Sample records for gamma knife dose

  1. 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

  2. SU-E-T-453: Optimization of Dose Gradient for Gamma Knife Radiosurgery.

    PubMed

    Sheth, N; Chen, Y; Yang, J

    2012-06-01

    The goals of stereotactic radiosurgery (SRS) are the ablation of target tissue and sparing of critical normal tissue. We develop tools to aid in the selection of collimation and prescription (Rx) isodose line to optimize the dose gradient for single isocenter intracranial stereotactic radiosurgery (SRS) with GammaKnife 4C utilizing the updated physics data in GammaPlan v10.1. Single isocenter intracranial SRS plans were created to treat the center of a solid water anthropomorphism head phantom for each GammaKnife collimator (4 mm, 8 mm, 14 mm, and 18 mm). The dose gradient, defined as the difference of effective radii of spheres equal to half and full Rx volumes, and Rx treatment volume was analyzed for isodoses from 99% to 20% of Rx. The dosimetric data on Rx volume and dose gradient vs. Rx isodose for each collimator was compiled into an easy to read nomogram as well as plotted graphically. The 4, 8, 14, and 18 mm collimators have the sharpest dose gradient at the 64%, 70%, 76%, and 77% Rx isodose lines, respectively. This corresponds to treating 4.77 mm, 8.86 mm, 14.78 mm, and 18.77 mm diameter targets with dose gradients radii of 1.06 mm, 1.63 mm, 2.54 mm, and 3.17 mm, respectively. We analyzed the dosimetric data for the most recent version of GammaPlan treatment planning software to develop tools that when applied clinically will aid in the selection of a collimator and Rx isodose line for optimal dose gradient and target coverage for single isocenter intracranial SRS with GammaKnife 4C. © 2012 American Association of Physicists in Medicine.

  3. Shot sequencing based on biological equivalent dose considerations for multiple isocenter Gamma Knife radiosurgery.

    PubMed

    Ma, Lijun; Lee, Letitia; Barani, Igor; Hwang, Andrew; Fogh, Shannon; Nakamura, Jean; McDermott, Michael; Sneed, Penny; Larson, David A; Sahgal, Arjun

    2011-11-21

    Rapid delivery of multiple shots or isocenters is one of the hallmarks of Gamma Knife radiosurgery. In this study, we investigated whether the temporal order of shots delivered with Gamma Knife Perfexion would significantly influence the biological equivalent dose for complex multi-isocenter treatments. Twenty single-target cases were selected for analysis. For each case, 3D dose matrices of individual shots were extracted and single-fraction equivalent uniform dose (sEUD) values were determined for all possible shot delivery sequences, corresponding to different patterns of temporal dose delivery within the target. We found significant variations in the sEUD values among these sequences exceeding 15% for certain cases. However, the sequences for the actual treatment delivery were found to agree (<3%) and to correlate (R² = 0.98) excellently with the sequences yielding the maximum sEUD values for all studied cases. This result is applicable for both fast and slow growing tumors with α/β values of 2 to 20 according to the linear-quadratic model. In conclusion, despite large potential variations in different shot sequences for multi-isocenter Gamma Knife treatments, current clinical delivery sequences exhibited consistent biological target dosing that approached that maximally achievable for all studied cases.

  4. Shot sequencing based on biological equivalent dose considerations for multiple isocenter Gamma Knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Ma, Lijun; Lee, Letitia; Barani, Igor; Hwang, Andrew; Fogh, Shannon; Nakamura, Jean; McDermott, Michael; Sneed, Penny; Larson, David A.; Sahgal, Arjun

    2011-11-01

    Rapid delivery of multiple shots or isocenters is one of the hallmarks of Gamma Knife radiosurgery. In this study, we investigated whether the temporal order of shots delivered with Gamma Knife Perfexion would significantly influence the biological equivalent dose for complex multi-isocenter treatments. Twenty single-target cases were selected for analysis. For each case, 3D dose matrices of individual shots were extracted and single-fraction equivalent uniform dose (sEUD) values were determined for all possible shot delivery sequences, corresponding to different patterns of temporal dose delivery within the target. We found significant variations in the sEUD values among these sequences exceeding 15% for certain cases. However, the sequences for the actual treatment delivery were found to agree (<3%) and to correlate (R2 = 0.98) excellently with the sequences yielding the maximum sEUD values for all studied cases. This result is applicable for both fast and slow growing tumors with α/β values of 2 to 20 according to the linear-quadratic model. In conclusion, despite large potential variations in different shot sequences for multi-isocenter Gamma Knife treatments, current clinical delivery sequences exhibited consistent biological target dosing that approached that maximally achievable for all studied cases.

  5. Repeat Gamma-Knife Radiosurgery for Refractory or Recurrent Trigeminal Neuralgia with Consideration About the Optimal Second Dose.

    PubMed

    Park, Seong-Cheol; Kwon, Do Hoon; Lee, Do Hee; Lee, Jung Kyo

    2016-02-01

    To investigate adequate radiation doses for repeat Gamma Knife radiosurgery (GKS) for trigeminal neuralgia in our series and meta-analysis. Fourteen patients treated by ipsilateral repeat GKS for trigeminal neuralgia were included. Median age of patients was 65 years (range, 28-78), the median target dose, 140-180). Patients were followed a median of 10.8 months (range, 1-151) after the second gamma-knife surgery. Brainstem dose analysis and vote-counting meta-analysis of 19 studies were performed. After the second gamma-knife radiosurgeries, pain was relieved effectively in 12 patients (86%; Barrow Neurological Institute Pain Intensity Score I-III). Post-gamma-knife radiosurgery trigeminal nerve deficits were mild in 5 patients. No serious anesthesia dolorosa was occurred. The second GKS radiation dose ≤ 60 Gy was significantly associated with worse pain control outcome (P = 0.018 in our series, permutation analysis of variance, and P = 0.009 in the meta-analysis, 2-tailed Fisher's exact test). Cumulative dose ≤ 140-150 Gy was significantly associated with poor pain control outcome (P = 0.033 in our series and P = 0.013 in the meta-analysis, 2-tailed Fisher's exact test). A cumulative brainstem edge dose >12 Gy tended to be associated with trigeminal nerve deficit (P = 0.077). Our study suggests that the second GKS dose is a potentially important factor. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. 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

    2016-07-08

    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

  7. Two‐year experience with the commercial Gamma Knife Check software

    PubMed Central

    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

  8. Dosimetric effects of Onyx embolization on Gamma Knife arteriovenous malformation dose distributions.

    PubMed

    Schlesinger, David J; Nordström, Håkan; Lundin, Anders; Xu, Zhiyuan; Sheehan, Jason P

    2016-12-01

    OBJECTIVE Patients with arteriovenous malformations (AVMs) treated with Gamma Knife radiosurgery (GKRS) subsequent to embolization suffer from elevated local failure rates and differences in adverse radiation effects. Onyx is a common embolic material for AVMs. Onyx is formulated with tantalum, a high atomic number (Z = 73) element that has been investigated as a source of dosimetric uncertainty contributing to the less favorable clinical results. However, prior studies have not modeled the complicated anatomical and beam geometries characteristic of GKRS. This study investigated the magnitude of dose perturbation that can occur due to Onyx embolization using clinically realistic anatomical and Gamma Knife beam models. METHODS Leksell GammaPlan (LGP) was used to segment the AVM nidus and areas of Onyx from postcontrast stereotactic MRI for 7 patients treated with GKRS postembolization. The resulting contours, skull surface, and clinically selected dose distributions were exported from LGP in DICOM-RT (Digital Imaging and Communications in Medicine-radiotherapy) format. Isocenter locations and dwell times were recorded from the LGP database. Contours were converted into 3D mesh representations using commercial and in-house mesh-editing software. The resulting data were imported into a Monte Carlo (MC) dose calculation engine (Pegasos, Elekta Instruments AB) with a beam geometry for the Gamma Knife Perfexion. The MC-predicted dose distributions were calculated with Onyx assigned manufacturer-reported physical constants (MC-Onyx), and then compared with corresponding distributions in which Onyx was reassigned constants for water (MC-water). Differences in dose metrics were determined, including minimum, maximum, and mean dose to the AVM nidus; selectivity index; and target coverage. Combined differences in dose magnitude and distance to agreement were calculated as 3D Gamma analysis passing rates using tolerance criteria of 0.5%/0.5 mm, 1.0%/1.0 mm, and 3.0%/3.0 mm

  9. Gamma Knife

    MedlinePlus

    ... equipment? How is safety ensured? What is this equipment used for? The Gamma Knife® and its associated ... in size. top of page How does the equipment work? The Gamma Knife® utilizes a technique called ...

  10. MO-F-CAMPUS-T-03: Continuous Dose Delivery with Gamma Knife Perfexion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ghobadi,; Li, W; Chung, C

    2015-06-15

    Purpose: We propose continuous dose delivery techniques for stereotactic treatments delivered by Gamma Knife Perfexion using inverse treatment planning system that can be applied to various tumour sites in the brain. We test the accuracy of the plans on Perfexion’s planning system (GammaPlan) to ensure the obtained plans are viable. This approach introduces continuous dose delivery for Perefxion, as opposed to the currently employed step-and-shoot approaches, for different tumour sites. Additionally, this is the first realization of automated inverse planning on GammaPlan. Methods: The inverse planning approach is divided into two steps of identifying a quality path inside the target,more » and finding the best collimator composition for the path. To find a path, we select strategic regions inside the target volume and find a path that visits each region exactly once. This path is then passed to a mathematical model which finds the best combination of collimators and their durations. The mathematical model minimizes the dose spillage to the surrounding tissues while ensuring the prescribed dose is delivered to the target(s). Organs-at-risk and their corresponding allowable doses can also be added to the model to protect adjacent organs. Results: We test this approach on various tumour sizes and sites. The quality of the obtained treatment plans are comparable or better than forward plans and inverse plans that use step- and-shoot technique. The conformity indices in the obtained continuous dose delivery plans are similar to those of forward plans while the beam-on time is improved on average (see Table 1 in supporting document). Conclusion: We employ inverse planning for continuous dose delivery in Perfexion for brain tumours. The quality of the obtained plans is similar to forward and inverse plans that use conventional step-and-shoot technique. We tested the inverse plans on GammaPlan to verify clinical relevance. This research was partially supported by

  11. Embolization with Gamma Knife Radiosurgery of Giant Intracranial Arteriovenous Malformations.

    PubMed

    Chun, Dong Hyun; Kim, Moo Seong; Kim, Sung Tae; Paeng, Sung Hwa; Jeong, Hae Woong; Lee, Won Hee

    2016-01-01

    Giant arteriovenous malformations (i.e., those greater than 6 cm maximum diameter or volume > 33 cc) are difficult to treat and often carry higher treatment morbidity and mortality rates. In our study, we reviewed the angiographic results and clinical outcomes for 11 patients with giant arteriovenous malformations who were treated between 1994 and 2012. The patients selected included 9 males (82%) and 2 females (18%). Their presenting symptoms were hemorrhage (n=2; 18%), seizure (n=7; 64%), and headache (n=2; 12%). Nine patients were Spetzler-Martin Grade III, 2 were Spetzler-Martin Grade IV. The mean arteriovenous malformation volume was 41 cc (33-52 cc). The mean age of the patients was 45.1 years (24-57 years) and the mean radiation dose delivered to the margin of the nidus was 14.2 Gy. Ten patients received pre-Gamma Knife radiosurgery embolization and Gamma Knife radiosurgery, 1 patient received pre-Gamma Knife radiosurgery embolization and Gamma Knife radiosurgery twice and the interval between Gamma Knife radiosurgeries was 3 months. The complete obliteration rate following Gamma Knife radiosurgery was 36%, subtotal obliteration ( > 70% decreased size of nidus) was 36%, and partial obliteration was 28%. One patient experienced a small hemorrhage after embolization. Combined embolization and Gamma Knife radiosurgery showed successful obliteration of the arteriovenous malformation nidus. The use of embolization to initially reduce nidus size followed by Gamma Knife radiosurgery improves the treatment results. Repeated Gamma Knife radiosurgery should be a treatment option when there is a small nidus remnant.

  12. Dose verification to cochlea during gamma knife radiosurgery of acoustic schwannoma using MOSFET dosimeter.

    PubMed

    Sharma, Sunil D; Kumar, Rajesh; Akhilesh, Philomina; Pendse, Anil M; Deshpande, Sudesh; Misra, Basant K

    2012-01-01

    Dose verification to cochlea using metal oxide semiconductor field effect transistor (MOSFET) dosimeter using a specially designed multi slice head and neck phantom during the treatment of acoustic schwannoma by Gamma Knife radiosurgery unit. A multi slice polystyrene head phantom was designed and fabricated for measurement of dose to cochlea during the treatment of the acoustic schwannoma. The phantom has provision to position the MOSFET dosimeters at the desired location precisely. MOSFET dosimeters of 0.2 mm x 0.2 mm x 0.5 μm were used to measure the dose to the cochlea. CT scans of the phantom with MOSFETs in situ were taken along with Leksell frame. The treatment plans of five patients treated earlier for acoustic schwannoma were transferred to the phantom. Dose and coordinates of maximum dose point inside the cochlea were derived. The phantom along with the MOSFET dosimeters was irradiated to deliver the planned treatment and dose received by cochlea were measured. The treatment planning system (TPS) estimated and measured dose to the cochlea were in the range of 7.4 - 8.4 Gy and 7.1 - 8 Gy, respectively. The maximum variation between TPS calculated and measured dose to cochlea was 5%. The measured dose values were found in good agreement with the dose values calculated using the TPS. The MOSFET dosimeter can be a suitable choice for routine dose verification in the Gamma Knife radiosurgery.

  13. Comparison of full width at half maximum and penumbra of different Gamma Knife models.

    PubMed

    Asgari, Sepideh; Banaee, Nooshin; Nedaie, Hassan Ali

    2018-01-01

    As a radiosurgical tool, Gamma Knife has the best and widespread name recognition. Gamma Knife is a noninvasive intracranial technique invented and developed by Swedish neurosurgeon Lars Leksell. The first commercial Leksell Gamma Knife entered the therapeutic armamentarium at the University of Pittsburgh in the United States on August 1987. Since that time, different generation of Gamma Knife developed. In this study, the technical points and dosimetric parameters including full width at half maximum and penumbra on different generation of Gamma Knife will be reviewed and compared. The results of this review study show that the rotating gamma system provides a better dose conformity.

  14. 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

  15. Current gamma knife treatment for ophthalmic branch of primary trigeminal neuralgia

    PubMed Central

    Shan, Guo-Yong; Liang, Hao-Fang; Zhang, Jian-Hua

    2011-01-01

    AIM To probe into problems existing in gamma knife treatment of ophthalmic branch of primary trigeminal neuralgia (TN), and propose a safe and effective solution to the problem. METHODS Through sorting the literature reporting gamma knife treatment of refractory TN in recent years, this article analyzed the advantages and problems of gamma knife treatment of primary TN, and proposed reasonable assessment for existing problems and the possible solution. RESULTS Gamma knife treatment of TN has drawn increasing attention of clinicians due to its unique non-invasion, safety and effectiveness, but there are three related issues to be considered. The first one is the uncertainty of the optimal dose (70-90GY); the second one is the difference in radiotherapy target selection (using a single isocenter or two isocenters); and the third one is the big difference of recurrent pains (specific treatment methods need to be summarized and improved). CONCLUSION For patients with refractory TN, gamma knife treatment can be selected when the medical treatment fails or drug side effects emerge. The analysis of a large number of TN patients receiving gamma knife treatment has shown that this is a safe and effective treatment method. PMID:22553625

  16. SU-F-T-370: A Fast Monte Carlo Dose Engine for Gamma Knife

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Song, T; Zhou, L; Li, Y

    2016-06-15

    Purpose: To develop a fast Monte Carlo dose calculation algorithm for Gamma Knife. Methods: To make the simulation more efficient, we implemented the track repeating technique on GPU. We first use EGSnrc to pre-calculate the photon and secondary electron tracks in water from two mono-energy photons of 60Co. The total photon mean free paths for different materials and energies are obtained from NIST. During simulation, each entire photon track was first loaded to shared memory for each block, the incident original photon was then splitted to Nthread sub-photons, each thread transport one sub-photon, the Russian roulette technique was applied formore » scattered and bremsstrahlung photons. The resultant electrons from photon interactions are simulated by repeating the recorded electron tracks. The electron step length is stretched/shrunk proportionally based on the local density and stopping power ratios of the local material. Energy deposition in a voxel is proportional to the fraction of the equivalent step length in that voxel. To evaluate its accuracy, dose deposition in a 300mm*300mm*300mm water phantom is calculated, and compared to EGSnrc results. Results: Both PDD and OAR showed great agreements (within 0.5%) between our dose engine result and the EGSnrc result. It only takes less than 1 min for every simulation, being reduced up to ∼40 times compared to EGSnrc simulations. Conclusion: We have successfully developed a fast Monte Carlo dose engine for Gamma Knife.« less

  17. Gamma knife radiosurgery for cerebellopontine angle epidermoid tumors.

    PubMed

    El-Shehaby, Amr M N; Reda, Wael A; Abdel Karim, Khaled M; Emad Eldin, Reem M; Nabeel, Ahmed M

    2017-01-01

    Intracranial epidermoid tumors are commonly found in the cerebellopontine angle where they usually present with either trigeminal neuralgia or hemifacial spasm. Radiosurgery for these tumors has rarely been reported. The purpose of this study is to assess the safety and clinical outcome of the treatment of cerebellopontine epidermoid tumors with gamma knife radiosurgery. This is a retrospective study involving 12 patients harboring cerebellopontine angle epidermoid tumors who underwent 15 sessions of gamma knife radiosurgery. Trigeminal pain was present in 8 patients and hemifacial spasm in 3 patients. All cases with trigeminal pain were receiving medication and still uncontrolled. One patient with hemifacial spasm was medically controlled before gamma knife and the other two were not. Two patients had undergone surgical resection prior to gamma knife treatment. The median prescription dose was 11 Gy (10-11 Gy). The tumor volumes ranged from 3.7 to 23.9 cc (median 10.5 cc). The median radiological follow up was 2 years (1-5 years). All tumors were controlled and one tumor shrank. The median clinical follow-up was 5 years. The trigeminal pain improved or disappeared in 5 patients, and of these, 4 cases stopped their medication and one decreased it. The hemifacial spasm resolved in 2 patients who were able to stop their medication. Facial palsy developed in 1 patient and improved with conservative treatment. Transient diplopia was also reported in 2 cases. Gamma knife radiosurgery provides good clinical control for cerebellopontine angle epidermoid tumors.

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

    PubMed

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

    2005-05-07

    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.

  19. Gamma knife radiosurgery for cerebellopontine angle epidermoid tumors

    PubMed Central

    El-Shehaby, Amr M. N.; Reda, Wael A.; Abdel Karim, Khaled M.; Emad Eldin, Reem M.; Nabeel, Ahmed M.

    2017-01-01

    Background: Intracranial epidermoid tumors are commonly found in the cerebellopontine angle where they usually present with either trigeminal neuralgia or hemifacial spasm. Radiosurgery for these tumors has rarely been reported. The purpose of this study is to assess the safety and clinical outcome of the treatment of cerebellopontine epidermoid tumors with gamma knife radiosurgery. Methods: This is a retrospective study involving 12 patients harboring cerebellopontine angle epidermoid tumors who underwent 15 sessions of gamma knife radiosurgery. Trigeminal pain was present in 8 patients and hemifacial spasm in 3 patients. All cases with trigeminal pain were receiving medication and still uncontrolled. One patient with hemifacial spasm was medically controlled before gamma knife and the other two were not. Two patients had undergone surgical resection prior to gamma knife treatment. The median prescription dose was 11 Gy (10–11 Gy). The tumor volumes ranged from 3.7 to 23.9 cc (median 10.5 cc). Results: The median radiological follow up was 2 years (1–5 years). All tumors were controlled and one tumor shrank. The median clinical follow-up was 5 years. The trigeminal pain improved or disappeared in 5 patients, and of these, 4 cases stopped their medication and one decreased it. The hemifacial spasm resolved in 2 patients who were able to stop their medication. Facial palsy developed in 1 patient and improved with conservative treatment. Transient diplopia was also reported in 2 cases. Conclusion: Gamma knife radiosurgery provides good clinical control for cerebellopontine angle epidermoid tumors. PMID:29184709

  20. Comparison of penumbra regions produced by ancient Gamma knife model C and Gamma ART 6000 using Monte Carlo MCNP6 simulation.

    PubMed

    Banaee, Nooshin; Asgari, Sepideh; Nedaie, Hassan Ali

    2018-07-01

    The accuracy of penumbral measurements in radiotherapy is pivotal because dose planning computers require accurate data to adequately modeling the beams, which in turn are used to calculate patient dose distributions. Gamma knife is a non-invasive intracranial technique based on principles of the Leksell stereotactic system for open deep brain surgeries, invented and developed by Professor Lars Leksell. The aim of this study is to compare the penumbra widths of Leksell Gamma Knife model C and Gamma ART 6000. Initially, the structure of both systems were simulated by using Monte Carlo MCNP6 code and after validating the accuracy of simulation, beam profiles of different collimators were plotted. MCNP6 beam profile calculations showed that the penumbra values of Leksell Gamma knife model C and Gamma ART 6000 for 18, 14, 8 and 4 mm collimators are 9.7, 7.9, 4.3, 2.6 and 8.2, 6.9, 3.6, 2.4, respectively. The results of this study showed that since Gamma ART 6000 has larger solid angle in comparison with Gamma Knife model C, it produces better beam profile penumbras than Gamma Knife model C in the direct plane. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Gamma Knife treatment of low-grade gliomas in children.

    PubMed

    Ekşi, Murat Şakir; Yılmaz, Baran; Akakın, Akın; Toktaş, Zafer Orkun; Kaur, Ahmet Cemil; Demir, Mustafa Kemal; Kılıç, Türker

    2015-11-01

    Low-grade gliomas have good overall survival rates in pediatric patients compared to adults. There are some case series that reported the effectiveness and safety of Gamma Knife radiosurgery, yet they are limited in number of patients. We aimed to review the relevant literature for pediatric low-grade glial tumors treated with stereotactic radiosurgery, specifically Gamma Knife radiosurgery, and to present an exemplary case. A 6-year-old boy was admitted to clinic due to head trauma. He was alert, cooperative, and had no obvious motor or sensorial deficit. A head CT scan depicted a hypodense zone at the right caudate nucleus. The brain magnetic resonance imaging (MRI) depicted a mass lesion at the same location. A stereotactic biopsy was performed. Histopathological diagnosis was low-grade astrocytoma (grade II, World Health Organization (WHO) classification, 2007). Gamma Knife radiosurgery was applied to the tumor bed. Tumor volume was 21.85 cm(3). Fourteen gray was given to 50% isodose segment of the lesion (maximal dose of 28 Gy). The tumor has disappeared totally in 4 months, and the patient was tumor-free 21 months after the initial treatment. The presented literature review represents mostly single-center experiences with different patient and treatment characteristics. Accordingly, a mean/median margin dose of 11.3-15 Gy with Gamma Knife radiosurgery (GKRS) is successful in treatment of pediatric and adult low-grade glial tumor patients. However, prospective studies with a large cohort of pediatric patients should be conducted to make a more comprehensive conclusion for effectiveness and safety of GKRS in pediatric low-grade glial tumors.

  2. The gamma knife in ophthalmology. Part One--Uveal melanoma.

    PubMed

    Wygledowska-Promieńska, Dorota; Jurys, Małgorzata; Wilczyński, Tomasz; Drzyzga, Łukasz

    2014-01-01

    The Gamma Knife was designed by Lars Leksell in the early 1950's. It gave rise to a new discipline of medicine--stereotactic radiosurgery. Primarily dedicated to neurosurgery, the Gamma Knife has become an alternative, widely used surgery technique. According to Elekta's statistics, approximately 60,000 people are treated with Leksell Gamma Knife every year and it is the most extensively studied stereotactic radiosurgery system in the world. The Leksell Gamma Knife can also be used in ophthalmology. The gamma ray beam concentration enables effective treatment of uveal melanoma, choroidal hemangioma, orbital tumors or even choroidal neovascularization. The virtue of Leksell Gamma Knife is its extreme precision, non-invasiveness and the possibility of outpatient treatment, which significantly reduces costs and diminishes post-operative complications. Innovative solutions shorten a single session to a minimum, which is very comfortable and safe for both staff and patients. Advantages and possible side effects of gamma knife radiosurgery are well-documented in the professional literature. The objective of this review is to present the recognized applications of Leksell Gamma Knife in ophthalmology.

  3. Cost analysis of Gamma Knife stereotactic radiosurgery.

    PubMed

    Griffiths, Alison; Marinovich, Luke; Barton, Michael B; Lord, Sarah J

    2007-01-01

    Stereotactic radiosurgery (SRS) is used to treat intracranial lesions and vascular malformations as an addition or replacement to whole brain radiotherapy and microsurgery. SRS can be delivered by hardware and software appended to standard linear accelerators (Linacs) or by dedicated systems such as Gamma Knife, which has been proposed as a more accurate and user friendly technology. Internationally, dedicated systems have been funded, despite limitations in evidence. However, some countries including Australia have not recommended additional reimbursement for dedicated systems. This study compares the costs of Linac radiosurgery with Gamma Knife radiosurgery. Due to limited evidence on comparative effects, the economic analysis was restricted to a cost evaluation. The base-case analysis assumed a modified Linac was used only to treat SRS patients. However, because a modified Linac could be used to treat other radiotherapy patients, a second analysis assumed spare time was used to meet other radiotherapy needs, and Linac capital costs were apportioned according to SRS use. The incremental cost of Gamma Knife versus a modified Linac was estimated as AU$209 per patient. This result is sensitive to variations in assumptions. A second analysis proportioning capital costs according to SRS use showed that Gamma Knife may cost up to AU$1673 more per patient. Gamma Knife may be cost competitive only if demand for SRS services is high enough to fully use equipment working time. However, given low patient demand and competing radiotherapy needs, Gamma Knife appears more costly and further evidence of survival or quality of life advantages may be required to justify reimbursement.

  4. Forward treatment planning techniques to reduce the normalization effect in Gamma Knife radiosurgery.

    PubMed

    Cheng, Hao-Wen; Lo, Wei-Lun; Kuo, Chun-Yuan; Su, Yu-Kai; Tsai, Jo-Ting; Lin, Jia-Wei; Wang, Yu-Jen; Pan, David Hung-Chi

    2017-11-01

    In Gamma Knife forward treatment planning, normalization effect may be observed when multiple shots are used for treating large lesions. This effect can reduce the proportion of coverage of high-value isodose lines within targets. The aim of this study was to evaluate the performance of forward treatment planning techniques using the Leksell Gamma Knife for the normalization effect reduction. We adjusted the shot positions and weightings to optimize the dose distribution and reduce the overlap of high-value isodose lines from each shot, thereby mitigating the normalization effect during treatment planning. The new collimation system, Leksell Gamma Knife Perfexion, which contains eight movable sectors, provides an additional means to reduce the normalization effect by using composite shots. We propose different techniques in forward treatment planning that can reduce the normalization effect. Reducing the normalization effect increases the coverage proportion of higher isodose lines within targets, making the high-dose region within targets more uniform and increasing the mean dose to targets. Because of the increase in the mean dose to the target after reducing the normalization effect, we can set the prescribed marginal dose at a higher isodose level and reduce the maximum dose, thereby lowering the risk of complications. © 2017 Shuang Ho Hospital-Taipei Medical University. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  5. Out of field dose during Gamma Knife treatment: a paediatric case study

    NASA Astrophysics Data System (ADS)

    Moutrie, V.; Grace, M.; Izard, M. A.; Fuller, J. W.

    2017-01-01

    An 11-year-old girl with an arteriovenous malformation (AVM) was referred for Gamma Knife treatment. As this would be the first paediatric treatment in Australia, additional investigations were undertaken into out of field dose to assure the best possible long term outcome for the patient. A phantom was constructed from water equivalent materials to simulate the patient. A target volume was defined to emulate the size and location of the AVM visible in diagnostic images. An ionisation chamber and EBT3 Gafchromic film were used to record absorbed dose at strategic points both on the surface and at depth within the phantom. On the day of treatment, EBT3 Gafchromic film was used to conduct in vivo dosimetry. The pre-treatment phantom measurements matched the planning system for the cranial section (the only modelled section) and no measurable dose above background was detected in the extracranial sites. In vivo measurements of the lenses returned doses of up to 2 cGy for imaging and 8 cGy for treatment which was also consistent with the planned dose. Dose to the thyroid, chest and abdomen was not measurable above background.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Benmakhlouf, H; Kraepelien, T; Forander, P

    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 withmore » 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

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Massager, Nicolas; Abeloos, Laurence; Devriendt, Daniel

    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 radiosurgicalmore » 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.« less

  8. Radiosurgery with the world's first fully robotized Leksell Gamma Knife PerfeXion in clinical use: a 200-patient prospective, randomized, controlled comparison with the Gamma Knife 4C.

    PubMed

    Régis, Jean; Tamura, Manabu; Guillot, Cécile; Yomo, Shoji; Muraciolle, Xavier; Nagaje, Mariko; Arka, Yasser; Porcheron, Denis

    2009-02-01

    The world's first Leksell Gamma Knife PerfeXion (Elekta Instrument AB, Stockholm, Sweden) for radiosurgery of the head and neck became operational at Timone University Hospital in Marseille on July 10, 2006. To allow strict evaluation of the capabilities, advantages, disadvantages, and limitations of this new technology, patients were enrolled in a prospective, randomized trial. In 66 working days, between July 10 and December 20, 2006, 363 patients were treated by gamma knife surgery at Timone University Hospital, Marseille. Of these patients, 200 were eligible for the comparative prospective study (inclusion criteria were informed consent obtained, tumor or vascular indication, and no previous radiosurgery or radiotherapy). In accordance with the blinded randomization process, 100 patients were treated with the Leksell Gamma Knife 4C (Elekta Instrument AB) and Gamma Knife 100 (Elekta Instrument AB) with the Leksell Gamma Knife PerfeXion. Dose planning parameters, dosimetry measurements on the patient's body, workflow, patient comfort, quality assurance procedure, and a series of other treatment-related parameters were systematically and prospectively evaluated in both arms of the trial. No technical failure of the treatment procedure was encountered. The new dose-planning system led to the use of composite shots in 39.4% of the patients. The median number of different collimator sizes used was larger with the PerfeXion than with the 4C (2 and 1, respectively). The mean number of isocenters used was lower (10.67 and 13.08, respectively). The median total treatment time was significantly shorter with the PerfeXion (40 and 60 minutes, respectively), but there was no significant difference in the median radiation time (34.02 and 33.40 minutes, respectively). The procedure was performed using only a single run in 98.99% of the PerfeXion cases and in 42% of the 4C cases. Collision risk on the 4C forced us to change the frame gamma angle for at least 1 shot in 24% of

  9. Failure modes and effects analysis (FMEA) for Gamma Knife radiosurgery.

    PubMed

    Xu, Andy Yuanguang; Bhatnagar, Jagdish; Bednarz, Greg; Flickinger, John; Arai, Yoshio; Vacsulka, Jonet; Feng, Wenzheng; Monaco, Edward; Niranjan, Ajay; Lunsford, L Dade; Huq, M Saiful

    2017-11-01

    Gamma Knife radiosurgery is a highly precise and accurate treatment technique for treating brain diseases with low risk of serious error that nevertheless could potentially be reduced. We applied the AAPM Task Group 100 recommended failure modes and effects analysis (FMEA) tool to develop a risk-based quality management program for Gamma Knife radiosurgery. A team consisting of medical physicists, radiation oncologists, neurosurgeons, radiation safety officers, nurses, operating room technologists, and schedulers at our institution and an external physicist expert on Gamma Knife was formed for the FMEA study. A process tree and a failure mode table were created for the Gamma Knife radiosurgery procedures using the Leksell Gamma Knife Perfexion and 4C units. Three scores for the probability of occurrence (O), the severity (S), and the probability of no detection for failure mode (D) were assigned to each failure mode by 8 professionals on a scale from 1 to 10. An overall risk priority number (RPN) for each failure mode was then calculated from the averaged O, S, and D scores. The coefficient of variation for each O, S, or D score was also calculated. The failure modes identified were prioritized in terms of both the RPN scores and the severity scores. The established process tree for Gamma Knife radiosurgery consists of 10 subprocesses and 53 steps, including a subprocess for frame placement and 11 steps that are directly related to the frame-based nature of the Gamma Knife radiosurgery. Out of the 86 failure modes identified, 40 Gamma Knife specific failure modes were caused by the potential for inappropriate use of the radiosurgery head frame, the imaging fiducial boxes, the Gamma Knife helmets and plugs, the skull definition tools as well as other features of the GammaPlan treatment planning system. The other 46 failure modes are associated with the registration, imaging, image transfer, contouring processes that are common for all external beam radiation therapy

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

    PubMed

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

    2016-01-01

    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 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. 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.

  11. Multistage stereotactic radiosurgery for large cerebral arteriovenous malformations using the Gamma Knife platform.

    PubMed

    Ding, Chuxiong; Hrycushko, Brian; Whitworth, Louis; Li, Xiang; Nedzi, Lucien; Weprin, Bradley; Abdulrahman, Ramzi; Welch, Babu; Jiang, Steve B; Wardak, Zabi; Timmerman, Robert D

    2017-10-01

    Radiosurgery is an established technique to treat cerebral arteriovenous malformations (AVMs). Obliteration of larger AVMs (> 10-15 cm 3 or diameter > 3 cm) in a single session is challenging with current radiosurgery platforms due to toxicity. We present a novel technique of multistage stereotactic radiosurgery (SRS) for large intracranial arteriovenous malformations (AVM) using the Gamma Knife system. Eighteen patients with large (> 10-15 cm 3 or diameter > 3 cm) AVMs, which were previously treated using a staged SRS technique on the Cyberknife platform, were retrospectively selected for this study. The AVMs were contoured and divided into 3-8 subtargets to be treated sequentially in a staged approach at half to 4 week intervals. The prescription dose ranged from 15 Gy to 20 Gy, depending on the subtarget number, volume, and location. Gamma Knife plans using multiple collimator settings were generated and optimized. The coordinates of each shot from the initial plan covering the total AVM target were extracted based on their relative positions within the frame system. The shots were regrouped based on their location with respect to the subtarget contours to generate subplans for each stage. The delivery time of each shot for a subtarget was decay corrected with 60 Co for staging the treatment course to generate the same dose distribution as that planned for the total AVM target. Conformality indices and dose-volume analysis were performed to evaluate treatment plans. With the shot redistribution technique, the composite dose for the multistaged treatment of multiple subtargets is equivalent to the initial plan for total AVM target. Gamma Knife plans resulted in an average PTV coverage of 96.3 ± 0.9% and a PITV of 1.23 ± 0.1. The resulting Conformality indices, V 12Gy and R 50 dose spillage values were 0.76 ± 0.05, 3.4 ± 1.8, and 3.1 ± 0.5 respectively. The Gamma Knife system can deliver a multistaged conformal dose to treat large AVMs when correcting for

  12. Leksell Gamma Knife radiosurgery of the jugulotympanic glomus tumor: long-term results.

    PubMed

    Liscak, Roman; Urgosik, Dusan; Chytka, Tomas; Simonova, Gabriela; Novotny, Josef; Vymazal, Josef; Guseynova, Khumar; Vladyka, Vilibald

    2014-12-01

    Glomus tumors usually display indolent behavior, and the effectiveness of radiation in stopping their growth can be assessed after long-term follow-up. Currently only midterm results of radiosurgery are available, so the authors included patients treated by Gamma Knife at least 10 years ago in this study to obtain a perspective of long-term results. During the period from 1992 to 2003, the Gamma Knife was used to treat 46 patients with glomus tumors. The age of the patients ranged from 21 to 79 years (median 56 years). Gamma Knife radiosurgery was the primary treatment in 17 patients (37%). Open surgery preceded radiosurgery in 46% of cases, embolization in 17%, and fractionated radiotherapy in 4%. The volume of the tumor ranged from 0.2 to 24.3 cm(3) (median 3.6 cm(3)). The minimal dose to the tumor margin ranged between 10 and 30 Gy (median 20 Gy). One patient was lost for follow-up after radiosurgery. Clinical follow-up was available in 45 patients and 44 patients were followed with MRI in a follow-up period that ranged from 12 to 217 months (median 118 months). Neurological deficits improved in 19 (42%) of 45 patients and deteriorated in 2 patients (4%). Tumor size decreased in 34 (77%) of 44 patients with imaging follow-up, while an increase in volume was observed in 1 patient (2%) 182 months after radiosurgery and Gamma Knife treatment was repeated. One patient underwent another Gamma Knife treatment for secondary induced meningioma close to the glomus tumor 98 months after initial radiosurgical treatment. Seven patients died 22-96 months after radiosurgery (median 48 months), all for unrelated reasons. Radiosurgery has proved to be a safe treatment with a low morbidity rate and a reliable long-term antiproliferative effect.

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

    PubMed

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

    2006-09-07

    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.

  15. Emerging Indications for Fractionated Gamma Knife Radiosurgery.

    PubMed

    McTyre, Emory; Helis, Corbin A; Farris, Michael; Wilkins, Lisa; Sloan, Darrell; Hinson, William H; Bourland, J Daniel; Dezarn, William A; Munley, Michael T; Watabe, Kounosuke; Xing, Fei; Laxton, Adrian W; Tatter, Stephen B; Chan, Michael D

    2017-02-01

    Gamma Knife radiosurgery (GKRS) allows for the treatment of intracranial tumors with a high degree of dose conformality and precision. There are, however, certain situations wherein the dose conformality of GKRS is desired, but single session treatment is contraindicated. In these situations, a traditional pin-based GKRS head frame cannot be used, as it precludes fractionated treatment. To report our experience in treating patients with fractionated GKRS using a relocatable, noninvasive immobilization system. Patients were considered candidates for fractionated GKRS if they had one or more of the following indications: a benign tumor >10 cc in volume or abutting the optic pathway, a vestibular schwannoma with the intent of hearing preservation, or a tumor previously irradiated with single fraction GKRS. The immobilization device used for all patients was the Extend system (Leksell Gamma Knife Perfexion, Elekta, Kungstensgatan, Stockholm). We identified 34 patients treated with fractionated GKRS between August 2013 and February 2015. There were a total of 37 tumors treated including 15 meningiomas, 11 pituitary adenomas, 6 brain metastases, 4 vestibular schwannomas, and 1 hemangioma. At last follow-up, all 21 patients treated for perioptic tumors had stable or improved vision and all 4 patients treated for vestibular schwannoma maintained serviceable hearing. No severe adverse events were reported. Fractionated GKRS was well-tolerated in the treatment of large meningiomas, perioptic tumors, vestibular schwannomas with intent of hearing preservation, and in reirradiation of previously treated tumors.

  16. Emerging Indications for Fractionated Gamma Knife Radiosurgery

    PubMed Central

    McTyre, Emory; Helis, Corbin A.; Farris, Michael; Wilkins, Lisa; Sloan, Darrell; Hinson, William H.; Bourland, J. Daniel; Dezarn, William. A.; Munley, Michael T.; Watabe, Kounosuke; Xing, Fei; Laxton, Adrian W.; Tatter, Stephen B.; Chan, Michael D.

    2016-01-01

    BACKGROUND Gamma Knife radiosurgery (GKRS) allows for the treatment of intracranial tumors with a high degree of dose conformality and precision. There are, however, certain situations wherein the dose conformality of GKRS is desired, but single session treatment is contraindicated. In these situations, a traditional pin-based GKRS head frame cannot be used, as it precludes fractionated treatment. OBJECTIVE To report our experience in treating patients with fractionated GKRS using a relocatable, noninvasive immobilization system. METHODS Patients were considered candidates for fractionated GKRS if they had one or more of the following indications: a benign tumor >10 cc in volume or abutting the optic pathway, a vestibular schwannoma with the intent of hearing preservation, or a tumor previously irradiated with single fraction GKRS. The immobilization device used for all patients was the Extend system (Leksell Gamma Knife Perfexion, Elekta, Kungstensgatan, Stockholm). RESULTS We identified 34 patients treated with fractionated GKRS between August 2013 and February 2015. There were a total of 37 tumors treated including 15 meningiomas, 11 pituitary adenomas, 6 brain metastases, 4 vestibular schwannomas, and 1 hemangioma. At last follow-up, all 21 patients treated for perioptic tumors had stable or improved vision and all 4 patients treated for vestibular schwannoma maintained serviceable hearing. No severe adverse events were reported. CONCLUSION Fractionated GKRS was well-tolerated in the treatment of large meningiomas, perioptic tumors, vestibular schwannomas with intent of hearing preservation, and in reirradiation of previously treated tumors. PMID:28536486

  17. Long-Term Results of Gamma Knife Radiosurgery for Intracranial Meningioma

    PubMed Central

    Jang, Chang Ki; Jung, Hyun Ho; Chang, Jong Hee; Chang, Jin Woo; Park, Yong Gou

    2015-01-01

    Background The predominant treatment modality for meningioma is surgical resection. However, gamma knife radiosurgery is also an important treatment modality for meningioma that is small or cannot be completely removed because of its location. In this study, we evaluated the effectiveness and long-term results of radiosurgical treatment for meningioma in our institution. Methods We studied 628 patients (130 men and 498 women) who underwent gamma knife radiosurgery for intracranial meningioma, which is radiologically diagnosed, from Jan 2008 to Nov 2012. We included patients with single lesion meningioma, and followed up after 6 months with imaging, and then at 24 months with a clinical examination. Patients with high-grade meningioma or multiple meningiomas were excluded. We analyzed each of the factors associated with progression free survival. The median patient's age was 56.8 years. Maximal dosage was 27.8 Gy and marginal dosage was 13.9 Gy. Results The overall tumor control rate was 95%. Twenty-eight patients (4.4%) showed evidence of tumor recurrence. Ninety-eight patients (15%) developed peritumoral edema (PTE) after gamma-knife surgery; two of them (2%) underwent surgical resections due to PTE. Nine patients had craniotomy and tumor removal after gamma knife surgery. Conclusion Gamma knife surgery for intracranial meningioma has proven to be a safe and effective treatment tool with successful long-term outcomes. Gamma knife radiosurgery can be especially effective in cases of remnant meningioma after surgical resection or where PTE is not present. PMID:26605265

  18. Long-Term Results of Gamma Knife Radiosurgery for Intracranial Meningioma.

    PubMed

    Jang, Chang Ki; Jung, Hyun Ho; Chang, Jong Hee; Chang, Jin Woo; Park, Yong Gou; Chang, Won Seok

    2015-10-01

    The predominant treatment modality for meningioma is surgical resection. However, gamma knife radiosurgery is also an important treatment modality for meningioma that is small or cannot be completely removed because of its location. In this study, we evaluated the effectiveness and long-term results of radiosurgical treatment for meningioma in our institution. We studied 628 patients (130 men and 498 women) who underwent gamma knife radiosurgery for intracranial meningioma, which is radiologically diagnosed, from Jan 2008 to Nov 2012. We included patients with single lesion meningioma, and followed up after 6 months with imaging, and then at 24 months with a clinical examination. Patients with high-grade meningioma or multiple meningiomas were excluded. We analyzed each of the factors associated with progression free survival. The median patient's age was 56.8 years. Maximal dosage was 27.8 Gy and marginal dosage was 13.9 Gy. The overall tumor control rate was 95%. Twenty-eight patients (4.4%) showed evidence of tumor recurrence. Ninety-eight patients (15%) developed peritumoral edema (PTE) after gamma-knife surgery; two of them (2%) underwent surgical resections due to PTE. Nine patients had craniotomy and tumor removal after gamma knife surgery. Gamma knife surgery for intracranial meningioma has proven to be a safe and effective treatment tool with successful long-term outcomes. Gamma knife radiosurgery can be especially effective in cases of remnant meningioma after surgical resection or where PTE is not present.

  19. Gamma knife radiosurgery in movement disorders: Indications and limitations.

    PubMed

    Higuchi, Yoshinori; Matsuda, Shinji; Serizawa, Toru

    2017-01-01

    Functional radiosurgery has advanced steadily during the past half century since the development of the gamma knife technique for treating intractable cancer pain. Applications of radiosurgery for intracranial diseases have increased with a focus on understanding radiobiology. Currently, the use of gamma knife radiosurgery to ablate deep brain structures is not widespread because visualization of the functional targets remains difficult despite the increased availability of advanced neuroimaging technology. Moreover, most existing reports have a small sample size or are retrospective. However, increased experience with intraoperative neurophysiological evaluations in radiofrequency thalamotomy and deep brain stimulation supports anatomical and neurophysiological approaches to the ventralis intermedius nucleus. Two recent prospective studies have promoted the clinical application of functional radiosurgery for movement disorders. For example, unilateral gamma knife thalamotomy is a potential alternative to radiofrequency thalamotomy and deep brain stimulation techniques for intractable tremor patients with contraindications for surgery. Despite the promising efficacy of gamma knife thalamotomy, however, these studies did not include sufficient follow-up to confirm long-term effects. Herein, we review the radiobiology literature, various techniques, and the treatment efficacy of gamma knife radiosurgery for patients with movement disorders. Future research should focus on randomized controlled studies and long-term effects. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

  20. Surgery or gamma -knife for the treatment of arteriovenous malformations?

    PubMed

    Shigeno, T; Atsuchi, M; Tanaka, J; Goto, K; Ogata, N

    2000-09-01

    Decision making for either surgery or gamma-knife for the treatment of arteriovenous malformations (AVMs) cannot be uniform. The skill of the neurosurgeon in operating on AVMs is now being compared with that of the gamma-knife. The decision varies from case to case and is to be taken by the neurosurgeon. This report presents three cases in which such decision making was not easy. Case 1 was a non-ruptured cingulate AVM of 2.5 cm diameter in the cingulate cortex. The operative field was anticipated to be very narrow between the parietal bridging veins. Case 2 was a tiny ruptured AVM in the speech-motor area which was buried underneath the cortex. Case 3 was a large ruptured thalamo-stiriate-capsular AVM with feeders from the anterior and posterior choroidal arteries. All cases were operated without serious morbidity. A combination of pre-operative intravascular surgery (cases 1 and 3) or postoperative gamma-knife (case 3) was adopted. In conclusion, there is no unitary rule to decide on surgery or gamma-knife for the treatment of AVMs. It depends on what good or harm the responsible surgeon or the gamma-knife does.

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

    PubMed

    Lee, John Y K; Sandhu, Sukhmeet; Miller, Denise; Solberg, Timothy; Dorsey, Jay F; Alonso-Basanta, Michelle

    2015-10-01

    Gamma Knife radiosurgery (GKRS) utilizes cobalt-60 as its radiation source, and thus dose rate varies as the fixed source decays over its half-life of approximately 5.26 years. This natural decay results in increasing treatment times when delivering the same cumulative dose. It is also possible, however, that the biological effective dose may change based on this dose rate even if the total dose is kept constant. Because patients are generally treated in a uniform manner, radiosurgery for trigeminal neuralgia (TN) represents a clinical model whereby biological efficacy can be tested. The authors hypothesized that higher dose rates would result in earlier and more complete pain relief but only if measured with a sensitive pain assessment tool. One hundred thirty-three patients were treated with the Gamma Knife Model 4C unit at a single center by a single neurosurgeon during a single cobalt life cycle from January 2006 to May 2012. All patients were treated with 80 Gy with a single 4-mm isocenter without blocking. Using an output factor of 0.87, dose rates ranged from 1.28 to 2.95 Gy/min. The Brief Pain Inventory (BPI)-Facial was administered before the procedure and at the first follow-up office visit 1 month from the procedure (mean 1.3 months). Phone calls were made to evaluate patients after their procedures as part of a retrospective study. Univariate and multivariate linear regression was performed on several independent variables, including sex, age in deciles, diagnosis, follow-up duration, prior surgery, and dose rate. In the short-term analysis (mean 1.3 months), patients' self-reported pain intensity at its worst was significantly correlated with dose rate on multivariate analysis (p = 0.028). Similarly, patients' self-reported interference with activities of daily living was closely correlated with dose rate on multivariate analysis (p = 0.067). A 1 Gy/min decrease in dose rate resulted in a 17% decrease in pain intensity at its worst and a 22% decrease

  2. Technical Note: PRESAGE three-dimensional dosimetry accurately measures Gamma Knife output factors

    PubMed Central

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

    2014-01-01

    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 two-dimensional 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. PMID:25368961

  3. 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

  4. SU-F-SPS-10: The Dosimetric Comparison of GammaKnife and Cyberknife Treatment Plans for Brain SRS Treatment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sanli, E; Mabhouti, H; Cebe, M

    Purpose: Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made. Methods: Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis. The dose distribution were calculated using TMR 10 algorithm. The treatment planning for the same target weremore » also done for Cyberknife M6 machine using Multiplan (TPS) with Monte Carlo algorithm. Using the same film batch, the net OD to dose calibration curve was obtained using both machine by delivering 0- 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution were measured using EBT3 film dosimeter. The measured and calculated doses were compared. Results: The dose distribution in the target and 2 cm beyond the target edge were calculated on TPSs and measured using EBT3 film. For cyberknife treatment plans, the gamma analysis passing rates between measured and calculated dose distributions were 99.2% and 96.7% for target and peripheral region of target respectively. For gammaknife treatment plans, the gamma analysis passing rates were 98.9% and 93.2% for target and peripheral region of target respectively. Conclusion: The study shows that dosimetrically comparable plans are achievable with Cyberknife and GammaKnife. Although TMR 10 algorithm predicts the target dose.« less

  5. Independent Monte-Carlo dose calculation for MLC based CyberKnife radiotherapy

    NASA Astrophysics Data System (ADS)

    Mackeprang, P.-H.; Vuong, D.; Volken, W.; Henzen, D.; Schmidhalter, D.; Malthaner, M.; Mueller, S.; Frei, D.; Stampanoni, M. F. M.; Dal Pra, A.; Aebersold, D. M.; Fix, M. K.; Manser, P.

    2018-01-01

    This work aims to develop, implement and validate a Monte Carlo (MC)-based independent dose calculation (IDC) framework to perform patient-specific quality assurance (QA) for multi-leaf collimator (MLC)-based CyberKnife® (Accuray Inc., Sunnyvale, CA) treatment plans. The IDC framework uses an XML-format treatment plan as exported from the treatment planning system (TPS) and DICOM format patient CT data, an MC beam model using phase spaces, CyberKnife MLC beam modifier transport using the EGS++ class library, a beam sampling and coordinate transformation engine and dose scoring using DOSXYZnrc. The framework is validated against dose profiles and depth dose curves of single beams with varying field sizes in a water tank in units of cGy/Monitor Unit and against a 2D dose distribution of a full prostate treatment plan measured with Gafchromic EBT3 (Ashland Advanced Materials, Bridgewater, NJ) film in a homogeneous water-equivalent slab phantom. The film measurement is compared to IDC results by gamma analysis using 2% (global)/2 mm criteria. Further, the dose distribution of the clinical treatment plan in the patient CT is compared to TPS calculation by gamma analysis using the same criteria. Dose profiles from IDC calculation in a homogeneous water phantom agree within 2.3% of the global max dose or 1 mm distance to agreement to measurements for all except the smallest field size. Comparing the film measurement to calculated dose, 99.9% of all voxels pass gamma analysis, comparing dose calculated by the IDC framework to TPS calculated dose for the clinical prostate plan shows 99.0% passing rate. IDC calculated dose is found to be up to 5.6% lower than dose calculated by the TPS in this case near metal fiducial markers. An MC-based modular IDC framework was successfully developed, implemented and validated against measurements and is now available to perform patient-specific QA by IDC.

  6. Prediction of obliteration after gamma knife surgery for cerebral arteriovenous malformations.

    PubMed

    Karlsson, B; Lindquist, C; Steiner, L

    1997-03-01

    To define the factors of importance for the obliteration of cerebral arteriovenous malformations (AVMs), thus making a prediction of the probability for obliteration possible. In 945 AVMs of a series of 1319 patients treated with the gamma knife during 1970 to 1990, the relationship between patient, AVMs, and treatment parameters on the one hand and the obliteration of the nidus on the other was analyzed. The obliteration rate increased both with increased minimum (lowest periphery) and average dose and decreased with increased AVM volume. The minimum dose to the AVMs was the decisive dose factor for the treatment result. The higher the minimum dose, the higher the chance for total obliteration. The curve illustrating this relation increased logarithmically to a value of 87%. A higher average dose shortened the latency to AVM obliteration. For the obliterated cases, the larger the malformation, the lower the minimum dose used. This prompted us to relate the obliteration rate to the product minimum dose (AVM volume)1/3 (K index). The obliteration rate increased linearly with the K index up to a value of approximately 27, and for higher K values, the obliteration rate had a constant value of approximately 80%. For the group of 273 cases treated with a minimum dose of at least 25 Gy, the obliteration rate at the study end point (defined as 2-yr latency) was 80% (95% confidence interval = 75-85%). If obliterations that occurred beyond the end point are included, the obliteration rate increased to 85% (81-89%). The probability of obliteration of AVMs after gamma knife surgery is related both to the lowest dose to the AVMs and the AVM volume, and it can be predicted using the K index.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Constanzo, Julie; Paquette, Benoit; Charest, Gabriel

    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 brainmore » 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.« less

  8. γTools: A modular multifunction phantom for quality assurance in GammaKnife treatments.

    PubMed

    Calusi, Silvia; Noferini, Linhsia; Marrazzo, Livia; Casati, Marta; Arilli, Chiara; Compagnucci, Antonella; Talamonti, Cinzia; Scoccianti, Silvia; Greto, Daniela; Bordi, Lorenzo; Livi, Lorenzo; Pallotta, Stefania

    2017-11-01

    We present the γTools, a new phantom designed to assess geometric and dosimetric accuracy in Gamma Knife treatments, together with first tests and results of applications. The phantom is composed of two modules: the imaging module, a regular grid of 1660 control points to evaluate image distortions and image registration result and the dosimetry module for delivered dose distribution measurements. The phantom is accompanied by a MatLab routine for image distortions quantification. Dose measurement are performed with Gafchromic films fixed between two inserts and placed in various positions and orientations inside the dosimetry module thus covering a volume comparable to the full volume of a head. Tests performed to assess the accuracy and precision of the imaging module demonstrated sub-millimetric values. As an example of possible applications, the phantom was employed to measure image distortions of two MRI scanners and to perform dosimetric studies of single shots delivered to homogeneous and heterogeneous materials. Due to the phantom material, the measured absolute dose do not correspond to the planned dose; doses comparisons are thus carried out between normalized dose distributions. Finally, an end-to-end test was carried out in the treatment of a neuroma-like target which resulted in a 100% gamma passing rate (2% local, 2 mm) and a distance between the real target perimeter and the prescription isodose centroids of about 1 mm. The tests demonstrate that the proposed phantom is suitable to assess both the geometrical and relative dosimetric accuracy of Gamma Knife radiosurgery treatments. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  9. Dose calculation accuracy of the Monte Carlo algorithm for CyberKnife compared with other commercially available dose calculation algorithms.

    PubMed

    Sharma, Subhash; Ott, Joseph; Williams, Jamone; Dickow, Danny

    2011-01-01

    Monte Carlo dose calculation algorithms have the potential for greater accuracy than traditional model-based algorithms. This enhanced accuracy is particularly evident in regions of lateral scatter disequilibrium, which can develop during treatments incorporating small field sizes and low-density tissue. A heterogeneous slab phantom was used to evaluate the accuracy of several commercially available dose calculation algorithms, including Monte Carlo dose calculation for CyberKnife, Analytical Anisotropic Algorithm and Pencil Beam convolution for the Eclipse planning system, and convolution-superposition for the Xio planning system. The phantom accommodated slabs of varying density; comparisons between planned and measured dose distributions were accomplished with radiochromic film. The Monte Carlo algorithm provided the most accurate comparison between planned and measured dose distributions. In each phantom irradiation, the Monte Carlo predictions resulted in gamma analysis comparisons >97%, using acceptance criteria of 3% dose and 3-mm distance to agreement. In general, the gamma analysis comparisons for the other algorithms were <95%. The Monte Carlo dose calculation algorithm for CyberKnife provides more accurate dose distribution calculations in regions of lateral electron disequilibrium than commercially available model-based algorithms. This is primarily because of the ability of Monte Carlo algorithms to implicitly account for tissue heterogeneities, density scaling functions; and/or effective depth correction factors are not required. Copyright © 2011 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

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

    PubMed Central

    Vivekanandhan, S.; Kale, S.S.; Rath, G.K.; Senthilkumaran, S.; Thulkar, S.; Subramani, V.; Laviraj, M.A.; Bisht, R.K.; 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=0.5 mm x 0.5 mm, 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. PACS number: 87.53.Ly, 87.55.‐x, 87

  11. [Alterations of glial fibrillary acidic protein in rat brain after gamma knife irradiation].

    PubMed

    Ma, Z M; Jiang, B; Ma, J R

    2001-08-28

    To study glial fibrillary acidic protein (GFAP) immunoreactivity in different time and water content of the rat brain treated with gamma knife radiotherapy and to understand the alteration course of the brain lesion after a single high dose radiosurgical treatment. In the brains of the normal rats were irradiated by gamma knife with 160 Gy-high dose. The irradiated rats were then killed on the 1st day, 7th day, 14th day, and 28th day after radiotherapy, respectively. The positive cells of GFAP in brain tissue were detected by immunostaining; the water content of the brain tissue was measured by microgravimetry. The histological study of the irradiated brain tissue was performed with H.E. and examined under light microscope. The numbers of GFAP-positive astrocytes began to increase on the 1st day after gamma knife irradiation. It was enlarged markedly in the number and size of GFAP-stained astrocytes over the irradiated areas. Up to the 28th day, circumscribed necrosis foci (4 mm in diameter) was seen in the central area of the target. In the brain tissue around the necrosis, GFAP-positive astrocytes significantly increased (P < 0.01, compared with the control group). The swelling of cells in irradiated region was observed on the 1st day; after irradiation endothelial cells degenerated and red blood cells escaped from blood vessel on the 7th day; leakage of Evans blue dye was observed in the target region on the 14th day. There was a significant decrease of specific gravity in the irradiated brain tissue the 14th and 28th day after irradiation. The results suggest that GFAP can be used as a marker for the radiation-induced brain injury. The brain edema and disruption of brain-blood barrier can be occurred during the acute stage after irradiation.

  12. The role of diffusion tensor imaging tractography for Gamma Knife thalamotomy planning.

    PubMed

    Gomes, João Gabriel Ribeiro; Gorgulho, Alessandra Augusta; de Oliveira López, Amanda; Saraiva, Crystian Wilian Chagas; Damiani, Lucas Petri; Pássaro, Anderson Martins; Salvajoli, João Victor; de Oliveira Siqueira, Ludmila; Salvajoli, Bernardo Peres; De Salles, Antônio Afonso Ferreira

    2016-12-01

    OBJECTIVE The role of tractography in Gamma Knife thalamotomy (GK-T) planning is still unclear. Pyramidal tractography might reduce the risk of radiation injury to the pyramidal tract and reduce motor complications. METHODS In this study, the ventralis intermedius nucleus (VIM) targets of 20 patients were bilaterally defined using Iplannet Stereotaxy Software, according to the anterior commissure-posterior commissure (AC-PC) line and considering the localization of the pyramidal tract. The 40 targets and tractography were transferred as objects to the GammaPlan Treatment Planning System (GP-TPS). New targets were defined, according to the AC-PC line in the functional targets section of the GP-TPS. The target offsets required to maintain the internal capsule (IC) constraint of < 15 Gy were evaluated. In addition, the strategies available in GP-TPS to maintain the minimum conventional VIM target dose at > 100 Gy were determined. RESULTS A difference was observed between the positions of both targets and the doses to the IC. The lateral (x) and the vertical (z) coordinates were adjusted 1.9 mm medially and 1.3 mm cranially, respectively. The targets defined considering the position of the pyramidal tract were more medial and superior, based on the constraint of 15 Gy touching the object representing the IC in the GP-TPS. The best strategy to meet the set constraints was 90° Gamma angle (GA) with automatic shaping of dose distribution; this was followed by 110° GA. The worst GA was 70°. Treatment time was substantially increased by the shaping strategy, approximately doubling delivery time. CONCLUSIONS Routine use of DTI pyramidal tractography might be important to fine-tune GK-T planning. DTI tractography, as well as anisotropy showing the VIM, promises to improve Gamma Knife functional procedures. They allow for a more objective definition of dose constraints to the IC and targeting. DTI pyramidal tractography introduced into the treatment planning may reduce the

  13. The current role of Gamma Knife radiosurgery in the management of intracranial haemangiopericytoma.

    PubMed

    Spina, Alfio; Boari, Nicola; Gagliardi, Filippo; Donofrio, Carmine A; Franzin, Alberto; Mortini, Pietro

    2016-04-01

    Haemangiopericytomas (HPCs) are rare tumours characterised by aggressive behaviour with tendency to local recurrence and to metastasise. WHO grade II and grade III tumours show different progression-free survival and overall survival rates. Gross total tumour resection is still considered the treatment of choice. Adjuvant radiation therapies represent an option in the treatment strategy regardless the extent of resection. Based on this consideration, Gamma Knife radiosurgery has been introduced either as a primary treatment or as an adjuvant treatment for residual or recurrent tumours. A systematic search was performed on PubMed, Web of Science and Google Scholar for clinical series reporting Gamma Knife radiosurgery, Cyberknife and Linear Accelerator (LINAC) for the management of intracranial HPCs. Fourteen studies focusing on the effects of Gamma Knife radiosurgery for intracranial HPCs were included. Four studies reported data on Cyberknife radiosurgery and LINAC. A total of 208 patients harbouring 366 tumours have been reported. Patient's features, radiosurgical treatment characteristics and follow-up data of the pertinent literature have been critically revised. Gamma Knife radiosurgery and the other radiosurgical techniques represent a feasible and effective therapy in the management of HPCs. Tumour control and survival rate are comparable to those reported for radiotherapy. Further studies should be focused to define the exact role of Gamma Knife radiosurgery in the management of HPCs.

  14. SU-E-T-86: A Systematic Method for GammaKnife SRS Fetal Dose Estimation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Geneser, S; Paulsson, A; Sneed, P

    Purpose: Estimating fetal dose is critical to the decision-making process when radiation treatment is indicated during pregnancy. Fetal doses less than 5cGy confer no measurable non-cancer developmental risks but can produce a threefold increase in developing childhood cancer. In this study, we estimate fetal dose for a patient receiving Gamma Knife stereotactic radiosurgery (GKSRS) treatment and develop a method to estimate dose directly from plan details. Methods: A patient underwent GKSRS on a Perfexion unit for eight brain metastases (two infratentorial and one brainstem). Dose measurements were performed using a CC13, head phantom, and solid water. Superficial doses to themore » thyroid, sternum, and pelvis were measured using MOSFETs during treatment. Because the fetal dose was too low to accurately measure, we obtained measurements proximally to the isocenter, fitted to an exponential function, and extrapolated dose to the fundus of the uterus, uterine midpoint, and pubic synthesis for both the preliminary and delivered plans. Results: The R-squared fit for the delivered doses was 0.995. The estimated fetal doses for the 72 minute preliminary and 138 minute delivered plans range from 0.0014 to 0.028cGy and 0.07 to 0.38cGy, respectively. MOSFET readings during treatment were just above background for the thyroid and negligible for all inferior positions. The method for estimating fetal dose from plan shot information was within 0.2cGy of the measured values at 14cm cranial to the fetal location. Conclusion: Estimated fetal doses for both the preliminary and delivered plan were well below the 5cGy recommended limit. Due to Pefexion shielding, internal dose is primarily governed by attenuation and drops off exponentially. This is the first work that reports fetal dose for a GK Perfexion unit. Although multiple lesions were treated and the duration of treatment was long, the estimated fetal dose remained very low.« less

  15. Effect of the gamma knife treatment on the trigeminal nerve root in Chinese patients with primary trigeminal neuralgia.

    PubMed

    Song, Zhi-Xiu; Qian, Wei; Wu, Yu-Quan; Sun, Fang-Jie; Fei, Jun; Huang, Run-Sheng; Fang, Jing-Yu; Wu, Cai-Zhen; An, You-Ming; Wang, Daxin; Yang, Jun

    2014-01-01

    To understand the mechanism of the gamma knife treating the trigeminal neuralgia. Using the MASEP-SRRS type gamma knife treatment system, 140 Chinese patients with trigeminal neuralgia (NT) were treated in our hospital from 2002 to 2010, in which the pain relief rate reached 95% and recurrence rate was 3% only. We investigated the effect of the gamma knife treatment on the trigeminal nerve root in 20 Chinese patients with primary trigeminal neuralgia by the magnetic resonance imager (MRI) observation. 1) The cross-sectional area of trigeminal nerve root became smaller and MRI signals were lower in the treatment side than those in the non-treatment side after the gamma knife treatment of primary trigeminal neuralgia; 2) in the treatment side, the cross-sectional area of the trigeminal nerve root decreased significantly after the gamma knife treatment; 3) there was good correlation between the clinical improvement and the MRI findings; and 4) the straight distance between the trigeminal nerve root and the brainstem did not change after the gamma knife treatment. The pain relief induced the gamma knife radiosurgery might be related with the atrophy of the trigeminal nerve root in Chinese patients with primary trigeminal neuralgia.

  16. Feasibility Study on Applying Radiophotoluminescent Glass Dosimeters for CyberKnife SRS Dose Verification

    PubMed Central

    Hsu, Shih-Ming; Hung, Chao-Hsiung; Liao, Yi-Jen; Fu, Hsiao-Mei; Tsai, Jo-Ting

    2017-01-01

    CyberKnife is one of multiple modalities for stereotactic radiosurgery (SRS). Due to the nature of CyberKnife and the characteristics of SRS, dose evaluation of the CyberKnife procedure is critical. A radiophotoluminescent glass dosimeter was used to verify the dose accuracy for the CyberKnife procedure and validate a viable dose verification system for CyberKnife treatment. A radiophotoluminescent glass dosimeter, thermoluminescent dosimeter, and Kodak EDR2 film were used to measure the lateral dose profile and percent depth dose of CyberKnife. A Monte Carlo simulation for dose verification was performed using BEAMnrc to verify the measured results. This study also used a radiophotoluminescent glass dosimeter coupled with an anthropomorphic phantom to evaluate the accuracy of the dose given by CyberKnife. Measurements from the radiophotoluminescent glass dosimeter were compared with the results of a thermoluminescent dosimeter and EDR2 film, and the differences found were less than 5%. The radiophotoluminescent glass dosimeter has some advantages in terms of dose measurements over CyberKnife, such as repeatability, stability, and small effective size. These advantages make radiophotoluminescent glass dosimeters a potential candidate dosimeter for the CyberKnife procedure. This study concludes that radiophotoluminescent glass dosimeters are a promising and reliable dosimeter for CyberKnife dose verification with clinically acceptable accuracy within 5%. PMID:28046056

  17. Review of the poster "Dosimetric comparison of gamma knife radiosurgery vs. 125I plaque brachytherapy in a cohort of choroidal melanomas".

    PubMed

    Odell, Kelly R

    2009-01-01

    Historically, treatment for choroidal melanomas was surgical enucleation. Currently, treatment methods such as stereotactic radiosurgery and brachytherapy are being used to spare the eye. The poster "Dosimetric Comparison of Gamma Knife Radiosurgery vs. I-125 Plaque Brachytherapy in a Cohort of Choroidal Melanomas" presented at ASTRO 2007 by Anderson et al. provides a comparison of these methods. The dose to disk, fovea and lens in 29 patients from a simulated I-125 treatment and a delivered Gamma Knife radiosurgery was compared. Thirty Gy was prescribed to the 50% Isodose line in the radiosurgery and 85 Gy was prescribed to the apex of the tumor in the I-125 simulation. It was found that the Gamma Knife spares the disk better in 59% of the tumors, including those >or=6.5 mm in height; spares the fovea better in 69% of the tumors, including those >or=5.5 mm; and spares lens better in only 30% of the tumors, with no distinction in size. Tumor location was not taken into account for this study, which could explain the variations in smaller tumors. For larger tumors, gamma knife will protect most organs at risk more effectively. This study shows how a tumor's parameters can be used in selecting treatment modality.

  18. Angiomatous lesion and delayed cyst formation after gamma knife surgery for intracranial meningioma: case report and review of literatures.

    PubMed

    Liu, Zhiyong; He, Min; Chen, Hongxu; Liu, Yi; Li, Qiang; Li, Lin; Li, Jin; Chen, Haifeng; Xu, Jianguo

    2015-01-01

    Gamma Knife has become a major therapeutic method for intracranial meningiomas, vascular malformations and schwannomas with exact effect. In recent years an increasing number of delayed complications after Gamma Knife surgery have been reported, such as secondary tumors, cystic changes or cyst formation. But angiomatous lesion and delayed cyst formation after Gamma Knife for intracranial lesion has rarely been reported. Here we report the first case of angiomatous lesion and delayed cyst formation following Gamma Knife for intracranial meningioma and discuss its pathogenesis.

  19. WE-A-304-02: Strategies and Technologies for Cranial Radiosurgery Planning: Gamma Knife

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schlesinger, D.

    2015-06-15

    The high fractional doses, stringent requirements for accuracy and precision, and surgical perspective characteristic of intracranial radiosurgery create considerations for treatment planning which are distinct from most other radiotherapy procedures. This session will introduce treatment planning techniques specific to two popular intracranial SRS modalities: Gamma Knife and MLC-based Linac. The basic treatment delivery characteristics of each device will be reviewed with a focus on how those characteristics determine the paradigm used for treatment planning. Basic techniques for treatment planning will be discussed, including considerations such as isodose selection, target and organ-at-risk definition, quality indices, and protection of critical structures. Futuremore » directions for SRS treatment planning will also be discussed. Learning Objectives: Introduce the basic physical principles of intracranial radiosurgery and how they are realized in the treatment planning paradigms for Gamma Knife and Linac radiosurgery. Demonstrate basic treatment planning techniques. Discuss metrics for evaluating SRS treatment plan quality. Discuss recent and future advances in SRS treatment planning. D. Schlesinger receives research support from Elekta, AB.« less

  20. Clinical outcomes of gamma knife radiosurgery in the salvage treatment of patients with recurrent high-grade glioma.

    PubMed

    Elaimy, Ameer L; Mackay, Alexander R; Lamoreaux, Wayne T; Demakas, John J; Fairbanks, Robert K; Cooke, Barton S; Lamm, Andrew F; Lee, Christopher M

    2013-12-01

    Previously published randomized evidence did not report a survival advantage for patients diagnosed with grade IV glioma who were treated with stereotactic radiosurgery followed by external beam radiation therapy and chemotherapy when compared to patients treated with external beam radiation therapy and chemotherapy alone. In recent years, gamma knife radiosurgery has become increasingly popular as a salvage treatment modality for patients diagnosed with recurrent high-grade glioma. The purpose of this article is to review the efficacy of gamma knife radiosurgery for patients who suffer from this malignancy. Retrospective, prospective, and randomized clinical studies published between the years 2000 and 2012 analyzing gamma knife radiosurgery for patients with high-grade glioma were reviewed. After assessing patient age, Karnofsky performance status, tumor histology, and extent of resection, gamma knife radiosurgery is a viable, minimally invasive treatment option for patients diagnosed with recurrent high-grade glioma. The available prospective and retrospective evidence suggests that gamma knife radiosurgery provides patients with a high local tumor control rate and a median survival after tumor recurrence ranging from 13 to 26 months. Gamma knife radiosurgery followed by chemotherapy for recurrent high-grade glioma may provide select patients with increased levels of survival. However, further investigation into this matter is needed due to the limited number of published reports. Additional clinical research is also needed to analyze the efficacy and radiation-related toxicities of fractionated gamma knife radiosurgery due to its potential to limit treatment-associated morbidity. Gamma knife radiosurgery is a safe and effective treatment option for select patients diagnosed with recurrent high-grade glioma. Although treatment outcomes have improved, further evidence in the form of phase III randomized trials is needed to assess the durability of treating

  1. Gamma knife radiosurgery for vestibular schwannomas: tumor control and functional preservation in 70 patients.

    PubMed

    Arthurs, Benjamin J; Lamoreaux, Wayne T; Mackay, Alexander R; Demakas, John J; Giddings, Neil A; Fairbanks, Robert K; Cooke, Barton S; Elaimy, Ameer L; Peressini, Ben; Lee, Christopher M

    2011-06-01

    We present the previously unreported outcomes of 70 patients treated with Gamma knife radiosurgery for vestibular schwannoma (VS), including comprehensive analysis of clinical outcomes and the effects of lower marginal doses. We performed a retrospective study of patients treated for VS at Gamma knife of Spokane between 2003 and 2008. Endpoints measured include tumor control, hearing preservation, and facial nerve preservation, including the effect of tumor size and marginal dose. Statistical analysis was performed with Wilcoxon signed-rank test, paired Student t test, Mann-Whitney U test, Kendall's rank correlation, Fisher exact test, and Liddell's exact χ(2) test for matched pairs. With a mean follow-up of 26 months, 93.8% of tumors either shrank or remained static after receiving a mean marginal dose of 12.7 Gy. Tumor control was independent of marginal dose or tumor size. Hearing preservation was achieved in 64% of patients with serviceable function before the treatment. Hearing changes were independent of dose or tumor size. Preservation of good facial nerve function was achieved in 95% of patients. Post-treatment hydrocephalus occurred in 4.4% of patients, but no other significant morbidities were elucidated. In the treatment of VS, contemporary radiosurgical techniques and the use of marginal doses below 13 Gy offer excellent tumor control, at high rates relative to surgical intervention. These findings are independent of marginal dose and tumor size. Patients should be informed about the benefits and risks of radiosurgery and microsurgery before choosing an intervention. Further analysis of post-treatment outcomes should be encouraged as follow-up times increase and the treatment protocols continue to evolve.

  2. Gamma knife surgery-induced ependymoma after the treatment of meningioma - a case report.

    PubMed

    Wang, Ke; Pan, Li; Che, Xiaoming; Lou, Meiqing

    2012-01-01

    Gamma knife surgery is widely used for a number of neurological disorders. However, little is known about its long-term complications such as carcinogenic risks. Here, we present a case of a radiosurgery-induced ependymoma by gamma knife surgery for the treatment of a spinal meningioma in a 7-year-old patient. In light of reviewing the previous reports, we advocate high caution in making young patients receive this treatment.

  3. Gamma Knife radiosurgery in pituitary adenomas: Why, who, and how to treat?

    PubMed

    Castinetti, Frederic; Brue, Thierry

    2010-08-01

    Pituitary adenomas are benign tumors that can be either secreting (acromegaly, Cushing's disease, prolactinomas) or non-secreting. Transsphenoidal neurosurgery is the gold standard treatment; however, it is not always effective. Gamma Knife radiosurgery is a specific modality of stereotactic radiosurgery, a precise radiation technique. Several studies reported the efficacy and low risk of adverse effects induced by this technique: in secreting pituitary adenomas, hypersecretion is controlled in about 50% of cases and tumor volume is stabilized or decreased in 80-90% of cases, making Gamma Knife a valuable adjunctive or first-line treatment. As hormone levels decrease progressively, the main drawback is the longer time to remission (12-60 months), requiring an additional treatment during this period. Hypopituitarism is the main side effect, observed in 20-40% cases. Gamma Knife is thus useful in the therapeutic algorithms of pituitary adenomas in well-defined indications, mainly low secreting small lesions well identified on magnetic resonance imaging (MRI).

  4. A microcosting study of microsurgery, LINAC radiosurgery, and gamma knife radiosurgery in meningioma patients

    PubMed Central

    van Putten, Erik; Nijdam, Wideke M.; Hanssens, Patrick; Beute, Guus N.; Nowak, Peter J.; Dirven, Clemens M.; Hakkaart-van Roijen, Leona

    2010-01-01

    The aim of the present study is to determine and compare initial treatment costs of microsurgery, linear accelerator (LINAC) radiosurgery, and gamma knife radiosurgery in meningioma patients. Additionally, the follow-up costs in the first year after initial treatment were assessed. Cost analyses were performed at two neurosurgical departments in The Netherlands from the healthcare providers’ perspective. A total of 59 patients were included, of whom 18 underwent microsurgery, 15 underwent LINAC radiosurgery, and 26 underwent gamma knife radiosurgery. A standardized microcosting methodology was employed to ensure that the identified cost differences would reflect only actual cost differences. Initial treatment costs, using equipment costs per fraction, were €12,288 for microsurgery, €1,547 for LINAC radiosurgery, and €2,412 for gamma knife radiosurgery. Higher initial treatment costs for microsurgery were predominantly due to inpatient stay (€5,321) and indirect costs (€4,350). LINAC and gamma knife radiosurgery were equally expensive when equipment was valued per treatment (€2,198 and €2,412, respectively). Follow-up costs were slightly, but not significantly, higher for microsurgery compared with LINAC and gamma knife radiosurgery. Even though initial treatment costs were over five times higher for microsurgery compared with both radiosurgical treatments, our study gives indications that the relative cost difference may decrease when follow-up costs occurring during the first year after initial treatment are incorporated. This reinforces the need to consider follow-up costs after initial treatment when examining the relative costs of alternative treatments. PMID:20526795

  5. Single-session Gamma Knife radiosurgery for optic pathway/hypothalamic gliomas.

    PubMed

    El-Shehaby, Amr M N; Reda, Wael A; Abdel Karim, Khaled M; Emad Eldin, Reem M; Nabeel, Ahmed M

    2016-12-01

    OBJECTIVE Because of their critical and central location, it is deemed necessary to fractionate when considering irradiating optic pathway/hypothalamic gliomas. Stereotactic fractionated radiotherapy is considered safer when dealing with gliomas in this location. In this study, the safety and efficacy of single-session stereotactic radiosurgery for optic pathway/hypothalamic gliomas were reviewed. METHODS Between December 2004 and June 2014, 22 patients with optic pathway/hypothalamic gliomas were treated by single-session Gamma Knife radiosurgery. Twenty patients were available for follow-up for a minimum of 1 year after treatment. The patients were 5 to 43 years (median 16 years) of age. The tumor volume was 0.15 to 18.2 cm 3 (median 3.1 cm 3 ). The prescription dose ranged from 8 to 14 Gy (median 11.5 Gy). RESULTS The mean follow-up period was 43 months. Five tumors involved the optic nerve only, and 15 tumors involved the chiasm/hypothalamus. Two patients died during the follow-up period. The tumors shrank in 12 cases, remained stable in 6 cases, and progressed in 2 cases, thereby making the tumor control rate 90%. Vision remained stable in 12 cases, improved in 6 cases, and worsened in 2 cases in which there was tumor progression. Progression-free survival was 83% at 3 years. CONCLUSIONS The initial results indicate that single-session Gamma Knife radiosurgery is a safe and effective treatment option for optic pathway/hypothalamic gliomas.

  6. A simplified model of the source channel of the Leksell GammaKnife tested with PENELOPE.

    PubMed

    Al-Dweri, Feras M O; Lallena, Antonio M; Vilches, Manuel

    2004-06-21

    Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife. The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3 degrees with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photon trajectories reaching the output helmet collimators at (x, v, z = 236 mm) show strong correlations between rho = (x2 + y2)(1/2) and their polar angle theta, on one side, and between tan(-1)(y/x) and their azimuthal angle phi, on the other. This enables us to propose a simplified model which treats the full source channel as a mathematical collimator. This simplified model produces doses in good agreement with those found for the full geometry. In the region of maximal dose, the relative differences between both calculations are within 3%, for the 18 and 14 mm helmets, and 10%, for the 8 and 4 mm ones. Besides, the simplified model permits a strong reduction (larger than a factor 15) in the computational time.

  7. Dependence of normal brain integral dose and normal tissue complication probability on the prescription isodose values for γ-knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Ma, Lijun

    2001-11-01

    A recent multi-institutional clinical study suggested possible benefits of lowering the prescription isodose lines for stereotactic radiosurgery procedures. In this study, we investigate the dependence of the normal brain integral dose and the normal tissue complication probability (NTCP) on the prescription isodose values for γ-knife radiosurgery. An analytical dose model was developed for γ-knife treatment planning. The dose model was commissioned by fitting the measured dose profiles for each helmet size. The dose model was validated by comparing its results with the Leksell gamma plan (LGP, version 5.30) calculations. The normal brain integral dose and the NTCP were computed and analysed for an ensemble of treatment cases. The functional dependence of the normal brain integral dose and the NCTP versus the prescribing isodose values was studied for these cases. We found that the normal brain integral dose and the NTCP increase significantly when lowering the prescription isodose lines from 50% to 35% of the maximum tumour dose. Alternatively, the normal brain integral dose and the NTCP decrease significantly when raising the prescribing isodose lines from 50% to 65% of the maximum tumour dose. The results may be used as a guideline for designing future dose escalation studies for γ-knife applications.

  8. Worldwide variance in the potential utilization of Gamma Knife radiosurgery.

    PubMed

    Hamilton, Travis; Dade Lunsford, L

    2016-12-01

    OBJECTIVE The role of Gamma Knife radiosurgery (GKRS) has expanded worldwide during the past 3 decades. The authors sought to evaluate whether experienced users vary in their estimate of its potential use. METHODS Sixty-six current Gamma Knife users from 24 countries responded to an electronic survey. They estimated the potential role of GKRS for benign and malignant tumors, vascular malformations, and functional disorders. These estimates were compared with published disease epidemiological statistics and the 2014 use reports provided by the Leksell Gamma Knife Society (16,750 cases). RESULTS Respondents reported no significant variation in the estimated use in many conditions for which GKRS is performed: meningiomas, vestibular schwannomas, and arteriovenous malformations. Significant variance in the estimated use of GKRS was noted for pituitary tumors, craniopharyngiomas, and cavernous malformations. For many current indications, the authors found significant variance in GKRS users based in the Americas, Europe, and Asia. Experts estimated that GKRS was used in only 8.5% of the 196,000 eligible cases in 2014. CONCLUSIONS Although there was a general worldwide consensus regarding many major indications for GKRS, significant variability was noted for several more controversial roles. This expert opinion survey also suggested that GKRS is significantly underutilized for many current diagnoses, especially in the Americas. Future studies should be conducted to investigate health care barriers to GKRS for many patients.

  9. Completion of Gamma Knife radiosurgery for AVM treatment after unplanned interruption-technical note.

    PubMed

    Raman, Hari S; Santanam, Lakshmi; Vellimana, Ananth K; Drzymala, Robert E; Tsien, Christina I; Zipfel, Gregory J

    2018-02-17

    Gamma Knife radiosurgery is an established technique for non-urgent treatment of various intracranial pathologies. Intra-procedural dislodgement of the stereotactic frame is an uncommon occurrence that could lead to abortion of ongoing treatment and necessitate more invasive treatment strategies. In this case report, we describe a novel method for resumption of Gamma Knife treatment after an unplanned intra-procedural interruption. The case example involves a radiosurgical treatment of a Spetzler-Martin grade I arteriovenous malformation. Our technique involves integration of scans and coordinate systems from two imaging sessions using the composite isodose line to resolve translational differences, thereby limiting delivery of remaining shots to the untreated region of the lesion. MRI follow-up at 13 months showed a reduction in the nidus size with no evidence of any radiation injury to the surrounding brain parenchyma. We believe this technique will allow care teams to effectively salvage interrupted Gamma Knife procedures and reduce progression to more invasive treatment options.

  10. Stereotaxic gamma knife surgery in treatment of critically located pilocytic astrocytoma: preliminary result

    PubMed Central

    Hafez, Raef FA

    2007-01-01

    Background Low-grade gliomas are uncommon primary brain tumors, located more often in the posterior fossa, optic pathway, and brain stem and less commonly in the cerebral hemispheres. Case presentations Two patients with diagnosed recurrent cystic pilocytic astrocytoma critically located within the brain (thalamic and brain stem) were treated with gamma knife surgery. Gamma knife surgery (GKS) did improve the patient's clinical condition very much which remained stable later on. Progressive reduction on the magnetic resonance imaging (MRI) studies of the solid part of the tumor and almost disappearance of the cystic component was achieved within the follow-up period of 36 months in the first case with the (thalamic located lesion) and 22 months in the second case with the (brain stem located lesion). Conclusion Gamma knife surgery represents an alternate tool in the treatment of recurrent and/or small postoperative residual pilocytic astrocytoma especially if they are critically located PMID:17394660

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

    PubMed

    Linskey, M E

    2000-12-01

    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

  12. 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

  13. Optimal Shape of a Gamma-ray Collimator: single vs double knife edge

    NASA Astrophysics Data System (ADS)

    Metz, Albert; Hogenbirk, Alfred

    2017-09-01

    Gamma-ray collimators in nuclear waste scanners are used for selecting a narrow vertical segment in activity measurements of waste vessels. The system that is used by NRG uses tapered slit collimators of both the single and double knife edge type. The properties of these collimators were investigated by means of Monte Carlo simulations. We found that single knife edge collimators are highly preferable for a conservative estimate of the activity of the waste vessels. These collimators show much less dependence on the angle of incidence of the radiation than double knife edge collimators. This conclusion also applies to cylindrical collimators of the single knife edge type, that are generally used in medical imaging spectroscopy.

  14. A simplified model of the source channel of the Leksell GammaKnife® tested with PENELOPE

    NASA Astrophysics Data System (ADS)

    Al-Dweri, Feras M. O.; Lallena, Antonio M.; Vilches, Manuel

    2004-06-01

    Monte Carlo simulations using the code PENELOPE have been performed to test a simplified model of the source channel geometry of the Leksell GammaKnife®. The characteristics of the radiation passing through the treatment helmets are analysed in detail. We have found that only primary particles emitted from the source with polar angles smaller than 3° with respect to the beam axis are relevant for the dosimetry of the Gamma Knife. The photon trajectories reaching the output helmet collimators at (x, y, z = 236 mm) show strong correlations between rgr = (x2 + y2)1/2 and their polar angle thgr, on one side, and between tan-1(y/x) and their azimuthal angle phgr, on the other. This enables us to propose a simplified model which treats the full source channel as a mathematical collimator. This simplified model produces doses in good agreement with those found for the full geometry. In the region of maximal dose, the relative differences between both calculations are within 3%, for the 18 and 14 mm helmets, and 10%, for the 8 and 4 mm ones. Besides, the simplified model permits a strong reduction (larger than a factor 15) in the computational time.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Massager, Nicolas, E-mail: nmassage@ulb.ac.be; Neurosurgery-Department, Hospital Erasme, Brussels; Lonneville, Sarah

    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), gradientmore » 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.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Flannery, Thomas; Department of Radiation Oncology, University of Pittsburgh School of Medicine and the University of Pittsburgh Medical Center, Pittsburgh, PA; Department of Neurosurgery, Royal Hospitals Trust, Belfast, Northern Ireland

    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 primarymore » 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.« less

  17. The safety and efficacy of gamma knife surgery in management of glomus jugulare tumor

    PubMed Central

    2010-01-01

    Background Glomus jugulare is a slowly growing, locally destructive tumor located in the skull base with difficult surgical access. The operative approach is, complicated by the fact that lesions may be both intra and extradural with engulfment of critical neurovascular structures. The tumor is frequently highly vascular, thus tumor resection entails a great deal of morbidity and not infrequent mortality. At timeslarge residual tumors are left behind. To decrease the morbidity associated with surgical resection of glomus jugulare, gamma knife surgery (GKS) was performed as an alternative in 13 patients to evaluate its safety and efficacy. Methods A retrospective review of 13 residual or unresectable glomus jagulare treated with GKS between 2004 and 2008.. Of these, 11 patients underwent GKS as the primary management and one case each was treated for postoperative residual disease and postembolization. The radiosurgical dose to the tumor margin ranged between 12-15 Gy. Results Post- gamma knife surgery and during the follow-up period twelve patients demonstrated neurological stability while clinical improvement was achieved in 5 patients. One case developed transient partial 7th nerve palsy that responded to medical treatment. In all patients radiographic MRI follow-up was obtained, the tumor size decreased in two cases and remained stable (local tumor control) in eleven patients. Conclusions Gamma knife surgery provids tumor control with a lowering of risk of developing a new cranial nerve injury in early follow-up period. This procedure can be safely used as a primary management tool in patients with glomus jugulare tumors, or in patients with recurrent tumors in this location. If long-term results with GKS are equally effective it will emerge as a good alternative to surgical resection. PMID:20819207

  18. Gamma Knife radiosurgery for glomus jugulare tumors: a single-center series of 75 cases.

    PubMed

    Ibrahim, Ramez; Ammori, Mohannad B; Yianni, John; Grainger, Alison; Rowe, Jeremy; Radatz, Matthias

    2017-05-01

    OBJECTIVE Glomus jugulare tumors are rare indolent tumors that frequently involve the lower cranial nerves (CNs). Complete resection can be difficult and associated with lower CN injury. Gamma Knife radiosurgery (GKRS) has established its role as a noninvasive alternative treatment option for these often formidable lesions. The authors aimed to review their experience at the National Centre for Stereotactic Radiosurgery, Sheffield, United Kingdom, specifically the long-term tumor control rate and complications of GKRS for these lesions. METHODS Clinical and radiological data were retrospectively reviewed for patients treated between March 1994 and December 2010. Data were available for 75 patients harboring 76 tumors. The tumors in 3 patients were treated in 2 stages. Familial and/or hereditary history was noted in 12 patients, 2 of whom had catecholamine-secreting and/or active tumors. Gamma Knife radiosurgery was the primary treatment modality in 47 patients (63%). The median age at the time of treatment was 55 years. The median tumor volume was 7 cm 3 , and the median radiosurgical dose to the tumor margin was 18 Gy (range 12-25 Gy). The median duration of radiological follow-up was 51.5 months (range 12-230 months), and the median clinical follow-up was 38.5 months (range 6-223 months). RESULTS The overall tumor control rate was 93.4% with low CN morbidity. Improvement of preexisting deficits was noted in 15 patients (20%). A stationary clinical course and no progression of symptoms were noted in 48 patients (64%). Twelve patients (16%) had new symptoms or progression of their preexisting symptoms. The Kaplan-Meier actuarial tumor control rate was 92.2% at 5 years and 86.3% at 10 years. CONCLUSIONS Gamma Knife radiosurgery offers a risk-versus-benefit treatment option with very low CN morbidity and stable long-term results.

  19. Iridium-Knife: Another knife in radiation oncology.

    PubMed

    Milickovic, Natasa; Tselis, Nikolaos; Karagiannis, Efstratios; Ferentinos, Konstantinos; Zamboglou, Nikolaos

    Intratarget dose escalation with superior conformity is a defining feature of three-dimensional (3D) iridium-192 ( 192 Ir) high-dose-rate (HDR) brachytherapy (BRT). In this study, we analyzed the dosimetric characteristics of interstitial 192 Ir HDR BRT for intrathoracic and cerebral malignancies. We examined the dose gradient sharpness of HDR BRT compared with that of linear accelerator-based stereotactic radiosurgery and stereotactic body radiation therapy, usually called X-Knife, to demonstrate that it may as well be called a Knife. Treatment plans for 10 patients with recurrent glioblastoma multiforme or intrathoracic malignancies, five of each entity, treated with X-Knife (stereotactic radiosurgery for glioblastoma multiforme and stereotactic body radiation therapy for intrathoracic malignancies) were replanned for simulated HDR BRT. For 3D BRT planning, we used identical structure sets and dose prescription as for the X-Knife planning. The indices for qualitative treatment plan analysis encompassed planning target volume coverage, conformity, dose falloff gradient, and the maximum dose-volume limits to different organs at risk. Volume coverage in HDR plans was comparable to that calculated for X-Knife plans with no statistically significant difference in terms of conformity. The dose falloff gradient-sharpness-of the HDR plans was considerably steeper compared with the X-Knife plans. Both 3D 192 Ir HDR BRT and X-Knife are effective means for intratarget dose escalation with HDR BRT achieving at least equal conformity and a steeper dose falloff at the target volume margin. In this sense, it can reasonably be argued that 3D 192 Ir HDR BRT deserves also to be called a Knife, namely Iridium-Knife. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  20. Repeat Gamma Knife Radiosurgery for Trigeminal Neuralgia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aubuchon, Adam C., E-mail: acaubuchon@gmail.com; Chan, Michael D.; Lovato, James F.

    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).more » 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.« less

  1. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Gamma Knife surgery for clival epidural-osseous dural arteriovenous fistulas.

    PubMed

    Lee, Cheng-Chia; Chen, Ching-Jen; Chen, Shao-Ching; Yang, Huai-Che; Lin, Chung Jung; Wu, Chih-Chun; Chung, Wen-Yuh; Guo, Wan-Yuo; Hung-Chi Pan, David; Shiau, Cheng-Ying; Wu, Hsiu-Mei

    2018-05-01

    OBJECTIVE Clival epidural-osseous dural arteriovenous fistula (DAVF) is often associated with a large nidus, multiple arterial feeders, and complex venous drainage. In this study the authors report the outcomes of clival epidural-osseous DAVFs treated using Gamma Knife surgery (GKS). METHODS Thirteen patients with 13 clival epidural-osseous DAVFs were treated with GKS at the authors' institution between 1993 and 2015. Patient age at the time of GKS ranged from 38 to 76 years (median 55 years). Eight DAVFs were classified as Cognard Type I, 4 as Type IIa, and 1 as Type IIa+b. The median treatment volume was 17.6 cm 3 (range 6.2-40.3 cm 3 ). The median prescribed margin dose was 16.5 Gy (range 15-18 Gy). Clinical and radiological follow-ups were performed at 6-month intervals. Patient outcomes after GKS were categorized as 1) complete improvement, 2) partial improvement, 3) stationary, and 4) progression. RESULTS All 13 patients demonstrated symptomatic improvement, and on catheter angiography 12 of the 13 patients had complete obliteration and 1 patient had partial obliteration. The median follow-up period was 26 months (range 14-186 months). The median latency period from GKS to obliteration was 21 months (range 8-186 months). There was no intracranial hemorrhage during the follow-up period, and no deaths occurred. Two adverse events were observed following treatment, and 2 patients required repeat GKS treatment with eventual complete obliteration. CONCLUSIONS Gamma Knife surgery offers a safe and effective primary or adjuvant treatment modality for complex clival epidural-osseous DAVFs. All patients in this case series demonstrated symptomatic improvement, and almost all patients attained complete obliteration.

  3. P11.10 Role of hydroxyurea as an adjuvant treatment after gamma knife radiosurgery for atypical (WHO grade II) meningiomas

    PubMed Central

    Abdel Karim, K.; El Shehaby, A.; Emad, R.; Reda, W.; El Mahdy, M.; Ghali, R.; Nabeel, A.

    2016-01-01

    Abstract Objective: The use of gamma knife radiosurgery in the treatment of atypical (WHO grade II) meningiomas has been reported in the past with highly variable degrees of success. The use of hydroxyurea as a radiation sensitizer as well as salvage chemotherapy in cancer patients is well established and was also used for treatment of recurrent and malignant meningiomas. In this study we investigated the effect of hydroxyurea administration after gamma knife radiosurgery for atypical (grade II) meningiomas on local tumor control and patient survival. Patients and methods: Between November 2008 and April 2014, thirty-five patients with pathologically proven atypical meningiomas were treated by gamma knife radiosurgery. We excluded patients who had received previous external beam radiotherapy. Twenty-three patients were given hydroxyurea after gamma knife treatment. The rest of the patients refused to take the treatment or were incompliant (were not included in the study). Of these 23, nineteen patients harboring 20 tumors were available for radiological and clinical follow up for a minimum of 2 years. Four patients were lost from follow up. Twenty tumors underwent 26 gamma knife procedures. Five tumors underwent staged treatment. The tumor volume was 0.6–38.3 cc (median 12.7 cc). The prescription dose/session ranged from 10 to 16 Gy (mean 14 Gy). The patients received a course of hydroxyurea (1000 mg/day) for one year after gamma knife treatment. The mean follow up period was 43 months (14–76 months). Results: Tumor control was achieved in 18 out of 20 tumors where 15 tumors shrank and 3 tumors remained stable with a tumor control rate of 90%. Tumor progression occurred in 2 patients (at 14 and 15 months). Transient edema was observed with 6 tumors which was temporary, and no G3 or G4 myelosuppression were recorded. Two patients died from progression of other tumors not included in the study after 3 and 6 years. Distant tumor progression (in another

  4. Initial experience with gamma knife surgery for endocrine ophthalmopathy.

    PubMed

    Antico, Julio C; Crovetto, Luis; Tenca, Eduardo; Artes, Carlos

    2005-01-01

    The aim of this study was to evaluate both the effectiveness and safety of the treatment of endocrine ophthalmopathy with gamma knife surgery (GKS). Five patients were included in a prospective study designed to assess the results of GKS of endocrine ophthalmopathy secondary to Graves disease. All the patients completed a 2-year follow-up period. During this period, the patients were evaluated both clinically and by means of additional methods, including computerized tomography and magnetic resonance imaging studies. The minimum dose delivered to the 50% isodose line was 6.5 Gy in all the patients. In all cases, a clinical improvement was observed. The best effect was seen in symptom regression related to soft-tissue involvement. No treatment-related side effects were detected. In light of the results obtained the authors consider that GKS may be a safe and effective way to treat endocrine ophthalmopathy.

  5. Long-term outcomes of Gamma Knife radiosurgery in patients with vestibular schwannomas.

    PubMed

    Murphy, Erin S; Barnett, Gene H; Vogelbaum, Michael A; Neyman, Gennady; Stevens, Glen H J; Cohen, Bruce H; Elson, Paul; Vassil, Andrew D; Suh, John H

    2011-02-01

    The authors sought to determine the long-term tumor control and side effects of Gamma Knife radiosurgery (GKRS) in patients with vestibular schwannomas (VS). One hundred seventeen patients with VS underwent GKRS between January 1997 and February 2003. At the time of analysis, at least 5 years had passed since GKRS in all patients. The mean patient age was 60.9 years. The mean maximal tumor diameter was 1.77 ± 0.71 cm. The mean tumor volume was 1.95 ± 2.42 ml. Eighty-two percent of lesions received 1300 cGy and 14% received 1200 cGy. The median dose homogeneity ratio was 1.97 and the median dose conformality ratio was 1.78. Follow-up included MR imaging or CT scanning approximately every 6-12 months. Rates of progression to surgery were calculated using the Kaplan-Meier method. Of the 117 patients in whom data were analyzed, 103 had follow-up MR or CT images and 14 patients were lost to follow-up. Fifty-three percent of patients had stable tumors and 37.9% had a radiographically documented response. Imaging-documented tumor progression was present in 8 patients (7.8%), but in 3 of these the lesion eventually stabilized. Only 5 patients required a neurosurgical intervention. The estimated 1-, 3-, and 5-year rates of progression to surgery were 1, 4.6, and 8.9%, respectively. One patient (1%) developed trigeminal neuropathy, 4 patients (5%) developed permanent facial neuropathy, 3 patients (4%) reported vertigo, and 7 patients (18%) had new gait imbalance following GKRS. Gamma Knife radiosurgery results in excellent local control rates with minimal toxicity for patients with VS. The authors recommend standardized follow-up to gain a better understanding of the long-term effects of GKRS.

  6. Gamma knife surgery for brainstem arteriovenous malformations.

    PubMed

    Yen, Chun-Po; Steiner, Ladislau

    2011-01-01

    To evaluate the long-term imaging and clinical outcomes of patients with brainstem arteriovenous malformations (AVMs) treated with Gamma Knife surgery (GKS). The study included 85 patients with brainstem AVMs undergoing GKS during the period 1989-2007. The locations of the nidi were the midbrain in 42 patients, pons in 31 patients, and medulla oblongata in 12 patients. The volume of the nidi ranged from 0.1-8.9 mL (median 1.4 mL, mean 1.9 mL), and the prescription dose ranged from 5-32 Gy (median 20 Gy, mean 19.9 Gy). After the initial Gamma procedure, 18 patients had repeat GKS for AVM residuals that were still patent. Two patients had a third GKS 7 years and 16 years after a failed repeat GKS. Clinical follow-up ranged from 24-252 months with a mean of 100 months (median 102 months) after the initial GKS. GKS yielded a total angiographic obliteration in 50 (58.8%) patients and subtotal obliteration in 4 (4.7%) patients. In 22 (25.9%) patients, the AVMs remained patent. In 9 patients (10.6%), no flow voids were observed on magnetic resonance imaging (MRI), but angiographic confirmation was unavailable. A small nidus volume and a high prescription dose were significantly associated with increased AVM obliteration rate. Radiation-induced changes developed in 34 patients (40%); 24 were asymptomatic, 1 patient had only headache, and 9 patients developed neurologic deficits. One patient developed a large cyst 6 years after GKS. Given the poor surgical outcome of brainstem AVMs, the results of 59% nidus obliteration and 6% permanent neurologic deficits make GKS a reasonable management of these difficult lesions. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. Gamma Knife Treatment of Brainstem Metastases

    PubMed Central

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

    2014-01-01

    The management of brainstem metastases is challenging. Surgical treatment is usually not an option, and chemotherapy is of limited utility. Stereotactic radiosurgery has emerged as a promising palliative treatment modality in these cases. The goal of this study is to assess our single institution experience treating brainstem metastases with Gamma Knife radiosurgery (GKRS). This retrospective chart review studied 41 patients with brainstem metastases treated with GKRS. The most common primary tumors were lung, breast, renal cell carcinoma, and melanoma. Median age at initial treatment was 59 years. Nineteen (46%) of the patients received whole brain radiation therapy (WBRT) prior to or concurrent with GKRS treatment. Thirty (73%) of the patients had a single brainstem metastasis. The average GKRS dose was 17 Gy. Post-GKRS overall survival at six months was 42%, at 12 months was 22%, and at 24 months was 13%. Local tumor control was achieved in 91% of patients, and there was one patient who had a fatal brain hemorrhage after treatment. Karnofsky performance score (KPS) >80 and the absence of prior WBRT were predictors for improved survival on multivariate analysis (HR 0.60 (p = 0.02), and HR 0.28 (p = 0.02), respectively). GKRS was an effective treatment for brainstem metastases, with excellent local tumor control. PMID:24886816

  8. Gamma Knife Radiosurgery for Uveal Metastases: Report of Three Cases and a Review of the Literature.

    PubMed

    Ares, William J; Tonetti, Daniel; Yu, Jenny Y; Monaco, Edward A; Flickinger, John C; Lunsford, L Dade

    2017-02-01

    Uveal metastases are ophthalmologic tumors that have historically been treated by fractionated external beam radiation therapy or invasive brachytherapy. The need for rapid response and less invasive management options led the authors to explore the use of Gamma Knife stereotactic radiosurgery (SRS) for this common problem. Interventional case series. To prevent eye movement during the procedure, all 3 patients underwent a retrobulbar anesthetic block followed by magnetic resonance imaging to detect the target. All tumors were treated in a single procedure using the 4C or Perfexion Gamma Knife. The tumors received a minimal tumor dose of 14-20 Gy. Two patients also underwent SRS for additional intracranial metastases. At follow-up, performed between 4 and 15 months after SRS, all 3 patients demonstrated a reduction in uveal tumor volumes. One patient developed decreased visual acuity secondary to radiation retinopathy. In this early experience, SRS was found to be an effective management option for uveal metastases associated with systemic cancer. Patients can be screened and treated effectively early after diagnosis using a joint approach between ophthalmologists and neurosurgeons. Systemic oncologic care can continue without interruption. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. A comparison of the convolution and TMR10 treatment planning algorithms for Gamma Knife® radiosurgery

    PubMed Central

    Wright, Gavin; Harrold, Natalie; Bownes, Peter

    2018-01-01

    Aims To compare the accuracies of the convolution and TMR10 Gamma Knife treatment planning algorithms, and assess the impact upon clinical practice of implementing convolution-based treatment planning. Methods Doses calculated by both algorithms were compared against ionisation chamber measurements in homogeneous and heterogeneous phantoms. Relative dose distributions calculated by both algorithms were compared against film-derived 2D isodose plots in a heterogeneous phantom, with distance-to-agreement (DTA) measured at the 80%, 50% and 20% isodose levels. A retrospective planning study compared 19 clinically acceptable metastasis convolution plans against TMR10 plans with matched shot times, allowing novel comparison of true dosimetric parameters rather than total beam-on-time. Gamma analysis and dose-difference analysis were performed on each pair of dose distributions. Results Both algorithms matched point dose measurement within ±1.1% in homogeneous conditions. Convolution provided superior point-dose accuracy in the heterogeneous phantom (-1.1% v 4.0%), with no discernible differences in relative dose distribution accuracy. In our study convolution-calculated plans yielded D99% 6.4% (95% CI:5.5%-7.3%,p<0.001) less than shot matched TMR10 plans. For gamma passing criteria 1%/1mm, 16% of targets had passing rates >95%. The range of dose differences in the targets was 0.2-4.6Gy. Conclusions Convolution provides superior accuracy versus TMR10 in heterogeneous conditions. Implementing convolution would result in increased target doses therefore its implementation may require a revaluation of prescription doses. PMID:29657896

  10. Gamma Knife radiosurgery for the management of nonfunctioning pituitary adenomas: a multicenter study.

    PubMed

    Sheehan, Jason P; Starke, Robert M; Mathieu, David; Young, Byron; Sneed, Penny K; Chiang, Veronica L; Lee, John Y K; Kano, Hideyuki; Park, Kyung-Jae; Niranjan, Ajay; Kondziolka, Douglas; Barnett, Gene H; Rush, Stephen; Golfinos, John G; Lunsford, L Dade

    2013-08-01

    Pituitary adenomas are fairly common intracranial neoplasms, and nonfunctioning ones constitute a large subgroup of these adenomas. Complete resection is often difficult and may pose undue risk to neurological and endocrine function. Stereotactic radiosurgery has come to play an important role in the management of patients with nonfunctioning pituitary adenomas. This study examines the outcomes after radiosurgery in a large, multicenter patient population. Under the auspices of the North American Gamma Knife Consortium, 9 Gamma Knife surgery (GKS) centers retrospectively combined their outcome data obtained in 512 patients with nonfunctional pituitary adenomas. Prior resection was performed in 479 patients (93.6%) and prior fractionated external-beam radiotherapy was performed in 34 patients (6.6%). The median age at the time of radiosurgery was 53 years. Fifty-eight percent of patients had some degree of hypopituitarism prior to radiosurgery. Patients received a median dose of 16 Gy to the tumor margin. The median follow-up was 36 months (range 1-223 months). Overall tumor control was achieved in 93.4% of patients at last follow-up; actuarial tumor control was 98%, 95%, 91%, and 85% at 3, 5, 8, and 10 years postradiosurgery, respectively. Smaller adenoma volume (OR 1.08 [95% CI 1.02-1.13], p = 0.006) and absence of suprasellar extension (OR 2.10 [95% CI 0.96-4.61], p = 0.064) were associated with progression-free tumor survival. New or worsened hypopituitarism after radiosurgery was noted in 21% of patients, with thyroid and cortisol deficiencies reported as the most common postradiosurgery endocrinopathies. History of prior radiation therapy and greater tumor margin doses were predictive of new or worsening endocrinopathy after GKS. New or progressive cranial nerve deficits were noted in 9% of patients; 6.6% had worsening or new onset optic nerve dysfunction. In multivariate analysis, decreasing age, increasing volume, history of prior radiation therapy, and

  11. SU-E-T-366: Estimation of Whole Body Dose From Cranial Irradiation From C and Perfexion Series Gamma Knife Units

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Srivastava, S; Indiana University School of Medicine, Indianapolis, IN, University Hospitals Case Medical Center, Cleaveland, OH; Andersen, A

    2015-06-15

    Purpose: The Leksell Gamma Knife (GK) B & C series contains 201 Cobalt-60 sources with a helmet. The new model, Perfexion uses 192 Cobalt-60 sources without a helmet; using IRIS system for collimation and stereotactic guidance to deliver SRS to brain tumors. Relative dose to extracranial organs at risk (OARs) is measured in phantom in this study for Perfexion and C-series GK. Materials & Methods: Measurements were performed in a Rando anthropomorphic phantom on both systems using a large ion chamber (Keithley-175) for each collimator. The Keithley-175 cc ion chamber was sandwiched between phantom slices at various locations in themore » phantom to correspond to different extracranial OARs (thyroid, heart, kidney, ovary and testis, etc.) The dose measurement was repeated with OSL detectors for each position and collimator. Results: A large variation is observed in the normalized dose between these two systems. The dose beyond the housing falls off exponentially for Perfexion. Dose beyond the C-series GK housing falls off exponentially from 0–20cm then remains relatively constant from 20–40cm and again falls off with distance but less rapidly. The variation of extracranial dose with distance for each collimator is found to be parallel to each other for both systems. Conclusion: Whole body dose is found to vary significantly between these systems. It is important to measure the extracranial dose, especially for young patients. It is estimated that dose falls off exponentially from the GK housing and is about 1% for large collimators at 75 cm. The dose is two-orders of magnitude smaller for the 4mm collimator. However, this small dose for patient may be significant radiologically.« less

  12. 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

  13. GammaKnife surgery: safety and the identity of users.

    PubMed

    Dinka, David; Nyce, James M; Timpka, Toomas

    2005-01-01

    In this study we investigated safety-related usability issues of an advanced medical technology, a radiosurgery system. We were interested in which criteria are important for users when a system's usability and safety is to be improved. The data collection was based on interviews and observations at three different sites where the Leksell GammaKnife is used. The analysis was qualitative. The main finding was that the user's identity or professional background has a significant impact both on how he or she views his or her role in the clinical setting, and on how he or she defines what improvements are necessary and general safety issues. In fact, the opinion even of users experienced in safety-related problems was highly influenced by how they related to the technology and its development. None of the users actually considered Leksell GammaKnife as lacking in safety, instead, their assessment was directed towards potential future system improvements. Our findings suggest that the importance of user identity or professional background cannot be neglected during the development of advanced technology. They also suggest that the user feedback should always be related to user background and identity in order to understand how important different issues are for particular users.

  14. Technical note: A 3D-printed phantom for routine accuracy check of Gamma Knife Icon HDMM system.

    PubMed

    Wu, Chuan; Radevic, Marlyn B; Glass, Jennifer S; Skubic, Stan E

    2018-05-23

    To report a novel 3D-printed device ("SH phantom") that is designed for routine accuracy check of the Gamma Knife Icon High Definition Motion Management (HDMM) system. SH phantom was designed using tinkerCAD software and printed on a commercial 3D printer. We evaluated the SH phantom on our Gamma Knife Icon unit regarding its usability and accuracy for routine HDMM QA. Single-axis and multiple-axis measurements validated the SH phantom design and implementation. An HDMM QA accuracy of 0.22 mm or better along single axis was found using SH phantom. The SH phantom proved to be a quick and simple tool to use to perform the HDMM system QA. The SH phantom was tested successfully and adopted by us as part of monthly QA for the Gamma Knife Icon. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  15. SU-F-P-15: Report On AAPM TG 178 Gamma Knife Dosimetry and Quality Assurance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Goetsch, S

    Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocolmore » modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers Conclusion: The full TG 178 report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and outline of possible dosimetry protocols. The report will be reviewed by the AAPM Working Group on Recommendations for Radiotherapy External Beam Quality Assurance and then by the AAPM Science Council before publication in Medical Physics. Consultant to Elekta, Inc.« less

  16. Adaptive fractionated stereotactic Gamma Knife radiotherapy of meningioma using integrated stereotactic cone-beam-CT and adaptive re-planning (a-gkFSRT).

    PubMed

    Stieler, F; Wenz, F; Abo-Madyan, Y; Schweizer, B; Polednik, M; Herskind, C; Giordano, F A; Mai, S

    2016-11-01

    The Gamma Knife Icon (Elekta AB, Stockholm, Sweden) allows frameless stereotactic treatment using a combination of cone beam computer tomography (CBCT), a thermoplastic mask system, and an infrared-based high-definition motion management (HDMM) camera system for patient tracking during treatment. We report on the first patient with meningioma at the left petrous bone treated with adaptive fractionated stereotactic radiotherapy (a-gkFSRT). The first patient treated with Gamma Knife Icon at our institute received MR imaging for preplanning before treatment. For each treatment fraction, a daily CBCT was performed to verify the actual scull/tumor position. The system automatically adapted the planned shot positions to the daily position and recalculated the dose distribution (online adaptive planning). During treatment, the HDMM system recorded the intrafractional patient motion. Furthermore, the required times were recorded to define a clinical treatment slot. Total treatment time was around 20 min. Patient positioning needed 0.8 min, CBCT positioning plus acquisition 1.65 min, CT data processing and adaptive planning 2.66 min, and treatment 15.6 min. The differences for the five daily CBCTs compared to the reference are for rotation: -0.59 ± 0.49°/0.18 ± 0.20°/0.05 ± 0.36° and for translation: 0.94 ± 0.52 mm/-0.08 ± 0.08 mm/-1.13 ± 0.89 mm. Over all fractions, an intrafractional movement of 0.13 ± 0.04 mm was observed. The Gamma Knife Icon allows combining the accuracy of the stereotactic Gamma Knife system with the flexibility of fractionated treatment with the mask system and CBCT. Furthermore, the Icon system introduces a new online patient tracking system to the clinical routine. The interfractional accuracy of patient positioning was controlled with a thermoplastic mask and CBCT.

  17. Gamma knife radiosurgery for glomus jugulare tumors: therapeutic advantages of minimalism in the skull base.

    PubMed

    Sharma, Manish S; Gupta, A; Kale, S S; Agrawal, D; Mahapatra, A K; Sharma, B S

    2008-01-01

    Glomus jugulare (GJ) tumors are paragangliomas found in the region of the jugular foramen. Surgery with/without embolization and conventional radiotherapy has been the traditional management option. To analyze the efficacy of gamma knife radiosurgery (GKS) as a primary or an adjunctive form of therapy. A retrospective analysis of patients who received GKS at a tertiary neurosurgical center was performed. Of the 1601 patients who underwent GKS from 1997 to 2006, 24 patients with GJ underwent 25 procedures. The average age of the cohort was 46.6 years (range, 22-76 years) and the male to female ratio was 1:2. The most common neurological deficit was IX, X, XI cranial nerve paresis (15/24). Fifteen patients received primary GKS. Mean tumor size was 8.7 cc (range 1.1-17.2 cc). The coverage achieved was 93.1% (range 90-97%) using a mean tumor margin dose of 16.4 Gy (range 12-25 Gy) at a mean isodose of 49.5% (range 45-50%). Thirteen patients (six primary and seven secondary) were available for follow-up at a median interval of 24 months (range seven to 48 months). The average tumor size was 7.9 cc (range 1.1-17.2 cc). Using a mean tumor margin dose of 16.3 Gy (range 12-20 Gy) 93.6% coverage (range 91-97%) was achieved. Six patients improved clinically. A single patient developed transient trigeminal neuralgia. Magnetic resonance imaging follow-up was available for 10 patients; seven recorded a decrease in size. There was no tumor progression. Gamma knife radiosurgery is a safe and effective primary and secondary modality of treatment for GJ.

  18. Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

    PubMed

    Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibić, Juraj; Heinrich, Zdravko

    2014-12-01

    Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  19. Recurrent Juvenile Nasopharyngeal Angiofibroma Treated with Gamma Knife Surgery

    PubMed Central

    Park, Chul-Kee; Paek, Sun Ha; Chung, Hyun-Tai; Jung, Hee-Won

    2006-01-01

    Radiosurgery has been rarely applied for juvenile nasopharyngeal angiofibroma (JNA) and cumulative reports are lacking. The authors report a case of successful treatment of recurred JNA with gamma knife surgery (GKS). A 48-yr-old man was presented with right visual acuity deterioration and brain magnetic resonance images (MRI) disclosed a 3 cm-sized intraorbital mass in the right orbit. He underwent a right fronto-temporal craniotomy and the mass was subtotally removed to preserve visual function. Histological diagnosis confirmed JNA in typical nature. However, the vision gradually worsened to fail four years after operation. MRI then showed regrowth of the tumor occupying most of the right orbit. GKS was done for the recurred lesion. A dose of 17 Gy was delivered to the 50% isodose line of tumor margin. During the following four-year follow-up period, the mass disappeared almost completely without any complications. Usually JNA can be exclusively diagnosed by radiological study alone. So this report of successful treatment of JNA with GKS may provide an important clue for the novel indication of GKS. PMID:16891831

  20. Investigation of intracranial peripheral dose arising from the treatment of large lesions with Leksell GammaKnife Perfexion.

    PubMed

    Ruschin, Mark; Nordström, Håkan; Kjäll, Per; Cho, Young-Bin; Jaffray, David

    2009-06-01

    This investigation involves quantifying the extent of intracranial peripheral dose arising from simulated targets situated in the skull-base or upper-spine region using the Leksell GammaKnife Perfexion treatment unit. For each of three spherical target volumes--denoted as Vs (4 cm3), VM (18 cm3), and VL (60 cm3)--three treatment plans were manually generated, one for each of the three collimator sizes--4, 8, and 16 mm. Each of the plans was delivered to a spherical dosimetry phantom with an insert containing EBT Gafchromic film. The total dose at 70 mm from the targets' edges, %D(70 mm), was measured as a function of elevation angle and expressed as a percentage of the prescription dose. The film insert was placed centered in the median sagittal plane (Leksell X = 100) and %D(70 mm) was measured for the angular range from 0 degree (superior/along Z axis) to 90 degrees (anterior/along Y axis). For a given collimator i, the irradiation time ti to treat a spherical target of volume V using the 50% isodose line was observed to follow a power-law relationship of the form ti = Ai(V/ Vi)n where Ai was the maximum dose divided by collimator dose rate and Vi was the volume encompassed by the 50% isodose line for a single shot. The mean value of n was 0.61 (range: 0.61-0.62). Along the superior (Z) direction (angle=0 degree) and up to angles of around 30 degrees, the %D(70 mm) was always highest for the 4 mm plans, followed by the 8 mm, followed by the 16 mm. In this angular range, the maximum measured %D(70 mm) was 1.7% of the prescription dose. The intracranial peripheral dose along the superior direction (combined scatter and leakage dose) resulting from irradiation of upper-spine or base-of-skull lesions is measured to be less than 2% of the prescription dose, even for very large (60 cm3) targets. The results of this study indicate that, for a given target volume, treatment plans consisting of only 4 mm shots yield larger peripheral dose in the superior direction than 8

  1. A new Gamma Knife radiosurgery paradigm: Tomosurgery

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoliang

    The Leksell (Elekta, Stockholm, Sweden) Gamma Knife(TM) (LGK) is the worldwide standard-of-care for the radiosurgical treatment of a wide variety of intracranial lesions. The current LGK utilizes a step-and-shoot dose delivery mechanism where the centroid of each conformal radiation dose (i.e., the shot isocenter) requires repositioning the patient outside of the irradiation field. Perhaps the greatest challenge the LGK treatment team faces is planning the treatment of large and/or complexly shaped lesions that may be in close proximity to critical neural or vascular structures. The standard manual treatment planning approach is a time consuming procedure where additional time spent does not guarantee the identification of an increasingly optimal treatment plan. I propose a new radiosurgery paradigm which I refer to as "Tomosurgery". The Tomosurgery paradigm begins with the division of the target volume into a series of adjacent treatment slices, each with a carefully determined optimal thickness. The use of a continuously moving disk-shaped radiation shot that moves through the lesion in a raster-scanning pattern is expected to improve overall radiation dose conformality and homogeneity. The Tomosurgery treatment planning algorithm recruits a two-stage optimization strategy, which first plans each treatment slice as a simplified 2D problem and secondly optimally assembles the 2D treatment plans into the final 3D treatment plan. Tested on 11 clinical LGK cases, the automated inversely-generated Tomosurgery treatment plans performed as well or better than the neurosurgeon's manually created treatment plans across all criteria: (a) dose volume histograms, (b) dose homogeneity, (c) dose conformality, and (d) critical structure damage, where applicable. LGK Tomosurgery inverse treatment planning required much less time than standard of care, manual (i.e., forward) LGK treatment planning procedures. These results suggest that Tomosurgery might provide an improvement

  2. TH-AB-201-01: A Feasibility Study of Independent Dose Verification for CyberKnife

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sato, A; Noda, T; Keduka, Y

    2016-06-15

    Purpose: CyberKnife irradiation is composed of tiny-size, multiple and intensity-modulated beams compared to conventional linacs. Few of the publications for Independent dose calculation verification for CyberKnife have been reported. In this study, we evaluated the feasibility of independent dose verification for CyberKnife treatment as Secondary check. Methods: The followings were measured: test plans using some static and single beams, clinical plans in a phantom and using patient’s CT. 75 patient plans were collected from several treatment sites of brain, lung, liver and bone. In the test plans and the phantom plans, a pinpoint ion-chamber measurement was performed to assess dosemore » deviation for a treatment planning system (TPS) and an independent verification program of Simple MU Analysis (SMU). In the clinical plans, dose deviation between the SMU and the TPS was performed. Results: In test plan, the dose deviations were 3.3±4.5%, and 4.1±4.4% for the TPS and the SMU, respectively. In the phantom measurements for the clinical plans, the dose deviations were −0.2±3.6% for the TPS and −2.3±4.8% for the SMU. In the clinical plans using the patient’s CT, the dose deviations were −3.0±2.1% (Mean±1SD). The systematic difference was partially derived from inverse square law and penumbra calculation. Conclusion: The independent dose calculation for CyberKnife shows −3.0±4.2% (Mean±2SD) and our study, the confidence limit was achieved within 5% of the tolerance level from AAPM task group 114 for non-IMRT treatment. Thus, it may be feasible to use independent dose calculation verification for CyberKnife treatment as the secondary check. This research is partially supported by Japan Agency for Medical Research and Development (AMED)« less

  3. Long-term follow-up studies of Gamma Knife surgery for patients with neurofibromatosis Type 2.

    PubMed

    Sun, Shibin; Liu, Ali

    2014-12-01

    The aim of this study was to evaluate long-term clinical outcomes after Gamma Knife surgery (GKS) for patients with neurofibromatosis Type 2 (NF2) and the role of GKS in the management of NF2. From December 1994 through December 2008, a total of 46 patients (21 male, 25 female) with NF2 underwent GKS and follow-up evaluation for at least 5 years at the Gamma Knife Center of the Beijing Neurosurgical Institute. GKS was performed using the Leksell Gamma Knife Models B and C. The mean age of the patients was 30 years (range 13-59 years). A family history of NF2 was found for 9 (20%) patients. The NF2 phenotype was thought to be Wishart for 20 (44%) and Feiling-Gardner for 26 (56%) patients. Among these 46 patients, GKS was performed to treat 195 tumors (73 vestibular schwannomas and 122 other tumors including other schwannomas and meningiomas). For vestibular schwannomas, the mean volume was 5.1 cm(3) (median 3.6 cm(3), range 0.3-27.3 cm(3)), the mean margin dose was 12.9 Gy (range 10-14 Gy), and the mean maximum dose was 27.3 Gy (range 16.2-40 Gy). For other tumors, the mean volume was 1.7 cm(3) (range 0.3-5.5 cm(3)), the mean margin dose was 13.3 Gy (range 11-14 Gy), and the mean maximum dose was 26.0 Gy (range 18.0-30.4 Gy). The median duration of follow-up was 109 months (range 8-195 months). For the 73 vestibular schwannomas that underwent GKS, the latest follow-up MR images demonstrated regression of 30 (41%) tumors, stable size for 31 (43%) tumors, and enlargement of 12 (16%) tumors. The total rate of tumor control for bilateral vestibular schwannomas in patients with NF2 was 84%. Of the 122 other types of tumors that underwent GKS, 103 (85%) showed no tumor enlargement. The rate of serviceable hearing preservation after GKS was 31.9% (15/47). The actuarial rates for hearing preservation at 3 years, 5 years, 10 years, and 15 years were 98%, 93%, 44%, and 17%, respectively. Of the 46 patients, 22 (48%) became completely bilaterally deaf, 17 (37%) retained

  4. Cavernomas: Outcomes after gamma-knife radiosurgery in Iran

    PubMed Central

    Azimi, Parisa; Shahzadi, Sohrab; Bitaraf, Mohammad Ali; Azar, Maziar; Alikhani, Mazdak; Zali, Alireza; Sadeghi, Sohrab

    2015-01-01

    Background: Treatment of cavernomas remains a challenge in surgically inaccessible regions. The purpose of this study was to evaluate outcomes after gamma-knife surgery (GKS) for these patients. Materials and Methods: A retrospective review of 100 patients treated between 2003 and 2011 was conducted in order to evaluate hemorrhage rates, complications, radiation effects after GKS. Dosage at the tumor margin was stratified into two groups: those that received ≤13 Gy; and those who received >13 Gy. The demographic and clinical characteristics of patients including age, gender, and hemorrhage rates were extracted from care records. Results: The median age was 32.5 years (ranging from 15 to 79). 44% were female. The median follow-up time was 42.2 months (ranging from 24 to 90). The median volume of the lesions was 1050.0 mm3 (ranging from 112.0 to 4100.0) before GKS. A reduction of 27.5% in median size of cavernomas was achieved at the last follow-up. There was 12% treatment-related morbidity after GKS. The hemorrhage rate in the first 2 years after GKS was 4.1% and 1.9% thereafter. There was no mortality due to GKS, and 93 patients were alive at the last follow-up. The radiation-related complication developed with marginal dose 13 Gy. Conclusion: The GKS for cavernomas appears to be a safe and beneficial in carefully selected patients. Low-dose GKS may be effective for the management of cavernous malformations. PMID:25767582

  5. OUT-OF-FIELD DOSES IN CHILDREN TREATED FOR LARGE ARTERIOVENOUS MALFORMATIONS USING HYPOFRACTIONATED GAMMA KNIFE RADIOSURGERY AND INTENSITY-MODULATED RADIATION THERAPY.

    PubMed

    De Saint-Hubert, Marijke; Majer, Marija; Hršak, Hrvoje; Heinrich, Zdravko; Kneževic, Željka; Miljanic, Saveta; Porwol, Paulina; Stolarczyk, Liliana; Vanhavere, Filip; Harrison, Roger M

    2018-01-17

    The purpose of this study was to measure out-of-field organ doses in two anthropomorphic child phantoms for the treatment of large brain arteriovenous malformations (AVMs) using hypofractionated gamma knife (GK) radiosurgery and to compare these with an alternative treatment using intensity-modulated radiation therapy (IMRT). Target volume was identical in size and shape in all cases. Radiophotoluminescent (RPL), thermoluminescent (TL) and optically stimulated luminescent (OSL) dosimeters were used for out-of-field dosimetry during GK treatment and a good agreement within 1-2% between results was shown. In addition, the use of multiple dosimetry systems strengthens the reliability of the findings. The number of GK isocentres was confirmed to be important for the magnitude of out-of-field doses. Measured GK doses for the same distance from the target, when expressed per target dose and isocentre, were comparable in both phantoms. GK out-of-field doses averaged for both phantoms were evaluated to be 120 mGy/Gy for eyes then sharply reduced to 20 mGy/Gy for mandible and slowly reduced up to 0.8 mGy/Gy for testes. Taking into account the fractionation regimen used to treat AVM patients, the total treatment organ doses to the out-of-field organs were calculated and compared with IMRT. The eyes were better spared with GK whilst for more distant organs doses were up to a factor of 2.8 and 4 times larger for GK compared to IMRT in 5-year and 10-year old phantoms, respectively. Presented out-of-field dose values are specific for the investigated AVM case, phantoms and treatment plans used for GK and IMRT, but provide useful information about out-of-field dose levels and emphasise their importance. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. SU-E-T-517: Investigation of Factors Contributing to Extracranial Radiation Doses From Leksell Gamma Knife

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kon, D; Kameda Medical Centre, Chiba, JP; Nakano, M

    2015-06-15

    Purpose The purpose of this study is to investigate dominant factors for doses to extracranial sites in treatment with Leksell Gamma Knife (LGK). Methods Monte Carlo simulation was implemented using EGS5 version 1.4.401. The simulation was divided into two major steps for the purpose of efficiency. As the first step, phase-space files were obtained at a scoring plane located just below patient-side surface of the collimator helmet of LGK. Scored particles were classified into three groups, primary, leakage and scatter, using their history information until their arrival to the scoring plane. Then classification was used at the following second stepmore » simulation to investigate which type of particle is dominant in the deposited energy at extra-cranial sites. In the second stage, a cylindrical phantom with a semisphere shaped head was modeled such that the geometrical center of the phantom’s head corresponds to the unit center point (UCP) of LGK. Scoring regions were arranged at 10 cm intervals from the UCP to 70 cm away on the central axis of the phantom. Energy deposition from each type of particles and location of interaction were recorded. Results The dominant factor of deposited energy depended on the collimator size. In the case of smaller collimator size, leakage was dominant. However, contribution of leakage was relatively small in the case of larger collimator size. The contribution of internal scatter varied with the distance from the UCP. In the proximal areas, internal scatter was dominant, whereas in the distal areas, particles interacting with machine components became dominant factor. Conclusion The Result of this study indicates that the dominant factor to dose to an extracranial site can vary with the distance from UCP and with collimator size. This means that the variation of this contribution must be considered for modeling of the extracranial dose especially in the distal area. This work was partly supported by the JSPS Core

  7. Gamma knife radiosurgery for typical trigeminal neuralgia: An institutional review of 108 patients

    PubMed Central

    Elaimy, Ameer L.; Lamm, Andrew F.; Demakas, John J.; Mackay, Alexander R.; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Pfeffer, Robert D.; Cooke, Barton S.; Peressini, Benjamin J.; Lee, Christopher M.

    2013-01-01

    Background: In this study, we present the previously unreported pain relief outcomes of 108 patients treated at Gamma Knife of Spokane for typical trigeminal neuralgia (TN) between 2002 and 2011. Methods: Pain relief outcomes were measured using the Barrow Neurological Institute (BNI) pain intensity scale. In addition, the effects gender, age at treatment, pain laterality, previous surgical treatment, repeat Gamma Knife radiosurgery (GKRS), and maximum radiosurgery dose have on patient pain relief outcomes were retrospectively analyzed. Statistical analysis was performed using Andersen 95% confidence intervals, approximate confidence intervals for log hazard ratios, and multivariate Cox proportional hazard models. Results: All 108 patients included in this study were grouped into BNI class IV or V prior to GKRS. The median clinical follow-up time was determined to be 15 months. Following the first GKRS procedure, 71% of patients were grouped into BNI class I-IIIb (I = 31%; II = 3%; IIIa = 19%; IIIb = 18%) and the median duration of pain relief for those patients was determined to be 11.8 months. New facial numbness was reported in 19% of patients and new facial paresthesias were reported in 7% of patients after the first GKRS procedure. A total of 19 repeat procedures were performed on the 108 patients included in this study. Following the second GKRS procedure, 73% of patients were grouped into BNI class I-IIIb (I = 44%; II = 6%; IIIa = 17%, IIIb = 6%) and the median duration of pain relief for those patients was determined to be 4.9 months. For repeat procedures, new facial numbness was reported in 22% of patients and new facial paresthesias were reported in 6% of patients. Conclusions: GKRS is a safe and effective management approach for patients diagnosed with typical TN. However, further studies and supporting research is needed on the effects previous surgical treatment, number of radiosurgery procedures, and maximum radiosurgery dose have on GKRS clinical

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bisht, R; Kale, S; Gopishankar, N

    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 headmore » 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

  9. 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

  10. Quality assurance for gamma knives

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    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,more » 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.« less

  11. Gamma Knife radiosurgery for intracranial meningiomas: Do we need to treat the dural tail? A single-center retrospective analysis and an overview of the literature.

    PubMed

    Bulthuis, Vincent J; Hanssens, Patrick E J; Lie, Suan Te; van Overbeeke, Jacobus J

    2014-01-01

    The dural tail (DT) has been described as a common feature in meningiomas. There is a great variation of tumor invasion and extent of tumor cells in the DT. Therefore, the necessity to include the whole DT in Gamma Knife radiosurgery is not clear, since inclusion increases the target volume and therefore increases the risk of complications. In this analysis, we evaluated whether the complete tail should be included as part of the target in Gamma Knife radiosurgery for meningiomas. Between June 2002 and December 2010, Gamma Knife radiosurgery was performed in 160 patients with 203 meningiomas with a DT. In 105 tumors, the diagnosis was based on magnetic resonance imaging (MRI) characteristics, and in 98 tumors, the diagnosis was confirmed by histopathologic examination after surgery. The median volume of the tumors was 3.55 cc. All tumors were treated with Gamma Knife radiosurgery with a median prescribed dose of 13 Gy (range 11-15), resulting in a median marginal dose of 11 Gy (range 10-15). Only the part of the DT closely related to the tumor mass was included in the target. The median follow-up period was 41 months (range 12-123). In image-based meningiomas, the overall local control rate was 96.2% with 2- and 5-year control rates of 98.0% and 95.1%, respectively. In WHO grade I tumors, the overall local control rate was 85.9% with 2- and 5-year control rates of 94.5% and 88.0%, respectively. The overall local control rate in World Health Organization (WHO) grade II tumors was 70.6% with control rates of 83.4% and 64.4% after 2 and 5 years, respectively. The growth of all new tumors was found in the radiation target area. No tumor growth was observed in the part of the DT that had been excluded from the target volume. We found in this study that routinely excluding the DT from the target does not lead to out-of-field tumor progression. Given the possibility that the DT is infiltrated with tumor cells, regular follow-up is needed.

  12. A new Gamma Knife registered radiosurgery paradigm: Tomosurgery

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hu, X.; Maciunas, R. J.; Dean, D.

    This study proposes and simulates an inverse treatment planning and a continuous dose delivery approach for the Leksell Gamma Knife registered (LGK, Elekta, Stockholm, Sweden) which we refer to as 'Tomosurgery'. Tomosurgery uses an isocenter that moves within the irradiation field to continuously deliver the prescribed radiation dose in a raster-scanning format, slice by slice, within an intracranial lesion. Our Tomosurgery automated (inverse) treatment planning algorithm utilizes a two-stage optimization strategy. The first stage reduces the current three-dimensional (3D) treatment planning problem to a series of more easily solved 2D treatment planning subproblems. In the second stage, those 2D treatmentmore » plans are assembled to obtain a final 3D treatment plan for the entire lesion. We created Tomosurgery treatment plans for 11 patients who had already received manually-generated LGK treatment plans to treat brain tumors. For the seven cases without critical structures (CS), the Tomosurgery treatment plans showed borderline to significant improvement in within-tumor dose standard deviation (STD) (p<0.058, or p<0.011 excluding case 2) and conformality (p<0.042), respectively. In three of the four cases that presented CS, the Tomosurgery treatment plans showed no statistically significant improvements in dose conformality (p<0.184), and borderline significance in improving within-tumor dose homogeneity (p<0.054); CS damage measured by V{sub 20} or V{sub 30} (i.e., irradiated CS volume that receives {>=}20% or {>=}30% of the maximum dose) showed no significant improvement in the Tomosurgery treatment plans (p<0.345 and p<0.423, respectively). However, the overall CS dose volume histograms were improved in the Tomosurgery treatment plans. In addition, the LGK Tomosurgery inverse treatment planning required less time than standard of care, forward (manual) LGK treatment planning (i.e., 5-35 min vs 1-3 h) for all 11 cases. We expect that LGK Tomosurgery will

  13. Implementation of Monte Carlo Dose calculation for CyberKnife treatment planning

    NASA Astrophysics Data System (ADS)

    Ma, C.-M.; Li, J. S.; Deng, J.; Fan, J.

    2008-02-01

    Accurate dose calculation is essential to advanced stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) especially for treatment planning involving heterogeneous patient anatomy. This paper describes the implementation of a fast Monte Carlo dose calculation algorithm in SRS/SRT treatment planning for the CyberKnife® SRS/SRT system. A superposition Monte Carlo algorithm is developed for this application. Photon mean free paths and interaction types for different materials and energies as well as the tracks of secondary electrons are pre-simulated using the MCSIM system. Photon interaction forcing and splitting are applied to the source photons in the patient calculation and the pre-simulated electron tracks are repeated with proper corrections based on the tissue density and electron stopping powers. Electron energy is deposited along the tracks and accumulated in the simulation geometry. Scattered and bremsstrahlung photons are transported, after applying the Russian roulette technique, in the same way as the primary photons. Dose calculations are compared with full Monte Carlo simulations performed using EGS4/MCSIM and the CyberKnife treatment planning system (TPS) for lung, head & neck and liver treatments. Comparisons with full Monte Carlo simulations show excellent agreement (within 0.5%). More than 10% differences in the target dose are found between Monte Carlo simulations and the CyberKnife TPS for SRS/SRT lung treatment while negligible differences are shown in head and neck and liver for the cases investigated. The calculation time using our superposition Monte Carlo algorithm is reduced up to 62 times (46 times on average for 10 typical clinical cases) compared to full Monte Carlo simulations. SRS/SRT dose distributions calculated by simple dose algorithms may be significantly overestimated for small lung target volumes, which can be improved by accurate Monte Carlo dose calculations.

  14. Brain metastases in women with epithelial ovarian cancer: multimodal treatment including surgery or gamma-knife radiation is associated with prolonged survival.

    PubMed

    Niu, Xiaoyu; Rajanbabu, Anupama; Delisle, Megan; Peng, Feng; Vijaykumar, Dehannathuparambil K; Pavithran, Keechilattu; Feng, Yukuan; Lau, Susie; Gotlieb, Walter H; Press, Joshua Z

    2013-09-01

    To explore the impact of treatment modality on survival in patients with brain metastases from epithelial ovarian cancer. We conducted a retrospective review of cases of ovarian cancer with brain metastases treated at institutions in three countries (Canada, China, and India) and conducted a search for studies regarding brain metastases in ovarian cancer reporting survival related to treatment modality. Survival was analyzed according to treatment regimens involving (1) some form of surgical excision or gamma-knife radiation with or without other modalities, (2) other modalities without surgery or gamma-knife radiation, or (3) palliation only. Twelve patients (mean age 56 years) with detailed treatment/outcome data were included; five were from China, four from Canada, and three from India. Median time from diagnosis of ovarian cancer to brain metastasis was 19 months (range 10 to 37 months), and overall median survival time from diagnosis of ovarian cancer was 38 months (13 to 82 months). Median survival time from diagnosis of brain metastasis was 17 months (1 to 45 months). Among patients who had multimodal treatment including gamma-knife radiotherapy or surgical excision, the median survival time after the identification of brain metastasis was 25.6 months, compared with 6.0 months in patients whose treatment did not include this type of focused localized modality (P = 0.006). Analysis of 20 studies also indicated that use of gamma-knife radiotherapy and excisional surgery in multi-modal treatment resulted in improved median survival interval (25 months vs. 6.0 months, P < 0.001). In the subset of patients with brain metastases from ovarian cancer, prolonged survival may result from use of multidisciplinary therapy, particularly if metastases are amenable to localized treatments such as gamma-knife radiotherapy and surgical excision.

  15. Tumour regression of uveal melanoma after ruthenium-106 brachytherapy or stereotactic radiotherapy with gamma knife or linear accelerator.

    PubMed

    Georgopoulos, Michael; Zehetmayer, Martin; Ruhswurm, Irene; Toma-Bstaendig, Sabine; Ségur-Eltz, Nikolaus; Sacu, Stefan; Menapace, Rupert

    2003-01-01

    This study assesses differences in relative tumour regression and internal acoustic reflectivity after 3 methods of radiotherapy for uveal melanoma: (1) brachytherapy with ruthenium-106 radioactive plaques (RU), (2) fractionated high-dose gamma knife stereotactic irradiation in 2-3 fractions (GK) or (3) fractionated linear-accelerator-based stereotactic teletherapy in 5 fractions (Linac). Ultrasound measurements of tumour thickness and internal reflectivity were performed with standardised A scan pre-operatively and 3, 6, 9, 12, 18, 24 and 36 months postoperatively. Of 211 patients included in the study, 111 had a complete 3-year follow-up (RU: 41, GK: 37, Linac: 33). Differences in tumour thickness and internal reflectivity were assessed with analysis of variance, and post hoc multiple comparisons were calculated with Tukey's honestly significant difference test. Local tumour control was excellent with all 3 methods (>93%). At 36 months, relative tumour height reduction was 69, 50 and 30% after RU, GK and Linac, respectively. In all 3 treatment groups, internal reflectivity increased from about 30% initially to 60-70% 3 years after treatment. Brachytherapy with ruthenium-106 plaques results in a faster tumour regression as compared to teletherapy with gamma knife or Linac. Internal reflectivity increases comparably in all 3 groups. Besides tumour growth arrest, increasing internal reflectivity is considered as an important factor indicating successful treatment. Copyright 2003 S. Karger AG, Basel

  16. Gamma Knife surgery for intracranial chordoma and chondrosarcoma: radiosurgical perspectives and treatment outcomes.

    PubMed

    Kim, Ji Hee; Jung, Hyun Ho; Chang, Jong Hee; Chang, Jin Woo; Park, Yong Gou; Chang, Won Seok

    2014-12-01

    Intracranial chordomas and chondrosarcomas are histologically low-grade, locally invasive tumors that are reported to be similar in terms of anatomical location, clinical presentation, and radiological findings but different in terms of behavior and outcomes. The purpose of this study was to investigate and compare clinical outcomes after Gamma Knife surgery (GKS) for the treatment of intracranial chordoma and chondrosarcoma. The authors conducted a retrospective review of the results of radiosurgical treatment of intracranial chordomas and chondrosarcomas. They enrolled patients who had undergone GKS for intracranial chordoma or chondrosarcoma at the Yonsei Gamma Knife Center, Yonsei University College of Medicine, from October 2000 through June 2007. Analyses included only patients for whom the disease was pathologically diagnosed before GKS and for whom more than 5 years of follow-up data after GKS were available. Rates of progression-free survival and overall survival were analyzed and compared according to tumor pathology. Moreover, the association between tumor control and the margin radiation dose to the tumor was analyzed, and the rate of tumor volume change after GKS was quantified. A total of 10 patients were enrolled in this study. Of these, 5 patients underwent a total of 8 sessions of GKS for chordoma, and the other 5 patients underwent a total of 7 sessions of GKS for chondrosarcoma. The 2- and 5-year progression-free survival rates for patients in the chordoma group were 70% and 35%, respectively, and rates for patients in the chondrosarcoma group were 100% and 80%, respectively (log-rank test, p = 0.04). The 2- and 5-year overall survival rates after GKS for patients in the chordoma group were 87.5% and 72.9%, respectively, and rates for patients in the chondrosarcoma group were 100% and 100%, respectively (log-rank test, p = 0.03). The mean rates of tumor volume change 2 years after radiosurgery were 79.64% and 39.91% for chordoma and

  17. Radiological aspects of gamma knife radiosurgery for arteriovenous malformations and other non-tumoural disorders of the brain.

    PubMed

    Guo, W Y

    1993-01-01

    The aims of the thesis were to investigate stereotaxic procedures in radiosurgery for cerebral arteriovenous malformations (AVMs) and radiation effects of single session high-dose irradiation delivered by gamma knife on the human brain. Investigation of gamma knife radiosurgery in 1,464 patients constitutes the data base of this thesis. High quality stereotaxic angiography is the gold standard targeting imaging in radiosurgery for cerebral AVMs, particularly for small AVMs or residual AVMs after other treatments. For medium and large size AVMs, stereotaxic MR techniques can improve targeting precision and decrease irradiation volume as compared to stereotaxic angiography in selected cases provided that proper pulse sequences are used. Combined treatments, where embolization precedes radiosurgery, can improve amenability of the treatment for large AVMs. This is on condition that the partially embolized nidi are well delineated and the volume of the residual nidi has been decreased to a level where an optimum irradiation can be safely prescribed. Radiologically, adverse radiation effects (ARE) of gamma knife radiosurgery for cerebral AVMs are observed in 16% (131/816) of the patients. The ARE are observed as a focal low attenuation on CT or as a focal high signal on MR image without enhancement in 47% (61/131), and as a peripheral or homogeneous enhancing lesion in 48% (63/131). MR imaging is more sensitive than CT in detecting the ARE. 91% of the ARE are observed within 18 months after radiosurgery and 89% are seen to regress within 18 months. Clinically, symptomatic ARE are only observed in 6% (51/816) and only in half of them, i.e. 3%, are the symptoms permanent. The risk of ARE in radiosurgery for venous angiomas is higher as compared to AVMs. Other mechanisms have probably been employed. In gamma capsulotomy, the necrotic lesions and reaction volumes created by using multiple isocentres of 4 mm collimators are less predictable as compared to that by single

  18. Long-term effectiveness and safety of stereotactic gamma knife surgery as a primary sole treatment in the management of glomus jagulare tumor.

    PubMed

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

    2018-05-01

    This study aims to report and confirm long-term effectiveness and safety of stereotactic Gamma Knife Surgery as a primary sole treatment in the management of 40 glomus jagulare tumors patients. Retrospective analysis of clinical and radiological outcomes of 40 GJTs consecutive patients treated with GKS as primary sole treatment at International Medical Center (IMC), Cairo-Egypt from the beginning of 2005 till the end of 2014,with mean follow-up period of 84 months (range 36-156 months), mean tumor volume was 6.5 cc, and mean peripheral radiation dose of 15 Gy, to mean isodose curve of 38%. The most common neurological deficit at initial evaluation was bulbar symptoms in 24 patients, followed by pulsatile tinnitus in 22, deterioration of hearing in 20 patients. The overall clinical control achieved in 92.5% of patients, while actuarial tumor size control rate post- GKS was 97.5% at 3 years, 97% at 5 years and 92% at 10 years of follow-up period. Gamma knife surgery could be used effectively and safely as a primary sole treatment tool in the management of glomus jugulare tumors. Copyright © 2018 Elsevier B.V. All rights reserved.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Massager, Nicolas; Nissim, Ouzi; Murata, Noriko

    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 patientsmore » 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.« less

  20. Clinical efficacy of gamma knife and surgery treatment of mesial temporal lobe epilepsy and their effects on EF-Tumt and EF-Tsmt expression.

    PubMed

    Wang, X-Q; Zhang, X-D; Han, Y-M; Shi, X-F; Lan, Z-B; Men, X-X; Pan, Y-W

    2017-04-01

    To study the clinical efficacy of gamma knife and surgery treatment of mesial temporal lobe epilepsy (MTLE) and their effects on EF-Tumt and EF-Tsmt expression. The data of 78 cases of MTLE patients treated in our hospital from April 2011 to March 2013 were retrospectively analyzed. The patients were divided into two groups according to the treatment methods: the surgery group (including 41 cases) and the gamma knife group (including 37 cases). The clinical efficacy, the occurrence and recurrence of complications were evaluated, respectively; meanwhile, the expression of the EF-Tumt protein and EF-Tsmt protein in brain tissue were analyzed. The difference between the efficacy rate of the two groups showed no statistical significance (χ2=0.960, p>0.05). The complication rate of the gamma knife group was significantly lower than that of the control group (χ2=6.430, p<0.05). The recurrence rate of the patients in the gamma knife group was significantly lower than that of the patients in the surgery group (p>0.05). Within the two groups, the positive expression granum of EF-Tsmt protein and EF-Tumt protein of the two groups after treatment were significantly lower than that before treatment (p<0.05). After treatment, the positive expression granum of EF-Tsmt protein of the patients in the gamma knife group was obviously more than that of the patients in the surgery group (p<0.05). The difference between the positive expression granum of EF-Tumt protein of the two groups showed no statistical significance (p>0.05). Before and after treatment within the group, the positive cell of EF-Tsmt protein and EF-Tumt protein of the two groups of patients after treatment were significantly lower than that before treatment (p<0.05). After treatment, the difference between the EF-Tsmt protein positive cell and the EF-Tumt protein positive cell of the two groups of patients showed no statistical significance (p>0.05). Both surgery and gamma knife could treat MTLE effectively, and

  1. Real-time inverse planning for Gamma Knife radiosurgery.

    PubMed

    Wu, Q Jackie; Chankong, Vira; Jitprapaikulsarn, Suradet; Wessels, Barry W; Einstein, Douglas B; Mathayomchan, Boonyanit; Kinsella, Timothy J

    2003-11-01

    The challenges of real-time Gamma Knife inverse planning are the large number of variables involved and the unknown search space a priori. With limited collimator sizes, shots have to be heavily overlapped to form a smooth prescription isodose line that conforms to the irregular target shape. Such overlaps greatly influence the total number of shots per plan, making pre-determination of the total number of shots impractical. However, this total number of shots usually defines the search space, a pre-requisite for most of the optimization methods. Since each shot only covers part of the target, a collection of shots in different locations and various collimator sizes selected makes up the global dose distribution that conforms to the target. Hence, planning or placing these shots is a combinatorial optimization process that is computationally expensive by nature. We have previously developed a theory of shot placement and optimization based on skeletonization. The real-time inverse planning process, reported in this paper, is an expansion and the clinical implementation of this theory. The complete planning process consists of two steps. The first step is to determine an optimal number of shots including locations and sizes and to assign initial collimator size to each of the shots. The second step is to fine-tune the weights using a linear-programming technique. The objective function is to minimize the total dose to the target boundary (i.e., maximize the dose conformity). Results of an ellipsoid test target and ten clinical cases are presented. The clinical cases are also compared with physician's manual plans. The target coverage is more than 99% for manual plans and 97% for all the inverse plans. The RTOG PITV conformity indices for the manual plans are between 1.16 and 3.46, compared to 1.36 to 2.4 for the inverse plans. All the inverse plans are generated in less than 2 min, making real-time inverse planning a reality.

  2. TH-CD-BRA-09: Towards Absolute Dose Measurement in MRI-Linac and Gamma-Knife: Design and Construction of An MR-Compatible Water Calorimeter

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Entezari, N; Sarfehnia, A; Renaud, J

    Purpose: The purpose of this work is to design and optimize a portable Water Calorimeter (WC) for use in a commercial MRI-linac and Gamma-knife in addition to conventional radiotherapy linacs. Water calorimeters determine absorbed dose to water at a point by measuring radiation-induced temperature rise of the volume (the two are related by the medium specific heat capacity). In this formalism, one important correction factor is heat transfer correction k-ht. It compensates for heat gain/loss due to conductive and convective effects, and is numerically calculated as ratio of temperature rise in the absence of heat loss to that in themore » presence of heat loss. Operating at 4°C ensures convection is minimal. Methods: A commercial finite element software was used to evaluate several WC designs with different insulation materials and thicknesses; channels allowing coolant to travel around WC (to sustain WC at 4°C) were modeled, and worst-case scenario variation in the temperature of the coolant was simulated for optimization purposes (2.6 mK/s). Additionally, several calorimeter vessel design parameters (front/back glass thickness/separation, diameter) were also simulated and optimized. Optimization is based on minimizing long term calorimeter drift (24h) as well as variation and magnitude of k-ht. Results: The final selected WC design reached a modest drift of 11µK/s after 15h for the worst-case coolant temperature variation. This design consists of coolant channels being encompassed on both sides by cryogel insulation. For the MRI-linac beam, glass thickness plays the largest effect on k-ht with variation of upto 0.6% in the first run for thicknesses ranging between 0.5–1.7mm. Subsequent runs vary only within 0.1% with glass thickness. Other factors such as vessel radius and top/bottom glass separation have sub 0.1% effects on k-ht. Conclusion: An MR-safe 4°C stagnant WC appropriate for dosimetry in MRI-linac and Gamma-Knife was designed, optimized, and

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Han, Jung Ho; Kim, Dong Gyu; Chung, Hyun-Tai

    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 tumormore » 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.« less

  4. Brain metastases in cancer patients attending a Gamma Knife Center: A study from a single institute in Iran

    PubMed Central

    Azimi, Parisa; Shahzadi, Sohrab; Bitaraf, Mohammad Ali; Azar, Maziar; Alikhani, Mazdak; Zali, Alireza; Sadeghi, Sohrab; Montazeri, Ali

    2017-01-01

    Background: This study was aimed to explore data on brain metastases in cancer patients attending the Iranian Gamma Knife Center. Meterials and Methods: This was a retrospective study. In all 5216 case records of patients who referred to the Iranian Gamma Knife Center for treatment of brain tumors during year 2003-2011 were reviewed. Data were explored to identify patients who developed brain metastases due to cancer and assessed the information as applied to cancer patients including survival analysis. Results: Two hundred and twenty patients were identified as having brain metastases due to cancer. The mean age of patients was 54.0 (standard deviation [SD] =12.7) years. Patients were followed for an average of 7 months after treatment with gamma-knife. The median survival time for different the Graded Prognostic Assessment (GPA) was: GPA: 0-1, 4.0 ± 0.4 months; GPA: 1.5-2.5, 6.0 ± 0.7 months; GPA: 3, 9.0 ± 0.9 months; and GPA: 3.5-4.0, 12.0 ± 1.8 months and the overall median survival was 7.0 (SD = 0.6) months. Conclusion: The findings suggest that many cancer patients in Iran might develop brain metastasis. Although, this is not a very high incidence compared with the existing statistics from other countries, there is an urgent need to explore the issue further. PMID:28761536

  5. Brain metastases in cancer patients attending a Gamma Knife Center: A study from a single institute in Iran.

    PubMed

    Azimi, Parisa; Shahzadi, Sohrab; Bitaraf, Mohammad Ali; Azar, Maziar; Alikhani, Mazdak; Zali, Alireza; Sadeghi, Sohrab; Montazeri, Ali

    2017-01-01

    This study was aimed to explore data on brain metastases in cancer patients attending the Iranian Gamma Knife Center. This was a retrospective study. In all 5216 case records of patients who referred to the Iranian Gamma Knife Center for treatment of brain tumors during year 2003-2011 were reviewed. Data were explored to identify patients who developed brain metastases due to cancer and assessed the information as applied to cancer patients including survival analysis. Two hundred and twenty patients were identified as having brain metastases due to cancer. The mean age of patients was 54.0 (standard deviation [SD] =12.7) years. Patients were followed for an average of 7 months after treatment with gamma-knife. The median survival time for different the Graded Prognostic Assessment (GPA) was: GPA: 0-1, 4.0 ± 0.4 months; GPA: 1.5-2.5, 6.0 ± 0.7 months; GPA: 3, 9.0 ± 0.9 months; and GPA: 3.5-4.0, 12.0 ± 1.8 months and the overall median survival was 7.0 (SD = 0.6) months. The findings suggest that many cancer patients in Iran might develop brain metastasis. Although, this is not a very high incidence compared with the existing statistics from other countries, there is an urgent need to explore the issue further.

  6. Successful use of Gamma Knife surgery in a distal lenticulostriate artery aneurysm intervention.

    PubMed

    Lan, ZhiGang; Li, Jin; You, Chao; Chen, Jing

    2012-02-01

    We report a case of a 21-year-old woman who underwent radiosurgical treatment of a distal lenticulostriate artery (LSA) aneurysm. Twenty-two months after treatment, repeat angiography demonstrated patency of the parent vessel and complete obliteration of the aneurysm. Our case implies that Gamma Knife surgery (GKS) might serve as an alternative microinvasive technique in the treatment of LSA aneurysms, making this procedure a potential addition to present methods.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brezovich, Ivan A., E-mail: ibrezovich@uabmc.edu; Wu, Xingen; Duan, Jun

    2014-11-01

    in MRI- and CT-planned treatments were, respectively, −0.761 mm in the y-direction and 0.428 mm in the x-direction, well within safe limits. Conclusions: The highly accurate dose delivery was possible because the Gamma Knife, MRI scanner, and other equipment performed within tight limits and scans were acquired using the thinnest slices and smallest pixel sizes available. Had the individual devices performed only near the limits of their specifications, the cumulative error could have left parts of the trigeminal nerve undertreated. The presented end-to-end test gives assurance that patients had received the expected high quality treatment. End-to-end tests should become part of clinical practice.« less

  8. Gamma Knife Surgery for Metastatic Brain Tumors from Gynecologic Cancer.

    PubMed

    Matsunaga, Shigeo; Shuto, Takashi; Sato, Mitsuru

    2016-05-01

    The incidences of metastatic brain tumors from gynecologic cancer have increased. The results of Gamma Knife surgery (GKS) for the treatment of patients with brain metastases from gynecologic cancer (ovarian, endometrial, and uterine cervical cancers) were retrospectively analyzed to identify the efficacy and prognostic factors for local tumor control and survival. The medical records were retrospectively reviewed of 70 patients with 306 tumors who underwent GKS for brain metastases from gynecologic cancer between January 1995 and December 2013 in our institution. The primary cancers were ovarian in 33 patients with 147 tumors and uterine in 37 patients with 159 tumors. Median tumor volume was 0.3 cm(3). Median marginal prescription dose was 20 Gy. The local tumor control rates were 96.4% at 6 months and 89.9% at 1 year. There was no statistically significant difference between ovarian and uterine cancers. Higher prescription dose and smaller tumor volume were significantly correlated with local tumor control. Median overall survival time was 8 months. Primary ovarian cancer, controlled extracranial metastases, and solitary brain metastasis were significantly correlated with satisfactory overall survival. Median activities of daily living (ADL) preservation survival time was 8 months. Primary ovarian cancer, controlled extracranial metastases, and higher Karnofsky Performance Status score were significantly correlated with better ADL preservation. GKS is effective for control of tumor progression in patients with brain metastases from gynecologic cancer, and may provide neurologic benefits and preservation of the quality of life. Copyright © 2016 Elsevier Inc. All rights reserved.

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

    PubMed

    Régis, J; Bartolomei, F; de Toffol, B; Genton, P; Kobayashi, T; Mori, Y; Takakura, K; Hori, T; Inoue, H; Schröttner, O; Pendl, G; Wolf, A; Arita, K; Chauvel, P

    2000-12-01

    Drug-resistant epilepsy associated with hypothalamic hamartomas (HHs) can be cured by microsurgical resection of the lesions. Morbidity and mortality rates for microsurgery in this area are significant. Gamma knife surgery (GKS) is less invasive and seems to be well adapted for this indication. To evaluate the safety and efficacy of GKS to treat this uncommon pathological condition, we organized a multicenter retrospective study. Ten patients were treated in seven different centers. The follow-up periods were more than 12 months for eight patients, with a median follow-up period of 28 months (mean, 35 mo; range, 12-71 mo). All patients had severe drug-resistant epilepsy, including frequent gelastic and generalized tonic or tonicoclonic attacks. The median age was 13.5 years (range, 1-32 yr; mean, 14 yr) at the time of GKS. Three patients experienced precocious puberty. All patients had sessile HHs. The median marginal dose was 15.25 Gy (range, 12-20 Gy). Two patients were treated two times (at 19 and 49 mo) because of insufficient efficacy. All patients exhibited improvement. Four patients were seizure-free, one experienced rare nocturnal seizures, one experienced some rare partial seizures but no more generalized attacks, and two exhibited only improvement, with reductions in the frequency of seizures but persistence of some rare generalized seizures. Two patients, now seizure-free, were considered to exhibit insufficient improvement after the first GKS procedure and were treated a second time. A clear correlation between efficacy and dose was observed in this series. The marginal dose was more than 17 Gy for all patients in the successful group and less than 13 Gy for all patients in the "improved" group. No side effects were reported, except for poikilothermia in one patient. Behavior was clearly improved for two patients (with only slight improvements in their epilepsy). Complete coverage of the HHs did not seem to be mandatory, because the dosimetry spared a

  10. MRI textures as outcome predictor for Gamma Knife radiosurgery on vestibular schwannoma

    NASA Astrophysics Data System (ADS)

    Langenhuizen, P. P. J. H.; Legters, M. J. W.; Zinger, S.; Verheul, H. B.; Leenstra, S.; de With, P. H. N.

    2018-02-01

    Vestibular schwannomas (VS) are benign brain tumors that can be treated with high-precision focused radiation with the Gamma Knife in order to stop tumor growth. Outcome prediction of Gamma Knife radiosurgery (GKRS) treatment can help in determining whether GKRS will be effective on an individual patient basis. However, at present, prognostic factors of tumor control after GKRS for VS are largely unknown, and only clinical factors, such as size of the tumor at treatment and pre-treatment growth rate of the tumor, have been considered thus far. This research aims at outcome prediction of GKRS by means of quantitative texture feature analysis on conventional MRI scans. We compute first-order statistics and features based on gray-level co- occurrence (GLCM) and run-length matrices (RLM), and employ support vector machines and decision trees for classification. In a clinical dataset, consisting of 20 tumors showing treatment failure and 20 tumors exhibiting treatment success, we have discovered that the second-order statistical metrics distilled from GLCM and RLM are suitable for describing texture, but are slightly outperformed by simple first-order statistics, like mean, standard deviation and median. The obtained prediction accuracy is about 85%, but a final choice of the best feature can only be made after performing more extensive analyses on larger datasets. In any case, this work provides suitable texture measures for successful prediction of GKRS treatment outcome for VS.

  11. Benign orbital apex tumors treated with multisession gamma knife radiosurgery.

    PubMed

    Goh, Alice Siew Ching; Kim, Yoon-Duck; Woo, Kyung In; Lee, Jung-Il

    2013-03-01

    The orbital apex is an important anatomic landmark that hosts numerous critical neurovascular structures. Tumor resection performed at this complex region poses a therapeutic challenge to orbital surgeons and often is associated with significant visual morbidity. This article reports the efficacy and safety of multisession gamma knife radiosurgery (GKRS) in benign, well-circumscribed tumors located at the orbital apex. Retrospective interventional case series. Five patients with visual disturbances resulting from a benign, well-circumscribed orbital apex tumor (3 cases of cavernous hemangioma and 2 cases of schwannoma). Each patient treated with GKRS with a total radiation dose of 20 Gy in 4 sessions (5 Gy in each session with an isodose line of 50%) delivered to the tumor margin. Best-corrected visual acuity, visual field changes, orbital imaging, tumor growth control, and side effects of radiation. All patients demonstrated improvement in visual acuity, pupillary responses, color vision, and visual field. Tumor shrinkage was observed in all patients and remained stable until the last follow-up. No adverse events were noted during or after the radiosurgery. None of the patients experienced any radiation-related ocular morbidity. From this experience, multisession GKRS seems to be an effective management strategy to treat solitary, benign, well-circumscribed orbital apex tumors. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  12. Is it possible to avoid hypopituitarism after irradiation of pituitary adenomas by the Leksell gamma knife?

    PubMed

    Marek, Josef; Jezková, Jana; Hána, Václav; Krsek, Michal; Bandúrová, L'ubomíra; Pecen, Ladislav; Vladyka, Vilibald; Liscák, Roman

    2011-02-01

    Radiation therapy is one of the treatment options for pituitary adenomas. The most common side effect associated with Leksell gamma knife (LGK) irradiation is the development of hypopituitarism. The aim of this study was to verify that hypopituitarism does not develop if the maximum mean dose to pituitary is kept under 15 Gy and to evaluate the influence of maximum distal infundibulum dose on the development of hypopituitarism. We followed the incidence of hypopituitarism in 85 patients irradiated with LGK in 1993-2003. The patients were divided in two subgroups: the first subgroup followed prospectively (45 patients), irradiated with a mean dose to pituitary <15 Gy; the second subgroup followed retrospectively 1993-2001 and prospectively 2001-2009 (40 patients), irradiated with a mean dose to pituitary >15 Gy. Serum TSH, free thyroxine, testosterone or 17β-oestradiol, IGF1, prolactin and cortisol levels were evaluated before and every 6 months after LGK irradiation. Hypopituitarism after LGK irradiation developed only in 1 out of 45 (2.2%) patients irradiated with a mean dose to pituitary <15 Gy, in contrast to 72.5% patients irradiated with a mean dose to pituitary >15 Gy. The radiation dose to the distal infundibulum was found as an independent factor of hypopituitarism with calculated maximum safe dose of 17 Gy. Keeping the mean radiation dose to pituitary under 15 Gy and the dose to the distal infundibulum under 17 Gy prevents the development of hypopituitarism following LGK irradiation.

  13. Gamma knife radiosurgery for symptomatic brainstem intra-axial cavernous malformations.

    PubMed

    Park, Seong-Hyun; Hwang, Sung-Kyoo

    2013-12-01

    The purpose of this study was to evaluate the efficacy and safety of gamma knife radiosurgery (GKRS) for the treatment of symptomatic brainstem intra-axial cavernous malformations (CMs) associated with high surgical morbidity. Twenty-one patients with symptomatic brainstem intra-axial CMs were treated by GKRS between 2005 and 2010. One patient was lost to follow-up. The median age of the patients was 39.5 years (range, 24-69 years). All patients had experienced 1 or more symptomatic hemorrhages before GKRS (range, 1-3). The median marginal radiation dose was 13 Gy, and the median volume of the malformation was 0.56 mL. The median follow-up period after radiosurgery was 32 months (range, 12-82 months; mean, 38.9 months). Before GKRS, 31 hemorrhages (1.55 per patient) were observed. The annual hemorrhage rate before GKRS was 39.5%, excluding the first hemorrhage. After GKRS, 1 hemorrhage (0.05 per patient) was identified. It occurred 6 months after radiosurgery. The patient showed complete recovery to a premorbid status with steroid medication. The annual hemorrhage rate after GKRS was 8.2% for the first 2 years. After the expected latency period, no hemorrhages were identified. One patient (5%) exhibited permanent paresthesia, which was a new neurologic symptom in absence of any hemorrhagic event, after the radiosurgery. GKRS seems to be relatively effective and safe for reducing the rebleeding rate of brainstem intra-axial CMs that have high surgical risk. Careful selection of a low marginal dose and an optimal radiosurgical technique are helpful to achieve good outcomes. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Evolution of gamma knife capsulotomy for intractable obsessive-compulsive disorder.

    PubMed

    Miguel, Euripedes C; Lopes, Antonio C; McLaughlin, Nicole C R; Norén, Georg; Gentil, André F; Hamani, Clement; Shavitt, Roseli G; Batistuzzo, Marcelo C; Vattimo, Edoardo F Q; Canteras, Miguel; De Salles, Antonio; Gorgulho, Alessandra; Salvajoli, João Victor; Fonoff, Erich Talamoni; Paddick, Ian; Hoexter, Marcelo Q; Lindquist, Christer; Haber, Suzanne N; Greenberg, Benjamin D; Sheth, Sameer A

    2018-05-09

    For more than half a century, stereotactic neurosurgical procedures have been available to treat patients with severe, debilitating symptoms of obsessive-compulsive disorder (OCD) that have proven refractory to extensive, appropriate pharmacological, and psychological treatment. Although reliable predictors of outcome remain elusive, the establishment of narrower selection criteria for neurosurgical candidacy, together with a better understanding of the functional neuroanatomy implicated in OCD, has resulted in improved clinical efficacy for an array of ablative and non-ablative intervention techniques targeting the cingulum, internal capsule, and other limbic regions. It was against this backdrop that gamma knife capsulotomy (GKC) for OCD was developed. In this paper, we review the history of this stereotactic radiosurgical procedure, from its inception to recent advances. We perform a systematic review of the existing literature and also provide a narrative account of the evolution of the procedure, detailing how the procedure has changed over time, and has been shaped by forces of evidence and innovation. As the procedure has evolved and adverse events have decreased considerably, favorable response rates have remained attainable for approximately one-half to two-thirds of individuals treated at experienced centers. A reduction in obsessive-compulsive symptom severity may result not only from direct modulation of OCD neural pathways but also from enhanced efficacy of pharmacological and psychological therapies working in a synergistic fashion with GKC. Possible complications include frontal lobe edema and even the rare formation of delayed radionecrotic cysts. These adverse events have become much less common with new radiation dose and targeting strategies. Detailed neuropsychological assessments from recent studies suggest that cognitive function is not impaired, and in some domains may even improve following treatment. We conclude this review with

  15. Validation of a pretreatment delivery quality assurance method for the CyberKnife Synchrony system.

    PubMed

    Mastella, E; Vigorito, S; Rondi, E; Piperno, G; Ferrari, A; Strata, E; Rozza, D; Jereczek-Fossa, B A; Cattani, F

    2016-08-01

    To evaluate the geometric and dosimetric accuracies of the CyberKnife Synchrony respiratory tracking system (RTS) and to validate a method for pretreatment patient-specific delivery quality assurance (DQA). An EasyCube phantom was mounted on the ExacTrac gating phantom, which can move along the superior-inferior (SI) axis of a patient to simulate a moving target. The authors compared dynamic and static measurements. For each case, a Gafchromic EBT3 film was positioned between two slabs of the EasyCube, while a PinPoint ionization chamber was placed in the appropriate space. There were three steps to their evaluation: (1) the field size, the penumbra, and the symmetry of six secondary collimators were measured along the two main orthogonal axes. Dynamic measurements with deliberately simulated errors were also taken. (2) The delivered dose distributions (from step 1) were compared with the planned ones, using the gamma analysis method. The local gamma passing rates were evaluated using three acceptance criteria: 3% local dose difference (LDD)/3 mm, 2%LDD/2 mm, and 3%LDD/1 mm. (3) The DQA plans for six clinical patients were irradiated in different dynamic conditions, to give a total of 19 cases. The measured and planned dose distributions were evaluated with the same gamma-index criteria used in step 2 and the measured chamber doses were compared with the planned mean doses in the sensitive volume of the chamber. (1) A very slight enlargement of the field size and of the penumbra was observed in the SI direction (on average <1 mm), in line with the overall average CyberKnife system error for tracking treatments. (2) Comparison between the planned and the correctly delivered dose distributions confirmed the dosimetric accuracy of the RTS for simple plans. The multicriteria gamma analysis was able to detect the simulated errors, proving the robustness of their method of analysis. (3) All of the DQA clinical plans passed the tests, both in static and dynamic conditions

  16. Gamma knife radiosurgery for Cushing's disease and Nelson's syndrome.

    PubMed

    Marek, Josef; Ježková, Jana; Hána, Václav; Kršek, Michal; Liščák, Roman; Vladyka, Vilibald; Pecen, Ladislav

    2015-06-01

    This paper presents our 18 years of experience in treating ACTH secreting adenomas (Cushing's disease and Nelson's syndrome) using the Leksell gamma knife (LGK) irradiation. Twenty-six patients with Cushing's disease were followed-up after LGK irradiation for 48-216 months (median 78 months). Seventeen patients had undergone previous surgery, in nine patients LGK irradiation was the primary therapy. Furthermore, 14 patients with Nelson's syndrome were followed-up for 30-204 months (median 144 months). LGK treatment resulted in hormonal normalization in 80.7 % of patients with Cushing's disease. Time to normalization was 6-54 months (median 30 months). The volume of the adenoma decreased in 92.3% (in 30.7% disappeared completely). There was no recurrence of the disease. In all 14 patients with Nelson's syndrome ACTH levels decreased (in two patients fully normalized) their ACTH levels. When checked up 5-10 years after irradiation regrowth of the adenoma was only detected in one patient (9.1%), in 27.3% adenoma volume remained unchanged, in 45.4% adenoma volume decreased and in 18.2% adenoma completely disappeared. Hypopituitarism did not develop in any patient where the critical dose to the pituitary and distal infundibulum was respected. LGK radiation represents an effective and well-tolerated option for the treatment of patients with Cushing's disease after unsuccessful surgery and may be valuable even as a primary treatment in patients who are not suitable for, or refuse, surgery. In the case of Nelson's syndrome it is possible to impede tumorous growth and control the size of the adenoma in almost all patients.

  17. Communicating Hydrocephalus Associated with Intracranial Schwannoma Treated by Gamma Knife Radiosurgery.

    PubMed

    Park, Chang Kyu; Lee, Sung Ho; Choi, Man Kyu; Choi, Seok Keun; Park, Bong Jin; Lim, Young Jin

    2016-05-01

    Gamma knife radiosurgery (GKRS) has been established as an effective and safe treatment for intracranial schwannoma. However, serious complications can occur after GKRS, including hydrocephalus. The pathophysiology and risk factors of this disorder are not yet fully understood. The objective of the study was to assess potential risk factors for hydrocephalus after GKRS. We retrospectively reviewed the medical radiosurgical records of 244 patients who underwent GKRS to treat intracranial schwannoma. The following parameters were analyzed as potential risk factors for hydrocephalus after GKRS: age, sex, target volume, irradiation dose, prior tumor resection, treatment technique, and tumor enhancement pattern. The tumor enhancement pattern was divided into 2 groups: group A (homogeneous enhancement) and group B (heterogeneous or rim enhancement). Of the 244 patients, 14 of them (5.7%) developed communicating hydrocephalus. Communicating hydrocephalus occurred within 2 years after GKRS in most patients (92.8%). No significant association was observed between any of the parameters investigated and the development of hydrocephalus, with the exception of tumor enhancement pattern. Group B exhibited a statistically significant difference by univariate analysis (P = 0.002); this difference was also significant by multivariate analysis (P = 0.006). Because hydrocephalus is curable, patients should be closely monitored for the development of this disorder after GKRS. In particular, patients with intracranial schwannomas with irregular enhancement patterns or cysts should be meticulously observed. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Local tumour control and eye preservation after gamma-knife radiosurgery of choroidal melanomas.

    PubMed

    Wackernagel, Werner; Holl, Etienne; Tarmann, Lisa; Mayer, Christoph; Avian, Alexander; Schneider, Mona; Kapp, Karin S; Langmann, Gerald

    2014-02-01

    To report on local tumour control and eye preservation after gamma knife radiosurgery (GK-RS) to treat choroidal melanomas. A total of 189 patients with choroidal melanoma were treated with GK-RS, with treatment doses between 25 and 80 Grays. The main outcome measures of our retrospective analysis were local tumour control, time to recurrence, eye retention rate and the reason for and time to secondary enucleation. Patient-associated, tumour-associated and treatment-associated parameters were evaluated as potential risk factors. Local tumour control was achieved in 94.4% of patients. The estimated tumour control rates were 97.6% at 1 year, 94.2% at 5 years and 92.4% at 10 years after treatment. Recurrence was observed between 3.1 months and 60.7 months post-treatment (median: 13.5 months). Advanced tumour stage (Tumour, Node, Metastasis (TNM) 3-4) was the most important risk factor for recurrence (Fine-Gray model; subhazard ratio, SHR: 3.3; p=0.079). The treatment dose was not related to tumour recurrence. The eye preservation rate was 81.6% at 5 years after treatment, remaining stable thereafter. Twenty-five eyes (14.1%) had to be enucleated at between 17 days and 68.0 months (median: 13.9 months) after GK-RS, and advanced tumour stage (Cox model; p=0.005), treatment dose (p=0.048), pretreatment visual acuity (p=0.016), and retinal detachment (p=0.027) were risk factors for requiring enucleation. GK-RS achieved a high tumour control rate, comparable to linear accelerator-based radiotherapy. Advanced TNM stage was a predictive risk factor for tumour recurrence and for secondary enucleation after GK-RS. Lower treatment doses were unrelated to tumour recurrence, although they were associated with an improved eye retention rate.

  19. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Gamma Knife radiosurgery for hemangioma of the cavernous sinus.

    PubMed

    Lee, Cheng-Chia; Sheehan, Jason P; Kano, Hideyuki; Akpinar, Berkcan; Martinez-Alvarez, Roberto; Martinez-Moreno, Nuria; Guo, Wan-Yuo; Lunsford, L Dade; Liu, Kang-Du

    2017-05-01

    OBJECTIVE Cavernous sinus hemangiomas (CSHs) are rare vascular tumors. A direct microsurgical approach usually results in massive hemorrhage and incomplete tumor resection. Although stereotactic radiosurgery (SRS) has emerged as a therapeutic alternative to microsurgery, outcome studies are few. Authors of the present study evaluated the role of SRS for CSH. METHODS An international multicenter study was conducted to review outcome data in 31 patients with CSH. Eleven patients had initial microsurgery before SRS, and the other 20 patients (64.5%) underwent Gamma Knife SRS as the primary management for their CSH. Median age at the time of radiosurgery was 47 years, and 77.4% of patients had cranial nerve dysfunction before SRS. Patients received a median tumor margin dose of 12.6 Gy (range 12-19 Gy) at a median isodose of 55%. RESULTS Tumor regression was confirmed by imaging in all 31 patients, and all patients had greater than 50% reduction in tumor volume at 6 months post-SRS. No patient had delayed tumor growth, new cranial neuropathy, visual function deterioration, adverse radiation effects, or hypopituitarism after SRS. Twenty-four patients had presented with cranial nerve disorders before SRS, and 6 (25%) of them had gradual improvement. Four (66.7%) of the 6 patients with orbital symptoms had symptomatic relief at the last follow-up. CONCLUSIONS Stereotactic radiosurgery was effective in reducing the volume of CSH and attaining long-term tumor control in all patients at a median of 40 months. The authors' experience suggests that SRS is a reasonable primary and adjuvant treatment modality for patients in whom a CSH is diagnosed.

  1. Determination of small field synthetic single-crystal diamond detector correction factors for CyberKnife, Leksell Gamma Knife Perfexion and linear accelerator.

    PubMed

    Veselsky, T; Novotny, J; Pastykova, V; Koniarova, I

    2017-12-01

    The aim of this study was to determine small field correction factors for a synthetic single-crystal diamond detector (PTW microDiamond) for routine use in clinical dosimetric measurements. Correction factors following small field Alfonso formalism were calculated by comparison of PTW microDiamond measured ratio M Qclin fclin /M Qmsr fmsr with Monte Carlo (MC) based field output factors Ω Qclin,Qmsr fclin,fmsr determined using Dosimetry Diode E or with MC simulation itself. Diode measurements were used for the CyberKnife and Varian Clinac 2100C/D linear accelerator. PTW microDiamond correction factors for Leksell Gamma Knife (LGK) were derived using MC simulated reference values from the manufacturer. PTW microDiamond correction factors for CyberKnife field sizes 25-5 mm were mostly smaller than 1% (except for 2.9% for 5 mm Iris field and 1.4% for 7.5 mm fixed cone field). The correction of 0.1% and 2.0% for 8 mm and 4 mm collimators, respectively, needed to be applied to PTW microDiamond measurements for LGK Perfexion. Finally, PTW microDiamond M Qclin fclin /M Qmsr fmsr for the linear accelerator varied from MC corrected Dosimetry Diode data by less than 0.5% (except for 1 × 1 cm 2 field size with 1.3% deviation). Regarding low resulting correction factor values, the PTW microDiamond detector may be considered an almost ideal tool for relative small field dosimetry in a large variety of stereotactic and radiosurgery treatment devices. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  2. Stereotactic radiosurgery XX: ocular neuromyotonia in association with gamma knife radiosurgery

    PubMed Central

    McQuillan, Joe; Plowman, P Nicholas; MacDougall, Niall; Blackburn, Philip; Sabin, H Ian; Ali, Nadeem; Drake, William M

    2015-01-01

    Summary We report three patients who developed symptoms and signs of ocular neuromyotonia (ONM) 3–6 months after receiving gamma knife radiosurgery (GKS) for functioning pituitary tumours. All three patients were complex, requiring multi-modality therapy and all had received prior external irradiation to the sellar region. Although direct causality cannot be attributed, the timing of the development of the symptoms would suggest that the GKS played a contributory role in the development of this rare problem, which we suggest clinicians should be aware of as a potential complication. Learning points GKS can cause ONM, presenting as intermittent diplopia.ONM can occur quite rapidly after treatment with GKS.Treatment with carbamazepine is effective and improve patient's quality of life. PMID:26294961

  3. Clinical Outcomes of Gamma Knife Radiosurgery in the Treatment of Patients with Trigeminal Neuralgia

    PubMed Central

    Elaimy, Ameer L.; Hanson, Peter W.; Lamoreaux, Wayne T.; Mackay, Alexander R.; Demakas, John J.; Fairbanks, Robert K.; Cooke, Barton S.; Thumma, Sudheer R.; Lee, Christopher M.

    2012-01-01

    Since its introduction by Leksell, Gamma Knife radiosurgery (GKRS) has become increasingly popular as a management approach for patients diagnosed with trigeminal neuralgia (TN). For this reason, we performed a modern review of the literature analyzing the efficacy of GKRS in the treatment of patients who suffer from TN. For patients with medically refractory forms of the condition, GKRS has proven to be an effective initial and repeat treatment option. Cumulative research suggests that patients treated a single time with GKRS exhibit similar levels of facial pain control when compared to patients treated multiple times with GKRS. However, patients treated on multiple occasions with GKRS are more likely to experience facial numbness and other facial sensory changes when compared to patients treated once with GKRS. Although numerous articles have reported MVD to be superior to GKRS in achieving facial pain relief, the findings of these comparison studies are weakened by the vast differences in patient age and comorbidities between the two studied groups and cannot be considered conclusive. Questions remain regarding optimal GKRS dosing and targeting strategies, which warrants further investigation into this controversial matter. PMID:22229034

  4. Assessment of the accuracy and stability of frameless gamma knife radiosurgery.

    PubMed

    Chung, Hyun-Tai; Park, Woo-Yoon; Kim, Tae Hoon; Kim, Yong Kyun; Chun, Kook Jin

    2018-06-03

    The aim of this study was to assess the accuracy and stability of frameless gamma knife radiosurgery (GKRS). The accuracies of the radiation isocenter and patient couch movement were evaluated by film dosimetry with a half-year cycle. Radiation isocenter assessment with a diode detector and cone-beam computed tomography (CBCT) image accuracy tests were performed daily with a vendor-provided tool for one and a half years after installation. CBCT image quality was examined twice a month with a phantom. The accuracy of image coregistration using CBCT images was studied using magnetic resonance (MR) and computed tomography (CT) images of another phantom. The overall positional accuracy was measured in whole procedure tests using film dosimetry with an anthropomorphic phantom. The positional errors of the radiation isocenter at the center and at an extreme position were both less than 0.1 mm. The three-dimensional deviation of the CBCT coordinate system was stable for one and a half years (mean 0.04 ± 0.02 mm). Image coregistration revealed a difference of 0.2 ± 0.1 mm between CT and CBCT images and a deviation of 0.4 ± 0.2 mm between MR and CBCT images. The whole procedure test of the positional accuracy of the mask-based irradiation revealed an accuracy of 0.5 ± 0.6 mm. The radiation isocenter accuracy, patient couch movement accuracy, and Gamma Knife Icon CBCT accuracy were all approximately 0.1 mm and were stable for one and a half years. The coordinate system assigned to MR images through coregistration was more accurate than the system defined by fiducial markers. Possible patient motion during irradiation should be considered when evaluating the overall accuracy of frameless GKRS. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  5. Gamma Knife radiosurgery for brain metastases from pulmonary large cell neuroendocrine carcinoma: a Japanese multi-institutional cooperative study (JLGK1401).

    PubMed

    Kawabe, Takuya; Yamamoto, Masaaki; Sato, Yasunori; Yomo, Shoji; Kondoh, Takeshi; Nagano, Osamu; Serizawa, Toru; Tsugawa, Takahiko; Okamoto, Hisayo; Akabane, Atsuya; Aita, Kazuyasu; Sato, Manabu; Jokura, Hidefumi; Kawagishi, Jun; Shuto, Takashi; Kawai, Hideya; Moriki, Akihito; Kenai, Hiroyuki; Iwai, Yoshiyasu; Gondo, Masazumi; Hasegawa, Toshinori; Yasuda, Soichiro; Kikuchi, Yasuhiro; Nagatomo, Yasushi; Watanabe, Shinya; Hashimoto, Naoya

    2016-12-01

    OBJECTIVE In 1999, the World Health Organization categorized large cell neuroendocrine carcinoma (LCNEC) of the lung as a variant of large cell carcinoma, and LCNEC now accounts for 3% of all lung cancers. Although LCNEC is categorized among the non-small cell lung cancers, its biological behavior has recently been suggested to be very similar to that of a small cell pulmonary malignancy. The clinical outcome for patients with LCNEC is generally poor, and the optimal treatment for this malignancy has not yet been established. Little information is available regarding management of LCNEC patients with brain metastases (METs). This study aimed to evaluate the efficacy of Gamma Knife radiosurgery (GKRS) for patients with brain METs from LCNEC. METHODS The Japanese Leksell Gamma Knife Society planned this retrospective study in which 21 Gamma Knife centers in Japan participated. Data from 101 patients were reviewed for this study. Most of the patients with LCNEC were men (80%), and the mean age was 67 years (range 39-84 years). Primary lung tumors were reported as well controlled in one-third of the patients. More than half of the patients had extracranial METs. Brain metastasis and lung cancer had been detected simultaneously in 25% of the patients. Before GKRS, brain METs had manifested with neurological symptoms in 37 patients. Additionally, prior to GKRS, resection was performed in 17 patients and radiation therapy in 10. A small cell lung carcinoma-based chemotherapy regimen was chosen for 48 patients. The median lesion number was 3 (range 1-33). The median cumulative tumor volume was 3.5 cm 3 , and the median radiation dose was 20.0 Gy. For statistical analysis, the standard Kaplan-Meier method was used to determine post-GKRS survival. Competing risk analysis was applied to estimate GKRS cumulative incidences of maintenance of neurological function and death, local recurrence, appearance of new lesions, and complications. RESULTS The overall median survival time

  6. Hypertrophic olivary degeneration following surgical resection or gamma knife radiosurgery of brainstem cavernous malformations: an 11-case series and a review of literature.

    PubMed

    Yun, Jung-Ho; Ahn, Jae Sung; Park, Jung Cheol; Kwon, Do Hoon; Kwun, Byung Duk; Kim, Chang Jin

    2013-03-01

    We describe 11 patients with hypertrophic olivary degeneration (HOD) after surgical resection or gamma knife radiosurgery for brainstem cavernous malformations. In addition, we statistically analyzed the predicting factors associated with the development of HOD. From January 2001 to May 2011, a total of 73 patients (30 in the surgical group and 43 in the radiosurgery group) with brainstem cavernous malformations were treated in our institute. Of them, 11 patients (incidence: 15 %) developed HOD with high signal intensity on T2-weighted MRI during follow-up. The predicting factors (location, size, age, and treatment method) associated with the development of HOD were statistically analyzed. Among the 11 HOD patients, seven patients received surgical resection and four patients received gamma knife radiosurgery. Six patients had bilateral HOD and the remaining five patients had unilateral HOD. Overall HOD-associated symptoms presented in four patients, including three palatal tremors and one ataxia. In all four patients with symptoms, these symptoms disappeared incompletely within the clinical follow-up period. The size of the cavernous malformation, age of patient, and treatment methods were not significantly correlated with the development of HOD. A significantly higher incidence of HOD was associated with midbrain cavernous malformations than with pontine or medulla cavernous malformations. HOD should be recognized as a non-infrequent complication of surgical resection or gamma knife radiosurgery within the brainstem, especially for midbrain cavernous malformations. In addition, to the best of our knowledge, this is the first report on HOD development after radiosurgery.

  7. Therapeutic Effect of Gamma Knife Radiosurgery for Multiple Brain Metastases

    PubMed Central

    Lee, Chul-Kyu; Lee, Sang Ryul; Cho, Jin Mo; Yang, Kyung Ah

    2011-01-01

    Objective The aim of this study is to evaluate the therapeutic effects of gamma knife radiosurgery (GKRS) in patients with multiple brain metastases and to investigate prognostic factors related to treatment outcome. Methods We retrospectively reviewed clinico-radiological and dosimetric data of 36 patients with 4-14 brain metastases who underwent GKRS for 264 lesions between August 2008 and April 2011. The most common primary tumor site was the lung (n=22), followed by breast (n=7). At GKRS, the median Karnofsky performance scale score was 90 and the mean tumor volume was 1.2 cc (0.002-12.6). The mean prescription dose of 17.8 Gy was delivered to the mean 61.1% isodose line. Among 264 metastases, 175 lesions were assessed for treatment response by at least one imaging follow-up. Results The overall median survival after GKRS was 9.1±1.7 months. Among various factors, primary tumor control was a significant prognostic factor (11.1±1.3 months vs. 3.3±2.4 months, p=0.031). The calculated local tumor control rate at 6 and 9 months after GKRS were 87.9% and 84.2%, respectively. Paddick's conformity index (>0.75) was significantly related to local tumor control. The actuarial peritumoral edema reduction rate was 22.4% at 6 months. Conclusion According to our results, GKRS can provide beneficial effect for the patients with multiple (4 or more) brain metastases, when systemic cancer is controlled. And, careful dosimetry is essential for local tumor control. Therefore, GKRS can be considered as one of the treatment modalities for multiple brain metastase. PMID:22102945

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Little, Andrew S.; Shetter, Andrew G.; Shetter, Mary E.

    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 usingmore » 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.« less

  9. Evaluation of stability of stereotactic space defined by cone-beam CT for the Leksell Gamma Knife Icon.

    PubMed

    AlDahlawi, Ismail; Prasad, Dheerendra; Podgorsak, Matthew B

    2017-05-01

    The Gamma Knife Icon comes with an integrated cone-beam CT (CBCT) for image-guided stereotactic treatment deliveries. The CBCT can be used for defining the Leksell stereotactic space using imaging without the need for the traditional invasive frame system, and this allows also for frameless thermoplastic mask stereotactic treatments (single or fractionated) with the Gamma Knife unit. In this study, we used an in-house built marker tool to evaluate the stability of the CBCT-based stereotactic space and its agreement with the standard frame-based stereotactic space. We imaged the tool with a CT indicator box using our CT-simulator at the beginning, middle, and end of the study period (6 weeks) for determining the frame-based stereotactic space. The tool was also scanned with the Icon's CBCT on a daily basis throughout the study period, and the CBCT images were used for determining the CBCT-based stereotactic space. The coordinates of each marker were determined in each CT and CBCT scan using the Leksell GammaPlan treatment planning software. The magnitudes of vector difference between the means of each marker in frame-based and CBCT-based stereotactic space ranged from 0.21 to 0.33 mm, indicating good agreement of CBCT-based and frame-based stereotactic space definition. Scanning 4-month later showed good prolonged stability of the CBCT-based stereotactic space definition. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  10. Neurological Change after Gamma Knife Radiosurgery for Brain Metastases Involving the Motor Cortex

    PubMed Central

    Park, Chang-Yong; Choi, Hyun-Yong; Lee, Sang-Ryul; Roh, Tae Hoon; Seo, Mi-Ra

    2016-01-01

    Background Although Gamma Knife radiosurgery (GKRS) can provide beneficial therapeutic effects for patients with brain metastases, lesions involving the eloquent areas carry a higher risk of neurologic deterioration after treatment, compared to those located in the non-eloquent areas. We aimed to investigate neurological change of the patients with brain metastases involving the motor cortex (MC) and the relevant factors related to neurological deterioration after GKRS. Methods We retrospectively reviewed clinical, radiological and dosimetry data of 51 patients who underwent GKRS for 60 brain metastases involving the MC. Prior to GKRS, motor deficits existed in 26 patients (50.9%). The mean target volume was 3.2 cc (range 0.001–14.1) at the time of GKRS, and the mean prescription dose was 18.6 Gy (range 12–24 Gy). Results The actuarial median survival time from GKRS was 19.2±5.0 months. The calculated local tumor control rates at 6 and 12 months after GKRS were 89.7% and 77.4%, respectively. During the median clinical follow-up duration of 12.3±2.6 months (range 1–54 months), 18 patients (35.3%) experienced new or worsened neurologic deficits with a median onset time of 2.5±0.5 months (range 0.3–9.7 months) after GKRS. Among various factors, prescription dose (>20 Gy) was a significant factor for the new or worsened neurologic deficits in univariate (p=0.027) and multivariate (p=0.034) analysis. The managements of 18 patients were steroid medication (n=10), boost radiation therapy (n=5), and surgery (n=3), and neurological improvement was achieved in 9 (50.0%). Conclusion In our series, prescription dose (>20 Gy) was significantly related to neurological deterioration after GKRS for brain metastases involving the MC. Therefore, we suggest that careful dose adjustment would be required for lesions involving the MC to avoid neurological deterioration requiring additional treatment in the patients with limited life expectancy. PMID:27867921

  11. WE-G-BRA-08: Failure Modes and Effects Analysis (FMEA) for Gamma Knife Radiosurgery

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Y; Bhatnagar, J; Bednarz, G

    2015-06-15

    Purpose: To perform a failure modes and effects analysis (FMEA) study for Gamma Knife (GK) radiosurgery processes at our institution based on our experience with the treatment of more than 13,000 patients. Methods: A team consisting of medical physicists, nurses, radiation oncologists, neurosurgeons at the University of Pittsburgh Medical Center and an external physicist expert was formed for the FMEA study. A process tree and a failure mode table were created for the GK procedures using the Leksell GK Perfexion and 4C units. Three scores for the probability of occurrence (O), the severity (S), and the probability of no detectionmore » (D) for failure modes were assigned to each failure mode by each professional on a scale from 1 to 10. The risk priority number (RPN) for each failure mode was then calculated (RPN = OxSxD) as the average scores from all data sets collected. Results: The established process tree for GK radiosurgery consists of 10 sub-processes and 53 steps, including a sub-process for frame placement and 11 steps that are directly related to the frame-based nature of the GK radiosurgery. Out of the 86 failure modes identified, 40 failure modes are GK specific, caused by the potential for inappropriate use of the radiosurgery head frame, the imaging fiducial boxes, the GK helmets and plugs, and the GammaPlan treatment planning system. The other 46 failure modes are associated with the registration, imaging, image transfer, contouring processes that are common for all radiation therapy techniques. The failure modes with the highest hazard scores are related to imperfect frame adaptor attachment, bad fiducial box assembly, overlooked target areas, inaccurate previous treatment information and excessive patient movement during MRI scan. Conclusion: The implementation of the FMEA approach for Gamma Knife radiosurgery enabled deeper understanding of the overall process among all professionals involved in the care of the patient and helped identify

  12. Gamma Knife radiosurgery for the treatment of intracranial dural arteriovenous fistulas

    PubMed Central

    Dmytriw, Adam A; Schwartz, Michael L; Cusimano, Michael D; Mendes Pereira, Vitor; Krings, Timo; Tymianski, Michael; Radovanovic, Ivan

    2016-01-01

    Background Intracranial dural arteriovenous fistulae (DAVF) may present a treatment challenge. Endovascular embolization is in most cases the first line of treatment but does not always achieve cure. Gamma Knife (GK) radiosurgery represents an alternative treatment option, and the purpose of this study was to further evaluate its utility. Methods We reviewed all cases of DAVF treated between 2009 and 2016 at our institution with GK radiosurgery independently, or following failed/refused endovascular or surgical management. Patients’ clinical files, radiological images, catheter angiograms, and surgical DAVF disconnection reports were retrospectively reviewed. Results Sixteen DAVF (14 patients) treated by GK radiosurgery were identified. Eleven fistulae were aggressive and five were benign. Marginal doses ranged from 15 to 25 Gy. Target volumes ranged from 0.04 to 4.47 cm3. In all symptomatic patients, GK treatment resulted in symptom palliation. In 13/15 lesions, cure of symptoms (86.0%) was reported. One lesion was asymptomatic. Angiographic cure was achieved in eight cases (50%), small residual DAVF occurred in four, and four were unchanged. One patient developed headache that resolved at one year. No hemorrhage occurred during the follow-up period. There was no significant association between Borden type and cure rate. Prior failed endovascular treatment and small target volume were associated with lower rates of cure. Conclusions Stereotactic radiosurgery is viable treatment for DAVF. It is very effective in palliating symptoms as a de novo approach or adjunctive to endovascular therapy. In our experience it is only somewhat effective in achieving complete angiographic cure. PMID:28156167

  13. Vestibular schwannomas: clinical results and quality of life after microsurgery or gamma knife radiosurgery.

    PubMed

    Myrseth, Erling; Møller, Per; Pedersen, Paal-Henning; Vassbotn, Flemming S; Wentzel-Larsen, Tore; Lund-Johansen, Morten

    2005-05-01

    The aim of the present study was to evaluate the overall treatment efficacy (tumor control, facial nerve function, complications) and quality of life for patients treated primarily for unilateral vestibular schwannomas of 30 mm or less, either by microsurgery or by gamma knife (GK) radiosurgery. The results for the two treatment groups are compared with each other, with main emphasis on the long-term quality of life. This is a retrospective study of 189 consecutive patients, 86 treated by microsurgery and 103 by gamma knife. The mean observation time was 5.9 years. All patients had a magnetic resonance imaging scan and clinical evaluation performed toward the end of the study. To evaluate the quality of life, we used two standardized questionnaires, the Glasgow Benefit Inventory and Short-Form 36. The questionnaires were sent to the 168 living patients. The reply rate was 83.3%. A total of 79.8% of the patients in the microsurgery group and 94.8% of the GK patients had a good facial nerve function (House-Brackmann Grade 1-2). Hearing was usually lost after microsurgery, whereas the GK patients had preserved hearing, which often became reduced over the years after the treatment. The treatment efficacy, defined as no need for additional treatment, was similar for the two treatment modalities. Quality of life was reduced compared with normative data, being most reduced in the microsurgery group. Some of the quality of life questions showed an association with facial nerve function and sex. Posttreatment facial nerve function, hearing, complication rates, and quality of life were all significantly in favor of GK radiosurgery.

  14. [Development of external quality control protocol for CyberKnife beams dosimetry: preliminary tests multicentre].

    PubMed

    Guinement, L; Marchesi, V; Veres, A; Lacornerie, T; Buchheit, I; Peiffert, D

    2013-01-01

    To develop an external quality control procedure for CyberKnife(®) beams. This work conducted in Nancy, has included a test protocol initially drawn by the medical physicist of Nancy and Lille in collaboration with Equal-Estro Laboratory. A head and neck anthropomorphic phantom and a water-equivalent homogeneous cubic plastic test-object, so-called "MiniCube", have been used. Powder and solid thermoluminescent dosimeters as well as radiochromic films have been used to perform absolute and relative dose studies, respectively. The comparison between doses calculated by Multiplan treatment planning system and measured doses have been studied in absolute dose. The dose distributions measured with films and treatment planning system calculations have been compared via the gamma function, configured with different tolerance criteria. This work allowed, via solid thermoluminescent dosimeter measurements, verifying the beam reliability with a reproducibility of 1.7 %. The absolute dose measured in the phantom irradiated by the seven participating centres has shown an error inferior to the standard tolerance limits (± 5 %), for most of participating centres. The relative dose measurements performed at Nancy and by the Equal-Estro laboratory allowed defining the most adequate parameters for gamma index (5 %/2mm--with at least 95 % of pixels satisfying acceptability criteria: γ<1). These parameters should be independent of the film analysis software. This work allowed defining a dosimetric external quality control for CyberKnife(®) systems, based on a reproducible irradiation plan through measurements performed with thermoluminescent dosimeters and radiochromic films. This protocol should be validated by a new series of measurement and taking into account the lessons of this work. Copyright © 2013 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  15. 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.

  16. Safety and efficacy of endovascular therapy and gamma knife surgery for brain arteriovenous malformations in China: Study protocol for an observational clinical trial.

    PubMed

    Jin, Hengwei; Huo, Xiaochuan; Jiang, Yuhua; Li, Xiaolong; Li, Youxiang

    2017-09-01

    Brain arteriovenous malformations (BAVMs) are associated with high morbidity and mortality. The treatment of BAVM remains controversial. Microinvasive treatment, including endovascular therapy and gamma knife surgery, has been the first choice in many conditions. However, the overall clinical outcome of microinvasive treatment remains unknown and a prospective trial is needed. This is a prospective, non-randomized, and multicenter observational registry clinical trial to evaluate the safety and efficacy of microinvasive treatment for BAVMs. The study will require up to 400 patients in approximately 12 or more centers in China, followed for 2 years. Main subjects of this study are BAVM patients underwent endovascular therapy and/or gamma knife surgery. The trial will not affect the choice of treatment modality. The primary outcomes are perioperative complications (safety), and postoperative hemorrhage incidence rate and complete occlusion rate (efficacy). Secondary outcomes are elimination of hemorrhage risk factors (coexisting aneurysms and arteriovenous fistula), volume reduction and remission of symptoms. Safety and efficacy of endovascular therapy, gamma knife surgery, and various combination modes of the two modalities will be compared. Operative complications and outcomes at pretreatment, post-treatment, at discharge and at 3 months, 6 months and 2 years follow-up intervals will be analyzed using the modified Rankin Scale (mRS). The most confusion on BAVM treatment is whether to choose interventional therapy or medical therapy, and the choice of interventional therapy modes. This study will provide evidence for evaluating the safety and efficacy of microinvasive treatment in China, to characterize the microinvasive treatment strategy for BAVMs.

  17. Gamma Knife radiosurgery for facial nerve schwannomas: a multicenter study.

    PubMed

    Sheehan, Jason P; Kano, Hideyuki; Xu, Zhiyuan; Chiang, Veronica; Mathieu, David; Chao, Samuel; Akpinar, Berkcan; Lee, John Y K; Yu, James B; Hess, Judith; Wu, Hsiu-Mei; Chung, Wen-Yuh; Pierce, John; Missios, Symeon; Kondziolka, Douglas; Alonso-Basanta, Michelle; Barnett, Gene H; Lunsford, L Dade

    2015-08-01

    Facial nerve schwannomas (FNSs) are rare intracranial tumors, and the optimal management of these tumors remains unclear. Resection can be undertaken, but the tumor's intimate association with the facial nerve makes resection with neurological preservation quite challenging. Stereotactic radiosurgery (SRS) has been used to treat FNSs, and this study evaluates the outcome of this approach. At 8 medical centers participating in the North American Gamma Knife Consortium (NAGKC), 42 patients undergoing SRS for an FNS were identified, and clinical and radiographic data were obtained for these cases. Males outnumbered females at a ratio of 1.2:1, and the patients' median age was 48 years (range 11-76 years). Prior resection was performed in 36% of cases. The mean tumor volume was 1.8 cm(3), and a mean margin dose of 12.5 Gy (range 11-15 Gy) was delivered to the tumor. At a median follow-up of 28 months, tumor control was achieved in 36 (90%) of the 40 patients with reliable radiographic follow-up. Actuarial tumor control was 97%, 97%, 97%, and 90% at 1, 2, 3, and 5 years postradiosurgery. Preoperative facial nerve function was preserved in 38 of 42 patients, with 60% of evaluable patients having House-Brackmann scores of 1 or 2 at last follow-up. Treated patients with a House-Brackmann score of 1 to 3 were more likely to demonstrate this level of facial nerve function at last evaluation (OR 6.09, 95% CI 1.7-22.0, p = 0.006). Avoidance of temporary or permanent neurological symptoms was more likely to be achieved in patients who received a tumor margin dose of 12.5 Gy or less (log-rank test, p = 0.024) delivered to a tumor of ≤ 1 cm(3) in volume (log-rank test, p = 0.01). Stereotactic radiosurgery resulted in tumor control and neurological preservation in most FNS patients. When the tumor is smaller and the patient exhibits favorable normal facial nerve function, SRS portends a better result. The authors believe that early, upfront SRS may be the treatment of choice for

  18. Situated cognition in clinical visualization: the role of transparency in GammaKnife neurosurgery planning.

    PubMed

    Dinka, David; Nyce, James M; Timpka, Toomas

    2009-06-01

    The aim of this study was to investigate how the clinical use of visualization technology can be advanced by the application of a situated cognition perspective. The data were collected in the GammaKnife radiosurgery setting and analyzed using qualitative methods. Observations and in-depth interviews with neurosurgeons and physicists were performed at three clinics using the Leksell GammaKnife. The users' ability to perform cognitive tasks was found to be reduced each time visualizations incongruent with the particular user's perception of clinical reality were used. The main issue here was a lack of transparency, i.e. a black box problem where machine representations "stood between" users and the cognitive tasks they wanted to perform. For neurosurgeons, transparency meant their previous experience from traditional surgery could be applied, i.e. that they were not forced to perform additional cognitive work. From the view of the physicists, on the other hand, the concept of transparency was associated with mathematical precision and avoiding creating a cognitive distance between basic patient data and what is experienced as clinical reality. The physicists approached clinical visualization technology as though it was a laboratory apparatus--one that required continual adjustment and assessment in order to "capture" a quantitative clinical reality. Designers of visualization technology need to compare the cognitive interpretations generated by the new visualization systems to conceptions generated during "traditional" clinical work. This means that the viewpoint of different clinical user groups involved in a given clinical task would have to be taken into account as well. A way forward would be to acknowledge that visualization is a socio-cognitive function that has practice-based antecedents and consequences, and to reconsider what analytical and scientific challenges this presents us with.

  19. Efficacy and tolerability of gamma knife radiosurgery in acromegaly: a 10-year follow-up study.

    PubMed

    Ronchi, Cristina L; Attanasio, Roberto; Verrua, Elisa; Cozzi, Renato; Ferrante, Emanuele; Loli, Paola; Montefusco, Laura; Motti, Enrico; Ferrari, Daniela I; Giugni, Enrico; Beck-Peccoz, Paolo; Arosio, Maura

    2009-12-01

    The long-term efficacy and safety of stereotactic radiosurgery by gamma knife (GK) still remain unknown. The aim of the study was to investigate the long-term efficacy and tolerability of GK in acromegalic patients. Retrospective analysis for a median follow-up of 10 years. Thirty-five acromegalic patients from two referral centres in Milan submitted to GK (median margin dose: 20 Gy, median % isodose: 50) between 1995 and 2004. GH/IGF-I secretion, anterior pituitary function, radiological imaging and ophthalmological data. Cure rate improved over time (up to 46% at 10 years), as did the proportion of patients achieving control on somatostatin analogues (from 12.5% at baseline to 50% at 10 years). Normal IGF-I values were observed in 82% of patients at their last visit. No visual impairment, disease recurrence, tumour growth or secondary cerebral tumour occurred. Half of the patients developed one or more new deficiencies, while two patients normalized their prior failures. In particular, new onset of clinical or subclinical hypoadrenalism occurred in 12/30 patients (40%), hypothyroidism in 3/28 (11%), hypogonadism in 2/15 (13%) and GH deficiency in 2/35 (6%). GH value at the time of GK was the best negative predictor of cure and margin dose was the best positive predictor of new hypopituitarism. Over a 10-year period after GK radiosurgery, an increasing percentage of patients achieve cure, or adequate control of the disease on pharmacological therapy, at the expense of increasing novel pituitary deficiencies. © 2009 Blackwell Publishing Ltd.

  20. 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

  1. Volumetric changes and clinical outcome for petroclival meningiomas after primary treatment with Gamma Knife radiosurgery.

    PubMed

    Sadik, Zjiwar H A; Lie, Suan Te; Leenstra, Sieger; Hanssens, Patrick E J

    2018-01-26

    OBJECTIVE Petroclival meningiomas (PCMs) can cause devastating clinical symptoms due to mass effect on cranial nerves (CNs); thus, patients harboring these tumors need treatment. Many neurosurgeons advocate for microsurgery because removal of the tumor can provide relief or result in symptom disappearance. Gamma Knife radiosurgery (GKRS) is often an alternative for surgery because it can cause tumor shrinkage with improvement of symptoms. This study evaluates qualitative volumetric changes of PCM after primary GKRS and its impact on clinical symptoms. METHODS The authors performed a retrospective study of patients with PCM who underwent primary GKRS between 2003 and 2015 at the Gamma Knife Center of the Elisabeth-Tweesteden Hospital in Tilburg, the Netherlands. This study yields 53 patients. In this study the authors concentrate on qualitative volumetric tumor changes, local tumor control rate, and the effect of the treatment on trigeminal neuralgia (TN). RESULTS Local tumor control was 98% at 5 years and 93% at 7 years (Kaplan-Meier estimates). More than 90% of the tumors showed regression in volume during the first 5 years. The mean volumetric tumor decrease was 21.2%, 27.1%, and 31% at 1, 3, and 6 years of follow-up, respectively. Improvement in TN was achieved in 61%, 67%, and 70% of the cases at 1, 2, and 3 years of follow-up, respectively. This was associated with a mean volumetric tumor decrease of 25% at the 1-year follow-up to 32% at the 3-year follow-up. CONCLUSIONS GKRS for PCMs yields a high tumor control rate with a low incidence of neurological deficits. Many patients with TN due to PCM experienced improvement in TN after radiosurgery. GKRS achieves significant volumetric tumor decrease in the first years of follow-up and thereafter.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hasegawa, Toshinori, E-mail: h-toshi@komakihp.gr.jp; Kato, Takenori; Iizuka, Hiroshi

    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, 2more » 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

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Motta, Micaela, E-mail: motta.micaela@hsr.it; Vecchio, Antonella del; Attuati, Luca

    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 wasmore » 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.« less

  4. Optimization of the prescription isodose line for Gamma Knife radiosurgery using the shot within shot technique.

    PubMed

    Johnson, Perry B; Monterroso, Maria I; Yang, Fei; Mellon, Eric

    2017-11-25

    This work explores how the choice of prescription isodose line (IDL) affects the dose gradient, target coverage, and treatment time for Gamma Knife radiosurgery when a smaller shot is encompassed within a larger shot at the same stereotactic coordinates (shot within shot technique). Beam profiles for the 4, 8, and 16 mm collimator settings were extracted from the treatment planning system and characterized using Gaussian fits. The characterized data were used to create over 10,000 shot within shot configurations by systematically changing collimator weighting and choice of prescription IDL. Each configuration was quantified in terms of the dose gradient, target coverage, and beam-on time. By analyzing these configurations, it was found that there are regions of overlap in target size where a higher prescription IDL provides equivalent dose fall-off to a plan prescribed at the 50% IDL. Furthermore, the data indicate that treatment times within these regions can be reduced by up to 40%. An optimization strategy was devised to realize these gains. The strategy was tested for seven patients treated for 1-4 brain metastases (20 lesions total). For a single collimator setting, the gradient in the axial plane was steepest when prescribed to the 56-63% (4 mm), 62-70% (8 mm), and 77-84% (16 mm) IDL, respectively. Through utilization of the optimization technique, beam-on time was reduced by more than 15% in 16/20 lesions. The volume of normal brain receiving 12 Gy or above also decreased in many cases, and in only one instance increased by more than 0.5 cm 3 . This work demonstrates that IDL optimization using the shot within shot technique can reduce treatment times without degrading treatment plan quality.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ebinu, Julius O.; Lwu, Shelly; Monsalves, Eric

    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:more » 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.« less

  6. SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Neyman, G

    Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002more » vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB.« less

  7. Radon-222 related influence on ambient gamma dose.

    PubMed

    Melintescu, A; Chambers, S D; Crawford, J; Williams, A G; Zorila, B; Galeriu, D

    2018-04-03

    Ambient gamma dose, radon, and rainfall have been monitored in southern Bucharest, Romania, from 2010 to 2016. The seasonal cycle of background ambient gamma dose peaked between July and October (100-105 nSv h -1 ), with minimum values in February (75-80 nSv h -1 ), the time of maximum snow cover. Based on 10 m a.g.l. radon concentrations, the ambient gamma dose increased by around 1 nSv h -1 for every 5 Bq m -3 increase in radon. Radon variability attributable to diurnal changes in atmospheric mixing contributed less than 15 nSv h -1 to the overall variability in ambient gamma dose, a factor of 4 more than synoptic timescale changes in air mass fetch. By contrast, precipitation-related enhancements of the ambient gamma dose were 15-80 nSv h -1 . To facilitate routine analysis, and account in part for occasional equipment failure, an automated method for identifying precipitation spikes in the ambient gamma dose was developed. Lastly, a simple model for predicting rainfall-related enhancement of the ambient gamma dose is tested against rainfall observations from events of contrasting duration and intensity. Results are also compared with those from previously published models of simple and complex formulation. Generally, the model performed very well. When simulations underestimated observations the absolute difference was typically less than the natural variability in ambient gamma dose arising from atmospheric mixing influences. Consequently, combined use of the automated event detection method and the simple model of this study could enable the ambient gamma dose "attention limit" (which indicates a potential radiological emergency) to be reduced from 200 to 400% above background to 25-50%. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. 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

  9. Novel biomarker identification using metabolomic profiling to differentiate radiation necrosis and recurrent tumor following Gamma Knife radiosurgery.

    PubMed

    Lu, Alex Y; Turban, Jack L; Damisah, Eyiyemisi C; Li, Jie; Alomari, Ahmed K; Eid, Tore; Vortmeyer, Alexander O; Chiang, Veronica L

    2017-08-01

    OBJECTIVE Following an initial response of brain metastases to Gamma Knife radiosurgery, regrowth of the enhancing lesion as detected on MRI may represent either radiation necrosis (a treatment-related inflammatory change) or recurrent tumor. Differentiation of radiation necrosis from tumor is vital for management decision making but remains difficult by imaging alone. In this study, gas chromatography with time-of-flight mass spectrometry (GC-TOF) was used to identify differential metabolite profiles of the 2 tissue types obtained by surgical biopsy to find potential targets for noninvasive imaging. METHODS Specimens of pure radiation necrosis and pure tumor obtained from patient brain biopsies were flash-frozen and validated histologically. These formalin-free tissue samples were then analyzed using GC-TOF. The metabolite profiles of radiation necrosis and tumor samples were compared using multivariate and univariate statistical analysis. Statistical significance was defined as p ≤ 0.05. RESULTS For the metabolic profiling, GC-TOF was performed on 7 samples of radiation necrosis and 7 samples of tumor. Of the 141 metabolites identified, 17 (12.1%) were found to be statistically significantly different between comparison groups. Of these metabolites, 6 were increased in tumor, and 11 were increased in radiation necrosis. An unsupervised hierarchical clustering analysis found that tumor had elevated levels of metabolites associated with energy metabolism, whereas radiation necrosis had elevated levels of metabolites that were fatty acids and antioxidants/cofactors. CONCLUSIONS To the authors' knowledge, this is the first tissue-based metabolomics study of radiation necrosis and tumor. Radiation necrosis and recurrent tumor following Gamma Knife radiosurgery for brain metastases have unique metabolite profiles that may be targeted in the future to develop noninvasive metabolic imaging techniques.

  10. 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.

  11. SU-E-J-06: Additional Imaging Guidance Dose to Patient Organs Resulting From X-Ray Tubes Used in CyberKnife Image Guidance System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sullivan, A; Ding, G

    Purpose: The use of image-guided radiation therapy (IGRT) has become increasingly common, but the additional radiation exposure resulting from repeated image guidance procedures raises concerns. Although there are many studies reporting imaging dose from different image guidance devices, imaging dose for the CyberKnife Robotic Radiosurgery System is not available. This study provides estimated organ doses resulting from image guidance procedures on the CyberKnife system. Methods: Commercially available Monte Carlo software, PCXMC, was used to calculate average organ doses resulting from x-ray tubes used in the CyberKnife system. There are seven imaging protocols with kVp ranging from 60 – 120 kVmore » and 15 mAs for treatment sites in the Cranium, Head and Neck, Thorax, and Abdomen. The output of each image protocol was measured at treatment isocenter. For each site and protocol, Adult body sizes ranging from anorexic to extremely obese were simulated since organ dose depends on patient size. Doses for all organs within the imaging field-of-view of each site were calculated for a single image acquisition from both of the orthogonal x-ray tubes. Results: Average organ doses were <1.0 mGy for every treatment site and imaging protocol. For a given organ, dose increases as kV increases or body size decreases. Higher doses are typically reported for skeletal components, such as the skull, ribs, or clavicles, than for softtissue organs. Typical organ doses due to a single exposure are estimated as 0.23 mGy to the brain, 0.29 mGy to the heart, 0.08 mGy to the kidneys, etc., depending on the imaging protocol and site. Conclusion: The organ doses vary with treatment site, imaging protocol and patient size. Although the organ dose from a single image acquisition resulting from two orthogonal beams is generally insignificant, the sum of repeated image acquisitions (>100) could reach 10–20 cGy for a typical treatment fraction.« less

  12. Evaluation of Dose Uncertainty to the Target Associated With Real-Time Tracking Intensity-Modulated Radiation Therapy Using the CyberKnife Synchrony System.

    PubMed

    Iwata, Hiromitsu; Inoue, Mitsuhiro; Shiomi, Hiroya; Murai, Taro; Tatewaki, Koshi; Ohta, Seiji; Okawa, Kohei; Yokota, Naoki; Shibamoto, Yuta

    2016-02-01

    We investigated the dose uncertainty caused by errors in real-time tracking intensity-modulated radiation therapy (IMRT) using the CyberKnife Synchrony Respiratory Tracking System (SRTS). Twenty lung tumors that had been treated with non-IMRT real-time tracking using CyberKnife SRTS were used for this study. After validating the tracking error in each case, we did 40 IMRT planning using 8 different collimator sizes for the 20 patients. The collimator size was determined for each planning target volume (PTV); smaller ones were one-half, and larger ones three-quarters, of the PTV diameter. The planned dose was 45 Gy in 4 fractions prescribed at 95% volume border of the PTV. Thereafter, the tracking error in each case was substituted into calculation software developed in house and randomly added in the setting of each beam. The IMRT planning incorporating tracking errors was simulated 1000 times, and various dose data on the clinical target volume (CTV) were compared with the original data. The same simulation was carried out by changing the fraction number from 1 to 6 in each IMRT plan. Finally, a total of 240 000 plans were analyzed. With 4 fractions, the change in the CTV maximum and minimum doses was within 3.0% (median) for each collimator. The change in D99 and D95 was within 2.0%. With decreases in the fraction number, the CTV coverage rate and the minimum dose decreased and varied greatly. The accuracy of real-time tracking IMRT delivered in 4 fractions using CyberKnife SRTS was considered to be clinically acceptable. © The Author(s) 2014.

  13. Gamma Radiation Doses In Sweden

    NASA Astrophysics Data System (ADS)

    Almgren, Sara; Barregârd, Lars; Isaksson, Mats

    2008-08-01

    Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096±0.019(1 SD) and 0.092±0.016(1 SD)μSv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11±0.042(1 SD) and 0.091±0.026(1 SD)μSv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, 222Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

  14. Comparison of plan quality and delivery time between volumetric arc therapy (RapidArc) and Gamma Knife radiosurgery for multiple cranial metastases.

    PubMed

    Thomas, Evan M; Popple, Richard A; Wu, Xingen; Clark, Grant M; Markert, James M; Guthrie, Barton L; Yuan, Yu; Dobelbower, Michael C; Spencer, Sharon A; Fiveash, John B

    2014-10-01

    Volumetric modulated arc therapy (VMAT) has been shown to be feasible for radiosurgical treatment of multiple cranial lesions with a single isocenter. To investigate whether equivalent radiosurgical plan quality and reduced delivery time could be achieved in VMAT for patients with multiple intracranial targets previously treated with Gamma Knife (GK) radiosurgery. We identified 28 GK treatments of multiple metastases. These were replanned for multiarc and single-arc, single-isocenter VMAT (RapidArc) in Eclipse. The prescription for all targets was standardized to 18 Gy. Each plan was normalized for 100% prescription dose to 99% to 100% of target volume. Plan quality was analyzed by target conformity (Radiation Therapy Oncology Group and Paddick conformity indices [CIs]), dose falloff (area under the dose-volume histogram curve), as well as the V4.5, V9, V12, and V18 isodose volumes. Other end points included beam-on and treatment time. Compared with GK, multiarc VMAT improved median plan conformity (CIVMAT = 1.14, CIGK = 1.65; P < .001) with no significant difference in median dose falloff (P = .269), 12 Gy isodose volume (P = .500), or low isodose spill (P = .49). Multiarc VMAT plans were associated with markedly reduced treatment time. A predictive model of the 12 Gy isodose volume as a function of tumor number and volume was also developed. For multiple target stereotactic radiosurgery, 4-arc VMAT produced clinically equivalent conformity, dose falloff, 12 Gy isodose volume, and low isodose spill, and reduced treatment time compared with GK. Because of its similar plan quality and increased delivery efficiency, single-isocenter VMAT radiosurgery may constitute an attractive alternative to multi-isocenter radiosurgery for some patients.

  15. SU-E-T-471: Improvement of Gamma Knife Treatment Planning Through Tumor Control Probability for Metastatic Brain Tumors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, Z; Feng, Y; Lo, S

    2015-06-15

    Purpose: The dose–volume histogram (DVH) has been normally accepted as a tool for treatment plan evaluation. However, spatial information is lacking in DVH. As a supplement to the DVH in three-dimensional treatment planning, the differential DVH (DDVH) provides the spatial variation, the size and magnitude of the different dose regions within a region of interest, which can be incorporated into tumor control probability model. This study was to provide a method in evaluating and improving Gamma Knife treatment planning. Methods: 10 patients with brain metastases from different primary tumors including melanoma (#1,#4,#5, #10), breast cancer (#2), prostate cancer (#3) andmore » lung cancer (#6–9) were analyzed. By using Leksell GammaPlan software, two plans were prepared for each patient. Special attention was given to the DDVHs that were different for different plans and were used for a comparison between two plans. Dose distribution inside target and tumor control probability (TCP) based on DDVH were calculated, where cell density and radiobiological parameters were adopted from literature. The plans were compared based on DVH, DDVH and TCP. Results: Using DVH, the coverage and selectivity were the same between plans for 10 patients. DDVH were different between two plans for each patient. The paired t-test showed no significant difference in TCP between the two plans. For brain metastases from melanoma (#1, #4–5), breast cancer (#2) and lung cancer (#6–8), the difference in TCP was less than 5%. But the difference in TCP was about 6.5% for patient #3 with the metastasis from prostate cancer, 10.1% and 178.7% for two patients (#9–10) with metastasis from lung cancer. Conclusion: Although DVH provides average dose–volume information, DDVH provides differential dose– volume information with respect to different regions inside the tumor. TCP provides radiobiological information and adds additional information on improving treatment planning as well as

  16. Gamma Knife Radiosurgery of the Superior Laryngeal Neuralgia: A report of three cases.

    PubMed

    Fu, Peng; Xiong, Nan-Xiang; Abdelmaksoud, Ahmed; Huang, Yi-Zhi; Song, Guo-Bin; Zhao, Hong-Yang

    2018-05-19

    Superior laryngeal neuralgia (SLN) is a relatively rare disorder that is characterized by neck pain. There are only a few reported cases and treatment options for SLN to date. In this study, we reported 3 patients with SLN who were treated with gamma knife radiosurgery (GKRS) at the time of diagnosis. For all 3 patients, GKRS was administered using a 4-mm collimator to deliver a single shot of 80 Gy of radiation (the 100% isodose line). The target was set at the jugular foramen where the vagus and glossopharyngeal nerves emerge from the skull. Follow-up assessments were performed at 32 months,31 months, and 30 months after GKRS. The 3 patients described pain relief at 3 months, 2 days and 6 weeks. None of the patients developed neurological deficits during the follow-up period. This preliminary report provides encouraging evidence that GKRS represents an effective, safe and relatively durable noninvasive treatment option for patients with SLN. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Gamma Knife surgery in patients harboring orbital cavernous hemangiomas that were diagnosed on the basis of imaging findings.

    PubMed

    Liu, Xiaomin; Xu, Desheng; Zhang, Yipei; Liu, Dong; Song, Guoxiang

    2010-12-01

    This study was undertaken to evaluate clinical outcomes and tumor control in patients harboring orbital cavernous hemangiomas (OCHs) that had been diagnosed based on findings of imaging studies and treated by Gamma Knife surgery (GKS). Between 1995 and 2008, 23 patients harboring OCHs that had been diagnosed on the basis of imaging findings were treated using GKS; complete follow-up data are available in all cases. The median treatment volume was 1.5 cm³ (range 0.15-10.10 cm³), the median tumor margin dose was 15 Gy (range 12-20 Gy), and the median follow-up period was 12 months (range 6-120 months). A decrease in tumor size was found in 20 patients, and no tumor progression was observed after GKS. Eleven of 14 patients whose visual function had been adversely affected prior to treatment had improved visual acuity at the last assessment. Side effects of the procedure included orbital pain in 3 patients and chemosis in 2 patients. In this preliminary experience, GKS proved to be an effective treatment for OCHs diagnosed on the basis of imaging findings. Additional follow-up is necessary, and the long-term side effects of the procedure still need to be determined.

  18. Clinical Positioning Accuracy for Multisession Stereotactic Radiotherapy With the Gamma Knife Perfexion

    PubMed Central

    Young, Lori A.; Phillips, Mark H.; Cheung, Michael; Halasz, Lia M.; Rockhill, Jason K.

    2017-01-01

    Multisession stereotactic radiation therapy is increasingly being seen as a preferred option for intracranial diseases in close proximity to critical structures and for larger target volumes. The objective of this study is to investigate the reproducibility of the Extend system from Elekta. A retrospective review was conducted for all patients treated with multisession Gamma Knife between July 2010 and June 2015, including both malignant and benign lesions. Eighty-four patients were treated in this 5-year span. The average residual daily setup uncertainty was 0.48 (0.19) mm. We compare measurements of setup uncertainty from the Extend system to measurements performed with a linac-based approach previously used in our center. The Extend system has significantly reduced setup uncertainty for fractionated intracranial treatments at our institution. Positive results were observed in a small population of edentulous patients. The Extend system compares favorably with other approaches to delivering intracranial stereotactic radiotherapy and is a robust, simple-to-use, and precise method for treating multisession intracranial lesions. PMID:28514899

  19. A fully automatic approach for multimodal PET and MR image segmentation in gamma knife treatment planning.

    PubMed

    Rundo, Leonardo; Stefano, Alessandro; Militello, Carmelo; Russo, Giorgio; Sabini, Maria Gabriella; D'Arrigo, Corrado; Marletta, Francesco; Ippolito, Massimo; Mauri, Giancarlo; Vitabile, Salvatore; Gilardi, Maria Carla

    2017-06-01

    Nowadays, clinical practice in Gamma Knife treatments is generally based on MRI anatomical information alone. However, the joint use of MRI and PET images can be useful for considering both anatomical and metabolic information about the lesion to be treated. In this paper we present a co-segmentation method to integrate the segmented Biological Target Volume (BTV), using [ 11 C]-Methionine-PET (MET-PET) images, and the segmented Gross Target Volume (GTV), on the respective co-registered MR images. The resulting volume gives enhanced brain tumor information to be used in stereotactic neuro-radiosurgery treatment planning. GTV often does not match entirely with BTV, which provides metabolic information about brain lesions. For this reason, PET imaging is valuable and it could be used to provide complementary information useful for treatment planning. In this way, BTV can be used to modify GTV, enhancing Clinical Target Volume (CTV) delineation. A novel fully automatic multimodal PET/MRI segmentation method for Leksell Gamma Knife ® treatments is proposed. This approach improves and combines two computer-assisted and operator-independent single modality methods, previously developed and validated, to segment BTV and GTV from PET and MR images, respectively. In addition, the GTV is utilized to combine the superior contrast of PET images with the higher spatial resolution of MRI, obtaining a new BTV, called BTV MRI . A total of 19 brain metastatic tumors, undergone stereotactic neuro-radiosurgery, were retrospectively analyzed. A framework for the evaluation of multimodal PET/MRI segmentation is also presented. Overlap-based and spatial distance-based metrics were considered to quantify similarity concerning PET and MRI segmentation approaches. Statistics was also included to measure correlation among the different segmentation processes. Since it is not possible to define a gold-standard CTV according to both MRI and PET images without treatment response assessment

  20. Gamma Knife radiosurgery for vestibular schwannoma: clinical results at long-term follow-up in a series of 379 patients.

    PubMed

    Boari, Nicola; Bailo, Michele; Gagliardi, Filippo; Franzin, Alberto; Gemma, Marco; del Vecchio, Antonella; Bolognesi, Angelo; Picozzi, Piero; Mortini, Pietro

    2014-12-01

    Since the 1990 s, Gamma Knife radiosurgery (GKRS) has become the first-line treatment option for small- to medium-size vestibular schwannomas (VSs), especially in patients without mass effect-related symptoms and with functional hearing. The aim of this study was to assess the safety and efficacy of GKRS, in terms of tumor control, hearing preservation, and complications, in a series of 379 consecutive patients treated for VS. Of 523 patients treated at the authors' institution for VS between 2001 and 2010, the authors included 379 who underwent GKRS as the primary treatment. These patients were not affected by Type 2 neurofibromatosis and had clinical follow-up of at least 36 months. Clinical follow-up (mean and median 75.7 and 69.5 months, respectively) was performed for all patients, whereas audiometric and quantitative radiological follow-up examinations were obtained for only 153 and 219 patients, respectively. The patients' ages ranged from 23 to 85 years (mean 59 years). The mean tumor volume was 1.94 ± 2.2 cm(3) (median 1.2 cm(3), range 0.013-14.3 cm(3)), and the median margin dose was 13 Gy (range 11-15 Gy). Parameters considered as determinants of the clinical outcome were long-term tumor control, hearing preservation, and complications. A statistical analysis was performed to correlate clinical outcomes with the radiological features of the tumor, dose-planning parameters, and patient characteristics. Control of the tumor with GKRS was achieved in 97.1% of the patients. In 82.7% of the patients, the tumor volume had decreased at the last follow-up, with a mean relative reduction of 34.1%. The rate of complications was very low, with most consisting of a transient worsening of preexisting symptoms. Patients who had vertigo, balance disorders, or facial or trigeminal impairment usually experienced a complete or at least significant symptom relief after treatment. However, no significant improvement was observed in patients previously reporting tinnitus

  1. Dose fractionated gamma knife radiosurgery for large arteriovenous malformations on daily or alternate day schedule outside the linear quadratic model: Proof of concept and early results. A substitute to volume fractionation.

    PubMed

    Mukherjee, Kanchan Kumar; Kumar, Narendra; Tripathi, Manjul; Oinam, Arun S; Ahuja, Chirag K; Dhandapani, Sivashanmugam; Kapoor, Rakesh; Ghoshal, Sushmita; Kaur, Rupinder; Bhatt, Sandeep

    2017-01-01

    To evaluate the feasibility, safety and efficacy of dose fractionated gamma knife radiosurgery (DFGKRS) on a daily schedule beyond the linear quadratic (LQ) model, for large volume arteriovenous malformations (AVMs). Between 2012-16, 14 patients of large AVMs (median volume 26.5 cc) unsuitable for surgery or embolization were treated in 2-3 of DFGKRS sessions. The Leksell G frame was kept in situ during the whole procedure. 86% (n = 12) patients had radiologic evidence of bleed, and 43% (n = 6) had presented with a history of seizures. 57% (n = 8) patients received a daily treatment for 3 days and 43% (n = 6) were on an alternate day (2 fractions) regimen. The marginal dose was split into 2 or 3 fractions of the ideal prescription dose of a single fraction of 23-25 Gy. The median follow up period was 35.6 months (8-57 months). In the three-fraction scheme, the marginal dose ranged from 8.9-11.5 Gy, while in the two-fraction scheme, the marginal dose ranged from 11.3-15 Gy at 50% per fraction. Headache (43%, n = 6) was the most common early postoperative complication, which was controlled with short course steroids. Follow up evaluation of at least three years was achieved in seven patients, who have shown complete nidus obliteration in 43% patients while the obliteration has been in the range of 50-99% in rest of the patients. Overall, there was a 67.8% reduction in the AVM volume at 3 years. Nidus obliteration at 3 years showed a significant rank order correlation with the cumulative prescription dose (p 0.95, P value 0.01), with attainment of near-total (more than 95%) obliteration rates beyond 29 Gy of the cumulative prescription dose. No patient receiving a cumulative prescription dose of less than 31 Gy had any severe adverse reaction. In co-variate adjusted ordinal regression, only the cumulative prescription dose had a significant correlation with common terminology criteria for adverse events (CTCAE) severity (P value 0.04), independent of age, AVM volume

  2. DSC studies on gamma irradiated poly(vinylidene fluoride) applied to high gamma dose dosimetry

    NASA Astrophysics Data System (ADS)

    Batista, Adriana S. M.; Faria, Luiz O.

    2017-11-01

    Poly(vinylidene fluoride) homopolymer (PVDF) was investigated for use on high gamma dose dosimetry. Samples were irradiated with gamma doses ranging from 100 kGy to 3000 kGy. Differential scanning calorimetry (DSC) was used to construct an unambiguous relationship between the melting transition latent heat (LM) and the absorbed dose (D). DSC thermograms were taken immediately, 1, 2 and 8 months after the irradiation process revealing that the LMx D relationship presented no change for doses ranging from 100 to 2750 kGy. FTIR and UV-Vis spectroscopy data revealed the radio-induction of C˭O and C˭C bonds. These radio-induced bonds were responsible by the chain stiffening and chain oxidation, respectively. SEM microscopy demonstrates that the spherulitic large crystalline structures present in pristine PVDF are destroyed with doses as low as 100 kGy. The DRX analysis revealed that the main effect of high gamma doses in the crystalline structure of PVDF is to provoke a change from the pristine PVDF α-phase to the γ-phase. Both the ability to detect gamma doses in a large dose range and the low fading features make PVDF homopolymers good candidates to be investigated as high gamma dose dosimeters.

  3. 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

  4. [The Effect of Pain Relieving Intervention During Infiltration among Gamma Knife Surgery Patients for Stereotactic Frame Fixation].

    PubMed

    Jang, Young Jun; Kim, Hyeon Ok

    2018-04-01

    This study aimed to compare the effects of three interventions on pain, blood pressure, and pulse rate during infiltration anesthesia in patients about to undergo gamma knife surgeries. The three interventions employed in a university-affiliated Hospital in J City, South Korea were as follows: EMLA cream plus Vapocoolant spray (Vapocoolant, n=30), EMLA cream plus 10.0% Lidocaine spray (Lidocaine, n=30), and EMLA cream only (EMLA, n=30). The equivalent control-group pre test - post test study design was used. Pain was assessed subjectively using the numeric rating scale (NRS) and objectively using a Galvanic Skin Response (GSR) tester. NRS scores were assessed after infiltration anesthesia and the GSR was assessed during infiltration anesthesia. Blood pressure and pulse rate were assessed twice: before and after infiltration anesthesia. Data were collected between August 3, 2016 and March 24, 2017. NRS scores after infiltration anesthesia and the GSR during infiltration anesthesia were significantly lower in the Vapocoolant group than in the Lidocaine and EMLA groups (F=13.56, p<.001 and F=14.43, p<.001, respectively). The increase in systolic blood pressure (F=4.77, p=.011) and in pulse rates (F=4.78, p=.011) before and after infiltration anesthesia were significantly smaller in the Vapocoolant group than in the Lidocaine and EMLA groups; however, no significant differences were observed in diastolic blood pressures (F=1.51, p=.227). EMLA cream plus Vapocoolant spray was the most effective intervention to relieve pain and to lower increase in systolic blood pressure and pulse rate caused by infiltration anesthesia for stereotactic frame fixation. Thus, application of Vapocoolant spray in addition to EMLA cream is highly recommended as a nursing intervention for patients undergoing gamma knife surgeries. © 2018 Korean Society of Nursing Science.

  5. Long-term results of Gamma-knife stereotactic radiosurgery for vestibular schwannomas in patients with type 2 neurofibromatosis.

    PubMed

    Spatola, G; Carron, R; Delsanti, C; Thomassin, J-M; Roche, P-H; Régis, J

    2016-08-12

    The aim of this study was to analyze the long-term results of Gamma-knife radiosurgery treatment of vestibular schwannomas in type 2 neurofibromatosis patients. A cohort of 129 treatments for vestibular schwannomas in 103 patients was selected from a prospectively-maintained clinical database. Tumor control was assessed by volumetric analysis of the tumor at the last follow-up. Any need of a further procedure such as microsurgical removal or second treatment was regarded as a failure of tumor control. Hearing function was assessed based on Gardner-Robertson classification. Progression-free survival and functional hearing preservation rates were estimated using the Kaplan-Meier method. The median age at treatment was 34 years with no gender predominance. The median tumor volume was 1.5cm 3 . At a median clinical follow-up of 5.9 years, five patients had died, four underwent a second radiosurgical procedure and eight underwent microsurgical resection. Progression-free survival was 88 and 75% respectively at 5 and 10 years. Hearing was considered serviceable in 70 ears and remained functional in 28 ears. Kaplan-Meier estimates for 5 and 10 years functional hearing was 47 and 34%, respectively. Three patients developed new facial nerve palsy after radiosurgery at 15 days, 6 and 19 months respectively and only one partially recovered. Five patients complained of a subjective instability worsening. Four cases developed trigeminal neuropathy. No predictive factors were found to be statistically correlated with a better hearing outcome or an improved tumor growth control. Results prove less satisfying than in sporadic unilateral schwannomas. However, the lower rate of mortality and morbidity compared with microsurgical resection may support a proactive role of Gamma-knife in this pathology. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  6. Ingenious laparoscopic knife.

    PubMed

    Goel, Rajiv; Modi, Pranjal

    2007-06-01

    Retroperitoneoscopic ureterolithotomy may be an option in selected group of patients. We present our cost effective, reliable ingenious laparoscopic knife of ureteric incision during retroperitoneoscopic ureterolithotomy. Ingenious laparoscopic knife is made by firmly tying stab knife to 5 mm laparoscopic instrument. This knife is passed through 10-mm renal angle port for making ureteric incision. Ingenious laparoscopic knife has been successfully used in 22 patients with no intraoperative and postoperative complications. Ingenious laparoscopic knife is cost effective, reliable instrument for ureteric incision during retroperitoneoscopic ureterolithotomy.

  7. Positive clinical effects of gamma knife capsulotomy in a patient with deep brain stimulation-refractory Tourette Syndrome and Obsessive Compulsive Disorder.

    PubMed

    Richieri, Raphaëlle; Blackman, Graham; Musil, Richard; Spatola, Giorgio; Cavanna, Andrea E; Lançon, Christophe; Régis, Jean

    2018-04-26

    We report the first case of a patient with severe, intractable Tourette Syndrome with comorbid Obsessive Compulsive disorder, who recovered from both disorders with gamma-knife (GK) stereotactic radiosurgery following deep brain stimulation (DBS). This case highlights the possible role of the internal capsule within the neural circuitries underlying both TS and OCD, and suggests that in cases of treatment-refractory TS and comorbid OCD, bilateral anterior capsulotomy using stereotactic radiosurgery may be a viable treatment option. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Clinical features of brain metastases from hepatocellular carcinoma using gamma knife surgery.

    PubMed

    Ogino, Akiyoshi; Hirai, Tatsuo; Serizawa, Toru; Yoshino, Atsuo

    2018-05-01

    Brain metastases from hepatocellular carcinoma (HCC) are rare, but their incidence is increasing because of developments in recent therapeutic advances. The purpose of this study was to investigate the characteristics of brain metastases from HCC, to evaluate the predictive factors, and to assess the efficacy of gamma knife surgery (GKS). A retrospective study was performed on patients with brain metastases from HCC who were treated at Tokyo Gamma Unit Center from 2005 to 2014. Nineteen patients were identified. The median age at diagnosis of brain metastases was 67.0 years. Fifteen patients were male and four patients were female. Six patients were infected with hepatitis B virus (HBV). Two patients were infected with hepatitis C virus (HCV). Eleven patients were not infected with HBV or HCV. The median interval from the diagnosis of HCC to brain metastases was 32.0 months. The median number of brain metastases was two. The median Karnofsky performance score at first GKS was 70. The median survival time following brain metastases was 21.0 weeks. Six-month and 1-year survival rates were 41.2 and 0%, respectively. One month after GKS, no tumor showed progressive disease. The HBV infection (positive vs. negative) was significantly associated with survival according to univariate analysis (p = 0.002). The patients having brain metastases from HCC had poor prognosis and low performance state. Therefore, GKS is an acceptable option for controlling brain metastases from HCC because GKS is noninvasive remedy and local control is reasonable.

  9. Gamma Knife Radiosurgery for Pediatric Arteriovenous Malformations: A Canadian Experience.

    PubMed

    Zeiler, Fred A; Janik, Maciej K; McDonald, Patrick J; Kaufmann, Anthony M; Fewer, Derek; Butler, Jim; Schroeder, Garry; West, Michael

    2016-01-01

    Gamma Knife (GK) radiosurgery for pediatric arteriovenous malformations (AVM) of the brain presents a non-invasive treatment option. We report our institutional experience with GK for pediatric AVMs. We performed a retrospective review of all pediatric patients treated with GK for cerebral AVMs at our institution from November 2003 up to and including September 2014. Patient demographics, AVM characteristics, treatment parameters and AVM responses were recorded. Nineteen patients were treated, with 4 lost to follow-up. The mean age was 14.2 years (range. 7-18 years), with 10 being males (52.6%). The mean AVM diameter and volume were 2.68 cm and 3.10 cm3 respectively. The mean Spetzler-Martin (SM) and Pollock grades of the treated AVMs were 2.4 and 0.99 respectively. The mean follow-up was 62 months. All AVMs treated demonstrated a response on follow-up imaging. Nine of 15 (60.0%) patients displayed obliteration of their AVMs. Nine of 11 patients with a minimum of 3 years follow-up (81.8%) displayed obliteration, with SM and Pollock grades correlating to the chance of obliteration in this group. Two patients developed post-GK edema requiring short course dexamethasone therapy. No other major complications occurred. No permanent complications occurred. GK radiosurgery for pediatric AVMs offers a safe and effective treatment option, with low permanent complication rates during early follow-up.

  10. Long-Term Survival after Gamma Knife Radiosurgery in a Case of Recurrent Glioblastoma Multiforme: A Case Report and Review of the Literature

    PubMed Central

    Thumma, Sudheer R.; Elaimy, Ameer L.; Daines, Nathan; Mackay, Alexander R.; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Demakas, John J.; Cooke, Barton S.; Lee, Christopher M.

    2012-01-01

    The management of recurrent glioblastoma is highly challenging, and treatment outcomes remain uniformly poor. Glioblastoma is a highly infiltrative tumor, and complete surgical resection of all microscopic extensions cannot be achieved at the time of initial diagnosis, and hence local recurrence is observed in most patients. Gamma Knife radiosurgery has been used to treat these tumor recurrences for select cases and has been successful in prolonging the median survival by 8–12 months on average for select cases. We present the unique case of a 63-year-old male with multiple sequential recurrences of glioblastoma after initial standard treatment with surgery followed by concomitant external beam radiation therapy and chemotherapy (temozolomide). The patient was followed clinically as well as with surveillance MRI scans at every 2-3-month intervals. The patient underwent Gamma Knife radiosurgery three times for 3 separate tumor recurrences, and the patient survived for seven years following the initial diagnosis with this aggressive treatment. The median survival in patients with recurrent glioblastoma is usually 8–12 months after recurrence, and this unique case illustrates that aggressive local therapy can lead to long-term survivors in select situations. We advocate that each patient treatment at the time of recurrence should be tailored to each clinical situation and desire for quality of life and improved longevity. PMID:22548078

  11. Advanced image fusion algorithms for Gamma Knife treatment planning. Evaluation and proposal for clinical use.

    PubMed

    Apostolou, N; Papazoglou, Th; Koutsouris, D

    2006-01-01

    Image fusion is a process of combining information from multiple sensors. It is a useful tool implemented in the treatment planning programme of Gamma Knife Radiosurgery. In this paper we evaluate advanced image fusion algorithms for Matlab platform and head images. We develop nine level grayscale image fusion methods: average, principal component analysis (PCA), discrete wavelet transform (DWT) and Laplacian, filter - subtract - decimate (FSD), contrast, gradient, morphological pyramid and a shift invariant discrete wavelet transform (SIDWT) method in Matlab platform. We test these methods qualitatively and quantitatively. The quantitative criteria we use are the Root Mean Square Error (RMSE), the Mutual Information (MI), the Standard Deviation (STD), the Entropy (H), the Difference Entropy (DH) and the Cross Entropy (CEN). The qualitative are: natural appearance, brilliance contrast, presence of complementary features and enhancement of common features. Finally we make clinically useful suggestions.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Han, Jung Ho; Kim, Dong Gyu, E-mail: gknife@plaza.snu.ac.k; Chung, Hyun-Tai

    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 weremore » 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.« less

  13. Equivalence in Dose Fall-Off for Isocentric and Nonisocentric Intracranial Treatment Modalities and Its Impact on Dose Fractionation Schemes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ma Lijun, E-mail: lijunma@radonc.ucsf.ed; Sahgal, Arjun; Descovich, Martina

    2010-03-01

    Purpose: To investigate whether dose fall-off characteristics would be significantly different among intracranial radiosurgery modalities and the influence of these characteristics on fractionation schemes in terms of normal tissue sparing. Methods and Materials: An analytic model was developed to measure dose fall-off characteristics near the target independent of treatment modalities. Variations in the peripheral dose fall-off characteristics were then examined and compared for intracranial tumors treated with Gamma Knife, Cyberknife, or Novalis LINAC-based system. Equivalent uniform biologic effective dose (EUBED) for the normal brain tissue was calculated. Functional dependence of the normal brain EUBED on varying numbers of fractions (1more » to 30) was studied for the three modalities. Results: The derived model fitted remarkably well for all the cases (R{sup 2} > 0.99). No statistically significant differences in the dose fall-off relationships were found between the three modalities. Based on the extent of variations in the dose fall-off curves, normal brain EUBED was found to decrease with increasing number of fractions for the targets, with alpha/beta ranging from 10 to 20. This decrease was most pronounced for hypofractionated treatments with fewer than 10 fractions. Additionally, EUBED was found to increase slightly with increasing number of fractions for targets with alpha/beta ranging from 2 to 5. Conclusion: Nearly identical dose fall-off characteristics were found for the Gamma Knife, Cyberknife, and Novalis systems. Based on EUBED calculations, normal brain sparing was found to favor hypofractionated treatments for fast-growing tumors with alpha/beta ranging from 10 to 20 and single fraction treatment for abnormal tissues with low alpha/beta values such as alpha/beta = 2.« less

  14. Dosimetric comparison between cone/Iris-based and InCise MLC-based CyberKnife plans for single and multiple brain metastases.

    PubMed

    Jang, Si Young; Lalonde, Ron; Ozhasoglu, Cihat; Burton, Steven; Heron, Dwight; Huq, M Saiful

    2016-09-08

    We performed an evaluation of the CyberKnife InCise MLC by comparing plan qualities for single and multiple brain lesions generated using the first version of InCise MLC, fixed cone, and Iris collimators. We also investigated differences in delivery efficiency among the three collimators. Twenty-four patients with single or multiple brain mets treated previously in our clinic on a CyberKnife M6 using cone/Iris collimators were selected for this study. Treatment plans were generated for all lesions using the InCise MLC. Number of monitor units, delivery time, target coverage, conformity index, and dose falloff were compared between MLC- and clinical cone/Iris-based plans. Statistical analysis was performed using the non-parametric Wilcoxon-Mann-Whitney signed-rank test. The planning accuracy of the MLC-based plans was validated using chamber and film measurements. The InCise MLC-based plans achieved mean dose and target coverage comparable to the cone/Iris-based plans. Although the conformity indices of the MLC-based plans were slightly higher than those of the cone/Iris-based plans, beam delivery time for the MLC-based plans was shorter by 30% ~ 40%. For smaller targets or cases with OARs located close to or abutting target volumes, MLC-based plans provided inferior dose conformity compared to cone/Iris-based plans. The QA results of MLC-based plans were within 5% absolute dose difference with over 90% gamma passing rate using 2%/2 mm gamma criteria. The first version of InCise MLC could be a useful delivery modality, especially for clinical situations for which delivery time is a limiting factor or for multitarget cases. © 2016 The Authors.

  15. Gamma knife radiosurgery for skull-base meningiomas.

    PubMed

    Takanashi, Masami; Fukuoka, Seiji; Hojyo, Atsufumi; Sasaki, Takehiko; Nakagawara, Jyoji; Nakamura, Hirohiko

    2009-01-01

    The primary purpose of this study was to evaluate the efficacy of gamma knife radiosurgery (GKRS) when used as a treatment modality for cavernous sinus or posterior fossa skull-base meningiomas (SBMs), with particular attention given to whether or not intentional partial resection followed by GKRS constitutes an appropriate combination treatment method for larger SBMs. Of the 101 SBM patients in this series, 38 were classified as having cavernous sinus meningiomas (CSMs), and 63 presented with posterior fossa meningiomas (PFMs). The patients with no history of prior surgery (19 CSMs, 57 PFMs) were treated according to a set protocol. Small to medium-sized SBMs were treated by GKRS only. To minimize the risk of functional deficits, larger tumors were treated with the combination of intentional partial resection followed by GKRS. Residual or recurrent tumors in patients who had undergone extirpations prior to GKRS (19 CSMs, 6 PFMs) are not eligible for this treatment method (due to the surgeries not being performed as part of a combination strategy designed to preserve neurological function as the first priority). The mean follow-up period was 51.9 months (range, 6-144 months). The overall tumor control rates were 95.5% in CSMs and 98.4% in PFMs. Nearly all tumors treated with GKRS alone were well controlled and the patients had no deficits. Furthermore, none of the patients who had undergone prior surgeries experienced new neurological deficits after GKRS. While new neurological deficits appeared far less often in those receiving the combination of partial resection with subsequent GKRS, extirpations tended to be associated with not only a higher incidence of new deficits but also a significant increase in the worsening of already-existing deficits. Our results indicate that GKRS is a safe and effective primary treatment for SBMs with small to moderate tumor volumes. We also found that larger SBMs compressing the optic pathway or brain stem can be effectively

  16. Exposure of luminous marine bacteria to low-dose gamma-radiation.

    PubMed

    Kudryasheva, N S; Petrova, A S; Dementyev, D V; Bondar, A A

    2017-04-01

    The study addresses biological effects of low-dose gamma-radiation. Radioactive 137 Cs-containing particles were used as model sources of gamma-radiation. Luminous marine bacterium Photobacterium phosphoreum was used as a bioassay with the bioluminescent intensity as the physiological parameter tested. To investigate the sensitivity of the bacteria to the low-dose gamma-radiation exposure (≤250 mGy), the irradiation conditions were varied as follows: bioluminescence intensity was measured at 5, 10, and 20°С for 175, 100, and 47 h, respectively, at different dose rates (up to 4100 μGy/h). There was no noticeable effect of gamma-radiation at 5 and 10°С, while the 20°С exposure revealed authentic bioluminescence inhibition. The 20°С results of gamma-radiation exposure were compared to those for low-dose alpha- and beta-radiation exposures studied previously under comparable experimental conditions. In contrast to ionizing radiation of alpha and beta types, gamma-emission did not initiate bacterial bioluminescence activation (adaptive response). As with alpha- and beta-radiation, gamma-emission did not demonstrate monotonic dose-effect dependencies; the bioluminescence inhibition efficiency was found to be related to the exposure time, while no dose rate dependence was found. The sequence analysis of 16S ribosomal RNA gene did not reveal a mutagenic effect of low-dose gamma radiation. The exposure time that caused 50% bioluminescence inhibition was suggested as a test parameter for radiotoxicity evaluation under conditions of chronic low-dose gamma irradiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Repeated transsphenoidal surgery or gamma knife radiosurgery in recurrent cushing disease after transsphenoidal surgery.

    PubMed

    Bodaghabadi, Mohammad; Riazi, Hooman; Aran, Shima; Bitaraf, Mohammad Ali; Alikhani, Mazdak; Alahverdi, Mahmud; Mohamadi, Masoumeh; Shalileh, Keivan; Azar, Maziar

    2014-03-01

    This study compared Gamma knife radiosurgery (GKRS) and repeated transsphenoidal adenomectomy (TSA) to find the best approach for recurrence of Cushing disease (CD) after unsuccessful first TSA. Fifty-two patients with relapse of CD after TSA were enrolled and randomly underwent a second surgery or GKRS as the next therapeutic approach. They were followed for a mean period of 3.05 ± 0.8 years by physical examination and hormone measurement as well as magnetic resonance imaging. No significant difference was observed in sex ratio, mean age, adenoma type, follow-up duration, and initial hormone level between the two groups. No significant relationship was found between preoperative 24-hour free urine cortisol and disease-free months or tumor volume among both groups. Our statistical analysis showed higher recurrence-free interval in the GKRS group compared with TSA group. With longer recurrence-free interval, GKRS could be considered a good treatment alternative to repeated TSA in recurrent CD. Georg Thieme Verlag KG Stuttgart · New York.

  18. Gamma knife radiosurgery for medically and surgically refractory prolactinomas.

    PubMed

    Pouratian, Nader; Sheehan, Jason; Jagannathan, Jay; Laws, Edward R; Steiner, Ladislau; Vance, Mary L

    2006-08-01

    Experience with gamma knife radiosurgery (GKRS) for prolactinomas is limited because of the efficacy of medical and surgical intervention. Patients who are refractory to medical and/or surgical therapy may be treated with GKRS. We characterize the efficacy of GKRS for medically and surgically refractory prolactinomas. We reviewed our series of patients with prolactinomas who were treated with GKRS after failing medical and surgical intervention who had at least 1 year of follow-up. Twenty-three patients were included in analysis of endocrine outcomes (median and average follow-up of 55 and 58 mo, respectively) and 28 patients were included in analysis of imaging outcomes (median and average follow-up of 48 and 52 mo, respectively). Twenty-six percent of patients achieved a normal serum prolactin (remission) with an average time of 24.5 months. Remission was significantly associated with being off of a dopamine agonist at the time of GKRS and a tumor volume less than 3.0 cm3 (P < 0.05 for both). Long-term image-based volumetric control was achieved in 89% of patients. Complications included new pituitary hormone deficiencies in 28% of patients and cranial nerve palsy in two patients (7%). Clinical remission in 26% of treated patients is a modest result. However, because the GKRS treated tumors were refractory to other therapies and because complication rates were low, GKRS should be part of the armamentarium for treating refractory prolactinomas. Patients with tumors smaller than 3.0 cm3 and who are not receiving dopamine agonist at the time of treatment will likely benefit most.

  19. Gamma Knife radiosurgery for hypothalamic hamartoma preserves endocrine functions.

    PubMed

    Castinetti, Frederic; Brue, Thierry; Morange, Isabelle; Carron, Romain; Régis, Jean

    2017-06-01

    Gamma Knife radiosurgery (GK) is an effective treatment for hypothalamic hamartoma. No precise data are available on the risk of endocrine side effects of this treatment. In this study, 34 patients with hypothalamic hamartoma (HH) were followed prospectively at the Department of Endocrinology, La Timone Hospital, Marseille, France, for a mean follow-up of >2 years (mean ± standard deviation [SD] 3.6 ± 2 years). Initial pre- and post-GK radiosurgery evaluations were performed, including weight, body mass index (BMI), and a complete endocrinological workup. At diagnosis, eight patients presented with central precocious puberty at a mean age of 5.4 ± 2.4 years. At the time of GK (mean age 18.2 ± 11.1 years), two patients previously treated with surgery presented with luteinizing hormone/follicle-stimulating hormone (LH/FSH) deficiency. After GK, only one patient presented with a new thyrotropin-stimulating hormone (TSH) deficiency, 2 years after the procedure. The other pituitary axes remained normal in all but two patients (who had LH/FSH deficiency prior to GK). There was no significant difference between pre- and post-GK mean BMI (26.9 vs. 25.1 kg/m 2 , p = 0.59). To conclude, in this group of 34 patients, GK did not induce major endocrinologic side effects reported with all the other surgical techniques in the literature. It is, thus, a safe and effective procedure in the treatment of hypothalamic hamartoma. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Karaiskos, Pantelis, E-mail: pkaraisk@med.uoa.gr; Gamma Knife Department, Hygeia Hospital, Athens; Moutsatsos, Argyris

    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 acquiredmore » 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.« less

  1. Histopathological observations on vestibular schwannomas after Gamma Knife radiosurgery: the Marseille experience.

    PubMed

    Szeifert, G T; Figarella-Branger, D; Roche, P-H; Régis, J

    2004-06-01

    Radiosurgery has become a successful treatment modality in the management of vestibular schwannomas (VS) during the past four decades. Although the number of treated cases has been increasing continuously we know relatively little about the pathological effect of high dose irradiation on VS following radiosurgery. The purpose of this study was to analyze histopathological changes in VS after Leksell Gamma Knife (LGK) radiosurgery. Out of a series of 1350 VS cases treated with LGK surgery 22 patients underwent craniotomy for tumor removal in 6-92 Months interval after radiosurgery. Surgical pathology material was available in 17 cases. Routine histological and immunohistochemical investigations were performed on the tIssue samples. Histopathological findings were compared with clinical and radiological follow-up data. Coagulation necrosis in the central part of the schwannomas surrounded with a transitional zone containing loosened tIssue structure of shrunken tumor cells covered with an outer capsule of vigorous neoplastic cells was the basic histopathological lesion. Granulation tIssue proliferation with inflammatory cell infiltration, different extent of hemorrhages and scar tIssue development was usually present. Endothelial destruction or wall damage of vascular channels was a common finding. Analyzing the follow-up data it turned out that 7 patients out of the 22 were operated on because of radiological progression only without clinical deterioration and 4 of them was removed during the latency period after radiosurgery. Results of the present histopathological study suggest that radiosurgery works with double effect on VS: it seems to destroy directly tumor cells (with necrosis or inducing apoptosis), and causes vascular damages as well. The loss of central contrast enhancement on CT and MR images following radiosurgery might be consequence of necrosis and vascular impairment. From clinical-pathological point of view we think that patients should not undergo

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Keeling, V; Algan, O; Ahmad, 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-coplanarmore » 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.« less

  3. Relapsed or refractory primary central nervous system lymphoma radiosurgery: Report of the International Gamma Knife Research Foundation.

    PubMed

    Shin, Samuel M; Silverman, Joshua S; Bowden, Greg; Mathieu, David; Yang, Huai-Che; Lee, Cheng-Chia; Tam, Moses; Szelemej, Paul; Kaufmann, Anthony M; Cohen-Inbar, Or; Sheehan, Jason; Niranjan, Ajay; Lunsford, L Dade; Kondziolka, Douglas

    2017-01-01

    Stereotactic radiosurgery (SRS) can be used as part of multimodality management for patients with primary central nervous system lymphoma (PCNSL). The objective of this study is to evaluate outcomes of SRS for this disease. The International Gamma Knife Research Foundation identified 23 PCNSL patients who underwent SRS for either relapsed (intracerebral in-field or out-of-field tumor recurrences) or refractory disease from 1995-2014. All 23 patients presented with RPA Class I or II PCNSL, and were initially treated with a median of 7 cycles of methotrexate-based chemotherapy regimens (range, 3-26 cycles). Ten received prior whole brain radiation (WBRT) to a median dose of 43 Gy (range, 24-55 Gy). Sixteen presented with relapsed PCNSL, and seven presented with refractory disease. Twenty-three received 26 procedures of SRS. The median tumor volume was 4 cm 3 (range, 0.1-26 cm 3 ), and the median margin dose was 15 Gy (range, 8-20 Gy). Median follow-up from SRS was 11 months (interquartile range, 5.7-33.2 months). Twenty presented with treatment response to twenty-three tumors (12 complete, 11 partial). Fourteen patients relapsed or were refractory to salvage SRS, and local control was 95%, 91%, and 75% at 3, 6, and 12 months post SRS. Intracranial (in-field and out-of-field) and distant (systemic) PFS was 86%, 81%, and 55% at 3, 6, and 12 months post SRS. Toxicity of SRS was low, with one developing an adverse radiation effect requiring no additional intervention. Although methotrexate-based chemotherapy regimens with or without WBRT is the first-line management option for PCNSL, SRS may be used as an alternative option in properly selected patients with smaller relapsed or refractory PCNSL tumors.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, Haksoo; Welford, Scott; Fabien, Jeffrey

    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, withmore » 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

  5. P13.17STEREOTACTIC RADIOSURGERY WITH GAMMA KNIFE FOR NEUROFIBROMATOSIS 2-ASSOCIATED VESTIBULAR SCHWANNOMAS

    PubMed Central

    Presti, A. Lo; De Andrés, P.; Kusak, M.E.; De Campos, J.M.; Martínez, N.; Martínez, R.

    2014-01-01

    BACKGROUND: It is though that Stereotactic Radiosurgery (SRS) is less effective in achieving local tumor control in Neurofibromatosis 2 (NF2)-related vestibular schwannomas (VSs) compared with sporadic tumors. There is scarce literature on optimal dosing, clinical outcomes and eventual increased risk for malignant transformation among these patients. It is also possible that radiation induced tumors, in patients bearing an abnormality in a tumor suppressor gene, are misinterpreted as part of the natural history of NF2, where new tumors are expected to develop. OBJECTIVE: To evaluate the results of Gamma Knife (GK) Radiosurgery in the management of NF2-related VSs versus the sporadic VSs group treated at the same Center. METHOD: A prospectively maintained clinical database including all patients who underwent SRS for VSs was reviewed, and all subjects fulfilling the Manchester diagnostic criteria for NF2 were identified. Between 1994 and 2012, 35 patients with NF2 underwent SRS for 55 presumed VSs at our institution. The mean age at time of treatment was 30.8 years and the mean follow-up period was 4.3 years (1-14.75 years). The median margin dose used was 12 Gy and a total of 62 treatments were performed. Outcome measures, including imaging progression, hearing preservation, trigeminal and facial nerve function, were analyzed. RESULTS: Regarding tumor control 53.4% remained unchanged in size, 22.4% were smaller and 22.4% showed progression requiring further microsurgical resection or SRS. Hearing worsening occurred in 37% of tumors; 2 patients developed facial neuropathy, one of them bilateral and the other transient; trigeminal neuropathy occurred in 4 patients, one of them with previous mild impairment. No cases of malignant transformation were reported. Compared to the sporadic VSs group, NF2 patients showed lower local tumor control and higher incidence of facial and trigeminal neuropathy. CONCLUSION: NF2-related VSs treated with GK show worse clinical and

  6. SU-E-T-213: Comparison of Treatment Efficiency of Gamma Knife SRS Plans for Brain Metastases with Different Planning Methods

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Y; Huang, Z; Lo, S

    2015-06-15

    Purpose: To improve Gamma Knife SRS treatment efficiency for brain metastases and compare the differences of treatment time and radiobiological effects between two different planning methods of automatic filling and manual placement of shots with inverse planning. Methods: T1-weighted MRI images with gadolinium contrast from five patients with a single brain metastatic-lesion were used in this retrospective study. Among them, two were from primary breast cancer, two from primary melanoma cancer and one from primary prostate cancer. For each patient, two plans were generated in Leksell GammaPlan10.1.1 for radiosurgical treatment with a Leksell GammaKnife Perfexion machine: one with automatic filling,more » automatic sector configuration and inverse optimization (Method1); and the other with manual placement of shots, manual setup of collimator sizes, manual setup of sector blocking and inverse optimization (Method2). Dosimetric quality of the plans was evaluated with parameters of Coverage, Selectivity, Gradient-Index and DVH. Beam-on Time, Number-of-Shots and Tumor Control Probability(TCP) were compared for the two plans while keeping their dosimetric quality very similar. Relative reduction of Beam-on Time and Number-of-Shots were calculated as the ratios among the two plans and used for quantitative analysis. Results: With very similar dosimetric and radiobiological plan quality, plans created with Method 2 had significantly reduced treatment time. Relative reduction of Beam-on Time ranged from 20% to 51 % (median:29%,p=0.001), and reduction of Number-of-Shots ranged from 5% to 67% (median:40%,p=0.0002), respectively. Time of plan creation for Method1 and Method2 was similar, approximately 20 minutes, excluding the time for tumor delineation. TCP calculated for the tumors from differential DVHs did not show significant difference between the two plans (p=0.35). Conclusion: The method of manual setup combined with inverse optimization in LGP for treatment of

  7. Analysis of risk factors to predict communicating hydrocephalus following gamma knife radiosurgery for intracranial schwannoma.

    PubMed

    Lee, Seunghoon; Seo, Seong-Wook; Hwang, Juyoung; Seol, Ho Jun; Nam, Do-Hyun; Lee, Jung-Il; Kong, Doo-Sik

    2016-12-01

    Communicating hydrocephalus (HCP) in vestibular schwannomas (VS) after gamma knife radiosurgery (GKRS) has been reported in the literature. However, little information about its incidence and risk factors after GKRS for intracranial schwannomas is yet available. The objective of this study was to identify the incidence and risk factors for developing communicating HCP after GKRS for intracranial schwannomas. We retrospectively reviewed a total of 702 patients with intracranial schwannomas who were treated with GKRS between January 2002 and December 2015. We investigated patients' age, gender, tumor origin, previous surgery history, tumor volume, marginal radiation dose, and presence of tumor control to identify associations with communicating HCP following GKRS. To make predictive models of communicating HCP, we performed Cox regression analyses and constructed a decision tree for risk factors. In total, 29 of the 702 patients (4.1%) developed communicating HCP following GKRS, which required ventriculo-peritoneal (VP) shunt surgery. Multivariate analyses indicated that age (P = 0.0011), tumor origin (P = 0.0438), and tumor volume (P < 0.0001) were significant predictors of communicating HCP in patients with intracranial schwannoma after GKRS. Using machine-learning methods, we fit an optimal predictive model. We found that developing communicating HCP following GKRS was most likely if the tumor was vestibular origin and had a volume ≥13.65 cm 3 . Communicating HCP is not a rare complication of GKRS for intracranial schwannomas. Under specific conditions, communicating HCP following GKRS is warranted for this patient group, and this patient group should be closely followed up. © 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

  8. Gamma Knife radiosurgery for posterior fossa meningiomas: a multicenter study.

    PubMed

    Sheehan, Jason P; Starke, Robert M; Kano, Hideyuki; Barnett, Gene H; Mathieu, David; Chiang, Veronica; Yu, James B; Hess, Judith; McBride, Heyoung L; Honea, Norissa; Nakaji, Peter; Lee, John Y K; Rahmathulla, Gazanfar; Evanoff, Wendi A; Alonso-Basanta, Michelle; Lunsford, L Dade

    2015-06-01

    Posterior fossa meningiomas represent a common yet challenging clinical entity. They are often associated with neurovascular structures and adjacent to the brainstem. Resection can be undertaken for posterior fossa meningiomas, but residual or recurrent tumor is frequent. Stereotactic radiosurgery (SRS) has been used to treat meningiomas, and this study evaluates the outcome of this approach for those located in the posterior fossa. At 7 medical centers participating in the North American Gamma Knife Consortium, 675 patients undergoing SRS for a posterior fossa meningioma were identified, and clinical and radiological data were obtained for these cases. Females outnumbered males at a ratio of 3.8 to 1, and the median patient age was 57.6 years (range 12-89 years). Prior resection was performed in 43.3% of the patient sample. The mean tumor volume was 6.5 cm(3), and a median margin dose of 13.6 Gy (range 8-40 Gy) was delivered to the tumor. At a mean follow-up of 60.1 months, tumor control was achieved in 91.2% of cases. Actuarial tumor control was 95%, 92%, and 81% at 3, 5, and 10 years after radiosurgery. Factors predictive of tumor progression included age greater than 65 years (hazard ratio [HR] 2.36, 95% CI 1.30-4.29, p = 0.005), prior history of radiotherapy (HR 5.19, 95% CI 1.69-15.94, p = 0.004), and increasing tumor volume (HR 1.05, 95% CI 1.01-1.08, p = 0.005). Clinical stability or improvement was achieved in 92.3% of patients. Increasing tumor volume (odds ratio [OR] 1.06, 95% CI 1.01-1.10, p = 0.009) and clival, petrous, or cerebellopontine angle location as compared with petroclival, tentorial, and foramen magnum location (OR 1.95, 95% CI 1.05-3.65, p = 0.036) were predictive of neurological decline after radiosurgery. After radiosurgery, ventriculoperitoneal shunt placement, resection, and radiation therapy were performed in 1.6%, 3.6%, and 1.5%, respectively. Stereotactic radiosurgery affords a high rate of tumor control and neurological preservation

  9. Five-year Survival After Surgical Removal and Gamma Knife Stereotactic Radiosurgery for a Cerebellar Metastasis from an Esophagogastric Junction Cancer: A Case Report and Literature Review

    PubMed Central

    KANAZAWA, YOSHIKAZU; FUJITA, ITSUO; KAKINUMA, DAISUKE; AOKI, YUTO; KANNO, HITOSHI; ARAI, HIROKI; MATSUNO, KUNIHIKO; SHIMODA, TOMOHIRO; MATSUTANI, TAKESHI; HAGIWARA, NOBUTOSHI; NOMURA, TSUTOMU; YAMADA, TAKESHI; KATO, SHUNJI; NAITO, ZENYA; TAKASAKI, HIDEAKI; UCHIDA, EIJI

    2017-01-01

    Brain metastases originating from esophageal or gastric cancer are rare, accounting for 2.1-3.3% of all brain tumors registered in Japan. There are no established therapeutic measures for brain metastases, which accordingly have a poor prognosis. We present here a patient who survived for 5 years after surgery and gamma knife treatment of a cerebellar metastasis from esophagogastric adenocarcinoma. The primary gastric cancer was treated by laparotomy with total gastrectomy, splenectomy, and D2 lymphadenectomy. It was diagnosed as a esophagogastric junction Siewert type II tumor, type 3, tub1-2, pT3 (SS), pN1, and stage IIB on histopathological examination of the surgical specimen. Five months postoperatively, a solitary cerebellar metastasis was identified and surgically removed, followed by 20 Gy administered by gamma knife stereotactic radiosurgery; the patient received no subsequent treatment such as chemotherapy. Five years after the primary surgery, there have been no recurrences and the patient has a good quality of life. There are very few case reports of long-term survival after surgical treatment of cerebellar metastases from esophagogastric junction cancer. We report our experience and review published case reports of surgical treatment of brain metastases from gastric cancer. PMID:29102948

  10. Gamma Knife radiosurgery for vestibular schwannoma: case report and review of the literature.

    PubMed

    Arthurs, Benjamin J; Lamoreaux, Wayne T; Giddings, Neil A; Fairbanks, Robert K; Mackay, Alexander R; Demakas, John J; Cooke, Barton S; Lee, Christopher M

    2009-12-18

    Vestibular schwannomas, also called acoustic neuromas, are benign tumors of the vestibulocochlear nerve. Patients with these tumours almost always present with signs of hearing loss, and many also experience tinnitus, vertigo, and equilibrium problems. Following diagnosis with contrast enhanced MRI, patients may choose to observe the tumour with subsequent scans or seek active treatment in the form of microsurgery, radiosurgery, or radiotherapy. Unfortunately, definitive guidelines for treating vestibular schwannomas are lacking, because of insufficient evidence comparing the outcomes of therapeutic modalities.We present a contemporary case report, describing the finding of a vestibular schwannoma in a patient who presented with dizziness and a "clicking" sensation in the ear, but no hearing deficit. Audible clicking is a symptom that, to our knowledge, has not been associated with vestibular schwannoma in the literature. We discuss the diagnosis and patient's decision-making process, which led to treatment with Gamma Knife radiosurgery. Treatment resulted in an excellent radiographic response and complete hearing preservation. This case highlights an atypical presentation of vestibular schwannoma, associated with audible "clicks" and normal hearing. We also provide a concise review of the available literature on modern vestibular schwannoma treatment, which may be useful in guiding treatment decisions.

  11. beta- and gamma-Comparative dose estimates on Enewetak Atoll.

    PubMed

    Crase, K W; Gudiksen, P H; Robison, W L

    1982-05-01

    Enewetak Atoll is one of the Pacific atolls used for atmospheric testing of U.S. nuclear weapons. Beta dose and gamma-ray exposure measurements were made on two islands of the Enewetak Atoll during July-August 1976 to determine the beta and low energy gamma-contribution to the total external radiation doses to the returning Marshallese. Measurements were made at numerous locations with thermoluminescent dosimeters (TLD), pressurized ionization chambers, portable NaI detectors, and thin-window pancake GM probes. Results of the TLD measurements with and without a beta-attenuator indicate that approx. 29% of the total dose rate at 1 m in air is due to beta- or low energy gamma-contribution. The contribution at any particular site, however, is somewhat dependent on ground cover, since a minimal amount of vegetation will reduce it significantly from that over bare soil, but thick stands of vegetation have little effect on any further reductions. Integral 30-yr external shallow dose estimates for future inhabitants were made and compared with external dose estimates of a previous large scale radiological survey (En73). Integral 30-yr shallow external dose estimates are 25-50% higher than whole body estimates. Due to the low penetrating ability of the beta's or low energy gamma's, however, several remedial actions can be taken to reduce the shallow dose contribution to the total external dose.

  12. Application of the concept of biologically effective dose (BED) to patients with Vestibular Schwannomas treated by radiosurgery

    PubMed Central

    Millar, William T.; Lindquist, Christer; Nordström, Håkan; Lidberg, Pär; Gårding, Jonas

    2013-01-01

    In the application of stereotactic radiosurgery, using the Gamma Knife, there are large variations in the overall treatment time for the same prescription dose, given in a single treatment session, for different patients. This is due to not only changes in the activity of the Cobolt-60 sources, but also to variations in the number of iso-centers used, the collimator size for a particular iso-center, and the time gap between the different iso-centers. Although frequently viewed as a single dose treatment the concept of biologically effective dose (BED), incorporating concurrent fast and a slow components of repair of sublethal damage, would imply potential variations in BED because of the influence of these different variables associated with treatment. This was investigated in 26 patients, treated for Vestibular Schwannomas, using the Series B Gamma-Knife, between 1999 and 2005. The iso-center number varied between 2 and 13, and the overall treatment time from 25.4–129.58 min. The prescription doses varied from 10–14 Gy. To obtain physical dose and dose-rates from each iso-center, in a number of locations in the region of interest, a prototype version of the Leksell GammaPlan® was used. For an individual patient, BED values varied by up to 15% for a given physical iso-dose. This was due to variation in the dose prescription at different locations on that iso-dose. Between patients there was a decline in the range of BED values as the overall treatment time increased. This increased treatment time was partly a function of the slow decline in the activity of the sources with time but predominantly due to changes in the number of iso-centers used. Thus, variations in BED values did not correlate with prescription dose but was modified by the overall treatment time. PMID:29296371

  13. Novel Radiobiological Gamma Index for Evaluation of 3-Dimensional Predicted Dose Distribution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sumida, Iori, E-mail: sumida@radonc.med.osaka-u.ac.jp; Yamaguchi, Hajime; Kizaki, Hisao

    2015-07-15

    Purpose: To propose a gamma index-based dose evaluation index that integrates the radiobiological parameters of tumor control (TCP) and normal tissue complication probabilities (NTCP). Methods and Materials: Fifteen prostate and head and neck (H&N) cancer patients received intensity modulated radiation therapy. Before treatment, patient-specific quality assurance was conducted via beam-by-beam analysis, and beam-specific dose error distributions were generated. The predicted 3-dimensional (3D) dose distribution was calculated by back-projection of relative dose error distribution per beam. A 3D gamma analysis of different organs (prostate: clinical [CTV] and planned target volumes [PTV], rectum, bladder, femoral heads; H&N: gross tumor volume [GTV], CTV,more » spinal cord, brain stem, both parotids) was performed using predicted and planned dose distributions under 2%/2 mm tolerance and physical gamma passing rate was calculated. TCP and NTCP values were calculated for voxels with physical gamma indices (PGI) >1. We propose a new radiobiological gamma index (RGI) to quantify the radiobiological effects of TCP and NTCP and calculate radiobiological gamma passing rates. Results: The mean RGI gamma passing rates for prostate cases were significantly different compared with those of PGI (P<.03–.001). The mean RGI gamma passing rates for H&N cases (except for GTV) were significantly different compared with those of PGI (P<.001). Differences in gamma passing rates between PGI and RGI were due to dose differences between the planned and predicted dose distributions. Radiobiological gamma distribution was visualized to identify areas where the dose was radiobiologically important. Conclusions: RGI was proposed to integrate radiobiological effects into PGI. This index would assist physicians and medical physicists not only in physical evaluations of treatment delivery accuracy, but also in clinical evaluations of predicted dose distribution.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nicolato, Antonio; Lupidi, Francesco; Section of Sterotactic and Functional Neurosurgery, University of Verona and University Hospital, Verona

    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 (25.7more » 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.« less

  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

    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. 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. 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 months (range 1-65 months

  16. Quantifying and improving the efficiency of Gamma Knife treatment plans for brain metastases: results of a 1-year audit.

    PubMed

    Wright, Gavin; Hatfield, Paul; Loughrey, Carmel; Reiner, Beatrice; Bownes, Peter

    2014-12-01

    % vs 99%, median PCI 0.84 vs 0.83, p = 0.449, and median GI 2.72 vs 2.67, p = 0.701, audited plans vs initial plans, respectively). Choice of planning strategy can substantially affect plan efficiency and thus strongly influence treatment time. Through increased emphasis on efficiency, resulting from the introduction of PEI combined with a modified planning strategy informed by previous work, it has been possible to reduce times for metastatic plans without compromising their dosimetric quality. Although the average time savings achieved per lesion are moderate, the potential benefits per patient are greater for those with multiple metastases. Reducing treatment times has clear benefits with regard to patient comfort and throughput. In addition, optimization of plan efficiency may potentially affect the biologically effective dose from Gamma Knife treatments and offers opportunity for further work.

  17. Gamma-ray dose from an overhead plume

    DOE PAGES

    McNaughton, Michael W.; Gillis, Jessica McDonnel; Ruedig, Elizabeth; ...

    2017-05-01

    Standard plume models can underestimate the gamma-ray dose when most of the radioactive material is above the heads of the receptors. Typically, a model is used to calculate the air concentration at the height of the receptor, and the dose is calculated by multiplying the air concentration by a concentration-to-dose conversion factor. Models indicate that if the plume is emitted from a stack during stable atmospheric conditions, the lower edges of the plume may not reach the ground, in which case both the ground-level concentration and the dose are usually reported as zero. However, in such cases, the dose frommore » overhead gamma-emitting radionuclides may be substantial. Such underestimates could impact decision making in emergency situations. The Monte Carlo N-Particle code, MCNP, was used to calculate the overhead shine dose and to compare with standard plume models. At long distances and during unstable atmospheric conditions, the MCNP results agree with the standard models. As a result, at short distances, where many models calculate zero, the true dose (as modeled by MCNP) can be estimated with simple equations.« less

  18. Poster — Thur Eve — 23: Dose and Position Quality Assurance using the RADPOS System for 4D Radiotherapy with CyberKnife

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marants, R; Vandervoort, E; Cygler, J E

    2014-08-15

    Introduction: RADPOS 4D dosimetry system consists of a microMOSFET dosimeter combined with an electromagnetic positioning sensor, which allows for performing real-time dose and position measurements simultaneously. In this report the use of RADPOS as an independent quality assurance (QA) tool during CyberKnife 4D radiotherapy treatment is described. In addition to RADPOS, GAFCHROMIC® films were used for simultaneous dose measurement. Methods: RADPOS and films were calibrated in a Solid Water® phantom at 1.5 cm depth, SAD= 80 cm, using 60 mm cone. CT based treatment plan was created for a Solid Water® breast phantom containing metal fiducials and RADPOS probe. Dosemore » calculations were performed using iPlan pencil beam algorithm. Before the treatment delivery, GAFCHROMIC® film was inserted inside the breast phantom, next to the RADPOS probe. Then the phantom was positioned on the chest platform of the QUASAR, to which Synchrony LED optical markers were also attached. Position logging began for RADPOS and the Synchrony tracking system, the QUASAR motion was initiated and the treatment was delivered. Results: RADPOS position measurements very closely matched the LED marker positions recorded by the Synchrony camera tracking system. The RADPOS measured dose was 2.5% higher than the average film measured dose, which is within the experimental uncertainties. Treatment plan calculated dose was 4.1 and 1.6% lower than measured by RADPOS and film, respectively. This is most likely due to the inferior nature of the dose calculation algorithm. Conclusions: Our study demonstrates that RADPOS system is a useful tool for independent QA of CyberKnife treatments.« less

  19. 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

  20. Gamma Knife radiosurgery for vestibular schwannoma: case report and review of the literature

    PubMed Central

    2009-01-01

    Vestibular schwannomas, also called acoustic neuromas, are benign tumors of the vestibulocochlear nerve. Patients with these tumours almost always present with signs of hearing loss, and many also experience tinnitus, vertigo, and equilibrium problems. Following diagnosis with contrast enhanced MRI, patients may choose to observe the tumour with subsequent scans or seek active treatment in the form of microsurgery, radiosurgery, or radiotherapy. Unfortunately, definitive guidelines for treating vestibular schwannomas are lacking, because of insufficient evidence comparing the outcomes of therapeutic modalities. We present a contemporary case report, describing the finding of a vestibular schwannoma in a patient who presented with dizziness and a "clicking" sensation in the ear, but no hearing deficit. Audible clicking is a symptom that, to our knowledge, has not been associated with vestibular schwannoma in the literature. We discuss the diagnosis and patient's decision-making process, which led to treatment with Gamma Knife radiosurgery. Treatment resulted in an excellent radiographic response and complete hearing preservation. This case highlights an atypical presentation of vestibular schwannoma, associated with audible "clicks" and normal hearing. We also provide a concise review of the available literature on modern vestibular schwannoma treatment, which may be useful in guiding treatment decisions. PMID:20021676

  1. Long-Term Survival of a Patient with Brainstem and Recurrent Brain Metastasis from Stage IV Nonsmall Cell Lung Cancer Treated with Multiple Gamma Knife Radiosurgeries and Craniotomies: A Case Report and Review of the Literature

    PubMed Central

    Lamm, Andrew F.; Elaimy, Ameer L.; Mackay, Alexander R.; Fairbanks, Robert K.; Demakas, John J.; Cooke, Barton S.; Lee, Christopher M.; Taylor, Blake S.; Lamoreaux, Wayne T.

    2012-01-01

    The prognosis of patients diagnosed with stage IV nonsmall cell lung cancer that have brain and brainstem metastasis is very poor, with less than a third surviving a year past their initial date of diagnosis. We present the rare case of a 57-year-old man who is a long-term survivor of brainstem and recurrent brain metastasis, after aggressive treatment. He is now five and a half years out from diagnosis and continues to live a highly functional life without evidence of disease. Four separate Gamma Knife stereotactic radiosurgeries in conjunction with two craniotomies were utilized since his initial diagnosis to treat recurrent brain metastasis while chemoradiation therapy and thoracic surgery were used to treat his primary disease in the right upper lung. In his situation, Gamma Knife radiosurgery proved to be a valuable, safe, and effective tool for the treatment of multiply recurrent brain metastases within critical normal structures. PMID:23056973

  2. Finnish spectrolite as high-dose gamma detector

    NASA Astrophysics Data System (ADS)

    Antonio, Patrícia L.; Caldas, Linda V. E.

    2015-11-01

    A natural material called spectrolite, from Finland, was studied in this work. The purpose was to test it in gamma radiation beams to verify its performance as a high-dose detector. From this material, pellets were manufactured with two different concentrations of Teflon and spectrolite, and their responses were verified using two luminescent techniques: thermoluminescence (TL) and optically stimulated luminescence (OSL). The TL and OSL signals were evaluated by means of characterization tests of the material response, after exposure to a nominal absorbed dose interval of 5 Gy to 10 kGy. The results obtained, for both concentrations, showed a good performance of this material in beams of high-dose gamma radiation. Both techniques were utilized in order to investigate the properties of the spectrolite+Teflon samples for different applications.

  3. Gamma Knife radiosurgery for treatment of growing vestibular schwannomas in patients with neurofibromatosis Type 2: a matched cohort study with sporadic vestibular schwannomas.

    PubMed

    Kruyt, Ivo J; Verheul, Jeroen B; Hanssens, Patrick E J; Kunst, Henricus P M

    2018-01-01

    OBJECTIVE Neurofibromatosis Type 2 (NF2) is a tumor syndrome characterized by an autosomal dominant pattern of inheritance. The hallmark of NF2 is the development of bilateral vestibular schwannomas (VSs), generally by 30 years of age. One of the first-line treatment options for small to medium-large VSs is radiosurgery. Although radiosurgery shows excellent results in sporadic VS, its use in NF2-related VS is still a topic of dispute. The aim of this study was to evaluate long-term tumor control, hearing preservation rates, and factors influencing outcome of optimally dosed, contemporary Gamma Knife radiosurgery (GKRS) for growing VSs in patients with NF2 and compare the findings to data obtained in patients with sporadic VS also treated by means of GKRS. METHODS The authors performed a retrospective analysis of 47 growing VSs in 34 NF2 patients who underwent GKRS treatment performed with either the Model C or Perfexion Leksell Gamma Knife, with a median margin dose of 11 Gy. Actuarial tumor control rates were estimated using the Kaplan-Meier method. For patient- and treatment-related factors, a Cox proportional hazards model was used to identify predictors of outcome. Trigeminal, facial, and vestibulocochlear nerve function were assessed before and after treatment. NF2-related VS patients were matched 1:1 with sporadic VS patients who were treated in the same institute, and the same indications for treatment, definitions, and dosimetry were used in order to compare outcomes. RESULTS Actuarial tumor control rates in NF2 patients after 1, 3, 5, and 8 years were 98%, 89%, 87%, and 87%, respectively. Phenotype and tumor volume had significant hazard rates of 0.086 and 22.99, respectively, showing that Feiling-Gardner phenotype and a tumor volume not exceeding 6 cm 3 both were associated with significantly better outcome. Actuarial rates of serviceable hearing preservation after 1, 3, 5, and 7 years were 95%, 82%, 59%, and 33%, respectively. None of the patients

  4. A study on rectal dose measurement in phantom and in vivo using Gafchromic EBT3 film in IMRT and CyberKnife treatments of carcinoma of prostate

    PubMed Central

    Ganapathy, K.; Kurup, P. G. G.; Murali, V.; Muthukumaran, M.; Subramanian, S. Balaji; Velmurugan, J.

    2013-01-01

    The objective of this study is to check the feasibility of in vivo rectal dose measurement in intensity-modulated radiotherapy (IMRT) and CyberKnife treatments for carcinoma prostate. An in-house pelvis phantom made with bee's wax was used in this study. Two cylindrical bone equivalent materials were used to simulate the femur. Target and other critical structures associated with carcinoma prostate were delineated on the treatment planning images by the radiation oncologist. IMRT treatment plan was generated in Oncentra Master Plan treatment planning system and CyberKnife treatment plan was generated in Multiplan treatment planning system. Dose measurements were carried out in phantom and in patient using Gafchromic EBT3 films. RIT software was used to analyze the dose measured by EBT3 films. The measured doses using EBT3 films were compared with the TPS-calculated dose along the anterior rectal wall at multiple points. From the in-phantom measurements, it is observed that the difference between calculated and measured dose was mostly within 5%, except for a few measurement points. The difference between calculated and measured dose in the in-patient measurements was higher than 5% in regions which were away from the target. Gafchromic EBT3 film is a suitable detector for in vivo rectal dose measurements as it offers the possibility of analyzing the dose at multiple points. In addition, the method of extending this in vivo rectal dose measurement technique as a tool for patient-specific quality assurance check is also analyzed. PMID:24049320

  5. Evaluation of fractionated radiotherapy and gamma knife radiosurgery in cavernous sinus meningiomas: treatment strategy.

    PubMed

    Metellus, Philipe; Regis, Jean; Muracciole, Xavier; Fuentes, Stephane; Dufour, Henry; Nanni, Isabelle; Chinot, Oliver; Martin, Pierre-Marie; Grisoli, Francois

    2005-11-01

    To investigate the respective role of fractionated radiotherapy (FR) and gamma knife stereotactic (GKS) radiosurgery in cavernous sinus meningioma (CSM) treatment. The authors report the long-term follow-up of two populations of patients harboring CSMs treated either by FR (Group I, 38 patients) or GKS radiosurgery (Group II, 36 patients). There were 31 females with a mean age of 53 years in Group I and 29 females with a mean age of 51.2 years in Group II. In 20 patients (Group I) and 13 patients (Group II), FR and GKS radiosurgery were performed as an adjuvant treatment. In 18 patients (Group I) and in 23 patients (Group II), FR and GKS radiosurgery were performed as first line treatment. In our early experience with GKS radiosurgery (1992, date of gamma knife availability in the department), patients with tumors greater than 3 cm, showing close relationship with the optic apparatus (<3 mm) or skull base dural spreading, were treated by FR. Secondarily, with the advent of new devices and our growing experience, these criteria have evolved. The median follow-up period was 88.6 months (range, 42-168 mo) for Group I and 63.6 months (range, 48-92 mo) for Group II. According to Sekhar's classification, 26 (68.4%) patients were Grade III to IV in Group I and 10 (27.8%) patients in Group II (P < 0.05); 23 (60.5%) patients had extensive lesions in Group I and 7 (19.4%) patients in Group II (P < 0.05). Mean tumor volume was 13.5 cm in Group I and 5.2 cm in Group II (P < 0.05). Actuarial progression-free survival was 94.7% and 94.4% in Group I and II, respectively. Clinically, improvement was seen for 24 (63.2%) patients in Group I and for 21 (53.8%) patients in Group II (P > 0.05). Radiologically, 11 (29%, Group I) patients and 19 (Group II, 52.7%) patients showed tumor shrinkage (P = 0.04). Transient morbidity was 10.5% in Group I and 2.8% in Group II. Permanent morbidity was 2.6% in Group I and 0% in Group II. FR and GKS radiosurgery are safe and efficient techniques in

  6. Early versus late Gamma Knife radiosurgery following transsphenoidal surgery for nonfunctioning pituitary macroadenomas: a multicenter matched-cohort study.

    PubMed

    Pomeraniec, I Jonathan; Kano, Hideyuki; Xu, Zhiyuan; Nguyen, Brandon; Siddiqui, Zaid A; Silva, Danilo; Sharma, Mayur; Radwan, Hesham; Cohen, Jonathan A; Dallapiazza, Robert F; Iorio-Morin, Christian; Wolf, Amparo; Jane, John A; Grills, Inga S; Mathieu, David; Kondziolka, Douglas; Lee, Cheng-Chia; Wu, Chih-Chun; Cifarelli, Christopher P; Chytka, Tomas; Barnett, Gene H; Lunsford, L Dade; Sheehan, Jason P

    2017-10-27

    OBJECTIVE Gamma Knife radiosurgery (GKRS) is frequently used 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 imaging-defined progression of tumor. Given the high incidence of adenoma progression after subtotal resection over time, the present study intended to evaluate the effect of timing of radiosurgery on outcome. METHODS This is a multicenter retrospective review of patients with nonfunctioning pituitary macroadenomas who underwent transsphenoidal surgery followed by GKRS from 1987 to 2015 at 9 institutions affiliated with the International Gamma Knife Research Foundation. Patients were matched by adenoma and radiosurgical parameters and stratified based on the interval between last resection and radiosurgery. Operative results, imaging data, and clinical outcomes were compared across groups following early (≤ 6 months after resection) or late (> 6 months after resection) radiosurgery. RESULTS After matching, 222 patients met the authors' study criteria (from an initial collection of 496 patients) and were grouped based on early (n = 111) or late (n = 111) GKRS following transsphenoidal surgery. There was a greater risk of tumor progression after GKRS (p = 0.013) and residual tumor (p = 0.038) in the late radiosurgical group over a median imaging follow-up period of 68.5 months. No significant difference in the occurrence of post-GKRS endocrinopathy was observed (p = 0.68). Thirty percent of patients without endocrinopathy in the early cohort developed new endocrinopathies during the follow-up period versus 27% in the late cohort (p = 0.84). Fourteen percent of the patients in the early group and 25% of the patients in the late group experienced the resolution of endocrine dysfunction after original presentation (p = 0.32). CONCLUSIONS In this study, early GKRS was associated with a lower risk of

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Varughese, Jobin Kotakkathu, E-mail: jobinv@gmail.com; Wentzel-Larsen, Tore; Centre for Child and Adolescent Mental Health, Eastern and Southern Norway, Oslo

    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)more » 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.« less

  8. A minimally invasive treatment option for large metastatic brain tumors: long-term results of two-session Gamma Knife stereotactic radiosurgery

    PubMed Central

    2014-01-01

    Background Large brain metastases (BM) remain a significant cause of morbidity and death for cancer patients despite current advances in multimodality therapies. The goal of the present study was to evaluate the efficacy and limitations of 2-session Gamma Knife stereotactic radiosurgery (SRS) for patients with large BM. Methods This is a prospective, open-label and single arm study analyzing 58 consecutive patients who received 2-session SRS for large BM (≥ 10 mL). The median age was 66 years, and the median Karnofsky performance status (KPS) score was 70. SRS was the initial treatment in 51 large tumors (84%) and was used as salvage after failed prior treatments for 10 tumors (16%). The fraction protocol was 20-30 Gy given in 2 fractions with 3–4 weeks between fractions. Overall survival (OS) and neurological death (ND), local tumor control and KPS were analyzed. Results The median follow-up time was 9.0 months. One- and 2-year OS rates were 47% and 20%, respectively. The median OS time was 11.8 months (95% CI: 5.5-15.6). The causes of death were intracranial local progression in 5 cases, meningeal carcinomatosis in 3 and progression of the primary lesion in 39. One- and 2-year ND-free survival rates were 91% and 84%, respectively. In 52 of 61 large BM (85%) with sufficient radiological follow-up data, 6- and 12-month local tumor control rates were 85% and 64%, respectively. The mean KPS improved from 70 at the 1st SRS to 82 at the 2nd; the first follow-up mean KPS was 87 (P < 0.001). Symptomatic radiation injury developed and required conservative treatment in 3 patients (5%). Conclusions Long-term follow-up showed that two-session Gamma Knife SRS achieved durable tumor control rates as well as acceptable treatment-related morbidity. This treatment method may potentially merit being offered to patients with large BM who are in poor condition or are otherwise ineligible for standard care. PMID:24917309

  9. Management of brain metastasis in a patient with advanced epithelial ovarian carcinoma by gamma-knife radiosurgery.

    PubMed

    Nikolaoul, Marinos; Stamenković, Srdjan; Stergiou, Christos; Skarleas, Christos; Torrens, Michael

    2015-01-01

    Brain metastases from epithelial ovarian cancer (EOC) are rare events. We present a rare case of single ovarian cancer metastasis to the brain treated with gamma-knife radiosurgery (GKRS). A 65-year-old woman with advanced EOC presented with severe neurologic symptoms. A single brain metastasis of 3.2 cm with surrounding edema in the left parietal lobe was detected by brain magnetic resonance imaging (MRI) scan during the work-up. The decision to perform GKRS was due to a surgical inaccessibility of intracranial lesion. Twelve weeks after the procedure, the MRI scan showed reduction in the diameter of brain metastasis and surrounding edema and the patient returned to good mental and motor performance.The patient survived for 22 months following treatment and died from a progressive intra-abdominal disease. Prognosis of ovarian cancer patients with brain metastases is generally poor regardless of treatment. Our case shows that GKRS as primary treatment modality for the control of ovarian cancer metastases to the brain was effective and can be considered as a treatment of choice if international selection criteria are followed.

  10. Prompt gamma imaging of proton pencil beams at clinical dose rate

    NASA Astrophysics Data System (ADS)

    Perali, I.; Celani, A.; Bombelli, L.; Fiorini, C.; Camera, F.; Clementel, E.; Henrotin, S.; Janssens, G.; Prieels, D.; Roellinghoff, F.; Smeets, J.; Stichelbaut, F.; Vander Stappen, F.

    2014-10-01

    In this work, we present experimental results of a prompt gamma camera for real-time proton beam range verification. The detection system features a pixelated Cerium doped lutetium based scintillation crystal, coupled to Silicon PhotoMultiplier arrays, read out by dedicated electronics. The prompt gamma camera uses a knife-edge slit collimator to produce a 1D projection of the beam path in the target on the scintillation detector. We designed the detector to provide high counting statistics and high photo-detection efficiency for prompt gamma rays of several MeV. The slit design favours the counting statistics and could be advantageous in terms of simplicity, reduced cost and limited footprint. We present the description of the realized gamma camera, as well as the results of the characterization of the camera itself in terms of imaging performance. We also present the results of experiments in which a polymethyl methacrylate phantom was irradiated with proton pencil beams in a proton therapy center. A tungsten slit collimator was used and prompt gamma rays were acquired in the 3-6 MeV energy range. The acquisitions were performed with the beam operated at 100 MeV, 160 MeV and 230 MeV, with beam currents at the nozzle exit of several nA. Measured prompt gamma profiles are consistent with the simulations and we reached a precision (2σ) in shift retrieval of 4 mm with 0.5 × 108, 1.4 × 108 and 3.4 × 108 protons at 100, 160 and 230 MeV, respectively. We conclude that the acquisition of prompt gamma profiles for in vivo range verification of proton beam with the developed gamma camera and a slit collimator is feasible in clinical conditions. The compact design of the camera allows its integration in a proton therapy treatment room and further studies will be undertaken to validate the use of this detection system during treatment of real patients.

  11. Usefulness of a novel slim type FlushKnife-BT over conventional FlushKnife-BT in esophageal endoscopic submucosal dissection.

    PubMed

    Ohara, Yoshiko; Toyonaga, Takashi; Hoshi, Namiko; Tanaka, Shinwa; Baba, Shinichi; Takihara, Hiroshi; Kawara, Fumiaki; Ishida, Tsukasa; Morita, Yoshinori; Umegaki, Eiji; Azuma, Takeshi

    2017-03-07

    To investigated the usefulness of a novel slim type ball-tipped FlushKnife (FlushKnife-BTS) over ball-tipped FlushKnife (FlushKnife-BT) in functional experiments and clinical practice. In order to evaluate the functionality of FlushKnife-BTS, water aspiration speed, resistance to knife insertion through the scope, and waterjet flushing speed were compared between FlushKnife-BTS and BT. In clinical practice, esophageal endoscopic submucosal dissection (ESD) performed using FlushKnife-BTS or BT by an experienced endoscopist between October 2015 and January 2016 were retrospectively reviewed. The treatment speed and frequency of removing and reinserting the knife to aspirate fluid and air during ESD sessions were analyzed. Functional experiments revealed that water aspiration speed by the endoscope equipped with a 2.8-mm working channel with FlushKnife-BTS was 7.7-fold faster than that with conventional FlushKnife-BT. Resistance to knife insertion inside the scope with a 2.8-mm working channel was reduced by 40% with FlushKnife-BTS. The waterjet flushing speed was faster with the use of FlushKnife-BT. In clinical practice, a comparison of 6 and 7 ESD using FlushKnife-BT and BTS, respectively, revealed that the median treatment speed was 25.5 mm 2 /min (range 19.6-30.3) in the BT group and 44.2 mm 2 /min (range 15.5-55.4) in the BTS group ( P = 0.0633). However, the median treatment speed was significantly faster with FlushKnife-BTS when the resection size was larger than 1000 m 2 ( n = 4, median 24.2 mm 2 /min, range 19.6-27.7 vs n = 4, median 47.4 mm 2 /min, range 44.2-55.4, P = 0.0209). The frequency of knife replacement was less in the BTS group (median 1.76 times in one hour, range 0-5.45) than in the BT group (7.02 times in one hour, range 4.23-15) ( P = 0.0065). Our results indicate that FlushKnife-BTS enhances the performance of ESD, particularly for large lesions, by improving air and fluid aspiration and knife insertion during ESD and reducing the frequency

  12. Usefulness of a novel slim type FlushKnife-BT over conventional FlushKnife-BT in esophageal endoscopic submucosal dissection

    PubMed Central

    Ohara, Yoshiko; Toyonaga, Takashi; Hoshi, Namiko; Tanaka, Shinwa; Baba, Shinichi; Takihara, Hiroshi; Kawara, Fumiaki; Ishida, Tsukasa; Morita, Yoshinori; Umegaki, Eiji; Azuma, Takeshi

    2017-01-01

    AIM To investigated the usefulness of a novel slim type ball-tipped FlushKnife (FlushKnife-BTS) over ball-tipped FlushKnife (FlushKnife-BT) in functional experiments and clinical practice. METHODS In order to evaluate the functionality of FlushKnife-BTS, water aspiration speed, resistance to knife insertion through the scope, and waterjet flushing speed were compared between FlushKnife-BTS and BT. In clinical practice, esophageal endoscopic submucosal dissection (ESD) performed using FlushKnife-BTS or BT by an experienced endoscopist between October 2015 and January 2016 were retrospectively reviewed. The treatment speed and frequency of removing and reinserting the knife to aspirate fluid and air during ESD sessions were analyzed. RESULTS Functional experiments revealed that water aspiration speed by the endoscope equipped with a 2.8-mm working channel with FlushKnife-BTS was 7.7-fold faster than that with conventional FlushKnife-BT. Resistance to knife insertion inside the scope with a 2.8-mm working channel was reduced by 40% with FlushKnife-BTS. The waterjet flushing speed was faster with the use of FlushKnife-BT. In clinical practice, a comparison of 6 and 7 ESD using FlushKnife-BT and BTS, respectively, revealed that the median treatment speed was 25.5 mm2/min (range 19.6-30.3) in the BT group and 44.2 mm2/min (range 15.5-55.4) in the BTS group (P = 0.0633). However, the median treatment speed was significantly faster with FlushKnife-BTS when the resection size was larger than 1000 m2 (n = 4, median 24.2 mm2/min, range 19.6-27.7 vs n = 4, median 47.4 mm2/min, range 44.2-55.4, P = 0.0209). The frequency of knife replacement was less in the BTS group (median 1.76 times in one hour, range 0-5.45) than in the BT group (7.02 times in one hour, range 4.23-15) (P = 0.0065). CONCLUSION Our results indicate that FlushKnife-BTS enhances the performance of ESD, particularly for large lesions, by improving air and fluid aspiration and knife insertion during ESD and

  13. SU-F-T-538: CyberKnife with MLC for Treatment of Large Volume Tumors: A Feasibility Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bichay, T; Mayville, A

    2016-06-15

    Purpose: CyberKnife is a well-documented modality for SRS and SBRT treatments. Typical tumors are small and 1–5 fractions are usually used. We determined the feasibility of using CyberKnife, with an InCise multileaf collimator option, for larger tumors undergoing standard dose and fractionation. The intent was to understand the limitation of using this modality for other external beam radiation treatments. Methods: Five tumors from different anatomical sites with volumes from 127.8 cc to 1,320.5 cc were contoured and planned on a Multiplan V5.1 workstation. The target average diameter ranged from 7 cm to 13 cm. The dose fractionation was 1.8–2.0 Gy/fractionmore » and 25–45 fractions for total doses of 45–81 Gy. The sites planned were: pancreas, head and neck, prostate, anal, and esophagus. The plans were optimized to meet conventional dose constraints based on various RTOG protocols for conventional fractionation. Results: The Multiplan treatment planning system successfully generated clinically acceptable plans for all sites studied. The resulting dose distributions achieved reasonable target coverage, all greater than 95%, and satisfactory normal tissue sparing. Treatment times ranged from 9 minutes to 38 minutes, the longest being a head and neck plan with dual targets receiving different doses and with multiple adjacent critical structures. Conclusion: CyberKnife, with the InCise multileaf collimation option, can achieve acceptable dose distributions in large volume tumors treated with conventional dose and fractionation. Although treatment times are greater than conventional accelerator time; target coverage and dose to critical structures can be kept within a clinically acceptable range. While time limitations exist, when necessary CyberKnife can provide an alternative to traditional treatment modalities for large volume tumors.« less

  14. Gamma knife treatment for refractory epilepsy in seizure focus localized by positron emission tomography/CT★

    PubMed Central

    Bai, Xia; Wang, Xuemei; Wang, Hongwei; Zhao, Shigang; Han, Xiaodong; Hao, Linjun; Wang, Xiangcheng

    2012-01-01

    A total of 80 patients with refractory epilepsy were recruited from the Inner Mongolia Medical College Affiliated Hospital. The foci of 60% of the patients could be positioned using a combined positron emission tomography/CT imaging modality. Hyper- and hypometabolism foci were examined as part of this study. Patients who had abnormal metabolism in positron emission tomography/CT imaging were divided into intermittent-phase group and the seizure-phase group. The intermittent-phase group was further divided into a single-focus group and a multiple-foci group according to the number of seizure foci detected by imaging. Following gamma knife treatment, seizure frequency was significantly lower in the intermittent-phase group and the seizure-phase group. Wieser’s classification reached Grade I or II in nearly 40% of patients. Seizure frequency was significantly lower following treatment, but Wieser’s classification score was significantly higher in the seizure-phase group compared with the intermittent-phase group. Seizure frequency was significantly lower following treatment in the single-focus group, but Wieser’s classification score was significantly higher in the single-focus group as compared with the multiple-foci group. PMID:25317147

  15. Investigation of natural effective gamma dose rates case study: Ardebil Province in Iran

    PubMed Central

    2012-01-01

    Gamma rays pose enough energy to induce chemical changes that may be biologically important for the normal functioning of body cells. The external exposure of human beings to natural environmental gamma radiation normally exceeds that from all man-made sources combined. In this research natural background gamma dose rates and corresponding annual effective doses were determined for selected cities of Ardebil province. Outdoor gamma dose rates were measured using an Ion Chamber Survey Meter in 105 locations in selected districts. Average absorbed doses for Ardebil, Sar-Ein, Germy, Neer, Shourabil Recreational Lake, and Kosar were determined as 265, 219, 344, 233, 352, and 358 nSv/h, respectively. Although dose rates recorded for Germi and Kosar are comparable with some areas with high natural radiation background, however, the dose rates in other districts are well below the levels reported for such locations. Average annual effective dose due to indoor and outdoor gamma radiation for Ardebil province was estimated as 1.73 (1.35–2.39) mSv, which is on average 2 times higher than the world population weighted average. PMID:23369115

  16. Plan delivery quality assurance for CyberKnife: Statistical process control analysis of 350 film-based patient-specific QAs.

    PubMed

    Bellec, J; Delaby, N; Jouyaux, F; Perdrieux, M; Bouvier, J; Sorel, S; Henry, O; Lafond, C

    2017-07-01

    Robotic radiosurgery requires plan delivery quality assurance (DQA) but there has never been a published comprehensive analysis of a patient-specific DQA process in a clinic. We proposed to evaluate 350 consecutive film-based patient-specific DQAs using statistical process control. We evaluated the performance of the process to propose achievable tolerance criteria for DQA validation and we sought to identify suboptimal DQA using control charts. DQAs were performed on a CyberKnife-M6 using Gafchromic-EBT3 films. The signal-to-dose conversion was performed using a multichannel-correction and a scanning protocol that combined measurement and calibration in a single scan. The DQA analysis comprised a gamma-index analysis at 3%/1.5mm and a separate evaluation of spatial and dosimetric accuracy of the plan delivery. Each parameter was plotted on a control chart and control limits were calculated. A capability index (Cpm) was calculated to evaluate the ability of the process to produce results within specifications. The analysis of capability showed that a gamma pass rate of 85% at 3%/1.5mm was highly achievable as acceptance criteria for DQA validation using a film-based protocol (Cpm>1.33). 3.4% of DQA were outside a control limit of 88% for gamma pass-rate. The analysis of the out-of-control DQA helped identify a dosimetric error in our institute for a specific treatment type. We have defined initial tolerance criteria for DQA validations. We have shown that the implementation of a film-based patient-specific DQA protocol with the use of control charts is an effective method to improve patient treatment safety on CyberKnife. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  17. Magnetic resonance imaging characteristics and the prediction of outcome of vestibular schwannomas following Gamma Knife radiosurgery.

    PubMed

    Wu, Chih-Chun; Guo, Wan-Yuo; Chung, Wen-Yuh; Wu, Hisu-Mei; Lin, Chung-Jung; Lee, Cheng-Chia; Liu, Kang-Du; Yang, Huai-Che

    2017-12-01

    OBJECTIVE Gamma Knife surgery (GKS) is a promising treatment modality for patients with vestibular schwannomas (VSs), but a small percentage of patients have persistent postradiosurgical tumor growth. The aim of this study was to determine the clinical and quantitative MRI features of VS as predictors of long-term tumor control after GKS. METHODS The authors performed a retrospective study of all patients with VS treated with GKS using the Leksell Gamma Knife Unit between 2005 and 2013 at their institution. A total of 187 patients who had a minimum of 24 months of clinical and radiological assessment after radiosurgery were included in this study. Those who underwent a craniotomy with tumor removal before and after GKS were excluded. Study patients comprised 85 (45.5%) males and 102 (54.5%) females, with a median age of 52.2 years (range 20.4-82.3 years). Tumor volumes, enhancing patterns, and apparent diffusion coefficient (ADC) values were measured by region of interest (ROI) analysis of the whole tumor by serial MRI before and after GKS. RESULTS The median follow-up period was 60.8 months (range 24-128.9 months), and the median treated tumor volume was 3.54 cm 3 (0.1-16.2 cm 3 ). At last follow-up, imaging studies indicated that 150 tumors (80.2%) showed decreased tumor volume, 20 (10.7%) had stabilized, and 17 (9.1%) continued to grow following radiosurgery. The postradiosurgical outcome was not significantly correlated with pretreatment volumes or postradiosurgical enhancing patterns. Tumors that showed regression within the initial 12 months following radiosurgery were more likely to have a larger volume reduction ratio at last follow-up than those that did not (volume reduction ratio 55% vs 23.6%, respectively; p < 0.001). Compared with solid VSs, cystic VSs were more likely to regress or stabilize in the initial postradiosurgical 6-12-month period and during extended follow-up. Cystic VSs exhibited a greater volume reduction ratio at last follow-up (cystic

  18. RT-23THE ROLE OF GAMMA KNIFE RADIOSURGERY IN THE TREATMENT FOR PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMAS

    PubMed Central

    Mori, Kanji; Chiba, Yasuyoshi; Toyota, Shingo; Kumagai, Tetsuya; Yamamoto, Shota; Sugano, Hirohumi; Taki, Takuyu

    2014-01-01

    To evaluate the role of gamma knife (GK) as a treatment modality for primary central nervous system lymphomas (PCNSL), we reviewed PCNSL patients who were treated with GK between November 2004 and May 2014, retrospectively. There were 29 cases (13 males and 16 females, ranged from 33 years old to 91 years old) with 210 treated lesions. Marginal dose was from 12Gy to 18 Gy. One hundred and nineteen lesions of 23 cases could be accessed and all of them showed partial response or complete response. In seven cases, GK was performed at initial treatment, in 18 cases at recurrence, and in four cases at both. Median age of initial treatment group were significantly higher than that of recurred group (77.8 y.o. and 63.6 y.o., p = 0.00268). Two cases of initial treatment group and 16 cases of recurrent group were treated with whole brain radiation therapy (WBRT). GK after first relapse, progression free survival more than six months were obtained for six cases (33.3%), and four of them were free from additional therapy more than one year. Otherwise, thirteen cases (59.1%) received GK repeatedly (2-6 times, median = 3), and interval between each therapy was from 22 to 513 days (median = 93days). We confirmed that GK has high potential for local control. And it was supposed that GK was used as an alternative to WBRT at initial treatment for elderly, or selected to recurrent cases after WBRT. These results showed the role of GK in the treatment for PCNSL is palliative care, now in Japan. But it is clear that there exist patients who can live longer without WBRT by GK. We conclude that GK will become to play a more positive role by modifying its timing and modalities used together.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dhople, Anil; Kwok, Young; Chin, Lawrence

    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: Withmore » 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.« less

  20. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Feasibility of Multiple Repeat Gamma Knife Radiosurgeries for Trigeminal Neuralgia: A Case Report and Review of the Literature

    PubMed Central

    Jones, Guy C.; Elaimy, Ameer L.; Demakas, John J.; Jiang, Hansi; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Mackay, Alexander R.; Cooke, Barton S.; Lee, Christopher M.

    2011-01-01

    Treatment options for trigeminal neuralgia (TN) must be customized for the individual patient, and physicians must be aware of the medical, surgical, and radiation treatment modalities to prescribe optimal treatment courses for specific patients. The following case illustrates the potential for gamma knife radiosurgery (GKRS) to be repeated multiple times for the purpose of achieving facial pain control in cases of TN that have been refractory to other medical and surgical options, as well as prior GKRS. The patient described failed to achieve pain control with initial GKRS, as well as medical and surgical treatments, but experienced significant pain relief for a period of time with a second GKRS procedure and later underwent a third procedure. Only a small subset of patients have reportedly undergone more than two GKRS for TN; thus, further research and long-term clinical followup will be valuable in determining its usefulness in specific clinical situations. PMID:21904556

  2. Irradiation with low-dose gamma ray enhances tolerance to heat stress in Arabidopsis seedlings.

    PubMed

    Zhang, Liang; Zheng, Fengxia; Qi, Wencai; Wang, Tianqi; Ma, Lingyu; Qiu, Zongbo; Li, Jingyuan

    2016-06-01

    Gamma irradiation at low doses can stimulate the tolerance to environmental stress in plants. However, the knowledge regarding the mechanisms underlying the enhanced tolerance induced by low-dose gamma irradiation is far from fully understood. In this study, to investigate the physiological and molecular mechanisms of heat stress alleviated by low-dose gamma irradiation, the Arabidopsis seeds were exposed to a range of doses before subjected to heat treatment. Our results showed that 50-Gy gamma irradiation maximally promoted seedling growth in response to heat stress. The production rate of superoxide radical and contents of hydrogen peroxide and malondialdehyde in the seedlings irradiated with 50-Gy dose under heat stress were significantly lower than those of controls. The activities of antioxidant enzymes, glutathione (GSH) content and proline level in the gamma-irradiated seedlings were significantly increased compared with the controls. Furthermore, transcriptional expression analysis of selected genes revealed that some components related to heat tolerance were stimulated by low-dose gamma irradiation under heat shock. Our results suggest that low-dose gamma irradiation can modulate the physiological responses as well as gene expression related to heat tolerance, thus alleviating the stress damage in Arabidopsis seedlings. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Interfraction and intrafraction performance of the Gamma Knife Extend system for patient positioning and immobilization.

    PubMed

    Schlesinger, David; Xu, Zhiyuan; Taylor, Frances; Yen, Chun-Po; Sheehan, Jason

    2012-12-01

    The Extend system for the Gamma Knife Perfexion makes possible multifractional Gamma Knife treatments. The Extend system consists of a vacuum-monitored immobilization frame and a positioning measurement system used to determine the location of the patient's head within the frame at the time of simulation imaging and before each treatment fraction. The measurement system consists of a repositioning check tool (RCT), which attaches to the Extend frame, and associated digital measuring gauges. The purpose of this study is to evaluate the performance of the Extend system for patient repositioning before each treatment session (fraction) and patient immobilization between (interfraction) and during (intrafraction) each session in the first 10 patients (36 fractional treatments) treated at the University of Virginia. The RCT was used to acquire a set of reference measurements for each patient position at the time of CT simulation. Repositioning measurements were acquired before each fraction, and the patient position was adjusted until the residual radial difference from the reference position measurements was less than 1 mm. After treatment, patient position measurements were acquired, and the difference between those measurements and the ones obtained for patient position before the fraction was calculated as a measure of immobilization capability. Analysis of patient setup and immobilization performance included calculation of the group mean, standard deviation (SD), and distribution of systematic (components affecting all fractions) and random (per fraction) uncertainty components. Across all patients and fractions, the mean radial setup difference from the reference measurements was 0.64 mm, with an SD of 0.24 mm. The distribution of systematic uncertainty (Σ) was 0.17 mm, and the distribution of random uncertainty (σ) was 0.16 mm. The root mean square (RMS) differences for each plate of the RCT were as follows: right = 0.35 mm; left = 0.41 mm; superior = 0.28 mm

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, H; Yoon, J; Lee, E

    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 onmore » 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.« less

  5. Impact on cognitive functions following gamma knife radiosurgery for cerebral arteriovenous malformations

    PubMed Central

    Raghunath, A.; Bennett, Niranjana; Arimappamagan, Arivazhagan; Bhat, Dhananjaya I.; Srinivas, Dwarakanath; Thennarasu, K.; Jamuna, R.; Somanna, Sampath

    2016-01-01

    Background: Radiosurgery is an alternative to surgical resection of arteriovenous malformation (AVM). Very few studies have addressed the concern of radiation injury to the brain and its attendant adverse effects on cognitive function. Materials and Methods: This prospective study included all patients who underwent gamma knife radiosurgery (GKRS) at our institute for cerebral AVM between 2006 and December 2008 (n = 34). All patients underwent neuropsychological evaluation before the procedure. Neuropsychological evaluation was repeated in eighteen patients 2 years following GKRS. Clinical outcome, AVM obliteration, and factors influencing outcome were analyzed in these eighteen patients. Results: Before GKRS, more than 50% had significant impairment of neuropsychological functions compared to normal population norms. 66.6% achieved the excellent radiosurgical outcome. At 2 years follow-up, patients showed varied improvement in neuropsychological function in various categories. Pretherapeutic median value for percentage perseverative responses was 26.5 and at follow-up, it reduced to 18.2 (P = 0.039). Set shifting improved in 11 patients (61.1%), remained same in 5 patients (27.7%), and deteriorated in two patients (11.1%). Patients with a higher Spetzler-Martin grade AVM demonstrated a significantly more favorable shift in follow-up test values for set shifting function (P = 0.021). Patients with postradiation imaging changes had lesser tendency to improve in neuropsychological performance at follow-up. Conclusions: GKRS has no clinically harmful effect on cognitive and neuropsychological functioning in patients with brain AVM. On the contrary, there is an improvement in majority of patients at 2 years following radiosurgery when nidus is obliterated. PMID:26933340

  6. Impact on cognitive functions following gamma knife radiosurgery for cerebral arteriovenous malformations.

    PubMed

    Raghunath, A; Bennett, Niranjana; Arimappamagan, Arivazhagan; Bhat, Dhananjaya I; Srinivas, Dwarakanath; Thennarasu, K; Jamuna, R; Somanna, Sampath

    2016-01-01

    Radiosurgery is an alternative to surgical resection of arteriovenous malformation (AVM). Very few studies have addressed the concern of radiation injury to the brain and its attendant adverse effects on cognitive function. This prospective study included all patients who underwent gamma knife radiosurgery (GKRS) at our institute for cerebral AVM between 2006 and December 2008 (n = 34). All patients underwent neuropsychological evaluation before the procedure. Neuropsychological evaluation was repeated in eighteen patients 2 years following GKRS. Clinical outcome, AVM obliteration, and factors influencing outcome were analyzed in these eighteen patients. Before GKRS, more than 50% had significant impairment of neuropsychological functions compared to normal population norms. 66.6% achieved the excellent radiosurgical outcome. At 2 years follow-up, patients showed varied improvement in neuropsychological function in various categories. Pretherapeutic median value for percentage perseverative responses was 26.5 and at follow-up, it reduced to 18.2 (P = 0.039). Set shifting improved in 11 patients (61.1%), remained same in 5 patients (27.7%), and deteriorated in two patients (11.1%). Patients with a higher Spetzler-Martin grade AVM demonstrated a significantly more favorable shift in follow-up test values for set shifting function (P = 0.021). Patients with postradiation imaging changes had lesser tendency to improve in neuropsychological performance at follow-up. GKRS has no clinically harmful effect on cognitive and neuropsychological functioning in patients with brain AVM. On the contrary, there is an improvement in majority of patients at 2 years following radiosurgery when nidus is obliterated.

  7. SU-F-T-649: Dosimetric Evaluation of Non-Coplanar Arc Therapy Using a Novel Rotating Gamma Ray System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eldib, A; Chibani, O; Jin, L

    2016-06-15

    Purpose: Stereotactic intra and extra-cranial body radiation therapy has evolved with advances in treatment accuracy, effective radiation dose, and parameters necessary to maximize machine capabilities. Novel gamma systems with a ring type gantry were developed having the ability to perform oblique arcs. The aim of this study is to explore the dosimetric advantages of this new system. Methods: The rotating Gamma system is named CybeRay (Cyber Medical Corp., Xian, China). It has a treatment head of 16 cobalt-60 sources focused to the isocenter, which can rotate 360° on the ring gantry and swing 35° in the superior direction. Treatment plansmore » were generated utilizing our in-house Monte Carlo treatment planning system. A cylindrical phantom was modeled with 2mm voxel size. Dose inside the cylindrical phantom was calculated for coplanar and non-coplanar arcs. Dosimetric differences between CybeRay cobalt beams and CyberKnife 6MV beams were compared in a lung phantom and for previously treated SBRT patients. Results: The full width at half maxima of cross profiles in the S-I direction for the coplanar setup matched the cone sizes, while for the non-coplanar setup, FWHM was larger by 2mm for a 10mm cone and about 5mm for larger cones. In the coronal and sagittal view, coplanar beams showed elliptical shaped isodose lines, while non-coplanar beams showed circular isodose lines. Thus proper selection of the oblique angle and cone size can aid optimal dose matching to the target volume. Comparing a single 5mm cone from CybeRay to that from CyberKnife showed similar penumbra in a lung phantom but CybeRay had significant lower doses beyond lung tissues. Comparable treatment plans were obtained with CybeRay as that from CyberKnife.ConclusionThe noncoplanar multiple source arrangement of CybeRay will be of great clinical benefits for stereotactic intra and extra-cranial radiation therapy.« less

  8. Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico

    PubMed Central

    Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

    2015-01-01

    Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h−1. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th and 40K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h−1. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg−1, for 226Ra, 232Th and 40K, respectively. From the analysis, the spatial distribution of 232Th, 226Ra and 40K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize. PMID:26437425

  9. Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico.

    PubMed

    Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

    2015-09-30

    Determining ionizing radiation in a geographic area serves to assess its effects on a population's health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h(-1). At the same sites, 48 soil samples were taken to obtain the activity concentrations of (226)Ra, (232)Th and (40)K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h(-1). Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg(-1), for (226)Ra, (232)Th and (40)K, respectively. From the analysis, the spatial distribution of (232)Th, (226)Ra and (40)K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize.

  10. SU-F-T-554: Dark Current Effect On CyberKnife Beam Dosimetry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, H; Chang, A

    Purpose: All RF linear accelerators produce dark current to varying degrees when an accelerating voltage and RF input is applied in the absence of electron gun injection. This study is to evaluate how dark current from the linear accelerator of CyberKnife affect the dose in the reference dosimetry. Methods: The G4 CyberKnife system with 6MV photon beam was used in this study. Using the ion chamber and the diode detector, the dose was measured in water with varying time delay between acquiring charges and staring beam-on after applying high-voltage into the linear accelerator. The dose was measured after the timemore » delay with over the range of 0 to 120 seconds in the accelerating high-voltage mode without beam-on, applying 0, 10, 50, 100, and 200 MUs. For the measurements, the collimator of 60 mm was used and the detectors were placed at the depths of 10 cm with the source-to-surface distance of 80 cm. Results: The dark current was constant over time regardless of MU. The dose due to the dark current increased over time linearly with the R-squared value of 0.9983 up to 4.4 cGy for the time 120 seconds. In the dose rate setting of 720 MU/min, the relative dose when applying the accelerating voltage without beam-on was increased over time up to 0.6% but it was less than the leakage radiation resulted from the accelerated head. As the reference dosimetry condition, when 100 MU was delivered after 10 seconds time delay, the relative dose increased by 0.7% but 6.7% for the low MU (10 MU). Conclusion: In the dosimetry using CyberKnife system, the constant dark current affected to the dose. Although the time delay in the accelerating high-voltage mode without beam-on is within 10 seconds, the dose less than 100 cGy can be overestimated more than 1%.« less

  11. Neutron and gamma dose and spectra measurements on the Little Boy replica

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hoots, S.; Wadsworth, D.

    1984-06-01

    The radiation-measurement team of the Weapons Engineering Division at Lawrence Livermore National Laboratory (LLNL) measured neutron and gamma dose and spectra on the Little Boy replica at Los Alamos National Laboratory (LANL) in April 1983. This assembly is a replica of the gun-type atomic bomb exploded over Hiroshima in 1945. These measurements support the National Academy of Sciences Program to reassess the radiation doses due to atomic bomb explosions in Japan. Specifically, the following types of information were important: neutron spectra as a function of geometry, gamma to neutron dose ratios out to 1.5 km, and neutron attenuation in themore » atmosphere. We measured neutron and gamma dose/fission from close-in to a kilometer out, and neutron and gamma spectra at 90 and 30/sup 0/ close-in. This paper describes these measurements and the results. 12 references, 13 figures, 5 tables.« less

  12. 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…

  13. Tolerability and efficacy of gamma knife radiosurgery on hepatocellular carcinoma with portal vein tumor thrombosis

    PubMed Central

    Lu, Xiao-Jie; Dong, Jing; Ji, Li-Juan; Xiao, Li-Xin; Ling, Chang-Quan; Zhou, Jun

    2016-01-01

    This is a retrospective study on the safety and efficacy of gamma knife radiosurgery (GKR) in treating hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT). Patients with confirmed HCC and PVTT were allocated into two groups based on the treatments they received (palliative or GKR). A total of 138 patients were included (74 in the palliative group, 64 in GKR group). No significant differences in baseline characteristics existed between the two groups. Treatment-related adverse events (AEs) were recorded and compared between groups. The majority of AEs were mild to moderate and subsided naturally or after medication. There was no AE-induced death. The influences of baseline characteristics and treatment options on patients' OS were analyzed. The median OS of patients in the palliative and GKR group were 3.0 months (95% CI: 2.719-3.281) and 6.1 months (95% CI: 4.706-7.494) respectively (p = 0.003). Multivariate analysis revealed that GKR treatment, performance status 0-1, Child A, smaller tumor diameter and monolobar distribution were significant favorable prognosticators. Subgroup analyses showed OS benefit of GKR regardless of PVTT location (main or branch of PVTT). In conclusion, GKR is well tolerated in selected HCC-PVTT patients and can confer OS benefit, which needs validation in future prospective studies. PMID:26473291

  14. Variations of radon concentration in the atmosphere. Gamma dose rate

    NASA Astrophysics Data System (ADS)

    Tchorz-Trzeciakiewicz, D. E.; Solecki, A. T.

    2018-02-01

    The purposes of research were following: observation and interpretation of variations of radon concentration in the atmosphere - vertical, seasonal, spatial and analysis of relation between average annual radon concentration and ground natural radiation and gamma dose rate. Moreover we wanted to check the occurrence of radon density currents and the possibility of radon accumulation at the foot of the spoil tip. The surveys were carried out in Okrzeszyn (SW Poland) in the area of the spoil tip formed during uranium mining that took place in 60's of 20th century. The measurements were carried out in 20 measurements points at three heights: 0.2 m, 1 m and 2 m a.g.l. using SSNTD LR-115. The survey lasted one year and detectors were exchanged at the beginning of every season. Uranium eU (ppm), thorium eTh (ppm) and potassium K (%) contents were measured using gamma ray spectrometer Exploranium RS-230, ambient gamma dose rate using radiometer RK-100. The average radon concentration on this area was 52.8 Bq m-3. The highest radon concentrations were noted during autumn and the lowest during winter. We observed vertical variations of radon concentration. Radon concentrations decreased with increase of height above ground level. The decrease of radon with increase of height a.g.l. had logarithmic character. Spatial variations of radon concentrations did not indicate the occurrence of radon density currents and accumulation of radon at the foot of the spoil tip. The analysis of relation between average radon concentrations and ground natural radiation (uranium and thorium content) or gamma dose rate revealed positive relation between those parameters. On the base of results mentioned above we suggested that gamma spectrometry measurements or even cheaper and simpler ambient gamma dose rate measurements can be a useful tool in determining radon prone areas. This should be confirmed by additional research.

  15. 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

  16. Combination of water-jet dissection and needle-knife as a hybrid knife simplifies endoscopic submucosal dissection.

    PubMed

    Lingenfelder, Tobias; Fischer, Klaus; Sold, Moritz G; Post, Stefan; Enderle, Markus D; Kaehler, Georg F B A

    2009-07-01

    The safety and efficacy of endoscopic submucosal dissection (ESD) is very dependent on an effective injection beneath the submucosal lamina and on a controlled cutting technique. After our study group demonstrated the efficacy of the HydroJet in needleless submucosal injections under various physical conditions to create a submucosal fluid cushion (Selective tissue elevation by pressure = STEP technique), the next step was to develop a new instrument to combine the capabilities of an IT-Knife with a high-pressure water-jet in a single instrument. In this experimental study, we compared this new instrument with a standard ESD technique. Twelve gastric ESD were performed in six pigs under endotracheal anesthesia. Square areas measuring 4-cm x 4-cm were marked out on the anterior and posterior wall in the corpus-antrum transition region. The HybridKnife was used as an standard needle knife with insulated tip (i.e., the submucosal injection was performed with an injection needle and only the radiofrequency (RF) part of the HybridKnife was used for cutting (conventional technique)) or the HybridKnife was used in all the individual stages of the ESD, making use of the HybridKnife's combined functions (HybridKnife technique). The size of the resected specimens, the operating time, the frequency with which instruments were changed, the number of bleeding episodes, and the number of injuries to the gastric wall together with the subjective overall assessment of the intervention by the operating physician were recorded. The resected specimens were the same size, with average sizes of 16.96 cm(2) and 15.85 cm(2) resp (p = 0.8125). Bleeding episodes have been less frequent in the HybridKnife group (2.83 vs. 3.5; p = 0.5625). The standard knife caused more injuries to the lamina muscularis propria (0.17 vs. 1.33; p = 0.0313). The operating times had a tendency to be shorter with the HybridKnife technique (47.18 vs. 58.32 minute; p = 0.0313). The combination of a needle-knife

  17. Single‐fraction spine SBRT end‐to‐end testing on TomoTherapy, Vero, TrueBeam, and CyberKnife treatment platforms using a novel anthropomorphic phantom

    PubMed Central

    Kaufman, Isaac; Powell, Rachel; Pandya, Shalini; Somnay, Archana; Bossenberger, Todd; Ramirez, Ezequiel; Reynolds, Robert; Solberg, Timothy; Burmeister, Jay

    2015-01-01

    , respectively. Film measurements for the lumbar targets resulted in average global gamma index passing rates of 100% at 3%/3 mm, 96.9% at 2%/2 mm, and 61.8% at 1%/1 mm, with a 10% minimum threshold for all plans on all platforms. Local gamma analysis was also performed with similar results. While gamma passing rates were consistently accurate across all platforms through 2%/2 mm, treatment beam‐on delivery times varied greatly between each platform with TrueBeam FFF being shortest, averaging 4.4 min, TrueBeam using flattened beam at 9.5 min, TomoTherapy at 30.5 min, Vero at 19 min, and CyberKnife at 46.0 min. In spite of the complexity of the representative targets and their proximity to the spinal cord, all treatment platforms were able to create plans meeting all RTOG 0631 dose constraints and produced exceptional agreement between calculated and measured doses. However, there were differences in the plan characteristics and significant differences in the beam‐on delivery time between platforms. Thus, clinical judgment is required for each particular case to determine most appropriate treatment planning/delivery platform. PACS number: 87.53.Ly PMID:25679169

  18. 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.

  19. Gamma knife radiosurgery in patients with persistent acromegaly or Cushing's disease: long-term risk of hypopituitarism.

    PubMed

    Cohen-Inbar, Or; Ramesh, Arjun; Xu, Zhiyuan; Vance, Mary Lee; Schlesinger, David; Sheehan, Jason P

    2016-04-01

    For patient with a recurrent or residual acromegaly or Cushing's disease (CD) after resection, gamma knife radiosurgery (GKRS) is often used. Hypopituitarism is the most common adverse effect after GKRS treatment. The paucity of studies with long-term follow-up has hampered understanding of the latent risks of hypopituitarism in patients with acromegaly or CD. We report the long-term risks of hypopituitarism for patients treated with GKRS for acromegaly or CD. From a prospectively created, IRB-approved database, we identified all patients with acromegaly or CD treated with GKRS at the University of Virginia from 1989 to 2008. Only patients with a minimum endocrine follow-up of 60 months were included. The median follow-up is 159·5 months (60·1-278). Thorough radiological and endocrine assessments were performed immediately before GKRS and at regular follow-up intervals. New onset of hypopituitarism was defined as pituitary hormone deficits after GKRS requiring corresponding hormone replacement. Sixty patients with either acromegaly or CD were included. Median tumour volume at time of GKRS was 1·3 cm(3) (0·3-13·4), and median margin dose was 25 Gy (6-30). GKRS-induced new pituitary deficiency occurred in 58·3% (n = 35) of patients. Growth hormone deficiency was most common (28·3%, n = 17). The actuarial overall rates of hypopituitarism at 3, 5 and 10 years were 10%, 21·7% and 53·3%, respectively. The median time to hypopituitarism was 61 months after GKRS (range, 12-160). Cavernous sinus invasion of the tumour was found to correlate with the occurrence of a new or progressive hypopituitarism after GKRS (P = 0·018). Delayed hypopituitarism increases as a function of time after radiosurgery. Hormone axes appear to vary in terms of radiosensitivity. Patients with adenoma in the cavernous sinus are more prone to develop loss of pituitary function after GKRS. © 2015 John Wiley & Sons Ltd.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brezovich, I; Wu, X; Duan, J

    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 andmore » 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.« less

  1. [Design and application of silver needle-knife].

    PubMed

    Sun, Guodong; Shi, Bin; Zhang, Benwu; Xu, Haidong

    2015-04-01

    A silver needle-knife which has the dual function of silver needle and needle-knife is designed. The main components of this silver needle-knife are approximately 50% silver and approximately 50% nichrome. The silver needle-knife is composed of five parts, including needle-knife tail, spiral handle; steering handle, needle-knife body and needle-knife edge. It converges the advantages of needle-knife and silver needle, which can cut loose of diseased tissue and peel adhesion of lesions, but also be heated with moxa cone and thermal therapeutic instrument, and connect with electroacupuncture apparatus. It has the function of warming channel and removing coldness, dispelling wind and eliminating dampness, resolving spasm and relieving pain, dredging the channel and so on. Due to the spiral handle and the steering handle, the operation is easier, which reduces the blindness of cutting and increase the safety. It is mainly used for soft tissue injury, rheumatism and rheumatoid arthritis, as well as degenerative diseases of spine and joint, and it has obvious efficacy on some internal medical diseases.

  2. 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.

  3. Beta- and gamma-dose measurements of the Godiva IV critical assembly.

    PubMed

    Hankins, D E

    1984-03-01

    To aid in the re-evaluation of an exposure that occurred in 1963, information was required on the response of film badges to the beta- and gamma-ray doses from a critical assembly. Of particular interest was the beta spectra from the assembly. The techniques used and the results obtained in this study are of interest to health physicists at facilities where exposures to betas occur. The dose rates from the Los Alamos National Laboratory Godiva IV Critical Assembly were measured at numerous distances from the assembly four and 12 days following a burst. Information was obtained on the beta-particle spectra using absorption curve studies. The beta/gamma dose-rate ratio as a function of distance from the assembly was determined. Shielding provided by various metals, gloves and clothing was measured. The beta- and gamma-ray doses measured were compared with a film packet used in the past at the Nevada Test Site with two types of current TLD personnel badges. Measurements made with a commercial thin-window ion chamber instrument are compared with the dose rates obtained using other dosimeters.

  4. Determination of the gamma-ray skyshine dose contribution in a Loss Of Shielding accident

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dennis, M.L.; Weiner, R.F.; Osborn, D.M.

    2007-07-01

    The goal of this research is to determine the gamma-ray dose contribution from skyshine. In a transportation accident involving the loss of lead gamma shielding, first responders to the accident will be exposed to both direct gamma radiation streaming from the exposed spent nuclear fuel and atmospherically reflected gamma radiation. The reflected radiation is referred to as skyshine and should contribute minimally to the overall dose; however, when there is minimal shielding above the exposed source, skyshine at large distances from the source must be considered. The program SKYDOSE developed by Shultis and Faw evaluates the gamma-ray skyshine dose frommore » a point, isotropic, polyenergetic, gamma-photon source. Assuming an infinite black wall shielding all direct radiation, the model assumes a first responder is located at varying distances from the wall. Skyshine doses are calculated both through SKYDOSE's integral line-beam method and an approximate approach prescribed by the National Council of Radiation Protection and Measurements. Initial results from SKYDOSE indicate nearly equivalent dose rates from either direct or skyshine radiation at nine meters from the wall, which seemed unusual and not readily explained. NCRP methodology, however, yields skyshine dose rates which are drastically smaller than direct dose rates at the same distance. Further investigation using the program MicroSkyshine{sup R}, which allows a variety of source configurations, suggests skyshine contributes minimally to dose in a loss-of-shielding accident. (authors)« less

  5. [Infraoccipital needle-knife for cervical vertigo].

    PubMed

    Li, Shaofang; Huang, Manhua; Lin, Zhuopeng; Chen, Xinze; Lin, Dongna; Lu, Peng; Lu, Qu

    2017-03-12

    To observe the clinical effect differences between infraoccipital needle-knife and massage for cervical vertigo. A total of 366 patients with cervical vertigo were randomly assigned into a needle-knife group (186 cases) and a massage group (180 cases). With cases dropping excluded, 183 cases in the needle-knife group and 176 cases in the massage group were included. Needle-knife was used at Fengchi (GB 20), infraoccipital ashi point, etc. in the needle-knife group. The treatment was given for one course, once three days, 5 times as one course. The traditional massage was applied in the massage group for one course, including systematic stroking, kneading, and the application of pressure and plucking, etc., once every two days and 7 times as one course. The dizziness handicap inventory (DHI) score was observed before and after treatment, as well as 3, 6, and 12 months after treatment. The effects were also evaluated. The total effective rate was 92.3% (169/183) in the needle-knife group, which was better than 85.2% (150/176) in the massage group ( P <0.05). Compared with those before treatment, the DHI scores at all the observation time points after treatment were improved in the two groups (all P <0.05), with better improvements after treatment as well as 3 and 6 months after treatment in the needle-knife group (all P <0.05). There was no significant difference in the improvement of DHI scores between the two groups 12 months after treatment ( P >0.05). The recurrence rate was 10.3% (12/117) in the needle-knife group, and it was 10.7% (11/103) in the massage group 12 months after treatment ( P >0.05). Infraoccipital needle-knife achieves apparent effect for cervical vertigo, which is superior to massage in short period.

  6. Stereotactic radiosurgery for intracranial metastases: linac-based and gamma-dedicated unit approach.

    PubMed

    Alongi, Filippo; Fiorentino, Alba; Mancosu, Pietro; Navarria, Pierina; Giaj Levra, Niccolò; Mazzola, Rosario; Scorsetti, Marta

    2016-07-01

    For intracranial metastases, the role of stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy is well recognized. Historically, the first technology, for stereotactic device able to irradiate a brain tumor volume, was Gamma Knife® (GK). Due to the technological advancement of linear accelerator (Linac), there was a continuous increasing interest in SRS Linac-based applications. In those decades, it was assumed a superiority of GK compared to SRS Linac-based for brain tumor in terms of dose conformity and rapid fall-off dose close to the target. Expert commentary: Recently, due to the Linac technologic advancement, the choice of SRS GK-based is not necessarily so exclusive. The current review discussed in details the technical and clinical aspects comparing the two approaches for brain metastases.

  7. TL detectors for gamma ray dose measurements in criticality accidents.

    PubMed

    Miljanić, Saveta; Zorko, Benjamin; Gregori, Beatriz; Knezević, Zeljka

    2007-01-01

    Determination of gamma ray dose in mixed neutron+gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Bosković Institute (RBI), Croatia, JoZef Stefan Institute (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7LiF (TLD-700), CaF2:Mn and Al2O3:Mg,Y-all from RBI; CaF2:Mn from JSI and 7LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed.

  8. Gamma knife radiosurgery for essential tremor: A Case report and review of the literature

    PubMed Central

    2010-01-01

    Approximately 5 million people in America are affected by essential tremors (ET), which are classified as a type of benign movement disorder. This disease manifests as tremors that usually occur in the hands, but they may also be present in the head, face, tongue, and lower limbs. Radiofrequency thalamotomy (RF) and deep brain stimulation (DBS) are common invasive procedures with proven track records that are used to treat ET. Although these procedures have high success rates, they still put patients at risk of potential side effects and are invasive by nature. Thalamotomy using the gamma knife (GK) also produces favorable outcomes in treating tremors, without the complications associated with invasive neurosurgery procedures. This report describes the presenting symptoms and extended treatment outcome for a patient with an advanced case of ET, who received GK thalamotomy treatment six years ago. Because of this non-invasive treatment, she regained the ability to paint and live with an improved quality of life. We also discuss and review the relevant literature regarding the risks and benefits of this treatment modality. GK thalamotomy is one effective option for the treatment of ET, and due to its noninvasive nature, it has a different risk profile than neurosurgery. We suggest that GK thalamotomy should be presented as one viable treatment option to all ET patients, and should be recommended to those who would be best served by less invasive treatment techniques. PMID:20307307

  9. Histopathology of radiation necrosis with severe peritumoral edema after gamma knife radiosurgery for parasagittal meningioma. A report of two cases.

    PubMed

    Chen, Chien-hua; Shen, Chiung-chyi; Sun, Ming-hsi; Ho, William L; Huang, Chuan-fu; Kwan, Po-cheung

    2007-01-01

    Gamma knife radiosurgery (GKS) has been an effective treatment for meningiomas. Nevertheless, it still has certain risks. We present 2 cases of parasagittal meningioma after GKS complicated with radiation necrosis and peritumoral edema. The results of histologic examination are discussed. Two cases of parasagittal meningioma received GKS. Symptomatic peritumoral edema developed 3-4 months after GKS. Both of them underwent surgical resection of their tumor afterwards. Histologic examination showed necrotic change inside the tumor and infiltration of inflammatory cells in both cases. Hyalinization of blood vessels was seen in the 2nd case. The patients had improvement of neurologic function after surgical resection. Imaging performed 3 months after surgical resection showed alleviation of brain edema. After radiosurgery peritumoral edema tends to occur in meningiomas with a parasagittal position. Radiation necrosis, infiltration of inflammatory cells, and radiation injury to the vasculature causing hyalinization of blood vessels are suggested as the underlying histopathology. (c) 2007 S. Karger AG, Basel.

  10. A nomogram for predicting distant brain failure in patients treated with gamma knife stereotactic radiosurgery without whole brain radiotherapy

    PubMed Central

    Ayala-Peacock, Diandra N.; Peiffer, Ann M.; Lucas, John T.; Isom, Scott; Kuremsky, J. Griff; Urbanic, James J.; Bourland, J. Daniel; Laxton, Adrian W.; Tatter, Stephen B.; Shaw, Edward G.; Chan, Michael D.

    2014-01-01

    Background We review our single institution experience to determine predictive factors for early and delayed distant brain failure (DBF) after radiosurgery without whole brain radiotherapy (WBRT) for brain metastases. Materials and methods Between January 2000 and December 2010, a total of 464 patients were treated with Gamma Knife stereotactic radiosurgery (SRS) without WBRT for primary management of newly diagnosed brain metastases. Histology, systemic disease, RPA class, and number of metastases were evaluated as possible predictors of DBF rate. DBF rates were determined by serial MRI. Kaplan–Meier method was used to estimate rate of DBF. Multivariate analysis was performed using Cox Proportional Hazard regression. Results Median number of lesions treated was 1 (range 1–13). Median time to DBF was 4.9 months. Twenty-seven percent of patients ultimately required WBRT with median time to WBRT of 5.6 months. Progressive systemic disease (χ2= 16.748, P < .001), number of metastases at SRS (χ2 = 27.216, P < .001), discovery of new metastases at time of SRS (χ2 = 9.197, P < .01), and histology (χ2 = 12.819, P < .07) were factors that predicted for earlier time to distant failure. High risk histologic subtypes (melanoma, her2 negative breast, χ2 = 11.020, P < .001) and low risk subtypes (her2 + breast, χ2 = 11.343, P < .001) were identified. Progressive systemic disease (χ2 = 9.549, P < .01), number of brain metastases (χ2 = 16.953, P < .001), minimum SRS dose (χ2 = 21.609, P < .001), and widespread metastatic disease (χ2 = 29.396, P < .001) were predictive of shorter time to WBRT. Conclusion Systemic disease, number of metastases, and histology are factors that predict distant failure rate after primary radiosurgical management of brain metastases. PMID:24558022

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

    PubMed

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

    2011-05-01

    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). RS, randomized to 20 Gy or 24 Gy comprising 5.5-7.5 ml 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. Thirty patients were treated and 26 were available for the final 24-month neuropsychological evaluation. 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), and mood (Beck Depression Inventory) did not differ from baseline. QOL scores improved at 24 and 36 months, with those patients attaining seizure remission by month 24s accounting for the majority of the improvement. 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. Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.

  12. Neurogenic Effects of Low-Dose Whole-Body HZE (Fe) Ion and Gamma Irradiation.

    PubMed

    Sweet, Tara B; Hurley, Sean D; Wu, Michael D; Olschowka, John A; Williams, Jacqueline P; O'Banion, M Kerry

    2016-12-01

    Understanding the dose-toxicity profile of radiation is critical when evaluating potential health risks associated with natural and man-made sources in our environment. The purpose of this study was to evaluate the effects of low-dose whole-body high-energy charged (HZE) iron (Fe) ions and low-energy gamma exposure on proliferation and differentiation of adult-born neurons within the dentate gyrus of the hippocampus, cells deemed to play a critical role in memory regulation. To determine the dose-response characteristics of the brain to whole-body Fe-ion vs. gamma-radiation exposure, C57BL/6J mice were irradiated with 1 GeV/n Fe ions or a static 137 Cs source (0.662 MeV) at doses ranging from 0 to 300 cGy. The neurogenesis was analyzed at 48 h and one month postirradiation. These experiments revealed that whole-body exposure to either Fe ions or gamma radiation leads to: 1. An acute decrease in cell division within the dentate gyrus of the hippocampus, detected at doses as low as 30 and 100 cGy for Fe ions and gamma radiation, respectively; and 2. A reduction in newly differentiated neurons (DCX immunoreactivity) at one month postirradiation, with significant decreases detected at doses as low as 100 cGy for both Fe ions and gamma rays. The data presented here contribute to our understanding of brain responses to whole-body Fe ions and gamma rays and may help inform health-risk evaluations related to systemic exposure during a medical or radiologic/nuclear event or as a result of prolonged space travel.

  13. Neurogenic Effects of Low-Dose Whole-Body HZE (Fe) Ion and Gamma Irradiation

    PubMed Central

    Sweet, Tara B.; Hurley, Sean D.; Wu, Michael D.; Olschowka, John A.; Williams, Jacqueline P.; O’Banion, M. Kerry

    2017-01-01

    Understanding the dose-toxicity profile of radiation is critical when evaluating potential health risks associated with natural and man-made sources in our environment. The purpose of this study was to evaluate the effects of low-dose whole-body high-energy charged (HZE) iron (Fe) ions and low-energy gamma exposure on proliferation and differentiation of adult-born neurons within the dentate gyrus of the hippocampus, cells deemed to play a critical role in memory regulation. To determine the dose-response characteristics of the brain to whole-body Fe-ion vs. gamma-radiation exposure, C57BL/6J mice were irradiated with 1 GeV/n Fe ions or a static 137Cs source (0.662 MeV) at doses ranging from 0 to 300 cGy. The neurogenesis was analyzed at 48 h and one month postirradiation. These experiments revealed that whole-body exposure to either Fe ions or gamma radiation leads to: 1. An acute decrease in cell division within the dentate gyrus of the hippocampus, detected at doses as low as 30 and 100 cGy for Fe ions and gamma radiation, respectively; and 2. A reduction in newly differentiated neurons (DCX immunoreactivity) at one month postirradiation, with significant decreases detected at doses as low as 100 cGy for both Fe ions and gamma rays. The data presented here contribute to our understanding of brain responses to whole-body Fe ions and gamma rays and may help inform health-risk evaluations related to systemic exposure during a medical or radiologic/nuclear event or as a result of prolonged space travel. PMID:27905869

  14. Souvenir knife: a retained transcranial knife blade.

    PubMed

    Davis, Neil L; Kahana, Tzipi; Hiss, Jehuda

    2004-09-01

    Upon necroscopic examination of a homeless male found comatose in the street and pronounced dead at a medical center 12 hours later, a sharp tip of a knife lodged in the right parietal region of his skull was incidentally discovered. The blade transected the diploe and penetrated the cerebral cortex. Subsequent police investigation revealed that this was the remnant of a stabbing attempt on his life several months prior to his death. The cause of death was determined to be unrelated to the metallic blade fragment, thus making it a truly incidental and rare finding of a "souvenir knife." Nevertheless, since the injury sustained in the stabbing was potentially life threatening, the investigation into that assault was reopened.A case report is presented, along with a brief review of the literature on "souvenir objects."

  15. Suppressing effect of low-dose gamma-ray irradiation on collagen-induced arthritis.

    PubMed

    Nakatsukasa, Hiroko; Tsukimoto, Mitsutoshi; Ohshima, Yasuhiro; Tago, Fumitoshi; Masada, Ayako; Kojima, Shuji

    2008-07-01

    We previously reported attenuation of autoimmune disease by low-dose gamma-ray irradiation in MRL-lpr/lpr mice. Here, we studied the effect of low-dose gamma-ray irradiation on collagen-induced arthritis (CIA) in DBA/1J mice. Mice were immunized with type II collagen, and exposed to low-dose gamma-rays (0.5 Gy per week for 5 weeks). Paw swelling, redness, and bone degradation were suppressed by irradiation, which also delayed the onset of pathological change and reduced the severity of the arthritis. Production of tumor necrosis factor-alpha, interferon-gamma, and interleukin-6, which play important roles in the onset of CIA, was suppressed by the irradiation. The level of anti-type II collagen antibody, which is essential for the onset of CIA, was also lower in irradiated CIA mice. The population of plasma cells was increased in CIA mice, but irradiation blocked this increase. Since regulatory T cells are known to be involved in suppression of autoimmune disease, the population of CD4(+)CD25(+)Foxp3(+) regulatory T cells was measured. Intriguingly, a significant increase of these regulatory T cells was found in irradiated CIA mice. Overall, our data suggest that low-dose gamma-ray irradiation could attenuate CIA through suppression of pro-inflammatory cytokines and autoantibody production, and induction of regulatory T cells.

  16. Transcatheter arterial chemoembolization (TACE) combined with γ-knife compared to TACE or γ-knife alone for hepatocellular carcinoma.

    PubMed

    Cai, Yeyu; Chang, Qian; Xiao, Enhua; Shang, Quan-Liang; Chen, Zhu

    2018-06-01

    To compare the clinical efficacies and adverse reactions between transcatheter arterial chemoembolization (TACE), γ-ray 3-dimensional fractionated stereotactic conformal radiotherapy (FSCR), and TACE combined with FSCR for primary hepatocellular carcinoma.The study was approved by the Institutional Review Board, and informed consent was waived due to the retrospective study design. About 121 patients met the inclusion criteria and were included in this study, from March 2008 to January 2010, in the Second Xiangya Hospital. Forty-six patients underwent TACE alone, 36 patients underwent γ-knife alone, and 39 were treated by γ-knife combined with TACE. Short-term effects, overall survival rates, adverse reactions, and survival times were compared between the 3 treatment groups.Short-term effects were observed in 41.3% of the TACE group, 33.3% of the γ-knife group, and 64.1% of the TACE combined γ-knife group (P = .020). Overall survival rates at 6,12, 18, and 24 months were 50%, 34.8%, 28.3%, and 21.7% for the TACE group, 36.1%, 30.6%, 16.7%, and 11.1% for γ-knife group, and 84.6%, 71.8%, 61.5%, and 30.8% for TACE combined γ-knife group, respectively. The differences in the overall survival rates at 6, 12, and 18 months between the 3 groups were statistically significant (P = 0), but the overall survival rates at 24 months in the 3 groups were not significantly different (P = .117). The median survival time was 7 months for the TACE group, 3 months for the γ-knife group, and 20 months for the TACE combined γ-knife group (P = 0). There were statistically significant differences (P = .010) of leukopenia between the 3 groups, and no statistically significant differences of (P > .05) thrombocytopenia, anemia, nausea, vomiting, and liver function lesions.TACE combined with γ-knife for primary hepatocellular carcinoma is superior to TACE or γ-knife alone in short-term and long-term effects. This procedure is a mild, safe, and effective

  17. TH-A-BRC-02: AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Goetsch, S.

    AAPM TG-135U1 QA for Robotic Radiosurgery - Sonja Dieterich Since the publication of AAPM TG-135 in 2011, the technology of robotic radiosurgery has rapidly developed. AAPM TG-135U1 will provide recommendations on the clinical practice for using the IRIS collimator, fiducial-less real-time motion tracking, and Monte Carlo based treatment planning. In addition, it will summarize currently available literature about uncertainties. Learning Objectives: Understand the progression of technology since the first TG publication Learn which new QA procedures should be implemented for new technologies Be familiar with updates to clinical practice guidelines AAPM TG-178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance -more » Steven Goetsch Purpose: AAPM Task Group 178 Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance was formed in August, 2008. The Task Group has 12 medical physicists, two physicians and two consultants. Methods: A round robin dosimetry intercomparison of proposed ionization chambers, electrometer and dosimetry phantoms was conducted over a 15 month period in 2011 and 2012 (Med Phys 42, 11, Nov, 2015). The data obtained at 9 institutions (with ten different Elekta Gamma Knife units) was analyzed by the lead author using several protocols. Results: The most consistent results were obtained using the Elekta ABS 16cm diameter phantom, with the TG-51 protocol modified as recommended by Alfonso et al (Med Phys 35, 11, Nov 2008). A key white paper (Med Phys, in press) sponsored by Elekta Corporation, was used to obtain correction factors for the ionization chambers and phantoms used in this intercomparison. Consistent results were obtained for both Elekta Gamma Knife Model 4C and Gamma Knife Perfexion units as measured with each of two miniature ionization chambers. Conclusion: The full report gives clinical history and background of gamma stereotactic radiosurgery, clinical examples and history, quality assurance recommendations and

  18. Gamma knife surgery for refractory postherpetic trigeminal neuralgia: targeting in one session both the retrogasserian trigeminal nerve and the centromedian nucleus of the thalamus.

    PubMed

    Keep, Marcus F; DeMare, Paul A; Ashby, Lynn S

    2005-01-01

    The authors tested the hypothesis that two targets are needed to treat postherpetic trigeminal neuralgia (TN): one in the trigeminal nerve for the direct sharp pain and one in the thalamus for the diffuse burning pain. Three patients with refractory postherpetic TN were treated with gamma knife surgery (GKS) through a novel two-target approach. In a single treatment session, both the trigeminal nerve and centromedian nucleus were targeted. First, the trigeminal nerve, ipsilateral to the facial pain, was treated with 60 to 80 Gy. Second, the centromedian nucleus was localized using standard coordinates and by comparing magnetic resonance images with a stereotactic atlas. A single dose of 120 to 140 Gy was delivered to the target point with a single 4-mm isocenter. Patients were followed clinically and with neuroimaging studies. Pain relief was scored as excellent (75-100%), good (50-75%), poor (25-50%); or none (0-25%). Follow up ranged from 6 to 53 months. There were no GKS-related complications. Two patients died of unrelated medical illnesses but had good or excellent pain relief until death. One patient continues to survive with 44 months follow up and no decrease in pain intensity, but with a decreased area of pain. Combined GKS of the centromedian nucleus and trigeminal nerve in a single treatment session is feasible and safe, and the effect was promising. A larger study is required to confirm and expand these results.

  19. Calvarial and skull base metastases: expanding the clinical utility of Gamma Knife surgery.

    PubMed

    Kotecha, Rupesh; Angelov, Lilyana; Barnett, Gene H; Reddy, Chandana A; Suh, John H; Murphy, Erin S; Neyman, Gennady; Chao, Samuel T

    2014-12-01

    Traditionally, the treatment of choice for patients with metastases to the calvaria or skull base has been conventional radiation therapy. Because patients with systemic malignancies are also at risk for intracranial metastases, the utility of Gamma Knife surgery (GKS) for these patients has been explored to reduce excess radiation exposure to the perilesional brain parenchyma. The purpose of this study was to report the efficacy of GKS for the treatment of calvarial metastases and skull base lesions. The authors performed a retrospective chart review of 21 patients with at least 1 calvarial or skull base metastatic lesion treated with GKS during 2001-2013. For 7 calvarial lesions, a novel technique, in which a bolus was placed over the treatment site, was used. For determination of local control or disease progression, radiation therapy data were examined and posttreatment MR images and oncology records were reviewed. Survival times from the date of procedure were estimated by using Kaplan-Meier analyses. The median patient age at treatment was 57 years (range 29-84 years). A total of 19 (90%) patients received treatment for single lesions, 1 patient received treatment for 3 lesions, and 1 patient received treatment for 4 lesions. The most common primary tumor was breast cancer (24% of patients). Per lesion, the median clinical and radiographic follow-up times were 10.3 months (range 0-71.9 months) and 7.1 months (range 0-61.3 months), respectively. Of the 26 lesions analyzed, 14 (54%) were located in calvarial bones and 12 (46%) were located in the skull base. The median lesion volume was 5.3 cm(3) (range 0.3-55.6 cm(3)), and the median prescription margin dose was 15 Gy (range 13-24 Gy). The median overall survival time for all patients was 35.9 months, and the 1-year local control rate was 88.9% (95% CI 74.4%-100%). Local control rates did not differ between lesions treated with the bolus technique and those treated with traditional methods or between calvarial

  20. Gamma Knife radiosurgery for large vestibular schwannomas greater than 3 cm in diameter.

    PubMed

    Huang, Cheng-Wei; Tu, Hsien-Tang; Chuang, Chun-Yi; Chang, Cheng-Siu; Chou, Hsi-Hsien; Lee, Ming-Tsung; Huang, Chuan-Fu

    2018-05-01

    OBJECTIVE Stereotactic radiosurgery (SRS) is an important alternative management option for patients with small- and medium-sized vestibular schwannomas (VSs). Its use in the treatment of large tumors, however, is still being debated. The authors reviewed their recent experience to assess the potential role of SRS in larger-sized VSs. METHODS Between 2000 and 2014, 35 patients with large VSs, defined as having both a single dimension > 3 cm and a volume > 10 cm 3 , underwent Gamma Knife radiosurgery (GKRS). Nine patients (25.7%) had previously undergone resection. The median total volume covered in this group of patients was 14.8 cm 3 (range 10.3-24.5 cm 3 ). The median tumor margin dose was 11 Gy (range 10-12 Gy). RESULTS The median follow-up duration was 48 months (range 6-156 months). All 35 patients had regular MRI follow-up examinations. Twenty tumors (57.1%) had a volume reduction of greater than 50%, 5 (14.3%) had a volume reduction of 15%-50%, 5 (14.3%) were stable in size (volume change < 15%), and 5 (14.3%) had larger volumes (all of these lesions were eventually resected). Four patients (11.4%) underwent resection within 9 months to 6 years because of progressive symptoms. One patient (2.9%) had open surgery for new-onset intractable trigeminal neuralgia at 48 months after GKRS. Two patients (5.7%) who developed a symptomatic cyst underwent placement of a cystoperitoneal shunt. Eight (66%) of 12 patients with pre-GKRS trigeminal sensory dysfunction had hypoesthesia relief. One hemifacial spasm completely resolved 3 years after treatment. Seven patients with facial weakness experienced no deterioration after GKRS. Two of 3 patients with serviceable hearing before GKRS deteriorated while 1 patient retained the same level of hearing. Two patients improved from severe hearing loss to pure tone audiometry less than 50 dB. The authors found borderline statistical significance for post-GKRS tumor enlargement for later resection (p = 0.05, HR 9.97, CI 0

  1. Assessment of ambient gamma dose rate around a prospective uranium mining area of South India - A comparative study of dose by direct methods and soil radioactivity measurements

    NASA Astrophysics Data System (ADS)

    Karunakara, N.; Yashodhara, I.; Sudeep Kumara, K.; Tripathi, R. M.; Menon, S. N.; Kadam, S.; Chougaonkar, M. P.

    Indoor and outdoor gamma dose rates were evaluated around a prospective uranium mining region - Gogi, South India through (i) direct measurements using a GM based gamma dose survey meter, (ii) integrated measurement days using CaSO4:Dy based thermo luminescent dosimeters (TLDs), and (iii) analyses of 273 soil samples for 226Ra, 232Th, and 40K activity concentration using HPGe gamma spectrometry. The geometric mean values of indoor and outdoor gamma dose rates were 104 nGy h-1 and 97 nGy h-1, respectively with an indoor to outdoor dose ratio of 1.09. The gamma dose rates and activity concentrations of 226Ra, 232Th, and 40K varied significantly within a small area due to the highly localized mineralization of the elements. Correlation study showed that the dose estimated from the soil radioactivity is better correlated with that measured directly using the portable survey meter, when compared to that obtained from TLDs. This study showed that in a region having localized mineralization in situ measurements using dose survey meter provide better representative values of gamma dose rates.

  2. Dose and dose rate effects of whole-body gamma-irradiation: I. Lymphocytes and lymphoid organs

    NASA Technical Reports Server (NTRS)

    Pecaut, M. J.; Nelson, G. A.; Gridley, D. S.

    2001-01-01

    The major goal of part I of this study was to compare varying doses and dose rates of whole-body gamma-radiation on lymphoid cells and organs. C57BL/6 mice (n = 75) were exposed to 0, 0.5, 1.5, and 3.0 Gy gamma-rays (60Co) at 1 cGy/min (low-dose rate, LDR) and 80 cGy/min (high-dose rate, HDR) and euthanized 4 days later. A significant dose-dependent loss of spleen mass was observed with both LDR and HDR irradiation; for the thymus this was true only with HDR. Decreasing leukocyte and lymphocyte numbers occurred with increasing dose in blood and spleen at both dose rates. The numbers (not percentages) of CD3+ T lymphocytes decreased in the blood in a dose-dependent manner at both HDR and LDR. Splenic T cell counts decreased with dose only in HDR groups; percentages increased with dose at both dose rates. Dose-dependent decreases occurred in CD4+ T helper and CD8+ T cytotoxic cell counts at HDR and LDR. In the blood the percentages of CD4+ cells increased with increasing dose at both dose rates, whereas in the spleen the counts decreased only in the HDR groups. The percentages of the CD8+ population remained stable in both blood and spleen. CD19+ B cell counts and percentages in both compartments declined markedly with increasing HDR and LDR radiation. NK1.1+ natural killer cell numbers and proportions remained relatively stable. Overall, these data indicate that the observed changes were highly dependent on the dose, but not dose rate, and that cells in the spleen are more affected by dose rate than those in blood. The results also suggest that the response of lymphocytes in different body compartments may be variable.

  3. Gamma irradiator dose mapping simulation using the MCNP code and benchmarking with dosimetry.

    PubMed

    Sohrabpour, M; Hassanzadeh, M; Shahriari, M; Sharifzadeh, M

    2002-10-01

    The Monte Carlo transport code, MCNP, has been applied in simulating dose rate distribution in the IR-136 gamma irradiator system. Isodose curves, cumulative dose values, and system design data such as throughputs, over-dose-ratios, and efficiencies have been simulated as functions of product density. Simulated isodose curves, and cumulative dose values were compared with dosimetry values obtained using polymethyle-methacrylate, Fricke, ethanol-chlorobenzene, and potassium dichromate dosimeters. The produced system design data were also found to agree quite favorably with those of the system manufacturer's data. MCNP has thus been found to be an effective transport code for handling of various dose mapping excercises for gamma irradiators.

  4. Low-dose radiation modifies skin response to acute gamma-rays and protons.

    PubMed

    Mao, Xiao Wen; Pecaut, Michael J; Cao, Jeffrey D; Moldovan, Maria; Gridley, Daila S

    2013-01-01

    The goal of the present study was to obtain pilot data on the effects of protracted low-dose/low-dose-rate (LDR) γ-rays on the skin, both with and without acute gamma or proton irradiation (IR). Six groups of C57BL/6 mice were examined: a) 0 Gy control, b) LDR, c) Gamma, d) LDR+Gamma, e) Proton, and f) LDR+Proton. LDR radiation was delivered to a total dose of 0.01 Gy (0.03 cGy/h), whereas the Gamma and Proton groups received 2 Gy (0.9 Gy/min and 1.0 Gy/min, respectively). Assays were performed 56 days after exposure. Skin samples from all irradiated groups had activated caspase-3, indicative of apoptosis. The significant (p<0.05) increases in immunoreactivity in the Gamma and Proton groups were not present when LDR pre-exposure was included. However, the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay for DNA fragmentation and histological examination of hematoxylin and eosin-stained sections revealed no significant differences among groups, regardless of radiation regimen. The data demonstrate that caspase-3 activation initially triggered by both forms of acute radiation was greatly elevated in the skin nearly two months after whole-body exposure. In addition, LDR γ-ray priming ameliorated this response.

  5. Gamma and neutrino radiation dose from gamma ray bursts and nearby supernovae.

    PubMed

    Karam, P Andrew

    2002-04-01

    Supernovae and gamma ray bursts are exceptionally powerful cosmic events that occur randomly in space and time in our galaxy. Their potential to produce very high radiation levels has been discussed, along with speculation that they may have caused mass extinctions noted from the fossil record. It is far more likely that they have produced radiation levels that, while not lethal, are genetically significant, and these events may have influenced the course of evolution and the manner in which organisms respond to radiation insult. Finally, intense gamma radiation exposure from these events may influence the ability of living organisms to travel through space. Calculations presented in this paper suggest that supernovae and gamma ray bursts are likely to produce sea-level radiation exposures of about I Gy with a mean interval of about five million years and sea-level radiation exposures of about 0.2 Gy every million years. Comets and meteors traveling through space would receive doses in excess of 10 Gy at a depth of 0.02 m at mean intervals of 4 and 156 million years, respectively. This may place some constraints on the ability of life to travel through space either between planets or between planetary systems. Calculations of radiation dose from neutrino radiation are presented and indicate that this is not a significant source of radiation exposure for even extremely close events for the expected neutrino spectrum from these events.

  6. Dose response and repair kinetics of gamma-H2AX foci induced by in vitro irradiation of whole blood and T-lymphocytes with X- and gamma-radiation.

    PubMed

    Beels, Laurence; Werbrouck, Joke; Thierens, Hubert

    2010-09-01

    Dose response and repair kinetics of phosphorylated histone H2A isoform X (gamma-H2AX) foci in T-lymphocytes were investigated in the low-dose range after in vitro irradiation of whole blood and T-lymphocytes with 100 kVp X-rays and (60)Co gamma-rays. Whole blood or isolated T-lymphocytes were irradiated in vitro and gamma-H2AX foci were scored. Dose response was determined in the 0-500 mGy dose range. Foci kinetics were studied at doses of 5 and 200 mGy up to 24 h post-irradiation. After X-irradiation, the dose response for whole blood shows a biphasic behaviour with a low-dose hypersensitivity, which is less pronounced for isolated T-lymphocytes. In contrast, gamma-radiation shows a linear dose response for both irradiation conditions. Concerning repair kinetics, delayed repair was found after X-ray whole blood irradiation (5 and 200 mGy) with 40% of the foci persisting 24 h post-irradiation. This number of foci is reduced to 10% after irradiation of isolated T-lymphocytes with 200 mGy X-rays. On the contrary, gamma-H2AX foci are reduced to background levels 24 h post-irradiation with 200 mGy (60)Co gamma-rays. gamma-H2AX foci response and repair kinetics depend on irradiation conditions and radiation quality, possibly linked to Bystander response.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lowell, Dot; Tatter, Stephen B.; Bourland, J. Daniel

    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 incidencemore » 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.« less

  8. Monte Carlo and experimental determination of correction factors for gamma knife perfexion small field dosimetry measurements

    NASA Astrophysics Data System (ADS)

    Zoros, E.; Moutsatsos, A.; Pappas, E. P.; Georgiou, E.; Kollias, G.; Karaiskos, P.; Pantelis, E.

    2017-09-01

    Detector-, field size- and machine-specific correction factors are required for precise dosimetry measurements in small and non-standard photon fields. In this work, Monte Carlo (MC) simulation techniques were used to calculate the k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} and k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors for a series of ionization chambers, a synthetic microDiamond and diode dosimeters, used for reference and/or output factor (OF) measurements in the Gamma Knife Perfexion photon fields. Calculations were performed for the solid water (SW) and ABS plastic phantoms, as well as for a water phantom of the same geometry. MC calculations for the k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors in SW were compared against corresponding experimental results for a subset of ionization chambers and diode detectors. Reference experimental OF data were obtained through the weighted average of corresponding measurements using TLDs, EBT-2 films and alanine pellets. k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} values close to unity (within 1%) were calculated for most of ionization chambers in water. Greater corrections of up to 6.0% were observed for chambers with relatively large air-cavity dimensions and steel central electrode. A phantom correction of 1.006 and 1.024 (breaking down to 1.014 from the ABS sphere and 1.010 from the accompanying ABS phantom adapter) were calculated for the SW and ABS phantoms, respectively, adding up to k{{Qmsr},{{Q}0}}{{fmsr},{{f}ref}} corrections in water. Both measurements and MC calculations for the diode and microDiamond detectors resulted in lower than unit k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} correction factors, due to their denser sensitive volume and encapsulation materials. In comparison, higher than unit k{{Qclin},{{Q}msr}}{{fclin},{{f}msr}} results for the ionization chambers suggested field size depended dose underestimations (being significant for the 4 mm field), with magnitude depending on the combination of

  9. Dose and dose rate extrapolation factors for malignant and non-malignant health endpoints after exposure to gamma and neutron radiation.

    PubMed

    Tran, Van; Little, Mark P

    2017-11-01

    Murine experiments were conducted at the JANUS reactor in Argonne National Laboratory from 1970 to 1992 to study the effect of acute and protracted radiation dose from gamma rays and fission neutron whole body exposure. The present study reports the reanalysis of the JANUS data on 36,718 mice, of which 16,973 mice were irradiated with neutrons, 13,638 were irradiated with gamma rays, and 6107 were controls. Mice were mostly Mus musculus, but one experiment used Peromyscus leucopus. For both types of radiation exposure, a Cox proportional hazards model was used, using age as timescale, and stratifying on sex and experiment. The optimal model was one with linear and quadratic terms in cumulative lagged dose, with adjustments to both linear and quadratic dose terms for low-dose rate irradiation (<5 mGy/h) and with adjustments to the dose for age at exposure and sex. After gamma ray exposure there is significant non-linearity (generally with upward curvature) for all tumours, lymphoreticular, respiratory, connective tissue and gastrointestinal tumours, also for all non-tumour, other non-tumour, non-malignant pulmonary and non-malignant renal diseases (p < 0.001). Associated with this the low-dose extrapolation factor, measuring the overestimation in low-dose risk resulting from linear extrapolation is significantly elevated for lymphoreticular tumours 1.16 (95% CI 1.06, 1.31), elevated also for a number of non-malignant endpoints, specifically all non-tumour diseases, 1.63 (95% CI 1.43, 2.00), non-malignant pulmonary disease, 1.70 (95% CI 1.17, 2.76) and other non-tumour diseases, 1.47 (95% CI 1.29, 1.82). However, for a rather larger group of malignant endpoints the low-dose extrapolation factor is significantly less than 1 (implying downward curvature), with central estimates generally ranging from 0.2 to 0.8, in particular for tumours of the respiratory system, vasculature, ovary, kidney/urinary bladder and testis. For neutron exposure most endpoints, malignant

  10. SU-E-T-397: Evaluation of Planned Dose Distributions by Monte Carlo (0.5%) and Ray Tracing Algorithm for the Spinal Tumors with CyberKnife

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cho, H; Brindle, J; Hepel, J

    2015-06-15

    Purpose: To analyze and evaluate dose distribution between Ray Tracing (RT) and Monte Carlo (MC) algorithms of 0.5% uncertainty on a critical structure of spinal cord and gross target volume and planning target volume. Methods: Twenty four spinal tumor patients were treated with stereotactic body radiotherapy (SBRT) by CyberKnife in 2013 and 2014. The MC algorithm with 0.5% of uncertainty is used to recalculate the dose distribution for the treatment plan of the patients using the same beams, beam directions, and monitor units (MUs). Results: The prescription doses are uniformly larger for MC plans than RT except one case. Upmore » to a factor of 1.19 for 0.25cc threshold volume and 1.14 for 1.2cc threshold volume of dose differences are observed for the spinal cord. Conclusion: The MC recalculated dose distributions are larger than the original MC calculations for the spinal tumor cases. Based on the accuracy of the MC calculations, more radiation dose might be delivered to the tumor targets and spinal cords with the increase prescription dose.« less

  11. Neutron and gamma-ray dose-rates from the Little Boy replica

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Plassmann, E.A.; Pederson, R.A.

    1984-01-01

    We report dose-rate information obtained at many locations in the near vicinity of, and at distances out to 0.64 km from, the Little Boy replica while it was operated as a critical assembly. The measurements were made with modified conventional dosimetry instruments that used an Anderson-Braun detector for neutrons and a Geiger-Mueller tube for gamma rays with suitable electronic modules to count particle-induced pulses. Thermoluminescent dosimetry methods provide corroborative data. Our analysis gives estimates of both neutron and gamma-ray relaxation lengths in air for comparison with earlier calculations. We also show the neutron-to-gamma-ray dose ratio as a function of distancemore » from the replica. Current experiments and further data analysis will refine these results. 7 references, 8 figures.« less

  12. 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,…

  13. Development of a high sensitivity pinhole type gamma camera using semiconductors for low dose rate fields

    NASA Astrophysics Data System (ADS)

    Ueno, Yuichiro; Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi; Fujishima, Yasutake; Yoshida, Akira; Umegaki, Kikuo

    2018-06-01

    We developed a pinhole type gamma camera, using a compact detector module of a pixelated CdTe semiconductor, which has suitable sensitivity and quantitative accuracy for low dose rate fields. In order to improve the sensitivity of the pinhole type semiconductor gamma camera, we adopted three methods: a signal processing method to set the discriminating level lower, a high sensitivity pinhole collimator and a smoothing image filter that improves the efficiency of the source identification. We tested basic performances of the developed gamma camera and carefully examined effects of the three methods. From the sensitivity test, we found that the effective sensitivity was about 21 times higher than that of the gamma camera for high dose rate fields which we had previously developed. We confirmed that the gamma camera had sufficient sensitivity and high quantitative accuracy; for example, a weak hot spot (0.9 μSv/h) around a tree root could be detected within 45 min in a low dose rate field test, and errors of measured dose rates with point sources were less than 7% in a dose rate accuracy test.

  14. Computed radiography as a gamma ray detector—dose response and applications

    NASA Astrophysics Data System (ADS)

    O'Keeffe, D. S.; McLeod, R. W.

    2004-08-01

    Computed radiography (CR) can be used for imaging the spatial distribution of photon emissions from radionuclides. Its wide dynamic range and good response to medium energy gamma rays reduces the need for long exposure times. Measurements of small doses can be performed without having to pre-sensitize the computed radiography plates via an x-ray exposure, as required with screen-film systems. Cassette-based Agfa MD30 and Kodak GP25 CR plates were used in applications involving the detection of gamma ray emissions from technetium-99m and iodine-131. Cassette entrance doses as small as 1 µGy (140 keV gamma rays) produce noisy images, but the images are suitable for applications such as the detection of breaks in radiation protection barriers. A consequence of the gamma ray sensitivity of CR plates is the possibility that some nuclear medicine patients may fog their x-rays if the x-ray is taken soon after their radiopharmaceutical injection. The investigation showed that such fogging is likely to be diffuse.

  15. Radon survey and soil gamma doses in primary schools of Batman, Turkey.

    PubMed

    Damla, Nevzat; Aldemir, Kamuran

    2014-06-01

    A survey was conducted to evaluate levels of indoor radon and gamma doses in 42 primary schools located in Batman, southeastern Anatolia, Turkey. Indoor radon measurements were carried out using CR-39 solid-state nuclear track detector-based radon dosimeters. The overall mean annual (222)Rn activity in the surveyed area was found to be 49 Bq m(-3) (equivalent to an annual effective dose of 0.25 mSv). However, in one of the districts (Besiri) the maximum radon value turned out to be 307 Bq m(-3). The estimated annual effective doses are less than the recommended action level (3-10 mSv). It is found that the radon concentration decreases with increasing floor number. The concentrations of natural and artificial radioisotopes were determined using gamma-ray spectroscopy for soil samples collected in close vicinity of the studied schools. The mean gamma activity concentrations in the soil samples were 31, 25, 329 and 12 Bq kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, respectively. The radiological parameters such as the absorbed dose rate in air and the annual effective dose equivalent were calculated. These radiological parameters were evaluated and compared with the internationally recommended values.

  16. Dose responses for adaption to low doses of (60)Co gamma rays and (3)H beta particles in normal human fibroblasts.

    PubMed

    Broome, E J; Brown, D L; Mitchel, R E J

    2002-08-01

    The dose response for adaption to radiation at low doses was compared in normal human fibroblasts (AG1522) exposed to either (60)Co gamma rays or (3)H beta particles. Cells were grown in culture to confluence and exposed at either 37 degrees C or 0 degrees C to (3)H beta-particle or (60)Co gamma-ray adapting doses ranging from 0.1 mGy to 500 mGy. These cells, and unexposed control cells, were allowed to adapt during a fixed 3-h, 37 degrees C incubation prior to a 4-Gy challenge dose of (60)Co gamma rays. Adaption was assessed by measuring micronucleus frequency in cytokinesis-blocked, binucleate cells. No adaption was detected in cells exposed to (60)Co gamma radiation at 37 degrees C after a dose of 0.1 mGy given at a low dose rate or to 500 mGy given at a high dose rate. However, low-dose-rate exposure (1-3 mGy/min) to any dose between 1 and 500 mGy from either radiation, delivered at either temperature, caused cells to adapt and reduced the micronucleus frequency that resulted from the subsequent 4-Gy exposure. Within this dose range, the magnitude of the reduction was the same, regardless of the dose or radiation type. These results demonstrate that doses as low as (on average) about one track per cell (1 mGy) produce the same maximum adaptive response as do doses that deposit many tracks per cell, and that the two radiations were not different in this regard. Exposure at a temperature where metabolic processes, including DNA repair, were inactive (0 degrees C) did not alter the result, indicating that the adaptive response is not sensitive to changes in the accumulation of DNA damage within this range. The results also show that the RBE for low doses of tritium beta-particle radiation is 1, using adaption as the end point.

  17. 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 surgical...

  18. Gamma Knife surgery for arteriovenous malformations in the brain: integration of time-resolved contrast-enhanced magnetic resonance angiography into dosimetry planning. Technical note.

    PubMed

    Taschner, Christian A; Le Thuc, Vianney; Reyns, Nicolas; Gieseke, Juergen; Gauvrit, Jean-Yves; Pruvo, Jean-Pierre; Leclerc, Xavier

    2007-10-01

    The aim of this study was to develop an algorithm for the integration of time-resolved contrast-enhanced magnetic resonance (MR) angiography into dosimetry planning for Gamma Knife surgery (GKS) of arteriovenous malformations (AVMs) in the brain. Twelve patients harboring brain AVMs referred for GKS underwent intraarterial digital subtraction (DS) angiography and time-resolved MR angiography while wearing an externally applied cranial stereotactic frame. Time-resolved MR angiography was performed on a 1.5-tesla MR unit (Achieva, Philips Medical Systems) using contrast-enhanced 3D fast field echo sequencing with stochastic central k-space ordering. Postprocessing with interactive data language (Research Systems, Inc.) produced hybrid data sets containing dynamic angiographic information and the MR markers necessary for stereotactic transformation. Image files were sent to the Leksell GammaPlan system (Elekta) for dosimetry planning. Stereotactic transformation of the hybrid data sets containing the time-resolved MR angiography information with automatic detection of the MR markers was possible in all 12 cases. The stereotactic coordinates of vascular structures predefined from time-resolved MR angiography matched with DS angiography data in all cases. In 10 patients dosimetry planning could be performed based on time-resolved MR angiography data. In two patients, time-resolved MR angiography data alone were considered insufficient. The target volumes showed a notable shift of centers between modalities. Integration of time-resolved MR angiography data into the Leksell GammaPlan system for patients with brain AVMs is feasible. The proposed algorithm seems concise and sufficiently robust for clinical application. The quality of the time-resolved MR angiography sequencing needs further improvement.

  19. Dosimetric verification of stereotactic radiosurgery/stereotactic radiotherapy dose distributions using Gafchromic EBT3

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cusumano, Davide, E-mail: davide.cusumano@unimi.it; Fumagalli, Maria L.; Marchetti, Marcello

    2015-10-01

    Aim of this study is to examine the feasibility of using the new Gafchromic EBT3 film in a high-dose stereotactic radiosurgery and radiotherapy quality assurance procedure. Owing to the reduced dimensions of the involved lesions, the feasibility of scanning plan verification films on the scanner plate area with the best uniformity rather than using a correction mask was evaluated. For this purpose, signal values dispersion and reproducibility of film scans were investigated. Uniformity was then quantified in the selected area and was found to be within 1.5% for doses up to 8 Gy. A high-dose threshold level for analyses usingmore » this procedure was established evaluating the sensitivity of the irradiated films. Sensitivity was found to be of the order of centiGray for doses up to 6.2 Gy and decreasing for higher doses. The obtained results were used to implement a procedure comparing dose distributions delivered with a CyberKnife system to planned ones. The procedure was validated through single beam irradiation on a Gafchromic film. The agreement between dose distributions was then evaluated for 13 patients (brain lesions, 5 Gy/die prescription isodose ~80%) using gamma analysis. Results obtained using Gamma test criteria of 5%/1 mm show a pass rate of 94.3%. Gamma frequency parameters calculation for EBT3 films showed to strongly depend on subtraction of unexposed film pixel values from irradiated ones. In the framework of the described dosimetric procedure, EBT3 films proved to be effective in the verification of high doses delivered to lesions with complex shapes and adjacent to organs at risk.« less

  20. Gamma-Ray Dose Measurement with Radio-Photoluminescence Glass Dosimeter in Mixed Radiation Field for BNCT

    NASA Astrophysics Data System (ADS)

    Hiramatsu, K.; Yoshihashi, S.; Kusaka, S.; Sato, F.; Hoashi, E.; Murata, I.

    2017-09-01

    Accelerator based neutron sources (ABNS) are being developed as the next generation neutron irradiation system for BNCT. From the ABNS, unnecessary gamma-rays will be generated by neutron capture reactions, as well as fast neutrons. To control the whole-body radiation dose to the patient, measurement of gamma-ray dose in the irradiation room is necessary. In this study, the objective is to establish a method to measure gamma-ray dose separately in a neutron/gamma mixed field by using RPL glass dosimeter. For this purpose, we proposed a lead filter method which uses a pair of RPL glasses with and without a lead filter outside. In order to realize this method, the basic characteristics of glass dosimeter was verified in the gamma-ray field, before adapting it in the mixture field. From the result of the experiment using the lead filter, the simulation result especially for the case with a lead filter overestimated the absorbed does obtained from measurement. We concluded that the reason of the discrepancy is caused by existence of gradient of the dose distribution in the glass, and the difference of sensitivity to low-energy photon between measurement and theory.

  1. Long-term safety and efficacy of stereotactic radiosurgery for vestibular schwannomas: evaluation of 440 patients more than 10 years after treatment with Gamma Knife surgery.

    PubMed

    Hasegawa, Toshinori; Kida, Yoshihisa; Kato, Takenori; Iizuka, Hiroshi; Kuramitsu, Shunichiro; Yamamoto, Takashi

    2013-03-01

    Object Little is known about long-term outcomes, including tumor control and adverse radiation effects, in patients harboring vestibular schwannomas (VSs) treated with stereotactic radiosurgery > 10 years previously. The aim of this study was to confirm whether Gamma Knife surgery (GKS) for VSs continues to be safe and effective > 10 years after treatment. Methods A total of 440 patients with VS (including neurofibromatosis Type 2) treated with GKS between May 1991 and December 2000 were evaluable. Of these, 347 patients (79%) underwent GKS as an initial treatment and 93 (21%) had undergone prior resection. Three hundred fifty-eight patients (81%) had a solid tumor and 82 (19%) had a cystic tumor. The median tumor volume was 2.8 cm(3) and the median marginal dose was 12.8 Gy. Results The median follow-up period was 12.5 years. The actuarial 5- and ≥ 10-year progression-free survival was 93% and 92%, respectively. No patient developed treatment failure > 10 years after treatment. According to multivariate analysis, significant factors related to worse progression-free survival included brainstem compression with a deviation of the fourth ventricle (p < 0.0001), marginal dose ≤ 13 Gy (p = 0.01), prior treatment (p = 0.02), and female sex (p = 0.02). Of 287 patients treated at a recent optimum dose of ≤ 13 Gy, 3 (1%) developed facial palsy, including 2 with transient palsy and 1 with persistent palsy after a second GKS, and 3 (1%) developed facial numbness, including 2 with transient and 1 with persistent facial numbness. The actuarial 10-year facial nerve preservation rate was 97% in the high marginal dose group (> 13 Gy) and 100% in the low marginal dose group (≤ 13 Gy). Ten patients (2.3%) developed delayed cyst formation. One patient alone developed malignant transformation, indicating an incidence of 0.3%. Conclusions In this study GKS was a safe and effective treatment for the majority of patients followed > 10 years after treatment. Special attention

  2. Development of autonomous gamma dose logger for environmental monitoring

    NASA Astrophysics Data System (ADS)

    Jisha, N. V.; Krishnakumar, D. N.; Surya Prakash, G.; Kumari, Anju; Baskaran, R.; Venkatraman, B.

    2012-03-01

    Continuous monitoring and archiving of background radiation levels in and around the nuclear installation is essential and the data would be of immense use during analysis of any untoward incidents. A portable Geiger Muller detector based autonomous gamma dose logger (AGDL) for environmental monitoring is indigenously designed and developed. The system operations are controlled by microcontroller (AT89S52) and the main features of the system are software data acquisition, real time LCD display of radiation level, data archiving at removable compact flash card. The complete system operates on 12 V battery backed up by solar panel and hence the system is totally portable and ideal for field use. The system has been calibrated with Co-60 source (8.1 MBq) at various source-detector distances. The system is field tested and performance evaluation is carried out. This paper covers the design considerations of the hardware, software architecture of the system along with details of the front-end operation of the autonomous gamma dose logger and the data file formats. The data gathered during field testing and inter comparison with GammaTRACER are also presented in the paper. AGDL has shown excellent correlation with energy fluence monitor tuned to identify 41Ar, proving its utility for real-time plume tracking and source term estimation.

  3. Dosimetric evaluation of lithium carbonate (Li2CO3) as a dosemeter for gamma-radiation dose measurements.

    PubMed

    Popoca, R; Ureña-Núñez, F

    2009-06-01

    This work reports the possibility of using lithium carbonate as a dosimetric material for gamma-radiation measurements. Carboxi-radical ions, CO(2)(-) and CO(3)(-), arise from the gamma irradiation of Li(2)CO(3), and these radical ions can be quantified by electron paramagnetic resonance (EPR) spectrometry. The EPR-signal response of gamma-irradiated lithium carbonate has been investigated to determine some dosimetric characteristics such as: peak-to-peak signal intensity versus gamma dose received, zero-dose response, signal fading, signal repeatability, batch homogeneity, dose rate effect and stability at different environmental conditions. Using the conventional peak-to-peak method of stable ion radicals, it is concluded that lithium carbonate could be used as a gamma dosemeter in the range of 3-100 Gy.

  4. Evaluation of gamma dose effect on PIN photodiode using analytical model

    NASA Astrophysics Data System (ADS)

    Jafari, H.; Feghhi, S. A. H.; Boorboor, S.

    2018-03-01

    The PIN silicon photodiodes are widely used in the applications which may be found in radiation environment such as space mission, medical imaging and non-destructive testing. Radiation-induced damage in these devices causes to degrade the photodiode parameters. In this work, we have used new approach to evaluate gamma dose effects on a commercial PIN photodiode (BPX65) based on an analytical model. In this approach, the NIEL parameter has been calculated for gamma rays from a 60Co source by GEANT4. The radiation damage mechanisms have been considered by solving numerically the Poisson and continuity equations with the appropriate boundary conditions, parameters and physical models. Defects caused by radiation in silicon have been formulated in terms of the damage coefficient for the minority carriers' lifetime. The gamma induced degradation parameters of the silicon PIN photodiode have been analyzed in detail and the results were compared with experimental measurements and as well as the results of ATLAS semiconductor simulator to verify and parameterize the analytical model calculations. The results showed reasonable agreement between them for BPX65 silicon photodiode irradiated by 60Co gamma source at total doses up to 5 kGy under different reverse voltages.

  5. 131 iodine gamma dose determination in the thyroid gland using two geometrical shapes: a comparative study

    NASA Astrophysics Data System (ADS)

    Betka, A.; Bentabet, A.; Azbouche, A.; Fenineche, N.; Adjiri, A.; Dib, A.

    2015-05-01

    In order to study the internal gamma dose, we used a Monte Carlo code ‘Penelope’ simulation with two geometrical models (cylindrical and spherical). The deposited energy was determined via the loss of energy calculated from the quantum theory for inelastic collisions based on the first-order (plane-wave) Born approximation for charged particles with individual atoms and molecules. Our results show that the cylindrical geometry is more suitable for carrying out such a study. Moreover, we developed an analytical expression for the 131 iodine gamma dose (the energy deposited per photon absorbed dose). This latter could be considered as an important tool for evaluating the gamma dose without going through stochastic models.

  6. Analysis of 2000 cases treated with gamma knife surgery: validating eligibility criteria for a prospective multi-institutional study of stereotactic radiosurgery alone for treatment of patients with 1-10 brain metastases (JLGK0901) in Japan

    PubMed Central

    Higuchi, Yoshinori; Nagano, Osamu; Sato, Yasunori; Yamamoto, Masaaki; Ono, Junichi; Saeki, Naokatsu; Miyakawa, Akifumi; Hirai, Tatsuo

    2012-01-01

    Objective The Japan Leksell Gamma Knife (JLGK) Society has conducted a prospective multi-institute study (JLGK0901, UNIN000001812) for selected patients in order to prove the effectiveness of stereotactic radiosurgery (SRS) alone using the gamma knife (GK) for 1-10 brain lesions. Herein, we verify the validity of 5 major patient selection criteria for the JLGK0901 trial. Materials and Methods Between 1998 and 2010, 2246 consecutive cases with 10352 brain metastases treated with GK were analyzed to determine the validity of the following 5 major JLGK0901 criteria; 1) 1-10 brain lesions, 2) less than 10 cm3 volume of the largest tumor, 3) no more than 15 cm3 total tumor volume, 4) no cerebrospinal fluid (CSF) dissemination, 5) Karnofsky performance status (KPS) score ≥70. Results For cases with >10 brain metastases, salvage treatments for new lesions were needed more frequently. The tumor control rate for lesions larger than 10 cm3 was significantly lower than that of tumors <10 cm3. Overall, neurological and qualitative survivals (OS, NS, QS) of cases with >15 cm3 total tumor volume or positive magnetic resonance imaging findings of CSF were significantly poorer. Outcomes in cases with KPS <70 were significantly poorer in terms of OS. Conclusion Our retrospective results of 2246 GK-treated cases verified the validity of the 5 major JLGK0901 criteria. The inclusion criteria for the JLGK0901 study are appearently good indications for SRS. PMID:29296339

  7. Indoor terrestrial gamma dose rate mapping in France: a case study using two different geostatistical models.

    PubMed

    Warnery, E; Ielsch, G; Lajaunie, C; Cale, E; Wackernagel, H; Debayle, C; Guillevic, J

    2015-01-01

    Terrestrial gamma dose rates show important spatial variations in France. Previous studies resulted in maps of arithmetic means of indoor terrestrial gamma dose rates by "departement" (French district). However, numerous areas could not be characterized due to the lack of data. The aim of our work was to obtain more precise estimates of the spatial variability of indoor terrestrial gamma dose rates in France by using a more recent and complete data base and geostatistics. The study was based on the exploitation of 97,595 measurements results distributed in 17,404 locations covering all of France. Measurements were done by the Institute for Radioprotection and Nuclear Safety (IRSN) using RPL (Radio Photo Luminescent) dosimeters, exposed during several months between years 2011 and 2012 in French dentist surgeries and veterinary clinics. The data used came from dosimeters which were not exposed to anthropic sources. After removing the cosmic rays contribution in order to study only the telluric gamma radiation, it was decided to work with the arithmetic means of the time-series measurements, weighted by the time-exposure of the dosimeters, for each location. The values varied between 13 and 349 nSv/h, with an arithmetic mean of 76 nSv/h. The observed statistical distribution of the gamma dose rates was skewed to the right. Firstly, ordinary kriging was performed in order to predict the gamma dose rate on cells of 1*1 km(2), all over the domain. The second step of the study was to use an auxiliary variable in estimates. The IRSN achieved in 2010 a classification of the French geological formations, characterizing their uranium potential on the bases of geology and local measurement results of rocks uranium content. This information is georeferenced in a map at the scale 1:1,000,000. The geological uranium potential (GUP) was classified in 5 qualitative categories. As telluric gamma rays mostly come from the progenies of the (238)Uranium series present in rocks, this

  8. Optical fiber sensor for low dose gamma irradiation monitoring

    NASA Astrophysics Data System (ADS)

    de Andrés, Ana I.; Esteban, Ã.`scar; Embid, Miguel

    2016-05-01

    An optical fiber gamma ray detector is presented in this work. It is based on a Terbium doped Gadolinium Oxysulfide (Gd2O2S:Tb) scintillating powder which cover a chemically etched polymer fiber tip. This etching improves the fluorescence gathering by the optical fiber. The final diameter has been selected to fulfill the trade-off between light gathering and mechanical strength. Powder has been encapsulated inside a microtube where the fiber tip is immersed. The sensor has been irradiated with different air Kerma doses up to 2 Gy/h with a 137Cs source, and the spectral distribution of the fluorescence intensity has been recorded in a commercial grade CCD spectrometer. The obtained signal-to-noise ratio is good enough even for low doses, which has allowed to reduce the integration time in the spectrometer. The presented results show the feasibility for using low cost equipment to detect/measure ionizing radiation as gamma rays are.

  9. SU-E-T-404: Evaluation of the Effect of Spine Hardware for CyberKnife Spinal Stereotactic Radiosurgery

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yuan, J; Zhang, Y; Zheng, Y

    2015-06-15

    Purpose: Spine hardware made of high-Z materials such as titanium has the potential to affect the dose distribution around the metal rods in CyberKnife spinal stereotactic radiosurgery (SRS) treatments. The purpose of this work was to evaluate the magnitude of such effect retrospectively for clinical CyberKnife plans. Methods: The dose calculation was performed within the MultiPlan treatment planning system using the ray tracing (RT) and Monte Carlo (MC) method. A custom density model was created by extending the CT-to-Density table to titanium density of 4.5 g/cm3 with the CT number of 4095. To understand the dose perturbation caused by themore » titanium rod, a simple beam setup (7.5 mm IRIS collimator) was used to irradiate a mimic rod (5 mm) with overridden high density. Five patient spinal SRS cases were found chronologically from 2010 to 2015 in our institution. For each case, the hardware was contoured manually. The original plan was re-calculated using both RT and MC methods with and without rod density override without changing clinical beam parameters. Results: The simple beam irradiation shows that there is 10% dose increase at the interface because of electron backscattering and 7% decrease behind the rod because of photon attenuation. For actual clinical plans, the iso-dose lines and DVHs are almost identical (<2%) for calculations with and without density override for both RT and MC methods. However, there is a difference of more than 10% for D90 between RT and MC method. Conclusion: Although the dose perturbation around the metal rods can be as large as 10% for a single beam irradiation, for clinical treatments with complex beam composition the effect of spinal hardware to the PTV and spinal dose is minimal. As such, the MC dose algorithm without rod density override for CyberKnife spinal SRS is acceptable.« less

  10. Evaluation of dose delivery accuracy of gamma knife using MRI polymer gel dosimeter in an inhomogeneous phantom

    NASA Astrophysics Data System (ADS)

    Pourfallah T, A.; Alam N, Riahi; M, Allahverdi; M, Ay; M, Zahmatkesh

    2009-05-01

    Polymer gel dosimetry is still the only dosimetry method for directly measuring three-dimensional dose distributions. MRI Polymer gel dosimeters are tissue equivalent and can act as a phantom material. Because of high dose response sensitivity, the MRI was chosen as readout device. In this study dose profiles calculated with treatment-planning software (LGP) and measurements with the MR polymer gel dosimeter for single-shot irradiations were compared. A custom-built 16 cm diameter spherical plexiglas head phantom was used in this study. Inside the phantom, there is a cubic cutout for insertion of gel phantoms and another cutout for inserting the inhomogeneities. The phantoms were scanned with a 1.5T MRI (Siemens syngo MR 2004A 4VA25A) scanner. The multiple spin-echo sequence with 32 echoes was used for the MRI scans. Calibration relations between the spin-spin relaxation rate and the absorbed dose were obtained by using small cylindrical vials, which were filled with the PAGAT polymer gel from the same batch as for the spherical phantom. 1D and 2D data obtained using gel dosimeter for homogeneous and inhomogeneous phantoms were compared with dose obtained using LGP calculation. The distance between relative isodose curves obtained for homogeneous phantom and heterogeneous phantoms exceed the accepted total positioning error (>±2mm). The findings of this study indicate that dose measurement using PAGAT gel dosimeter can be used for verifying dose delivering accuracy in GK unit in presence of inhomogeneities.

  11. Radioactivity Risk Assessment of Radon and Gamma Dose at One Uranium Tailings Pond in China

    NASA Astrophysics Data System (ADS)

    Lou, Yalong; Liu, Yong; Peng, Guowen; Zhao, Guodong; Zhang, Yan; Yang, Zhu

    2018-01-01

    A year-long monitoring of gamma radiation effective dose rate and radon concentration had been done in the reservoir area of one uranium tailings pond in Hunan province (The monitoring area included indoor and outdoor area of residential buildings and workshops, tailings dam slope). Afterwards, the annual effective radiation dose of the people in that radiation environment had been calculated based on the results of monitoring, as well as a radiation risk assessment. According to the assessment, gamma radiation effective dose rate and radon concentration in the monitoring area were low, and the annual effective radiation dose was far below the international standard (30mSv), which showed that the radiation would not put the people’s health at risk. However, the annual effective radiation dose of gamma was far above that of radon in the area of uranium tailings pond; therefore, it’s advisable to take quarantine measures in in the area of uranium tailings pond to keep the surrounding residents away from unnecessary ionizing radiation.

  12. Gamma Knife radiosurgery for glossopharyngeal neuralgia: A study of 21 patients with long-term follow-up.

    PubMed

    Borius, Pierre-Yves; Tuleasca, Constantin; Muraciole, Xavier; Negretti, Laura; Schiappacasse, Luis; Dorenlot, Antoine; Marguet, Maud; Zeverino, Michele; Donnet, Anne; Levivier, Marc; Regis, Jean

    2018-03-01

    Objective Glossopharyngeal neuralgia (GPN) is a very rare condition, affecting the patient's quality of life. We report our experience in drug-resistant, idiopathic GPN, treated with Gamma Knife radiosurgery (GKRS), in terms of safety and efficiency, on a very long-term basis. Methods The study was opened, self-controlled, non-comparative and bicentric (Marseille and Lausanne University Hospitals). Patients treated with GKRS between 2003 and 2015 (models C, 4C and Perfexion) were included. A single 4-mm isocentre was positioned in the cisternal portion of the glossopharyngeal nerve, with a targeting based both on magnetic resonance imaging (MRI) and computed tomography (CT). The mean maximal dose delivered was 81.4 ± 6.7 Gy (median = 85 Gy, range = 60-90 Gy at the 100% isodose line). Results Twenty-one patients (11 women, 10 men) benefited from 25 procedures. The mean follow-up period was 5.2 ± 3 years (range = 0.9-12.1 years). Seventeen (81%) were initially pain-free after GKRS. At three months, six months and one year after radiosurgery, the percentage of patients with good outcome (BNI classes I to IIIA) was 87.6%, 100% and 81.8%, respectively. Ten cases (58.8%) from the initial pain-free ones had a recurrence, after a mean period of 13.6 ± 10.4 months (range = 3.1-36.6 months). Only three patients (14.2%) had recurrences (two for each one of them) requiring further surgeries. Three patients underwent a second GKRS procedure; one case needed a third GKRS. The former procedures were performed at 7, 17, 19 and 30 months after the first one, respectively. Furthermore, two patients needed additional interventions. At last follow-up, 17 cases (80.9%) were still pain-free without medication. The actuarial pain relief without new surgery was 83%. A transient complication (paraesthesia of the edge of the tongue) was seen in one case (4.8%). Conclusion GKRS is a valuable, minimally invasive, surgical alternative for idiopathic GPN

  13. Hard beta and gamma emissions of 124I. Impact on occupational dose in PET/CT.

    PubMed

    Kemerink, G J; Franssen, R; Visser, M G W; Urbach, C J A; Halders, S G E A; Frantzen, M J; Brans, B; Teule, G J J; Mottaghy, F M

    2011-01-01

    The hard beta and gamma radiation of 124I can cause high doses to PET/CT workers. In this study we tried to quantify this occupational exposure and to optimize radioprotection. Thin MCP-Ns thermoluminescent dosimeters suitable for measuring beta and gamma radiation were used for extremity dosimetry, active personal dosimeters for whole-body dosimetry. Extremity doses were determined during dispensing of 124I and oral administration of the activity to the patient, the body dose during all phases of the PET/CT procedure. In addition, dose rates of vials and syringes as used in clinical practice were measured. The procedure for dispensing 124I was optimized using newly developed shielding. Skin dose rates up to 100 mSv/min were measured when in contact with the manufacturer's vial containing 370 MBq of 124I. For an unshielded 5 ml syringe the positron skin dose was about seven times the gamma dose. Before optimization of the preparation of 124I, using an already reasonably safe technique, the highest mean skin dose caused by handling 370 MBq was 1.9 mSv (max. 4.4 mSv). After optimization the skin dose was below 0.2 mSv. The highly energetic positrons emitted by 124I can cause high skin doses if radioprotection is poor. Under optimized conditions occupational doses are acceptable. Education of workers is of paramount importance.

  14. RT-06GAMMA KNIFE SURGERY AFTER NAVIGATION-GUIDED ASPIRATION FOR CYSTIC METASTATIC BRAIN TUMORS

    PubMed Central

    Chiba, Yasuyoshi; Mori, Kanji; Toyota, Shingo; Kumagai, Tetsuya; Yamamoto, Shota; Sugano, Hirofumi; Taki, Takuyu

    2014-01-01

    Metastatic brain tumors over 3 cm in diameter (volume of 14.1ml) are generally considered poor candidates for Gamma Knife surgery (GKS). We retrospectively assessed the method and efficacy of GKS for large cystic metastatic brain tumors after navigation-guided aspiration under local anesthesia. From September 2007 to April 2014, 38 cystic metastatic brain tumors in 32 patients (12 males, 20 females; mean age, 63.2 years) were treated at Kansai Rosai Hospital. The patients were performed navigation-guided cyst aspiration under local anesthesia, then at the day or the next day, were performed GKS and usually discharged on the day. The methods for preventing of leptomeningeal dissemination are following: 1) puncture from the place whose cerebral thickness is 1 cm or more; 2) avoidance of Ommaya reservoir implantation; and 3) placement of absorbable gelatin sponge to the tap tract. Tumor volume, including the cystic component, decreased from 25.4 ml (range 8.7-84.7 ml) to 11.4 ml (range 2.9-36.7 ml) following aspiration; the volume reduction was approximately 51.6%. Follow-up periods in the study population ranged from 0 to 24 months (median 3.5 months). The overall median survival was 6.7 months. There was no leptomeningeal dissemination related to the aspiration. One patient experienced radiation necrosis after GKS, one patient experienced re-aspiration by failure of aspiration, and two patients experienced surgical resections and one patient experienced re-aspiration by cyst regrowth after GKS. Long-term hospitalization is not desirable for the patients with brain metastases. In japan, Long-term hospitalization is required for surgical resection or whole brain radiation therapy, but only two days hospitalization is required for GKS after navigation-guided aspiration at our hospital. This GKS after navigation-guided aspiration is more effective and less invasive than surgical resection or whole brain radiation therapy.

  15. CALCULATION OF GAMMA SPECTRA IN A PLASTIC SCINTILLATOR FOR ENERGY CALIBRATIONAND DOSE COMPUTATION.

    PubMed

    Kim, Chankyu; Yoo, Hyunjun; Kim, Yewon; Moon, Myungkook; Kim, Jong Yul; Kang, Dong Uk; Lee, Daehee; Kim, Myung Soo; Cho, Minsik; Lee, Eunjoong; Cho, Gyuseong

    2016-09-01

    Plastic scintillation detectors have practical advantages in the field of dosimetry. Energy calibration of measured gamma spectra is important for dose computation, but it is not simple in the plastic scintillators because of their different characteristics and a finite resolution. In this study, the gamma spectra in a polystyrene scintillator were calculated for the energy calibration and dose computation. Based on the relationship between the energy resolution and estimated energy broadening effect in the calculated spectra, the gamma spectra were simply calculated without many iterations. The calculated spectra were in agreement with the calculation by an existing method and measurements. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Evaluation of a new disposable silicon limbal relaxing incision knife by experienced users.

    PubMed

    Albanese, John; Dugue, Geoffrey; Parvu, Valentin; Bajart, Ann M; Lee, Edwin

    2009-12-21

    Previous research has suggested that the silicon BD Atomic Edge knife has superior performance characteristics when compared to a metal knife and performance similar to diamond knife when making various incisions. This study was designed to determine whether a silicon accurate depth knife has equivalent performance characteristics when compared to a diamond limbal relaxing incision (LRI) knife and superior performance characteristics when compared to a steel accurate depth knife when creating limbal relaxing incision. Sixty-five ophthalmic surgeons with limbal relaxing incision experience created limbal relaxing incisions in ex-vivo porcine eyes with silicon and steel accurate depth knives and diamond LRI knives. The ophthalmic surgeons rated multiple performance characteristics of the knives on Visual Analog Scales. The observed differences between the silicon knife and diamond knife were found to be insignificant. The mean ratio between the performance of the silicon knife and the diamond knife was shown to be greater than 90% (with 95% confidence). The silicon knife's mean performance was significantly higher than the performance of the steel knife for all characteristics. (p-value < .05) For experienced users, the silicon accurate depth knife was found to be equivalent in performance to the diamond LRI knife and superior to the steel accurate depth knife when making limbal relaxing incisions in ex vivo porcine eyes. Disposable silicon LRI knives may be an alternative to diamond LRI knives.

  17. Development of autonomous gamma dose logger for environmental monitoring

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jisha, N. V.; Krishnakumar, D. N.; Surya Prakash, G.

    2012-03-15

    Continuous monitoring and archiving of background radiation levels in and around the nuclear installation is essential and the data would be of immense use during analysis of any untoward incidents. A portable Geiger Muller detector based autonomous gamma dose logger (AGDL) for environmental monitoring is indigenously designed and developed. The system operations are controlled by microcontroller (AT89S52) and the main features of the system are software data acquisition, real time LCD display of radiation level, data archiving at removable compact flash card. The complete system operates on 12 V battery backed up by solar panel and hence the system ismore » totally portable and ideal for field use. The system has been calibrated with Co-60 source (8.1 MBq) at various source-detector distances. The system is field tested and performance evaluation is carried out. This paper covers the design considerations of the hardware, software architecture of the system along with details of the front-end operation of the autonomous gamma dose logger and the data file formats. The data gathered during field testing and inter comparison with GammaTRACER are also presented in the paper. AGDL has shown excellent correlation with energy fluence monitor tuned to identify {sup 41}Ar, proving its utility for real-time plume tracking and source term estimation.« less

  18. Enhancement of natural background gamma-radiation dose around uranium microparticles in the human body.

    PubMed

    Pattison, John E; Hugtenburg, Richard P; Green, Stuart

    2010-04-06

    Ongoing controversy surrounds the adverse health effects of the use of depleted uranium (DU) munitions. The biological effects of gamma-radiation arise from the direct or indirect interaction between secondary electrons and the DNA of living cells. The probability of the absorption of X-rays and gamma-rays with energies below about 200 keV by particles of high atomic number is proportional to the third to fourth power of the atomic number. In such a case, the more heavily ionizing low-energy recoil electrons are preferentially produced; these cause dose enhancement in the immediate vicinity of the particles. It has been claimed that upon exposure to naturally occurring background gamma-radiation, particles of DU in the human body would produce dose enhancement by a factor of 500-1000, thereby contributing a significant radiation dose in addition to the dose received from the inherent radioactivity of the DU. In this study, we used the Monte Carlo code EGSnrc to accurately estimate the likely maximum dose enhancement arising from the presence of micrometre-sized uranium particles in the body. We found that although the dose enhancement is significant, of the order of 1-10, it is considerably smaller than that suggested previously.

  19. Enhancement of natural background gamma-radiation dose around uranium microparticles in the human body

    PubMed Central

    Pattison, John E.; Hugtenburg, Richard P.; Green, Stuart

    2010-01-01

    Ongoing controversy surrounds the adverse health effects of the use of depleted uranium (DU) munitions. The biological effects of gamma-radiation arise from the direct or indirect interaction between secondary electrons and the DNA of living cells. The probability of the absorption of X-rays and gamma-rays with energies below about 200 keV by particles of high atomic number is proportional to the third to fourth power of the atomic number. In such a case, the more heavily ionizing low-energy recoil electrons are preferentially produced; these cause dose enhancement in the immediate vicinity of the particles. It has been claimed that upon exposure to naturally occurring background gamma-radiation, particles of DU in the human body would produce dose enhancement by a factor of 500–1000, thereby contributing a significant radiation dose in addition to the dose received from the inherent radioactivity of the DU. In this study, we used the Monte Carlo code EGSnrc to accurately estimate the likely maximum dose enhancement arising from the presence of micrometre-sized uranium particles in the body. We found that although the dose enhancement is significant, of the order of 1–10, it is considerably smaller than that suggested previously. PMID:19776147

  20. Dosimetric verification of stereotactic radiosurgery/stereotactic radiotherapy dose distributions using Gafchromic EBT3.

    PubMed

    Cusumano, Davide; Fumagalli, Maria L; Marchetti, Marcello; Fariselli, Laura; De Martin, Elena

    2015-01-01

    Aim of this study is to examine the feasibility of using the new Gafchromic EBT3 film in a high-dose stereotactic radiosurgery and radiotherapy quality assurance procedure. Owing to the reduced dimensions of the involved lesions, the feasibility of scanning plan verification films on the scanner plate area with the best uniformity rather than using a correction mask was evaluated. For this purpose, signal values dispersion and reproducibility of film scans were investigated. Uniformity was then quantified in the selected area and was found to be within 1.5% for doses up to 8 Gy. A high-dose threshold level for analyses using this procedure was established evaluating the sensitivity of the irradiated films. Sensitivity was found to be of the order of centiGray for doses up to 6.2 Gy and decreasing for higher doses. The obtained results were used to implement a procedure comparing dose distributions delivered with a CyberKnife system to planned ones. The procedure was validated through single beam irradiation on a Gafchromic film. The agreement between dose distributions was then evaluated for 13 patients (brain lesions, 5 Gy/die prescription isodose ~80%) using gamma analysis. Results obtained using Gamma test criteria of 5%/1 mm show a pass rate of 94.3%. Gamma frequency parameters calculation for EBT3 films showed to strongly depend on subtraction of unexposed film pixel values from irradiated ones. In the framework of the described dosimetric procedure, EBT3 films proved to be effective in the verification of high doses delivered to lesions with complex shapes and adjacent to organs at risk. Copyright © 2015 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

  1. Long-term outcome of gamma knife radiosurgery for metastatic brain tumors originating from lung cancer

    PubMed Central

    Bir, Shyamal C.; Ambekar, Sudheer; Bollam, Papireddy; Nanda, Anil

    2014-01-01

    Background: Gamma knife radiosurgery (GKRS) has emerged as an important treatment option for metastasis brain tumors (MBTs). However, the long-term outcome of GKRS on MBTs originating from lung carcinoma is not well understood. The treatment of MBTs derived from lung cancer with GKRS at our institution is reviewed. Methods: We performed a retrospective review (2000-2013) of 173 patients with MBTs from lung cancer who received GKRS. Out of 173 patients, 38 patients had recurrent tumors after microsurgical resection and whole brain radiotherapy (WBT). Results: GKRS in MBTs metastasized from lung carcinoma showed significant variations in tumor growth control (decreased in 79 [45.7%] patients, arrested growth in 54 [31.2%] patients, and increased tumor size in 40 [23.1%] patients). The median survival in the study population was 14 months. Overall survival after 3 years was 25%, whereas progression-free survival after 3 years was 45%. The predictive factors for improving survival in the patients with MBTs were recursive partitioning analysis (RPA) class I (P = 0.005), absence of hydrocephalus (P = 0.001), Karnofsky performance scale (KPS) >70 (P = 0.007), age ≤65 (P = 0.041), tumor size ≤3 cm (P = 0.023), controlled primary tumor (P = 0.049), and single number of MBTS (P = 0.044). Conclusion: Long-term follow-up revealed that GKRS offers a high rate of tumor control and good overall survival period in both new and recurrent patients with MBTs originating from lung carcinoma. Thus, GKRS is an effective treatment option for new patients with MBTs from lung cancer, as well as an adjuvant therapy in patients with recurrent MBTs derived from lung cancer. PMID:25289169

  2. [Research progress of needles with knife-edge for carotid cardiac syndrome].

    PubMed

    Tan, Lingqiong; Zhao, Yanling

    2015-04-01

    According to topographic anatomy, pathogenesis and by retrieving, summarizing and analyzing literature regarding needle-knife and needles with knife-edge for carotid cardiac syndrome, it is found out that clinical misdiagnosis rate of carotid cardiac syndrome is considerably high. Needle-knife and needles with knife-edge could significantly improve the clinical symptoms of carotid cardiac syndrome, showing characteristic and advantage in treatment, but it is deficient in technique standard and efficacy criteria that should be united and authoritative. Researches regarding pathogenesis of carotid cardiac syndrome are not systematic. Clinical observation regarding long-term efficacy and relapse of needle-knife and needles with knife-edge treatment is rare. It is believed that the awareness on carotid cardiac syndrome should be increased to reduce misdiagnosis; scientific and standardized technique standard and efficacy criteria should be established; systematic and comprehensive researches regarding mechanism of needle-knife and needles with knife-edge for carotid cardiac syndrome should be launched; besides, clinical discussion regarding its long-term efficacy should start to provide a better clinical guideline.

  3. No need to change the skin knife in modern arthroplasty surgery.

    PubMed

    Ottesen, C; Skovby, A; Troelsen, A; Specht, C; Friis-Møller, A; Husted, H

    2014-08-01

    Earlier studies have found varying contamination rates using separate skin and deep knives in total hip (THA) and total knee (TKA) arthroplasty surgery. Previous studies were primarily conducted in the setting of concomitant use of laminar airflow and/or plastic adhesive draping. This has lead to conflicting conclusions regarding discarding the skin knife or not. This study evaluates the prevalence of contamination of a separate skin knife using modern antiseptic technique in primary THA and TKA without laminar airflow. Three knives from each primary THA and TKA surgery in non-laminar airflow operating rooms were collected: one used for the skin, one used for deeper tissues and one control knife. A total of 831 knife blades from 277 patients were cultured 12 days. Contamination of the skin knife was found in eight patients (2.8 %), contamination of the "deep" knife in five patients (1.8 %) and contamination of the control knife in five patients (1.8 %). No patient developed an infection with 1-year follow-up. Our findings suggest a very low rate of contamination of the skin knife using modern antiseptic technique without laminar airflow and/or plastic adhesive draping and do not support the use of a separate skin knife in arthroplasty surgery.

  4. Conservative management or gamma knife radiosurgery for vestibular schwannoma: tumor growth, symptoms, and quality of life.

    PubMed

    Breivik, Cathrine Nansdal; Nilsen, Roy Miodini; Myrseth, Erling; Pedersen, Paal Henning; Varughese, Jobin K; Chaudhry, Aqeel Asghar; Lund-Johansen, Morten

    2013-07-01

    There are few reports about the course of vestibular schwannoma (VS) patients following gamma knife radiosurgery (GKRS) compared with the course following conservative management (CM). In this study, we present prospectively collected data of 237 patients with unilateral VS extending outside the internal acoustic canal who received either GKRS (113) or CM (124). The aim was to measure the effect of GKRS compared with the natural course on tumor growth rate and hearing loss. Secondary end points were postinclusion additional treatment, quality of life (QoL), and symptom development. The patients underwent magnetic resonance imaging scans, clinical examination, and QoL assessment by SF-36 questionnaire. Statistics were performed by using Spearman correlation coefficient, Kaplan-Meier plot, Poisson regression model, mixed linear regression models, and mixed logistic regression models. Mean follow-up time was 55.0 months (26.1 standard deviation, range 10-132). Thirteen patients were lost to follow-up. Serviceable hearing was lost in 54 of 71 (76%) (CM) and 34 of 53 (64%) (GKRS) patients during the study period (not significant, log-rank test). There was a significant reduction in tumor volume over time in the GKRS group. The need for treatment following initial GKRS or CM differed at highly significant levels (log-rank test, P < .001). Symptom and QoL development did not differ significantly between the groups. In VS patients, GKRS reduces the tumor growth rate and thereby the incidence rate of new treatment about tenfold. Hearing is lost at similar rates in both groups. Symptoms and QoL seem not to be significantly affected by GKRS.

  5. Absorbed dose rates in tissue from prompt gamma emissions from near-thermal neutron absorption

    DOE PAGES

    Schwahn, Scott O.

    2015-10-01

    Prompt gamma emission data from the International Atomic Energy Agency s Prompt Gamma-ray Neutron Activation Analysis database are analyzed to determine the absorbed dose rates in tissue to be expected when natural elements are exposed in a near-thermal neutron environment.

  6. Prediction of terrestrial gamma dose rate based on geological formations and soil types in the Johor State, Malaysia.

    PubMed

    Saleh, Muneer Aziz; Ramli, Ahmad Termizi; bin Hamzah, Khaidzir; Alajerami, Yasser; Moharib, Mohammed; Saeed, Ismael

    2015-10-01

    This study aims to predict and estimate unmeasured terrestrial gamma dose rate (TGDR) using statistical analysis methods to derive a model from the actual measurement based on geological formation and soil type. The measurements of TGDR were conducted in the state of Johor with a total of 3873 measured points which covered all geological formations, soil types and districts. The measurements were taken 1 m above the soil surface using NaI [Ti] detector. The measured gamma dose rates ranged from 9 nGy h(-1) to 1237 nGy h(-1) with a mean value of 151 nGy h(-1). The data have been normalized to fit a normal distribution. Tests of significance were conducted among all geological formations and soil types, using the unbalanced one way ANOVA. The results indicated strong significant differences due to the different geological formations and soil types present in Johor State. Pearson Correlation was used to measure the relations between gamma dose rate based on geological formation and soil type (D(G,S)) with the gamma dose rate based on geological formation (D(G)) or soil type (D(s)). A very good correlation was found between D(G,S) and D(G) or D(G,S) and D(s). A total of 118 pairs of geological formations and soil types were used to derive the statistical contribution of geological formations and soil types to gamma dose rates. The contribution of the gamma dose rate from geological formation and soil type were found to be 0.594 and 0.399, respectively. The null hypotheses were accepted for 83% of examined data, therefore, the model could be used to predict gamma dose rates based on geological formation and soil type information. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. [Meta-analysis of needle-knife treatment on cervical spondylosis].

    PubMed

    Kan, Li-Li; Wang, Hai-Dong; Liu, An-Guo

    2013-11-01

    To assess the efficacy of cervical spondylosis by needle-knife treatment according to the correlated literature of RCT,to compare advantages of needle-knife treatment. Randomized Controlled Trials about needle-knife treatment of cervical spondylosis were indexed from Chinese HowNet (CNKI) and Wanfang (WF) from 2000 to 2012, then were analyzed the efficacy by Review Manager 5.1 software. A total of 13 RCT literatures and 1 419 patients were included. The methods of included studies were poor in quality evaluation because of large sample and multi-center RCT studies was lacked, randomization method was not accurate enough, diagnostic criteria and efficacy evaluation were various, only four studies described long-term efficacy, most of the literature didn't describe the adverse event and fall off,all studies did not use the blind method. The Meta analysis outcome showed overall efficiency of needle-knife therapy was better than acupuncture and traction. Needle-knife therapy compared with Acupuncture, the total RR = 0.19, 95% confidence interval was (0.15, 0.24), P < 0.000.01. Compared with traction therapy the total RR = 1.30, 95% confidence intervalwas (1.18,1.42), P < 0.00001. Compared with acupuncture therapy,the overall effectiveness of needle-knife therapy is higher;compared with traction therapy, although,needle-knife therapy has a high overall effectiveness, but because of the loss of total sample size, the outcome RCT researches to confirm.

  8. Measurements of environmental terrestrial gamma radiation dose rate in three mountainous locations in the western region of Saudi Arabia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Al-Ghorabie, Fayez H.H.

    2005-06-01

    This paper describes measurements of external gamma radiation dose rate from terrestrial gamma-rays 1 m above the ground in three different mountainous locations in the western region of the Kingdom of Saudi Arabia. These locations are At-Taif city, Al-Hada village, and Ash-Shafa village. CaSO{sub 4}:Dy (TLD-900) thermoluminescent dosimeters were used for the detection of terrestrial gamma radiation at 40 different places in the three locations. The values of terrestrial gamma radiation dose rate measured ranged between 14 and 279 nGy h{sup -1} for the time interval from June 2001 to June 2002. The measured dose rate varied with the seasonmore » of the year. The average gamma radiation dose rates were 468, 541, and 781 {mu}Gy y{sup -1} for At-Taif city, Al-Hada village, and Ash-Shafa village, respectively. The corresponding average absorbed doses to the population of the three locations were 328, 379, and 547 {mu}Sv y{sup -1}, respectively. The quality factor of 0.7 Sv Gy{sup -1} was applied in the calculations of the absorbed dose to humans.« less

  9. Tissue-equivalent TL sheet dosimetry system for X- and gamma-ray dose mapping.

    PubMed

    Nariyama, N; Konnai, A; Ohnishi, S; Odano, N; Yamaji, A; Ozasa, N; Ishikawa, Y

    2006-01-01

    To measure dose distribution for X- and gamma rays simply and accurately, a tissue-equivalent thermoluminescent (TL) sheet-type dosemeter and reader system were developed. The TL sheet is composed of LiF:Mg,Cu,P and ETFE polymer, and the thickness is 0.2 mm. For the TL reading, a square heating plate, 20 cm on each side, was developed, and the temperature distribution was measured with an infrared thermal imaging camera. As a result, linearity within 2% and the homogeneity within 3% were confirmed. The TL signal emitted is detected using a CCD camera and displayed as a spatial dose distribution. Irradiation using synchrotron radiation between 10 and 100 keV and (60)Co gamma rays showed that the TL sheet dosimetry system was promising for radiation dose mapping for various purposes.

  10. Laparoscopic pyloromyotomy: is a knife really necessary?

    PubMed

    Jain, Vishesh; Choudhury, Subhasis Roy; Chadha, Rajiv; Puri, Archana; Naga, Abhimanyu Singh

    2012-02-01

    Laparoscopic pyloromyotomy (LP) is currently accepted as a suitable treatment modality for infantile hypertrophic pyloric stenosis (IHPS). In this report, we describe some technical modifications of LP using a 3- or 5-mm hook with electrocautery as a substitute for a knife for incising the pylorus. The outcomes of LP using a standard retractable pyloromyotomy knife are compared with those of LP using a hook electrocautery. The patients with ultrasound proven IHPS who had undergone LP in a single institution from December 2008 to April 2010 were retrospectively analyzed. Incision on the pylorus was made with a 3-mm pyloromyotomy knife in the initial 12 cases. However, in the latter part of the study, a 3- or 5-mm hook with electrocautery was used for the incision. A Maryland dissector was used for completing the pyloromyotomy. The results were compared in terms of duration of surgery, complications, time taken to establish the first full feed, requirement of analgesics, postoperative emesis, and postoperative stay in the hospital. Independent sample t test and the Chi-square test were used for statistical analysis. Of the 27 patients analyzed, 12 underwent LP using a pyloromyotomy knife and the remaining 15 patients were operated on using a hook with electrocautery instead of the knife. The operating time, time taken to establish the first full feed, and duration of hospital stay were comparable among the two groups with no statistically significant difference. No complications were recorded in either group. Use of hook electrocautery for incising the pylorus provides a bloodless field without affecting the postoperative recovery and outcome. It also obviates any need of specialized instruments like a pyloromyotomy knife or other sharp instruments for pyloric incision.

  11. Effect of low dose and moderate dose gamma irradiation on the mechanical properties of bone and soft tissue allografts.

    PubMed

    Balsly, Colleen R; Cotter, Andrew T; Williams, Lisa A; Gaskins, Barton D; Moore, Mark A; Wolfinbarger, Lloyd

    2008-12-01

    The increased use of allograft tissue for musculoskeletal repair has brought more focus to the safety of allogenic tissue and the efficacy of various sterilization techniques. Gamma irradiation is an effective method for providing terminal sterilization to biological tissue, but it is also reported to have deleterious effects on tissue mechanics in a dose-dependent manner. At irradiation ranges up to 25 kGy, a clear relationship between mechanical strength and dose has yet to be established. The aim of this study was to investigate the mechanical properties of bone and soft tissue allografts, irradiated on dry ice at a low absorbed dose (18.3-21.8 kGy) and a moderate absorbed dose (24.0-28.5 kGy), using conventional compressive and tensile testing, respectively. Bone grafts consisted of Cloward dowels and iliac crest wedges, while soft tissue grafts consisted of patellar tendons, anterior tibialis tendons, semitendinosus tendons, and fascia lata. There were no statistical differences in mechanical strength or modulus of elasticity for any graft irradiated at a low absorbed dose, compared to control groups. Also, bone allografts and two soft tissue allografts (anterior tibialis and semitendinosus tendon) that were irradiated at a moderate dose demonstrated similar strength and modulus of elasticity values to control groups. The results of this study support the use of low dose and moderate dose gamma irradiation of bone grafts. For soft tissue grafts, the results support the use of low dose irradiation.

  12. The SKED: speckle knife edge detector

    NASA Astrophysics Data System (ADS)

    Sharpies, S. D.; Light, R. A.; Achamfuo-Yeboah, S. O.; Clark, M.; Somekh, M. G.

    2014-06-01

    The knife edge detector—also known as optical beam deflection—is a simple and robust method of detecting ultrasonic waves using a laser. It is particularly suitable for detection of high frequency surface acoustic waves as the response is proportional to variation of the local tilt of the surface. In the case of a specular reflection of the incident laser beam from a smooth surface, any lateral movement of the reflected beam caused by the ultrasonic waves is easily detected by a pair of photodiodes. The major disadvantage of the knife edge detector is that it does not cope well with optically rough surfaces, those that give a speckled reflection. The optical speckles from a rough surface adversely affect the efficiency of the knife edge detector, because 'dark' speckles move synchronously with 'bright' speckles, and their contributions to the ultrasonic signal cancel each other out. We have developed a new self-adapting sensor which can cope with the optical speckles reflected from a rough surface. It is inelegantly called the SKED—speckle knife edge detector—and like its smooth surface namesake it is simple, cheap, compact, and robust. We describe the theory of its operation, and present preliminary experimental results validating the overall concept and the operation of the prototype device.

  13. A revision of the gamma-evaluation concept for the comparison of dose distributions.

    PubMed

    Bakai, Annemarie; Alber, Markus; Nüsslin, Fridtjof

    2003-11-07

    A method for the quantitative four-dimensional (4D) evaluation of discrete dose data based on gradient-dependent local acceptance thresholds is presented. The method takes into account the local dose gradients of a reference distribution for critical appraisal of misalignment and collimation errors. These contribute to the maximum tolerable dose error at each evaluation point to which the local dose differences between comparison and reference data are compared. As shown, the presented concept is analogous to the gamma-concept of Low et al (1998a Med. Phys. 25 656-61) if extended to (3+1) dimensions. The pointwise dose comparisons of the reformulated concept are easier to perform and speed up the evaluation process considerably, especially for fine-grid evaluations of 3D dose distributions. The occurrences of false negative indications due to the discrete nature of the data are reduced with the method. The presented method was applied to film-measured, clinical data and compared with gamma-evaluations. 4D and 3D evaluations were performed. Comparisons prove that 4D evaluations have to be given priority, especially if complex treatment situations are verified, e.g., non-coplanar beam configurations.

  14. Using the phacoemulsification crescent knife in dacryocystorhinostomy.

    PubMed

    Fong, K S; Koh, A H; Choo, C T

    1998-04-01

    Dacryocystorhinostomy is an effective treatment for nasolacrimal duct obstruction. Most techniques employ a conventional blade or knife in making the incision of the nasal mucosa and lacrimal sac. The authors describe the use of a phacoemulsification crescent knife for this purpose. This technique can be effective and at the same time safer and easier to perform.

  15. SU-F-T-293: Experimental Comparisons of Ionization Chambers with Different Volumes for CyberKnife Delivery Quality Assurance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nakayama, M; Kobe University Graduate School of Medicine, Kobe, Hyogo; Munetomo, Y

    2016-06-15

    Purpose: To evaluate the practicality use of ionization chambers with different volumes for delivery quality assurance of CyberKnife plans, Methods: Dosimetric measurements with a spherical solid water phantom and three ionization chambers with volumes of 0.13, 0.04, and 0.01 cm3 (IBA CC13, CC04, and CC01, respectively) were performed for various CyberKnife clinical treatment plans including both isocentric and nonisocentric delivery. For each chamber, the ion recombination correction factors Ks were calculated using the Jaffe plot method and twovoltage method at a 10-cm depth for a 60-mm collimator field in a water phantom. The polarity correction factors Kpol were determined formore » 5–60-mm collimator fields in same experimental setup. The measured doses were compared to the doses for the detectors calculated using a treatment planning system. Results: The differences in the Ks between the Jaffe plot method and two-voltage method were −0.12, −0.02, and 0.89% for CC13, CC04, and CC01, respectively. The changes in Kpol for the different field sizes were 0.2, 0.3, and 0.8% for CC13, CC04, and CC01, respectively. The measured doses for CC04 and CC01 were within 3% of the calculated doses for the clinical treatment plans with isocentric delivery with collimator fields greater than 12.5 mm. Those for CC13 had differences of over 3% for the plans with isocentric delivery with collimator fields less than 15 mm. The differences for the isocentric plans were similar to those for the single beam plans. The measured doses for each chamber were within 3% of the calculated doses for the non-isocentric plans except for that with a PTV volume less than 1.0 cm{sup 3}. Conclusion: Although there are some limitations, the ionization chamber with a smaller volume is a better detector for verification of the CyberKnife plans owing to the high spatial resolution.« less

  16. On neutron-gamma mixed field dosimetry with LiF:Mg,Ti at radiation protection dose levels.

    PubMed

    Weinstein, M; German, U; Alfassi, Z B

    2006-01-01

    The possibility of using the specific responses of the high temperature Peaks 6 and 7 and Peaks 4 and 5 to different LET radiations was mentioned in the past mainly for very high doses. The applicability of the two regions method for thermal neutrons--gamma ray mixed field dosimetry was investigated by analysing the response of LiF:Mg,Ti dosemeters irradiated to different ratios of thermal neutrons and gamma rays at radiation protection dose levels encountered in routine work conditions, up to approximately 50 mSv. The Region of Interest method was used to define the areas of the Peaks 4 + 5 and 6 + 7. We found that a simple algorithm can be used to determine with good accuracy the separate contributions of neutron and gamma doses.

  17. Cross-Grain Knife Planing Improves Surface Quality and Utilization of Aspen

    Treesearch

    Harold A. Stewart

    1971-01-01

    Aspen at 6 percent moisture content was planed parallel to the grain and across the grain on a cabinet planer with a 25? rake angle, 1/16- and 1/32-inch depth of cut, and 20 knife marks per inch. Aspen was also cross-grain knife planed with a 45? rake angle, 1/32-, 1/16-, and 1/8-inch depths of cut, and 20, 10, 5, and 2.5 knife marks per inch. Cross-grain knife...

  18. THE EFFECTS OF LOW DOSES OF GAMMA RADIATION ON PLANT YIELDS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bowen, H.J.M.; Cawse, P.A.; Smith, S.R.

    1962-09-01

    the effects of low doses of gamma radiation from Co/sup 60/ were tested on dormant seeds of flax, radish, and cabbage, and on young plants of flax, cabbage, lettuce, ciover, duckweed, and pine. Fresh or dry weights were taken as a measure of yieid at harvest. Only in the case of pine seedlings was significant stimulation noticed: this occurred in the dose range 2 to 6 rad after 9 months growth. (auth)

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Franzin, Alberto; Snider, Silvia; Picozzi, Piero

    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 (140more » 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.« less

  20. Laparoscopic pyloromyotomy: comparing the arthrotomy knife to the Bovie blade.

    PubMed

    Thomas, Priscilla G; Sharp, Nicole E; St Peter, Shawn D

    2014-07-01

    Laparoscopic pyloromyotomy was performed at our institution using an arthrotomy knife until it became unavailable in 2010. Thus, we adapted the use of the blunt Bovie tip, which can be used with or without electrocautery to perform the myotomy. This study compared the outcomes between using the arthrotomy knife versus the Bovie blade in laparoscopic pyloromyotomies. Retrospective review was performed on all laparoscopic pyloromyotomy patients from October 2007 to September 2012. Arthrotomy knife pyloromyotomy patients were compared with those performed with the Bovie blade. Patient demographics, diagnostic measurements, electrolyte levels, length of stay, operative time, and complications were compared. A total of 381 patients were included, with 191 in the arthrotomy group and 190 in the Bovie blade group. No significant differences existed between groups in age, weight, gender, pyloric dimensions, electrolyte levels, or length of stay. Mean operative times were 15.8±5.6 min with knife and 16.4±5.3 min for Bovie blade (P=0.24). In the arthrotomy knife group, there was one incomplete pyloromyotomy and one omental herniation. There was one wound infection in each group. Readmission rate was greater in the arthrotomy knife group (5.7%) versus the Bovie blade group (3.1%). The Bovie blade appears to offer no objective disadvantages compared with the arthrotomy knife when performing laparoscopic pyloromyotomy. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Automatic optimisation of gamma dose rate sensor networks: The DETECT Optimisation Tool

    NASA Astrophysics Data System (ADS)

    Helle, K. B.; Müller, T. O.; Astrup, P.; Dyve, J. E.

    2014-05-01

    Fast delivery of comprehensive information on the radiological situation is essential for decision-making in nuclear emergencies. Most national radiological agencies in Europe employ gamma dose rate sensor networks to monitor radioactive pollution of the atmosphere. Sensor locations were often chosen using regular grids or according to administrative constraints. Nowadays, however, the choice can be based on more realistic risk assessment, as it is possible to simulate potential radioactive plumes. To support sensor planning, we developed the DETECT Optimisation Tool (DOT) within the scope of the EU FP 7 project DETECT. It evaluates the gamma dose rates that a proposed set of sensors might measure in an emergency and uses this information to optimise the sensor locations. The gamma dose rates are taken from a comprehensive library of simulations of atmospheric radioactive plumes from 64 source locations. These simulations cover the whole European Union, so the DOT allows evaluation and optimisation of sensor networks for all EU countries, as well as evaluation of fencing sensors around possible sources. Users can choose from seven cost functions to evaluate the capability of a given monitoring network for early detection of radioactive plumes or for the creation of dose maps. The DOT is implemented as a stand-alone easy-to-use JAVA-based application with a graphical user interface and an R backend. Users can run evaluations and optimisations, and display, store and download the results. The DOT runs on a server and can be accessed via common web browsers; it can also be installed locally.

  2. Foods for a Mission to Mars: Investigations of Low-Dose Gamma Radiation Effects

    NASA Technical Reports Server (NTRS)

    Gandolph, J.; Shand, A.; Stoklosa, A.; Ma, A.; Weiss, I.; Alexander, D.; Perchonok, M.; Mauer, L. J.

    2007-01-01

    Food must be safe, nutritious, and acceptable throughout a long duration mission to maintain the health, well-being, and productivity of the astronauts. In addition to a developing a stable pre-packaged food supply, research is required to better understand the ability to convert edible biomass into safe, nutritious, and acceptable food products in a closed system with many restrictions (mass, volume, power, crew time, etc.). An understanding of how storage conditions encountered in a long-term space mission, such as elevated radiation, will impact food quality is also needed. The focus of this project was to contribute to the development of the highest quality food system possible for the duration of a mission, considering shelf-stable extended shelf-life foods, bulk ingredients, and crops to be grown in space. The impacts of space-relevant radiation doses on food, bulk ingredient, and select candidate crop quality and antioxidant capacity were determined. Interestingly, increasing gamma-radiation doses (0 to 1000 Gy) did not always increase dose-related effects in foods. Intermediate radiation doses (10 to 800Gy) often had significantly larger impact on the stability of bulk ingredient oils than higher (1000Gy) radiation doses. Overall, most food, ingredient, and crop systems investigated showed no significant differences between control samples and those treated with 3 Gy of gamma radiation (the upper limit estimated for a mission to Mars). However, this does not mean that all foods will be stable for 3-5 years, nor does it mean that foods are stable to space radiation comprising more than gamma rays.

  3. SU-E-T-647: Quality Assurance of VMAT by Gamma Analysis Dependence On Low-Dose Threshold

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Song, J; Kim, M; Lee, S

    2015-06-15

    Purpose: The AAPM TG-119 instructed institutions to use low-dose threshold (LDT) of 10% or a ROI determined by the jaw when they collected gamma analysis QA data of planar dose distribution. Also, based on a survey by Nelms and Simon, more than 70% of institutions use a LDT between 0% and 10% for gamma analysis. However, there are no clinical data to quantitatively demonstrate the impact of the LDT on the gamma index. Therefore, we performed a gamma analysis with LDTs of 0% to 15% according to both global and local normalization and different acceptance criteria: 3%/3 mm, 2%/2 mm,more » and 1%/1 mm. Methods: A total of 30 treatment plans—10 head and neck, 10 brain, and 10 prostate cancer cases—were randomly selected from the Varian Eclipse TPS, retrospectively. For the gamma analysis, a predicted portal image was acquired through a portal dose calculation algorithm in the Eclipse TPS, and a measured portal image was obtained using a Varian Clinac iX and an EPID. Then, the gamma analysis was performed using the Portal Dosimetry software. Results: For the global normalization, the gamma passing rate (%GP) decreased as the LDT increased, and all cases of low-dose thresholds exhibited a %GP above 95% for both the 3%/3 mm and 2%/2 mm criteria. However, for local normalization, the %GP increased as LDT increased. The gamma passing rate with LDT of 10% increased by 6.86%, 9.22% and 6.14% compared with the 0% in the case of the head and neck, brain and prostate for 3%/3 mm criteria, respectively. Conclusion: Applying the LDT in the global normalization does not have critical impact to judge patient-specific QA results. However, LDT for the local normalization should be carefully selected because applying the LDT could affect the average of the %GP to increase rapidly.« less

  4. Lithotomy versus jack-knife position on haemodynamic parameters assessed by impedance cardiography during anorectal surgery under low dose spinal anaesthesia: a randomized controlled trial.

    PubMed

    Borodiciene, Jurgita; Gudaityte, Jurate; Macas, Andrius

    2015-05-06

    Although the prone position providing better exposure for anorectal surgery is required it can cause a reduction of cardiac output and cardiac index. The goal was to compare haemodynamic changes assessed by impedance cardiography during anorectal surgery under low-dose spinal anaesthesia in lithotomy and jack-knife position. The prospective randomized controlled study included 104, ASA I-II adult patients admitted for elective minor anorectal surgery, assigned to be performed in lithotomy (groupL, n = 52) or jack-knife position (groupJ, n = 52). After arrival to operating room the standard monitoring, impedance cardiography device was connected to the patient, and the following variables were recorded: cardiac output, cardiac index, systemic vascular resistance, stroke index at times of arrival to operating room, placement for, start and end of surgery and placement to bed. Spinal block was made in the sitting position with 4 mg of 0.5% hyperbaric bupivacaine and 10 μg of Fentanyl injected over 2 min. Comparison was based on haemodynamic changes between and inside groups over time. Student's t, chi square tests were used for statistical analysis with p < 0.05 regarded as statistically significant. The reduction of cardiac output was statistically significant after placement of the patient into the prone position: from baseline 7.4+/-1.6 to 4.9+/-1.2 after placement for and 4.7+/-1.2 at the start and end of surgery (mean +/-SD l/min). The difference of cardiac output between groups was 2.0 l/min after positioning for and the start of surgery and 1.5 l/min at the end of surgery (p < 0.05). Mean cardiac index reduced from baseline 3.9+/-0.8 to 2.6+/-0.7 and 2.4+/-0.6 (mean+/-SD l/min/m(2)) in groupJ and between groups: by 1.0 l/min/m(2) after placement for, 1.1 at the start and 0.8 at the end of surgery (p < 0.05). Systemic vascular resistance increased from baseline 1080+/-338 to 1483+/-479 after placement for, 1523+/-481 at the start and 1525

  5. Morphological changes induced by different doses of gamma irradiation in garlic sprouts

    NASA Astrophysics Data System (ADS)

    Pellegrini, C. N.; Croci, C. A.; Orioli, G. A.

    2000-03-01

    The objective of this work was to evaluate the effects of different doses of gamma rays applied in dormancy and post-dormancy on garlic bulbs in relation with some morphophysiological parameters. High (commercial) doses cause the complete inhibition of sprouting and mitosis (due to nuclear aberrations). Relatively low doses show no effects on bulbs but doses of 10 Gy applied in post-dormancy reduce sprouting and stop mitosis. This inhibition becomes noticeable from 150 days post-harvest onwards. Exogenous growth regulators can reverse these effects. Results may reinforce the good practice of radioinhibition processes in garlic.

  6. Using RADFET for the real-time measurement of gamma radiation dose rate

    NASA Astrophysics Data System (ADS)

    Andjelković, Marko S.; Ristić, Goran S.; Jakšić, Aleksandar B.

    2015-02-01

    RADFETs (RADiation sensitive Field Effect Transistors) are integrating ionizing radiation dosimeters operating on the principle of conversion of radiation-induced threshold voltage shift into absorbed dose. However, one of the major drawbacks of RADFETs is the inability to provide the information on the dose rate in real-time using the conventional absorbed dose measurement technique. The real-time monitoring of dose rate and absorbed dose can be achieved with the current mode dosimeters such as PN and PIN diodes/photodiodes, but these dosimeters have some limitations as absorbed dose meters and hence they are often not a suitable replacement for RADFETs. In that sense, this paper investigates the possibility of using the RADFET as a real-time dose rate meter so that it could be applied for simultaneous online measurement of the dose rate and absorbed dose. A RADFET sample, manufactured by Tyndall National Institute, Cork, Ireland, was tested as a dose rate meter under gamma irradiation from a Co-60 source. The RADFET was configured as a PN junction, such that the drain, gate and source terminals were grounded, while the radiation-induced current was measured at the bulk terminal, whereby the bulk was successively biased with 0 , 10 , 20  and 30 V. In zero-bias mode the radiation-induced current was unstable, but in the biased mode the current response was stable for the investigated dose rates from 0.65  to 32.1 Gy h-1 and up to the total absorbed dose of 25 Gy. The current increased with the dose rate in accordance with the power law, whereas the sensitivity of the current read-out was linear with respect to the applied bias voltage. Comparison with previously analyzed PIN photodiodes has shown that the investigated RADFET is competitive with PIN photodiodes as a gamma radiation dose rate meter and therefore has the potential to be employed for the real-time monitoring of the dose rate and absorbed dose.

  7. Predictors of quality of life and survival following Gamma Knife surgery for lung cancer brain metastases: a prospective study.

    PubMed

    Bragstad, Sidsel; Flatebø, Marianne; Natvig, Gerd Karin; Eide, Geir Egil; Skeie, Geir Olve; Behbahani, Maziar; Pedersen, Paal-Henning; Enger, Per Øyvind; Skeie, Bente Sandvei

    2017-08-18

    OBJECTIVE Lung cancer (LC) patients who develop brain metastases (BMs) have a poor prognosis. Estimations of survival and risk of treatment-related deterioration in quality of life (QOL) are important when deciding on treatment. Although we know of several prognostic factors for LC patients with BMs, the role of QOL has not been established. Authors of this study set out to evaluate changes in QOL following Gamma Knife surgery (GKS) for BMs in LC patients and QOL as a prognostic factor for survival. METHODS Forty-four of 48 consecutive LC patients with BMs underwent GKS in the period from May 2010 to September 2011, and their QOL was prospectively assessed before and 1, 3, 6, 9, and 12 months after GKS by using the Functional Assessment of Cancer Therapy-Brain (FACT-BR) questionnaire. A mixed linear regression model was used to identify potential predictive factors for QOL and to assess the effect of GKS and the disease course on QOL at follow-up. RESULTS Mean QOL as measured by the brain cancer subscale (BRCS) of the FACT-BR remained stable from baseline (score 53.0) up to 12 months post-GKS (57.1; p = 0.624). The BRCS score improved for 32 patients (72.3%) with a total BM volume ≤ 5 cm 3 . Mean improvement in these patients was 0.45 points each month of follow-up, compared to a decline of 0.50 points each month despite GKS treatment in patients with BM volumes > 5 cm 3 (p = 0.04). Asymptomatic BMs (p = 0.01), a lower recursive partitioning analysis (RPA) classification (p = 0.04), and a higher Karnofsky Performance Scale (KPS) score (p < 0.01) at baseline were predictors for a high, stable QOL after GKS. After multivariate analysis, a high KPS score (p < 0.01) remained the only positive predictor of a high, stable QOL post-GKS. Median survival post-GKS was 5.6 months (95% CI 1.0-10.3). A higher BRCS score (p = 0.01), higher KPS score (p = 0.01), female sex (p = 0.01), and the absence of liver (p = 0.02), adrenal (p = 0.02), and bone metastases (p = 0

  8. Total target volume is a better predictor of whole brain dose from gamma stereotactic radiosurgery than the number, shape, or location of the lesions

    PubMed Central

    Narayanasamy, Ganesh; Smith, Adam; Van Meter, Emily; McGarry, Ronald; Molloy, Janelle A.

    2013-01-01

    Purpose: To assess the hypothesis that the volume of whole brain that receives a certain dose level is primarily dependent on the treated volume rather than on the number, shape, or location of the lesions. This would help a physician validate the suitability of GammaKnife® based stereotactic radiosurgery (GKSR) prior to treatment. Methods: Simulation studies were performed to establish the hypothesis for both oblong and spherical shaped lesions of various numbers and sizes. Forty patients who underwent GKSR [mean age of 54 years (range 7–80), mean number of lesions of 2.5 (range 1–6), and mean lesion volume of 4.4 cm3 (range 0.02–22.2 cm3)] were also studied retrospectively. Following recommendations of QUANTEC, the volume of brain irradiated by the 12 Gy (VB12) isodose line was measured and a power-law based relation is proposed here for estimating VB12 from the known tumor volume and the prescription dose. Results: In the simulation study on oblong, spherical, and multiple lesions, the volume of brain irradiated by 50%, 10%, and 1% of maximum dose was found to have linear, linear, and exponentially increasing dependence on the volume of the treated region, respectively. In the retrospective study on 40 GKSR patients, a similar relationship was found to predict the brain dose with a Spearman correlation coefficient >0.9. In both the studies, the volume of brain irradiated by a certain dose level does not have a statistically significant relationship (p ≥ 0.05) with the number, shape, or position of the lesions. The measured VB12 agrees with calculation to within 1.7%. Conclusions: The results from the simulation and the retrospective clinical studies indicate that the volume of whole brain that receives a certain percentage of the maximum dose is primarily dependent on the treated volume and less on the number, shape, and location of the lesions. PMID:24007147

  9. NEEDLE KNIFE SPHINCTEROTOMY - THE CHRIS HANI BARAGWANATH ACADEMIC HOSPITAL EXPERIENCE.

    PubMed

    Thomson, J T; Smith, M D; Omoshoro-Jones, J A O; Devar, J D; Khan, Z K; Jugmohan, B J

    2017-06-01

    Deep biliary cannulation is essential in performing a therapeutic ERCP. Cannulation can be enhanced through the utilization of a pre-cut by means of a needle knife sphincterotomy. Retrospective analysis of the Chris Hani Baragwanath Academic Hospital's ERCP database was performed. All ERCPs performed with the aid of a needle knife were identified and analysed for successful and unsuccessful deep biliary cannulation. 2830 ERCPs were performed during the study period. 369 (13%) required needle knife sphincterotomies and successful deep biliary cannulation was achieved in 229 (62%) of these patients. Repeat ERCPs were performed on 125 (34%) patients. 61 (49%) of the repeat ERCPs were performed because of previously failed cannulation. 34 (56%) of these repeat ERCPs resulted in successful deep biliary cannulation at re-attempt. 99% of successful cannulations at repeat ERCP had had a needle knife sphincterotomy at the first ERCP. Needle knife sphincterotomy improves deep biliary cannulation at initial ERCP and subsequent ERCPs with low incidences of complications.

  10. Efficacy of a Novel Narrow Knife with Water Jet Function for Colorectal Endoscopic Submucosal Dissection.

    PubMed

    Yoshida, Naohisa; Toyonaga, Takashi; Murakami, Takaaki; Hirose, Ryohei; Ogiso, Kiyoshi; Inada, Yutaka; Rani, Rafiz Abdul; Naito, Yuji; Kishimoto, Mitsuo; Ohara, Yoshiko; Azuma, Takeshi; Itoh, Yoshito

    2017-01-01

    With respect to the knife's design in colorectal endoscopic submucosal dissection (ESD), diameter, water jet function, and electric power are important because these relate to efficient dissection. In this study, we analyzed a novel, narrow ball tip-typed ESD knife with water jet function (Flush knife BT-S, diameter: 2.2 mm, length: 2000 mm, Fujifilm Co., Tokyo, Japan) compared to a regular diameter knife (Flush knife BT, diameter: 2.6 mm, length: 1800 mm). In laboratory and clinical research, electric power, knife insertion time, vacuum/suction amount with knife in the endoscopic channel, and water jet function were analyzed. We used a knife 2.0 mm long for BT-S and BT knives. The BT-S showed faster mean knife insertion time (sec) and better vacuum amount (ml/min) compared to the BT (insertion time: 16.7 versus 21.6, p < 0.001, vacuum amount: 38.0 versus 14.0, p < 0.01). Additionally, the water jet function of the BT-S was not inferior. In 39 colorectal ESD cases in two institutions, there were mean 4.7 times (range: 1-28) of knife insertion. Suction under knife happened 59% (23/39) and suction of fluid could be done in 100%. Our study showed that the narrow knife allows significantly faster knife insertion, better vacuum function, and effective clinical results.

  11. Amorphous and crystalline optical materials used as instruments for high gamma radiation doses estimations

    NASA Astrophysics Data System (ADS)

    Ioan, M.-R.

    2016-06-01

    Nuclear radiation induce some changes to the structure of exposed materials. The main effect of ionizing radiation when interacting with optical materials is the occurrence of color centers, which are quantitatively proportional to the up-taken doses. In this paper, a relation between browning effect magnitude and dose values was found. Using this relation, the estimation of a gamma radiation dose can be done. By using two types of laser wavelengths (532 nm and 633 nm), the optical powers transmitted thru glass samples irradiated to different doses between 0 and 59.1 kGy, were measured and the associated optical browning densities were determined. The use of laser light gives the opportunity of using its particularities: monochromaticity, directionality and coherence. Polarized light was also used for enhancing measurements quality. These preliminary results bring the opportunity of using glasses as detectors for the estimation of the dose in a certain point in space and for certain energy, especially in particles accelerators experiments, where the occurred nuclear reactions are involving the presence of high gamma rays fields.

  12. Development of stereotactic radiosurgery using carbon beams (carbon-knife)

    NASA Astrophysics Data System (ADS)

    Keawsamur, Mintra; Matsumura, Akihiko; Souda, Hikaru; Kano, Yosuke; Torikoshi, Masami; Nakano, Takashi; Kanai, Tatsuaki

    2018-02-01

    The aim of this research is to develop a stereotactic-radiosurgery (SRS) technique using carbon beams to treat small intracranial lesions; we call this device the carbon knife. A 2D-scanning method is adapted to broaden a pencil beam to an appropriate size for an irradiation field. A Mitsubishi slow extraction using third order resonance through a rf acceleration system stabilized by a feed-forward scanning beam using steering magnets with a 290 MeV/u initial beam energy was used for this purpose. Ridge filters for spread-out Bragg peaks (SOBPs) with widths of 5 mm, 7.5 mm, and 10 mm were designed to include fluence-attenuation effects. The collimator, which defines field shape, was used to reduce the lateral penumbra. The lateral-penumbra width at the SOBP region was less than 2 mm for the carbon knife. The penumbras behaved almost the same when changing the air gap, but on the other hand, increasing the range-shifter thickness mostly broadened the lateral penumbra. The physical-dose rates were approximate 6 Gy s-1 and 4.5 Gy s-1 for the 10  ×  10 mm2 and 5  ×  5 mm2 collimators, respectively.

  13. Efficacy of a Novel Narrow Knife with Water Jet Function for Colorectal Endoscopic Submucosal Dissection

    PubMed Central

    Inada, Yutaka; Rani, Rafiz Abdul; Naito, Yuji; Azuma, Takeshi; Itoh, Yoshito

    2017-01-01

    Backgrounds With respect to the knife's design in colorectal endoscopic submucosal dissection (ESD), diameter, water jet function, and electric power are important because these relate to efficient dissection. In this study, we analyzed a novel, narrow ball tip-typed ESD knife with water jet function (Flush knife BT-S, diameter: 2.2 mm, length: 2000 mm, Fujifilm Co., Tokyo, Japan) compared to a regular diameter knife (Flush knife BT, diameter: 2.6 mm, length: 1800 mm). Methods In laboratory and clinical research, electric power, knife insertion time, vacuum/suction amount with knife in the endoscopic channel, and water jet function were analyzed. We used a knife 2.0 mm long for BT-S and BT knives. Results The BT-S showed faster mean knife insertion time (sec) and better vacuum amount (ml/min) compared to the BT (insertion time: 16.7 versus 21.6, p < 0.001, vacuum amount: 38.0 versus 14.0, p < 0.01). Additionally, the water jet function of the BT-S was not inferior. In 39 colorectal ESD cases in two institutions, there were mean 4.7 times (range: 1–28) of knife insertion. Suction under knife happened 59% (23/39) and suction of fluid could be done in 100%. Conclusions Our study showed that the narrow knife allows significantly faster knife insertion, better vacuum function, and effective clinical results. PMID:29081793

  14. Terrestrial Gamma Radiation Dose Rate of West Sarawak

    NASA Astrophysics Data System (ADS)

    Izham, A.; Ramli, A. T.; Saridan Wan Hassan, W. M.; Idris, H. N.; Basri, N. A.

    2017-10-01

    A study of terrestrial gamma radiation (TGR) dose rate was conducted in west of Sarawak, covering Kuching, Samarahan, Serian, Sri Aman, and Betong divisions to construct a baseline TGR dose rate level data of the areas. The total area covered was 20,259.2 km2, where in-situ measurements of TGR dose rate were taken using NaI(Tl) scintillation detector Ludlum 19 micro R meter NaI(Tl) approximately 1 meter above ground level. Twenty-nine soil samples were taken across the 5 divisions covering 26 pairings of 9 geological formations and 7 soil types. A hyperpure Germanium detector was then used to find the samples' 238U, 232Th, and 40K radionuclides concentrations producing a correction factor Cf = 0.544. A total of239 measured data were corrected with Cf resulting in a mean Dm of 47 ± 1 nGy h-1, with a range between 5 nGy h-1 - 103 nGy h-1. A multiple regression analysis was conducted between geological means and soil types means against the corrected TGR dose rate Dm, generating Dg,s= 0.847Dg+ 0.637Ds- 22.313 prediction model with a normalized Beta equation of Dg,s= 0.605Dg+ 0.395Ds. The model has an 84.6% acceptance of Whitney- Mann test null hypothesis when tested against the corrected TGR dose rates.

  15. Optimal mapping of terrestrial gamma dose rates using geological parent material and aerogeophysical survey data.

    PubMed

    Rawlins, B G; Scheib, C; Tyler, A N; Beamish, D

    2012-12-01

    Regulatory authorities need ways to estimate natural terrestrial gamma radiation dose rates (nGy h⁻¹) across the landscape accurately, to assess its potential deleterious health effects. The primary method for estimating outdoor dose rate is to use an in situ detector supported 1 m above the ground, but such measurements are costly and cannot capture the landscape-scale variation in dose rates which are associated with changes in soil and parent material mineralogy. We investigate the potential for improving estimates of terrestrial gamma dose rates across Northern Ireland (13,542 km²) using measurements from 168 sites and two sources of ancillary data: (i) a map based on a simplified classification of soil parent material, and (ii) dose estimates from a national-scale, airborne radiometric survey. We used the linear mixed modelling framework in which the two ancillary variables were included in separate models as fixed effects, plus a correlation structure which captures the spatially correlated variance component. We used a cross-validation procedure to determine the magnitude of the prediction errors for the different models. We removed a random subset of 10 terrestrial measurements and formed the model from the remainder (n = 158), and then used the model to predict values at the other 10 sites. We repeated this procedure 50 times. The measurements of terrestrial dose vary between 1 and 103 (nGy h⁻¹). The median absolute model prediction errors (nGy h⁻¹) for the three models declined in the following order: no ancillary data (10.8) > simple geological classification (8.3) > airborne radiometric dose (5.4) as a single fixed effect. Estimates of airborne radiometric gamma dose rate can significantly improve the spatial prediction of terrestrial dose rate.

  16. Penetration tests to study the mechanical tribological properties of chisel type knife

    NASA Astrophysics Data System (ADS)

    Vlăduţoiu, L.; Chişiu, G.; Andrei, T.; Predescu, A.; Muraru, C.; Vlăduţ, V.

    2017-02-01

    The goal of this study was to analyze the behaviour of chisel knife type penetration in a certain type of sand. A series of penetration tests were carried out with chisel knife type, the answer to penetration depending mainly on nature, shape, size of knife and operating parameters such as speed, depth and working conditions. Tests were conducted in work conditions with wet sand and dry sand and determined force of resistance to penetration of the chisel knife type to a certain depth.

  17. Pros, cons, and current indications of open craniotomy versus gamma knife in the treatment of arteriovenous malformations and the role of endovascular embolization.

    PubMed

    Surdell, Daniel L; Bhattacharjee, Sumon; Loftus, Christopher M

    2002-06-01

    The successful treatment of an intracranial arteriovenous malformation poses both technical and conceptual problems to the neurosurgeon. Treatment decisions are made in light of current understanding of the natural history of these lesions. It is important to understand the pros, cons and current indication of open craniotomy vs. gamma knife in the treatment of arteriovenous malformations and the role of endovascular embolization. Surgical removal of an arteriovenous malformation is indicated when the operative risk is less than the morbidity and mortality associated with its natural history. The treatment goal of complete angiographic obliteration of arteriovenous malformations is achieved most effectively by microneurosurgery in low-grade lesions. Large lesions frequently require a combination of embolization and microsurgery. Although recent advances in technology and medical management have allowed previously inoperable arteriovenous malformations to be surgically excised, there is still a small group of arteriovenous malformations that cannot be excised safely due to their size and location. Stereotactic radiosurgery is clearly an important adjunct in the multimodality treatment approach for large arteriovenous malformations. Endovascular embolization can potentially increase safety and efficacy in the treatment of arteriovenous malformations when applied to selective cases with well-defined treatment goals.

  18. EFFECT OF MODERATE DOSES OF GAMMA RADIATION ON THE KEEPING QUALITY OF BILBERRIES (VACCINIUM MYRTILLUS)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Horubala, A.; Pijanowski, E.

    1961-01-01

    Three batches of bilberries (European blueberries) in small polythene bags were treated with various doses of gamma radiation and kept afterwards either at ambient or cool storage temperatures for about 10 to 25 days. The dose of about 0.3 Mrad caused the destruction of somewhat more than 99% of the original microflora (bacteria, yeasts and moulds) and thus increased by 250 to 300% the storage life of berries in comparison with untreated fruit. Losses of anthocyanin pigments, vitamin C, and jellifying power were rather small, and the subsequent changes in flavor were practically non existant. The authors recommend the applicationmore » of moderate doses of gamma -rays (about 0.3 Mrad) to exported bilberries prior to their shipment. (auth)« less

  19. Fieldable computer system for determining gamma-ray pulse-height distributions, flux spectra, and dose rates from Little Boy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moss, C.E.; Lucas, M.C.; Tisinger, E.W.

    1984-01-01

    Our system consists of a LeCroy 3500 data acquisition system with a built-in CAMAC crate and eight bismuth-germanate detectors 7.62 cm in diameter and 7.62 cm long. Gamma-ray pulse-height distributions are acquired simultaneously for up to eight positions. The system was very carefully calibrated and characterized from 0.1 to 8.3 MeV using gamma-ray spectra from a variety of radioactive sources. By fitting the pulse-height distributions from the sources with a function containing 17 parameters, we determined theoretical repsonse functions. We use these response functions to unfold the distributions to obtain flux spectra. A flux-to-dose-rate conversion curve based on the workmore » of Dimbylow and Francis is then used to obtain dose rates. Direct use of measured spectra and flux-to-dose-rate curves to obtain dose rates avoids the errors that can arise from spectrum dependence in simple gamma-ray dosimeter instruments. We present some gamma-ray doses for the Little Boy assembly operated at low power. These results can be used to determine the exposures of the Hiroshima survivors and thus aid in the establishment of radation exposure limits for the nuclear industry.« less

  20. Dose rate estimation around a 60Co gamma-ray irradiation source by means of 115mIn photoactivation.

    PubMed

    Murataka, Ayanori; Endo, Satoru; Kojima, Yasuaki; Shizuma, Kiyoshi

    2010-01-01

    Photoactivation of nuclear isomer (115m)In with a halflife of 4.48 h occurs by (60)Co gamma-ray irradiation. This is because the resonance gamma-ray absorption occurs at 1078 keV level for stable (115)In, and that energy gamma-rays are produced by Compton scattering of (60)Co primary gamma-rays. In this work, photoactivation of (115m)In was applied to estimate the dose rate distribution around a (60)Co irradiation source utilizing a standard dose rate taken by alanine dosimeter. The (115m)In photoactivation was measured at 10 to 160 cm from the (60)Co source. The derived dose rate distribution shows a good agreement with both alanine dosimeter data and Monte Carlo simulation. It is found that angular distribution of the dose rate along a circumference at radius 2.8 cm from the central axis shows +/- 10% periodical variation reflecting the radioactive strength of the source rods, but less periodic distribution at radius 10 and 20 cm. The (115m)In photoactivation along the vertical direction in the central irradiation port strongly depends on the height and radius as indicated by Monte Carlo simulation. It is demonstrated that (115m)In photoactivation is a convenient method to estimate the dose rate distribution around a (60)Co source.

  1. Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines

    NASA Technical Reports Server (NTRS)

    Gridley, D. S.; Pecaut, M. J.; Miller, G. M.; Moyers, M. F.; Nelson, G. A.

    2001-01-01

    The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p < 0.05). Basal proliferation of leukocytes in the blood and spleen increased significantly with increasing dose (p < 0.05). Significant dose rate effects were observed only in thrombocyte counts. Plasma levels of transforming growth factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.

  2. Assessment of individual organ doses in a realistic human phantom from neutron and gamma stimulated spectroscopy of the breast and liver

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Belley, Matthew D.; Segars, William Paul; Kapadia, Anuj J., E-mail: anuj.kapadia@duke.edu

    2014-06-15

    Purpose: Understanding the radiation dose to a patient is essential when considering the use of an ionizing diagnostic imaging test for clinical diagnosis and screening. Using Monte Carlo simulations, the authors estimated the three-dimensional organ-dose distribution from neutron and gamma irradiation of the male liver, female liver, and female breasts for neutron- and gamma-stimulated spectroscopic imaging. Methods: Monte Carlo simulations were developed using the Geant4 GATE application and a voxelized XCAT human phantom. A male and a female whole body XCAT phantom was voxelized into 256 × 256 × 600 voxels (3.125 × 3.125 × 3.125 mm{sup 3}). A monoenergeticmore » rectangular beam of 5.0 MeV neutrons or 7.0 MeV photons was made incident on a 2 cm thick slice of the phantom. The beam was rotated at eight different angles around the phantom ranging from 0° to 180°. Absorbed dose was calculated for each individual organ in the body and dose volume histograms were computed to analyze the absolute and relative doses in each organ. Results: The neutron irradiations of the liver showed the highest organ dose absorption in the liver, with appreciably lower doses in other proximal organs. The dose distribution within the irradiated slice exhibited substantial attenuation with increasing depth along the beam path, attenuating to ∼15% of the maximum value at the beam exit side. The gamma irradiation of the liver imparted the highest organ dose to the stomach wall. The dose distribution from the gammas showed a region of dose buildup at the beam entrance, followed by a relatively uniform dose distribution to all of the deep tissue structures, attenuating to ∼75% of the maximum value at the beam exit side. For the breast scans, both the neutron and gamma irradiation registered maximum organ doses in the breasts, with all other organs receiving less than 1% of the breast dose. Effective doses ranged from 0.22 to 0.37 mSv for the neutron scans and 41 to 66 mSv for

  3. Exfoliated graphite with graphene flakes as potential candidates for TL dosimeters at high gamma doses.

    PubMed

    Ortiz-Morales, A; López-González, E; Rueda-Morales, G; Ortega-Cervantez, G; Ortiz-Lopez, J

    2018-06-06

    Graphite powder (GP) subjected to microwave radiation (MWG) results in exfoliation of graphite particles into few-layered graphene flakes (GF) intermixed with partially exfoliated graphite particles (PEG). Characterization of MWG by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Raman spectroscopy reveal few-layer GF with sizes ranging from 0.2 to 5 µm. Raman D, G, and 2D (G') bands characteristic of graphitic structures include evidence of the presence of bilayered graphene. The thermoluminescent (TL) dosimetric properties of MWG are evaluated and can be characterized as a gamma-ray sensitive and dose-resistant material with kinetic parameters (activation energy for the main peak located at 400 and 408 K is 0.69 and 0.72 eV) and threshold dose (~1 kGy and 5 kGy respectively). MWG is a low-Z material (Z eff = 6) with a wide linear range of TL dose-response (0.170-2.5 kGy) tested at doses in the 1-20 kGy range with promising results for applications in gamma-ray dosimetry. Results obtained in gamma irradiated MWG are compared with those obtained in graphite powder samples (GP) without microwave treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Super-resolved terahertz microscopy by knife-edge scan

    NASA Astrophysics Data System (ADS)

    Giliberti, V.; Flammini, M.; Ciano, C.; Pontecorvo, E.; Del Re, E.; Ortolani, M.

    2017-08-01

    We present a compact, all solid-state THz confocal microscope operating at 0.30 THz that achieves super-resolution by using the knife-edge scan approach. In the final reconstructed image, a lateral resolution of 60 μm ≍ λ/17 is demonstrated when the knife-edge is deep in the near-field of the sample surface. When the knife-edge is lifted up to λ/4 from the sample surface, a certain degree of super-resolution is maintained with a resolution of 0.4 mm, i.e. more than a factor 2 if compared to the diffraction-limited scheme. The present results open an interesting path towards super-resolved imaging with in-depth information that would be peculiar to THz microscopy systems.

  5. SU-E-T-281: Reduction of Treatment Times in CyberKnife Prostate SBRT Using a Water Filled Rectal Balloon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Desai, P; Caroprese, B; McKellar, H

    2014-06-01

    Purpose: To illustrate 25% reduction in CyberKnife prostate SBRT treatment times using a water filled rectal balloon. Methods: We perform prostate SBRT using a 3800cGy in 4 fraction regimen prescribed between 51% 59% iso-dose lines to 95% of PTV using a CyberKnife System. The resultant heterogeneous dosimetry is analogous to HDR dosimetry. Our patients are treated in a feet first supine position to decrease treatment couch sag and also to position the prostate anatomy closer to the robot. CT imaging is performed with a Radiadyne Immobiloc rectal balloon filled with 45-50cc water placed firmly inside the patient's rectum. A treatmentmore » plan is developed from this CT study using Multiplan. The patient is treated every other day for 4 days using the rectal balloon for each fraction. Gold fiducials previously implanted inside the prostate are used for tracking by the CyberKnife system. Results: Critical structures comprise the usual GU anatomy of bladder, rectum, urethra, femoral-heads along with emphasis on doses to anterior rectal wall and rectal mucosa. The water filled rectal balloon localizes the rectum, which enables the physician to accurately contour both anterior rectal wall, and rectal mucosa. The balloon also has a gas release valve enabling better patient comfort. Rectum localization enables the CyberKnife system to make fewer corrections resulting in fewer treatment interruptions and time lost to re-adjustment for rectal motion, bowel filling and gas creation. Effective treatment times are reduced by 25% to approximately 45 minutes. Adoption of the balloon has required minimal change to our planning strategy and plan evaluation process. Conclusion: Patient follow-up comparisons show no difference in effectiveness of treatment with and without balloons We conclude that rectal balloons enhance patient comfort and decrease effective treatment times.« less

  6. Exposure Dose Reconstruction from EPR Spectra of Tooth Enamel Exposed to the Combined Effect of X-rays and Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Kirillov, V. A.; Kuchuro, J. I.

    2014-09-01

    We have used EPR dosimetry on tooth enamel to show that the combined effect of x-rays with effective energy 34 keV and gamma radiation with average energy 1250 keV leads to a significant increase in the reconstructed absorbed dose compared with the applied dose from a gamma source or from an x-ray source or from both sources of electromagnetic radiation. In simulation experiments, we develop an approach to estimating the contribution of diagnostic x-rays to the exposure dose formed in the tooth enamel by the combined effect of x-rays and gamma radiation.

  7. Effect of Gamma Knife Radiosurgery and Programmed Cell Death 1 Receptor Antagonists on Metastatic Melanoma

    PubMed Central

    Hubbard, Molly; Nordmann, Tyler; Sperduto, Paul W; Clark, H. Brent; Hunt, Matthew A

    2017-01-01

    Learning objectives To evaluate radiation-induced changes in patients with brain metastasis secondary to malignant melanoma who received treatment with Gamma Knife radiosurgery (GKRS) and programmed cell death 1 (PD-1) receptor antagonists. Introduction  Stereotactic radiosurgery and chemotherapeutics are used together for treatment of metastatic melanoma and have been linked to delayed radiation-induced vasculitic leukoencephalopathy (DRIVL). There have been reports of more intense interactions with new immunotherapeutics targeting PD-1 receptors, but their interactions have not been well described and may result in an accelerated response to GKRS. Here we present data on subjects treated with this combination from a single institution. Methods Records from patients who underwent treatment for metastatic melanoma to the brain with GKRS from 2011 to 2016 were reviewed. Demographics, date of brain metastasis diagnosis, cause of death when applicable, immunotherapeutics, and imaging findings were recorded. The timing of radiation therapy and medications were also documented.  Results A total of 79 subjects were treated with GKRS, and 66 underwent treatment with both GKRS and immunotherapy. Regarding the 30 patients treated with anti-PD-1 immunotherapy, 21 patients received pembrolizumab, seven patients received nivolumab, and two patients received pembrolizumab and nivolumab. Serial imaging was available for interpretation in 25 patients, with 13 subjects who received GKRS and anti-PD-1 immunotherapy less than six weeks of each other. While four subjects had indeterminate/mixed findings on subsequent magnetic resonance imaging (MRI), nine subjects were noted to have progression. Two of these patients showed progression but subsequent imaging revealed a decrease in progression or improvement on MRI to previously targeted lesions by GKRS. None of the 13 subjects had surgery following their combined therapies. Conclusions This data suggests that there is need for

  8. Characterization of system-related geometric distortions in MR images employed in Gamma Knife radiosurgery applications.

    PubMed

    Pappas, E P; Seimenis, I; Moutsatsos, A; Georgiou, E; Nomikos, P; Karaiskos, P

    2016-10-07

    This work provides characterization of system-related geometric distortions present in MRIs used in Gamma Knife (GK) stereotactic radiosurgery (SRS) treatment planning. A custom-made phantom, compatible with the Leksell stereotactic frame model G and encompassing 947 control points (CPs), was utilized. MR images were obtained with and without the frame, thus allowing discrimination of frame-induced distortions. In the absence of the frame and following compensation for field inhomogeneities, measured average CP disposition owing to gradient nonlinearities was 0.53 mm. In presence of the frame, contrarily, detected distortion was greatly increased (up to about 5 mm) in the vicinity of the frame base due to eddy currents induced in the closed loop of its aluminum material. Frame-related distortion was obliterated at approximately 90 mm from the frame base. Although the region with the maximum observed distortion may not lie within the GK treatable volume, the presence of the frame results in distortion of the order of 1.5 mm at a 7 cm distance from the center of the Leksell space. Additionally, severe distortions observed outside the treatable volume could possibly impinge on the delivery accuracy mainly by adversely affecting the registration process (e.g. the position of the lower part of the N-shaped fiducials used to define the stereotactic space may be miss-registered). Images acquired with a modified version of the frame developed by replacing its front side with an acrylic bar, thus interrupting the closed aluminum loop and reducing the induced eddy currents, were shown to benefit from relatively reduced distortion. System-related distortion was also identified in patient MR images. Using corresponding CT angiography images as a reference, an offset of 1.1 mm was detected for two vessels lying in close proximity to the frame base, while excellent spatial agreement was observed for a vessel far apart from the frame base.

  9. Characterization of system-related geometric distortions in MR images employed in Gamma Knife radiosurgery applications

    NASA Astrophysics Data System (ADS)

    Pappas, E. P.; Seimenis, I.; Moutsatsos, A.; Georgiou, E.; Nomikos, P.; Karaiskos, P.

    2016-10-01

    This work provides characterization of system-related geometric distortions present in MRIs used in Gamma Knife (GK) stereotactic radiosurgery (SRS) treatment planning. A custom-made phantom, compatible with the Leksell stereotactic frame model G and encompassing 947 control points (CPs), was utilized. MR images were obtained with and without the frame, thus allowing discrimination of frame-induced distortions. In the absence of the frame and following compensation for field inhomogeneities, measured average CP disposition owing to gradient nonlinearities was 0.53 mm. In presence of the frame, contrarily, detected distortion was greatly increased (up to about 5 mm) in the vicinity of the frame base due to eddy currents induced in the closed loop of its aluminum material. Frame-related distortion was obliterated at approximately 90 mm from the frame base. Although the region with the maximum observed distortion may not lie within the GK treatable volume, the presence of the frame results in distortion of the order of 1.5 mm at a 7 cm distance from the center of the Leksell space. Additionally, severe distortions observed outside the treatable volume could possibly impinge on the delivery accuracy mainly by adversely affecting the registration process (e.g. the position of the lower part of the N-shaped fiducials used to define the stereotactic space may be miss-registered). Images acquired with a modified version of the frame developed by replacing its front side with an acrylic bar, thus interrupting the closed aluminum loop and reducing the induced eddy currents, were shown to benefit from relatively reduced distortion. System-related distortion was also identified in patient MR images. Using corresponding CT angiography images as a reference, an offset of 1.1 mm was detected for two vessels lying in close proximity to the frame base, while excellent spatial agreement was observed for a vessel far apart from the frame base.

  10. Natural soil gamma radioactivity levels and resultant population dose in the cities of Zacatecas and Guadalupe, Zacatecas, Mexico.

    PubMed

    Mireles, F; Dávila, J I; Quirino, L L; Lugo, J F; Pinedo, J L; Ríos, C

    2003-03-01

    The study of natural gamma radioactivity was made to determine the concentrations of natural radionuclides in soil. Twenty soil samples collected in the cities of Zacatecas and Guadalupe and their suburban areas in the Mexican state of Zacatecas were analyzed by gamma-ray spectrometry to determine the activity concentrations of 226Ra, 232Th, and 40K. Gamma-spectrometry measurements were made using a hyperpure germanium detector surrounded with shielding material to reduce the background counting rate. The GammaVision-32 MCA emulation software was used for gamma-ray spectrum analysis and the TRUMP card of 2k as a MCA emulator. Conversion factors were used to calculate the dose to the population from outdoor exposure to terrestrial gamma rays. The measured activity concentration of 226Ra varies from 11 to 38 Bq kg(-1), the activity concentration of 232Th varies from 8 to 38 Bq kg(-1). The activity concentration of 40K is in the range 309-1,049 Bq kg(-1). The overall population mean outdoor terrestrial gamma dose rate is 44.94 nGy h(-1).

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lucas, John T., E-mail: johnthomas75@gmail.com; Nida, Adrian M.; Isom, Scott

    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 proportionalmore » 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

  12. Gamma Knife Radiosurgery Treatment for Metastatic Melanoma of the Trigeminal Nerve and Brainstem: A Case Report and a Review of the Literature

    PubMed Central

    Peterson, Halloran E.; Larson, Erik W.; Fairbanks, Robert K.; Lamoreaux, Wayne T.; Mackay, Alexander R.; Call, Jason A.; Demakas, John J.; Cooke, Barton S.; Lee, Christopher M.

    2013-01-01

    Objective and Importance. Brainstem metastases (BSMs) are uncommon but serious complications of some cancers. They cause significant neurological deficit, and options for treatment are limited. Stereotactic radiosurgery (SRS) has been shown to be a safe and effective treatment for BSMs that prolongs survival and can preserve or in some cases improve neurological function. This case illustrates the use of repeated SRS, specifically Gamma Knife radiosurgery (GKRS) for management of a unique brainstem metastasis. Clinical Presentation. This patient presented 5 years after the removal of a lentigo maligna melanoma from her left cheek with left sided facial numbness and paresthesias with no reported facial weakness. Initial MRI revealed a mass on the left trigeminal nerve that appeared to be a trigeminal schwannoma. Intervention. After only limited response to the first GKRS treatment, a biopsy of the tumor revealed it to be metastatic melanoma, not schwannoma. Over the next two years, the patient would receive 3 more GKRS treatments. These procedures were effective in controlling growth in the treated areas, and the patient has maintained a good quality of life. Conclusion. GKRS has proven in this case to be effective in limiting the growth of this metastatic melanoma without acute adverse effects. PMID:24194991

  13. Diamond knife-assisted deep anterior lamellar keratoplasty to manage keratoconus.

    PubMed

    Vajpayee, Rasik B; Maharana, Prafulla K; Sharma, Namrata; Agarwal, Tushar; Jhanji, Vishal

    2014-02-01

    To evaluate the outcomes of a new surgical technique, diamond knife-assisted deep anterior lamellar keratoplasty (DALK), and compare its visual and refractive results with big-bubble DALK in cases of keratoconus. Tertiary eyecare hospital. Comparative case series. The visual and surgical outcomes of diamond knife-assisted DALK were compared with those of successful big-bubble DALK. Diamond knife-assisted DALK was performed in 19 eyes and big-bubble DALK, in 11 eyes. All surgeries were completed successfully. No intraoperative or postoperative complications occurred with diamond knife-assisted DALK. Six months after diamond knife-assisted DALK, the mean corrected distance visual acuity (CDVA) improved significantly from 1.87 logMAR ± 0.22 (SD) to 0.23 ± 0.06 logMAR, the mean keratometry improved from 65.99 ± 8.86 diopters (D) to 45.13 ± 1.16 D, and the mean keratometric cylinder improved from 7.99 ± 3.81 D to 2.87 ± 0.59 D (all P=.005). Postoperatively, the mean refractive astigmatism was 2.55 ± 0.49 D and the mean spherical equivalent was -1.97 ± 0.56 D. The mean logMAR CDVA (P = .06), postoperative keratometry (P=.64), refractive cylinder (P=.63), and endothelial cell loss (P=.11) were comparable between diamond knife-assisted DALK and big-bubble DALK. Diamond knife-assisted DALK was effective and predictable as a surgical technique for management of keratoconus cases. This technique has the potential to offer visual and refractive outcomes comparable to those of big-bubble DALK. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. [Induction of glutathione and activation of immune functions by low-dose, whole-body irradiation with gamma-rays].

    PubMed

    Kojima, Shuji

    2006-10-01

    We first examined the relation between the induction of glutathione and immune functions in mice after low-dose gamma-ray irradiation. Thereafter, inhibition of tumor growth by radiation was confirmed in Ehrlich solid tumor (EST)-bearing mice. The total glutathione level of the splenocytes transiently increased soon after irradiation and reached a maximum at around 4 h postirradiation. Thereafter, the level reverted to the 0 h value by 24 h postirradiation. A significantly high splenocyte proliferative response was also recognized 4 h postirradiation. Natural killer (NK) activity was also increased significantly in a similar manner. The time at which the response reached the maximum coincided well with that of maximum total glutathione levels of the splenocytes in the gamma-ray-irradiated mice. Reduced glutathione exogenously added to splenocytes obtained from normal mice enhanced the proliferative response and NK activity in a dose-dependent manner. The inhibitory effects of radiation on tumor growth was then examined in EST-bearing mice. Repeated low-dose irradiation (0.5 Gy, four times, before and within an early time after inoculation) significantly delayed the tumor growth. Finally, the effect of single low-dose (0.5 Gy), whole-body gamma-ray irradiation on immune balance was examined to elucidate the mechanism underlying the antitumor immunity. The percentage of B cells in blood lymphocytes was selectively decreased after radiation, concomitant with an increase in that of the helper T cell population. The IFN-gamma level in splenocyte culture prepared from EST-bearing mice was significantly increased 48 h after radiation, although the level of IL-4 was unchanged. IL-12 secretion from macrophages was also enhanced by radiation. These results suggest that low-dose gamma-rays induce Th1 polarization and enhance the activities of tumoricidal effector cells, leading to an inhibition of tumor growth.

  15. Analysis of gamma ray dose for dried up pond storing low enriched UO2 fuel

    NASA Astrophysics Data System (ADS)

    Nauchi, Yasushi; Suzuki, Motomu

    2017-09-01

    Gamma ray dose is calculated for loss of coolant accident in spent fuel pond (SFP) storing irradiated fuels used in light water reactors. Influence of modelling of fuel assemblies, source distributions, and loading fraction of fuel assemblies in the fuel rack on the dose are investigated.

  16. Monte Carlo calculation of the sensitivity of a commercial dose calibrator to gamma and beta radiation.

    PubMed

    Laedermann, Jean-Pascal; Valley, Jean-François; Bulling, Shelley; Bochud, François O

    2004-06-01

    The detection process used in a commercial dose calibrator was modeled using the GEANT 3 Monte Carlo code. Dose calibrator efficiency for gamma and beta emitters, and the response to monoenergetic photons and electrons was calculated. The model shows that beta emitters below 2.5 MeV deposit energy indirectly in the detector through bremsstrahlung produced in the chamber wall or in the source itself. Higher energy beta emitters (E > 2.5 MeV) deposit energy directly in the chamber sensitive volume, and dose calibrator sensitivity increases abruptly for these radionuclides. The Monte Carlo calculations were compared with gamma and beta emitter measurements. The calculations show that the variation in dose calibrator efficiency with measuring conditions (source volume, container diameter, container wall thickness and material, position of the source within the calibrator) is relatively small and can be considered insignificant for routine measurement applications. However, dose calibrator efficiency depends strongly on the inner-wall thickness of the detector.

  17. High dose gamma ray exposure effect on the properties of CdSe nanowires

    NASA Astrophysics Data System (ADS)

    Narula, Chetna; Chauhan, R. P.

    2018-03-01

    We report high dose gamma-ray (γ-ray) induced modifications incurred by polycrystalline cadmium selenide (CdSe) nanowires of 80 nm diameter. The nanowires have been synthesized using polycarbonate template assisted electro-deposition technique. The samples were irradiated with 60Co γ-radiation at a dose rate of 4.533 kGy/h for different time intervals with doses varying from 0 to 400 kGy. The effects of γ rays on the structural, morphological, optical and electrical properties of nanowires are discussed. XRD patterns of as-synthesized and gamma irradiated CdSe nanowires did not show any phase transformations but the variation in relative intensity was observed. The crystallite size evaluated using Scherrer's formula was found to vary. The optical parameters were obtained using UV-vis spectrometer measurements of absorption. Band gap was found to decrease with γ irradiation up to a dose of 300 kGy after which it was seen to increase. Refractive index and optical dielectric constants were also evaluated. Subjection of γ-radiation also brings about key changes in the electrical properties of CdSe nanowires. The attained data shows that the electrical conductivity varies with absorbed dose. The variations in the properties of CdSe nanowires can be considered as a consequence of ionization process, defect production and its annihilation.

  18. Usefulness of IT knife nano for endoscopic submucosal dissection of large colo-rectal lesions.

    PubMed

    Suzuki, T; Hara, T; Kitagawa, Y; Yamaguchi, T

    2016-01-01

    Endoscopic submucosal dissection (ESD) is currently widely conducted for the treatment of early gastrointestinal -cancers. Due to the characteristic anatomy of the large intestine, needle- tip type devices such as Dual knife are mainly used in colorectal ESD. On the other hand, the non- needle-tip type IT knife is a unique device with an insulated tip, and has been reported to be safe, efficacious and speedy when used in gastric ESD. A new model of IT knife, IT knife nano, anticipated to be useful for esophageal and colorectal ESD has become available, but its usefulness has not been reported. Therefore, we performed this study to evaluate the usefulness of IT knife nano for ESD of large colorectal lesions. Previous studies have shown that a tumor size of 40 mm or above significantly prolongs treatment time and is a factor of treatment difficulty. We selected colorectal lesions of 40 mm and above, and compared 32 lesions treated with Dual knife alone before IT knife nano was available (No-IT group) and 40 cases treated with IT knife nano as a second knife after IT knife nano became available (IT group). We assessed en bloc resection rate, complete en bloc resection rate, complication rate and treatment time. The en bloc resection rates in No-IT group and IT group were 100% and 97.5%, respectively, with no significant difference. The respective median treatment time was 70 min and 51 min, and was significantly shortened in IT group (P < 0.05). The respective rates of procedure- related perforation were 3.1% and 0% ; in IT group suggesting a tendency of reduced incidence. Use of IT knife nano in ESD for large colorectal -lesions achieves the same levels of efficacy and safety as conventional device, with the additional merit of shortening treatment time. © Acta Gastro-Enterologica Belgica.

  19. Endoscopic treatment of Zenker's diverticulum with the stag beetle knife (sb knife) - feasibility and follow-up.

    PubMed

    Goelder, S K; Brueckner, J; Messmann, H

    2016-10-01

    Flexible endoscopic treatment of symptomatic Zenker's diverticulum (ZD) is an established treatment option. This study reports the first large cohort of ZD patients treated with the stag beetle knife (sb knife, a new scissor-like device) regarding feasibility, safety, and sustainability of mucomyotomy using this technique. From August 2013 to January 2016, n = 52 patients (pts) were treated at Klinikum Augsburg, a tertiary referral center, with the sb knife junior or standard. For stability and safety, the septum is fixed with a soft overtube before intervention. Symptoms were analyzed before and at 1 and 6 months past intervention using an extensive questionnaire of dysphagia, odynophagia, regurgitation, chronic cough, state of health, and complications. The mean size of ZD was 3 cm (1-5 cm). Forty-seven out of 52 (90.4%) patients received one treatment session. The mean procedure time was 32 min (18-60 min). In 10 procedures (17%), a clip was placed at the bottom of the resection line. No major complications (e.g., perforation, mediastinitis) occurred. Five patients (9.6%) required a second treatment after a mean of 7 months (3-13) due to symptomatic recurrence. One patient was lost to further follow-up after one month with no or rare complaints. One patient had a third treatment (1.9%) without complications. During a mean follow-up of 16 months (2-31), the dysphagia score improved from 2 (1-4) prior of treatment to 1 (0-4), odynophagia, regurgitation, and chronic cough were no longer reported in the asymptomatic patients at all. Flexible endoscopic treatment of ZD with the sb knife and overtube is effective, safe, and has lasting effects with a relatively low recurrence rate.

  20. Tumor induction in mice after local irradiation with single doses of either carbon-ion beams or gamma rays.

    PubMed

    Ando, Koichi; Koike, Sachiko; Ohmachi, Yasushi; Ando, Yutaka; Kobashi, Gen

    2014-12-01

    To determine the dose-dependent relative biological effectiveness (RBE) for tumor prevalence in mice receiving single localized doses to their right leg of either carbon ions (15, 45 or 75 keV/μm) or 137Cs gamma rays. A total of 1647 female C3H mice were irradiated to their hind legs with a localized dose of either reference gamma rays or 15, 45 or 75 keV/μm carbon-ion beams. Irradiated mice were evaluated for tumors twice a month during their three-year life span, and the dimensions of any tumors found were measured with a caliper. The tumor induction frequency was calculated by Kaplan-Meier analysis. The incidence of tumors from 50 Gy of 45 keV/μm carbon ions was marginally higher than those from 50 Gy of gamma rays. However, 60 Gy of 15 keV/μm carbon ions induced significantly fewer tumors than did gamma rays. RBE values of 0.87 + 0.12, 1.29 + 0.08 or 2.06 + 0.39 for lifetime tumorigenesis were calculated for 15, 45 or 75 keV/μm carbon-ion beams, respectively. Fibrosarcoma predominated, with no Linear Energy Transfer (LET)-dependent differences in the tumor histology. Experiments measuring the late effect of leg skin shrinkage suggested that the carcinogenic damage of 15 keV/μm carbon ions would be less than that of gamma rays. We conclude that patients receiving radiation doses to their normal tissues would face less risk of secondary tumor induction by carbon ions of intermediate LET values compared to equivalent doses of photons.

  1. 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…

  2. Assessment of background gamma radiation levels using airborne gamma ray spectrometer data over uranium deposits, Cuddapah Basin, India - A comparative study of dose rates estimated by AGRS and PGRS.

    PubMed

    Srinivas, D; Ramesh Babu, V; Patra, I; Tripathi, Shailesh; Ramayya, M S; Chaturvedi, A K

    2017-02-01

    The Atomic Minerals Directorate for Exploration and Research (AMD) has conducted high-resolution airborne gamma ray spectrometer (AGRS), magnetometer and time domain electromagnetic (TDEM) surveys for uranium exploration, along the northern margins of Cuddapah Basin. The survey area includes well known uranium deposits such as Lambapur-Peddagattu, Chitrial and Koppunuru. The AGRS data collected for uranium exploration is utilised for estimating the average absorbed rates in air due to radio-elemental (potassium in %, uranium and thorium in ppm) distribution over these known deposit areas. Further, portable gamma ray spectrometer (PGRS) was used to acquire data over two nearby locations one from Lambapur deposit, and the other from known anomalous zone and subsequently average gamma dose rates were estimated. Representative in-situ rock samples were also collected from these two areas and subjected to radio-elemental concentration analysis by gamma ray spectrometer (GRS) in the laboratory and then dose rates were estimated. Analyses of these three sets of results complement one another, thereby providing a comprehensive picture of the radiation environment over these deposits. The average absorbed area wise dose rate level is estimated to be 130 ± 47 nGy h -1 in Lambapur-Peddagattu, 186 ± 77 nGy h -1 in Chitrial and 63 ± 22 nGy h -1 in Koppunuru. The obtained average dose levels are found to be higher than the world average value of 54 nGy h -1 . The gamma absorbed dose rates in nGy h -1 were converted to annual effective dose rates in mSv y -1 as proposed by the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). The annual average effective dose rates for the entire surveyed area is 0.12 mSv y -1 , which is much lower than the recommended limit of 1 mSv y -1 by International Commission on Radiation protection (ICRP). It may be ascertained here that the present study establishes a reference data set (baseline) in these areas

  3. MEASUREMENTS OF GAMMA-RAY DOSES OF DIFFERENT RADIOISOTOPES BY THE TEST-FILM METHOD (in German)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Domanus, J.; Halski, L.

    The test-film method seems to be most suitable for systematic, periodical measurements of individual doses of ionizing radiation. Persons handling radioisotopes are irradiated with gamma rays of different energies. The energy of gamma radiation lies within much broader limits than is the case with x rays. Therefore it was necessary to check whether the test-film method is suitable for measuring doses of gamma-rays of such different energies and to choose the proper combination of film and screen to reach the necessary measuring range. Polish films, Foton Rentgen and Foton Rentgen Super and films from the German Democratic Republic, Agfa Texomore » R and Agfa Texo S were tested. Expositions were made without intensifying screens as well as with lead and fluorescent screens. The investigations showed that for dosimetric purposes the Foton Rentgen Super films are most suitable. However, not one of the film-screen combinations gave satisfactory results for radioisotopes with radiation of different energies. In such a case the test-film method gives only approximate results. If, on the contrary, gamma energies do not differ greatly, the test- film method proves to be quite good. (auth)« less

  4. Longitudinal assessment of quality of life and audiometric test outcomes in vestibular schwannoma patients treated with gamma knife surgery.

    PubMed

    Park, Sean S; Grills, Inga Siiner; Bojrab, Dennis; Pieper, Daniel; Kartush, Jack; Maitz, Ann; Martin, Arturo; Perez, Evelyn; Hahn, Yoav; Ye, Hong; Martinez, Alvaro; Chen, Peter

    2011-06-01

    To prospectively assess the quality of life (QOL) and hearing acuity in vestibular schwannoma (VS) patients after gamma knife surgery (GKS). Fifty-nine VS patients. GKS. Prospective follow-up algorithm included 36-item Short Form Health Survey (SF-36), Hearing Handicap Inventory (HHI), Dizziness Handicap Inventory (DHI), Tinnitus Handicap Inventory (THI), pure-tone average, and speech discrimination hearing scores (Gardner-Robertson and American Academy of Otolaryngology), performed before and after GKS at 1-, 3-, 6-, 12-, and 18-month posttreatment intervals. From December 2006 to November 2008, 59 VS patients were treated with a median follow-up of 15 months. At baseline, mean scores for SF-36, HHI, DHI, and THI were 73, 37, 17, and 23, respectively. Median baseline Gardner-Robertson and American Academy of Otolaryngology hearing acuity scores were 2 and B, respectively. No significant decline in SF-36 health survey was noted after GKS. Mean SF-36 score at baseline was 73, compared with a range of 70 to 77 at predetermined posttreatment intervals. Similarly, no significant changes in DHI, HHI, and THI were noted. Approximately 47% of patients with baseline serviceable hearing maintained serviceable hearing at 12 months. Significant acute and chronic worsening in hearing acuity were noted at 1 and 18 months, respectively. No correlative decline in QOL was noted as assessed by SF-36 or HHI. No significant decline in global QOL occurred after GKS with relatively short follow-up and approximately 50% survey completion. When discussing therapy options with VS patients, anticipated treatment-related QOL outcomes should be considered.

  5. 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

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

    PubMed

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

    2015-05-21

    To determine the efficacy and safety of meticulous cannulation by needle-knife. 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. 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). 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.

  7. Protracted low-dose radiation priming and response of liver to acute gamma and proton radiation.

    PubMed

    Gridley, D S; Mao, X W; Cao, J D; Bayeta, E J M; Pecaut, M J

    2013-10-01

    This study evaluated liver from C57BL/6 mice irradiated with low-dose/low-dose-rate (LDR) γ-rays (0.01 Gy, 0.03 cGy/h), with and without subsequent exposure to acute 2 Gy gamma or proton radiation. Analyses were performed on day 56 post-exposure. Expression patterns of apoptosis-related genes were strikingly different among irradiated groups compared with 0 Gy (p < 0.05). Two genes were affected in the Gamma group, whereas 10 were modified in the LDR + Gamma group. In Proton and LDR + Proton groups, there were six and 12 affected genes, respectively. Expression of genes in the Gamma (Traf3) and Proton (Bak1, Birc2, Birc3, Mcl1) groups was no longer different from 0 Gy control group when mice were pre-exposed to LDR γ-rays. When each combined regimen was compared with the corresponding group that received acute radiation alone, two genes in the LDR + Gamma group and 17 genes in the LDR + Proton group were modified; greatest effect was on Birc2 and Nol3 (> 5-fold up-regulated by LDR + Protons). Oxygen radical production in livers from the LDR + Proton group was higher in LDR, Gamma, and LDR + Gamma groups (p < 0.05 vs. 0 Gy), but there were no differences in phagocytosis of E. coli. Sections stained with hematoxylin and eosin (H&E) suggested more inflammation, with and without necrosis, in some irradiated groups. The data demonstrate that response to acute radiation is dependent on radiation quality and regimen and that some LDR γ-ray-induced modifications in liver response were still evident nearly 2 months after exposure.

  8. Stereotactic radiosurgery in hemangioblastoma: Experience over 14 years

    PubMed Central

    Goyal, Nishant; Agrawal, Deepak; Singla, Raghav; Kale, Shashank Sharad; Singh, Manmohan; Sharma, Bhawani Shankar

    2016-01-01

    Background: Although gamma knife has been advocated for hemangioblastomas, it is not used widely by neurosurgeons. Objective: We review our experience over 14 years in an attempt to define the role of stereotactic radiosurgery (SRS) in the management of hemangioblastomas. Patients and Methods: A retrospective study was conducted on all patients of hemangioblastoma who underwent SRS at our institute over a period of 14 years (1998–2011). Gamma knife plans, clinical history, and radiology were reviewed for all patients. Results: A total of 2767 patients underwent gamma knife during the study period. Of these, 10 (0.36%) patients were treated for 24 hemangioblastomas. Eight patients (80%) had von Hippel-Lindau disease while two had sporadic hemangioblastomas. The median peripheral dose (50% isodose) delivered to the tumors was 29.9 Gy. Clinical and radiological follow-up data were available for eight patients. Of these, two were re-operated for persisting cerebellar symptoms. The remaining six patients were recurrence-free at a mean follow-up of 48 months (range 19–108 months). One patient had an increase in cyst volume along with a decrease in the size of the mural nodule. Conclusions: SRS should be the first option for asymptomatic hemangioblastomas. Despite the obvious advantages, gamma knife is not widely used as an option for hemangioblastomas. PMID:26933339

  9. Effective gamma-ray doses due to natural radiation from soils of southeastern Brazil

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Silveira, M. A. G.; Moreira, R. H.; Bellini, B. S.

    2010-08-04

    We have used gamma-ray spectrometry to study the distribution of natural radiation from soils of southeastern Brazil: Billings reservoir, Sao Bernardo do Campo Parks, Diadema Parks, Interlagos region, Sao Paulo, and soil from Sao Paulo and Rio de Janeiro beaches. In most of the regions studied we have found that the dose due the external exposure to gamma-rays, proceeding from natural terrestrial elements, are between the values 0.3 and 0.6 mSv/year, established by the United Nations Scientific Committee on the Effects of Atomic Radiation.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  11. Novel Concrete Chemistry Achieved with Low Dose Gamma Radiation Curing and Resistance to Neutron Activation

    NASA Astrophysics Data System (ADS)

    Burnham, Steven Robert

    As much as 50% of ageing-related problems with concrete structures can be attributed to con-struction deficiencies at the time of placement. The most influential time affecting longevity of concrete structures is the curing phase, or commonly the initial 28 days following its placement. A novel advanced atomistic analysis of novel concrete chemistry is presented in this dissertation with the objective to improve concrete structural properties and its longevity. Based on experiments and computational models, this novel concrete chemistry is discussed in two cases: (a) concrete chemistry changes when exposed to low-dose gamma radiation in its early curing stage, thus improving its strength in a shorter period of time then curing for the conventional 28 days; (b) concrete chemistry is controlled by its atomistic components to assure strength is not reduced but that its activation due to long-term exposure to neutron flux in nuclear power plants is negligible. High dose gamma radiation is well documented as a degradation mechanism that decreases concrete's compressive strength; however, the effects of low-dose gamma radiation on the initial curing phase of concrete, having never been studied before, proved its compressive strength increases. Using a 137 Cs source, concrete samples were subjected to gamma radiation during the initial curing phase for seven, 14, and 28 days. The compressive strength after seven days is improved for gamma cured concrete by 24% and after 14 days by 76%. Concrete shows no improvement in compressive strength after 28 days of exposure to gamma radiation, showing that there is a threshold effect. Scanning Electron Microscopy is used to examine the microstructure of low-dose gamma radiation where no damage to its microstructure is found, showing no difference between gamma cured and conventionally cured concrete. Molecular dynamics modeling based on the MOPAC package is used to study how gamma radiation during the curing stage improves

  12. Inverse modelling of radionuclide release rates using gamma dose rate observations

    NASA Astrophysics Data System (ADS)

    Hamburger, Thomas; Stohl, Andreas; von Haustein, Christoph; Thummerer, Severin; Wallner, Christian

    2014-05-01

    relatively sparse grid and the temporal resolution of available data may be low within the order of hours or a day. Gamma dose rates on the other hand are observed routinely on a much denser grid and higher temporal resolution. Gamma dose rate measurements contain no explicit information on the observed spectrum of radionuclides and have to be interpreted carefully. Nevertheless, they provide valuable information for the inverse evaluation of the source term due to their availability (Saunier et al., 2013). We present a new inversion approach combining an atmospheric dispersion model and observations of radionuclide activity concentrations and gamma dose rates to obtain the source term of radionuclides. We use the Lagrangian particle dispersion model FLEXPART (Stohl et al., 1998; Stohl et al., 2005) to model the atmospheric transport of the released radionuclides. The gamma dose rates are calculated from the modelled activity concentrations. The inversion method uses a Bayesian formulation considering uncertainties for the a priori source term and the observations (Eckhardt et al., 2008). The a priori information on the source term is a first guess. The gamma dose rate observations will be used with inverse modelling to improve this first guess and to retrieve a reliable source term. The details of this method will be presented at the conference. This work is funded by the Bundesamt für Strahlenschutz BfS, Forschungsvorhaben 3612S60026. References Davoine, X. and Bocquet, M., Atmos. Chem. Phys., 7, 1549-1564, 2007. Devell, L., et al., OCDE/GD(96)12, 1995. Eckhardt, S., et al., Atmos. Chem. Phys., 8, 3881-3897, 2008. Saunier, O., et al., Atmos. Chem. Phys., 13, 11403-11421, 2013. Stohl, A., et al., Atmos. Environ., 32, 4245-4264, 1998. Stohl, A., et al., Atmos. Chem. Phys., 5, 2461-2474, 2005. Stohl, A., et al., Atmos. Chem. Phys., 12, 2313-2343, 2012.

  13. Palliation of Postintubation Tracheal Stenosis Using Insulation-Tipped Diathermic Knife 2: A Case Report

    PubMed Central

    Yoon, Seon Bin; Park, Yong Won; Cheon, Mi Ju; Koh, Young Min; Park, Sanghoon; Kim, Se Joong; Lee, Seung Hyeun

    2015-01-01

    Objective To report the first case of using the insulation-tipped diathermic knife 2 (IT knife-2) for the treatment of postintubation tracheal stenosis. Clinical Presentation and Intervention A 71-year-old female patient with a history of endotracheal intubation 3 years earlier presented with throat discomfort, gross wheezing and dyspnea. Chest imaging and bronchoscopy demonstrated a strand-like tracheal stenosis in the upper trachea. The IT knife-2 was used to treat the patient and the lesion was palliated without complication. Conclusion This case was successfully treated with the IT knife-2 and thus implies a potential usefulness of the IT knife-2 as a new modality for bronchoscopic intervention. PMID:26390388

  14. Novel and Distinct Metabolites Identified Following a Single Oral Dose of Alpha- or Gamma-Hexabromocyclododecane in Mice

    EPA Science Inventory

    The metabolism of alpha- and gamma-hexabromocyclododecane (HBCD) was investigated in adult C57BL/6 female mice. Alpha- or gamma-[14C]HBCD (3 mg/kg bw) was orally administered with subsequent urine and feces collection for 4 consecutive days; a separate group of mice were dosed a...

  15. WE-AB-207B-01: Dose Tolerance for SBRT/SABR

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Grimm, J

    Purpose: Stereotactic body radiation therapy (SBRT) / stereotactic ablative body radiotherapy (SABR) is gaining popularity, but quantitative dose tolerance has still been lacking. To improve this, the April 2016 issue of Seminars in Radiation Oncology will have normal tissue complication probability (NTCP) models for 10 critical structures: optic pathway, cochlea, oral mucosa, esophagus, chestwall, aorta, bronchi, duodenum, small bowel, and spinal cord. Methods: The project included more than 1500 treatments in 1–5 fractions using CyberKnife, Gamma Knife, or LINAC, with 60 authors from 15 institutions. NTCP models were constructed from the 97 grade 2–3 complications, predominantly scored using the commonmore » terminology criteria for adverse events (CTCAEv4). Dose volume histogram (DVH) data from each institutional dataset was loaded into the DVH Evaluator software (DiversiLabs, LLC, Huntingdon Valley, Pa) for modeling. The current state of the literature for the critical structures was depicted using DVH Risk Maps: comparative graphs of dose tolerance limits that can include estimated risk levels, reported complications, DVH data for study patients, as well as high- and low-risk dose tolerance limits. Results: For relatively acceptable toxicity like grade 1–3 rib fractures and chestwall pain, the high-risk limits have 50% risk and the low-risk limits have 5% risk. Emami et al (IJROBP 1991 May 15;21(1):109–22) used 50% and 5% risk levels for all structures, whereas this effort used clinically acceptable ranges for each: in structures like aorta or spinal cord where complications must be avoided, the high- and low-risk limits have about 3% and 1% risk, respectively, in this issue of Seminars. These statistically based guidelines can help ensure plan quality for each patient. Conclusion: NTCP for SBRT is now becoming available. Hypofractionated dose tolerance can be dramatically different than extrapolations of conventional fractionation so NTCP analysis

  16. Objective assessment of knife sharpness over a working day cutting meat.

    PubMed

    Savescu, Adriana; Cuny-Guerrier, Aude; Wild, Pascal; Reno, Gilles; Aublet-Cuvelier, Agnès; Claudon, Laurent

    2018-04-01

    Knife sharpness is one of multiple factors involved in musculoskeletal disorders in industrial meat cutting. The aim of this study was to objectively evaluate, in real working situations, how knife sharpness changed over a working day cutting meat, and to analyse the impact of sharpening, steeling and meat-cutting activities on these variations. Twenty-two meat-cutting workers from three different companies participated in the study. The methods included measurements of knife sharpness in relation to real work situations and consideration of the way meat-cutting and sharpening operations were organised. Results showed that the type of meat-cutting activities, the steeling strategy adopted by the worker, including the types of tool used, and the overall organisation of the sharpening task all had a significant influence on how knife sharpness evolved over a 2-h period and over an entire working day. To improve MSD prevention, sharpening and steeling operations should not be considered as independent activities, but taken into account as a continuity of working actions. Appropriate assessment of knife sharpness by meat cutters affects how they organise meat-cutting and sharpening tasks. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. The journey from proton to gamma knife.

    PubMed

    Ganz, Jeremy C

    2014-01-01

    It was generally accepted by the early 1960s that proton beam radiosurgery was too complex and impractical. The need was seen for a new machine. The beam design had to be as good as a proton beam. It was also decided that a static design was preferable even if the evolution of that notion is no longer clear. Complex collimators were designed that using sources of cobalt-60 could produce beams with characteristics adequately close to those of proton beams. The geometry of the machine was determined including the distance of the sources from the patient the optimal distance between the sources. The first gamma unit was built with private money with no contribution from the Swedish state, which nonetheless required detailed design information in order to ensure radiation safety. This original machine was built with rectangular collimators to produce lesions for thalamotomy for functional work. However, with the introduction of dopamine analogs, this indication virtually disappeared overnight.

  18. Rat Phantom Depth Dose Studies in Electron, X-ray, Gamma-Ray, and Reactor Radiation Fields

    DTIC Science & Technology

    1986-12-01

    i©™D©/^ ^1[P@^T Rat phantom depth dose studies in electron , Xrayf gamma-ray, and reactor radiation fields M. Dooley D. M. Eagleson G. H. Zeman...energy electrons , bremsstrahlung, and mixed neutron/gamma radiation fields are sometimes used in radiobiological experiments employing rats. This report...have revealed differing sensitivities of experimental animals that have been exposed to cobalt-60 photons, high-energy electrons , high-energy X rays

  19. Endoscopic submucosal dissection for superficial esophageal neoplasms using the stag beetle knife.

    PubMed

    Fujinami, H; Hosokawa, A; Ogawa, K; Nishikawa, J; Kajiura, S; Ando, T; Ueda, A; Yoshita, H; Sugiyama, T

    2014-01-01

    Endoscopic submucosal dissection (ESD) is an accepted standard treatment for early gastric cancer but is not widely used in the esophagus because of technical difficulties. To increase the safety of esophageal ESD, we used a scissors-type device called the stag beetle (SB) knife. The aim of this study was to determine the efficacy and safety of ESD using the SB knife. We performed a single-center retrospective, uncontrolled trial. A total of 38 lesions were excised by ESD from 35 consecutive patients who were retrospectively divided into the following two groups according to the type of knife used to perform ESD: the hook knife (hook group) was used in 20 patients (21 lesions), and the SB knife (SB group) was used in 15 patients (17 lesions). We evaluated and compared the operative time, lesion size, en bloc resection rate, pathological margins free rate, and complication rate in both groups. The operative time was shorter in the SB group (median 70.0 minutes [interquartile range, 47.5-87.0]) than in the hook group (92.0 minutes [interquartile range, 63.0-114.0]) (P = 0.019), and the rate of complications in the SB group was 0% compared with 45.0% in the hook group (P = 0.004). However, the lesion size, en bloc resection rate, and pathological margins free rate did not differ significantly between the two groups. In conclusion, ESD using the SB knife was safer than that using a conventional knife for superficial esophageal neoplasms. © 2013 Wiley Periodicals, Inc. and the International Society for Diseases of the Esophagus.

  20. Assessment of Annual Effective Dose for Natural Radioactivity of Gamma Emitters in Biscuit Samples in Iraq.

    PubMed

    Abojassim, Ali Abid; Al-Alasadi, Lubna A; Shitake, Ahmed R; Al-Tememie, Faeq A; Husain, Afnan A

    2015-09-01

    Biscuits are an important type of food, widely consumed by babies in Iraq and other countries. This work uses gamma spectroscopy to measure the natural radioactivity due to long-lived gamma emitters in children's biscuits; it also estimates radiation hazard indices, that is, the radium equivalent activity, the representative of gamma level index, the internal hazard index, and the annual effective dose in children. Ten samples were collected from the Iraqi market from different countries of origin. The average specific activities for (226)Ra, (232)Th, and (40)K were 9.390, 3.1213, and 214.969 Bq/kg, respectively, but the average of the radium equivalent activity and the internal hazard index were 33.101 Bq/kg and 0.107, respectively. The total average annual effective dose from consumption by adults, children, and infants is estimated to be 0.655, 1.009, and 0.875 mSv, respectively. The values found for specific activity, radiation hazard indices, and annual effective dose in all samples in this study were lower than worldwide median values for all groups; therefore, these values are found to be safe.

  1. SU-F-T-266: Dynalogs Based Evaluation of Different Dose Rate IMRT Using DVH and Gamma Index

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ahmed, S; Ahmed, S; Ahmed, F

    2016-06-15

    Purpose: This work investigates the impact of low and high dose rate on IMRT through Dynalogs by evaluating Gamma Index and Dose Volume Histogram. Methods: The Eclipse™ treatment planning software was used to generate plans on prostate and head and neck sites. A range of dose rates 300 MU/min and 600 MU/min were applied to each plan in order to investigate their effect on the beam ON time, efficiency and accuracy. Each plan had distinct monitor units per fraction, delivery time, mean dose rate and leaf speed. The DVH data was used in the assessment of the conformity and planmore » quality.The treatments were delivered on Varian™ Clinac 2100C accelerator equipped with 120 leaf millennium MLC. Dynalogs of each plan were analyzed by MATLAB™ program. Fluence measurements were performed using the Sun Nuclear™ 2D diode array and results were assessed, based on Gamma analysis of dose fluence maps, beam delivery statistics and Dynalogs data. Results: Minor differences found by adjusted R-squared analysis of DVH’s for all the plans with different dose rates. It has been also found that more and larger fields have greater time reduction at high dose rate and there was a sharp decrease in number of control points observed in dynalog files by switching dose rate from 300 MU/min to 600 MU/min. Gamma Analysis of all plans passes the confidence limit of ≥95% with greater number of passing points in 300 MU/min dose rate plans. Conclusion: The dynalog files are compatible tool for software based IMRT QA. It can work perfectly parallel to measurement based QA setup and stand-by procedure for pre and post delivery of treatment plan.« less

  2. Estimation of radiation doses in TGFs and gamma ray glows

    NASA Astrophysics Data System (ADS)

    Celestin, S. J.; Pincon, J. L.; Trompier, F.

    2017-12-01

    Terrestrial gamma-ray flashes (TGFs) are bursts of high-energy photons originating from the Earth's atmosphere in association with thunderstorm activity [e.g., Briggs et al., JGR, 118, 3805, 2013]. TGFs are associated with initial propagation stages of intracloud lightning, which represent the most frequent type of lightning discharges [e.g., Cummer et al., GRL, 42, 7792, 2015, and references therein]. TGFs are known to be produced inside common thunderclouds [e.g., Splitt et al., JGR, 115, A00E38, 2010; Chronis et al., B. Am. Meteorol. Soc., 97, 639, 2016] typically at altitudes ranging from 10 to 14 km [e.g., Cummer et al., GRL, 41, 8586, 2014]. The global TGF occurrence rate is estimated to be 400,000 per year concerning TGFs detectable by Fermi-GBM (Gamma ray Burst Monitor) [Briggs et al., 2013], but detailed analysis of satellite measurements [Østgaard et al., JGR, 117, A03327, 2012] and theoretical studies [Celestin et al., JGR, 120, 10712, 2015] suggest that it cannot be excluded that TGFs represent a part of a regular process taking place during the propagation of lightning discharges. In addition to TGFs, another type of high-energy emissions has been observed inside thunderstorms from balloons [e.g., Eack et al., 101, 29637, 1996] and airplanes [e.g., McCarthy and Parks, 12, 393, 1985; Kelley et al., Nat. Commun., 6, 7845, 2015]. Referred to as gamma ray glows, these events correspond to significant elevations of the background radiation over long time scales that can be abruptly terminated with the occurrence of a lightning discharge. Kelley et al. [2015] estimate that a proportion larger than 8% of electrified storms produce glows. Dwyer et al. [JGR, 115, D09206, 2010] have estimated that if an aircraft were to find itself in the source electron beam giving rise to a TGF, passengers and crews might receive effective radiation doses above the regulatory limit depending on the beam diameter and Tavani et al. [Nat. Hazards Earth Syst. Sci., 13, 1127, 2013

  3. Knife wound to the posterior fossa in a child.

    PubMed

    Mohan, Avinash L; Slim, Michel; Benzil, Deborah L

    2005-03-01

    Knife wounds to the posterior fossa are a rare occurrence, especially in children. We report an 8-year-old girl who sustained a penetrating knife injury through the occipital bone into the posterior fossa. On presentation, the large knife blade was firmly embedded in her head. Radiographic evaluation was limited to plain X-rays because of the large size and sharpness of the embedded blade. Innovative positioning was used during intubation and then the patient was positioned semi-prone on the operating room table. The blade was surgically removed and the dura was closed. Atypical penetrating cranial injuries in children may require the treatment team to take a creative approach to the evaluation and repair of the lesion in order to maximize patient safety and minimize the risk of neurological injury.

  4. Effects of low-dose gamma-irradiation on production of shikonin derivatives in callus cultures of Lithospermum erythrorhizon S.

    NASA Astrophysics Data System (ADS)

    Chung, B. Y.; Lee, Y.-B.; Baek, M.-H.; Kim, J.-H.; Wi, S. G.; Kim, J.-S.

    2006-09-01

    The yield increase of secondary metabolite production was examined in plant cell cultures with the use of relatively low to high doses gamma irradiation. Suspension culture of Lithospermum erythrorhizon cells was irradiated to 2, 16, and 32 Gy. The gamma irradiation significantly stimulated the shikonin biosynthesis of the cells and increased the total shikonin yields (intracellular+extracellular shikonin yields) by 400% at 16 Gy and by only 240% and 180% at 2 and 32 Gy, respectively. One of the key enzymes for the shikonin biosynthesis of cells, p-hydroxylbenzoic acid (PHB) geranyltransferase, was found to be stimulated by the gamma-radiation treatments. The activity of PHB geranyltransferase was increased at 2 and 16 Gy with a negligible change at 32 Gy. In contrast, the activity of PHB glucosyltransferase was slightly changed at all doses of gamma radiation compared with the control cells. Therefore, the increase in PHB geranyltransferase activity leads to the accumulation of secondary metabolites such as a shikonin, which may contribute to plant defense against the stresses induced by gamma irradiation.

  5. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brezovich, I; Wu, X; Popple, R

    Purpose: To test spatial and dosimetric accuracy of small cranial target irradiation based on 1.5 T MRI scans using static arcs with MLC-defined fields Methods: A plastic (PMMA) phantom simulating a small brain lesion was mounted on a GammaKnife headframe equipped with MRI localizer. The lesion was a 3 mm long, 3.175 mm diameter cylindrical cavity filled with MRI contrast. Radiochromic film passing through the cavity was marked with pin pricks at the cavity center. The cavity was contoured on an MRI image and fused with CT to simulate treatment of a lesion not visible on CT. The transfer ofmore » the target to CT involved registering the MRI contrast cannels of the localizer that were visible on both modalities. Treatments were planned to deliver 800 cGy to the cavity center using multiple static arcs with 5.0×2.4 mm MLC-defined fields. The phantom was aligned on a STx accelerator by registering the conebeam CT with the planning CT. Films from coronal and sagittal planes were scanned and evaluated using ImageJ software Results: Geographic errors in treatment based on 1.5 T scans agreed within 0.33, −0.27 and 1.21 mm in the vertical, lateral and longitudinal dimensions, respectively. The doses delivered to the cavity center were 7.2% higher than planned. The dose distributions were similar to those of a GammaKnife. Conclusion: Radiation can be delivered with an accelerator at mm accuracy to small cranial targets based on 1.5 MRI scans fused to CTs using a standard GammaKnife headframe and MRI localizer. MLC-defined static arcs produce isodose lines very similar to the GammaKnife.« less

  6. Development of a multi-knife-edge slit collimator for prompt gamma ray imaging during proton beam cancer therapy

    NASA Astrophysics Data System (ADS)

    Ready, John Francis, III

    Proton beam usage to treat cancer has recently experienced rapid growth, as it offers the ability to target dose delivery in a patient more precisely than traditional x-ray treatment methods. Protons stop within the patient, delivering the maximum dose at the end of their track--a phenomenon described as the Bragg peak. However, because a large dose is delivered to a small volume, proton therapy is very sensitive to errors in patient setup and treatment planning calculations. Additionally, because all primary beam particles stop in the patient, there is no direct information available to verify dose delivery. These factors contribute to the range uncertainty in proton therapy, which ultimately hinders its clinical usefulness. A reliable method of proton range verification would allow the clinician to fully utilize the precise dose delivery of the Bragg peak. Several methods to verify proton range detect secondary emissions, especially prompt gamma ray (PG) emissions. However, detection of PGs is challenging due to their high energy (2-10 MeV) and low attenuation coefficients, which limit PG interactions in materials. Therefore, detection and collimation methods must be specifically designed for prompt gamma ray imaging (PGI) applications. In addition, production of PGs relies on delivering a dose of radiation to the patient. Ideally, verification of the Bragg peak location exposes patients to a minimal dose, thus limiting the PG counts available to the imaging system. An additional challenge for PGI is the lack of accurate simulation models, which limit the study of PG production characteristics and the relationship between PG distribution and dose delivery. Specific limitations include incorrect modeling of the reaction cross sections, gamma emission yields, and angular distribution of emission for specific photon energies. While simulations can still be valuable assets in designing a system to detect and image PGs, until new models are developed and incorporated

  7. Daily and Long Term Variations of Out-Door Gamma Dose Rate in Khorasan Province, Iran

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Toossi, M. T. Bahreyni; Bayani, SH.

    2008-08-07

    In Iran before 1996, only a few hot spots had been identified, no systematic study had been envisaged. Since then preparation of out-door environmental gamma radiation map of Iran was defined as a long term goal in our center, at the same time simultaneous monitoring of outdoor gamma level in Khorasan was also proposed. A Rados area monitoring system (AAM-90) including 10 intelligent RD-02 detector and all associated components were purchased. From 2003 gradually seven stations have been setup in Khorasan. For all seven stations monthly average and one hour daily average on four time intervals have been computed. Statisticallymore » no significant differences have been observed. This is also true for monthly averages. The overall average dose rate for present seven stations varies from 0.11 {mu}Sv{center_dot}h{sup -1} for Ferdows, to 0.04 {mu}Sv{center_dot}h{sup -1} for Dargaz. Based on our data, 50 minutes sample in any time interval is an accurate sample size to estimate out door Gamma dose rate.« less

  8. Evaluation of the stability of the stereotactic Leksell Frame G in Gamma Knife radiosurgery.

    PubMed

    Rojas-Villabona, Alvaro; Miszkiel, Katherine; Kitchen, Neil; Jäger, Rolf; Paddick, Ian

    2016-05-08

    The purpose of this study was to evaluate the stability of the Leksell Frame G in Gamma Knife radiosurgery (GKR). Forty patients undergoing GKR underwent pretreatment stereotactic MRI for GKR planning and stereotactic CT immediately after GKR. The stereotactic coordinates of four anatomical landmarks (cochlear apertures and the summits of the anterior post of the superior semicircular canals, bilaterally) were measured by two evaluators on two separate occasions in the pre-treatment MRI and post-treatment CT scans and the absolute distance between the observations is reported. The measurement method was validated with an indepen-dent group of patients who underwent both stereotactic MRI and CT imaging before treatment (negative controls; n: 5). Patients undergoing GKR for arteriovenous malformations (AVM) also underwent digital subtraction angiography (DSA), which could result in extra stresses on the frame. The distance between landmark local-ization in the scans for the negative control group (0.63 mm; 95% CI: 0.57-0.70; SD: 0.29) represents the overall consistency of the evaluation method and provides an estimate of the minimum displacement that could be detected by the study. Two patients in the study group had the fiducial indicator box accidentally misplaced at post-treatment CT scanning. This simulated the scenario of a frame displacement, and these cases were used as positive controls to demonstrate that the evaluation method is capable of detecting a discrepancy between the MRI and CT scans, if there was one. The mean distance between the location of the landmarks in the pretreatment MRI and post-treatment CT scans for the study group was 0.71 mm (95% CI: 0.68-0.74; SD:0.32), which was not statistically different from the over-all uncertainty of the evaluation method observed in the negative control group (p = 0.06). The subgroup of patients with AVM (n: 9), who also underwent DSA, showed a statistically significant difference between the location of the

  9. Postcontrast T1 Mapping for Differential Diagnosis of Recurrence and Radionecrosis after Gamma Knife Radiosurgery for Brain Metastasis.

    PubMed

    Wang, B; Zhang, Y; Zhao, B; Zhao, P; Ge, M; Gao, M; Ding, F; Xu, S; Liu, Y

    2018-06-01

    The differential diagnosis of radionecrosis and tumor recurrence in brain metastases is challenging. We investigated the diagnostic efficiency of postcontrast T1 mapping in solving this problem. Between March 2016 and June 2017, fifty-six patients with brain metastases who underwent contrast-enhanced cerebral T1 mapping were recruited for this prospective study. The findings revealed new enhancement after gamma knife radiosurgery. The subjects were assigned to radionecrosis and recurrence groups based on follow-up (median, 11.5 months) and histopathologic results. T1 values of lesions 5 (T1 5min ) and 60 (T1 60min ) minutes after administration of contrast agent and their difference (T1 differ ) were compared between the 2 groups with the 2-tailed Mann-Whitney U test. Receiver operating characteristic curves were used to determine the optimum cutoff values for differential diagnosis. There were significant differences between the 2 groups in T1 5min , T1 60min , and T1 differ values ( P = .012, P = .004, and P < .001, respectively). Relative to T1 5min and T1 60min , T1 differ exhibited greater sensitivity and specificity ( P < .001, respectively) in identifying radionecrosis. The optimum T1 differ value for differential diagnosis was 71.1 ms (area under the curve = 0.97; 95% CI, 0.93-1.00), with sensitivity and specificity of 81.5% and 96.5%, respectively. Postcontrast T1 mapping is optimal for the differential diagnosis of radionecrosis and tumor recurrence. Among T1 parameters, T1 differ is the most powerful parameter for differential diagnosis. Advantages in terms of quantitative analysis and high resolution portend the wide use of postcontrast T1 mapping in the future. © 2018 by American Journal of Neuroradiology.

  10. Retrospective analysis of imaging techniques for treatment planning and monitoring of obliteration for gamma knife treatment of cerebral arteriovenous malformation.

    PubMed

    Amponsah, Kwame; Ellis, Thomas L; Chan, Michael D; Lovato, James F; Bourland, J Daniel; deGuzman, Allan F; Ekstrand, Kenneth E; Munley, Michael T; McMullen, Kevin P; Shaw, Edward G; Tatter, Stephen B

    2012-10-01

    It has been well established that Gamma Knife radiosurgery (GKS) is an effective treatment for brain arteriovenous malformations (AVMs). To evaluate complete obliteration rates for magnetic resonance imaging (MRI)-based GKS treatment planning performed with and without angiography and to conduct a preliminary assessment of the utility of using pulsed arterial spin labeling (PASL) magnetic resonance (MR) perfusion imaging to confirm complete obliteration. Forty-six patients were identified who had undergone GKS without embolization with a minimum follow-up of 2 years. One group was planned with integrated stereotactic angiography and MR (spoiled gradient recalled) images obtained on the day of GKS. A second technique avoided the risk of arteriography by using only axial MR images. Beginning in 2007, PASL MR perfusion imaging was routinely performed as a portion of the follow-up MRI to assess the restoration of normal blood flow of the nidus and surrounding area. The overall obliteration rate for the angiography/MRI group was 88.0% (29 of 33). Patients in the MRI-only group had an obliteration rate of 61.5% (8 of 13), with P=.092 with the Fisher exact test, which is not statistically significant. A Kaplan-Meier analysis was also not statistically significant (log rank test, P=.474). Four of 9 patients with incomplete obliteration on angiography also had shown residual abnormal blood flow on PASL imaging. This retrospective analysis shows that treatment planning technique used in GKS does not play a role in the eventual obliteration of treated AVMs. PASL may have potential in the evaluation of AVM obliteration.

  11. Modeling gamma radiation dose in dwellings due to building materials.

    PubMed

    de Jong, Peter; van Dijk, Willem

    2008-01-01

    A model is presented that calculates the absorbed dose rate in air of gamma radiation emitted by building materials in a rectangular body construction. The basis for these calculations is formed by a fixed set of specific absorbed dose rates (the dose rate per Bq kg(-1) 238U, 232Th, and 40K), as determined for a standard geometry with the dimensions 4 x 5 x 2.8 m3. Using the computer codes Marmer and MicroShield, correction factors are assessed that quantify the influence of several room and material related parameters on the specific absorbed dose rates. The investigated parameters are the position in the construction; the thickness, density, and dimensions of the construction parts; the contribution from the outer leave; the presence of doors and windows; the attenuation by internal partition walls; the contribution from building materials present in adjacent rooms; and the effect of non-equilibrium due to 222Rn exhalation. To verify the precision, the proposed method is applied to three Dutch reference dwellings, i.e., a row house, a coupled house, and a gallery apartment. The averaged difference with MCNP calculations is found to be 4%.

  12. Some observations on glass-knife making.

    PubMed

    Ward, R T

    1977-11-01

    The yield of usable knife edge per knife (for thin sectioning) was markedly increased when glass knives were made at an included angle of 55 degrees rather than the customary 45 degrees. A large number of measurements of edge check marks made with a routine light scattering method as well as observations made on a smaller number of test sections with the electron microscope indicated the superiority of 55 degrees knives. Knives were made with both taped pliers and an LKB Knifemaker. Knives were graded by methods easily applied in any biological electron microscope laboratory. Depending on the mode of fracture, the yield of knives having more than 33% of their edges free of check marks was 30 to 100 times greater at 55 degrees than 45 degrees.

  13. Knife inflicted penetrating injuries of the maxillofacial region: a descriptive, record-based study.

    PubMed

    Meer, M; Siddiqi, A; Morkel, J A; Janse van Rensburg, P; Zafar, S

    2010-01-01

    Penetrating knife injuries of the face are more common in South Africa than the rest of the world. These injuries can be life-threatening, especially where the major blood vessels of the face are involved. The approach to treatment should be multidisciplinary, beginning with the trauma unit to provide airway maintenance and haemodynamic stabilisation. An interventional radiologist may be consulted for angiography. The aim of the present study was to retrospectively analyse all cases of knife-inflicted penetrating injuries to the maxillofacial region with the knife in situ and subsequently develop a management protocol to be used by maxillofacial surgery registrars when presented with such cases. It was a retrospective, cross-sectional and record-based study, analysing all penetrating knife injuries reported at various hospitals for a period of 11 years. In this study, 24 cases of knife injuries were analysed. Twenty-one patients (87.5%) in this series were male and three (12.5%) were female. Of these 24 patients, 13 (54.2%) were coloured and 11 (45.8%) were black. There were no white or Indian patients. Post-surgical recovery of all patients was rapid and uneventful, and there were no fatalities. Patients with knife injuries to the face with no definite signs of vascular injury can thus be safely and accurately managed on the basis of physical examination and plain-film radiography. An angiogram is mandatory if the patient presents with excessive bleeding, an expanding haematoma or if the knife blade is in the region of any large vessels.

  14. Critical appraisal of RapidArc radiosurgery with flattening filter free photon beams for benign brain lesions in comparison to GammaKnife: a treatment planning study.

    PubMed

    Abacioglu, Ufuk; Ozen, Zeynep; Yilmaz, Meltem; Arifoglu, Alptekin; Gunhan, Basri; Kayalilar, Namik; Peker, Selcuk; Sengoz, Meric; Gurdalli, Salih; Cozzi, Luca

    2014-05-21

    To evaluate the role of RapidArc (RA) for stereotactic radiosurgery (SRS) of benign brain lesions in comparison to GammaKnife (GK) based technique. Twelve patients with vestibular schwannoma (VS, n = 6) or cavernous sinus meningioma (CSM, n = 6) were planned for both SRS using volumetric modulated arc therapy (VMAT) by RA. 104 MV flattening filter free photon beams with a maximum dose rate of 2400 MU/min were selected. Data were compared against plans optimised for GK. A single dose of 12.5 Gy was prescribed. The primary objective was to assess treatment plan quality. Secondary aim was to appraise treatment efficiency. For VS, comparing best GK vs. RA plans, homogeneity was 51.7 ± 3.5 vs. 6.4 ± 1.5%; Paddick conformity Index (PCI) resulted 0.81 ± 0.03 vs. 0.84 ± 0.04. Gradient index (PGI) was 2.7 ± 0.2 vs. 3.8 ± 0.6. Mean target dose was 17.1 ± 0.9 vs. 12.9 ± 0.1 Gy. For the brain stem, D(1cm3) was 5.1 ± 2.0 Gy vs 4.8 ± 1.6 Gy. For the ipsilateral cochlea, D(0.1cm3) was 1.7 ± 1.0 Gy vs. 1.8 ± 0.5 Gy. For CSM, homogeneity was 52.3 ± 2.4 vs. 12.4 ± 0.6; PCI: 0.86 ± 0.05 vs. 0.88 ± 0.05; PGI: 2.6 ± 0.1 vs. 3.8 ± 0.5; D(1cm3) to brain stem was 5.4 ± 2.8 Gy vs. 5.2 ± 2.8 Gy; D(0.1cm3) to ipsi-lateral optic nerve was 4.2 ± 2.1 vs. 2.1 ± 1.5 Gy; D(0.1cm3) to optic chiasm was 5.9 ± 3.1 vs. 4.5 ± 2.1 Gy. Treatment time was 53.7 ± 5.8 (64.9 ± 24.3) minutes for GK and 4.8 ± 1.3 (5.0 ± 0.7) minutes for RA for schwannomas (meningiomas). SRS with RA and FFF beams revealed to be adequate and comparable to GK in terms of target coverage, homogeneity, organs at risk sparing with some gain in terms of treatment efficiency.

  15. Critical appraisal of RapidArc radiosurgery with flattening filter free photon beams for benign brain lesions in comparison to GammaKnife: a treatment planning study

    PubMed Central

    2014-01-01

    Background To evaluate the role of RapidArc (RA) for stereotactic radiosurgery (SRS) of benign brain lesions in comparison to GammaKnife (GK) based technique. Methods Twelve patients with vestibular schwannoma (VS, n = 6) or cavernous sinus meningioma (CSM, n = 6) were planned for both SRS using volumetric modulated arc therapy (VMAT) by RA. 104 MV flattening filter free photon beams with a maximum dose rate of 2400 MU/min were selected. Data were compared against plans optimised for GK. A single dose of 12.5 Gy was prescribed. The primary objective was to assess treatment plan quality. Secondary aim was to appraise treatment efficiency. Results For VS, comparing best GK vs. RA plans, homogeneity was 51.7 ± 3.5 vs. 6.4 ± 1.5%; Paddick conformity Index (PCI) resulted 0.81 ± 0.03 vs. 0.84 ± 0.04. Gradient index (PGI) was 2.7 ± 0.2 vs. 3.8 ± 0.6. Mean target dose was 17.1 ± 0.9 vs. 12.9 ± 0.1 Gy. For the brain stem, D1cm3 was 5.1 ± 2.0 Gy vs 4.8 ± 1.6 Gy. For the ipsilateral cochlea, D0.1cm3 was 1.7 ± 1.0 Gy vs. 1.8 ± 0.5 Gy. For CSM, homogeneity was 52.3 ± 2.4 vs. 12.4 ± 0.6; PCI: 0.86 ± 0.05 vs. 0.88 ± 0.05; PGI: 2.6 ± 0.1 vs. 3.8 ± 0.5; D1cm3 to brain stem was 5.4 ± 2.8 Gy vs. 5.2 ± 2.8 Gy; D0.1cm3 to ipsi-lateral optic nerve was 4.2 ± 2.1 vs. 2.1 ± 1.5 Gy; D0.1cm3 to optic chiasm was 5.9 ± 3.1 vs. 4.5 ± 2.1 Gy. Treatment time was 53.7 ± 5.8 (64.9 ± 24.3) minutes for GK and 4.8 ± 1.3 (5.0 ± 0.7) minutes for RA for schwannomas (meningiomas). Conclusions SRS with RA and FFF beams revealed to be adequate and comparable to GK in terms of target coverage, homogeneity, organs at risk sparing with some gain in terms of treatment efficiency. PMID:24884967

  16. 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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nicolato, Antonio; Lupidi, Francesco; Section of Stereotactic and Functional Neurosurgery, University of Verona and University Hospital, Verona

    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 =more » 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.« less

  17. Outcome of peroral endoscopic myotomy in achalasia cardia: Experience with a new triangular knife.

    PubMed

    Nabi, Zaheer; Ramchandani, Mohan; Chavan, Radhika; Kalapala, Rakesh; Darisetty, Santosh; Reddy, D Nageshwar

    2018-01-01

    Peroral endoscopic myotomy (POEM) is a technically demanding procedure. Recently, a new triangular knife with integrated water jet function (TTJ) has been introduced. The present study was aimed to analyze and compare the operating time, efficacy, and adverse events (AEs) between the conventional (TT knife) and new knife (TTJ). All patients with achalasia cardia (AC) who underwent POEM between August 2015 and November 2016 were analyzed retrospectively. Operating time (OT), technical success, and AEs were assessed and compared between TT and TTJ knife. A total of 193 patients with AC underwent POEM during the specified period. Both groups had equivalent number of different subtypes of AC (I, II, and III). There was no difference in technical success between the two groups (TT, 99% vs TT, 98.9%). OT was significantly less in the TTJ group as compared to TT group (53.8 ± 15.2 vs 66.26 ± 19.2; P = 0.0001). On subanalysis, OT taken for submucosal tunneling was significantly less with TTJ knife (34.6 ± 10.1 vs 45.83 ± 14.80), whereas OT was similar for myotomy and clipping in both the groups. Significantly fewer use of coagulation forceps and exchanges of accessories were required in TTJ knife group (2.92 ± 1.77 vs 10.5 ± 3.58; P = 0.0001). There were no major AEs. Minor AEs were noted in 21.5% and 31% of patients in TTJ and TT knife groups, respectively. New triangular knife reduces procedure time and technical difficulty with POEM. POEM is an efficacious treatment for achalasia and can be safely executed in an endoscopy unit.

  18. Integration of Functional Magnetic Resonance Imaging and Magnetoencephalography Functional Maps Into a CyberKnife Planning System: Feasibility Study for Motor Activity Localization and Dose Planning.

    PubMed

    De Martin, Elena; Duran, Dunja; Ghielmetti, Francesco; Visani, Elisa; Aquino, Domenico; Marchetti, Marcello; Sebastiano, Davide Rossi; Cusumano, Davide; Bruzzone, Maria Grazia; Panzica, Ferruccio; Fariselli, Laura

    2017-12-01

    Magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) provide noninvasive localization of eloquent brain areas for presurgical planning. The aim of this study is the integration of MEG and fMRI maps into a CyberKnife (CK) system to optimize dose planning. Four patients with brain metastases in the motor area underwent functional imaging study of the hand motor cortex before radiosurgery. MEG data were acquired during a visually cued hand motor task. Motor activations were identified also using an fMRI block-designed paradigm. MEG and fMRI maps were then integrated into a CK system and contoured as organs at risk for treatment planning optimization. The integration of fMRI data into the CK system was achieved for all patients by means of a standardized protocol. We also implemented an ad hoc pipeline to convert the MEG signal into a DICOM standard, to make sure that it was readable by our CK treatment planning system. Inclusion of the activation areas into the optimization plan allowed the creation of treatment plans that reduced the irradiation of the motor cortex yet not affecting the brain peripheral dose. The availability of advanced neuroimaging techniques is playing an increasingly important role in radiosurgical planning strategy. We successfully imported MEG and fMRI activations into a CK system. This additional information can improve dose sparing of eloquent areas, allowing a more comprehensive investigation of the related dose-volume constraints that in theory could translate into a gain in tumor local control, and a reduction of neurological complications. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Observation of Phase Objects by Using an X-ray Microscope with a Foucault Knife-Edge

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Watanabe, N.; Sasaya, T.; Imai, Y.

    2011-09-09

    An x-ray microscope with a zone plate was assembled at the synchrotron radiation source of BL3C, Photon Factory. A Foucault knife-edge was set at the back focal plate of the objective zone plate and phase retrieval was tested by scanning the knife-edge. A preliminary result shows that scanning the knife-edge during exposure was effective for phase retrieval. Phase-contrast tomography was investigated using differential projection images calculated from two Schlieren images with the oppositely oriented knife-edges. Fairly good reconstruction images of polystyrene beads and spores could be obtained.

  20. Induction and disappearance of G2 chromatid breaks in lymphocytes after low doses of low-LET gamma-rays and high-LET fast neutrons.

    PubMed

    Vral, A; Thierens, H; Baeyens, A; De Ridder, L

    2002-04-01

    To determine by means of the G2 assay the number of chromatid breaks induced by low-LET gamma-rays and high-LET neutrons, and to compare the kinetics of chromatid break rejoining for radiations of different quality. The G2 assay was performed on blood samples of four healthy donors who were irradiated with low-LET gamma-rays and high-LET neutrons. In a first set of experiments a dose-response curve for the formation of chromatid breaks was carried out for gamma-rays and neutrons with doses ranging between 0.1 and 0.5 Gy. In a second set of experiments, the kinetics of chromatid break formation and disappearance were investigated after a dose of 0.5 Gy using post-irradiation times ranging between 0.5 and 3.5 h. For the highest dose of 0.5 Gy, the number of isochromatid breaks was also scored. No significant differences in the number of chromatid breaks were observed between low-LET gamma-rays and high-LET neutrons for the four donors at any of the doses given. The dose-response curves for the formation of chromatid breaks are linear for both radiation qualities and RBEs = 1 were obtained. Scoring of isochromatid breaks at the highest dose of 0.5 Gy revealed that high-LET neutrons were, however, more effective at inducing isochromatid breaks (RBE = 6.2). The rejoining experiments further showed that the kinetics of disappearance of chromatid breaks following irradiation with low-LET gamma-rays or high-LET neutrons were not significantly different. Half-times of 0.92 h for gamma-rays and 0.84 h for neutrons were obtained. Applying the G2 assay, the results demonstrate that at low doses of irradiation, the induction as well as the disappearance of chromatid breaks is independent of the LET of the radiation qualities used (0.24 keV x microm(-1) 60Co gamma-rays and 20 keV x microm(-1) fast neutrons). As these radiation qualities produce the same initial number of double-strand breaks, the results support the signal model that proposes that chromatid breaks are the result

  1. Differentially Expressed Genes Associated with Low-Dose Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Hegyesi, Hargita; Sándor, Nikolett; Schilling, Boglárka; Kis, Enikő; Lumniczky, Katalin; Sáfrány, Géza

    We have studied low dose radiation induced gene expression alterations in a primary human fibroblast cell line using Agilent's whole human genome microarray. Cells were irradiated with 60Co γ-rays (0; 0.1; 0.5 Gy) and 2 hours later total cellular RNA was isolated. We observed differential regulation of approximately 300-500 genes represented on the microarray. Of these, 126 were differentially expressed at both doses, among them significant elevation of GDF-15 and KITLG was confirmed by qRT-PCR. Based on the transcriptional studies we selected GDF-15 to assess its role in radiation response, since GDF-15 is one of the p53 gene targets and is believed to participate in mediating p53 activities. First we confirmed gamma-radiation induced dose-dependent changes in GDF-15 expression by qRT-PCR. Next we determined the effect of GDF-15 silencing on radiosensitivity. Four GDF-15 targeting shRNA expressing lentiviral vectors were transfected into immortalized human fibroblast cells. We obtained efficient GDF-15 silencing in one of the four constructs. RNA interference inhibited GDF-15 gene expression and enhanced the radiosensitivity of the cells. Our studies proved that GDF-15 plays an essential role in radiation response and may serve as a promising target in radiation therapy.

  2. Thermal welding vs. cold knife tonsillectomy: a comparison of voice and speech.

    PubMed

    Celebi, Saban; Yelken, Kursat; Celik, Oner; Taskin, Umit; Topak, Murat

    2011-01-01

    To compare acoustic, aerodynamic and perceptual voice and speech parameters in thermal welding system tonsillectomy and cold knife tonsillectomy patients in order to determine the impact of operation technique on voice and speech. Thirty tonsillectomy patients (22 children, 8 adults) participated in this study. The preferred technique was cold knife tonsillectomy in 15 patients and thermal welding system tonsillectomy in the remaining 15 patients. One week before and 1 month after surgery the following parameters were estimated: average of fundamental frequency, Jitter, Shimmer, harmonic to noise ratio, formant frequency analyses of sustained vowels. Perceptual speech analysis and aerodynamic measurements (maximum phonation time and s/z ratio) were also conducted. There was no significant difference in any of the parameters between cold knife tonsillectomy and thermal welding system tonsillectomy groups (p>0.05). When the groups were contrasted among themselves with regards to preoperative and postoperative rates, fundamental frequency was found to be significantly decreased after tonsillectomy in both of the groups (p<0.001). First formant for the vowel /a/ in the cold knife tonsillectomy group and for the vowel /i/ in the thermal welding system tonsillectomy group, second formant for the vowel /u/ in the thermal welding system tonsillectomy group and third formant for the vowel /u/ in the cold knife tonsillectomy group were found to be significantly decreased (p<0.05). The surgical technique, whether it is cold knife or thermal welding system, does not appear to affect voice and speech in tonsillectomy patients. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  3. Knife-edge seal for vacuum bagging

    NASA Technical Reports Server (NTRS)

    Rauschl, J. A.

    1980-01-01

    Cam actuated clamps pinch bagging material between long knife edge (mounted to clamps) and high temperature rubber cushion bonded to baseplate. No adhesive, tape, or sealing groove is needed to seal edge of bagging sheet against base plate.

  4. Management of Liver Cancer Argon-helium Knife Therapy with Functional Computer Tomography Perfusion Imaging.

    PubMed

    Wang, Hongbo; Shu, Shengjie; Li, Jinping; Jiang, Huijie

    2016-02-01

    The objective of this study was to observe the change in blood perfusion of liver cancer following argon-helium knife treatment with functional computer tomography perfusion imaging. Twenty-seven patients with primary liver cancer treated with argon-helium knife and were included in this study. Plain computer tomography (CT) and computer tomography perfusion (CTP) imaging were conducted in all patients before and after treatment. Perfusion parameters including blood flows, blood volume, hepatic artery perfusion fraction, hepatic artery perfusion, and hepatic portal venous perfusion were used for evaluating therapeutic effect. All parameters in liver cancer were significantly decreased after argon-helium knife treatment (p < 0.05 to all). Significant decrease in hepatic artery perfusion was also observed in pericancerous liver tissue, but other parameters kept constant. CT perfusion imaging is able to detect decrease in blood perfusion of liver cancer post-argon-helium knife therapy. Therefore, CTP imaging would play an important role for liver cancer management followed argon-helium knife therapy. © The Author(s) 2014.

  5. 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.

  6. Outcome of peroral endoscopic myotomy in achalasia cardia: Experience with a new triangular knife

    PubMed Central

    Nabi, Zaheer; Ramchandani, Mohan; Chavan, Radhika; Kalapala, Rakesh; Darisetty, Santosh; Reddy, D. Nageshwar

    2018-01-01

    Background and Aim: Peroral endoscopic myotomy (POEM) is a technically demanding procedure. Recently, a new triangular knife with integrated water jet function (TTJ) has been introduced. The present study was aimed to analyze and compare the operating time, efficacy, and adverse events (AEs) between the conventional (TT knife) and new knife (TTJ). Patients and Methods: All patients with achalasia cardia (AC) who underwent POEM between August 2015 and November 2016 were analyzed retrospectively. Operating time (OT), technical success, and AEs were assessed and compared between TT and TTJ knife. Results: A total of 193 patients with AC underwent POEM during the specified period. Both groups had equivalent number of different subtypes of AC (I, II, and III). There was no difference in technical success between the two groups (TT, 99% vs TT, 98.9%). OT was significantly less in the TTJ group as compared to TT group (53.8 ± 15.2 vs 66.26 ± 19.2; P = 0.0001). On subanalysis, OT taken for submucosal tunneling was significantly less with TTJ knife (34.6 ± 10.1 vs 45.83 ± 14.80), whereas OT was similar for myotomy and clipping in both the groups. Significantly fewer use of coagulation forceps and exchanges of accessories were required in TTJ knife group (2.92 ± 1.77 vs 10.5 ± 3.58; P = 0.0001). There were no major AEs. Minor AEs were noted in 21.5% and 31% of patients in TTJ and TT knife groups, respectively. Conclusion: New triangular knife reduces procedure time and technical difficulty with POEM. POEM is an efficacious treatment for achalasia and can be safely executed in an endoscopy unit. PMID:29451180

  7. Safety and efficacy of Gamma Knife radiosurgery in hypothalamic hamartomas with severe epilepsies: A prospective trial in 48 patients and review of the literature.

    PubMed

    Régis, Jean; Lagmari, Medhi; Carron, Romain; Hayashi, Motohiro; McGonigal, Aileen; Daquin, Géraldine; Villeneuve, Nathalie; Laguitton, Virginie; Bartolomei, Fabrice; Chauvel, Patrick

    2017-06-01

    Epilepsies associated with hypothalamic hamartomas (HHs) are frequently drug resistant with severe psychiatric and cognitive comorbidities. We performed a prospective trial to evaluate the safety and efficacy of Gamma Knife radiosurgery (GKS). Between October 1999 and October 2007, a total of 57 patients were investigated, included and treated by GKS in Timone University Hospital. Preoperative workup and 3-year postoperative evaluation consisted of seizure diary, neuropsychological, psychiatric, endocrinologic, visual field, and visual acuity examinations. Follow-up of >3 years was available for 48 patients. Topologic type was type I in 11 patients, type II in 15, type III in 17, type IV in one, type V in one, type VI in one, and mixed type in 2. The median marginal dose was 17 Gy (min 14 and max 25 Gy). The median target volume was 398 mm 3 (28-1,600 mm 3 ). Due to partial results, 28 patients (58.3%) required a second treatment. The median follow-up was 71 months (36-153 months). At last follow-up, the rate of Engel class I outcome was 39.6%, Engel class II was 29.2% (I+II 68.8%), and Engel class III was 20%. Global psychiatric comorbidity was considered cured in 28%, improved in 56%, stable in 8%, and continued to worsen in 8%. No permanent neurologic side effect was reported (in particular, no memory deficit). Nondisabling transient poikilothermia was observed in three patients (6.2%). A transient increase of seizure frequency was reported in 8 patients (16.6%) with a median duration of 30 days (9-90 days). Microsurgery was proposed because of insufficient efficacy of GKS in seven patients (14.5%) with a postoperative Engel class I-II in 28.6%. This prospective trial demonstrates very good long-term safety and efficacy of GKS for 2 patients. Beyond seizure reduction, the improvement of psychiatric and cognitive comorbidities along with better school performance and social functioning, being better socially integrated, having friends having a social life

  8. Neutron flux and gamma dose measurement in the BNCT irradiation facility at the TRIGA reactor of the University of Pavia

    NASA Astrophysics Data System (ADS)

    Bortolussi, S.; Protti, N.; Ferrari, M.; Postuma, I.; Fatemi, S.; Prata, M.; Ballarini, F.; Carante, M. P.; Farias, R.; González, S. J.; Marrale, M.; Gallo, S.; Bartolotta, A.; Iacoviello, G.; Nigg, D.; Altieri, S.

    2018-01-01

    University of Pavia is equipped with a TRIGA Mark II research nuclear reactor, operating at a maximum steady state power of 250 kW. It has been used for many years to support Boron Neutron Capture Therapy (BNCT) research. An irradiation facility was constructed inside the thermal column of the reactor to produce a sufficient thermal neutron flux with low epithermal and fast neutron components, and low gamma dose. In this irradiation position, the liver of two patients affected by hepatic metastases from colon carcinoma were irradiated after borated drug administration. The facility is currently used for cell cultures and small animal irradiation. Measurements campaigns have been carried out, aimed at characterizing the neutron spectrum and the gamma dose component. The neutron spectrum has been measured by means of multifoil neutron activation spectrometry and a least squares unfolding algorithm; gamma dose was measured using alanine dosimeters. Results show that in a reference position the thermal neutron flux is (1.20 ± 0.03) ×1010 cm-2 s-1 when the reactor is working at the maximum power of 250 kW, with the epithermal and fast components, respectively, 2 and 3 orders of magnitude lower than the thermal component. The ratio of the gamma dose with respect to the thermal neutron fluence is 1.2 ×10-13 Gy/(n/cm2).

  9. Low-dose gamma-ray irradiation induces translocation of Nrf2 into nuclear in mouse macrophage RAW264.7 cells.

    PubMed

    Tsukimoto, Mitsutoshi; Tamaishi, Nana; Homma, Takujiro; Kojima, Shuji

    2010-01-01

    The transcription factor nuclear erythroid-derived 2-related factor 2 (Nrf2) regulates expression of genes encoding antioxidant proteins involved in cellular redox homeostasis, while gamma-ray irradiation is known to induce reactive oxygen species in vivo. Although activation of Nrf2 by various stresses has been studied, it has not yet been determined whether ionizing irradiation induces activation of Nrf2. Therefore, we investigated activation of Nrf2 in response to gamma-irradiation in mouse macrophage RAW264.7 cells. Irradiation of cells with gamma-rays induced an increase of Nrf2 expression. Even 0.1 Gy of gamma-irradiation induced a translocation of Nrf2 from cytoplasm to the nucleus, indicating the activation of Nrf2 by low-dose irradiation. Expression of heme oxygenase-1, which is regulated by Nrf2, was also increased at 24 h after irradiation with more than 0.1 Gy of gamma-rays. Furthermore, the activation of Nrf2 was suppressed by U0126, which is an inhibitor of the extracellular signal regulated protein kinase 1/2 (ERK1/2) pathway, suggesting involvement of ERK1/2-dependent pathway in the irradiation-induced activation of Nrf2. Our results indicate that low-dose gamma-irradiation induces activation of Nrf2 through ERK1/2-dependent pathways.

  10. SU-E-T-594: Out-Of-Field Neutron and Gamma Dose Estimated Using TLD-600/700 Pairs in the Wobbling Proton Therapy System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Y; Lin, Y; Medical Physics Research Center, Institute for Radiological Research, Chang Gung University / Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan

    Purpose: Secondary fast neutrons and gamma rays are mainly produced due to the interaction of the primary proton beam with the beam delivery nozzle. These secondary radiation dose to patients and radiation workers are unwanted. The purpose of this study is to estimate the neutron and gamma dose equivalent out of the treatment volume during the wobbling proton therapy system. Methods: Two types of thermoluminescent (TL) dosimeters, TLD-600 ({sup 6}LiF: Mg, Ti) and TLD-700 ({sup 7}LiF: Mg, Ti) were used in this study. They were calibrated in the standard neutron and gamma sources at National Standards Laboratory. Annealing procedure ismore » 400°C for 1 hour, 100°C for 2 hours and spontaneously cooling down to the room temperature in a programmable oven. Two-peak method (a kind of glow curve analysis technique) was used to evaluate the TL response corresponding to the neutron and gamma dose. The TLD pairs were placed outside the treatment field at the neutron-gamma mixed field with 190-MeV proton beam produced by the wobbling system through the polyethylene plate phantom. The results of TLD measurement were compared to the Monte Carlo simulation. Results: The initial experiment results of calculated dose equivalents are 0.63, 0.38, 0.21 and 0.13 mSv per Gy outside the field at the distance of 50, 100, 150 and 200 cm. Conclusion: The TLD-600 and TLD-700 pairs are convenient to estimate neutron and gamma dosimetry during proton therapy. However, an accurate and suitable glow curve analysis technique is necessary. During the wobbling system proton therapy, our results showed that the neutron and gamma doses outside the treatment field are noticeable. This study was supported by the grants from the Chang Gung Memorial Hospital (CMRPD1C0682)« less

  11. Interest of submucosal dissection knife for endoscopic treatment of Zenker's diverticulum.

    PubMed

    Laquière, A; Grandval, P; Arpurt, J P; Boulant, J; Belon, S; Aboukheir, S; Laugier, R; Penaranda, G; Curel, L; Boustière, C

    2015-09-01

    Dual-Knife(®) (Olympus) and Hydride-Knife(®) are new needle knives frequently used for submucosal dissection because of their safety and precision. In this study we aimed to evaluate the efficacy and safety of such devices in the diverticulopexy by flexible endoscopy. From February 2009 to March 2013, 42 patients (25 men), mean age 74.5, with symptomatic Zenker's diverticulum, were included in a non-randomized prospective multicenter study. The symptoms described by all patients include dysphagia, regurgitation and/or swallowing disorders. The diverticulopexy was performed with the Dual-Knife(®) or Hydrid-Knife(®), after septum exposure with the diverticuloscope, and terminated with distal tip clips positioning. All complications were noted. Patients' symptoms were regularly assessed during follow-up visits or telephone interviews. The first endoscopy treatment was successful for all patients. Thirty-seven patients (88%) had symptoms improvement after the first treatment. The recurrence rate was 14% (6 patients); a second endoscopic treatment was required 12 months on average after the first treatment, with 100% efficiency. Mid-term (16 months) efficiency was 91.67% after 1 to 3 endoscopic treatments. A total of 55 procedures were performed without perforation or significant bleeding and 3 patients underwent surgery. In multivariate analysis, the diverticulum size and the type of dissection knife were not risks factors for recurrence. Endoscopic diverticuloscope-assisted diverticulotomy with submucosal dissection knives is a safe and effective alternative treatment for patients with a symptomatic Zenker's diverticulum measuring between 2 and 10 cm.

  12. Influence on grip of knife handle surface characteristics and wearing protective gloves.

    PubMed

    Claudon, Laurent

    2006-11-01

    Ten subjects were asked to apply maximum torques on knife handles with either their bare hand or their hand wearing a Kevlar fibre protective glove. Four knife handles (2 roughnesses, 2 hardnesses) were tested. Surface electromyograms of 6 upper limb and shoulder muscles were recorded and subject opinions on both knife handle hardness and friction in the hand were also assessed. The results revealed the significant influence of wearing gloves (p<0.0001), knife type (p<0.0005) and handle hardness (p<0.005) on the applied torque. Wearing Kevlar fibre gloves greatly increased the torque independently of the other two parameters. Under the bare hand condition, a 90 degrees ShA slightly rough handle provided the greatest torque. Subject opinion agreed with the observed effects on recorded torque values except for the hardness factor, for which a preference for the 70 degrees ShA value over the 90 degrees ShA value emerged.

  13. [Treatment of trigger finger with located needle knife].

    PubMed

    Zhang, Qi-Feng; Yang, Jiang; Xi, Sheng-Hua

    2016-07-25

    To investigate the clinical effects of located needle knife in the treatment of trigger finger. The clinical data of 133 patients(145 fingers) with trigger finger underwent treatment with located needle knife from September 2010 to March 2014 were retrospectively analyzed. There were 37 males(40 fingers) and 96 females (105 fingers), aged from 18 to 71 years old with a mean of 51.8 years. Course of disease was from 1 to 19 months with an average of 8.2 months. Affected fingers included 82 thumbs, 12 index fingers, 11 middle fingers, 36 ring fingers, and 4 little fingers. According to the standard of Quinnell grade, 42 fingers were grade III, 92 fingers were grade IV, and 11 fingers were grade V. Firstly the double pipe gab was put into the distal edge of hypertrophic tendon sheath, then small knife needle was used to release the sheath proximally along the tendon line direction. The informations of wound healing and nerve injury, postoperative finger function, finger pain at 6 months were observed. The operation time was from 8 to 25 min with an average of 9.8 min. All the patients were followed up from 6 to 26 months with an average of 12.5 months. No complications such as the wound inflammation and seepage, vascular or nerve injuries were found. According to the standard of Quinnell grade, 123 fingers got excellent results, 15 good, 7 poor. It's a good choice to treat trigger finger with located needle knife in advantage of minimal invasion, simple safe operation, and it should be promoted in clinic.

  14. A retracting wire knife for cutting fiber bundles and making sheet lesions of brain tissue.

    PubMed

    Shibata, M; Russell, I S

    1979-07-01

    A retracting knife which has two cutting wires for the transection of fiber bundles is described. The knife holds the fiber bundles of the stria terminalis between the two cutting wires and transects them by a shearing movement as the wires close. In addition, the feasability of such a knife producing a sheet lesion around the n. caudatus is also described.

  15. Novel design and sensitivity analysis of displacement measurement system utilizing knife edge diffraction for nanopositioning stages.

    PubMed

    Lee, ChaBum; Lee, Sun-Kyu; Tarbutton, Joshua A

    2014-09-01

    This paper presents a novel design and sensitivity analysis of a knife edge-based optical displacement sensor that can be embedded with nanopositioning stages. The measurement system consists of a laser, two knife edge locations, two photodetectors, and axillary optics components in a simple configuration. The knife edge is installed on the stage parallel to its moving direction and two separated laser beams are incident on knife edges. While the stage is in motion, the direct transverse and diffracted light at each knife edge is superposed producing interference at the detector. The interference is measured with two photodetectors in a differential amplification configuration. The performance of the proposed sensor was mathematically modeled, and the effect of the optical and mechanical parameters, wavelength, beam diameter, distances from laser to knife edge to photodetector, and knife edge topography, on sensor outputs was investigated to obtain a novel analytical method to predict linearity and sensitivity. From the model, all parameters except for the beam diameter have a significant influence on measurement range and sensitivity of the proposed sensing system. To validate the model, two types of knife edges with different edge topography were used for the experiment. By utilizing a shorter wavelength, smaller sensor distance and higher edge quality increased measurement sensitivity can be obtained. The model was experimentally validated and the results showed a good agreement with the theoretically estimated results. This sensor is expected to be easily implemented into nanopositioning stage applications at a low cost and mathematical model introduced here can be used for design and performance estimation of the knife edge-based sensor as a tool.

  16. Pleuroscopic punch biopsy using insulated-tip diathermic knife-2 for the diagnosis of desmoplastic malignant mesothelioma.

    PubMed

    Masai, Kyohei; Sasada, Shinji; Izumo, Takehiro; Taniyama, Tomoko; Nakamura, Yukiko; Chavez, Christine; Sakurai, Hiroyuki; Tsuta, Koji; Tsuchida, Takaaki

    2013-10-01

    Desmoplastic malignant mesothelioma (DMM) is a rare subtype of malignant pleural mesothelioma (MPM) and is often difficult to distinguish from pleural fibrosis and reactive mesothelial hyperplasia, especially if the biopsy samples are small. We performed full-thickness pleural biopsy on a lesion suspected to be DMM using an insulated-tip diathermic knife-2 (IT knife-2) during flex-rigid pleuroscopy. IT knife-2 is a novel electrosurgical device for endoscopic submucosal dissection in the early gastrointestinal cancer. It consists of a needle knife with 3 short blades at the distal end attached to an insulated ceramic tip. A 54-year-old man presenting with chest wall mass and thickened pleura, in whom a computed tomography-guided percutaneous needle aspiration had remained negative, underwent flex-rigid pleuroscopy for definitive diagnosis. While applying electric current, we used the IT knife-2 to incise the pleura in a circular shape just above the endothoracic fascia. The incised pleura was removed by forceps and examined pathologically. The microscopic examination was compatible with DMM. We discovered that pleuroscopic punch biopsy using IT knife-2 can diagnose DMM. Use of IT knife-2 during flex-rigid pleuroscopy can obtain sufficient samples from densely thickened pleura, which is difficult to diagnose with small biopsies.

  17. Ultralow-dose, feedback imaging with laser-Compton X-ray and laser-Compton gamma ray sources

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barty, Christopher P. J.

    Ultralow-dose, x-ray or gamma-ray imaging is based on fast, electronic control of the output of a laser-Compton x-ray or gamma-ray source (LCXS or LCGS). X-ray or gamma-ray shadowgraphs are constructed one (or a few) pixel(s) at a time by monitoring the LCXS or LCGS beam energy required at each pixel of the object to achieve a threshold level of detectability at the detector. An example provides that once the threshold for detection is reached, an electronic or optical signal is sent to the LCXS/LCGS that enables a fast optical switch that diverts, either in space or time the laser pulsesmore » used to create Compton photons. In this way, one prevents the object from being exposed to any further Compton x-rays or gamma-rays until either the laser-Compton beam or the object are moved so that a new pixel location may be illumination.« less

  18. Extracranial Facial Nerve Schwannoma Treated by Hypo-fractionated CyberKnife Radiosurgery.

    PubMed

    Sasaki, Ayaka; Miyazaki, Shinichiro; Hori, Tomokatsu

    2016-09-21

    Facial nerve schwannoma is a rare intracranial tumor. Treatment for this benign tumor has been controversial. Here, we report a case of extracranial facial nerve schwannoma treated successfully by hypo-fractionated CyberKnife (Accuray, Sunnyvale, CA) radiosurgery and discuss the efficacy of this treatment. A 34-year-old female noticed a swelling in her right mastoid process. The lesion enlarged over a seven-month period, and she experienced facial spasm on the right side. She was diagnosed with a facial schwannoma via a magnetic resonance imaging (MRI) scan of the head and neck and was told to wait until the facial nerve palsy subsides. She was referred to our hospital for radiation therapy. We planned a fractionated CyberKnife radiosurgery for three consecutive days. After CyberKnife radiosurgery, the mass in the right parotid gradually decreased in size, and the facial nerve palsy disappeared. At her eight-month follow-up, her facial spasm had completely disappeared. There has been no recurrence and the facial nerve function has been normal. We successfully demonstrated the efficacy of CyberKnife radiosurgery as an alternative treatment that also preserves neurofunction for facial nerve schwannomas.

  19. Submillisecond Optical Knife-Edge Testing

    NASA Technical Reports Server (NTRS)

    Thurlow, P.

    1983-01-01

    Fast computer-controlled sampling of optical knife-edge response (KER) signal increases accuracy of optical system aberration measurement. Submicrosecond-response detectors in optical focal plane convert optical signals to electrical signals converted to digital data, sampled and feed into computer for storage and subsequent analysis. Optical data are virtually free of effects of index-of-refraction gradients.

  20. Long-Term Survival in a Patient with Multiple Brain Metastases from Small-Cell Lung Cancer Treated with Gamma Knife Radiosurgery on Four Occasions: A Case Report

    PubMed Central

    Elaimy, Ameer L.; Thumma, Sudheer R.; Lamm, Andrew F.; Mackay, Alexander R.; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Demakas, John J.; Cooke, Barton S.; Lee, Christopher M.

    2012-01-01

    Brain metastases are the most common cancerous neoplasm in the brain. The treatment of these lesions is challenging and often includes a multimodality management approach with whole-brain radiation therapy, stereotactic radiosurgery, and neurosurgery options. Although advances in biomedical imaging technologies and the treatment of extracranial cancer have led to the overall increase in the survival of brain metastases patients, the finding that select patients survive several years remains puzzling. For this reason, we present the case of a 70-year-old patient who was diagnosed with multiple brain metastases from small-cell lung cancer five years ago and is currently alive following treatment with chemotherapy for the primary cancer and whole-brain radiation therapy and Gamma Knife radiosurgery on four separate occasions for the neurological cancer. Since the diagnosis of brain metastases five years ago, the patient's primary cancer has remained controlled. Furthermore, multiple repeat GKRS procedures provided this patient with high levels of local tumor control, which in combination with a stable primary cancer led to an extended period of survival and a highly functional life. Further analysis and clinical research will be valuable in assessing the durability of multiple GKRS for brain metastases patients who experience long-term survival. PMID:23091748

  1. Poster - 49: Assessment of Synchrony respiratory compensation error for CyberKnife liver treatment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Ming; Cygler,

    The goal of this work is to quantify respiratory motion compensation errors for liver tumor patients treated by the CyberKnife system with Synchrony tracking, to identify patients with the smallest tracking errors and to eventually help coach patient’s breathing patterns to minimize dose delivery errors. The accuracy of CyberKnife Synchrony respiratory motion compensation was assessed for 37 patients treated for liver lesions by analyzing data from system logfiles. A predictive model is used to modulate the direction of individual beams during dose delivery based on the positions of internally implanted fiducials determined using an orthogonal x-ray imaging system and themore » current location of LED external markers. For each x-ray pair acquired, system logfiles report the prediction error, the difference between the measured and predicted fiducial positions, and the delivery error, which is an estimate of the statistical error in the model overcoming the latency between x-ray acquisition and robotic repositioning. The total error was calculated at the time of each x-ray pair, for the number of treatment fractions and the number of patients, giving the average respiratory motion compensation error in three dimensions. The 99{sup th} percentile for the total radial error is 3.85 mm, with the highest contribution of 2.79 mm in superior/inferior (S/I) direction. The absolute mean compensation error is 1.78 mm radially with a 1.27 mm contribution in the S/I direction. Regions of high total error may provide insight into features predicting groups of patients with larger or smaller total errors.« less

  2. A comparison of two prompt gamma imaging techniques with collimator-based cameras for range verification in proton therapy

    NASA Astrophysics Data System (ADS)

    Lin, Hsin-Hon; Chang, Hao-Ting; Chao, Tsi-Chian; Chuang, Keh-Shih

    2017-08-01

    In vivo range verification plays an important role in proton therapy to fully utilize the benefits of the Bragg peak (BP) for delivering high radiation dose to tumor, while sparing the normal tissue. For accurately locating the position of BP, camera equipped with collimators (multi-slit and knife-edge collimator) to image prompt gamma (PG) emitted along the proton tracks in the patient have been proposed for range verification. The aim of the work is to compare the performance of multi-slit collimator and knife-edge collimator for non-invasive proton beam range verification. PG imaging was simulated by a validated GATE/GEANT4 Monte Carlo code to model the spot-scanning proton therapy and cylindrical PMMA phantom in detail. For each spot, 108 protons were simulated. To investigate the correlation between the acquired PG profile and the proton range, the falloff regions of PG profiles were fitted with a 3-line-segment curve function as the range estimate. Factors including the energy window setting, proton energy, phantom size, and phantom shift that may influence the accuracy of detecting range were studied. Results indicated that both collimator systems achieve reasonable accuracy and good response to the phantom shift. The accuracy of range predicted by multi-slit collimator system is less affected by the proton energy, while knife-edge collimator system can achieve higher detection efficiency that lead to a smaller deviation in predicting range. We conclude that both collimator systems have potentials for accurately range monitoring in proton therapy. It is noted that neutron contamination has a marked impact on range prediction of the two systems, especially in multi-slit system. Therefore, a neutron reduction technique for improving the accuracy of range verification of proton therapy is needed.

  3. Experimental study of hybrid-knife endoscopic submucosal dissection (ESD) versus standard ESD in a Western country.

    PubMed

    De-la-Peña, Joaquín; Calderón, Ángel; Esteban, José Miguel; López-Rosés, Leopoldo; Martínez-Ares, David; Nogales, Óscar; Orive-Calzada, Aitor; Rodríguez, Sarbelio; Sánchez-Hernández, Eloy; Vila, Juan; Fernández-Esparrach, Gloria

    2014-02-01

    Endoscopic submucosal dissection (ESD) is an effective but time-consuming treatment for early neoplasia that requires a high level of expertise. The objective of this study was to assess the efficacy and learning curve of gastric ESD with a hybrid knife with high pressure water jet and to compare with standard ESD. We performed a prospective non survival animal study comparing hybrid-knife and standard gastric ESD. Variables recorded were: Number of en-bloc ESD, number of ESD with all marks included (R0), size of specimens, time and speed of dissection and adverse events. Ten endoscopists performed a total of 50 gastric ESD (30 hybrid-knife and 20 standard). Forty-six (92 %) ESD were en-bloc and 25 (50 %) R0 (hybrid-knife: n = 13, 44 %; standard: n = 16, 80 %; p = 0.04). Hybrid-knife ESD was faster than standard (time: 44.6 +/- 21.4 minutes vs. 68.7 +/- 33.5 minutes; p = 0.009 and velocity: 20.8 +/- 9.2 mm(2)/min vs. 14.3 +/- 9.3 mm(2)/min (p = 0.079). Adverse events were not different. There was no change in speed with any of two techniques (hybrid-knife: From 20.33 +/- 15.68 to 28.18 +/- 20.07 mm(2)/min; p = 0.615 and standard: From 6.4 +/- 0.3 to 19.48 +/- 19.21 mm(2)/min; p = 0.607). The learning curve showed a significant improvement in R0 rate in the hybrid-knife group (from 30 % to 100 %). despite the initial performance of hybrid-knife ESD is worse than standard ESD, the learning curve with hybrid knife ESD is short and is associated with a rapid improvement. The introduction of new tools to facilitate ESD should be implemented with caution in order to avoid a negative impact on the results.

  4. Thermoluminescence glow-curve characteristics of LiF phosphors at high doses of gamma radiation

    NASA Astrophysics Data System (ADS)

    Benny, P. G.; Khader, S. A.; Sarma, K. S. S.

    2013-05-01

    High doses of ionising radiation are becoming increasingly common for radiation-processing applications of various medical, agricultural and polymer products using gamma and electron beams. The objective of this work was to study thermoluminescence (TL) glow-curve characteristics of commonly used commercial LiF TL phosphors at high doses of radiation with a view to use them in dosimetry of radiation-processing applications. The TL properties of TLD 100 and 700 phosphors, procured from the Thermo-Scientific (previously Harshaw) company, have been studied in the dose range of 1-60 kGy. The shift in glow peaks was observed in this dose range. Integral TL responses of TLD 100 and TLD 700 were found to decrease as a linear function of dose in the range of 5-50 kGy. The paper describes initial results related to the glow-curve characteristics of these phosphors.

  5. Image processing techniques revealing the relationship between the field-measured ambient gamma dose equivalent rate and geological conditions at a granitic area, Velence Mountains, Hungary

    NASA Astrophysics Data System (ADS)

    Beltran Torres, Silvana; Petrik, Attila; Zsuzsanna Szabó, Katalin; Jordan, Gyozo; Szabó, Csaba

    2017-04-01

    In order to estimate the annual dose that the public receive from natural radioactivity, the identification of the potential risk areas is required which, in turn, necessitates understanding the relationship between the spatial distribution of natural radioactivity and the geogenic risk factors (e.g., rock types, dykes, faults, soil conditions, etc.). A detailed spatial analysis of ambient gamma dose equivalent rate was performed in the western side of Velence Mountains, the largest outcropped granitic area in Hungary. In order to assess the role of local geology in the spatial distribution of ambient gamma dose rates, field measurements were carried out at ground level at 300 sites along a 250 m x 250 m regular grid in a total surface of 14.7 km2. Digital image processing methods were applied to identify anomalies, heterogeneities and spatial patterns in the measured gamma dose rates, including local maxima and minima determination, digital cross sections, gradient magnitude and gradient direction, second derivative profile curvature, local variability, lineament density, 2D autocorrelation and directional variogram analyses. Statistical inference showed that different gamma dose rate levels are associated with the rock types (i.e., Carboniferous granite, Pleistocene colluvial, proluvial, deluvial sediments and talus, and Pannonian sand and pebble), with the highest level on the Carboniferous granite including outlying values. Moreover, digital image processing revealed that linear gamma dose rate spatial features are parallel to the SW-NE dyke system and possibly to the NW-SE main fractures. The results of this study underline the importance of understanding the role of geogenic risk factors influencing the ambient gamma dose rate received by public. The study also demonstrates the power of the image processing techniques for the identification of spatial pattern in field-measured geogenic radiation.

  6. A cross-sectional study of knife injuries at a London major trauma centre.

    PubMed

    Pallett, J R; Sutherland, E; Glucksman, E; Tunnicliff, M; Keep, J W

    2014-01-01

    No national recording systems for knife injuries exist in the UK. Understanding the true size and nature of the problem of knife injuries is the first stage in reducing the burden of this injury. The aim of this study was to survey every knife injury seen in a single inner city emergency department (ED) over a one-year period. A cross-sectional observational study was performed of all patients attending with a knife injury to the ED of a London major trauma centre in 2011. Demographic characteristics, patterns of injury, morbidity and mortality data were collected. A total of 938 knife injuries were identified from 127,191 attendances (0.77% of all visits) with a case fatality rate of 0.53%. A quarter (24%) of the major trauma team's caseload was for knife injuries. Overall, 44% of injuries were selfreported as assaults, 49% as accidents and 8% as deliberate self-harm. The highest age specific incident rate occurred in the 16-24 year age category (263/100,000). Multiple injuries were seen in 19% of cases, of which only 81% were recorded as assaults. The mean length of stay for those admitted to hospital was 3.04 days. Intrathoracic injury was seen in 26% of cases of chest trauma and 24% of abdominal injuries had a second additional chest injury. Violent intentional injuries are a significant contributory factor to the workload of the major trauma team at this centre. This paper contributes to a more comprehensive understanding of the nature of these injuries seen in the ED.

  7. Gamma-ray spectra and doses from the Little Boy replica

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moss, C.E.; Lucas, M.C.; Tisinger, E.W.

    1984-01-01

    Most radiation safety guidelines in the nuclear industry are based on the data concerning the survivors of the nuclear explosions at Hiroshima and Nagasaki. Crucial to determining these guidelines is the radiation from the explosions. We have measured gamma-ray pulse-height distributions from an accurate replica of the Little Boy device used at Hiroshima, operated at low power levels near critical. The device was placed outdoors on a stand 4 m from the ground to minimize environmental effects. The power levels were based on a monitor detector calibrated very carefully in independent experiments. High-resolution pulse-height distributions were acquired with a germaniummore » detector to identify the lines and to obtain line intensities. The 7631 to 7645 keV doublet from neutron capture in the heavy steel case was dominant. Low-resolution pulse-height distributions were acquired with bismuth-germanate detectors. We calculated flux spectra from these distributions using accurately measured detector response functions and efficiency curves. We then calculated dose-rate spectra from the flux spectra using a flux-to-dose-rate conversion procedure. The integral of each dose-rate spectrum gave an integral dose rate. The integral doses at 2 m ranged from 0.46 to 1.03 mrem per 10/sup 13/ fissions. The output of the Little Boy replica can be calculated with Monte Carlo codes. Comparison of our experimental spectra, line intensities, and integral doses can be used to verify these calculations at low power levels and give increased confidence to the calculated values from the explosion at Hiroshima. These calculations then can be used to establish better radiation safety guidelines. 7 references, 7 figures, 2 tables.« less

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

    USDA-ARS?s Scientific Manuscript database

    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,...

  9. Radioactivity Levels and Gamma-Ray Dose Rate in Soil Samples from Kohistan (Pakistan) Using Gamma-Ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Hasan, M. Khan; Ismail, M.; K., Khan; Akhter, P.

    2011-01-01

    The analysis of naturally occurring radionuclides (226Ra, 232Th and 40K) and an anthropogenic radionuclide 137Cs is carried out in some soil samples collected from Kohistan district of N.W.F.P. (Pakistan), using gamma-ray spectrometry. The gamma spectrometry is operated using a high purity Germanium (HPGe) detector coupled with a computer based high resolution multi channel analyzer. The specific activity in soil ranges from 24.72 to 78.48Bq·kg-1 for 226Ra, 21.73 to 75.28Bq·kg-1 for 232Th, 7.06 to 14.9Bq·kg-1 for 137Cs and 298.46 to 570.77Bq·kg-1 for 40K with the mean values of 42.11, 43.27, 9.5 and 418.27Bq·kg-1, respectively. The radium equivalent activity in all the soil samples is lower than the safe limit set in the OECD report (370Bq·kg-1). Man-made radionuclide 137Cs is also present in detectable amount in all soil samples. Presence of 137Cs indicates that the samples in this remote area also receive some fallout from nuclear accident in Chernobyl power plant in 1986. The internal and external hazard indices have the mean values of 0.48 and 0.37 respectively. Absorbed dose rates and effective dose equivalents are also determined for the samples. The concentration of radionuclides found in the soil samples during the present study is nominal and does not pose any potential health hazard to the general public.

  10. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Volotskova, O; Xu, A; Jozsef, G

    Purpose: To investigate the response and dose rate dependence of a scintillation detector over a wide energy range. Methods: The energy dependence of W1 scintillation detector was tested with: 1) 50–225 keV beams generated by an animal irradiator, 2) a Leksell Gamma Knife Perfexion Co-60 source, 3) 6MV, 6FFF, 10FFF and 15MV photon beams, and 4) 6–20MeV electron beams from a linac. Calibrated linac beams were used to deliver 100 cGy to the detector at dmax in water under reference conditions. The gamma-knife measurement was performed in solid water (100 cGy with 16mm collimator). The low energy beams were calibratedmore » with an ion chamber in air (TG-61), and the scintillation detector was placed at the same location as the ionization chamber during calibration. For the linac photon and electron beams, dose rate dependence was tested for 100–2400 and 100–800 MU/min. Results: The scintillation detector demonstrated strong energy dependence in the range of 50–225keV. The measured values were lower than the delivered dose and increased as the energy increased. Therapeutic photon beams showed energy independence with variations less than 1%. Therapeutic electron beams displayed the same sensitivity of ∼2–3% at their corresponding dmax depths. The change in dose-rate of photon and electron beams within the therapeutic energy range did not affect detector output (<0.5%). Measurements acquired with the gamma knife showed that the output data agreed with the delivered dose up to 3%. Conclusion: W1 scintillation detector output has a strong energy dependence in the diagnostic and orthovoltage energy range. Therapeutic photon beams exhibited energy independence with no observable dose-rate dependence. This study may aid in the implementation of a scintillation detector in QA programs by providing energy calibration factors.« less

  11. Mechanism of action for anti-radiation vaccine in reducing the biological impact of high-dose gamma irradiation

    NASA Astrophysics Data System (ADS)

    Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

    Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after high-dose gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naïve animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which they mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

  12. SU-F-T-619: Dose Evaluation of Specific Patient Plans Based On Monte Carlo Algorithm for a CyberKnife Stereotactic Radiosurgery System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Piao, J; PLA 302 Hospital, Beijing; Xu, S

    2016-06-15

    Purpose: This study will use Monte Carlo to simulate the Cyberknife system, and intend to develop the third-party tool to evaluate the dose verification of specific patient plans in TPS. Methods: By simulating the treatment head using the BEAMnrc and DOSXYZnrc software, the comparison between the calculated and measured data will be done to determine the beam parameters. The dose distribution calculated in the Raytracing, Monte Carlo algorithms of TPS (Multiplan Ver4.0.2) and in-house Monte Carlo simulation method for 30 patient plans, which included 10 head, lung and liver cases in each, were analyzed. The γ analysis with the combinedmore » 3mm/3% criteria would be introduced to quantitatively evaluate the difference of the accuracy between three algorithms. Results: More than 90% of the global error points were less than 2% for the comparison of the PDD and OAR curves after determining the mean energy and FWHM.The relative ideal Monte Carlo beam model had been established. Based on the quantitative evaluation of dose accuracy for three algorithms, the results of γ analysis shows that the passing rates (84.88±9.67% for head,98.83±1.05% for liver,98.26±1.87% for lung) of PTV in 30 plans between Monte Carlo simulation and TPS Monte Carlo algorithms were good. And the passing rates (95.93±3.12%,99.84±0.33% in each) of PTV in head and liver plans between Monte Carlo simulation and TPS Ray-tracing algorithms were also good. But the difference of DVHs in lung plans between Monte Carlo simulation and Ray-tracing algorithms was obvious, and the passing rate (51.263±38.964%) of γ criteria was not good. It is feasible that Monte Carlo simulation was used for verifying the dose distribution of patient plans. Conclusion: Monte Carlo simulation algorithm developed in the CyberKnife system of this study can be used as a reference tool for the third-party tool, which plays an important role in dose verification of patient plans. This work was supported in part by the

  13. Hematopoietic responses under protracted exposures to low daily dose gamma irradiation

    NASA Astrophysics Data System (ADS)

    Seed, T. M.; Fritz, T. E.; Tolle, D. V.; Jackson, W. E.

    In attempting to evaluate the possible health consequences of chronic ionizing radiation exposure during extended space travel (e.g., Mars Mission), ground-based experimental studies of the clinical and pathological responses of canines under low daily doses of 60Co gamma irradiation (0.3-26.3 cGy d -1) have been examined. Specific reference was given to responses of the blood forming system. Results suggest that the daily dose rate of 7.5 cGy d -1 represents a threshold below which the hematopoietic system can retain either partial or full trilineal cell-producing capacity (erythropoiesis, myelopoiesis, and megakaryopoiesis) for extended periods of exposure (> 1yr). Trilineal capacity was fully retained for several years of exposure at the lowest dose-rate tested (0.3 cGy d -1) but was completely lost within several hundred days at the highest dose-rate (26.3 cGy d -1). Retention of hematopoietic capacity under chronic exposure has been demonstrated to be mediated by hematopoietic progenitors with acquired radioresistance and repair functions, altered cytogenetics, and cell-cycle characteristics. Radiological, biological, and temporal parameters responsible for these vital acquisitions by hematopoietic progenitors have been partially characterized. These parameters, along with threshold responses, are described and discussed in relation to potential health risks of the space traveler under chronic stress of low-dose irradiation.

  14. Hematopoietic responses under protracted exposures to low daily dose gamma irradiation.

    PubMed

    Seed, T M; Fritz, T E; Tolle, D V; Jackson, W E

    2002-01-01

    In attempting to evaluate the possible health consequences of chronic ionizing radiation exposure during extended space travel (e.g., Mars Mission), ground-based experimental studies of the clinical and pathological responses of canines under low daily doses of 60Co gamma irradiation (0.3-26.3 cGy d-1) have been examined. Specific reference was given to responses of the blood forming system. Results suggest that the daily dose rate of 7.5 cGy d-1 represents a threshold below which the hematopoietic system can retain either partial or full trilineal cell-producing capacity (erythropoiesis, myelopoiesis, and megakaryopoiesis) for extended periods of exposure (>1 yr). Trilineal capacity was fully retained for several years of exposure at the lowest dose-rate tested (0.3 cGy d-1) but was completely lost within several hundred days at the highest dose-rate (26.3 cGy d-1). Retention of hematopoietic capacity under chronic exposure has been demonstrated to be mediated by hematopoietic progenitors with acquired radioresistance and repair functions, altered cytogenetics, and cell-cycle characteristics. Radiological, biological, and temporal parameters responsible for these vital acquisitions by hematopoietic progenitors have been partially characterized. These parameters, along with threshold responses, are described and discussed in relation to potential health risks of the space traveler under chronic stress of low-dose irradiation. Published by Elsevier Science Ltd on behalf of COSPAR.

  15. Splash M-knife versus Flush Knife BT in the technical outcomes of endoscopic submucosal dissection for early gastric cancer: a propensity score matching analysis.

    PubMed

    Esaki, Mitsuru; Suzuki, Sho; Hayashi, Yasuyo; Yokoyama, Azusa; Abe, Shuichi; Hosokawa, Taizo; Ogino, Haruei; Akiho, Hirotada; Ihara, Eikichi; Ogawa, Yoshihiro

    2018-02-27

    Endoscopic submucosal dissection (ESD) is a standard treatment for early gastric cancer. A new multi-functional ESD device was developed to achieve complete ESD with a single device. A metal plate attached to its distal sheath achieves better hemostasis during the procedure than the other needle-knife device, Flush Knife BT®, that has been conventionally used. The aim of this study was to compare the technical outcomes of ESD for early gastric cancer using the Splash M-Knife® with those using the Flush Knife BT. We conducted a retrospective review of the case records of 149 patients with early gastric cancer treated with ESD using the needle-type ESD knives between January 2012 and August 2016 at Kitakyushu Municipal Medical Center. Lesions treated with ESD using the Splash M-knife (ESD-M) and the Flush Knife BT (ESD-F) were compared. Multivariate analyses and propensity score matching were used to compensate for the differences in age, gender, underlying disease, antithrombotic drug use, lesion location, lesion position, macroscopic type, tumor size, presence of ulceration, operator level and types of electrosurgical unit used. The primary endpoint was the requirement to use hemostatic forceps in the two groups. The secondary endpoints of procedure time, en bloc and complete resection rates, and adverse events rates were evaluated for the two groups. There were 73 patients in the ESD-M group, and 76 patients in the ESD-F group. Propensity score matching analysis created 45 matched pairs. Adjusted comparisons between the two groups showed a significantly lower usage rate of hemostatic forceps in the ESD-M group than in the ESD-F group (6.7% vs 84.4%, p < 0.001). Treatment outcomes showed an en bloc resection rate of 100% in both groups; complete resection rate of 95.6% vs 100%, p = 0.49; median procedure time of 74.0 min vs 71.0 min, p = 0.90; post-procedure bleeding of 2.2% vs 2.2%, p = 1, in the ESD-M and ESD-F groups, respectively. There were

  16. Caffeine induces a second wave of apoptosis after low dose-rate gamma radiation of HL-60 cells.

    PubMed

    Vávrová, Jirina; Mareková-Rezácová, Martina; Vokurková, Doris; Szkanderová, Sylva; Psutka, Jan

    2003-10-01

    Most cell lines that lack functional p53 protein are arrested in the G(2) phase of the cell cycle due to DNA damage. It was previously found that the human promyelocyte leukemia cells HL-60 (TP53 negative) that had been exposed to ionizing radiation at doses up to 10 Gy were arrested in the G(2) phase for a period of 24 h. The radioresistance of HL-60 cells that were exposed to low dose-rate gamma irradiation of 3.9 mGy/min, which resulted in a pronounced accumulation of the cells in the G(2) phase during the exposure period, increased compared with the radioresistance of cells that were exposed to a high dose-rate gamma irradiation of 0.6 Gy/min. The D(0) value (i.e. the radiation dose leading to 37% cell survival) for low dose-rate radiation was 3.7 Gy and for high dose-rate radiation 2.2 Gy. In this study, prevention of G(2) phase arrest by caffeine (2 mM) and irradiation of cells with low dose-rate irradiation in all phases of the cell cycle proved to cause radiosensitization (D(0)=2.2 Gy). The irradiation in the presence of caffeine resulted in a second wave of apoptosis on days 5-7 post-irradiation. Caffeine-induced apoptosis occurring later than day 7 post-irradiation is postulated to be a result of unscheduled DNA replication and cell cycle progress.

  17. Dose estimation to eye lens of industrial gamma radiography workers using the Monte Carlo method.

    PubMed

    de Lima, Alexandre Roza; Hunt, John Graham; Da Silva, Francisco Cesar Augusto

    2017-12-01

    The ICRP Statement on Tissue Reactions (2011), based on epidemiological evidence, recommended a reduction for the eye lens equivalent dose limit from 150 to 20 mSv per year. This paper presents mainly the dose estimations received by industrial gamma radiography workers, during planned or accidental exposure to the eye lens, Hp(10) and effective dose. A Brazilian Visual Monte Carlo Dose Calculation program was used and two relevant scenarios were considered. For the planned exposure situation, twelve radiographic exposures per day for 250 days per year, which leads to a direct exposure of 10 h per year, were considered. The simulation was carried out using a 192 Ir source with 1.0 TBq of activity; a source/operator distance between 5 and 10 m and placed at heights of 0.02 m, 1 m and 2 m, and an exposure time of 12 s. Using a standard height of 1 m, the eye lens doses were estimated as being between 16.3 and 60.3 mGy per year. For the accidental exposure situation, the same radionuclide and activity were used, but in this case the doses were calculated with and without a collimator. The heights above ground considered were 1.0 m, 1.5 m and 2.0 m; the source/operator distance was 40 cm, and the exposure time 74 s. The eye lens doses at 1.5 m were 12.3 and 0.28 mGy without and with a collimator, respectively. The conclusions were that: (1) the estimated doses show that the 20 mSv annual limit for eye lens equivalent dose can directly impact industrial gamma radiography activities, mainly in industries with high number of radiographic exposures per year; (2) the risk of lens opacity has a low probability for a single accident, but depending on the number of accidental exposures and the dose levels found in planned exposures, the threshold dose can easily be exceeded during the professional career of an industrial radiography operator, and; (3) in a first approximation, Hp(10) can be used to estimate the equivalent dose to the eye lens.

  18. Increased Radioresistance to Lethal Doses of Gamma Rays in Mice and Rats after Exposure to Microwave Radiation Emitted by a GSM Mobile Phone Simulator

    PubMed Central

    Mortazavi, SMJ; Mosleh-Shirazi, MA; Tavassoli, AR; Taheri, M; Mehdizadeh, AR; Namazi, SAS; Jamali, A; Ghalandari, R; Bonyadi, S; Haghani, M; Shafie, M

    2013-01-01

    The aim of this study was to investigate the effect of pre-irradiation with microwaves on the induction of radioadaptive response. In the 1st phase of the study, 110 male mice were divided into 8 groups. The animals in these groups were exposed/sham-exposed to microwave, low dose rate gamma or both for 5 days. On day six, the animals were exposed to a lethal dose (LD). In the 2nd phase, 30 male rats were divided into 2 groups of 15 animals. The 1st group received microwave exposure. The 2nd group (controls) received the same LD but there was no treatment before the LD. On day 5, all animals were whole-body irradiated with the LD. Statistically significant differences between the survival rate of the mice only exposed to lethal dose of gamma radiation before irradiation with a lethal dose of gamma radiation with those of the animals pre-exposed to either microwave (p=0.02), low dose rate gamma (p=0.001) or both of these physical adapting doses (p=0.003) were observed. Likewise, a statistically significant difference between survival rates of the rats in control and test groups was observed. Altogether, these experiments showed that exposure to microwave radiation may induce a significant survival adaptive response. PMID:23930107

  19. Cytogenetic Reconstruction of Gamma-Ray Doses Delivered to Atomic Bomb Survivors: Dealing with Wide Distributions of Photon Energies and Contributions from Hematopoietic Stem/Progenitor Cells.

    PubMed

    Nakamura, Nori; Hirai, Yuko; Kodama, Yoshiaki; Hamasaki, Kanya; Cullings, Harry M; Cordova, Kismet A; Awa, Akio

    2017-10-01

    Retrospective estimation of the doses received by atomic bomb (A-bomb) survivors by cytogenetic methods has been hindered by two factors: One is that the photon energies released from the bomb were widely distributed, and since the aberration yield varies depending on the energy, the use of monoenergetic 60 Co gamma radiation to construct a calibration curve may bias the estimate. The second problem is the increasing proportion of newly formed lymphocytes entering into the lymphocyte pool with increasing time intervals since the exposures. These new cells are derived from irradiated precursor/stem cells whose radiosensitivity may differ from that of blood lymphocytes. To overcome these problems, radiation doses to tooth enamel were estimated using the electron spin resonance (ESR; or EPR, electron paramagnetic resonance) method and compared with the cytogenetically estimated doses from the same survivors. The ESR method is only weakly dependent on the photon energy and independent of the years elapsed since an exposure. Both ESR and cytogenetic doses were estimated from 107 survivors. The latter estimates were made by assuming that although a part of the cells examined could be lymphoid stem or precursor cells at the time of exposure, all the cells had the same radiosensitivity as blood lymphocytes, and that the A-bomb gamma-ray spectrum was the same as that of the 60 Co gamma rays. Subsequently, ESR and cytogenetic endpoints were used to estimate the kerma doses using individual DS02R1 information on shielding conditions. The results showed that the two sets of kerma doses were in close agreement, indicating that perhaps no correction is needed in estimating atomic bomb gamma-ray doses from the cytogenetically estimated 60 Co gamma-ray equivalent doses. The present results will make it possible to directly compare cytogenetic doses with the physically estimated doses of the survivors, which would pave the way for testing whether or not there are any systematic

  20. Calculations of the skyshine gamma-ray dose rates from independent spent fuel storage installations (ISFSI) under worst case accident conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pace, J.V. III; Cramer, S.N.; Knight, J.R.

    1980-09-01

    Calculations of the skyshine gamma-ray dose rates from three spent fuel storage pools under worst case accident conditions have been made using the discrete ordinates code DOT-IV and the Monte Carlo code MORSE and have been compared to those of two previous methods. The DNA 37N-21G group cross-section library was utilized in the calculations, together with the Claiborne-Trubey gamma-ray dose factors taken from the same library. Plots of all results are presented. It was found that the dose was a strong function of the iron thickness over the fuel assemblies, the initial angular distribution of the emitted radiation, and themore » photon source near the top of the assemblies. 16 refs., 11 figs., 7 tabs.« less

  1. A cross-sectional study of knife injuries at a London major trauma centre

    PubMed Central

    Sutherland, E; Glucksman, E; Tunnicliff, M; Keep, JW

    2014-01-01

    INTRODUCTION No national recording systems for knife injuries exist in the UK. Understanding the true size and nature of the problem of knife injuries is the first stage in reducing the burden of this injury. The aim of this study was to survey every knife injury seen in a single inner city emergency department (ED) over a one-year period. METHODS A cross-sectional observational study was performed of all patients attending with a knife injury to the ED of a London major trauma centre in 2011. Demographic characteristics, patterns of injury, morbidity and mortality data were collected. RESULTS A total of 938 knife injuries were identified from 127,191 attendances (0.77% of all visits) with a case fatality rate of 0.53%. A quarter (24%) of the major trauma team’s caseload was for knife injuries. Overall, 44% of injuries were selfreported as assaults, 49% as accidents and 8% as deliberate self-harm. The highest age specific incident rate occurred in the 16–24 year age category (263/100,000). Multiple injuries were seen in 19% of cases, of which only 81% were recorded as assaults. The mean length of stay for those admitted to hospital was 3.04 days. Intrathoracic injury was seen in 26% of cases of chest trauma and 24% of abdominal injuries had a second additional chest injury. CONCLUSIONS Violent intentional injuries are a significant contributory factor to the workload of the major trauma team at this centre. This paper contributes to a more comprehensive understanding of the nature of these injuries seen in the ED. PMID:24417825

  2. The Use of Cone Beam Computed Tomography for Image Guided Gamma Knife Stereotactic Radiosurgery: Initial Clinical Evaluation.

    PubMed

    Li, Winnie; Cho, Young-Bin; Ansell, Steve; Laperriere, Normand; Ménard, Cynthia; Millar, Barbara-Ann; Zadeh, Gelareh; Kongkham, Paul; Bernstein, Mark; Jaffray, David A; Chung, Caroline

    2016-09-01

    The present study used cone beam computed tomography (CBCT) to measure the inter- and intrafraction uncertainties for intracranial stereotactic radiosurgery (SRS) using the Leksell Gamma Knife (GK). Using a novel CBCT system adapted to the GK radiosurgery treatment unit, CBCT images were acquired immediately before and after treatment for each treatment session within the context of a research ethics board-approved prospective clinical trial. Patients were immobilized in the Leksell coordinate frame (LCF) for both volumetric CBCT imaging and GK-SRS delivery. The relative displacement of the patient's skull to the stereotactic reference (interfraction motion) was measured for each CBCT scan. Differences between the pre- and post-treatment CBCT scans were used to determine the intrafraction motion. We analyzed 20 pre- and 17 post-treatment CBCT scans in 20 LCF patients treated with SRS. The mean translational pretreatment setup error ± standard deviation in the left-right, anteroposterior, and craniocaudal directions was -0.19 ± 0.32, 0.06 ± 0.27, and -0.23 ± 0.2 mm, with a maximum of -0.74, -0.53, and -0.68 mm, respectively. After an average time between the pre- and post-treatment CBCT scans of 82 minutes (range 27-170), the mean intrafraction error ± standard deviation for the LCF was -0.03 ± 0.05, -0.03 ± 0.18, and -0.03 ± 0.12 mm in the left-right, anteroposterior, and craniocaudual direction, respectively. Using CBCT on a prototype image guided GK Perfexion unit, we were able to measure the inter- and intrafraction positional changes for GK-SRS using the invasive frame. In the era of image guided radiation therapy, the use of CBCT image guidance for both frame- and non-frame-based immobilization systems could serve as a useful quality assurance tool. Our preliminary measurements can guide the application of achievable thresholds for inter- and intrafraction discrepancy when moving to a frameless approach. Copyright © 2016 The Authors

  3. Usefulness of the advanced neuroimaging protocol based on plain and gadolinium-enhanced constructive interference in steady state images for gamma knife radiosurgery and planning microsurgical procedures for skull base tumors.

    PubMed

    Hayashi, Motohiro; Chernov, Mikhail F; Tamura, Noriko; Yomo, Shoji; Tamura, Manabu; Horiba, Ayako; Izawa, Masahiro; Muragaki, Yoshihiro; Iseki, Hiroshi; Okada, Yoshikazu; Ivanov, Pavel; Régis, Jean; Takakura, Kintomo

    2013-01-01

    Gamma Knife radiosurgery (GKS) is currently performed with 0.1 mm preciseness, which can be designated microradiosurgery. It requires advanced methods for visualizing the target, which can be effectively attained by a neuroimaging protocol based on plain and gadolinium-enhanced constructive interference in steady state (CISS) images. Since 2003, the following thin-sliced images are routinely obtained before GKS of skull base lesions in our practice: axial CISS, gadolinium-enhanced axial CISS, gadolinium-enhanced axial modified time-of-flight (TOF), and axial computed tomography (CT). Fusion of "bone window" CT and magnetic resonance imaging (MRI), and detailed three-dimensional (3D) delineation of the anatomical structures are performed with the Leksell GammaPlan (Elekta Instruments AB). Recently, a similar technique has been also applied to evaluate neuroanatomy before open microsurgical procedures. Plain CISS images permit clear visualization of the cranial nerves in the subarachnoid space. Gadolinium-enhanced CISS images make the tumor "lucid" but do not affect the signal intensity of the cranial nerves, so they can be clearly delineated in the vicinity to the lesion. Gadolinium-enhanced TOF images are useful for 3D evaluation of the interrelations between the neoplasm and adjacent vessels. Fusion of "bone window" CT and MRI scans permits simultaneous assessment of both soft tissue and bone structures and allows 3D estimation and correction of MRI distortion artifacts. Detailed understanding of the neuroanatomy based on application of the advanced neuroimaging protocol permits performance of highly conformal and selective radiosurgical treatment. It also allows precise planning of the microsurgical procedures for skull base tumors.

  4. Very low dose gamma irradiation stimulates gaseous exchange and carboxylation efficiency, but inhibits vascular sap flow in groundnut (Arachis hypogaea L.).

    PubMed

    Ahuja, Sumedha; Singh, Bhupinder; Gupta, Vijay Kumar; Singhal, R K; Venu Babu, P

    2014-02-01

    An experiment was carried out to determine the effect of low dose gamma radiation on germination, plant growth, nitrogen and carbon fixation and carbon flow and release characteristics of groundnut. Dry seeds of groundnut variety Trombay groundnut 37A (TG 37A), a radio mutant type developed by Bhabha Atomic Research Centre (BARC), Mumbai, India, were subjected to the pre-sowing treatment of gamma radiation within low to high dose physiological range, i.e., 0.0, 0.0082, 0.0164. 0.0328, 0.0656, 0.1312, 5, 25, 100, 500 Gray (Gy) from a cobalt source ((60)Co). Observations were recorded for the radiation effect on percentage germination, vigour, gas exchange attributes such as photosynthetic rate, stomatal conductance and transpiration rate, chlorophyll content, root exudation in terms of (14)C release, vascular sap flow rate and activities of rate defining carbon and nitrogen assimilating enzymes such as ribulose-1,5-bisphosphate carboxylase (rubisco) and nitrate reductase (NR). Seed germination was increased by 10-25% at the lower doses up to 5 Gy while the improvement in plant vigour in the same dose range was much higher (22-84%) than the unirradiated control. For radiation exposure above 5 Gy, a dose-dependent decline in germination and plant vigour was measured. No significant effect was observed on the photosynthesis at radiation exposure below 5 Gy but above 5 Gy dose there was a decline in the photosynthetic rate. Stomatal conductance and transpiration rate, however, were only inhibited at a high dose of 500 Gy. Leaf rubisco activity and NR activities remained unaffected at all the investigated doses of gamma irradiation. Mean root exudation and sap flow rate of the irradiated plants, irrespective of the dose, was reduced over the unirradiated control more so in a dose-dependent manner. Results indicated that a very low dose of gamma radiation, in centigray to gray range, did not pose any threat and in fact stimulated metabolic functions in such a way to aid

  5. A continuous arc delivery optimization algorithm for CyberKnife m6.

    PubMed

    Kearney, Vasant; Descovich, Martina; Sudhyadhom, Atchar; Cheung, Joey P; McGuinness, Christopher; Solberg, Timothy D

    2018-06-01

    This study aims to reduce the delivery time of CyberKnife m6 treatments by allowing for noncoplanar continuous arc delivery. To achieve this, a novel noncoplanar continuous arc delivery optimization algorithm was developed for the CyberKnife m6 treatment system (CyberArc-m6). CyberArc-m6 uses a five-step overarching strategy, in which an initial set of beam geometries is determined, the robotic delivery path is calculated, direct aperture optimization is conducted, intermediate MLC configurations are extracted, and the final beam weights are computed for the continuous arc radiation source model. This algorithm was implemented on five prostate and three brain patients, previously planned using a conventional step-and-shoot CyberKnife m6 delivery technique. The dosimetric quality of the CyberArc-m6 plans was assessed using locally confined mutual information (LCMI), conformity index (CI), heterogeneity index (HI), and a variety of common clinical dosimetric objectives. Using conservative optimization tuning parameters, CyberArc-m6 plans were able to achieve an average CI difference of 0.036 ± 0.025, an average HI difference of 0.046 ± 0.038, and an average LCMI of 0.920 ± 0.030 compared with the original CyberKnife m6 plans. Including a 5 s per minute image alignment time and a 5-min setup time, conservative CyberArc-m6 plans achieved an average treatment delivery speed up of 1.545x ± 0.305x compared with step-and-shoot plans. The CyberArc-m6 algorithm was able to achieve dosimetrically similar plans compared to their step-and-shoot CyberKnife m6 counterparts, while simultaneously reducing treatment delivery times. © 2018 American Association of Physicists in Medicine.

  6. Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carl, W. F.

    NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

  7. A new strategy of CyberKnife treatment system based radiosurgery followed by early use of adjuvant bevacizumab treatment for brain metastasis with extensive cerebral edema.

    PubMed

    Wang, Yang; Wang, Enmin; Pan, Li; Dai, Jiazhong; Zhang, Nan; Wang, Xin; Liu, Xiaoxia; Mei, Guanghai; Sheng, Xiaofang

    2014-09-01

    Bevacizumab blocks the effects of vascular endothelial growth factor in leakage-prone capillaries and has been suggested as a new treatment for cerebral radiation edema and necrosis. CyberKnife is a new, frameless stereotactic radiosurgery system. This work investigated the safety and efficacy of CyberKnife followed by early bevacizumab treatment for brain metastasis with extensive cerebral edema. The eligibility criteria of the patients selected for radiosurgery followed by early use of adjuvant bevacizumab treatment were: (1) brain tumors from metastasis with one solitary brain lesion and symptomatic extensive cerebral edema; (2) >18 years of age; (3) the patient refused surgery due to the physical conditions and the risk of surgery; (4) no contraindications for bevacizumab. (5) bevacizumab was applied for a minimum of 2 injections and a maximum of 6 injections with a 2-week interval between treatments, beginning within 2 weeks of the CyberKnife therapy; (6) Karnofsky performance status (KPS) ≥30. Tumor size and edema were monitored by magnetic resonance imaging (MRI). Dexamethasone dosage, KPS, adverse event occurrence and associated clinical outcomes were also recorded. Eight patients were accrued for this new treatment. Radiation dose ranged from 20 to 33 Gy in one to five sessions, prescribed to the 61-71 % isodose line. Bevacizumab therapy was administered 3-10 days after completion of CyberKnife treatment for a minimum of two cycles (5 mg/kg, at 2-week intervals). MRI revealed average reductions of 55.8 % (post-gadolinium) and 63.4 % (T2/FLAIR). Seven patients showed significant clinical neurological improvements. Dexamethasone was reduced in all patients, with five successfully discontinuing dexamethasone treatment 4 weeks after bevacizumab initiation. Hypertension, a bevacizumab-related adverse event, occurred in one patient. After 3-8 months, all patients studied were alive and primary brain metastases were under control, 2 developed new brain

  8. Scissor-type knife significantly improves self-completion rate of colorectal endoscopic submucosal dissection: Single-center prospective randomized trial.

    PubMed

    Yamashina, Takeshi; Takeuchi, Yoji; Nagai, Kengo; Matsuura, Noriko; Ito, Takashi; Fujii, Mototsugu; Hanaoka, Noboru; Higashino, Koji; Uedo, Noriya; Ishihara, Ryu; Iishi, Hiroyasu

    2017-05-01

    Colorectal endoscopic submucosal dissection (C-ESD) is recognized as a difficult procedure. Recently, scissors-type knives were launched to reduce the difficulty of C-ESD. The aim of this study was to evaluate the efficacy and safety of the combined use of a scissors-type knife and a needle-type knife with a water-jet function (WJ needle-knife) for C-ESD compared with using the WJ needle-knife alone. This was a prospective randomized controlled trial in a referral center. Eighty-five patients with superficial colorectal neoplasms were enrolled and randomly assigned to undergo C-ESD using a WJ needle-knife alone (Flush group) or a scissor-type knife-supported WJ needle-knife (SB Jr group). Procedures were conducted by two supervised residents. Primary endpoint was self-completion rate by the residents. Self-completion rate was 67% in the SB Jr group, which was significantly higher than that in the Flush group (39%, P = 0.01). Even after exclusion of four patients in the SB Jr group in whom C-ESD was completed using the WJ needle-knife alone, the self-completion rate was significantly higher (63% vs 39%; P = 0.03). Median procedure time among the self-completion cases did not differ significantly between the two groups (59 vs 51 min; P = 0.14). No fatal adverse events were observed in either group. In this single-center phase II trial, scissor-type knife significantly improved residents' self-completion rate for C-ESD, with no increase in procedure time or adverse events. A multicenter trial would be warranted to confirm the validity of the present study. © 2016 Japan Gastroenterological Endoscopy Society.

  9. Microbial decontamination by low dose gamma irradiation and its impact on the physico-chemical quality of peppermint (Mentha piperita)

    NASA Astrophysics Data System (ADS)

    Machhour, Hasna; El Hadrami, Ismail; Imziln, Boujamaa; Mouhib, Mohamed; Mahrouz, Mostafa

    2011-04-01

    Peppermint was inoculated with Escherichia coli and its decontamination was carried out by gamma irradiation at low irradiation doses (0.5, 1.0 and 2.66 kGy). The efficiency of this decontamination method was evaluated and its impact on the quality parameters of peppermint, such as the color and ash content, as well as the effect on fingerprint components such as phenols and essential oils, was studied. Gas chromatography coupled to mass spectrometry (GC/MS) and High Performance Liquid Chromatography (HPLC) were used to characterize essential oils and phenolic compounds, respectively. The results indicated a complete decontamination of peppermint after the low dose gamma irradiation without a significant loss in quality attributes.

  10. Two-dimensional straightness measurement based on optical knife-edge sensing

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Zhong, Fenghe; Ellis, Jonathan D.

    2017-09-01

    Straightness error is a parasitic translation along a perpendicular direction to the primary displacement axis of a linear stage. The parasitic translations could be coupled into other primary displacement directions of a multi-axis platform. Hence, its measurement and compensation are critical in precision multi-axis metrology, calibration, and manufacturing. This paper presents a two-dimensional (2D) straightness measurement configuration based on 2D optical knife-edge sensing, which is simple, light-weight, compact, and easy to align. It applies a 2D optical knife-edge to manipulate the diffraction pattern sensed by a quadrant photodetector, whose output voltages could derive 2D straightness errors after a calibration process. This paper analyzes the physical model of the configuration and performs simulations and experiments to study the system sensitivity, measurement nonlinearity, and error sources. The results demonstrate that the proposed configuration has higher sensitivity and insensitive to beam's vibration, compared with the conventional configurations without using the knife-edge, and could achieve ±0.25 μ m within a ±40 μ m measurement range along a 40 mm primary axial motion.

  11. Neutron and gamma-ray dose measurements at various distances from the Little Boy replica

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huntzinger, C.J.; Hankins, D.E.

    We measured neutron and gamma-ray dose rates at various distances from the Little Boy-Comet Critical Assembly at Los Alamos National Laboratory (LANL) in April of 1983. The Little Boy-Comet Assembly is a replica of the atomic weapon detonated over Hiroshima, designed to be operated at various steady-state power levels. The selected distances for measurement ranged from 107 m to 567 m. Gamma-ray measurements were made with a Reuter-Stokes environmental ionization chamber which has a sensitivity of 1.0 ..mu..R/hour. Neutron measurements were made with a pulsed-source remmeter which has a sensitivity of 0.1 ..mu..rem/hour, designed and built at Lawrence Livermore Nationalmore » Laboratory (LLNL). 12 references, 7 figures, 6 tables.« less

  12. Evaluation of the Environmental Gamma-ray Dose Rate by Skyshine Analysis During the Maintenance of an Activated TFC in ITER

    NASA Astrophysics Data System (ADS)

    Sato, S.; Takatsu, H.; Maki, K.; Yamada, K.; Mori, S.; Iida, H.; Santoro, R. T.

    1997-09-01

    Gamma-ray exposure dose rates at the ITER site boundary were estimated for the cases of removal of a failed activated Toroidal Field (TF) coil from the torus and removal of a failed activated TF coil together with a sector of the activated Vacuum Vessel (VV). Skyshine analyses were performed using the two-dimensional SN radiation transport code, DOT3.5. The exposure gamma-ray dose rates on the ground at the site boundary (presently assumed to be 1 km from the ITER building), were calculated to be 1.1 and 84 μSv/year for removal of the TF coil without and with a VV sector, respectively. The dose rate level for the latter case is close to the tentative radiation limit of 100 μSv/year so an additional ˜14 cm of concrete is required in the ITER building roof to satisfy the criterion for a safety factor often for the site boundary dose rate.

  13. The value of image coregistration during stereotactic radiosurgery.

    PubMed

    Koga, T; Maruyama, K; Igaki, H; Tago, M; Saito, N

    2009-05-01

    Coregistration of any neuroimaging studies into treatment planning for stereotactic radiosurgery became easily applicable using the Leksell Gamma Knife 4C, a new model of gamma knife. The authors investigated the advantage of this image processing. Since installation of the Leksell Gamma Knife 4C at the authors' institute, 180 sessions of radiosurgery were performed. Before completion of planning, coregistration of frameless images of other modalities or previous images was considered to refine planning. Treatment parameters were compared for planning before and after refinement by use of coregistered images. Coregistered computed tomography clarified the anatomical structures indistinct on magnetic resonance imaging. Positron emission tomography visualized lesions disclosing metabolically high activity. Coregistration of prior imaging distinguished progressing lesions from stable ones. Diffusion-tensor tractography was integrated for lesions adjacent to the corticospinal tract or the optic radiation. After refinement of planning in 36 sessions, excess treated volume decreased (p = 0.0062) and Paddick conformity index improved (p < 0.001). Maximal dose to the white matter tracts was decreased (p < 0.001). Image coregistration provided direct information on anatomy, metabolic activity, chronological changes, and adjacent critical structures. This gathered information was sufficiently informative during treatment planning to supplement ambiguous information on stereotactic images, and was useful especially in reducing irradiation to surrounding normal structures.

  14. A STUDY OF IMMUNOGENIC AND ANTIGENIC PROPERTIES OF DIPHTHERIA TOXOID EXPOSED TO STERILIZING DOSES OF $gamma$-RAYS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kaulen, D.R.

    1959-01-01

    Experimental results indicate that crude diphtheria toxoid may be exposed to sterilizing doses of gamma radiation without damage of its properties. Exposure of purified and adsorbed preparations resulted in a deterioration of immunogenic and antigenic properties of diphtheria toxoid. (C.H.)

  15. Lymphoid cell kinetics under continuous low dose-rate gamma irradiation: A comparison study

    NASA Technical Reports Server (NTRS)

    Foster, B. R.

    1975-01-01

    A comparison study was conducted of the effects of continuous low dose-rate gamma irradiation on cell population kinetics of lymphoid tissue (white pulp) of the mouse spleen with findings as they relate to the mouse thymus. Experimental techniques employed included autoradiography and specific labeling with tritiated thymidine (TdR-(h-3)). The problem studied involved the mechanism of cell proliferation of lymphoid tissue of the mouse spleen and thymus under the stress of continuous irradiation at a dose rate of 10 roentgens (R) per day for 105 days (15 weeks). The aim was to determine whether or not a steady state or near-steady state of cell population could be established for this period of time, and what compensatory mechanisms of cell population were involved.

  16. Blurred image restoration using knife-edge function and optimal window Wiener filtering.

    PubMed

    Wang, Min; Zhou, Shudao; Yan, Wei

    2018-01-01

    Motion blur in images is usually modeled as the convolution of a point spread function (PSF) and the original image represented as pixel intensities. The knife-edge function can be used to model various types of motion-blurs, and hence it allows for the construction of a PSF and accurate estimation of the degradation function without knowledge of the specific degradation model. This paper addresses the problem of image restoration using a knife-edge function and optimal window Wiener filtering. In the proposed method, we first calculate the motion-blur parameters and construct the optimal window. Then, we use the detected knife-edge function to obtain the system degradation function. Finally, we perform Wiener filtering to obtain the restored image. Experiments show that the restored image has improved resolution and contrast parameters with clear details and no discernible ringing effects.

  17. Blurred image restoration using knife-edge function and optimal window Wiener filtering

    PubMed Central

    Zhou, Shudao; Yan, Wei

    2018-01-01

    Motion blur in images is usually modeled as the convolution of a point spread function (PSF) and the original image represented as pixel intensities. The knife-edge function can be used to model various types of motion-blurs, and hence it allows for the construction of a PSF and accurate estimation of the degradation function without knowledge of the specific degradation model. This paper addresses the problem of image restoration using a knife-edge function and optimal window Wiener filtering. In the proposed method, we first calculate the motion-blur parameters and construct the optimal window. Then, we use the detected knife-edge function to obtain the system degradation function. Finally, we perform Wiener filtering to obtain the restored image. Experiments show that the restored image has improved resolution and contrast parameters with clear details and no discernible ringing effects. PMID:29377950

  18. Preliminary Results of Indoor Radon/thoron Concentrations and Terrestrial Gamma Doses in Gejiu, Yunnan, China

    NASA Astrophysics Data System (ADS)

    Ishikawa, Tetsuo; Tokonami, Shinji; Sun, Quafu; Kobayashi, Yosuke; Min, Xiangdong; Yoshinaga, Shinji

    2008-08-01

    A preliminary survey on indoor radon/thoron and external gamma ray dose rate was conducted for houses in Gejiu city and its neighboring village in Yunnan Province, China. As a result of the radon/thoron measurements for about 50 houses, very high thoron concentrations were found in some hoses (maximum: 7,900 Bq/m3). The mean annual dose from thoron decay products was estimated to be larger than that from radon decay products (2.9 mSv vs. 1.6 mSv). Further dosimetric and epidemiological studies are needed to investigate the possible effects of radon and thoron.

  19. Mechanism of Action for Anti-radiation Vaccine in Reducing the Biological Impact of High-dose Gamma Irradiation

    NASA Technical Reports Server (NTRS)

    Maliev, Vladislav; Popov, Dmitri; Jones, Jeffrey A.; Casey, Rachael C.

    2007-01-01

    Ionizing radiation is a major health risk of long-term space travel, the biological consequences of which include genetic and oxidative damage. In this study, we propose an original mechanism by which high doses of ionizing radiation induce acute toxicity. We identified biological components that appear in the lymphatic vessels shortly after gamma irradiation. These radiation-induced toxins, which we have named specific radiation determinants (SRD), were generated in the irradiated tissues and then collected and circulated throughout the body via the lymph circulation and bloodstream. Depending on the type of SRD elicited, different syndromes of acute radiation sickness (ARS) were expressed. The SRDs were developed into a vaccine used to confer active immunity against acute radiation toxicity in immunologically naive animals. Animals that were pretreated with SRDs exhibited resistance to lethal doses of gamma radiation, as measured by increased survival times and survival rates. In comparison, untreated animals that were exposed to similar large doses of gamma radiation developed acute radiation sickness and died within days. This phenomenon was observed in a number of mammalian species. Initial analysis of the biochemical characteristics indicated that the SRDs were large molecular weight (200-250 kDa) molecules that were comprised of a mixture of protein, lipid, carbohydrate, and mineral. Further analysis is required to further identify the SRD molecules and the biological mechanism by which the mediate the toxicity associated with acute radiation sickness. By doing so, we may develop an effective specific immunoprophylaxis as a countermeasure against the acute effects of ionizing radiation.

  20. Dose mapping inside a gamma irradiator measured with doped silica fibre dosimetry and Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Moradi, F.; Khandaker, M. U.; Mahdiraji, G. A.; Ung, N. M.; Bradley, D. A.

    2017-11-01

    In recent years doped silica fibre thermoluminescent dosimeters (TLD) have been demonstrated to have considerable potential for irradiation applications, benefitting from the available sensitivity, spatial resolution and dynamic dose range, with primary focus being on the needs of medical dosimetry. Present study concerns the dose distribution inside a cylindrically shaped gamma-ray irradiator cavity, with irradiator facilities such as the familiar 60Co versions being popularly used in industrial applications. Quality assurance of the radiation dose distribution inside the irradiation cell of such a device is of central importance in respect of the delivered dose to the irradiated material. Silica fibre TLD dose-rates obtained within a Gammacell-220 irradiator cavity show the existence of non-negligible dose distribution heterogeneity, by up to 20% and 26% in the radial and axial directions respectively, Monte Carlo simulations and available literature providing some support for present findings. In practice, it is evident that there is need to consider making corrections to nominal dose-rates in order to avoid the potential for under-dosing.

  1. Neutron-gamma flux and dose calculations for feasibility study of DISCOMS instrumentation in case of severe accident in a GEN 3 reactor

    NASA Astrophysics Data System (ADS)

    Brovchenko, Mariya; Duhamel, Isabelle; Dechenaux, Benjamin

    2017-09-01

    The present paper presents the study carried out in the frame of the DISCOMS project, which stands for "DIstributed Sensing for COrium Monitoring and Safety". This study concerns the calculation of the neutron and gamma radiations received by the considered instrumentation during the normal reactor operation as well as in case of a severe accident for the EPR reactor, outside the reactor pressure vessel and in the containment basemat. This paper summarizes the methods and hypotheses used for the particle transport simulation outside the vessel during normal reactor operation. The results of the simulations are then presented including the responses for distributed Optical Fiber Sensors (OFS), such as the gamma dose and the fast neutron fluence, and for Self Powered Neutron Detectors (SPNDs), namely the neutron and gamma spectra. Same responses are also evaluated for severe accident situations in order to design the SPNDs being sensitive to the both types of received neutron-gamma radiation. By contrast, fibers, involved as transducers in distributed OFS have to resist to the total radiation gamma dose and neutron fluence received during normal operation and the severe accident.

  2. Peroral Endoscopic Myotomy in Children: First Experience With a New Triangular Knife.

    PubMed

    Nabi, Zaheer; Ramchandani, Mohan; Chavan, Radhika; Tandan, Manu; Kalapala, Rakesh; Darisetty, Santosh; Reddy, Duvuur Nageshwar

    2018-01-01

    Peroral endoscopic myotomy (POEM) is a novel treatment modality for achalasia cardia. The procedure is technically challenging and time consuming. Recently, a new triangle tip knife (TTJ) has been introduced, which is equipped with water jet facility. In the present study, we analyzed the feasibility, safety, and efficacy of POEM in children with new triangle tip knife. We retrospectively evaluated the data of children (18 years or younger) who underwent POEM using TTJ knife at our institution. All POEM procedures were performed under general anesthesia in an endoscopy suite. Technical feasibility, safety, efficacy, and procedure duration were assessed. Ten children (4 boys, 6 girls) with mean age of 14.2 ± 2.74 (9-18) years, underwent POEM with TTJ knife. The subtypes of achalasia cardia were type I (4), type II (5), and type III (1). Two children had prior treatment with pneumatic balloon dilatation. POEM was performed via anterior route in majority of children (70%). Mean operating time was 47.6 ± 19.74 (30-98) minutes with no significant difference between anterior and posterior approaches to POEM (48.57 ± 24.01 vs 45.3 ± 3.51; P < 0.05). Four gas-related adverse events were encountered including capnoperitoneum and retroperitoneal carbon dioxide in 2 children each. Clinical success was noticed in 9 children with significant reduction in Eckardt score at 1 month after POEM (6.7 ± 1.49 vs 0.3 ± 0.48; P = 0.0001). POEM can be efficiently performed with new triangle knife equipped with water jet technique. Integration of water jet reduces procedure duration and technical difficulty with POEM.

  3. Esophageal Dose Tolerance in Patients Treated With Stereotactic Body Radiation Therapy.

    PubMed

    Nuyttens, Joost J; Moiseenko, Vitali; McLaughlin, Mark; Jain, Sheena; Herbert, Scott; Grimm, Jimm

    2016-04-01

    Mediastinal critical structures such as trachea, bronchus, esophagus, and heart are among the dose-limiting factors for stereotactic body radiation therapy (SBRT) to central lung lesions. The purpose of this study was to characterize the risk of esophagitis for patients treated with SBRT and to develop a statistical dose-response model to assess the equivalent uniform dose, D10%, D5cc, D1cc, and Dmax, to the esophagus and the risk of toxicity. Toxicity outcomes of a dose-escalation study of 56 patients who had taken CyberKnife treatment from 45-60Gy in 3-7 fractions at the Erasmus MC-Daniel den Hoed Cancer Center were utilized to create the dose-response model for esophagus. A total of 5 grade 2 esophageal complications were reported (Common Terminology Criteria for Adverse Events version 3.0); 4 complications were early effects and 1 complication was a late effect. All analyses were performed in terms of 5-fraction equivalent dosing. According to our study, D1cc at a dose of 32.9Gy and Dmax dose of 43.4Gy corresponded to a complication probability of 50% for grade 2 toxicity. In this series of 58 CyberKnife mediastinal lung cases, no grade 3 or higher esophageal toxicity occurred. Our estimates of esophageal toxicity are compared with the data in the literature. Further research needs to be performed to establish more reliable dose limits as longer follow-up and toxicity outcomes are reported in patients treated with SBRT for central lung lesions. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Analytical dose evaluation of neutron and secondary gamma-ray skyshine from nuclear facilities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hayashi, K.; Nakamura, T.

    1985-11-01

    The skyshine dose distributions of neutron and secondary gamma rays were calculated systematically using the Monte Carlo method for distances up to 2 km from the source. The energy of source neutrons ranged from thermal to 400 MeV; their emission angle from 0 to 90 deg from the ver tical was treated with a distribution of the direction cosine containing five equal intervals. Calculated dose distributions D(r) were fitted to the formula; D(r) = Q exp (-r/lambda)/r. The value of Q and lambda are slowly varied functions of energy. This formula was applied to the benchmark problems of neutron skyshinemore » from fission, fusion, and accelerator facilities, and good agreement was achieved. This formula will be quite useful for shielding designs of various nuclear facilities.« less

  5. Inverse modelling of radionuclide release rates using gamma dose rate observations

    NASA Astrophysics Data System (ADS)

    Hamburger, Thomas; Evangeliou, Nikolaos; Stohl, Andreas; von Haustein, Christoph; Thummerer, Severin; Wallner, Christian

    2015-04-01

    Severe accidents in nuclear power plants such as the historical accident in Chernobyl 1986 or the more recent disaster in the Fukushima Dai-ichi nuclear power plant in 2011 have drastic impacts on the population and environment. Observations and dispersion modelling of the released radionuclides help to assess the regional impact of such nuclear accidents. Modelling the increase of regional radionuclide activity concentrations, which results from nuclear accidents, underlies a multiplicity of uncertainties. One of the most significant uncertainties is the estimation of the source term. That is, the time dependent quantification of the released spectrum of radionuclides during the course of the nuclear accident. The quantification of the source term may either remain uncertain (e.g. Chernobyl, Devell et al., 1995) or rely on estimates given by the operators of the nuclear power plant. Precise measurements are mostly missing due to practical limitations during the accident. The release rates of radionuclides at the accident site can be estimated using inverse modelling (Davoine and Bocquet, 2007). The accuracy of the method depends amongst others on the availability, reliability and the resolution in time and space of the used observations. Radionuclide activity concentrations are observed on a relatively sparse grid and the temporal resolution of available data may be low within the order of hours or a day. Gamma dose rates, on the other hand, are observed routinely on a much denser grid and higher temporal resolution and provide therefore a wider basis for inverse modelling (Saunier et al., 2013). We present a new inversion approach, which combines an atmospheric dispersion model and observations of radionuclide activity concentrations and gamma dose rates to obtain the source term of radionuclides. We use the Lagrangian particle dispersion model FLEXPART (Stohl et al., 1998; Stohl et al., 2005) to model the atmospheric transport of the released radionuclides. The

  6. How Sharp Does a "Knife Edge" Have to Be?

    ERIC Educational Resources Information Center

    Dietz, Eric R.; Gash, Philip W.

    1994-01-01

    Describes an experiment designed to help understand the effect of the curvature of the laboratory equipment support (cylindrical rod instead of knife-edge) on the frequency of oscillation of pendula. (ZWH)

  7. mBAND analysis of chromosome aberrations in human epithelial cells induced by gamma-rays and secondary neutrons of low dose rate.

    PubMed

    Hada, M; Gersey, B; Saganti, P B; Wilkins, R; Cucinotta, F A; Wu, H

    2010-08-14

    Human risks from chronic exposures to both low- and high-LET radiation are of intensive research interest in recent years. In the present study, human epithelial cells were exposed in vitro to gamma-rays at a dose rate of 17 mGy/h or secondary neutrons of 25 mGy/h. The secondary neutrons have a broad energy spectrum that simulates the Earth's atmosphere at high altitude, as well as the environment inside spacecrafts like the Russian MIR station and the International Space Station (ISS). Chromosome aberrations in the exposed cells were analyzed using the multicolor banding in situ hybridization (mBAND) technique with chromosome 3 painted in 23 colored bands that allows identification of both inter- and intrachromosome exchanges including inversions. Comparison of present dose responses between gamma-rays and neutron irradiations for the fraction of cells with damaged chromosome 3 yielded a relative biological effectiveness (RBE) value of 26+/-4 for the secondary neutrons. Our results also revealed that secondary neutrons of low dose rate induced a higher fraction of intrachromosome exchanges than gamma-rays, but the fractions of inversions observed between these two radiation types were indistinguishable. Similar to the previous findings after acute radiation exposures, most of the inversions observed in the present study were accompanied by other aberrations. The fractions of complex type aberrations and of unrejoined chromosomal breakages were also found to be higher in the neutron-exposed cells than after gamma-rays. We further analyzed the location of the breaks involved in chromosome aberrations along chromosome 3, and observed hot spots after gamma-ray, but not neutron, exposures.

  8. Do Recent Advances in MR Technologies Contribute to Better Gamma Knife Radiosurgery Treatment Results for Brain Metastases?

    PubMed

    Hayashi, M; Yamamoto, M; Nishimura, C; Satoh, H

    2007-10-31

    The detection of intracerebral lesions has improved greatly with advancements in MR imaging, especially the greater sensitivity of the 1.5 Tesla unit versus the older 1.0 Tesla unit. We aimed to determine whether improvements in MR imaging have actually improved diagnostic capabilities and treatment outcomes in gamma knife radiosurgery (GKRS) for brain metastases (METs). Ours was a retrospective study of a consecutive series of 1179 patients (441 females, 738 males, mean age: 63 years, range: 19-92 years) with brain METs who underwent GKRS from 1998 to 2004. Our treatment policy was to irradiate all lesions visible on MR images during a single GKRS session. Mean and median tumor numbers were seven and three (range; 1-74). The 1179 patients were divided into two groups: a 1.0 T-group of 660 patients examined using a 1.0 Tesla MR unit before August,2002, and a 1.5 T-group of 519 examined using a 1.5 Tesla MR unit after September 2002. In the 1.5 T-group, lesion volumes as small as 0.004 cc were detected with a 5 mm slice thickness. The corresponding lesion size was 0.013 cc in the 1.0 T-group. One or more lesions invisible on a 5 mm slice study were additionally detected on a 2 mm slice study in 47.8% of patients in the 1.0 T-group and 25.2% in the 1.5 T-group (p<.0001). The median survival time (MST) in the 1.5 T-group was significantly longer than that in the 1.0 T-group (8.4 vs. 6.3 months, p=.0004). Due to biases in patient numbers between the two groups, we analyzed subgroups with KPS of 80% or better, no neurological deficits, stable primary tumors, lung cancer, tumor numbers of four or less and tumor volumes of 10.0 cc or smaller. In every subgroup analysis, the MSTs of the 1.5-Tesla group were significantly longer than those of the 1.0-Tesla group. The prognosis of a cancer patient is undoubtedly influenced by multiple factors. Nevertheless, we conclude that application of the 1.5 Tesla MR unit has had a favorable impact on diagnosis and GKRS treatment

  9. Neutron-gamma flux and dose calculations in a Pressurized Water Reactor (PWR)

    NASA Astrophysics Data System (ADS)

    Brovchenko, Mariya; Dechenaux, Benjamin; Burn, Kenneth W.; Console Camprini, Patrizio; Duhamel, Isabelle; Peron, Arthur

    2017-09-01

    The present work deals with Monte Carlo simulations, aiming to determine the neutron and gamma responses outside the vessel and in the basemat of a Pressurized Water Reactor (PWR). The model is based on the Tihange-I Belgian nuclear reactor. With a large set of information and measurements available, this reactor has the advantage to be easily modelled and allows validation based on the experimental measurements. Power distribution calculations were therefore performed with the MCNP code at IRSN and compared to the available in-core measurements. Results showed a good agreement between calculated and measured values over the whole core. In this paper, the methods and hypotheses used for the particle transport simulation from the fission distribution in the core to the detectors outside the vessel of the reactor are also summarized. The results of the simulations are presented including the neutron and gamma doses and flux energy spectra. MCNP6 computational results comparing JEFF3.1 and ENDF-B/VII.1 nuclear data evaluations and sensitivity of the results to some model parameters are presented.

  10. Comparative toxicity and micronuclei formation in Tribolium castaneum, Callosobruchus maculatus and Sitophilus oryzae exposed to high doses of gamma radiation.

    PubMed

    Ahmadi, Mehrdad; Mozdarani, Hossein; Abd-Alla, Adly M M

    2015-07-01

    The effects of gamma radiation on mortality and micronucleus formation in Tribolium castaneum Herbst, Callosobruchus maculatus (F.) and Sitophilus oryzae (L.) genital cells were evaluated. Two groups of healthy and active adult insects 1-3 and 8-10 days old were irradiated with various doses (50-200 Gy) gamma ray. Seven days post-irradiation; mortality rates and micronucleus formation were assessed in genital cells of the irradiated insects. The results show that with increasing gamma doses, the mortality rate of each species increased and T. castaneum and S. oryzae showed the low and high sensitivity respectively. It was shown that the micronucleus appearance in the tested insects had correlation with amount and intensity of radiation doses. Moreover our results indicate different levels in the genotoxicity of gamma radiation among the insects' genital cells under study. The frequency of micronuclei in genital cells of 1-3 days old insects exposed to 50 and 200 Gy were 12.6 and 38.8 Mn/1000 cells in T. castaneum, 20.8 and 46.8 Mn/1000 cells in C. maculatus and 16.8 and 57.2 Mn/1000 cells in S. oryzae respectively. A high sensitivity of the genital cells to irradiation exposure was seen in S. oryzae correlated with its high mortality rate compared with the other two species. These results might be indicative of inflicting chromosomal damage expressed as micronucleus in high mortality rates observed in the pest population; an indication of genotoxic effects of radiation on the studied species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Measurement of radon/thoron exhalation rates and gamma-ray dose rate in granite areas in Japan.

    PubMed

    Prasad, G; Ishikawa, T; Hosoda, M; Sahoo, S K; Kavasi, N; Sorimachi, A; Tokonami, S; Uchida, S

    2012-11-01

    Radon and thoron exhalation rates and gamma-ray dose rate in different places in Hiroshima Prefecture were measured. Exhalation rates were measured using an accumulation chamber method. The radon exhalation rate was found to vary from 3 to 37 mBq m(-2) s(-1), while the thoron exhalation rate ranged from 40 to 3330 mBq m(-2) s(-1). The highest radon exhalation rate (37 mBq m(-2) s(-1)) and gamma-ray dose rate (92 nGy h(-1)) were found in the same city (Kure City). In Kure City, indoor radon and thoron concentrations were previously measured at nine selected houses using a radon-thoron discriminative detector (Raduet). The indoor radon concentrations varied from 16 to 78 Bq m(-3), which was higher than the average value in Japan (15.5 Bq m(-3)). The indoor thoron concentration ranged from ND (not detected: below a detection limit of approximately 10 Bq m(-3)) to 314 Bq m(-3). The results suggest that radon exhalation rate from the ground is an influential factor for indoor radon concentration.

  12. Place of Gamma Knife Stereotactic Radiosurgery in Grade 4 Vestibular Schwannoma Based on Case Series of 86 Patients with Long-Term Follow-Up.

    PubMed

    Lefranc, Michel; Da Roz, Leila Maria; Balossier, Anne; Thomassin, Jean Marc; Roche, Pierre Hugue; Regis, Jean

    2018-06-01

    Grade IV vestibular schwannoma (Koos classification) is generally considered to be an indication for microsurgical resection or combined radiosurgery-microsurgery. However, the place of Gamma Knife stereotactic surgery (GK-SRS), either as first-line treatment or when progression of residual tumor compresses the brainstem, has not been clearly evaluated. This article reports the results of a large case series of patients with grade 4 vestibular schwannoma treated by GK-SRS. All consecutive patients with grade IV vestibular schwannoma treated by GK-SRS in our department between 1996 and 2011 with a minimum follow-up of 3 years were included in this study. 86 patients were treated by GK-SRS with a minimum follow-up of 3 years. Mean follow-up was 6.2 years (3-16 years). The mean age of the patients at the time of GK-SRS was 54.6 years (range: 23-84) and the sex ratio was 0.6. At the time of radiosurgery, no patient presented brainstem dysfunction prior to GK-SRS. 38 patients had functional hearing before treatment. One patient presented mild trigeminal neuralgia before GK-SRS. Tumor control with no clinical deterioration was obtained in 78 patients (90.7%). No radiation-induced brainstem or cranial nerve toxicity was observed in any of these patients. Functional hearing was maintained in 25 patients. 8 (9.3%) patients presented tumor growth and required microsurgical resection in 7 cases and ventricular shunt in 1 case. On the basis of this large series, GK-SRS appears to be a safe and effective treatment option for grade IV vestibular schwannoma for patients with no signs of brainstem dysfunction. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. Low Doses of Gamma-Irradiation Induce an Early Bystander Effect in Zebrafish Cells Which Is Sufficient to Radioprotect Cells

    PubMed Central

    Pereira, Sandrine; Malard, Véronique; Ravanat, Jean-Luc; Davin, Anne-Hélène; Armengaud, Jean; Foray, Nicolas; Adam-Guillermin, Christelle

    2014-01-01

    The term “bystander effect” is used to describe an effect in which cells that have not been exposed to radiation are affected by irradiated cells though various intracellular signaling mechanisms. In this study we analyzed the kinetics and mechanisms of bystander effect and radioadaptation in embryonic zebrafish cells (ZF4) exposed to chronic low dose of gamma rays. ZF4 cells were irradiated for 4 hours with total doses of gamma irradiation ranging from 0.01–0.1 Gy. In two experimental conditions, the transfer of irradiated cells or culture medium from irradiated cells results in the occurrence of DNA double strand breaks in non-irradiated cells (assessed by the number of γ-H2AX foci) that are repaired at 24 hours post-irradiation whatever the dose. At low total irradiation doses the bystander effect observed does not affect DNA repair mechanisms in targeted and bystander cells. An increase in global methylation of ZF4 cells was observed in irradiated cells and bystander cells compared to control cells. We observed that pre-irradiated cells which are then irradiated for a second time with the same doses contained significantly less γ-H2AX foci than in 24 h gamma-irradiated control cells. We also showed that bystander cells that have been in contact with the pre-irradiated cells and then irradiated alone present less γ-H2AX foci compared to the control cells. This radioadaptation effect is significantly more pronounced at the highest doses. To determine the factors involved in the early events of the bystander effect, we performed an extensive comparative proteomic study of the ZF4 secretomes upon irradiation. In the experimental conditions assayed here, we showed that the early events of bystander effect are probably not due to the secretion of specific proteins neither the oxidation of these secreted proteins. These results suggest that early bystander effect may be due probably to a combination of multiple factors. PMID:24667817

  14. [Efficacy comparison between needle-knife therapy and acupuncture-cupping for cervical spondylosis of cervical type].

    PubMed

    Cao, Li; Wang, Fan

    2014-05-01

    To compare the efficacy differences between needle-knife therapy and acupuncture-cupping for treatment of cervical spondylosis (CS) of cervical type. Sixty cases of CS were randomly divided into a needle-knife group (30 cases) and an acupuncture-cupping group (30 cases). The needle-knife therapy was applied at points among superior nuchal line of occipital bone, bilateral neck muscle, neck centerline, trapezius and medial border scapula for only once. In the acupuncture-cupping group, acupuncture was applied at Fengchi (GB 20), Fengfu (GV 16), Tianzhu (BL 10), Dazhui (GV 14), Jianjing (GB 21), Jiaji (Ex-B2, from C4 to C6), Houxi (SI 3) and Ashi point, followed by cupping on local skin, once every other day for totally six times. The score of neck stiffness and visual analogue scale (VAS) were observed before and after treatment, in follow-up of 1, 3 and 6 months after treatment in the two groups, and the efficacy was compared. In the needle-knife group, 9 cases were cured, 12 cases were markedly effective, 8 cases were effective and 1 case was failed; the total effective rate was 96.7% (29/30) and the cured and markedly effective rate was 70.0% (21/30). In the acupuncture-cupping group, 8 cases were cured, 9 cases were markedly effective, 11 cases were effective and 2 cases were failed; the total effective rate was 93.3% (28/30) and the cured and markedly effective rate was 56.7% (17/30). The difference of total effective rate in the two groups was not statistically significant (P > 0.05), but the cured and markedly effective rate of needle-knife group was significantly superior to that of acupuncture-cupping group (P < 0.05). The needle-knife therapy was significantly superior to acupuncture-cupping on improvement of neck stiffness in the follow-up of 1, 3, 6 months after treatment (P < 0.05, P < 0.001); both treatments were effective on relief of neck pain, but the needle-knife group had better effects in the follow-up of 3 and 6 months after treatment compared

  15. "Knife to skin" time is a poor marker of operating room utilization and efficiency in cardiac surgery.

    PubMed

    Luthra, Suvitesh; Ramady, Omar; Monge, Mary; Fitzsimons, Michael G; Kaleta, Terry R; Sundt, Thoralf M

    2015-06-01

    Markers of operation room (OR) efficiency in cardiac surgery are focused on "knife to skin" and "start time tardiness." These do not evaluate the middle and later parts of the cardiac surgical pathway. The purpose of this analysis was to evaluate knife to skin time as an efficiency marker in cardiac surgery. We looked at knife to skin time, procedure time, and transfer times in the cardiac operational pathway for their correlation with predefined indices of operational efficiency (Index of Operation Efficiency - InOE, Surgical Index of Operational Efficiency - sInOE). A regression analysis was performed to test the goodness of fit of the regression curves estimated for InOE relative to the times on the operational pathway. The mean knife to skin time was 90.6 ± 13 minutes (23% of total OR time). The mean procedure time was 282 ± 123 minutes (71% of total OR time). Utilization efficiencies were highest for aortic valve replacement and coronary artery bypass grafting and least for complex aortic procedures. There were no significant procedure-specific or team-specific differences for standard procedures. Procedure times correlated the strongest with InOE (r = -0.98, p < 0.01). Compared to procedure times, knife to skin is not as strong an indicator of efficiency. A statistically significant linear dependence on InOE was observed with "procedure times" only. Procedure times are a better marker of OR efficiency than knife to skin in cardiac cases. Strategies to increase OR utilization and efficiency should address procedure times in addition to knife to skin times. © 2015 Wiley Periodicals, Inc.

  16. Characteristics of Bone Injuries Resulting from Knife Wounds Incised with Different Forces.

    PubMed

    Humphrey, Caitlin; Kumaratilake, Jaliya; Henneberg, Maciej

    2017-11-01

    The aim of this research was to experimentally determine the characteristics of incised bone wounds, which are commonly found in defense injuries. A specially constructed pivoting arm device was used to inflict wounds with controlled forces and direction. Five knives were selected to inflict the wounds on porcine forelimbs. Eight incised wounds were made per knife per force. A larger knife and a greater force caused longer and wider bone wounds. Comparisons of individual knives at the two forces produced varying results in the bone wounds. A correlation was seen between the force and the length (r = 0.69), width (r = 0.63), and depth (r = 0.57) of bone wounds. Serrated-edge and nonserrated knives can be distinguished from the appearance of the wound. The outcomes may be applicable in forensic investigations to ascertain the forces associated with incised wounds and identify the specific knife used. © 2017 American Academy of Forensic Sciences.

  17. Bark Separation During Chipping With a Parallel Knife Chipper

    Treesearch

    John R. Erickson

    1968-01-01

    Five winter-cut northern species were chipped in a frozen and unfrozen condition with a parallel knife chipper. The degree of bark separation during chipping and a relative gradation of chip size are reported.

  18. Adjustable knife cuts honeycomb material to specified depth

    NASA Technical Reports Server (NTRS)

    Rauschl, J. A.

    1966-01-01

    Calibrated, adjustable knife cuts aluminum honeycomb or other soft materials to a desired depth. The frame of the device accommodates standard commercial blades. Since the blade is always visible to the operator, the device can be used on any straight or irregular layout line.

  19. Effects of exposing ostrich eggs to doses of gamma radiation on hatchability, growth performance, and some blood biochemicals of hatched chicks.

    PubMed

    Mahrose, Khalid; Elsayed, Mohammed; Basuony, Hamdy; Gouda, Nour

    2016-11-01

    Effects of radiating ostrich eggs before incubation on hatchability, growth performance, and some blood components of ostrich chicks were studied. 72 ostrich eggs were randomly distributed into four groups. The first group was kept without exposure to gamma radiation (control). The 2nd, 3rd, and 4th groups were exposed to 0.8, 1.6, and 3.2 Gy, respectively, of 60 Co gamma rays just before incubation. Total bacterial counts (×10 3  CFU) were significantly increased with the increase in gamma radiation levels before incubation. Feed conversion was lower (P ≤ 0.01) in the control group than those irradiated. Embryonic mortality rate (%), hatchability (%) and chick weight at hatch, body weight, daily body weight gain, feed consumption, and all of hematology parameters studied were insignificantly fluctuated with the doses of gamma rays used. Serum concentrations of total protein, albumen, globulin, glucose, and triiodothyronin of the chicks from eggs of the control and the 1st group were significantly the highest. Chicks of the control group had significantly the lowest values of serum concentrations of uric acid, creatinine, triglyceride, total cholesterol, ALT, and AST when compared with the other groups. In conclusion, radiation of ostrich eggs before incubation with a dose of 0.8 Gy gamma has a stimulative effect upon the metabolism of hatched chicks.

  20. Stopping power and dose calculations with analytical and Monte Carlo methods for protons and prompt gamma range verification

    NASA Astrophysics Data System (ADS)

    Usta, Metin; Tufan, Mustafa Çağatay; Aydın, Güral; Bozkurt, Ahmet

    2018-07-01

    In this study, we have performed the calculations stopping power, depth dose, and range verification for proton beams using dielectric and Bethe-Bloch theories and FLUKA, Geant4 and MCNPX Monte Carlo codes. In the framework, as analytical studies, Drude model was applied for dielectric theory and effective charge approach with Roothaan-Hartree-Fock charge densities was used in Bethe theory. In the simulations different setup parameters were selected to evaluate the performance of three distinct Monte Carlo codes. The lung and breast tissues were investigated are considered to be related to the most common types of cancer throughout the world. The results were compared with each other and the available data in literature. In addition, the obtained results were verified with prompt gamma range data. In both stopping power values and depth-dose distributions, it was found that the Monte Carlo values give better results compared with the analytical ones while the results that agree best with ICRU data in terms of stopping power are those of the effective charge approach between the analytical methods and of the FLUKA code among the MC packages. In the depth dose distributions of the examined tissues, although the Bragg curves for Monte Carlo almost overlap, the analytical ones show significant deviations that become more pronounce with increasing energy. Verifications with the results of prompt gamma photons were attempted for 100-200 MeV protons which are regarded important for proton therapy. The analytical results are within 2%-5% and the Monte Carlo values are within 0%-2% as compared with those of the prompt gammas.