gd2O3;Tb phosphor or Gafchromic EBT3 film was located at the center of the 16 cm diameter hemispherical PMMA, the head phantom. The additional backscatter compensating material of 1 cm thick PMMA plate was placed downstream of the phosphor sheet. The backscatter plate was transparent for scintillation lights to reach the CCD camera with 1200×1200 pixels by 5.2 um pitch. With This equipment, 300 images with 0.2 mm of slice gap were acquired under three collimator setups (4mm, 8mm and 16mm), respectively. The 2D projected doses from 3D distributions were compared with the exposured film dose. Results: As all doses normalized by the maximum dose value in 16 mm setup, the relative differences between the equipment dose and film dose were 0.2% for 4mm collimator and 0.5% for 8mm. The acquisition of 300 images by the equipment took less than 3 minutes. Conclusion: The new equipment was verified to be a good substitute to radiochromic film, with which required more time and resources. Especially, the new methods was considered to provide much convenient and faster solution in the 3D dose acquisition for LGK.

  15. Percutaneous transluminal angioplasty in a patient with internal carotid artery stenosis following gamma knife radiosurgery for recurrent pituitary adenoma

    PubMed Central

    Ito, Hidemichi; Onodera, Hidetaka; Sase, Taigen; Uchida, Masashi; Morishima, Hiroyuki; Oshio, Kotaro; Shuto, Takashi; Tanaka, Yuichiro

    2015-01-01

    Background: Intracranial vascular complications following radiosurgery are extremely rare. Case Description: We report a case of stenosis in the internal carotid artery 5 years after gamma knife radiosurgery for a recurrent pituitary adenoma. Percutaneous transluminal angioplasty was performed successfully with anatomical and functional improvement. Conclusion: These results suggested the importance of monitoring for arterial stenosis in the long-term follow-up. Moreover, this is the first case of endovascular treatment as an effective therapy for intracranial arterial stenosis due to radiotherapy. PMID:26069850

  16. Stereotactic radiosurgery versus stereotactic radiotherapy for patients with vestibular schwannoma: a Leksell Gamma Knife Society 2000 debate.

    PubMed

    Linskey, Mark E

    2013-12-01

    By definition, the term "radiosurgery" refers to the delivery of a therapeutic radiation dose in a single fraction, not simply the use of stereotaxy. Multiple-fraction delivery is better termed "stereotactic radiotherapy." There are compelling radiobiological principles supporting the biological superiority of single-fraction radiation for achieving an optimal therapeutic response for the slowly proliferating, late-responding, tissue of a schwannoma. It is axiomatic that complication avoidance requires precise three-dimensional conformality between treatment and tumor volumes. This degree of conformality can only be achieved through complex multiisocenter planning. Alternative radiosurgery devices are generally limited to delivering one to four isocenters in a single treatment session. Although they can reproduce dose plans similar in conformality to early gamma knife dose plans by using a similar number of isocenters, they cannot reproduce the conformality of modern gamma knife plans based on magnetic resonance image--targeted localization and five to 30 isocenters. A disturbing trend is developing in which institutions without nongamma knife radiosurgery (GKS) centers are championing and/or shifting to hypofractionated stereotactic radiotherapy for vestibular schwannomas. This trend appears to be driven by a desire to reduce complication rates to compete with modern GKS results by using complex multiisocenter planning. Aggressive advertising and marketing from some of these centers even paradoxically suggests biological superiority of hypofractionation approaches over single-dose radiosurgery for vestibular schwannomas. At the same time these centers continue to use the term radiosurgery to describe their hypofractionated radiotherapy approach in an apparent effort to benefit from a GKS "halo effect." It must be reemphasized that as neurosurgeons our primary duty is to achieve permanent tumor control for our patients and not to eliminate complications at the

  17. Three-dimensional dose verification of the clinical application of gamma knife stereotactic radiosurgery using polymer gel and MRI

    NASA Astrophysics Data System (ADS)

    Papagiannis, P.; Karaiskos, P.; Kozicki, M.; Rosiak, J. M.; Sakelliou, L.; Sandilos, P.; Seimenis, I.; Torrens, M.

    2005-05-01

    This work seeks to verify multi-shot clinical applications of stereotactic radiosurgery with a Leksell Gamma Knife model C unit employing a polymer gel-MRI based experimental procedure, which has already been shown to be capable of verifying the precision and accuracy of dose delivery in single-shot gamma knife applications. The treatment plan studied in the present work resembles a clinical treatment case of pituitary adenoma using four 8 mm and one 14 mm collimator helmet shots to deliver a prescription dose of 15 Gy to the 50% isodose line (30 Gy maximum dose). For the experimental dose verification of the treatment plan, the same criteria as those used in the clinical treatment planning evaluation were employed. These included comparison of measured and GammaPlan calculated data, in terms of percentage isodose contours on axial, coronal and sagittal planes, as well as 3D plan evaluation criteria such as dose-volume histograms for the target volume, target coverage and conformity indices. Measured percentage isodose contours compared favourably with calculated ones despite individual point fluctuations at low dose contours (e.g., 20%) mainly due to the effect of T2 measurement uncertainty on dose resolution. Dose-volume histogram data were also found in a good agreement while the experimental results for the percentage target coverage and conformity index were 94% and 1.17 relative to corresponding GammaPlan calculations of 96% and 1.12, respectively. Overall, polymer gel results verified the planned dose distribution within experimental uncertainties and uncertainty related to the digitization process of selected GammaPlan output data.

  18. Gamma-knife radiosurgery in acromegaly: a 4-year follow-up study.

    PubMed

    Attanasio, Roberto; Epaminonda, Paolo; Motti, Enrico; Giugni, Enrico; Ventrella, Laura; Cozzi, Renato; Farabola, Mario; Loli, Paola; Beck-Peccoz, Paolo; Arosio, Maura

    2003-07-01

    Stereotactic radiosurgery by gamma-knife (GK) is an attractive therapeutic option after failure of microsurgical removal in patients with pituitary adenoma. In these tumors or remnants of them, it aims to obtain the arrest of cell proliferation and hormone hypersecretion using a single precise high dose of ionizing radiation, sparing surrounding structures. The long-term efficacy and toxicity of GK in acromegaly are only partially known. Thirty acromegalic patients (14 women and 16 men) entered a prospective study of GK treatment. Most were surgical failures, whereas in 3 GK was the primary treatment. Imaging of the adenoma and target coordinates identification were obtained by high resolution magnetic resonance imaging. All patients were treated with multiple isocenters (mean, 8; range, 3-11). The 50% isodose was used in 27 patients (90%). The mean margin dose was 20 Gy (range, 15-35), and the dose to the visual pathways was always less than 8 Gy. After a median follow-up of 46 months (range, 9-96), IGF-I fell from 805 micro g/liter (median; interquartile range, 640-994) to 460 micro g/liter (interquartile range, 217-654; P = 0.0002), and normal age-matched IGF-I levels were reached in 7 patients (23%). Mean GH levels decreased from 10 micro g/liter (interquartile range, 6.4-15) to 2.9 micro g/liter (interquartile range, 2-5.3; P < 0.0001), reaching levels below 2.5 micro g/liter in 11 (37%). The rate of persistently pathological hormonal levels was still 70% at 5 yr by Kaplan-Meier analysis. The median volume was 1.43 ml (range, 0.20-3.7). Tumor shrinkage (at least 25% of basal volume) occurred after 24 months (range, 12-36) in 11 of 19 patients (58% of assessable patients). The rate of shrinkage was 79% at 4 yr. In no case was further growth observed. Only 1 patient complained of side-effects (severe headache and nausea immediately after the procedure, with full recovery in a few days with steroid therapy). Anterior pituitary failures were observed in 2 patients

  19. On the development of a comprehensive MC simulation model for the Gamma Knife Perfexion radiosurgery unit

    NASA Astrophysics Data System (ADS)

    Pappas, E. P.; Moutsatsos, A.; Pantelis, E.; Zoros, E.; Georgiou, E.; Torrens, M.; Karaiskos, P.

    2016-02-01

    This work presents a comprehensive Monte Carlo (MC) simulation model for the Gamma Knife Perfexion (PFX) radiosurgery unit. Model-based dosimetry calculations were benchmarked in terms of relative dose profiles (RDPs) and output factors (OFs), against corresponding EBT2 measurements. To reduce the rather prolonged computational time associated with the comprehensive PFX model MC simulations, two approximations were explored and evaluated on the grounds of dosimetric accuracy. The first consists in directional biasing of the 60Co photon emission while the second refers to the implementation of simplified source geometric models. The effect of the dose scoring volume dimensions in OF calculations accuracy was also explored. RDP calculations for the comprehensive PFX model were found to be in agreement with corresponding EBT2 measurements. Output factors of 0.819  ±  0.004 and 0.8941  ±  0.0013 were calculated for the 4 mm and 8 mm collimator, respectively, which agree, within uncertainties, with corresponding EBT2 measurements and published experimental data. Volume averaging was found to affect OF results by more than 0.3% for scoring volume radii greater than 0.5 mm and 1.4 mm for the 4 mm and 8 mm collimators, respectively. Directional biasing of photon emission resulted in a time efficiency gain factor of up to 210 with respect to the isotropic photon emission. Although no considerable effect on relative dose profiles was detected, directional biasing led to OF overestimations which were more pronounced for the 4 mm collimator and increased with decreasing emission cone half-angle, reaching up to 6% for a 5° angle. Implementation of simplified source models revealed that omitting the sources’ stainless steel capsule significantly affects both OF results and relative dose profiles, while the aluminum-based bushing did not exhibit considerable dosimetric effect. In conclusion, the results of this work suggest that any PFX

  20. Assessment and characterization of the total geometric uncertainty in Gamma Knife radiosurgery using polymer gels

    SciTech Connect

    Moutsatsos, A.; Karaiskos, P.; Pantelis, E.; Georgiou, E.; Petrokokkinos, L.; Sakelliou, L.; Torrens, M.; Seimenis, I.

    2013-03-15

    Purpose: This work proposes and implements an experimental methodology, based on polymer gels, for assessing the total geometric uncertainty and characterizing its contributors in Gamma Knife (GK) radiosurgery. Methods: A treatment plan consisting of 26, 4-mm GK single shot dose distributions, covering an extended region of the Leksell stereotactic space, was prepared and delivered to a polymer gel filled polymethyl methacrylate (PMMA) head phantom (16 cm diameter) used to accurately reproduce every link in the GK treatment chain. The center of each shot served as a 'control point' in the assessment of the GK total geometric uncertainty, which depends on (a) the spatial dose delivery uncertainty of the PERFEXION GK unit used in this work, (b) the spatial distortions inherent in MR images commonly used for target delineation, and (c) the geometric uncertainty contributor associated with the image registration procedure performed by the Leksell GammaPlan (LGP) treatment planning system (TPS), in the case that registration is directly based on the apparent fiducial locations depicted in each MR image by the N-shaped rods on the Leksell localization box. The irradiated phantom was MR imaged at 1.5 T employing a T2-weighted pulse sequence. Four image series were acquired by alternating the frequency encoding axis and reversing the read gradient polarity, thus allowing the characterization of the MR-related spatial distortions. Results: MR spatial distortions stemming from main field (B{sub 0}) inhomogeneity as well as from susceptibility and chemical shift phenomena (also known as sequence dependent distortions) were found to be of the order of 0.5 mm, while those owing to gradient nonlinearities (also known as sequence independent distortions) were found to increase with distance from the MR scanner isocenter extending up to 0.47 mm at an Euclidean distance of 69.6 mm. Regarding the LGP image registration procedure, the corresponding average contribution to the total

  1. Effects of bone- and air-tissue inhomogeneities on the dose distributions of the Leksell Gamma Knife® calculated with PENELOPE

    NASA Astrophysics Data System (ADS)

    Al-Dweri, Feras M. O.; Rojas, E. Leticia; Lallena, Antonio M.

    2005-12-01

    Monte Carlo simulation with PENELOPE (version 2003) is applied to calculate Leksell Gamma Knife® dose distributions for heterogeneous phantoms. The usual spherical water phantom is modified with a spherical bone shell simulating the skull and an air-filled cube simulating the frontal or maxillary sinuses. Different simulations of the 201 source configuration of the Gamma Knife have been carried out with a simplified model of the geometry of the source channel of the Gamma Knife recently tested for both single source and multisource configurations. The dose distributions determined for heterogeneous phantoms including the bone- and/or air-tissue interfaces show non-negligible differences with respect to those calculated for a homogeneous one, mainly when the Gamma Knife isocentre approaches the separation surfaces. Our findings confirm an important underdosage (~10%) nearby the air-tissue interface, in accordance with previous results obtained with the PENELOPE code with a procedure different from ours. On the other hand, the presence of the spherical shell simulating the skull produces a few per cent underdosage at the isocentre wherever it is situated.

  2. Calibration of the Gamma Knife Perfexion using TG-21 and the solid water Leksell dosimetry phantom

    SciTech Connect

    McDonald, Daniel; Yount, Caroline; Koch, Nicholas; Ashenafi, Michael; Peng, Jean; Vanek, Kenneth

    2011-03-15

    Purpose: To calibrate a Gamma Knife (GK) Perfexion using TG-21 with updated chamber-dependent values for modern microionization chambers in the new solid water Leksell dosimetry phantom. This work illustrates a calibration method using commercially available equipment, instruments, and an established dosimetry protocol that may be adopted at any GK center, thus reducing the interinstitutional variation in GK calibration. The calibration was verified by three third-party dosimetry checks. In addition, measurements of the relative output factors are presented and compared to available data and the new manufacturer-provided relative output factors yet to be released. Methods: An absolute dose calibration based on the TG-21 formalism, utilizing recently reported phantom material and chamber-dependent factors, was performed using a microionization chamber in a spherical solid water phantom. The result was compared to other calibration protocols based on TG-51. Independent verification of the machine output was conducted through M.D. Anderson Dosimetry Services (MDADS), using thermoluminescent dosimeters (TLDs) in an anthropomorphic head phantom; the Radiological Physics Center (RPC), using TLDs in the standard Elekta ABS plastic calibration phantom (gray phantom), included with the GK; and through a collaborative international calibration survey by the University of Pittsburgh Medical Center (UPMC) using alanine dosimeters, also in the gray phantom. The alanine dosimeters were read by the National Institute of Standards and Technology. Finally, Gafchromic EBT film was used to measure relative output factors and these factors were compared to values reported in the literature as well as new values announced for release by Elekta. The films were exposed in the solid water phantom using an included film insert accessory. Results: Compared to the TG-21 protocol in the solid water phantom, the modified and unmodified TG-51 calibrations resulted in dose rates which were 1

  3. Recurrent tumor vs radiation effects after Gamma Knife radiosurgery of intracerebral metastases: Diagnosis with PET-FDG

    SciTech Connect

    Mogard, J.; Kihlstroem, L.; Ericson, K. |

    1994-03-01

    Our objective was to differentiate radiation effects from tumor progression in metastases stereotaxically irradiated with the multicobalt unit (Gamma Knife). Eleven patients with stereotaxically irradiated cerebral metastases were examined with PET using [{sup 18}F]fluorodeoxyglucose (FDG) to differentiate recurrent tumor from radiation effects. Six patients had increased uptake of FDG, and clinical, radiological, and pathological findings confirmed the diagnosis of recurrent metastases. These patients had an unfavorable prognosis and were all dead within 54 weeks after radiosurgery. Five patients had lesions without an increased accumulation of FDG. Four of these patients were alive after a total follow-up of 1.7 years, while one patient died of a peptic ulcer 56 weeks after radiosurgery. Positron emission tomography with FDG was of obvious prognostic value in this small series of patients and was clearly superior to CT and MR in the distinction between tumor recurrence and radiation effects (verified necrosis in one case). 24 refs., 2 figs., 2 tabs.

  4. Linear Accelerator and Gamma Knife-Based Stereotactic Cranial Radiosurgery: Challenges and Successes of Existing Quality Assurance Guidelines and Paradigms

    SciTech Connect

    Goetsch, Steven J.

    2008-05-01

    Intracranial stereotactic radiosurgery has been practiced since 1951. The technique has expanded from a single dedicated unit in Stockholm in 1968 to hundreds of centers performing an estimated 100,000 Gamma Knife and linear accelerator cases in 2005. The radiation dosimetry of small photon fields used in this technique has been well explored in the past 15 years. Quality assurance recommendations have been promulgated in refereed reports and by several national and international professional societies since 1991. The field has survived several reported treatment errors and incidents, generally reacting by strengthening standards and precautions. An increasing number of computer-controlled and robotic-dedicated treatment units are expanding the field and putting patients at risk of unforeseen errors. Revisions and updates to previously published quality assurance documents, and especially to radiation dosimetry protocols, are now needed to ensure continued successful procedures that minimize the risk of serious errors.

  5. Assessment of variation in Elekta plastic spherical-calibration phantom and its impact on the Leksell Gamma Knife calibration

    SciTech Connect

    Novotny, Josef Jr.; Bhatnagar, Jagdish P.; Chung, Hyun-Tai; Johansson, Jonas; Bednarz, Greg; Ma, Lijun; Saiful Huq, M.

    2010-09-15

    Purpose: Traditionally, the dose-rate calibration (output) of the Leksell Gamma Knife (LGK) unit is performed using a 160 mm diameter plastic spherical phantom provided by the vendor of the LGK, Elekta Instrument AB. The purpose of this study was to evaluate variations in the Elekta spherical phantom and to assess its impact and use for the LGK calibration. Methods: Altogether, 13 phantoms from six different centers were acquired, 10 of these phantoms were manufactured within the past 10 years and the last 3 approximately 15-20 years ago. To assess variation in phantoms, the diameter and mass densities were measured. To assess the impact on LGK calibration, the output of two models of LGK (LGK Perfexion and LGK 4C) were measured under identical irradiation conditions using all 13 phantoms for each LGK model. Results: The mean measured deviation in diameter from expected nominal 160 mm for 13 phantoms was 0.51 mm (range of 0.09-1.51 mm). The mean measured phantom mass density for 13 phantoms was 1.066{+-}0.019 g/cm{sup 3} (range of 1.046-1.102 g/cm{sup 3}). The percentage deviation of output for individual phantom from mean of 13 phantom outputs ranged from -0.37% to 0.55% for LGK Perfexion. Similarly, the percentage deviation of output for individual phantom from mean of 13 phantom outputs ranged from -0.72% to 0.47% for LGK 4C. Conclusions: This study demonstrated that small variations in terms of phantom size and mass density of the phantom material do not have a significant impact on dose-rate measurements of the Leksell Gamma Knife. Also, date of manufacture of the phantom did not show up to be a significant factor in this study.

  6. Quality of life after gamma knife radiosurgery treatment in patients with a vestibular schwannoma: the patient’s perspective

    PubMed Central

    van Haren, Anniek E. P.; Mulder, Jef J. S.; Hanssens, Patrick E. J.; van Overbeeke, Jacobus J.; Cremers, Cor W. R. J.; Graamans, Kees

    2009-01-01

    This study evaluates the impact of gamma knife radiosurgery (GKRS) on the quality of life (QOL) of patients with a sporadic vestibular schwannoma (VS). This study pertains to 108 VS patients who had GKRS in the years 2003 through 2007. Two different QOL questionnaires were used: medical outcome study short form 36 (SF36) and Glasgow benefit inventory (GBI). Radiosurgery was performed using a Leksell 4C gamma knife. The results of the QOL questionnaires in relation to prospectively and retrospectively gathered data of the VS patients treated by GKRS. Eventually, 97 patients could be included in the study. Their mean tumor size was 17 mm (range 6–39 mm); the mean maximum dose on the tumor was 19.9 Gy (range 16–25.5 Gy) and the mean marginal dose on the tumor was 11.1 (range 9.3–12.5 Gy). SF36 scores showed results comparable to those for a normal Dutch population. GBI showed a marginal decline in QOL. No correlation was found between QOL and gender, age, tumor size, or radiation dose. Increased audiovestibular symptoms after GKRS were correlated with a decreased GBI score, and decreased symptoms were correlated with a higher QOL post-GKRS. In this study shows that GKRS for VS has little impact on the general QOL of the VS patient. However, there is a wide range in individual QOL results. Individual QOL was influenced by the audiovestibular symptoms. No predictive patient, tumor, or treatment factors for QOL outcome after GKRS could be determined. Comparison with microsurgery is difficult because of intra group variability. PMID:19894058

  7. MRI-based polymer gel dosimetry for validating plans with multiple matrices in Gamma Knife stereotactic radiosurgery.

    PubMed

    Gopishankar, N; Watanabe, Yoichi; Subbiah, Vivekanandhan

    2011-01-01

    One of treatment planning techniques with Leksell GammaPlan (LGP) for Gamma Knife stereotactic radiosurgery (GKSRS) uses multiple matrices with multiple dose prescriptions. Computational complexity increases when shots are placed in multiple matrices with different grid sizes. Hence, the experimental validation of LGP calculated dose distributions is needed for those cases. For the current study, we used BANG3 polymer gel contained in a head-sized glass bottle to simulate the entire treatment process of GKSRS. A treatment plan with three 18 mm shots and one 8 mm shot in separate matrices was created with LGP. The prescribed maximum dose was 8 Gy to three shots and 16 Gy to one of the 18 mm shots. The 3D dose distribution recorded in the gel dosimeter was read using a Siemens 3T MRI scanner. The scanning parameters of a CPMG pulse sequence with 32 equidistant echoes were as follows: TR = 7 s, echo step = 13.6 ms, field-of-view = 256 mm × 256 mm, and pixel size = 1 mm × 1 mm. Interleaved acquisition mode was used to obtain 15 to 45 2-mm-thick slices. Using a calibration relationship between absorbed dose and the spin-spin relaxation rate (R2), we converted R2 images to dose images. MATLAB-based in-house programs were used for R2 estimation and dose comparison. Gamma-index analysis for the 3D data showed gamma values less than unity for 86% of the voxels. Through this study we accomplished the first application of polymer gel dosimetry for a true comparison between measured 3D dose distributions and LGP calculations for plans using multiple matrices for multiple targets. PMID:21587176

  8. Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation

    NASA Astrophysics Data System (ADS)

    Priegnitz, M.; Helmbrecht, S.; Janssens, G.; Perali, I.; Smeets, J.; Vander Stappen, F.; Sterpin, E.; Fiedler, F.

    2015-06-01

    Proton and ion beam therapies become increasingly relevant in radiation therapy. To fully exploit the potential of this irradiation technique and to achieve maximum target volume conformality, the verification of particle ranges is highly desirable. Many research activities focus on the measurement of the spatial distributions of prompt gamma rays emitted during irradiation. A passively collimating knife-edge slit camera is a promising option to perform such measurements. In former publications, the feasibility of accurate detection of proton range shifts in homogeneous targets could be shown with such a camera. We present slit camera measurements of prompt gamma depth profiles in inhomogeneous targets. From real treatment plans and their underlying CTs, representative beam paths are selected and assembled as one-dimensional inhomogeneous targets built from tissue equivalent materials. These phantoms have been irradiated with monoenergetic proton pencil beams. The accuracy of range deviation estimation as well as the detectability of range shifts is investigated in different scenarios. In most cases, range deviations can be detected within less than 2 mm. In close vicinity to low-density regions, range detection is challenging. In particular, a minimum beam penetration depth of 7 mm beyond a cavity is required for reliable detection of a cavity filling with the present setup. Dedicated data post-processing methods may be capable of overcoming this limitation.

  9. Ten-Year Survival of a Patient Treated with Stereotactic Gamma Knife Radiosurgery for Brain Metastases from Colon Cancer with Ovarian and Lymph Node Metastases: A Case Report.

    PubMed

    Morinaga, Nobuhiro; Tanaka, Naritaka; Shitara, Yoshinori; Ishizaki, Masatoshi; Yoshida, Takatomo; Kouga, Hideaki; Wakabayashi, Kazuki; Fukuchi, Minoru; Tsunoda, Yoshiyuki; Kuwano, Hiroyuki

    2016-01-01

    Brain metastasis from colorectal cancer is infrequent and carries a poor prognosis. Herein, we present a patient alive 10 years after the identification of a first brain metastasis from sigmoid colon cancer. A 39-year-old woman underwent sigmoidectomy for sigmoid colon cancer during an emergency operation for pelvic peritonitis. The pathological finding was moderately differentiated adenocarcinoma. Eleven months after the sigmoidectomy, a metastatic lesion was identified in the left ovary. Despite local radiotherapy followed by chemotherapy, the left ovarian lesion grew, so resection of the uterus and bilateral ovaries was performed. Adjuvant chemotherapy with tegafur-uracil (UFT)/calcium folinate (leucovorin, LV) was initiated. Seven months after resection of the ovarian lesion, brain metastases appeared in the bilateral frontal lobes and were treated with stereotactic Gamma Knife radiosurgery. Cervical and mediastinal lymph node metastases were also diagnosed, and irradiation of these lesions was performed. After radiotherapy, 10 courses of oxaliplatin and infused fluorouracil plus leucovorin (FOLFOX) were administered. During FOLFOX administration, recurrent left frontal lobe brain metastasis was diagnosed and treated with stereotactic Gamma Knife radiosurgery. In this case, the brain metastases were well treated with stereotactic Gamma Knife radiosurgery, and the systemic disease arising from sigmoid colon cancer has been kept under control with chemotherapies, surgical resection, and radiotherapy. PMID:27403125

  10. Ten-Year Survival of a Patient Treated with Stereotactic Gamma Knife Radiosurgery for Brain Metastases from Colon Cancer with Ovarian and Lymph Node Metastases: A Case Report

    PubMed Central

    Morinaga, Nobuhiro; Tanaka, Naritaka; Shitara, Yoshinori; Ishizaki, Masatoshi; Yoshida, Takatomo; Kouga, Hideaki; Wakabayashi, Kazuki; Fukuchi, Minoru; Tsunoda, Yoshiyuki; Kuwano, Hiroyuki

    2016-01-01

    Brain metastasis from colorectal cancer is infrequent and carries a poor prognosis. Herein, we present a patient alive 10 years after the identification of a first brain metastasis from sigmoid colon cancer. A 39-year-old woman underwent sigmoidectomy for sigmoid colon cancer during an emergency operation for pelvic peritonitis. The pathological finding was moderately differentiated adenocarcinoma. Eleven months after the sigmoidectomy, a metastatic lesion was identified in the left ovary. Despite local radiotherapy followed by chemotherapy, the left ovarian lesion grew, so resection of the uterus and bilateral ovaries was performed. Adjuvant chemotherapy with tegafur-uracil (UFT)/calcium folinate (leucovorin, LV) was initiated. Seven months after resection of the ovarian lesion, brain metastases appeared in the bilateral frontal lobes and were treated with stereotactic Gamma Knife radiosurgery. Cervical and mediastinal lymph node metastases were also diagnosed, and irradiation of these lesions was performed. After radiotherapy, 10 courses of oxaliplatin and infused fluorouracil plus leucovorin (FOLFOX) were administered. During FOLFOX administration, recurrent left frontal lobe brain metastasis was diagnosed and treated with stereotactic Gamma Knife radiosurgery. In this case, the brain metastases were well treated with stereotactic Gamma Knife radiosurgery, and the systemic disease arising from sigmoid colon cancer has been kept under control with chemotherapies, surgical resection, and radiotherapy. PMID:27403125

  11. SU-E-T-476: Quality Assurance for Gamma Knife Perfexion Using the Exradin W1 Plastic Scintillation Detector

    SciTech Connect

    Pino, R; Therriault-Proulx, F; Yang, J; Beddar, S

    2014-06-01

    Purpose: To perform dose profile and output factor measurements for the Exradin W1 plastic scintillation detector (PSD) for the Gamma Knife Perfexion (GKP) collimators in a Lucy phantom and to compare these values to an Exradin A16 ion chamber, EBT3 radiochromic film and treatment planning system (TPS) data. Methods: We used the Exradin W1 PSD which has a small volume, near-water equivalent sensitive element. It has also been shown to be energy independent. This new detector is manufactured and distributed by Standard Imaging, Inc. Measurements were performed for all three collimators (4 mm, 8 mm and 16 mm) for the GKP. The Lucy phantom with the PSD inserted was moved in small steps to acquire profiles in all three directions. EBT3 film was inserted in the Lucy phantom and exposed to a single shot for each collimator. Relative output factors were measured using the three detectors while profiles acquired with the PSD were compared to the ones measured with EBT3 radiochromic film. Results: Measured output factors relative to the largest collimator are as followsCollimator PS EBT3 A1616mm 1.000 1.000 1.0008mm 0.892 0.881 0.8834mm 0.795 0.793 0.727 The nominal (vendor) OFs for GKP are 1.000, 0.900, and 0.814, for collimators 16 mm, 8 mm and 4 mm, respectively. There is excellent agreement between all profiles measured with the PSD and EBT3 as well as with the TPS data provided by the vendor. Conclusion: Output factors measured with the W1 were consistent with the ones measured with EBT3 and A16 ion chamber. Measured profiles are in excellent agreement. The W1 detector seems well suited for beam QA for Gamma Knife due to its dosimetric characteristics. Sam Beddar would like to disclose a NIH/NCI SBIR Phase II grant (2R44CA153824-02A1) with Standard Imaging, Title: “Water-Equivalent Plastic Scintillation Detectors for Small Field Radiotherapy”.

  12. Automated gamma knife radiosurgery treatment planning with image registration, data-mining, and Nelder-Mead simplex optimization

    SciTech Connect

    Lee, Kuan J.; Barber, David C.; Walton, Lee

    2006-07-15

    Gamma knife treatments are usually planned manually, requiring much expertise and time. We describe a new, fully automatic method of treatment planning. The treatment volume to be planned is first compared with a database of past treatments to find volumes closely matching in size and shape. The treatment parameters of the closest matches are used as starting points for the new treatment plan. Further optimization is performed with the Nelder-Mead simplex method: the coordinates and weight of the isocenters are allowed to vary until a maximally conformal plan specific to the new treatment volume is found. The method was tested on a randomly selected set of 10 acoustic neuromas and 10 meningiomas. Typically, matching a new volume took under 30 seconds. The time for simplex optimization, on a 3 GHz Xeon processor, ranged from under a minute for small volumes (<1000 cubic mm, 2-3 isocenters), to several tens of hours for large volumes (>30 000 cubic mm,>20 isocenters). In 8/10 acoustic neuromas and 8/10 meningiomas, the automatic method found plans with conformation number equal or better than that of the manual plan. In 4/10 acoustic neuromas and 5/10 meningiomas, both overtreatment and undertreatment ratios were equal or better in automated plans. In conclusion, data-mining of past treatments can be used to derive starting parameters for treatment planning. These parameters can then be computer optimized to give good plans automatically.

  13. Automated gamma knife radiosurgery treatment planning with image registration, data-mining, and Nelder-Mead simplex optimization.

    PubMed

    Lee, Kuan J; Barber, David C; Walton, Lee

    2006-07-01

    Gamma knife treatments are usually planned manually, requiring much expertise and time. We describe a new, fully automatic method of treatment planning. The treatment volume to be planned is first compared with a database of past treatments to find volumes closely matching in size and shape. The treatment parameters of the closest matches are used as starting points for the new treatment plan. Further optimization is performed with the Nelder-Mead simplex method: the coordinates and weight of the isocenters are allowed to vary until a maximally conformal plan specific to the new treatment volume is found. The method was tested on a randomly selected set of 10 acoustic neuromas and 10 meningiomas. Typically, matching a new volume took under 30 seconds. The time for simplex optimization, on a 3 GHz Xeon processor, ranged from under a minute for small volumes (<1000 cubic mm, 2-3 isocenters), to several tens of hours for large volumes (>30,000 cubic mm, >20 isocenters). In 8/10 acoustic neuromas and 8/10 meningiomas, the automatic method found plans with conformation number equal or better than that of the manual plan. In 4/10 acoustic neuromas and 5/10 meningiomas, both overtreatment and undertreatment ratios were equal or better in automated plans. In conclusion, data-mining of past treatments can be used to derive starting parameters for treatment planning. These parameters can then be computer optimized to give good plans automatically. PMID:16898457

  14. Development of a Monte Carlo model for treatment planning dose verification of the Leksell Gamma Knife Perfexion radiosurgery system.

    PubMed

    Yuan, Jiankui; Lo, Simon S; Zheng, Yiran; Sohn, Jason W; Sloan, Andrew E; Ellis, Rodney; Machtay, Mitchell; Wessels, Barry

    2016-01-01

    Detailed Monte Carlo (MC) modeling of the Leksell Gamma Knife (GK) Perfexion (PFX) collimator system is the only accurate ab initio approach appearing in the literature. As a different approach, in this work, we present a MC model based on film measurement. By adjusting the model parameters and fine-tuning the derived fluence map for each individual source to match the manufacturer's ring output factors, we created a reasonable virtual source model for MC simulations to verify treatment planning dose for the GK PFX radiosurgery system. The MC simulation model was commissioned by simple single shots. Dose profiles and both ring and collimator output factors were compared with the treatment planning system (TPS). Good agreement was achieved for dose profiles especially for the region of plateau (< 2%), while larger difference (< 5%) came from the penumbra region. The maximum difference of the calculated output factor was within 0.7%. The model was further validated by a clinical test case. Good agreement was obtained. The DVHs for brainstem and the skull were almost identical and, for the target, the volume covered by the prescription (12.5 Gy to 50% isodose line) was 95.6% from MC calculation versus 100% from the TPS. PMID:27455497

  15. 12 Gy gamma knife radiosurgical volume is a predictor for radiation necrosis in non-AVM intracranial tumors

    SciTech Connect

    Korytko, Timothy; Radivoyevitch, Tomas; Colussi, Valdir; Wessels, Barry W.; Pillai, Kunjan; Maciunas, Robert J.; Einstein, Douglas B. . E-mail: Douglas.Einstein@uhhs.com

    2006-02-01

    Purpose: To determine whether the 12-Gy radiosurgical volume (12-GyV) correlates with the development of postradiosurgical imaging changes suggestive of radiation necrosis in patients treated for non-arteriovenous malformation (non-AVM) intracranial tumors with gamma knife stereotactic radiosurgery (GKSRS). Methods and Materials: A retrospective single-institution review of 129 patients with 198 separate non-AVM tumors was performed. Patients were followed with magnetic resonance imaging (MRI) and physical examinations at 3- to 6-month intervals. Patients who developed postradiosurgical MRI changes suggestive of radiation necrosis were labeled as having either symptomatic radiation necrosis (S-NEC) if they experienced any decline in neurologic examination associated with the imaging changes, or asymptomatic radiation necrosis (A-NEC) if they had a stable or improving neurologic examination. Results: 12-GyV correlated with risk of S-NEC, which was 23% (for 12-GyV of 0-5 cc), 20% (5-10 cc), 54% (10-15 cc), and 57% (>15 cc). The risk of A-NEC did not significantly change with 12-GyV. Logistic regression analyses showed that the following factors were associated with the development of S-NEC: 12-GyV (p < 0.01), occipital and temporal lesions (p < 0.01), previous whole-brain radiotherapy (p = 0.03), and male sex (p 0.03). Radiosurgical plan conformality did not correlate with the development of S-NEC. Conclusion: The risk of S-NEC, but not A-NEC after GKSRS for non-AVM tumors correlates with 12-GyV, and increases significantly for 12-GyV >10 cc.

  16. Experimental Comparison of Knife-Edge and Multi-Parallel Slit Collimators for Prompt Gamma Imaging of Proton Pencil Beams

    PubMed Central

    Smeets, Julien; Roellinghoff, Frauke; Janssens, Guillaume; Perali, Irene; Celani, Andrea; Fiorini, Carlo; Freud, Nicolas; Testa, Etienne; Prieels, Damien

    2016-01-01

    More and more camera concepts are being investigated to try and seize the opportunity of instantaneous range verification of proton therapy treatments offered by prompt gammas emitted along the proton tracks. Focusing on one-dimensional imaging with a passive collimator, the present study experimentally compared in combination with the first, clinically compatible, dedicated camera device the performances of instances of the two main options: a knife-edge slit (KES) and a multi-parallel slit (MPS) design. These two options were experimentally assessed in this specific context as they were previously demonstrated through analytical and numerical studies to allow similar performances in terms of Bragg peak retrieval precision and spatial resolution in a general context. Both collimators were prototyped according to the conclusions of Monte Carlo optimization studies under constraints of equal weight (40 mm tungsten alloy equivalent thickness) and of the specificities of the camera device under consideration (in particular 4 mm segmentation along beam axis and no time-of-flight discrimination, both of which less favorable to the MPS performance than to the KES one). Acquisitions of proton pencil beams of 100, 160, and 230 MeV in a PMMA target revealed that, in order to reach a given level of statistical precision on Bragg peak depth retrieval, the KES collimator requires only half the dose the present MPS collimator needs, making the KES collimator a preferred option for a compact camera device aimed at imaging only the Bragg peak position. On the other hand, the present MPS collimator proves more effective at retrieving the entrance of the beam in the target in the context of an extended camera device aimed at imaging the whole proton track within the patient. PMID:27446802

  17. Experimental Comparison of Knife-Edge and Multi-Parallel Slit Collimators for Prompt Gamma Imaging of Proton Pencil Beams.

    PubMed

    Smeets, Julien; Roellinghoff, Frauke; Janssens, Guillaume; Perali, Irene; Celani, Andrea; Fiorini, Carlo; Freud, Nicolas; Testa, Etienne; Prieels, Damien

    2016-01-01

    More and more camera concepts are being investigated to try and seize the opportunity of instantaneous range verification of proton therapy treatments offered by prompt gammas emitted along the proton tracks. Focusing on one-dimensional imaging with a passive collimator, the present study experimentally compared in combination with the first, clinically compatible, dedicated camera device the performances of instances of the two main options: a knife-edge slit (KES) and a multi-parallel slit (MPS) design. These two options were experimentally assessed in this specific context as they were previously demonstrated through analytical and numerical studies to allow similar performances in terms of Bragg peak retrieval precision and spatial resolution in a general context. Both collimators were prototyped according to the conclusions of Monte Carlo optimization studies under constraints of equal weight (40 mm tungsten alloy equivalent thickness) and of the specificities of the camera device under consideration (in particular 4 mm segmentation along beam axis and no time-of-flight discrimination, both of which less favorable to the MPS performance than to the KES one). Acquisitions of proton pencil beams of 100, 160, and 230 MeV in a PMMA target revealed that, in order to reach a given level of statistical precision on Bragg peak depth retrieval, the KES collimator requires only half the dose the present MPS collimator needs, making the KES collimator a preferred option for a compact camera device aimed at imaging only the Bragg peak position. On the other hand, the present MPS collimator proves more effective at retrieving the entrance of the beam in the target in the context of an extended camera device aimed at imaging the whole proton track within the patient. PMID:27446802

  18. Measurement of relative output factors for the 8 and 4 mm collimators of Leksell Gamma Knife Perfexion by film dosimetry

    SciTech Connect

    Novotny, Josef Jr.; Bhatnagar, Jagdish P.; Quader, Mubina A.; Bednarz, Greg; Lunsford, L. Dade; Huq, M. Saiful

    2009-05-15

    Three types of films, Kodak EDR2, Gafchromic EBT, and Gafchromic MD-V2-55, were used to measure relative output factors of 4 and 8 mm collimators of the Leksell Gamma Knife Perfexion. The optical density to dose calibration curve for each of the film types was obtained by exposing the films to a range of known doses. Ten data points were acquired for each of the calibration curves in the dose ranges from 0 to 4 Gy, 0 to 8 Gy, and 0 to 80 Gy for Kodak EDR2, Gafchromic EBT, and Gafchromic MD-V2-55 films, respectively. For the measurement of relative output factors, five films of each film type were exposed to a known dose. All films were scanned using EPSON EXPRESSION 10000 XL scanner with 200 dpi resolution in 16 bit gray scale for EDR2 film and 48 bit color scale for Gafchromic films. The scanned images were imported in the red channel for both Gafchromic films. The background corrections from an unexposed film were applied to all films. The output factors obtained from film measurements were in a close agreement both with the Monte Carlo calculated values of 0.924 and 0.805 for 8 and 4 mm collimators, respectively. These values are provided by the vendor and used as default values in the vendor's treatment planning system. The largest differences were noted for the Kodak EDR 2 films (-2.1% and -4.5% for 8 and 4 mm collimators, respectively). The best agreement observed was for EBT Gafchromic film (-0.8% and +0.6% differences for 8 and 4 mm collimators, respectively). Based on the present values, no changes in the default relative output factor values were made in the treatment planning system.

  19. Toxicity of Gamma Knife Radiosurgery in the Treatment of Intracranial Tumors in Patients With Collagen Vascular Diseases or Multiple Sclerosis

    SciTech Connect

    Lowell, Dot; Tatter, Stephen B.; Bourland, J. Daniel; Guzman, Allan F. de; Ekstrand, Kenneth E.; Ellis, Thomas L.; Lovato, James F.; McMullen, Kevin P.; Munley, Michael T.; Shaw, Edward G.; Urbanic, James J.; Chan, Michael D.

    2011-11-15

    Purpose: To assess toxicity in patients with either a collagen vascular disease (CVD) or multiple sclerosis (MS) treated with intracranial radiosurgery. Methods and Materials: Between January 2004 and April 2009, 6 patients with MS and 14 patients with a CVD were treated with Gamma Knife radiosurgery (GKRS) for intracranial tumors. Treated lesions included 15 total brain metastases in 7 patients, 11 benign brain tumors, 1 low grade glioma, and 1 cavernous malformation. Toxicities were graded by the Radiation Therapy Oncology Group Acute/Late Radiation Morbidity Scoring Criteria. 'Rare toxicities' were characterized as those reported in the scientific literature at an incidence of <5%. Results: Median follow-up time was 16 months. Median dose to the tumor margin was 13.0 Gy (range, 12-21 Gy). Median size of tumor was 5.0 cm{sup 3} (range, 0.14-7.8 cm{sup 3}). Of the 14 patients with CVD, none experienced a Grade 3 or 4 toxicity or a toxicity characterized as rare. Of the 6 patients with MS, 3 experienced rare toxicities, and two of these were Grade 3 toxicities. Rare complications included a patient experiencing both communicating hydrocephalus and facial nerve palsy, as well as 2 additional patients with motor cranial nerve palsy. High-grade toxicities included the patient with an acoustic neuroma requiring ventriculoperitoneal shunt placement for obstructive hydrocephalus, and 1 patient with a facial nerve schwannoma who experienced permanent facial nerve palsy. Interval between radiosurgery and high-grade toxicities ranged from 1 week to 4 months. Conclusions: Our series suggests that patients with MS who receive GKRS may be at increased risk of rare and high-grade treatment-related toxicity. Given the time course of toxicity, treatment-related edema or demyelination represent potential mechanisms.

  20. Dosimetric and Clinical Analysis of Spatial Distribution of the Radiation Dose in Gamma Knife Radiosurgery for Vestibular Schwannoma

    SciTech Connect

    Massager, Nicolas; Lonneville, Sarah; Delbrouck, Carine; Benmebarek, Nadir; Desmedt, Francoise; Devriendt, Daniel

    2011-11-15

    Objectives: We investigated variations in the distribution of radiation dose inside (dose inhomogeneity) and outside (dose falloff) the target volume during Gamma Knife (GK) irradiation of vestibular schwannoma (VS). We analyzed the relationship between some parameters of dose distribution and the clinical and radiological outcome of patients. Methods and Materials: Data from dose plans of 203 patients treated for a vestibular schwannoma by GK C using same prescription dose (12 Gy at the 50% isodose) were collected. Four different dosimetric indexes were defined and calculated retrospectively in all plannings on the basis of dose-volume histograms: Paddick conformity index (PI), gradient index (GI), homogeneity index (HI), and unit isocenter (UI). The different measures related to distribution of the radiation dose were compared with hearing and tumor outcome of 203 patients with clinical and radiological follow-up of minimum 2 years. Results: Mean, median, SD, and ranges of the four indexes of dose distribution analyzed were calculated; large variations were found between dose plans. We found a high correlation between the target volume and PI, GI, and UI. No significant association was found between the indexes of dose distribution calculated in this study and tumor control, tumor volume shrinkage, hearing worsening, loss of functional hearing, or complete hearing loss at last follow-up. Conclusions: Parameters of distribution of the radiation dose during GK radiosurgery for VS can be highly variable between dose plans. The tumor and hearing outcome of patients treated is not significantly related to these global indexes of dose distribution inside and around target volume. In GK radiosurgery for VS, the outcome seems more to be influenced by local radiation dose delivered to specific structures or volumes than by global dose gradients.

  1. Validity of the Graded Prognostic Assessment-Derived Index to Predict Brain-Metastatic Patients' Survival After Gamma Knife Radiosurgery

    SciTech Connect

    Chiou, Shang-Ming

    2010-11-15

    Purpose: To appraise whether the graded prognostic assessment (GPA)-derived index is valid for selecting patients with brain metastases for Gamma Knife (GK) radiosurgery. Methods and Materials: A total of 56 consecutive patients in recursive partioning analysis (RPA) Class I (n = 19, 34%) and II (n = 37, 66%) formed the basis of this retrospective study. Their mean age was of 57 years with mean Karnofsky performance score of 77. Primary cancers stemmed mainly from the lungs (59%). A total of 45 patients (80%) harbored multiple tumors. The mean clinical follow-up period was 9 months. Results: Kaplan-Meier analysis demonstrated that the overall median survival time (MST) for the whole series was 11.5 months: 16.5 vs. 6.5 months for RPA class I and II (p = 0.017). Multivariate Cox analysis revealed that female patients and a pre-GK good functional state were favorable prognostic factors. The favorable MST was in patients with a GPA score of 3 to 4 (17 months) followed by a GPA score of 2 to 2.5 (11 months) and GPA score 0 to 1.5 (6.5 months), but without statistical differences (p = 0.413) in between. A modified index (MGPA) is proposed with gender as a cofactor, then there existed a distinct survival differences (p = 0.028) between patients with an MGPA score of 3.5 to 5 (15 months) and with an MGPA score of 0 to 3 (7 months). In addition, the original GPA index failed to imply the difference of MST in patients with lung origin. Conclusions: The GPA-derived index is not applicable to our set of patients for comparing their survival after GK radiosurgery. The gender of the patients is a suggested cofactor to further refine the greater prognostic accuracy of the GPA index.

  2. Gamma Knife radiosurgery combined with stereotactic aspiration as an effective treatment method for large cystic brain metastases

    PubMed Central

    WANG, HONGWEI; QI, SONGTAO; DOU, CHANGWU; JU, HAITAO; HE, ZHANBIAO; MA, QINGHAI

    2016-01-01

    In the present study, the efficacy and clinical outcomes of stereotactic aspiration combined with the Gamma Knife radiosurgery (GKRS) method were evaluated retrospectively for patients with large cystic brain metastases. This combined method aims to decrease the tumor weight (volume) and increase the possible radiation dose. The present study involved 48 patients who were diagnosed with cystic metastatic brain tumors between January 2008 and December 2012 in the Department of Neurosurgery of Nanfang Hospital Southern Medical University (Guangzhou, China). Every patient underwent Leksell stereotactic frame, 1.5T magnetic resonance imaging (MRI)-guided stereotactic cyst aspiration and Leksell GKRS. Subsequent to the therapy, MRI was performed every 3 months. The results indicated that 48 cases were followed up for 24–72 months, with a mean follow-up duration of 36.2 months. Following treatment, 44 patients (91.7%) exhibited tumor control and 4 patients (8.3%) experienced progression of the local tumor. During this period, 35 patients (72.9%) succumbed, but only 2 (4.2%) of these succumbed to the brain metastases. The total local control rate was 91.7% and the median overall survival time of all patients was 19.5 months. The 1-year overall survival rate was 70.8% and the 2-year overall survival rate was 26.2%. In conclusion, these results indicated that the method of stereotactic cyst aspiration combined with GKRS was safe and effective for patients with large cystic brain metastases. This method is effective for patients whose condition is too weak for general anesthesia and in whom the tumors are positioned at eloquent areas. This method enables patients to avoid a craniotomy, and provides a good tumor control rate, survival time and quality of life. PMID:27347148

  3. Efficacy and Quality of Life Outcomes in Patients With Atypical Trigeminal Neuralgia Treated With Gamma-Knife Radiosurgery

    SciTech Connect

    Dhople, Anil Kwok, Young; Chin, Lawrence; Shepard, David Ph.D.; Slawson, Robert; Amin, Pradip; Regine, William

    2007-10-01

    Purpose: To assess efficacy and quality of life (QOL) outcomes associated with gamma-knife radiosurgery (GK-RS) in treating atypical trigeminal neuralgia (ATN) compared with classic trigeminal neuralgia (CTN). Methods and Materials: Between September 1996 and September 2004, 35 cases of ATN were treated with GK-RS. Patients were categorized into two groups: Group I comprised patients presenting with ATN (57%); Group II consisted of patients presenting with CTN then progressing to ATN (43%). Median prescription dose 75 Gy (range, 70-80 Gy) was delivered to trigeminal nerve root entry zone. Treatment efficacy and QOL improvements were assessed with a standardized questionnaire. Results: With median follow-up of 29 months (range, 3-74 months), 72% reported excellent/good outcomes, with mean time to relief of 5.8 weeks (range, 0-24 weeks) and mean duration of relief of 62 weeks (range, 1-163 weeks). This rate of pain relief is similar to rate achieved in our previously reported experience treating CTN with GK-RS (p = 0.36). There was a trend toward longer time to relief (p = 0.059), and shorter duration of relief (p = 0.067) in patients with ATN. There was no difference in rate of, time to, or duration of pain relief between Groups I and II. Of the patients with ATN, 88% discontinued or decreased the use of pain medications. Among the patients with sustained pain relief, QOL improved an average of 85%. Conclusion: This is the largest reported GK-RS experience for the treatment of ATN. Patients with ATN can achieve rates of pain relief similar to those in patients with CTN. Further follow-up is necessary to assess adequately the durability of response.

  4. Absolute calibration of the Gamma Knife{sup ®} Perfexion™ and delivered dose verification using EPR/alanine dosimetry

    SciTech Connect

    Hornbeck, Amaury E-mail: tristan.garcia@cea.fr; Garcia, Tristan E-mail: tristan.garcia@cea.fr; Cuttat, Marguerite; Jenny, Catherine

    2014-06-15

    Purpose: Elekta Leksell Gamma Knife{sup ®} (LGK) is a radiotherapy beam machine whose features are not compliant with the international calibration protocols for radiotherapy. In this scope, the Laboratoire National Henri Becquerel and the Pitié-Salpêtrière Hospital decided to conceive a new LKG dose calibration method and to compare it with the currently used one. Furthermore, the accuracy of the dose delivered by the LGK machine was checked using an “end-to-end” test. This study also aims to compare doses delivered by the two latest software versions of the Gammaplan treatment planning system (TPS). Methods: The dosimetric method chosen is the electron paramagnetic resonance (EPR) of alanine. Dose rate (calibration) verification was done without TPS using a spherical phantom. Absolute calibration was done with factors calculated by Monte Carlo simulation (MCNP-X). For “end-to-end” test, irradiations in an anthropomorphic head phantom, close to real treatment conditions, are done using the TPS in order to verify the delivered dose. Results: The comparison of the currently used calibration method with the new one revealed a deviation of +0.8% between the dose rates measured by ion chamber and EPR/alanine. For simple fields configuration (less than 16 mm diameter), the “end-to-end” tests showed out average deviations of −1.7% and −0.9% between the measured dose and the calculated dose by Gammaplan v9 and v10, respectively. Conclusions: This paper shows there is a good agreement between the new calibration method and the currently used one. There is also a good agreement between the calculated and delivered doses especially for Gammaplan v10.

  5. Gamma Knife Irradiation of Injured Sciatic Nerve Induces Histological and Behavioral Improvement in the Rat Neuropathic Pain Model

    PubMed Central

    Yagasaki, Yuki; Hayashi, Motohiro; Tamura, Noriko; Kawakami, Yoriko

    2013-01-01

    We examined the effects of gamma knife (GK) irradiation on injured nerves using a rat partial sciatic nerve ligation (PSL) model. GK irradiation was performed at one week after ligation and nerve preparations were made three weeks after ligation. GK irradiation is known to induce immune responses such as glial cell activation in the central nervous system. Thus, we determined the effects of GK irradiation on macrophages using immunoblot and histochemical analyses. Expression of Iba-1 protein, a macrophage marker, was further increased in GK-treated injured nerves as compared with non-irradiated injured nerves. Immunohistochemical study of Iba-1 in GK-irradiated injured sciatic nerves demonstrated Iba-1 positive macrophage accumulation to be enhanced in areas distal to the ligation point. In the same area, myelin debris was also more efficiently removed by GK-irradiation. Myelin debris clearance by macrophages is thought to contribute to a permissive environment for axon growth. In the immunoblot study, GK irradiation significantly increased expressions of βIII-tubulin protein and myelin protein zero, which are markers of axon regeneration and re-myelination, respectively. Toluidine blue staining revealed the re-myelinated fiber diameter to be larger at proximal sites and that the re-myelinated fiber number was increased at distal sites in GK-irradiated injured nerves as compared with non-irradiated injured nerves. These results suggest that GK irradiation of injured nerves facilitates regeneration and re-myelination. In a behavior study, early alleviation of allodynia was observed with GK irradiation in PSL rats. When GK-induced alleviation of allodynia was initially detected, the expression of glial cell line-derived neurotrophic factor (GDNF), a potent analgesic factor, was significantly increased by GK irradiation. These results suggested that GK irradiation alleviates allodynia via increased GDNF. This study provides novel evidence that GK irradiation of

  6. MAGAT gel and EBT2 film-based dosimetry for evaluating source plugging-based treatment plan in Gamma Knife stereotactic radiosurgery.

    PubMed

    Natanasabapathi, Gopishankar; Subbiah, Vivekanandhan; Kale, Shashank Sharad; Rath, Goura Kishor; Senthilkumaran, S; Thulkar, Sanjay; Subramani, Vellaiyan; Laviraj, M A; Bisht, Raj Kishor; Mahapatra, A K

    2012-01-01

    This work illustrates a procedure to assess the overall accuracy associated with Gamma Knife treatment planning using plugging. The main role of source plugging or blocking is to create dose falloff in the junction between a target and a critical structure. We report the use of MAGAT gel dosimeter for verification of an experimental treatment plan based on plugging. The polymer gel contained in a head-sized glass container simulated all major aspects of the treatment process of Gamma Knife radiosurgery. The 3D dose distribution recorded in the gel dosimeter was read using a 1.5T MRI scanner. Scanning protocol was: CPMG pulse sequence with 8 equidistant echoes, TR = 7 s, echo step = 14 ms, pixel size = 0.5mm × 0.5mm, and slice thickness of 2 mm. Using a calibration relationship between absorbed dose and spin-spin relaxation rate (R2), we converted R2 images to dose images. Volumetric dose comparison between treatment planning system (TPS) and gel measurement was accomplished using an in-house MATLAB-based program. The isodose overlay of the measured and computed dose distribution on axial planes was in close agreement. Gamma index analysis of 3D data showed more than 94% voxel pass rate for different tolerance criteria of 3%/2 mm, 3%/1 mm and 2%/2 mm. Film dosimetry with GAFCHROMIC EBT 2 film was also performed to compare the results with the calculated TPS dose. Gamma index analysis of film measurement for the same tolerance criteria used for gel measurement evaluation showed more than 95% voxel pass rate. Verification of gamma plan calculated dose on account of shield is not part of acceptance testing of Leksell Gamma Knife (LGK). Through this study we accomplished a volumetric comparison of dose distributions measured with a polymer gel dosimeter and Leksell GammaPlan (LGP) calculations for plans using plugging. We propose gel dosimeter as a quality assurance (QA) tool for verification of plug-based planning. PMID:23149780

  7. WE-G-BRD-08: End-To-End Targeting Accuracy of the Gamma Knife for Trigeminal Neuralgia

    SciTech Connect

    Brezovich, I; Wu, X; Duan, J; Benhabib, S; Huang, M; Shen, S; Cardan, R; Popple, R

    2014-06-15

    Purpose: Current QA procedures verify accuracy of individual equipment parameters, but may not include CT and MRI localizers. This study uses an end-to-end approach to measure the overall targeting errors in individual patients previously treated for trigeminal neuralgia. Methods: The trigeminal nerve is simulated by a 3 mm long, 3.175 mm (1/8 inch) diameter MRI contrast-filled cavity embedded within a PMMA plastic capsule. The capsule is positioned within the head frame such that the cavity position matches the Gamma Knife coordinates of 10 previously treated patients. Gafchromic EBT2 film is placed at the center of the cavity in coronal and sagittal orientations. The films are marked with a pin prick to identify the cavity center. Treatments are planned for delivery with 4 mm collimators using MRI and CT scans acquired with the clinical localizer boxes and acquisition protocols. Coordinates of shots are chosen so that the cavity is centered within the 50% isodose volume. Following irradiation, the films are scanned and analyzed. Targeting errors are defined as the distance between the pin prick and the centroid of the 50% isodose line. Results: Averaged over 10 patient simulations, targeting errors along the x, y and z coordinates (patient left-to-right, posterior-anterior, head-to-foot) were, respectively, −0.060 +/− 0.363, −0.350 +/− 0.253, and 0.364 +/− 0.191 mm when MRI was used for treatment planning. Planning according to CT exhibited generally smaller errors, namely 0.109 +/− 0.167, −0.191 +/− 0.144, and 0.211 +/− 0.94 mm. The largest errors in MRI and CT planned treatments were, respectively, y = −0.761 and x = 0.428 mm. Conclusion: Unless patient motion or stronger MRI image distortion in actual treatments caused additional errors, all patients received the prescribed dose, i.e., the targeted section of the trig±eminal nerve was contained within the 50% isodose surface in all cases.

  8. Automated medial axis seeding and guided evolutionary simulated annealing for optimization of gamma knife radiosurgery treatment plans

    NASA Astrophysics Data System (ADS)

    Zhang, Pengpeng

    The Leksell Gamma KnifeRTM (LGK) is a tool for providing accurate stereotactic radiosurgical treatment of brain lesions, especially tumors. Currently, the treatment planning team "forward" plans radiation treatment parameters while viewing a series of 2D MR scans. This primarily manual process is cumbersome and time consuming because the difficulty in visualizing the large search space for the radiation parameters (i.e., shot overlap, number, location, size, and weight). I hypothesize that a computer-aided "inverse" planning procedure that utilizes tumor geometry and treatment goals could significantly improve the planning process and therapeutic outcome of LGK radiosurgery. My basic observation is that the treatment team is best at identification of the location of the lesion and prescribing a lethal, yet safe, radiation dose. The treatment planning computer is best at determining both the 3D tumor geometry and optimal LGK shot parameters necessary to deliver a desirable dose pattern to the tumor while sparing adjacent normal tissue. My treatment planning procedure asks the neurosurgeon to identify the tumor and critical structures in MR images and the oncologist to prescribe a tumoricidal radiation dose. Computer-assistance begins with geometric modeling of the 3D tumor's medial axis properties. This begins with a new algorithm, a Gradient-Phase Plot (G-P Plot) decomposition of the tumor object's medial axis. I have found that medial axis seeding, while insufficient in most cases to produce an acceptable treatment plan, greatly reduces the solution space for Guided Evolutionary Simulated Annealing (GESA) treatment plan optimization by specifying an initial estimate for shot number, size, and location, but not weight. They are used to generate multiple initial plans which become initial seed plans for GESA. The shot location and weight parameters evolve and compete in the GESA procedure. The GESA objective function optimizes tumor irradiation (i.e., as close to

  9. Monte Carlo calculated and experimentally determined output correction factors for small field detectors in Leksell Gamma Knife Perfexion beams.

    PubMed

    Benmakhlouf, H; Johansson, J; Paddick, I; Andreo, P

    2015-05-21

    The measurement of output factors (OF) for the small photon beams generated by Leksell Gamma Knife® (LGK) radiotherapy units is a challenge for the physicist due to the under or over estimation of these factors by a vast majority of the detectors commercially available. Output correction factors, introduced in the international formalism published by Alfonso (2008 Med. Phys. 35 5179-86), standardize the determination of OFs for small photon beams by correcting detector-reading ratios to yield OFs in terms of absorbed-dose ratios. In this work output correction factors for a number of detectors have been determined for LGK Perfexion™ (60)Co γ-ray beams by Monte Carlo (MC) calculations and measurements. The calculations were made with the MC system PENELOPE, scoring the energy deposited in the active volume of the detectors and in a small volume of water; the detectors simulated were two silicon diodes, one liquid ionization chamber (LIC), alanine and TLD. The calculated LIC output correction factors were within ± 0.4%, and this was selected as the reference detector for experimental determinations where output correction factors for twelve detectors were measured, normalizing their readings to those of the LIC. The MC-calculated and measured output correction factors for silicon diodes yielded corrections of up to 5% for the smallest LGK collimator size of 4 mm diameter. The air ionization chamber measurements led to extremely large output correction factors, caused by the well-known effect of partial volume averaging. The corrections were up to 7% for the natural diamond detector in the 4 mm collimator, also due to partial volume averaging, and decreased to within about ± 0.6% for the smaller synthetic diamond detector. The LIC, showing the smallest corrections, was used to investigate machine-to-machine output factor differences by performing measurements in four LGK units with different dose rates. These resulted in OFs within ± 0.6% and

  10. The Importance of the Conformality, Heterogeneity, and Gradient Indices in Evaluating Gamma Knife Radiosurgery Treatment Plans for Intracranial Meningiomas

    SciTech Connect

    Balagamwala, Ehsan H.; Suh, John H.; Barnett, Gene H.; Khan, Mohammad K.; Neyman, Gennady; Cai, Rong S.; Vogelbaum, Michael A.; Novak, Eric; Chao, Samuel T.

    2012-08-01

    Purpose: To investigate the relationship between the conformality index (CIn), heterogeneity index (HIn), and gradient index (GIn) and the development of toxicity in patients treated with Gamma Knife radiosurgery (GKRS) for intracranial meningiomas. Methods and Materials: Treatment records of patients treated from 1997 to 2009 with at least 6 months of follow-up were reviewed. The following parameters were collected: CIn, HIn, GIn (ratio of the volume receiving half the prescription isodose to the volume receiving the full prescription isodose), brainstem (BS) maximum dose (MD), BS volume receiving {>=}12 Gy (V12), optic apparatus (OA) MD, OA V8 Gy, OA V10, number of isocenters, number of isocenters outside target volume, and the occurrence of six toxicities. Univariate and multivariate logistic regression modeling were used for analysis. Results: This study included 145 patients (148 meningiomas) with a median follow-up time of 27 months (range, 6-113.9 months). The majority of meningiomas were located in the skull base (53%). The median prescription dose was 13 Gy (range, 10-24 Gy) to the 51.50% (range, 50-92%) isodose. A lower HIn was correlated with a higher GIn (p = 0.007). CIn was not associated with any toxicity. Higher HIn was associated with the development of dizziness (odds ratio [OR] 1.9; p = 0.02), whereas a lower GIn was associated with motor deficits (OR 0.38; p = 0.04) and auditory changes (OR 0.59; p = 0.04). The OA MD, V8, and V12 were not associated with visual changes, but visual changes were associated with a higher number of isocenters outside the target volume (OR 1.93; p = 0.07). BS V12 was correlated with the development of auditory changes (OR 1.05; p = 0.05), whereas patients with higher BS MD tended to have increased toxicity. Conclusions: Close attention must be paid to all three indices (CIn, HIn, GIn) when optimal treatment plans are determined. We recommend that the target CIn should be {<=}2.0, the HIn {<=}2.0, and the GIn {>=}3

  11. SU-D-BRB-04: Plan Quality Comparison of Intracranial Stereotactic Radiosurgery (SRS) for Gamma Knife and VMAT Treatments

    SciTech Connect

    Keeling, V; Algan, O; Ahmad, S; Hossain, S

    2015-06-15

    Purpose: To compare treatment plan quality of intracranial stereotactic radiosurgery (SRS) for VMAT (RapidArc) and Gamma Knife (GK) systems. Methods: Ten patients with 24 tumors (seven with 1–2 and three with 4–6 lesions), previously treated with GK 4C (prescription doses ranging from 14–23 Gy) were re-planned for RapidArc. Identical contour sets were kept on MRI images for both plans with tissues assigned a CT number of zero. RapidArc plans were performed using 6 MV flattening-filter-free (FFF) beams with dose rate of 1400 MU/minute using two to eight arcs with the following combinations: 2 full coplanar arcs and the rest non-coplanar half arcs. Beam selection was based on target depth. Areas that penetrated more than 10 cm of tissue were avoided by creating smaller arcs or using avoidance sectors in optimization. Plans were optimized with jaw tracking and a high weighting to the normal-brain-tissue and Normal-Tissue-Objective without compromising PTV coverage. Plans were calculated on a 1 mm grid size using AAA algorithm and then normalized so that 99% of each target volume received the prescription dose. Plan quality was assessed by target coverage using Paddick Conformity Index (PCI), sparing of normal-brain-tissue through analysis of V4, V8, and V12 Gy, and integral dose. Results: In all cases critical structure dose criteria were met. RapidArc had a higher PCI than GK plans for 23 out of 24 lesions. The average PCI was 0.76±0.21 for RapidArc and 0.46±0.20 for GK plans (p≤0.001), respectively. Integral dose and normal-brain-tissue doses for all criteria were lower for RapidArc in nearly all patients. The average ratio of GK to RapidArc plans was 1.28±0.27 (p=0.018), 1.31±0.25 (p=0.017), 1.81±0.43 (p=0.005), and 1.50±0.61 (p=0.006) for V4, V8, and V12 Gy, and integral dose, respectively. Conclusion: VMAT was capable of producing higher quality treatment plans than GK when using optimal beam geometries and proper optimization techniques.

  12. Monte Carlo calculated and experimentally determined output correction factors for small field detectors in Leksell Gamma Knife Perfexion beams

    NASA Astrophysics Data System (ADS)

    Benmakhlouf, H.; Johansson, J.; Paddick, I.; Andreo, P.

    2015-05-01

    The measurement of output factors (OF) for the small photon beams generated by Leksell Gamma Knife® (LGK) radiotherapy units is a challenge for the physicist due to the under or over estimation of these factors by a vast majority of the detectors commercially available. Output correction factors, introduced in the international formalism published by Alfonso (2008 Med. Phys. 35 5179-86), standardize the determination of OFs for small photon beams by correcting detector-reading ratios to yield OFs in terms of absorbed-dose ratios. In this work output correction factors for a number of detectors have been determined for LGK Perfexion™ 60Co γ-ray beams by Monte Carlo (MC) calculations and measurements. The calculations were made with the MC system PENELOPE, scoring the energy deposited in the active volume of the detectors and in a small volume of water; the detectors simulated were two silicon diodes, one liquid ionization chamber (LIC), alanine and TLD. The calculated LIC output correction factors were within ± 0.4%, and this was selected as the reference detector for experimental determinations where output correction factors for twelve detectors were measured, normalizing their readings to those of the LIC. The MC-calculated and measured output correction factors for silicon diodes yielded corrections of up to 5% for the smallest LGK collimator size of 4 mm diameter. The air ionization chamber measurements led to extremely large output correction factors, caused by the well-known effect of partial volume averaging. The corrections were up to 7% for the natural diamond detector in the 4 mm collimator, also due to partial volume averaging, and decreased to within about ± 0.6% for the smaller synthetic diamond detector. The LIC, showing the smallest corrections, was used to investigate machine-to-machine output factor differences by performing measurements in four LGK units with different dose rates. These resulted in OFs within ± 0.6% and ± 0

  13. Primary Central Nervous System Lymphoma (PCNSL): Analysis of Treatment by Gamma Knife Radiosurgery and Chemotherapy in a Prospective, Observational Study

    PubMed Central

    Alvarez-Pinzon, Andres M; Wolf, Aizik L; Coy, Sammie R; Valerio, Jose E

    2016-01-01

    Background: Primary central nervous system lymphoma (PCNSL) is a rare cancer accounting for less than 3% of primary brain and central nervous system (CNS) tumors. Tissues involved include the brain parenchyma, leptomeninges, eyes, and spinal cord. High-dose methotrexate (MTX) is the gold standard for newly diagnosed PCNSL. However, Gamma Knife radiosurgery (GKRS) may be efficacious as a co-adjuvant treatment. The purpose of this prospective observational cohort study is to determine the effectiveness of MTX in combination with GKRS in the treatment of PCNSL. Methods: This is a prospective, observational cohort study evaluating the treatment of histologically confirmed PCNSL with MTX as a single agent in a dose of 8 g/m2 (control) and treatment with MTX, plus GKRS. Strict inclusion and exclusion criteria were employed. Primary outcomes were measured by survival rate. Secondary outcomes were assessed by the tumor’s responsiveness to treatment and reduction in size as noted on imaging. Results: Between January 2007 and January 2012, 128 charts were evaluated. Included in this evaluation were 73 chemotherapy (control) and 55 chemotherapy, plus GKRS, patients (variable). The follow-up period was 24 to 49 months (mean: 36.9 months). There were no statistically significant differences in patient demographics or histology diagnosis. Patients were treated with GK doses ranging from 11 Gy to 16 Gy (median: 11 Gy). The median survival rate from initial diagnosis was 26.8 months in the chemotherapy group and 47.6 in the chemotherapy, plus GKRS, group (p-value: 0.0034). All lesions showed a complete response after GKRS when evaluated using magnetic resonance imaging after three to eight weeks (mean range: 6.3 weeks). Conclusions: The use of GKRS is non-invasive, safe, and shows rapid success, improving the prognosis of the patient. This noninvasive treatment modality should be considered as an option for patients with PCNSL. In our study, GKRS as a co-adjuvant therapy to

  14. SU-E-T-607: An Experimental Validation of Gamma Knife Based Convolution Algorithm On Solid Acrylic Anthropomorphic Phantom

    SciTech Connect

    Gopishankar, N; Bisht, R K

    2014-06-01

    Purpose: To perform dosimetric evaluation of convolution algorithm in Gamma Knife (Perfexion Model) using solid acrylic anthropomorphic phantom. Methods: An in-house developed acrylic phantom with ion chamber insert was used for this purpose. The middle insert was designed to fit ion chamber from top(head) as well as from bottom(neck) of the phantom, henceforth measurement done at two different positions simultaneously. Leksell frame fixed to phantom simulated patient treatment. Prior to dosimetric study, hounsfield units and electron density of acrylic material were incorporated into the calibration curve in the TPS for convolution algorithm calculation. A CT scan of phantom with ion chamber (PTW Freiberg, 0.125cc) was obtained with following scanning parameters: Tube voltage-110kV, Slice thickness-1mm and FOV-240mm. Three separate single shot plans were generated in LGP TPS (Version 10.1.) with collimators 16mm, 8mm and 4mm respectively for both ion chamber positions. Both TMR10 and Convolution algorithm based planning (CABP) were used for dose calculation. A dose of 6Gy at 100% isodose was prescribed at centre of ion chamber visible in the CT scan. The phantom with ion chamber was positioned in the treatment couch for dose delivery. Results: The ion chamber measured dose was 5.98Gy for 16mm collimator shot plan with less than 1% deviation for convolution algorithm whereas with TMR10 measured dose was 5.6Gy. For 8mm and 4mm collimator plan merely a dose of 3.86Gy and 2.18Gy respectively were delivered at TPS calculated time for CABP. Conclusion: CABP is expected to perform accurate prediction of time for dose delivery for all collimators, but significant variation in measured dose was observed for 8mm and 4mm collimator which may be due collimator size effect. Effect of metal artifacts caused by pins and frame on the CT scan also may have role in misinterpreting CABP. The study carried out requires further investigation.

  15. SU-E-T-563: Multi-Fraction Stereotactic Radiosurgery with Extend System of Gamma Knife: Treatment Verification Using Indigenously Designed Patient Simulating Multipurpose Phantom

    SciTech Connect

    Bisht, R; Kale, S; Gopishankar, N; Rath, G; Julka, P; Agarwal, D; Singh, M; Garg, A; Kumar, P; Thulkar, S; Sharma, B

    2015-06-15

    Purpose: Aim of the study is to evaluate mechanical and radiological accuracy of multi-fraction regimen and validate Gamma knife based fractionation using newly developed patient simulating multipurpose phantom. Methods: A patient simulating phantom was designed to verify fractionated treatments with extend system (ES) of Gamma Knife however it could be used to validate other radiotherapy procedures as well. The phantom has options to insert various density material plugs and mini CT/MR distortion phantoms to analyze the quality of stereotactic imaging. An additional thorax part designed to predict surface doses at various organ sites. The phantom was positioned using vacuum head cushion and patient control unit for imaging and treatment. The repositioning check tool (RCT) was used to predict phantom positioning under ES assembly. The phantom with special inserts for film in axial, coronal and sagittal plane were scanned with X-Ray CT and the acquired images were transferred to treatment planning system (LGP 10.1). The focal precession test was performed with 4mm collimator and an experimental plan of four 16mm collimator shots was prepared for treatment verification of multi-fraction regimen. The prescription dose of 5Gy per fraction was delivered in four fractions. Each fraction was analyzed using EBT3 films scanned with EPSON 10000XL Scanner. Results: The measurement of 38 RCT points showed an overall positional accuracy of 0.28mm. The mean deviation of 0.28% and 0.31 % were calculated as CT and MR image distortion respectively. The radiological focus accuracy test showed its deviation from mechanical center point of 0.22mm. The profile measurement showed close agreement between TPS planned and film measured dose. At tolerance criteria of 1%/1mm gamma index analysis showed a pass rate of > 95%. Conclusion: Our results show that the newly developed multipurpose patient simulating phantom is highly suitable for the verification of fractionated stereotactic

  16. SU-E-J-240: The Impact On Clinical Dose-Distributions When Using MR-Images Registered with Stereotactic CT-Images in Gamma Knife Radiosurgery

    SciTech Connect

    Benmakhlouf, H; Kraepelien, T; Forander, P; Wangerid, T

    2014-06-01

    Purpose: Most Gamma knife treatments are based solely on MR-images. However, for fractionated treatments and to implement TPS dose calculations that require electron densities, CT image data is essential. The purpose of this work is to assess the dosimetric effects of using MR-images registered with stereotactic CT-images in Gamma knife treatments. Methods: Twelve patients treated for vestibular schwannoma with Gamma Knife Perfexion (Elekta Instruments, Sweden) were selected for this study. The prescribed doses (12 Gy to periphery) were delivered based on the conventional approach of using stereotactic MR-images only. These plans were imported into stereotactic CT-images (by registering MR-images with stereotactic CT-images using the Leksell gamma plan registration software). The dose plans, for each patient, are identical in both cases except for potential rotations and translations resulting from the registration. The impact of the registrations was assessed by an algorithm written in Matlab. The algorithm compares the dose-distributions voxel-by-voxel between the two plans, calculates the full dose coverage of the target (treated in the conventional approach) achieved by the CT-based plan, and calculates the minimum dose delivered to the target (treated in the conventional approach) achieved by the CT-based plan. Results: The mean dose difference between the plans was 0.2 Gy to 0.4 Gy (max 4.5 Gy) whereas between 89% and 97% of the target (treated in the conventional approach) received the prescribed dose, by the CT-plan. The minimum dose to the target (treated in the conventional approach) given by the CT-based plan was between 7.9 Gy and 10.7 Gy (compared to 12 Gy in the conventional treatment). Conclusion: The impact of using MR-images registered with stereotactic CT-images has successfully been compared to conventionally delivered dose plans showing significant differences between the two. Although CTimages have been implemented clinically; the effect of the

  17. Time-resolved imaging of prompt-gamma rays for proton range verification using a knife-edge slit camera based on digital photon counters.

    PubMed

    Cambraia Lopes, Patricia; Clementel, Enrico; Crespo, Paulo; Henrotin, Sebastien; Huizenga, Jan; Janssens, Guillaume; Parodi, Katia; Prieels, Damien; Roellinghoff, Frauke; Smeets, Julien; Stichelbaut, Frederic; Schaart, Dennis R

    2015-08-01

    Proton range monitoring may facilitate online adaptive proton therapy and improve treatment outcomes. Imaging of proton-induced prompt gamma (PG) rays using a knife-edge slit collimator is currently under investigation as a potential tool for real-time proton range monitoring. A major challenge in collimated PG imaging is the suppression of neutron-induced background counts. In this work, we present an initial performance test of two knife-edge slit camera prototypes based on arrays of digital photon counters (DPCs). PG profiles emitted from a PMMA target upon irradiation with a 160 MeV proton pencil beams (about 6.5 × 10(9) protons delivered in total) were measured using detector modules equipped with four DPC arrays coupled to BGO or LYSO : Ce crystal matrices. The knife-edge slit collimator and detector module were placed at 15 cm and 30 cm from the beam axis, respectively, in all cases. The use of LYSO : Ce enabled time-of-flight (TOF) rejection of background events, by synchronizing the DPC readout electronics with the 106 MHz radiofrequency signal of the cyclotron. The signal-to-background (S/B) ratio of 1.6 obtained with a 1.5 ns TOF window and a 3 MeV-7 MeV energy window was about 3 times higher than that obtained with the same detector module without TOF discrimination and 2 times higher than the S/B ratio obtained with the BGO module. Even 1 mm shifts of the Bragg peak position translated into clear and consistent shifts of the PG profile if TOF discrimination was applied, for a total number of protons as low as about 6.5 × 10(8) and a detector surface of 6.6 cm × 6.6 cm. PMID:26216269

  18. Stereotactic Radiosurgery - Gamma Knife

    MedlinePlus

    ... nerve that connects the ear to the brain ( acoustic neuroma ) Pituitary tumors Tumors that are not cancer ( ... A.M. Editorial team. Related MedlinePlus Health Topics Acoustic Neuroma Brain Tumors Radiation Therapy Browse the Encyclopedia ...

  19. Target and peripheral dose from radiation sector motions accompanying couch repositioning of patient coordinates with the Gamma Knife® Perfexion™

    PubMed Central

    Tran, Tuan-Anh; Wu, Vincent; Malhotra, Harish; Steinman, James P.; Prasad, Dheerendra; Podgorsak, Matthew B.

    2011-01-01

    Background The GammaPlan™ treatment planning system (TPS) does not fully account for shutter dose when multiple shots are required to deliver a patient’s treatment. The unaccounted exposures to the target site and its periphery are measured in this study. The collected data are compared to a similar effect from the Gamma Knife® model 4C. Materials and methods. A stereotactic head frame was attached to a Leksell® 16 cm diameter spherical phantom; using a fiducial-box, CT images of the phantom were acquired and registered in the TPS. Measurements give the relationship of measured dose to the number of repositions with the patient positioning system (PPS) and to the collimator size. An absorbed dose of 10 Gy to the 50% isodose line was prescribed to the target site and all measurements were acquired with an ionization chamber. Results Measured dose increases with frequency of repositioning and with collimator size. As the radiation sectors transition between the beam on and beam off states, the target receives more shutter dose than the periphery. Shutter doses of 3.53±0.04 and 1.59±0.04 cGy/reposition to the target site are observed for the 16 and 8 mm collimators, respectively. The target periphery receives additional dose that varies depending on its position relative to the target. Conclusions The radiation sector motions for the Gamma Knife® Perfexion™ result in an additional dose due to the shutter effect. The magnitude of this exposure is comparable to that measured for the model 4C. PMID:22933947

  20. SU-E-E-15: Design of a Water Calorimeter for Dual Use in An Integrated MRI-Linac and Gamma-Knife

    SciTech Connect

    Entezari, N; Renaud, J; Ly, D; Sarfehnia, A

    2015-06-15

    Purpose: To design a water calorimeter for dual use in an integrated MRI-linac and Gamma-Knife. In calorimetry, dose to water is measured based on the assumption that energy absorbed in a sensitive volume is completely converted to temperature rise {sub (}ΔΤ{sub )} according to the specific heat capacity of the medium c: D=c*ΔT*k, where k is heat transfer correction factor and compensates for heat gain or loss at point of measurement due to conductive effects. Methods: A commercial finite element method software package was used to model four different water calorimeter designs. The long term (48 h) thermal stability of each design was accurately modeled, and the optimization of the final design was based on evaluation of the standard deviation of k for ten consecutive irradiation runs (lower standard deviation translates to greater thermal stability). Several insulator materials of varying thicknesses were investigated, and a sensitivity study of thermal stability to variations in ambient temperature fluctuations was undertaken. Specifically, we evaluated the effect of possible variations in coolant temperature circulating around the calorimeter tank in several scenarios (constant, slowly increasing, or fluctuating). Results: Due to MRI-compatibility requirements, the calorimeter is to be built entirely out of plastic. Among all insulation materials tested, solid state aerogel-based insulation resulted in least heat loss and thermal stability. The final design is cylindrical on top (to be used upright in MRI-linac) and semi-spherical at bottom (for use in GammaKnife). The range of k was found to be 1.002 ± 0.013 (k = 1), comparable with a k of 1.002 ± 0.014 for typical water calorimeters used in high energy beams. A long term stability of 0.36 µK/hr was evaluated. Conclusion: Optimization of a water calorimeter design for dual use in MRI-linac and Gamma-Knife has been completed and the device is currently in production. Supported by NSERC RGPIN 435608.

  1. Changing practice patterns of Gamma Knife versus linear accelerator-based stereotactic radiosurgery for brain metastases in the US.

    PubMed

    Park, Henry S; Wang, Elyn H; Rutter, Charles E; Corso, Christopher D; Chiang, Veronica L; Yu, James B

    2016-04-01

    OBJECT Single-fraction stereotactic radiosurgery (SRS) is a crucial component in the management of limited brain metastases from non-small cell lung cancer (NSCLC). Intracranial SRS has traditionally been delivered using a frame-based Gamma Knife (GK) platform, but stereotactic modifications to the linear accelerator (LINAC) have made an alternative approach possible. In the absence of definitive prospective trials comparing the efficacy and toxicities of treatment between the 2 techniques, nonclinical factors (such as technology accessibility, costs, and efficiency) may play a larger role in determining which radiosurgery system a facility may choose to install. To the authors' knowledge, this study is the first to investigate national patterns of GK SRS versus LINAC SRS use and to determine which factors may be associated with the adoption of these radiosurgery systems. METHODS The National Cancer Data Base was used to identify patients > 18 years old with NSCLC who were treated with single-fraction SRS to the brain between 2003 and 2011. Patients who received "SRS not otherwise specified" or who did not receive a radiotherapy dose within the range of 12-24 Gy were excluded to reduce the potential for misclassification. The chi-square test, t-test, and multivariable logistic regression analysis were used to compare potential demographic, clinicopathologic, and health care system predictors of GK versus LINAC SRS use, when appropriate. RESULTS This study included 1780 patients, among whom 1371 (77.0%) received GK SRS and 409 (23.0%) underwent LINAC SRS. Over time, the proportion of patients undergoing LINAC SRS steadily increased, from 3.2% in 2003 to 30.8% in 2011 (p < 0.001). LINAC SRS was adopted more rapidly by community versus academic facilities (overall 29.2% vs 17.2%, p < 0.001). On multivariable analysis, 4 independent predictors of increased LINAC SRS use emerged, including year of diagnosis in 2008-2011 versus 2003-2007 (adjusted OR [AOR] 2.04, 95% CI 1

  2. Long-term stability of the Leksell Gamma Knife{sup ®} Perfexion™ patient positioning system (PPS)

    SciTech Connect

    Novotny, J.; Bhatnagar, J. P.; Xu, Y.; Huq, M. S.

    2014-03-15

    Purpose: To assess the long-term mechanical stability and accuracy of the patient positioning system (PPS) of the Leksell Gamma Knife{sup ®} Perfexion™ (LGK PFX). Methods: The mechanical stability of the PPS of the LGK PFX was evaluated using measurements obtained between September 2007 and June 2011. Three methods were employed to measure the deviation of the coincidence of the radiological focus point (RFP) and the PPS calibration center point (CCP). In the first method, the onsite diode test tool with single diode detector was used together with the 4 mm collimator on a daily basis. In the second method, a service diode test tool with three diode detectors was used biannually at the time of the routine preventive maintenance. The test performed with the service diode test tool measured the deviations for all three collimators 4, 8, and 16 mm and also for three different positions of the PPS. The third method employed the conventional film pin-prick method. This test was performed annually for the 4 mm collimator at the time of the routine annual QA. To estimate the effect of the patient weight on the performance of the PPS, the focus precision tests were also conducted with varying weights on the PPS using a set of lead bricks. Results: The average deviations measured from the 641 daily focus precision tests were 0.1 ± 0.1, 0.0 ± 0.0, and 0.0 ± 0.0 mm, respectively, for the 4 mm collimator in the X (left/right of the patient), Y (anterior/posterior of the patient), and Z (superior/inferior of the patient) directions. The average of the total radial deviations as measured during ten semiannual measurements with the service diode test tool were 0.070 ± 0.029, 0.060 ± 0.022, and 0.103 ± 0.028 mm, respectively for the central, long, and short diodes for the 4 mm collimator. Similarly, the average total radial deviations measured during the semiannual measurements for the 4, 8, and 16 mm collimators and using the central diode were 0.070 ± 0.029, 0.097 ± 0

  3. Dosimetric characteristics and quality control tests for the collimator sectors of the Leksell Gamma Knife Perfexion{sup TM}

    SciTech Connect

    Bhatnagar, Jagdish P.; Novotny, Josef Jr.; Saiful Huq, M.

    2012-01-15

    Purpose: The purpose of this study was to evaluate the dosimetric characteristics of each sector of the Leksell Gamma Knife Perfexion (LGK PFX) and to develop tests that can be done for the routine quality assurance checks of the sectors of the LGK PFX. Methods: The following tests were performed to evaluate the dosimetric characteristics of the sectors: (1) Flash-radiation dose for the 16 mm collimator, (2) transit-radiation dose for the 8 and 4 mm collimators, (3) sector leakage within the radiation cavity and, (4) sector output uniformity. In these tests, the Elekta ABS phantom was used. A micropoint ion-chamber Exradin A16 was placed at the center of the phantom for all measurements. Results: With the version 8.0 of the control software of the MCU in the LGK PFX, the average flash-radiation dose per sector for the 16 mm collimator was measured to be 0.423 {+-} 0.003 cGy, and the average transit-radiation dose per sector for the 8 and 4 mm collimators was measured to be 0.169 {+-} 0.0009 and 0.147 {+-} 0.020 cGy, respectively. The calibration dose rate on the day of measurements was 280.8 cGy/min. Here, the authors have introduced a new concept of ''equivalent-time-duration'' (ETD) to represent the time duration, during which the flash-radiation or the transit-radiation dose is delivered. The ETD is a quotient of the measured dose of the flash-radiation or the transit-radiation and the respective calibrated dose rate for the 16, 8, or 4 mm collimator. The ETD constancy is an indicator of the constancy of the sector movements. The average value of ETD per sector was measured to be 724 {+-} 6, 313 {+-} 2, and 311 {+-} 45 ms for the 16, 8, and 4 mm collimators, respectively. During monthly spot checks, the authors have been measuring the total ETD for the flash-radiation when all eight sectors are open with the 16 mm collimator. The average value of the total ETD of the last 40 consecutive months was measured to be 642 {+-} 10 ms. This number is a useful quality

  4. Real-time prompt gamma monitoring in spot-scanning proton therapy using imaging through a knife-edge-shaped slit

    NASA Astrophysics Data System (ADS)

    Bom, Victor; Joulaeizadeh, Leila; Beekman, Freek

    2012-01-01

    In this paper we report on Monte Carlo simulations to investigate real-time monitoring of the track depth profile in particle therapy by measuring prompt gamma ray emissions: a high sensitivity imaging system employing a knife-edge-shaped slit combined with a position-sensitive gamma detector was evaluated. Calculations to test this new concept were performed for a head-sized software phantom. Clear spatial correlation is shown between the distribution of gamma rays detected with energies above 1.5 MeV and the distribution of prompt gamma rays emitted from the phantom. The number of neutrons originating from nuclear reactions in the phantom that are detected at these high energies is small. Most importantly it is shown that under common therapy conditions enough data may be collected during one spot-step (of the order of 10 ms) to locate the distal dose edge with a 1σ accuracy of better than 1 mm. This indicates that simple slit cameras have high potential for accurate real-time particle therapy adjustment and may become a practical way to improve particle therapy accuracy.

  5. Gamma Knife radiosurgery for cerebral arteriovenous malformations in children/adolescents and adults. Part II: Differences in obliteration rates, treatment-obliteration intervals, and prognostic factors

    SciTech Connect

    Nicolato, Antonio . E-mail: antonio.nicolato@mail.azosp.vr.it; Lupidi, Francesco; Sandri, Marco F. Dr. Econom.; Foroni, Roberto; Zampieri, Piergiuseppe; Mazza, Carlo; Pasqualin, Alberto; Beltramello, Alberto; Gerosa, Massimo

    2006-03-01

    Purpose: To evaluate and compare obliteration rates (OBRs) and treatment-obliteration intervals (TOIs) for cerebral arteriovenous malformations (cAVMs) treated with Gamma Knife radiosurgery in children/adolescents and adults; and to determine factors predicting the OBR and TOI in these two populations. Methods and Materials: This study concerned 62 children/adolescents and 193 adults observed for {>=}3 years. Fisher exact two-tailed and Wilcoxon rank-sum tests, multiple logistics, and Cox proportional hazard models were used for statistical analysis. Results: The overall OBR was 85.5% in children/adolescents and 87.6% in adults (p 0.671), but children/adolescents showed higher 36-month actuarial OBRs (69.35%) and shorter median TOIs (25.7 months) than adults (66.84% and 28.2 months; p 0.006 and p = 0.017, respectively). In children/adolescents, lower Spetzler-Martin grades (p = 0.043) and younger age (p = 0.019) correlated significantly with OBRs, and lower Spetzler-Martin grades (p 0.024) and noneloquent cAVM locations (p = 0.046) with TOIs. In adults, low flow through the cAVM and <6.2-cm{sup 3} volume were associated with both OBR and TOI (p 0.012 and p = 0.002, respectively). Conclusions: The differences in OBRs within 3 years and TOIs, although slight, seem to show that pediatric cAVMs behave differently from those in adults after Gamma Knife radiosurgery.

  6. Time-resolved imaging of prompt-gamma rays for proton range verification using a knife-edge slit camera based on digital photon counters

    NASA Astrophysics Data System (ADS)

    Cambraia Lopes, Patricia; Clementel, Enrico; Crespo, Paulo; Henrotin, Sebastien; Huizenga, Jan; Janssens, Guillaume; Parodi, Katia; Prieels, Damien; Roellinghoff, Frauke; Smeets, Julien; Stichelbaut, Frederic; Schaart, Dennis R.

    2015-08-01

    Proton range monitoring may facilitate online adaptive proton therapy and improve treatment outcomes. Imaging of proton-induced prompt gamma (PG) rays using a knife-edge slit collimator is currently under investigation as a potential tool for real-time proton range monitoring. A major challenge in collimated PG imaging is the suppression of neutron-induced background counts. In this work, we present an initial performance test of two knife-edge slit camera prototypes based on arrays of digital photon counters (DPCs). PG profiles emitted from a PMMA target upon irradiation with a 160 MeV proton pencil beams (about 6.5   ×   109 protons delivered in total) were measured using detector modules equipped with four DPC arrays coupled to BGO or LYSO : Ce crystal matrices. The knife-edge slit collimator and detector module were placed at 15 cm and 30 cm from the beam axis, respectively, in all cases. The use of LYSO : Ce enabled time-of-flight (TOF) rejection of background events, by synchronizing the DPC readout electronics with the 106 MHz radiofrequency signal of the cyclotron. The signal-to-background (S/B) ratio of 1.6 obtained with a 1.5 ns TOF window and a 3 MeV-7 MeV energy window was about 3 times higher than that obtained with the same detector module without TOF discrimination and 2 times higher than the S/B ratio obtained with the BGO module. Even 1 mm shifts of the Bragg peak position translated into clear and consistent shifts of the PG profile if TOF discrimination was applied, for a total number of protons as low as about 6.5   ×   108 and a detector surface of 6.6 cm  ×  6.6 cm.

  7. Feasibility of a wireless gamma probe in radioguided surgery

    NASA Astrophysics Data System (ADS)

    Park, Hye Min; Joo, Koan Sik

    2016-06-01

    Radioguided surgery through the use of a gamma probe is an established practice, and has been widely applied in the case of sentinel lymph node biopsies. A wide range of intraoperative gamma probes is commercially available. The primary characteristics of the gamma probes include their sensitivity, spatial resolution, and energy resolution. We present the results obtained from a prototype of a new wireless gamma probe. This prototype is composed of a 20 mm thick cerium-doped gadolinium aluminum gallium garnet (Ce:GAGG) inorganic scintillation crystal from Furukawa Denshi and a Hamamatsu S12572-100C multi-pixel photon counter equipped with a designed electronics. The measured performance characteristics include the energy resolution, energy linearity, angular aperture, spatial resolution and sensitivity. Measurements were carried out using 57Co, 133Ba, 22Na, and 137Cs sources. The energy resolutions for 0.122 and 0.511 MeV were 17.2% and 6.9%, respectively. The designed prototype consumes an energy of approximately 4.4 W, weighs about 310 g (including battery) having a dimension of 20 mm (D)  ×  130 mm (L).

  8. Feasibility of a wireless gamma probe in radioguided surgery.

    PubMed

    Park, Hye Min; Joo, Koan Sik

    2016-06-21

    Radioguided surgery through the use of a gamma probe is an established practice, and has been widely applied in the case of sentinel lymph node biopsies. A wide range of intraoperative gamma probes is commercially available. The primary characteristics of the gamma probes include their sensitivity, spatial resolution, and energy resolution. We present the results obtained from a prototype of a new wireless gamma probe. This prototype is composed of a 20 mm thick cerium-doped gadolinium aluminum gallium garnet (Ce:GAGG) inorganic scintillation crystal from Furukawa Denshi and a Hamamatsu S12572-100C multi-pixel photon counter equipped with a designed electronics. The measured performance characteristics include the energy resolution, energy linearity, angular aperture, spatial resolution and sensitivity. Measurements were carried out using (57)Co, (133)Ba, (22)Na, and (137)Cs sources. The energy resolutions for 0.122 and 0.511 MeV were 17.2% and 6.9%, respectively. The designed prototype consumes an energy of approximately 4.4 W, weighs about 310 g (including battery) having a dimension of 20 mm (D)  ×  130 mm (L). PMID:27245331

  9. Preliminary Evaluation of a Novel Thermoplastic Mask System with Intra-fraction Motion Monitoring for Future Use with Image-Guided Gamma Knife

    PubMed Central

    Bootsma, Gregory; Von Schultz, Oscar; Carlsson, Per; Laperriere, Normand; Millar, Barbara-Ann; Jaffray, David; Chung, Caroline

    2016-01-01

    Objectives  A non-invasive immobilization system consisting of a thermoplastic mask with image-guidance using cone-beam CT (CBCT) and infrared (IR) tracking has been developed to ensure minimal inter- and intra-fractional movement during Gamma Knife radiosurgery. Prior to clinical use for patients on a Gamma Knife, this study clinically evaluates the accuracy and stability of this novel immobilization system with image-guidance in patients treated with standard fractionated radiation therapy on a linear accelerator. Materials & methods This prospective cohort study evaluated adult patients planned for fractionated brain radiotherapy. Patients were immobilized with a thermoplastic mask (with the nose cut out) and customized head cushion. A reflective marker was placed on the patient’s nose tip and tracked with a stereoscopic IR camera throughout treatment. For each fraction, a pre-treatment, verification (after any translational correction for inter-fraction set-up variation), and post-treatment CBCT was acquired to evaluate inter- and intra-fraction movement of the target and nose. Intra-fraction motion of the nose tip measured on CBCT and IR tracking were compared. Results  Corresponding data from 123 CBCT and IR datasets from six patients are summarized. The mean ± standard deviation (SD) intra-fraction motion of the nose tip was 0.41±0.36 mm based on pre- and post-treatment CBCT data compared with 0.56±0.51 mm using IR tracking. The maximum intra-fraction motion of the nose tip was 1.7 mm using CBCT and 3.2 mm using IR tracking. The mean ± SD intra-fraction motion of the target was 0.34±0.25 mm, and the maximum intra-fraction motion was 1.5 mm. Conclusions: This initial clinical evaluation of the thermoplastic mask immobilization system using both IR tracking and CBCT demonstrate that mean intra-fraction motion of the nose and target is small. The presence of isolated measures of larger intra-fraction motion supports the need for image-guidance and

  10. Simulational study of a dosimetric comparison between a Gamma Knife treatment plan and an intensity-modulated radiotherapy plan for skull base tumors

    PubMed Central

    Nakazawa, Hisato; Mori, Yoshimasa; Komori, Masataka; Tsugawa, Takahiko; Shibamoto, Yuta; Kobayashi, Tatsuya; Hashizume, Chisa; Uchiyama, Yukio; Hagiwara, Masahiro

    2014-01-01

    Fractionated stereotactic radiotherapy (SRT) is performed with a linear accelerator-based system such as Novalis. Recently, Gamma Knife Perfexion (PFX) featured the Extend system with relocatable fixation devices available for SRT. In this study, the dosimetric results of these two modalities were compared from the viewpoint of conformity, heterogeneity and gradient in target covering. A total of 14 patients with skull base tumors were treated with Novalis intensity-modulated (IM)-SRT. Treatment was planned on an iPlan workstation. Five- to seven-beam IM-SRT was performed in 14–18 fractions with a fraction dose of 2.5 or 3 Gy. With these patients' data, additional treatment planning was simulated using a GammaPlan workstation for PFX-SRT. Reference CT images with planning structure contour sets on iPlan, including the planning target volume (PTV, 1.1–102.2 ml) and organs at risk, were exported to GammaPlan in DICOM-RT format. Dosimetric results for Novalis IM-SRT and PFX-SRT were evaluated in the same prescription doses. The isocenter number of PFX was between 12 and 50 at the isodose contour of 50–60%. The PTV coverage was 95–99% for Novalis and 94–98% for PFX. The conformity index (CI) was 1.11–1.61 and 1.04–1.15, the homogeneity index (HI) was 1.1–3.62 and 2.3–3.25, and the gradient index (GI) was 3.72–7.97 and 2.54–3.39 for Novalis and PFX, respectively. PTV coverage by Novalis and PFX was almost equivalent. PFX was superior in CI and GI, and Novalis was better in HI. Better conformality would be achieved by PFX, when the homogeneity inside tumors is less important. PMID:24351459

  11. Assessment of radiochromic gel dosimeter based on Turnbull Blue dye for relative output factor measurements of the Leksell Gamma Knife® PerfexionTM

    NASA Astrophysics Data System (ADS)

    Kozubikova, P.; Solc, J.; Novotny, J., Jr.; Pilarova, K.; Pipek, J.; Koncekova, J.

    2015-01-01

    The aim of the study was to perform assessment of radiochromic gel dosimeter based on Turnbull blue dye formed by irradiation (TB gel dosimeter) for measurement of ROFs for 4 mm and 8 mm collimators for the Leksell Gamma Knife PerfexionTM. All measurements have been carried out using home-made spherical Perspex glass phantom of diameter 160 mm. TB gel dosimeters were scanned using homemade optical CT scanner. The results are compared with vendor recommended Monte Carlo calculated ROFs values of 0.814 and 0.900 for 4 mm and 8 mm collimators, respectively. The comparisons between the gel measurements and the treatment planning system (TPS) calculation are presented in the form of 2D isodoses for the central slices and 1D profile. Measured ROF 0.746 and 0.874 for 4 mm and 8 mm collimators respectively are in a reasonable agreement with vendor recommended values and measured relative dose distribution in a central slice and measured profiles of all shots show excellent correspondence with TPS.

  12. Treating Mycobacterium ulcerans disease (Buruli ulcer): from surgery to antibiotics, is the pill mightier than the knife?

    PubMed Central

    Converse, Paul J; Nuermberger, Eric L; Almeida, Deepak V; Grosset, Jacques H

    2011-01-01

    Until 2004, the skin disease known as Buruli ulcer, caused by Mycobacterium ulcerans, could only be treated by surgery and skin grafting. Although this worked reasonably well on early lesions typically found in patients in Australia, the strategy was usually impractical on large lesions resulting from diagnostic delay in patients in rural West Africa. Based on promising preclinical studies, treatment trials in West Africa have shown that a combination of rifampin and streptomycin administered daily for 8 weeks can kill M. ulcerans bacilli, arrest the disease, and promote healing without relapse or reduce the extent of surgical excision. Improved treatment options are the focus of research that has increased tremendously since the WHO began its Global Buruli Ulcer Initiative in 1998. PMID:22004037

  13. Utilization of Cone-Beam Computed Tomographic Angiography in Planning for Gamma Knife Radiosurgery of Arteriovenous Malformations: A Case Series and Early Report

    PubMed Central

    Safain, Mina G.; Rahal, Jason P.; Raval, Ami; Rivard, Mark J.; Mignano, John; Wu, Julian; Malek, Adel M.

    2014-01-01

    Background The effectiveness of Gamma Knife radiosurgery (GKR) for cerebral arteriovenous malformations (AVM) is predicated on inclusion of the entire nidus while excluding normal tissue. As such, GKR may be limited by the resolution and accuracy of the imaging modality used in targeting. Objective We present the first case series to demonstrate the feasibility of utilizing ultra-high-resolution C-arm cone beam computed tomography angiography (CBCT-A) in AVM targeting. Methods From June 2009 to June 2013, CBCT-A was utilized for targeting of all patients with AVMs treated with GKR at our institution. Patients underwent Leksell stereotactic head frame placement followed by catheter-based biplane 2-D digital subtraction angiography (DSA), 3-D rotational angiography (3DRA), as well as CBCT-A. The CBCT-A dataset was used for stereotactic planning for GKR. Patients were followed up at 1, 3, 6, and 12 months, and then annually thereafter. Results CBCT-A-based targeting was used in twenty-two consecutive patients. CBCT-A provided detailed spatial resolution and sensitivity of nidal angioarchitecture enabling treatment. The average radiation dose to the margin of the AVM nidus corresponding to the 50% percent isodose line was 15.6 Gy. No patient had treatment-associated hemorrhage. At early follow-up (mean=16 months), 84% of patients had a decreasing or obliterated AVM nidus. Conclusion CBCT-A-guided radiosurgery is feasible and useful because it provides sufficient detailed resolution and sensitivity for imaging brain AVMs. PMID:24584136

  14. Clinical Outcomes of Gamma Knife Radiosurgery for Metastatic Brain Tumors from Gynecologic Cancer : Prognostic Factors in Local Treatment Failure and Survival

    PubMed Central

    Shin, Hong Kyung; Kim, Jeong Hoon; Lee, Do Heui; Cho, Young Hyun; Roh, Sung Woo

    2016-01-01

    Objective Brain metastases in gynecologic cancer (ovarian, endometrial, and cervical cancer) patients are rare, and the efficacy of Gamma Knife Radiosurgery (GKRS) to treat these had not been evaluated. We assessed the efficacy of GKRS and prognostic factors for tumor control and survival in brain metastasis from gynecologic cancers. Methods This retrospective study was approved by the institutional review board. From May 1995 to October 2012, 26 women (mean age 51.3 years, range 27–70 years) with metastatic brain tumors from gynecologic cancer were treated with GKRS. We reviewed their outcomes, radiological responses, and clinical status. Results In total 24 patients (59 lesions) were available for follow-up imaging. The median follow-up time was 9 months. The mean treated tumor volume at the time of GKRS was 8185 mm3 (range 10–19500 mm3), and the median dose delivered to the tumor margin was 25 Gy (range, 10–30 Gy). A local tumor control rate was 89.8% (53 of 59 tumors). The median overall survival was 9.5 months after GKRS (range, 1–102 months). Age-associated multivariate analysis indicated that the Karnofsky performance status (KPS), the recursive partitioning analysis (RPA) classification, and the number of treated lesions were significant prognostic factors for overall survival (HR=0.162, p=0.008, HR=0.107, p=0.038, and HR=2.897, p=0.045, respectively). Conclusion GKRS is safe and effective for the management of brain metastasis from gynecologic cancers. The clinical status of the patient is important in determining the overall survival time. PMID:27446522

  15. Gamma Knife radiosurgery for vestibular schwannomas: evaluation of tumor control and its predictors in a large patient cohort in The Netherlands.

    PubMed

    Klijn, Stijn; Verheul, Jeroen B; Beute, Guus N; Leenstra, Sieger; Mulder, Jef J S; Kunst, Henricus P M; Hanssens, Patrick E J

    2016-06-01

    OBJECT The authors of this study sought to assess tumor control and complication rates in a large cohort of patients who underwent Gamma Knife radiosurgery (GKRS) for vestibular schwannoma (VS) and to identify predictors of tumor control. METHODS The records of 420 patients treated with GKRS for VS with a median marginal dose of 11 Gy were retrospectively analyzed. Patients with neurofibromatosis Type 2 or who had undergone treatment for VS previously were excluded. The authors assessed tumor control and complication rates with chart review and used the Cox proportional hazards model to identify predictors of tumor control. Preservation of serviceable hearing, defined as Gardner-Robertson Class I-II, was evaluated in a subgroup of 71 patients with serviceable hearing at baseline and with available follow-up audiograms. RESULTS The median VS tumor volume was 1.4 cm(3), and the median length of follow-up was 5.1 years. Actuarial 5-and 10-year tumor control rates were 91.3% and 84.8%, respectively. Only tumor volume was a statistically significant predictor of tumor control rate. The tumor control rate decreased from 94.1% for tumors smaller than 0.5 cm(3) to 80.7% for tumors larger than 6 cm(3). Thirteen patients (3.1%) had new or increased permanent trigeminal nerve neuropathy, 4 (1.0%) had new or increased permanent facial weakness, and 5 (1.2%) exhibited new or increased hydrocephalus requiring a shunting procedure. Actuarial 3-year and 5-year hearing preservation rates were 65% and 42%, respectively. CONCLUSIONS The 5-year actuarial tumor control rate of 91.3% in this cohort of patients with VS compared slightly unfavorably with the rates reported in other large studies, but the complication and hearing preservation rates in this study were similar to those reported previously. Various factors may contribute to the observed differences in reported outcomes. These factors include variations in treatment indication and in the definition of treatment failure, as

  16. The Shoemaker's Knife

    ERIC Educational Resources Information Center

    Thomson, Ian

    2010-01-01

    Archimedes, the famous Greek mathematician, lived from 287 BCE until approximately 212 BCE. He thought that the figure of two semi-circles on a straight line enclosed by a larger semi-circle resembled a shoemaker's knife. Archimedes called this figure an "arbelos" since arbelos is the Greek word for a shoemaker's knife. The author describes the…

  17. A comprehensive overview of radioguided surgery using gamma detection probe technology

    PubMed Central

    Povoski, Stephen P; Neff, Ryan L; Mojzisik, Cathy M; O'Malley, David M; Hinkle, George H; Hall, Nathan C; Murrey, Douglas A; Knopp, Michael V; Martin, Edward W

    2009-01-01

    The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology. PMID:19173715

  18. Gamma Knife radiosurgery for cerebral arteriovenous malformations in children/adolescents and adults. Part I: Differences in epidemiologic, morphologic, and clinical characteristics, permanent complications, and bleeding in the latency period

    SciTech Connect

    Nicolato, Antonio . E-mail: antonio.nicolato@mail.azosp.vr.it; Lupidi, Francesco; Sandri, Marco F.; Foroni, Roberto; Zampieri, Piergiuseppe; Mazza, Carlo; Maluta, Sergio; Beltramello, Alberto; Gerosa, Massimo

    2006-03-01

    Purpose: To compare the epidemiologic, morphologic, and clinical characteristics of 92 children/adolescents (Group A) and 362 adults (Group B) with cerebral arteriovenous malformations (cAVMs) considered suitable for radiosurgery; to correlate radiosurgery-related permanent complication and post-radiosurgery bleeding rates in the 75 children/adolescents and 297 adults available for follow-up. Methods and Materials: Radiosurgery was performed with a model C 201-source Co{sup 6} Leksell Gamma Unit (Elekta Instruments, Stockholm, Sweden). Fisher exact two-tailed, Wilcoxon rank-sum, and two-sample binomial exact tests were used for statistical analysis. Results: There were significant differences between the two populations in sex (p = 0.015), clinical presentation (p = 0.001), and location (p = 0.008). The permanent complication rate was lower in younger (1.3%) than in older patients (5.4%), although the difference was not significant (p = 0.213). The postradiosurgery bleeding rate was lower in Group A (1.3%) than in Group B (2.7%) (p = 0.694), with global actuarial bleeding rates of 0.56% per year and 1.15% per year, respectively. Conclusions: The different characteristics of child/adolescent and adult cAVMs suggest that they should be considered two distinct vascular disorders. The similar rates of radiosurgery-related complications and latency period bleeding in the two populations show that gamma knife radiosurgery does not expose young patients to a higher risk of sequelae than that for older patients.

  19. The Knife Machine. Module 15.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This module on the knife machine, one in a series dealing with industrial sewing machines, their attachments, and operation, covers one topic: performing special operations on the knife machine (a single needle or multi-needle machine which sews and cuts at the same time). These components are provided: an introduction, directions, an objective,…

  20. Performance of a small CdTe gamma camera for radio-guided surgery

    NASA Astrophysics Data System (ADS)

    Tsuchimochi, Makoto; Sakahara, Harmui; Hayama, Kazuhide; Funaki, Minoru; Shirahata, T.; Orskaug, Terje; Maehlum, Gunnar; Yoshioka, Koki; Nygard, Einar

    2001-12-01

    Sentinel lymph node biopsy has been shown to be highly accurate for detecting metastatic diseases, such as melanoma and breast cancer. Gamma probes that measure only the relative presence of radioactivity are commonly used to identify sentinel lymph nodes. We have developed a small semiconductor gamma camera (SSGC) that allows the size, shape, and location of the target tissues to be visualized. The purpose of this study is to characterize the performance of the SSGC for radioguided surgery of metastatic lesions and for diagnosing other diseases amenable to the smaller- format associated with this prototype imaging system. Methods & Design: The detector head was comprised of a 32 x 32 Cadmium Telluride semiconductor array and application- specific integrated circuit (ASIC) with a tungsten collimator. The entire assembly was encased in a lead housing measuring 152 mm x 166 mm x 65 mm. The effective visual field was 44.8 mm x 44.8 mm. Two spherical 5 mm diameter Tc-99m radioactive sources having activities of 0.15 MBq and 100 MBq were used to simulate sentinel lymph nodes and injection site. The relative detectability of these foci was compared using the new detector and a conventional scintillation camera. Use of the prototype was also explored on patients in a variety of clinical applications. Results: the SSGC provided better spatial resolution on phantom studies than the conventional gamma camera control. Both foci could be visualized clearly by the SSGC using a 15 second acquisition time, whereas they could not be readily identified using the conventional system under comparable conditions. Preliminary clinical tests of the SSGC were found to be successful in imaging diseases in a variety of tissues including salivary and thyroid glands, temporomandibular joints, and sentinel lymph nodes. Conclusion: The SSGC has significant potential for use in diagnosing diseases and for facilitating subsequent radioguided surgery. (This project was supported by a Grant- in

  1. Stereotactic radiosurgery - CyberKnife

    MedlinePlus

    ... slides into a machine that delivers radiation. A robotic arm controlled by a computer moves around you. ... Accuray Incorporated. CyberKnife robotic radiosurgery system patient brochure. 2012. ... Accessed ...

  2. Peripheral dose measurement for CyberKnife radiosurgery with upgraded linac shielding.

    PubMed

    Chuang, Cynthia F; Larson, David A; Zytkovicz, Andrea; Smith, Vernon; Petti, Paula L

    2008-04-01

    The authors investigated the peripheral dose reduction for CyberKnife radiosurgery treatments after the installation of a linac shielding upgrade. As in a previous investigation, the authors considered two treatment plans, one for a hypothetical target in the brain and another for a target in the thorax, delivered to an anthropomorphic phantom. The results of the prior investigation showed that the CyberKnife delivered significantly higher peripheral doses than comparable model C Gamma Knife or IMRT treatments. Current measurements, after the linac shielding upgrade, demonstrate that the additional shielding decreased the peripheral dose, expressed as a percentage of the delivered monitor units (MU), by a maximum of 59%. The dose reduction was greatest for cranial-caudal distances from the field edge less than 30 cm, and at these distances, the CyberKnife peripheral dose, expressed as a percentage of the delivered MU, is now comparable to that measured for the other treatment modalities in our previous investigation. For distances between 30 and 70 cm from the field edge, the additional shielding reduced the peripheral dose by between 20% and 55%. At these distances, the CyberKnife peripheral dose remains higher than doses measured in our previous study for the model C Gamma Knife and IMRT. PMID:18491544

  3. Use of a handheld, semiconductor (cadmium zinc telluride)-based gamma camera in navigation surgery for primary hyperparathyroidism.

    PubMed

    Fujii, Takaaki; Yamaguchi, Satoru; Yajima, Reina; Tsutsumi, Soichi; Uchida, Nobuyuki; Asao, Takayuki; Oriuch, Noboru; Kuwano, Hiroyuki

    2011-06-01

    The recent development of gamma-ray probes makes it possible to perform radioguided surgery for primary hyperparathyroidism (PHPT). There have only been a few reports, however, regarding the use of a handheld gamma camera to detect parathyroid adenoma intraoperatively. The aim of this preliminary study was to assess the efficiency of a semiconductor gamma camera (eZ-SCOPE AN) in navigation surgery for PHPT. The eZ-SCOPE is designed to be used as a handheld, regional diagnostic imaging device. Eleven consecutive patients with documented primary hyperparathyroidism underwent surgery using this compact camera. Scintigraphy images of the neck by eZ-SCOPE were acquired: 1) before skin incision; 2) after adenoma location; 3) after adenoma excision; and 4) ex vivo imaging of the specimen. In scan-positive cases by preoperative Tc-MIBI, the eZ-SCOPE revealed parathyroid adenoma in all cases (100%), whereas ultrasound and CT showed a single adenoma in 63.6 and 72.7 per cent of cases, respectively. Navigation surgery for PHPT using the eZ-SCOPE permitted intraoperative identification and removal of parathyroid adenoma in all cases. Scintigraphy images of the neck by eZ-SCOPE also revealed a single adenoma even before skin incision. Our results suggest that Tc-MIBI scintigraphy with the eZ-SCOPE is useful for navigation surgery for PHPT. The eZ-SCOPE is useful for skin marking and could be easily applied for minimally invasive radioguided parathyroidectomy in scan-positive cases. PMID:21679634

  4. Comparison of O-Type HybridKnife to Conventional Knife in Endoscopic Submucosal Dissection for Gastric Mucosal Lesions.

    PubMed

    Huang, Rui; Yan, Honglin; Ren, Gui; Pan, Yanglin; Zhang, Linhui; Liu, Zhiguo; Guo, Xuegang; Wu, Kaichun

    2016-03-01

    Endoscopic submucosal dissection (ESD) has been accepted as a minimal invasive alternative to surgery for localized superficial gastrointestinal neoplasms recently. However, the procedure remains to be technically challenging and time consuming. A new dissecting knife with partially insulated tip has been recently developed with built-in injection capability. The purpose of this study was to investigate whether the efficiency of ESD procedure could be improved with this new device. A total of 78 patients, who underwent ESD with gastric mucosal lesions including flat type polyps, adenoma or early gastric cancer, were randomly assigned to either ESD with O-type HybridKnife or conventional ESD knives without waterjet. Procedure time and related factors of ESD were analyzed. ESD procedure time was 43.0 (interquartile range, IQR 27.0-60.0) minutes in HybridKnife group compared to 60.5 (IQR 44.0-86.3) minutes in the control group (P = 0.001). There was no difference in the clinical outcome and the adverse event rate. The former demonstrated more favorable results in lesions ≤4 cm of specimen size (P ≤ 0.0001) and when located in the distal stomach (P = 0.001), also in lesions with fibrosis (P = 0.008). Multivariate regression analysis showed that O-type Knife (P ≤ 0.0001), specimen size (P ≤ 0.0001), and fibrosis (P ≤ 0.0001) were independent predictors of procedure time. The O-type HybridKnife yielded faster procedure time compared to the conventional knives in gastric ESD with a similar safety profile. PMID:27043675

  5. Comparison of O-Type HybridKnife to Conventional Knife in Endoscopic Submucosal Dissection for Gastric Mucosal Lesions

    PubMed Central

    Huang, Rui; Yan, Honglin; Ren, Gui; Pan, Yanglin; Zhang, Linhui; Liu, Zhiguo; Guo, Xuegang; Wu, Kaichun

    2016-01-01

    Abstract Endoscopic submucosal dissection (ESD) has been accepted as a minimal invasive alternative to surgery for localized superficial gastrointestinal neoplasms recently. However, the procedure remains to be technically challenging and time consuming. A new dissecting knife with partially insulated tip has been recently developed with built-in injection capability. The purpose of this study was to investigate whether the efficiency of ESD procedure could be improved with this new device. A total of 78 patients, who underwent ESD with gastric mucosal lesions including flat type polyps, adenoma or early gastric cancer, were randomly assigned to either ESD with O-type HybridKnife or conventional ESD knives without waterjet. Procedure time and related factors of ESD were analyzed. ESD procedure time was 43.0 (interquartile range, IQR 27.0–60.0) minutes in HybridKnife group compared to 60.5 (IQR 44.0–86.3) minutes in the control group (P = 0.001). There was no difference in the clinical outcome and the adverse event rate. The former demonstrated more favorable results in lesions ≤4 cm of specimen size (P ≤ 0.0001) and when located in the distal stomach (P = 0.001), also in lesions with fibrosis (P = 0.008). Multivariate regression analysis showed that O-type Knife (P ≤ 0.0001), specimen size (P ≤ 0.0001), and fibrosis (P ≤ 0.0001) were independent predictors of procedure time. The O-type HybridKnife yielded faster procedure time compared to the conventional knives in gastric ESD with a similar safety profile. PMID:27043675

  6. Radioisotope guided surgery with imaging probe, a hand-held high-resolution gamma camera

    NASA Astrophysics Data System (ADS)

    Soluri, A.; Trotta, C.; Scopinaro, F.; Tofani, A.; D'Alessandria, C.; Pasta, V.; Stella, S.; Massari, R.

    2007-12-01

    Since 1997, our group of Physics together with Nuclear Physicians studies imaging probes (IP), hand-held, high-resolution gamma cameras for radio-guided surgery (RGS). Present work is aimed to verify the usefulness of two updated IP in different surgical operations. Forty patients scheduled for breast cancer sentinel node (SN) biopsy, five patients with nodal recurrence of thyroid cancer, seven patients with parathyroid adenomas, five patients with neuroendocrine tumours (NET), were operated under the guide of IP. We used two different IP with field of view of 1 and 4 in. 2, respectively and intrinsic spatial resolution of about 2 mm. Radioisotopes were 99mTc, 123I and 111In. The 1 in. 2 IP detected SN in all the 40 patients and more than one node in 24, whereas anger camera (AC) failed locating SN in four patients and detected true positive second nodes in only nine patients. The 4 in. 2 IP was used for RGS of thyroid, parathyroid and NETs. It detected eight latero-cervical nodes. In the same patients, AC detected five invaded nodes. Parathyroid adenomas detected by IP were 10 in 7 patients, NET five in five patients. One and 4 in. 2 IPs showed usefulness in all operations. Initial studies on SN biopsy were carried out on small series of patients to validate IP and to demonstrate the effectiveness and usefulness of IP alone or against conventional probes. We propose the use of the IP as control method for legal documentation and surgeon strategy guide before and after lesion(s) removal.

  7. Maintaining knife sharpness in industrial meat cutting: A matter of knife or meat cutter ability.

    PubMed

    Karltun, J; Vogel, K; Bergstrand, M; Eklund, J

    2016-09-01

    Knife sharpness is imperative in meat cutting. The aim of this study was to compare the impact of knife blade steel quality with meat cutters' individual ability to maintain the cutting edge sharp in an industrial production setting. Twelve meat cutters in two different companies using three different knives during normal production were studied in this quasi-experimental study. Methods included were measuring knife cutting force before and after knife use, time knives were used, ratings of sharpness and discomfort and interviews. Results showed that the meat cutters' skill of maintaining sharpness during work had a much larger effect on knife sharpness during work than the knife steel differences. The ability was also related to feelings of discomfort and to physical exertion. It was found that meat cutters using more knives were more likely to suffer from discomfort in the upper limbs, which is a risk for developing MSD. PMID:27184316

  8. Evaluation of holmium laser versus cold knife in optical internal urethrotomy for the management of short segment urethral stricture

    PubMed Central

    Jain, Sudhir Kumar; Kaza, Ram Chandra Murthy; Singh, Bipin Kumar

    2014-01-01

    Objectives: Sachse cold knife is conventionally used for optical internal urethrotomy intended to manage urethral strictures and Ho: YAG laser is an alternative to it. The aim of this study was to evaluate the role of urethral stricture treatment outcomes, efficacy, and complications using cold knife and Ho: YAG (Holmium laser) for optical internal urethrotomy Materials and Methods: In this prospective study included, 90 male patients age >18 years, with diagnosis of urethral stricture admitted for internal optical urethrotomy during April 2010 to March 2012. The patients were randomized into two groups containing 45 patients each using computer generated random number. In group A (Holmium group), internal urethrotomy was done with Holmium laser and in group B (Cold knife group) Sachse cold knife was used. Patients were followed up for 6 months after surgery in Out Patient Department on 15, 30 and 180 post-operative days. At each follow up visit physical examination, and uroflowmetry was performed along with noting complaints, if any. Results: The peak flow rates (PFR) were compared between the two groups on each follow up. At 180 days (6 month interval) the difference between mean of PFR for Holmium and Cold knife group was statistically highly significant (P < 0.001). Complications were seen in 12.22% of cases. Conclusion: Both modalities are effective in providing immediate relief to patients with single and short segment (<2 cm long) urethral strictures but more sustained response was attained with Cold knife urethrotomy. PMID:25371611

  9. A sharp knife for high temperatures

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.

    1978-01-01

    Electrically heated nickel-chrome-steel alloy knife may be used to cut heat resistant plastic felt and similar materials with relative ease. Blade made of commercially available alloy RA 330 retains edge at temperatures as high as 927 C.

  10. A qualitative analysis of acute care surgery in the United States: It’s more than just “a competent surgeon with a sharp knife and a willing attitude”

    PubMed Central

    Santry, Heena P.; Pringle, Patricia L.; Collins, Courtney E.; Kiefe, Catarina I.

    2014-01-01

    Background Since acute care surgery (ACS) was conceptualized a decade ago, the specialty has been adopted widely; however, little is known about the structure and function of ACS teams. Methods We conducted 18 open-ended interviews with ACS leaders (representing geographic [New England, Northeast, Mid-Atlantic, South, West, Midwest] and practice [Public/Charity, Community, University] diversity). Two independent reviewers analyzed transcribed interviews using an inductive approach (NVivo qualitative analysis software). Results All respondents described ACS as a specialty treating “time-sensitive surgical disease” including trauma, emergency general surgery (EGS), and surgical critical care (SCC); 11 of 18 combined trauma and EGS into a single clinical team; 9 of 18 included elective general surgery. Emergency orthopedics, emergency neurosurgery, and surgical subspecialty triage were rare (1/18 each). Eight of 18 ACS teams had scheduled EGS operating room time. All had a core group of trauma and SCC surgeons; 13 of 18 shared EGS due to volume, human resources, or competition for revenue. Only 12 of 18 had formal signout rounds; only 2 of 18 had prospective EGS data registries. Streamlined access to EGS, evidence-based protocols, and improved education were considered strengths of ACS. ACS was described as the “last great surgical service” reinvigorated to provide “timely,” cost-effective EGS by experts in “resuscitation and critical care” and to attract “young, talented, eager surgeons” to trauma/SCC; however, there was concern that ACS might become the “wastebasket for everything that happens at inconvenient times.” Conclusion Despite rapid adoption of ACS, its implementation varies widely. Standardization of scope of practice, continuity of care, and registry development may improve EGS outcomes and allow the specialty to thrive. (Surgery 2014;155:809-25.) PMID:24787108

  11. Stereotactic ablative radiotherapy with CyberKnife for advanced thymic carcinoma: a case report

    PubMed Central

    Fan, C.Y.; Huang, W.Y.; Jen, Y.M.; Lin, M.J.; Lin, K.T.

    2015-01-01

    Thymic carcinoma is a rare but lethal mediastinal cancer. The optimal treatment for advanced thymic carcinoma is not yet established. This report is the first known of stereotactic ablative radiotherapy (sabr) with CyberKnife (Accuray, Sunnyvale, CA, U.S.A.) as definitive therapy for thymic carcinoma. The patient, a 70-year-old woman with thymic carcinoma, invasion into neighboring organs, and pleural metastases—underwent CyberKnife sabr at 40 Gy in 5 fractions for two lesions, one in the thymus and one in the right paraspinal pleura. After 61 months of observation, a partial response was observed in the irradiated fields. However, disease progression in the non-irradiated pleura was noted. The patient underwent salvage CyberKnife sabr for the four initially nonirradiated pleural lesions. Computed tomography images obtained 10 months after the salvage therapy revealed a partial response. The patient is living, with progression-free irradiated lesions and no radiation-related toxicity. CyberKnife sabr is feasible for patients who are unable to undergo either surgery or conventionally fractionated radiation therapy. PMID:26628883

  12. 21 CFR 886.4230 - Ophthalmic knife test drum.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic knife test drum. 886.4230 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4230 Ophthalmic knife test drum. (a) Identification. An ophthalmic knife test drum is a device intended to test the keenness of ophthalmic...

  13. 21 CFR 886.4230 - Ophthalmic knife test drum.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic knife test drum. 886.4230 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4230 Ophthalmic knife test drum. (a) Identification. An ophthalmic knife test drum is a device intended to test the keenness of ophthalmic...

  14. 21 CFR 886.4230 - Ophthalmic knife test drum.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic knife test drum. 886.4230 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4230 Ophthalmic knife test drum. (a) Identification. An ophthalmic knife test drum is a device intended to test the keenness of ophthalmic...

  15. 21 CFR 886.4230 - Ophthalmic knife test drum.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic knife test drum. 886.4230 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4230 Ophthalmic knife test drum. (a) Identification. An ophthalmic knife test drum is a device intended to test the keenness of ophthalmic...

  16. 21 CFR 886.4230 - Ophthalmic knife test drum.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic knife test drum. 886.4230 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4230 Ophthalmic knife test drum. (a) Identification. An ophthalmic knife test drum is a device intended to test the keenness of ophthalmic...

  17. Quality assurance for gamma knives

    SciTech Connect

    Jones, E.D.; Banks, W.W.; Fischer, L.E.

    1995-09-01

    This report describes and summarizes the results of a quality assurance (QA) study of the Gamma Knife, a nuclear medical device used for the gamma irradiation of intracranial lesions. Focus was on the physical aspects of QA and did not address issues that are essentially medical, such as patient selection or prescription of dose. A risk-based QA assessment approach was used. Sample programs for quality control and assurance are included. The use of the Gamma Knife was found to conform to existing standards and guidelines concerning radiation safety and quality control of external beam therapies (shielding, safety reviews, radiation surveys, interlock systems, exposure monitoring, good medical physics practices, etc.) and to be compliant with NRC teletherapy regulations. There are, however, current practices for the Gamma Knife not covered by existing, formalized regulations, standards, or guidelines. These practices have been adopted by Gamma Knife users and continue to be developed with further experience. Some of these have appeared in publications or presentations and are slowly finding their way into recommendations of professional organizations.

  18. Durability of Cutting Performance of a Knife and Micro-Structural Change of a Knife Edge

    NASA Astrophysics Data System (ADS)

    Takekoshi, Kunio; Gotoh, Manabu

    The tested knife material here is mainly SUS420J2 (a kind of stainless steel). This kind of knife is very popular for daily use. From SEM observation of the initial state of the knife-edge tip after the burr removal treatment, we find either some burr and/or a micro-groove, or no burr and no micro-groove along the edge-tip. In order to abrade intentionally, the edge of a knife is repeatedly rubbed perpendicularly to the surface of a Japanese cypress woodblock using the durability-testing machine. During this rubbing process, the abrasion and/or crushing of the edge tip are observed by SEM in detail. The frictional load between the knife-edge and the woodblock is measured. Using the cutting-test machine, the cutting performance of the abraded knives is evaluated by the number of cut pieces of paper. It is discovered that the groove evolves and grows on the edge tip with abrading operation. Moreover, it is concluded that both micro-sidewalls of the groove play a role as cutting edges (i. e., the secondary edge) and this secondary edge and the groove width govern the durability of cutting performance of the knife. Especially the groove width governs it most. These conclusions are also valid for the knives made of other materials such as SUS410 and SUP10.

  19. High grade anorectal stricture complicating Crohn's disease: endoscopic treatment using insulated-tip knife

    PubMed Central

    Chon, Hyung Ku; Shin, Ik Sang; Kim, Sang Wook

    2016-01-01

    Endoscopic treatments have emerged as an alternative to surgery, in the treatment of benign colorectal stricture. Unlike endoscopic balloon dilatation, there is limited data on endoscopic electrocautery incision therapy for benign colorectal stricture, especially with regards to safety and long-term patency. We present a case of a 29-year-old female with Crohn's disease who had difficulty in defecation and passing thin stools. A pelvic magnetic resonance imaging scan, gastrograffin enema, and sigmoidoscopy showed a high-grade anorectal stricture. An endoscopic insulated-tip knife incision was successfully performed to resolve the problem. From our experience, we suggest that endoscopic insulated-tip knife treatment may be a feasible and effective modality for patients with short-segment, very rigid, fibrotic anorectal stricture. PMID:27433152

  20. High grade anorectal stricture complicating Crohn's disease: endoscopic treatment using insulated-tip knife.

    PubMed

    Chon, Hyung Ku; Shin, Ik Sang; Kim, Sang Wook; Lee, Soo Teik

    2016-07-01

    Endoscopic treatments have emerged as an alternative to surgery, in the treatment of benign colorectal stricture. Unlike endoscopic balloon dilatation, there is limited data on endoscopic electrocautery incision therapy for benign colorectal stricture, especially with regards to safety and long-term patency. We present a case of a 29-year-old female with Crohn's disease who had difficulty in defecation and passing thin stools. A pelvic magnetic resonance imaging scan, gastrograffin enema, and sigmoidoscopy showed a high-grade anorectal stricture. An endoscopic insulated-tip knife incision was successfully performed to resolve the problem. From our experience, we suggest that endoscopic insulated-tip knife treatment may be a feasible and effective modality for patients with short-segment, very rigid, fibrotic anorectal stricture. PMID:27433152

  1. The “Knife-Cut Sign” Revisited

    PubMed Central

    Cohen, Philip R.

    2015-01-01

    Background: The “knife-cut sign” is a distinctive presentation of linear erosive herpes simplex virus infection in immunocompromised patients. Purpose: To describe a man whose herpes simplex virus infection-related skin lesions demonstrated the “knife-cut sign” and to review the characteristics of reported immunosuppressed individuals with “knife-cut” cutaneous herpes simplex virus lesions. Methods: A man with multiple myeloma and post-stem cell transplant cutaneous graft-versus-host disease managed with systemic prednisone and sirolimus developed disseminated cutaneous herpes simplex virus infection with virus-associated linear ulcers of the inguinal folds and the area between his ear and scalp; the lesions at both sites had a distinctive “knife-cut” appearance. Using the PubMed database, an extensive literature search was performed on herpes simplex virus, immunocompromised patient, and “knife-cut sign”. Results: Herpes simplex virus infection-associated skin lesions that demonstrate the “knife-cut sign” present in patients who are immunosuppressed secondary to either an underlying medical condition or a systemic therapy or both. The distinctive virus-related cutaneous lesions appear as linear ulcers and fissures in intertriginous areas, such as the folds in the inguinal area, the vulva, and the abdomen; in addition, other sites include beneath the breast, within the gluteal cleft, and the area between the ear and the scalp. Not only herpes simplex virus-2, but also herpes simplex virus-1 has been observed as the causative viral serotype; indeed, herpes simplex virus-1 has been associated with genital and inframammary lesions in addition to those above the neck. Direct fluorescent antibody testing is a rapid method for confirming the clinically suspected viral infection; however, since false-negative direct fluorescent antibody testing occurred in some of the patients, it may be prudent to also perform viral cultures and possibly lesional

  2. A method for studying knife tool marks on bone.

    PubMed

    Shaw, Kai-Ping; Chung, Ju-Hui; Chung, Fang-Chun; Tseng, Bo-Yuan; Pan, Chih-Hsin; Yang, Kai-Ting; Yang, Chun-Pang

    2011-07-01

    The characteristics of knife tool marks retained on hard tissues can be used to outline the shape and angle of a knife. The purpose of this study was to describe such marks on bone tissues that had been chopped with knives. A chopping stage with a gravity accelerator and a fixed bone platform was designed to reconstruct the chopping action. A digital microscope was also used to measure the knife angle (θ) and retained V-shape tool mark angle (ψ) in a pig skull. The κ value (elasticity coefficient; θ/ψ) was derived and recorded after the knife angle (θ) and the accompanied velocity were compared with the proportional impulsive force of the knife and ψ on the bone. The constant impulsive force revealed a correlation between the V-shape tool mark angle (ψ) and the elasticity coefficient (κ). These results describe the tool marks--crucial in the medicolegal investigation--of a knife on hard tissues. PMID:21480893

  3. Knife River Indian Villages National Historic Site: Teacher's Guide.

    ERIC Educational Resources Information Center

    National Park Service (Dept. of Interior), Washington, DC. National Register of Historic Places.

    This guide provides history and social studies teachers, at all grade levels, with information and activities about the American Indians of the Northern Plains who lived in the area of the Knife River where it enters the Missouri River. Located in what is now North Dakota, this area is the Knife River Indian Villages National Historic Site. The…

  4. [LASER CONISATION VS. COLD KNIFE CONISATION FOR CIN].

    PubMed

    Karagyozov, I

    2016-01-01

    For the period of 5 years (2008-2012) at the outpatient department and the operation theater of Tokuda hospital 280 conisations were done--135 lasers and 145 cold knifes. Indications for the operation were common, with no specific choice for the aim of comparison. All patients had proven colposcopic or histologic dysplasia of the cervix. The operations were performed 2 or 3 days after menstruation. Laser conisations received local anesthesia and were not hospitalized. Cold knife conisations were done at the operation theater under regional anesthesia, they attended the hospital for 24 hours, had vaginal tapenade and urethral catheter. Indications for the operation were as follows: CIN I-14 laser and 38 cold knife conisations; CIN II-30 laser and 28 cold knife conisations; CIN III--CIS-73 laser and 74 cold knife conisations. The follow up is: 2 months after the operation-colposcopy and every 3 months afterwards--PAP smear and colposcopy for 1 year. PMID:27514128

  5. High-resolution mini gamma camera for diagnosis and radio-guided surgery in diabetic foot infection

    NASA Astrophysics Data System (ADS)

    Scopinaro, F.; Capriotti, G.; Di Santo, G.; Capotondi, C.; Micarelli, A.; Massari, R.; Trotta, C.; Soluri, A.

    2006-12-01

    The diagnosis of diabetic foot osteomyelitis is often difficult. 99mTc-WBC (White Blood Cell) scintigraphy plays a key role in the diagnosis of bone infections. Spatial resolution of Anger camera is not always able to differentiate soft tissue from bone infection. Aim of present study is to verify if HRD (High-Resolution Detector) is able to improve diagnosis and to help surgery. Patients were studied by HRD showing 25.7×25.7 mm 2 FOV, 2 mm spatial resolution and 18% energy resolution. The patients were underwent to surgery and, when necessary, bone biopsy, both guided by HRD. Four patients were positive at Anger camera without specific signs of osteomyelitis. HRS (High-Resolution Scintigraphy) showed hot spots in the same patients. In two of them the hot spot was bar-shaped and it was localized in correspondence of the small phalanx. The presence of bone infection was confirmed at surgery, which was successfully guided by HRS. 99mTc-WBC HRS was able to diagnose pedal infection and to guide the surgery of diabetic foot, opening a new way in the treatment of infected diabetic foot.

  6. Knife and impact cutting of lamb bone.

    PubMed

    King, M J

    1999-05-01

    The forces and hence fracture energies required to cut bone are presented in this paper and the merits of cutting with a high speed blade are considered. A plain knife blade was used to cut cancellous and compact lamb bone using three different methods. A microtome was used to produce a range of cut thicknesses which enabled the fracture energy to be separated into friction, surface fracture and plastic deformation energies. A tensile test machine was used to produce thicker off-cuts so that the energy required to cut through full sections of bone could be determined. A high speed rail gun was used to cut at speeds up to 130 m/s. The energy required to cut bone did not change with blade speed. However, the energies measured during the cutting varied over a wide range. In situations in which the surface of the cut bone exhibited a very uneven surface high energy was required, whereas when the resulting cut surface was planar the cutting energy was low. A light weight blade which impacts the bone at high speed will transmit a small impulse to the carcass which may be absorbed without transmitting strain to the muscle/connective tissue. This may allow the development of a high speed knife which will cut bone without excessively damaging the meat surrounding the cut. PMID:22062140

  7. Development of an air knife to remove seed coat fragments during lint cleaning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An air knife is a tool commonly used to blow off debris in a manufacturing line. The knife may also be used to break the attachment force between a lint cleaner saw and a seed coat fragment (SCF) with attached fiber, and remove them. Work continued on evaluating an auxiliary air knife mounted on t...

  8. Supernova hemorrhage: obliterative hemorrhage of brain arteriovenous malformations following γ knife radiosurgery.

    PubMed

    Alexander, Matthew D; Hetts, Steven W; Young, William L; Halbach, Van V; Dowd, Christopher F; Higashida, Randall T; English, Joey D

    2012-09-01

    Hemorrhage represents the most feared complication of cerebral arteriovenous malformations (AVMs) in both untreated patients and those treated with gamma knife radiosurgery. Radiosurgery does not immediately lead to obliteration of the malformation, which often does not occur until years following treatment. Post-obliteration hemorrhage is rare, occurring months to years after radiosurgery, and has been associated with residual or recurrent AVM despite prior apparent nidus elimination. Three cases are reported of delayed intracranial hemorrhage in patients with cerebral AVMs treated with radiosurgery in which no residual AVM was found on catheter angiography at the time of delayed post-treatment hemorrhage. That the pathophysiology of these hemorrhages involves progressive venous outflow occlusion is speculated and the possible mechanistic link to subsequent vascular rupture is discussed. PMID:21990534

  9. Robotic surgery

    MedlinePlus

    Robot-assisted surgery; Robotic-assisted laparoscopic surgery; Laparoscopic surgery with robotic assistance ... Robotic surgery is similar to laparoscopic surgery. It can be performed through smaller cuts than open surgery. ...

  10. External sclerostomy with the femtosecond laser versus a surgical knife in rabbits

    PubMed Central

    Shi, Yao; Yang, Xiao-Bo; Dai, Neng-Li; Long, Hua; Lu, Pei-Xiang; Jin, Ling; Jiang, Fa-Gang

    2012-01-01

    AIM To experimentally compare the external sclerostomy produced using a femtosecond laser with that made by a surgical knife and to evaluate the healing patterns, efficacy and technical advantages of femtosecond laser sclerostomy. METHODS In a prospective randomized, controlled, masked-observer study, 10 pigmented rabbits underwent external sclerostomy with a femtosecond laser in the right eye; 10 additional rabbits underwent sclerostomy with a surgical superblade in the right eye. Clinical characteristics, which included bleb morphology and intraocular pressure, were recorded for 1 month after surgery. Six additional rabbits underwent external femtosecond laser sclerostomy in the right eye and mechanical sclerostomy in the left eye and were killed at day 14 after surgery. Histologic staining, immunohistochemistry and scanning electron microscopy were subsequently performed to assess the morphology of the filtering fistula. The titanium-sapphire femtosecond laboratory laser was operating at a repetition rate of 1 kHz, 0.4 mJ pulse energy, a central wavelength of 800nm and a pulse duration of 50 femtoseconds. Mann-Whitney and Kaplan-Meier tests were used for statistical analysis. RESULTS Successful complete sclerostomy was achieved in each laser-treated eye which was hit only once by the laser. The laser treated time was approximately 15s-16s. In the laser-treated group (n=16), 2 eyes (12%) developed mild hyphema at the site of entry and 8 eyes (50%) showed transient edema in the corneal periphery adjacent to the laser impact zone. The differences between the groups in duration of function blebs and pressure reduction were statistically significant (P=0.025 and 0.016, respectively). The success rate of the laser-treated group was significantly higher than the knife group (P=0.005). Histologically, the subconjunctival connective tissue was loosely arranged with partially patent sclerostomy in the laser-treated eyes at postoperative day 14. This contrasted with the

  11. Effect of surface roughness on contact pressure of static seals (Sealing characteristics of knife-edge seals)

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Yoshio; Hosokawa, Kazuo; Funabashi, Koichi

    1992-09-01

    The sealing mechanism of knife-edge seals was investigated experimentally by varying the width of the flat area on the apex of the knife edge. The most suitable shape of the knife edge with the lowest compressive force for sealing was determined, and a new type of knife edge was developed.

  12. 40. Main fuses and knife switch for power to the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    40. Main fuses and knife switch for power to the bridge, located in the control house. This is one of two located at either end of the main electrical panel (photograph 41). Facing east. - Henry Ford Bridge, Spanning Cerritos Channel, Los Angeles-Long Beach Harbor, Los Angeles, Los Angeles County, CA

  13. Electromagnetic tracker accuracy in the CyberKnife suite

    NASA Astrophysics Data System (ADS)

    Wilson, Emmanuel; Slack, Rebecca; Banovac, Filip; Dieterich, Sonja; Zhang, Hui; Cleary, Kevin

    2006-03-01

    Electromagnetic trackers have found inroads into medical applications as a tool for navigation in recent years. Their susceptibility to interference from both electromagnetic and ferromagnetic sources have prompted several accuracy assessment studies in past years. To the best of our knowledge, this is the first accuracy study conducted to characterize measurement accuracy of an NDI AURORA electromagnetic tracker within a CyberKnife radiosurgery suite. CyberKnife is a frameless, stereotactic radiosurgery device used to ablate tumors within the brain, spine and in recent years, the chest and abdomen. This paper uses a data collection protocol to collect uniformly distributed data points within a subset of the AURORA measurement volume in a CyberKnife suite. The key aim of the study is to determine the extent to which large metal components of the CyberKnife stereotactic radiosurgery device and robot mount contribute to overall system performance for the AURORA electromagnetic device. A secondary goal of the work is to determine the variation in accuracy and device behavior with the presence of ionizing radiation when the LINAC is turned on.

  14. The Shoemaker's Knife--An Approach of the Polya Type.

    ERIC Educational Resources Information Center

    Libeskind, Shlomo; Lott, Johnny W.

    1984-01-01

    Archimedes' shoemaker's knife problem is interesting in its own right and also allows the demonstration of heuristic teaching ideas and a different method of doing a routine construction. The focus in the article is on the thought processes involved and questions asked when attempting proofs with the problem. (MNS)

  15. "Fist, Stick, Knife, Gun": Getting Real in Upward Bound.

    ERIC Educational Resources Information Center

    Pace, Barbara G.; Adkins, Theresa A.

    2002-01-01

    Describes how a teacher found literature for Upward Bound students. Presents Geoffrey Canada's "Fist, Stick, Knife, Gun: A Personal History of Violence in America" as a nonfiction work to provide clarity and connections that might not have been available in a fictional work, yet it had elements of literary fiction that made the text engaging. (SG)

  16. Investigation of waste glass pouring behavior over a knife edge

    SciTech Connect

    Ebadian, M.A.

    1998-01-01

    The development of vitrification technology for converting radioactive waste into a glass solid began in the early 1960s. Some problems encountered in the vitrification process are still waiting for a solution. One of them is wicking. During pouring, the glass stream flows down the wall of the pour spout until it reaches an angled cut in the wall. At this point, the stream is supposed to break cleanly away from the wall of the pour spout and fall freely into the canister. However, the glass stream is often pulled toward the wall and does not always fall into the canister, a phenomenon known as wicking. Phase 1 involves the assembly, construction, and testing of a melter capable of supplying molten glass at operational flow rates over a break-off point knife edge. Phase 2 will evaluate the effects of glass and pour spout temperatures as well as glass flow rates on the glass flow behavior over the knife edge. Phase 3 will identify the effects on wicking resulting from varying the knife edge diameter and height as well as changing the back-cut angle of the knife edge. The following tasks were completed in FY97: Design the experimental system for glass melting and pouring; Acquire and assemble the melter system; and Perform initial research work.

  17. Cosmetic Surgery

    MedlinePlus

    ... Body Looking and feeling your best Cosmetic surgery Cosmetic surgery Teens might have cosmetic surgery for a ... about my body? What are the risks of cosmetic surgery? top People who have cosmetic surgery face ...

  18. Knife mill operating factors effect on switchgrass particle size distributions

    SciTech Connect

    Bitra, V.S.P.; Womac, A.R.; Yang, Y.T.; Igathinathane, C.; Miu, P.I; Chevanan, Nehru; Sokhansanj, Shahabaddine

    2009-06-01

    Biomass particle size impacts handling, storage, conversion, and dust control systems. Switchgrass (Panicum virgatum L.) particle size distributions created by a knife mill were determined for integral classifying screen sizes from 12.7 to 50.8 mm, operating speeds from 250 to 500 rpm, and mass input rates from 2 to 11 kg/min. Particle distributions were classified with standardized sieves for forage analysis that included horizontal sieving motion with machined-aluminum sieves of thickness proportional to sieve opening dimensions. Then, a wide range of analytical descriptors were examined to mathematically represent the range of particle sizes in the distributions. Correlation coefficient of geometric mean length with knife mill screen size, feed rate, and speed were 0.872, 0.349, and 0.037, respectively. Hence, knife mill screen size largely determined particle size of switchgrass chop. Feed rate had an unexpected influence on particle size, though to a lesser degree than screen size. The Rosin Rammler function fit the chopped switchgrass size distribution data with an R2 > 0.982. Mass relative span was greater than 1, which indicated a wide distribution of particle sizes. Uniformity coefficient was more than 4.0, which indicated a large assortment of particles and also represented a well-graded particle size distribution. Knife mill chopping of switchgrass produced strongly fine skewed mesokurtic particles with 12.7 25.4 mm screens and fine skewed mesokurtic particles with 50.8 mm screen. Results of this extensive analysis of particle sizes can be applied to selection of knife mill operating parameters to produce a particular size of switchgrass chop, and will serve as a guide for relations among the various analytic descriptors of biomass particle distributions.

  19. CyberKnife Radiosurgery – Value as an Adjunct to Surgical Treatment of HCC?

    PubMed Central

    Schoenberg, Markus; Khandoga, Andrey; Stintzing, Sebastian; Trumm, Christoph; Schiergens, Tobias Simon; Angele, Martin; op den Winkel, Mark; Werner, Jens; Rentsch, Markus

    2016-01-01

    Introduction CyberKnife radiosurgery (CK) is an effective tool for the treatment of malignancies. Its greatest potential is in high-dose radiosurgery delivered to targets in organs that move with respiration, e.g., liver tumors. For hepatocellular carcinoma (HCC), however, surgical treatment (resection, transplantation) is most likely to produce long-term survival; for non-resectable tumors, therapies other than radiosurgery are typically recommended. This study evaluated the long-lasting anti-tumor effects of CK combined with surgery in patients with HCC. Materials and methods  Eighteen patients (three women, 15 men) were included in this prospective observational study. They received 21 single-fraction CK treatments (26 Gy). Patient characteristics, treatment effects, tumor response (according to the Response Evaluation Criteria In Solid Tumors (RECIST) grading) and survival were measured for a median period of 29 months. Results Local tumor control was achieved in 15 patients, with complete and partial remission observed in 10 and five patients, respectively. One patient was treated for two separate lesions in one session, and one received three treatments each separated by two-year intervals; both patients are tumor-free. Two patients showed minimal response, and in one patient local tumor viability could not be excluded by MRI. Nine patients had HCC recurrence, all distant to the treated site. Nine patients died during follow-up, including two with clear relation to tumor progress. Tumor-free survival was 79.4% after one year and 29.8% after three years, and the corresponding overall survival was 84.8% and 66%. Conclusion  This study shows the high effectiveness of single-session frameless CyberKnife radiosurgery for treatment of hepatocellular carcinoma and reconfirms previous results of fractioned radiotherapy of HCC. It also demonstrates the potential of radiosurgery to be combined with surgical concepts. PMID:27284498

  20. Trans-umbilical endoscopic cholecystectomy with a water-jet hybrid-knife: A pilot animal study

    PubMed Central

    Jiang, Sheng-Jun; Shi, Hong; Swar, Gyanendra; Wang, Hai-Xia; Liu, Xiao-Jing; Wang, Yong-Guang

    2013-01-01

    AIM: To investigate the feasibility and safety of Natural orifice trans-umbilical endoscopic cholecystectomy with a water-jet hybrid-knife in a non-survival porcine model. METHODS: Pure natural orifice transluminal endoscopic surgery (NOTES) cholecystectomy was performed on three non-survival pigs, by transumbilical approach, using a water-jet hybrid-knife. Under general anesthesia, the following steps detailed the procedure: (1) incision of the umbilicus followed by the passage of a double-channel flexible endsocope through an overtube into the peritoneal cavity; (2) establishment of pneumoperitoneum; (3) abdominal exploration; (4) endoscopic cholecystectomy: dissection of the gallbladder performed using water jet equipment, ligation of the cystic artery and duct conducted using nylon loops; and (5) necropsy with macroscopic evaluation. RESULTS: Transumbilical endoscopic cholecystectomy was successfully completed in the first and third pig, with minor bleedings. The dissection times were 137 and 42 min, respectively. The total operation times were 167 and 69 min, respectively. And the lengths of resected specimen were 6.5 and 6.1 cm, respectively. Instillation of the fluid into the gallbladder bed produced edematous, distended tissue making separation safe and easy. Reliable ligation using double nylon loops insured the safety of cutting between the loops. There were no intraoperative complications or hemodynamic instability. Uncontrolled introperative bleeding occurred in the second case, leading to the operation failure. CONCLUSION: Pure NOTES trans-umbilical cholecystectomy with a water-jet hybrid-knife appears to be feasible and safe. Further investigation of this technique with long-term follow-up in animals is needed to confirm the preliminary observation. PMID:24187461

  1. The earliest gamma unit patients.

    PubMed

    Ganz, Jeremy C

    2014-01-01

    The inventors were very excited and drove the first patient from Stockholm over 100 km for the first treatment. The treatment was a technical success. The new machine was transported to Sophiahemmet (a private Stockholm hospital) and installed. A further eight patients were treated and assessed. At the start, there was no computerized treatment planning program, but this was soon developed and named KULA after the Swedish word for a sphere, since the actual treatment unit was spherical. The term Gamma Knife was first used later by the Pittsburgh group. PMID:25376571

  2. A noninvasive eye fixation monitoring system for CyberKnife radiotherapy of choroidal and orbital tumors

    SciTech Connect

    Daftari, I. K.; Petti, P. L.; Larson, D. A.; O'Brien, J. M.; Phillips, T. L.

    2009-03-15

    A new noninvasive monitoring system for fixing the eye has been developed to treat orbital and choroidal tumors with CyberKnife-based radiotherapy. This device monitors the eye during CT/MRI scanning and during treatment. The results of this study demonstrate the feasibility of the fixation light system for CyberKnife-based treatments of orbital and choroidal tumors and supports the idea that larger choroidal melanomas and choroidal metastases could be treated with CyberKnife without implanting fiducial markers.

  3. Cataract Surgery

    MedlinePlus

    ... Uveitis Focus On Pediatric Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics ... Uveitis Focus On Pediatric Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics ...

  4. Development of knife-edge ridges on ion-bombarded surfaces

    NASA Astrophysics Data System (ADS)

    Holmes-Cerfon, Miranda; Zhou, Wei; Bertozzi, Andrea L.; Brenner, Michael P.; Aziz, Michael J.

    2012-10-01

    We demonstrate in both laboratory and numerical experiments that ion bombardment of a modestly sloped surface can create knife-edge like ridges with extremely high slopes. Small pre-fabricated pits expand under ion bombardment, and the collision of two such pits creates knife-edge ridges. Both laboratory and numerical experiments show that the pit propagation speed and the precise shape of the knife edge ridges are universal, independent of initial conditions, as has been predicted theoretically. These observations suggest a method of fabrication in which a surface is pre-patterned so that it dynamically evolves to a desired target pattern made of knife-edge ridges.

  5. A knife-edge array field emission cathode

    SciTech Connect

    Lee, B.

    1994-08-01

    many cathode applications require a new type of cathode that is able to produce short pulsed electron beams at high emission current. Gated field emitter arrays of micrometer size are recognized as candidates to meet this need and have become the research focus of vacuum microelectronics. Existing fabrication methods produce emitters that are limited either in frequency response or in current emission. One reason is that the structure of these emitters are not sufficiently optimized. In this study, the author investigated the factors that affect the performance of field emitters. An optimum emitter structure, the knife-edge field emitter array, was developed from the analysis. Large field enhancement factor, large effective emission area, and small emitter capacitance are the advantages of the structure. The author next explored various options of fabricating the knife-edge emitter structure. He proposed a unique thin film process procedure and developed the fabrication techniques to build the emitters on (110) silicon wafers. Data from the initial cathode tests showed very low onset voltages and Fowler-Nordheim type emission. Emission simulation based on the fabricated emitter structure indicated that the knife-edge emitter arrays have the potential to produce high performance in modulation frequency and current emission. Several fabrication issues that await further development are discussed and possible solutions are suggested.

  6. Direct measures of mechanical energy for knife mill size reduction

    SciTech Connect

    Bitra, V.S.P.; Womac, A.R.; Igathinathane, C.; Miu, P.I; Yang, Y.T.; Smith, D.R.; Chevanan, Nehru; Sokhansanj, Shahabaddine

    2009-08-01

    Lengthy straw/stalk of biomass may not be directly fed into grinders such as hammer mills and disc refiners. Hence, biomass needs to be preprocessed using coarse grinders like a knife mill to allow for efficient feeding in refiner mills without bridging and choking. Size reduction mechanical energy was directly measured for switchgrass (Panicum virgatum L.), wheat straw (Triticum aestivum L.), and corn stover (Zea mays L.) in an instrumented knife mill. Direct power inputs were determined for different knife mill screen openings from 12.7 to 50.8 mm, rotor speeds between 250 and 500 rpm, and mass feed rates from 1 to 11 kg/min. Overall accuracy of power measurement was calculated to be 0.003 kW. Total specific energy (kWh/Mg) was defined as size reduction energy to operate mill with biomass. Effective specific energy was defined as the energy that can be assumed to reach the biomass. The difference is parasitic or no-load energy of mill. Total specific energy for switchgrass, wheat straw, and corn stover chopping increased with knife mill speed, whereas, effective specific energy decreased marginally for switchgrass and increased for wheat straw and corn stover. Total and effective specific energy decreased with an increase in screen size for all the crops studied. Total specific energy decreased with increase in mass feed rate, but effective specific energy increased for switchgrass and wheat straw, and decreased for corn stover at increased feed rate. For knife mill screen size of 25.4 mm and optimum speed of 250 rpm, optimum feed rates were 7.6, 5.8, and 4.5 kg/min for switchgrass, wheat straw, and corn stover, respectively, and the corresponding total specific energies were 7.57, 10.53, and 8.87 kWh/Mg and effective specific energies were 1.27, 1.50, and 0.24 kWh/Mg for switchgrass, wheat straw, and corn stover, respectively. Energy utilization ratios were calculated as 16.8%, 14.3%, and 2.8% for switchgrass, wheat straw, and corn stover, respectively. These

  7. Establishing a process of irradiating small animal brain using a CyberKnife and a microCT scanner

    SciTech Connect

    Kim, Haksoo; Welford, Scott; Fabien, Jeffrey; Zheng, Yiran; Yuan, Jake; Brindle, James; Yao, Min; Lo, Simon; Wessels, Barry; Machtay, Mitchell; Sohn, Jason W.; Sloan, Andrew

    2014-02-15

    Purpose: Establish and validate a process of accurately irradiating small animals using the CyberKnife G4 System (version 8.5) with treatment plans designed to irradiate a hemisphere of a mouse brain based on microCT scanner images. Methods: These experiments consisted of four parts: (1) building a mouse phantom for intensity modulated radiotherapy (IMRT) quality assurance (QA), (2) proving usability of a microCT for treatment planning, (3) fabricating a small animal positioning system for use with the CyberKnife's image guided radiotherapy (IGRT) system, and (4)in vivo verification of targeting accuracy. A set of solid water mouse phantoms was designed and fabricated, with radiochromic films (RCF) positioned in selected planes to measure delivered doses. After down-sampling for treatment planning compatibility, a CT image set of a phantom was imported into the CyberKnife treatment planning system—MultiPlan (ver. 3.5.2). A 0.5 cm diameter sphere was contoured within the phantom to represent a hemispherical section of a mouse brain. A nude mouse was scanned in an alpha cradle using a microCT scanner (cone-beam, 157 × 149 pixels slices, 0.2 mm longitudinal slice thickness). Based on the results of our positional accuracy study, a planning treatment volume (PTV) was created. A stereotactic body mold of the mouse was “printed” using a 3D printer laying UV curable acrylic plastic. Printer instructions were based on exported contours of the mouse's skin. Positional reproducibility in the mold was checked by measuring ten CT scans. To verify accurate dose delivery in vivo, six mice were irradiated in the mold with a 4 mm target contour and a 2 mm PTV margin to 3 Gy and sacrificed within 20 min to avoid DNA repair. The brain was sliced and stained for analysis. Results: For the IMRT QA using a set of phantoms, the planned dose (6 Gy to the calculation point) was compared to the delivered dose measured via film and analyzed using Gamma analysis (3% and 3 mm). A

  8. MTF measurement of IRFPA based on double-knife edge scanning method

    NASA Astrophysics Data System (ADS)

    Ying, Cheng-ping; Wu, Bin; Wang, Heng-fei; Shi, Xue-shun; Liu, Hong-yuan

    2013-09-01

    Modulation transfer function (MTF) is one of the most important parameters of infrared focal plane array (IRFPA). A double-knife edge scanning method is proposed for MTF measurement of IRFPA. In this method, a double-knife edge was used as a target, and the IRFPA under test was positioned in the focal plane of the imaging optical system by a 3-axis translation stage. With an IRFPA data acquisition system, the image of the double-knife edge was restored. By scanning in the direction orthogonal to the double-knife edge image, edge spread function (ESF) curve of each pixel swept across the knife-edge image was obtained. MTF could be calculated from the subsequent fitting, differential and Fourier transformation procedures. With double-knife edge scanning, two ESF curves of double-knife edge were obtained simultaneously, and symmetry of the two ESF curves could be used to evaluate the verticality between photosensitive surface of IRFPA and optical axis of the double-knife edge imaging system. In addition, this method can be used to judge the existing of interference from outside such as vibration, stray light and electrical noise. A measurement facility for IRFPA's MTF based on double-knife edge scanning method was also established in this study. The facility is composed of double-knife edge imaging optical system, 3-axis translation stage and data acquisition system, et al. As the kernel of the facility, the double-knife edge imaging optical system mainly comprises two symmetrical parabolic mirrors coating with reflective material, and the magnification of the optical system is 1 with an operation wavelength range of (1˜14) μm.

  9. Two-dimensional light-distribution measurement with a 90 deg cornered knife edge

    NASA Astrophysics Data System (ADS)

    Pernick, B. J.

    1993-07-01

    An aperture-scanning technique for determining a two-dimensional light distribution is described. Results are obtained by moving a wedge-shaped, knife-edge aperture and comparing measurements from adjacent scans. The scanning procedure described herein overcomes deficiencies inherent in alternative methods that use a two-dimensional detector array or one-dimensional motion of a knife-edge aperture.

  10. Study of internal energy flows in dipole vortex beams by knife edge test

    NASA Astrophysics Data System (ADS)

    Singh, Brijesh Kumar; Bahl, Monika; Mehta, Dalip Singh; Senthilkumaran, Paramasivam

    2013-04-01

    The rotation of Poynting vector in dipole vortex beam (DVB) during propagation has been experimentally detected in a knife edge test. The dipole vortex beam is generated, when a collimated laser beam is incident on a phase mask, displayed on spatial light modulator (SLM) in reflection mode. The knife edge test reveals dipole configurations through strikingly distinct intensity intrusions in the geometrical shadow region.

  11. Removing seed coat fragments with a lint cleaner grid bar air knife

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seed coat fragments (SCF) in ginned lint cause spinning problems at the textile mill and undesirable defects in finished goods. Work continued on developing an air knife that may help remove SCF from ginned lint. The air knife is mounted on the 1st lint cleaner grid bar of a saw-type lint cleaner,...

  12. Corrections to the knife-edge based reconstruction scheme of tightly focused light beams.

    PubMed

    Huber, C; Orlov, S; Banzer, P; Leuchs, G

    2013-10-21

    The knife-edge method is an established technique for profiling light beams. It was shown, that this technique even works for tightly focused beams, if the material and geometry of the probing knife-edges are chosen carefully. Furthermore, it was also reported recently that this method fails, when the knife-edges are made from pure materials. The artifacts introduced in the reconstructed beam shape and position depend strongly on the edge and input beam parameters, because the knife-edge is excited by the incoming beam. Here we show, that the actual beam shape and spot size of tightly focused beams can still be derived from knife-edge measurements for pure edge materials and different edge thicknesses by adapting the analysis method of the experimental data taking into account the interaction of the beam with the edge. PMID:24150349

  13. Foot Surgery

    MedlinePlus

    ... About Feet » Foot Health Information Surgery When is Foot Surgery Necessary? Many foot problems do not respond ... restore the function of your foot. Types of Foot Surgery Fusions: Fusions are usually performed to treat ...

  14. Outpatient Surgery

    MedlinePlus

    Policymakers | Members | Patients | News Media Anesthesia 101 Patient Safety Stories Resources About Home » Patients » Preparing For Surgery » Types of Surgery » Outpatient Surgery Share this Page Preparing For ...

  15. Plastic Surgery

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Plastic Surgery KidsHealth > For Teens > Plastic Surgery Print A ... her forehead lightened with a laser? What Is Plastic Surgery? Just because the name includes the word " ...

  16. Robotic surgery

    MedlinePlus

    Robot-assisted surgery; Robotic-assisted laparoscopic surgery; Laparoscopic surgery with robotic assistance ... computer station and directs the movements of a robot. Small surgical tools are attached to the robot's ...

  17. Lung surgery

    MedlinePlus

    ... Pneumonectomy; Lobectomy; Lung biopsy; Thoracoscopy; Video-assisted thoracoscopic surgery; VATS ... You will have general anesthesia before surgery. You will be asleep and unable to feel pain. Two common ways to do surgery on your lungs are thoracotomy and video- ...

  18. Is transforaminal retrieval of intradiscal deeply seated broken surgical knife blade all time pars sparing? A case report

    PubMed Central

    Rahimizadeh, Abolfazl; Haddadi, Kaveh

    2015-01-01

    Background One risk accompanying with Lumbar discectomy is breaking of the surgical scalpel during discectomy. Greatest of the broken blades can be detached during the first surgery. Conversely, in few cases, surgeon’s efforts might be ineffective, causing in engaged foreign body in the disc space. Works regarding this matter is infrequent, and there are no exclusive strategies to discourse this complication. Presentation of case A 26-year-old female with L5-S1 left disc sequestration and plantar flexion disturbance, underwent a one level hemilaminectomy for lumbar disc herniation. The knife blade was broken in the disc space and could not be found despite 3 h consumed on its tried removal by her surgeon. Transforaminal path as an unconventional access strip for its removal is planned, but pars inter articularis was not saving intact and fusion process had done.The patient was discharged a day after blade removal and fusion surgery is doing well now. Conclusions The transforaminal route might be a harmless and informal substitute corridor for all intradiscal retained foreign bodies including a broken blade. Sometimes because of better exposure especially in deeply seated material, resection of pars and then fusion surgery avoid inevitable. PMID:26748209

  19. Prospective Randomized Trial on Postoperative Administration of Diet Containing Eicosapentaenoic Acid, Docosahexaenoic Acid, Gamma-linolenic Acid, and Antioxidants in Head and Neck Cancer Surgery Patients with Free-flap Reconstruction

    PubMed Central

    Tsukahara, Kiyoaki; Motohashi, Ray; Sato, Hiroki; Endo, Minoru; Ueda, Yuri; Nakamura, Kazuhiro

    2014-01-01

    OBJECTIVES The purpose of this prospective, randomized study was to evaluate the effects of a diet containing eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), gamma-linolenic acid (GLA), and antioxidants in head and neck cancer surgery patients with free-flap reconstruction. METHODS In this randomized, prospective study, 62 patients with head and neck cancers were assigned to receive a general control diet (Ensure® H; Abbott Japan, Tokyo, Japan) or the study diet (Oxepa®; Abbott Japan) containing EPA, DHA, GLA, and antioxidants (eg vitamins A, E, and C). The primary assessment item was the degree of postoperative inflammation, as assessed by measuring maximum body temperature and levels of C-reactive protein (CRP) and procalcitonin from the day of surgery to postoperative day 8. Secondary assessment items were lengths of stays in the intensive care unit (ICU) and hospital. RESULTS The control diet group (n = 32) and study diet group (n = 30) showed no significant difference in energy administered through diet. No significant differences in the parameters of the primary assessment item were noted. Length of stay in the ICU was significantly shorter for the control diet group than for the study diet group (P = 0.011). No significant difference in duration of hospitalization was seen between groups. CONCLUSION No usefulness of a diet containing EPA, DHA, GLA, and antioxidants was demonstrated. PMID:25368541

  20. Endoscopic treatment for pancreatic diseases: Needle-knife-guided cannulation via the minor papilla

    PubMed Central

    Wang, Wei; Gong, Biao; Jiang, Wei-Song; Liu, Lei; Bielike, Kouken; Xv, Bin; Wu, Yun-Lin

    2015-01-01

    AIM: To determine the efficacy and safety of meticulous cannulation by needle-knife. METHODS: Three needle-knife procedures were used to facilitate cannulation in cases when standard cannulation techniques failed. A total of 104 cannulations via the minor papilla attempted in 74 patients at our center between January 2008 and June 2014 were retrospectively reviewed. RESULTS: Standard methods were successful in 79 cannulations. Of the 25 cannulations that could not be performed by standard methods, 19 were performed by needle-knife, while 17 (89.5%) were successful. Needle-knife use improved the success rate of cannulation [76.0%, 79/104 vs 92.3%, (79 + 17)/104; P = 0.001]. When the 6 cases not appropriate for needle-knife cannulation were excluded, the success rate was improved further (80.6%, 79/98 vs 98.0%, 96/98; P = 0.000). There were no significant differences in the rates of post-endoscopic retrograde cholangiopancreatography adverse events between the group using standard methods alone and the group using needle-knife after failure of standard methods (4.7% vs 10.5%, P = 0.301). CONCLUSION: The needle-knife procedure may be an alternative method for improving the success rate of cannulation via the minor papilla, particularly when standard cannulation has failed. PMID:26019460

  1. Structural shielding design for a gamma ray stereotactic body radiotherapy system.

    PubMed

    Xie, Xiangdong; Yang, Guoshan; Zhou, Hongmei; Qu, Decheng

    2006-09-01

    An OUR-QGD gamma ray stereotactic body radiotherapy system (body knife), made in China, is described. According to its structure and the principle of gamma radiation revolved on a focus, the energy distribution of scattered radiation in its treatment room is calculated. The structural shielding of the wall, roof, and door for a certain treatment room is calculated according to the local radiation protection law. PMID:16926472

  2. Development of knife-edge field emission cathodes on (110) silicon wafers

    NASA Astrophysics Data System (ADS)

    Lee, Bo; Barasch, E. F.; Mazumdar, T.; McIntyre, P. M.; Pang, Y.; Trost, H.-J.

    1993-04-01

    Knife-edge field emission cathodes have been fabricated on (110) silicon wafers. The emitter structure consists of an array of razor shaped silicon knife edges standing up on silicon substrates. The radii of the sharp edges seen with SEM are less than 250 Å; the height of the knife edges is 5 to 8 μm; and the gate-emitter spacing is ˜0.1 μm. Because of the very small gate-emitter spacing and the large height/width ratio of the emitter, the structure resembles an optimized emitter geometry concluded from our study. The fabrication process and results are presented.

  3. The next evolution in radioguided surgery: breast cancer related sentinel node localization using a freehandSPECT-mobile gamma camera combination.

    PubMed

    Engelen, Thijs; Winkel, Beatrice Mf; Rietbergen, Daphne Dd; KleinJan, Gijs H; Vidal-Sicart, Sergi; Olmos, Renato A Valdés; van den Berg, Nynke S; van Leeuwen, Fijs Wb

    2015-01-01

    Accurate pre- and intraoperative identification of the sentinel node (SN) forms the basis of the SN biopsy procedure. Gamma tracing technologies such as a gamma probe (GP), a 2D mobile gamma camera (MGC) or 3D freehandSPECT (FHS) can be used to provide the surgeon with radioguidance to the SN(s). We reasoned that integrated use of these technologies results in the generation of a "hybrid" modality that combines the best that the individual radioguidance technologies have to offer. The sensitivity and resolvability of both 2D-MGC and 3D-FHS-MGC were studied in a phantom setup (at various source-detector depths and using varying injection site-to-SN distances), and in ten breast cancer patients scheduled for SN biopsy. Acquired 3D-FHS-MGC images were overlaid with the position of the phantom/patient. This augmented-reality overview image was then used for navigation to the hotspot/SN in virtual-reality using the GP. Obtained results were compared to conventional gamma camera lymphoscintigrams. Resolution of 3D-FHS-MGC allowed identification of the SNs at a minimum injection site (100 MBq)-to-node (1 MBq; 1%) distance of 20 mm, up to a source-detector depth of 36 mm in 2D-MGC and up to 24 mm in 3D-FHS-MGC. A clinically relevant dose of approximately 1 MBq was clearly detectable up to a depth of 60 mm in 2D-MGC and 48 mm in 3D-FHS-MGC. In all ten patients at least one SN was visualized on the lymphoscintigrams with a total of 12 SNs visualized. 3D-FHS-MGC identified 11 of 12 SNs and allowed navigation to all these visualized SNs; in one patient with two axillary SNs located closely to each other (11 mm), 3D-FHS-MGC was not able to distinguish the two SNs. In conclusion, high sensitivity detection of SNs at an injection site-to-node distance of 20 mm-and-up was possible using 3D-FHS-MGC. In patients, 3D-FHS-MGC showed highly reproducible images as compared to the conventional lymphoscintigrams. PMID:26069857

  4. Is It Useful and Safe to Maintain the Sitting Position During Only One Minute before Position Change to the Jack-knife Position?

    PubMed Central

    Park, Soo Young; Park, Jong Cook

    2010-01-01

    Background Conventional spinal saddle block is performed with the patient in a sitting position, keeping the patient sitting for between 3 to 10 min after injection of a drug. This amount of time, however, is long enough to cause prolonged postoperative urinary retention. The trend in this block is to lower the dose of local anesthetics, providing a selective segmental block; however, an optimal dose and method are needed for adequate anesthesia in variable situations. Therefore, in this study, we evaluated the question of whether only 1 min of sitting after drug injection would be sufficient and safe for minor anorectal surgery. Methods Two hundred and sixteen patients undergoing minor anorectal surgery under spinal anesthesia remained sitting for 1 min after completion of subarachnoid administration of 1 ml of a 0.5% hyperbaric bupivacaine solution (5 mg). They were then placed in the jack-knife position. After surgery, analgesia levels were assessed using loss of cold sensation in the supine position. The next day, urination and 11-point numeric rating scale (NRS) for postoperative pain were assessed. Results None of the patients required additional analgesics during surgical manipulation. Postoperative sensory levels were T10 [T8-T12] in patients, and no significant differences were observed between sex (P = 0.857), height (P = 0.065), obesity (P = 0.873), or age (P = 0.138). Urinary retention developed in only 7 patients (3.2%). In this group, NRS was 5.0 ± 2.4 (P = 0.014). Conclusions The one-minute sitting position for spinal saddle block before the jack-knife position is a safe method for use with minor anorectal surgery and can reduce development of postoperative urinary retention. PMID:20830265

  5. INVESTIGATION OF WASTE GLASS POURING PROCESS OVER A KNIFE EDGE

    SciTech Connect

    M.A. Ebadian, Ph.D.

    1999-01-01

    Vitrification is the process of capturing radioactive waste in glass. The Savannah River Site's (SRS) Defense Waste Processing Facility (DWPF) is one of the facilities using the vitrification technology to treat and immobilize radioactive waste. The objective of the project is to investigate the pouring behavior of molten glass over a pour spout knife edge. Experiments are run using simulant glass containing the same chemical formulation as the radioactive sludge glass, but without radioactive contaminants. The purpose of these tests is to obtain actual glass data that, when combined with previous cold data from other fluids, will provide an overall understanding of the physics of liquids flowing over a pour spout and knife edge, A specific objective is to verify computational fluid dynamics (CFD) models with a range of liquid data with particular emphasis on glass so as to provide confidence in use of these CFD models for designing a new improved pour spout for the DWPF melter. The work to be performed at FIU-HCET includes assembling the melting and pouring system that mimics the DWPF melter and determining the key parameters that may influence wicking. Information from the FIU-HCET melter tests will lead to better operating guidelines for the DWPF melter so as to avoid wicking. During FY98, a bench-scale melter complete with pour spout and a knife edge was designed and assembled at FIU-HCET. Initially, the system was tested with glycerine. Subsequently, glass provided by SRS was used for experimentation. Flow visualization tests were performed with the melter in FY98 to investigate the pouring behavior of molten glass over a pour spout model simulating a DWPF pour spout of the original design. Simulant glass containing the same chemical formulation as sludge glass but without radioactive contaminants was used in the tests. All the tasks and milestones mentioned in the PTP for the project were accomplished. The project completed its second year, and this document

  6. Clinical outcomes of CyberKnife stereotactic body radiotherapy for peripheral stage I non-small cell lung cancer.

    PubMed

    Shen, Ze-Tian; Wu, Xin-Hu; Li, Bing; Zhu, Xi-Xu

    2015-03-01

    The aim of this study was to evaluate the clinical outcome of CyberKnife stereotactic body radiotherapy (SBRT) for patients with stage I non-small cell lung cancer (NSCLC). Fifty patients with peripheral stage I NSCLC who refused surgery or were medically inoperable were treated with 48-60 Gy (median dose: 57 Gy) in three divided doses. Histopathology was available in 86% of patients. Thirty patients had a T1 tumor, and 20 patients had T2 tumors. More than 95% of the target volume was covered by the 72% isodose surface. Fiducials were implanted in or near the tumors in all patients to track tumor movement and breathing patterns. The median follow-up time was 35 months (3-45 months). Based on computed tomography scans, 40 patients achieved complete remission, six patients achieved partial remission, two patients exhibited stable disease, and two patients had progressive disease. The local control rate (CR + PR) was 92%, and the 2-year disease control rate (CR + PR + SD) was 96%. Overall survival for the whole group was 86% at 1 year and 74% at 2 years. Grade III toxicity occurred in two patients (4%) after marker placement. Treatment-related late grade III toxicity occurred in five patients (10%). Toxicities greater than grade III were not observed. CyberKnife SBRT achieves a high rate of local control and long-term curative effect with acceptable toxicity for patients with inoperable stage I NSCLC. However, long-term follow-up is necessary to evaluate survival and late toxicity. PMID:25638468

  7. Radioguided Adrenal Surgery

    PubMed Central

    Deus, Javier; Millera, Alfonso; Andrés, Alejandro; Prats, Enrique; Gil, Ismael; Suarez, Manuel; Salcini, José L.; Lahoz, Manuel

    2015-01-01

    Abstract The laparoscopic adrenalectomy is considered as the procedure of choice for the treatment of adrenal hyperplasia and tumor lesions. However, some special situations may limit the use of this method due to the difficulty to locate the gland and perform the lesion excision. We analyze 2 patients of a left adrenal tumor, explaining how they have overcome the difficulties in both situations. The first case was a patient with a history of intra-abdominal surgery and the other patient suffered from severe obesity. We performed with the use of the gamma probe, and the 2 cases, was of great help to access and glandular localization. The help of gamma probe test was achieved in the surgical bed, that removal was complete. The use of the portable gamma probe facilitated the access to the left adrenal gland as well as conducting the glandular excision without delay, despite the difficulties due to the intra abdominal surgery caused by the previous surgery, and in the case of severe obesity. PMID:26426608

  8. SU-E-J-64: Feasibility Study of Surgical Clips for Fiducial Tracking in CyberKnife System

    SciTech Connect

    Lee, H; Yoon, J; Lee, E; Cho, S; Park, K; Choi, W; Baek, J; Keum, K; Koom, W

    2015-06-15

    Purpose: To investigate the ability of CyberKnife to track surgical clips used as fiducial markers. Methods: The Octavius 1000SRS detector and solid water (RW3) slab phantom were used with motion platform to evaluate the study. The RW3 slab phantom was set up to measure the dose distribution from coronal plane. It consists of 9 plates and the thickness of each plate is 10mm. Among them, one plate was attached with 3 surgical clips, which are orthogonally positioned on outer region of array. The length of attached clip was represented as 1cm on planning CT. The clip plate was placed on the 1000SRS detector and 3 slabs were stacked up on the plate to build the measuring depth. Below the detector, 5 slabs were set. The two-axis motion platform was programmed with 1D sinusoidal movement (20mm peak-to-peak, 3s period) toward superior/inferior and left/right directions to simulate target motion. During delivery, two clips were extracted by two X-ray imagers, which led to translational error correction only. Synchrony was also used for dynamic tracking. After the irradiation, the measured dose distribution of coronal plane was compared with the planar dose distribution calculated by the CyberKnife treatment planning system (Multiplan) for cross verification. The results were assessed by comparing the absolute Gamma (γ) index. Results: The dose distributions measured by the 1000SRS detector were in good agreements with those calculated by Multiplan. In the dosimetric comparison using γ-function criteria based on the distance-to-agreement of 3mm and the local dose difference of 3%, the passing rate with γ- parameter ≤1 was 91% in coronal plane. Conclusion: The surgical clips can be considered as new fiducials for robotic radiosurgery delivery by considering the target margin with less than 5mm.

  9. In-line digital holography with double knife edge

    NASA Astrophysics Data System (ADS)

    Ramirez, Claudio; Iemmi, Claudio; Campos, Juan

    2015-06-01

    We study and test a new technique for in-line digital holography which avoids the formation of the conjugate images. Inline digital holography is based in a common path configuration. In this case, the hologram is produced by the interference between the reference wave front and the diffracted wave front by an almost transparent object. Twin images are obtained with obscured rings that difficult the determination of the best focusing plane. To avoid the conjugated image, the information of the magnitude and phase of the wave front are needed. In a recent work a new in-line digital holography technique was proposed. In this method the object is illuminated with a collimated wave front. A plane, close to the particles distribution is imaged onto a CCD by means of a convergent lens and at the same time, a knife edge is placed in the focal plane of the lens in order to block half of spatial frequency spectrum. In this way, by means of a numerical processing performed on the Fourier plane, it is possible to eliminate one of the components (real or conjugate) of the reconstructed images nevertheless it is observed a tiny deformation of the resulting hologram image. To compensate this effect, we propose a new configuration in which we implement the knife edge technique on both parts of the spectrum at the same time. Finally in the computer, we process the holograms to build one complete without deformation. This hologram is used to recover the wave front at different planes without the influence of the conjugate image.

  10. A novel technique of anesthesia induction in supine position with impaled knife in the back

    PubMed Central

    Kumar, Ajay; Saha, Kamales Kumar; Jagiasi, Bharat; Saha, Kakalee K

    2015-01-01

    Current technique of airway management for impaled knife in the back includes putting the patient in lateral position and intubation. We present here a novel technique of anesthesia induction (intubation and central line insertion) in a patient with impaled knife in the back which is simple and easily reproducible. This technique can be used for single lung ventilation using double lumen tube or bronchial blocker also if desired. PMID:25849698