The measure analysis and QA system for gamma knife dose field and its pivotal techniques are described in this paper. By using our own measuring tools and analysis software, we have made a testing analysis about the HuaYuan Gamma Knife dose field with a satisfactory result.
Equipment Design ; Radiosurgery ; instrumentation ; methods ; Radiotherapy Dosage

OBJECTIVE: We investigated the effect of optimization in dose-limiting shell method on the dosimetric quality of CyberKnife (CK) plans in treating brain metastases (BMs).METHODS: We selected 19 BMs previously treated using CK between 2014 and 2015. The original CK plans (CKoriginal) had been produced using 1 to 3 dose-limiting shells : one at the prescription isodose level (PIDL) for dose conformity and the others at lowisodose levels (10–30% of prescription dose) for dose spillage. In each case, a modified CK plan (CKmodified) was generated using 5 dose-limiting shells : one at the PIDL, another at intermediate isodose level (50% of prescription dose) for steeper dose fall-off, and the others at low-isodose levels, with an optimized shell-dilation size based on our experience. A Gamma Knife (GK) plan was also produced using the original contour set. Thus, three data sets of dosimetric parameters were generated and compared.RESULTS: There were no differences in the conformity indices among the CKoriginal, CKmodified, and GK plans (mean 1.22, 1.18, and 1.24, respectively; p=0.079) and tumor coverage (mean 99.5%, 99.5%, and 99.4%, respectively; p=0.177), whereas the CKmodified plans produced significantly smaller normal tissue volumes receiving 50% of prescription dose than those produced by the CKoriginal plans (p < 0.001), with no statistical differences in those volumes compared with GK plans (p=0.345).CONCLUSION: These results indicate that significantly steeper dose fall-off is able to be achieved in the CK system by optimizing the shell function while maintaining high conformity of dose to tumor.
Brain ; Dataset ; Methods ; Neoplasm Metastasis ; Prescriptions ; Radiosurgery

In order to guarantee the safety and accuracy of the whole treating process as well as better link up of each section during the treatment, we did research in order to establish a project concerning the process quality control (PQC) of treating liver cancer with CyberKnife. From the safety and accuracy point of view, we divided the whole process of treating liver cancer with CyberKnife into ten links, i.e. the registration of patients' information, the im plantation of fiducial markers, fixation of body posture, CT localization, target delineation, design of the treatment plan, quality assurance in physics, implementation of the treatment plan, inspection on the correctness and data archiving. We analyzed the possible mistakes in each link and the consequences brought by them. To smoothly connect all the links, a special part "Attention" was added between every two links. Various wrong operations which may influence the safety and accuracy of treatment were illustrated, and the consequences brought by them were also ex plained. The "Attention" part among links offers important information for the next step, and gives us reminding and warnings. The project of quality control covers all the important links when treating liver cancer with Cy berKnife. It offers regulations, reminding and warning for us so that the safety and accuracy of treatment can be guaranteed, and the work of all staff could be closely connected.
Humans ; Liver Neoplasms ; surgery ; Quality Control ; Radiosurgery ; methods

Fourteen patients with pancreatic carcinoma were selected. Two treatment plans were designed for each patient, including gamma knife and Tomotherapy. The dose characteristics were evaluated by DVH and were compared. The results showed that the gamma knife plan had the higher maximal and mean target dose than Tomotherapy. Body gamma knife can increase the target dose significantly, and decrease the OAR dose. Tomotherapy had excellent dose-target conformality, and it can control doses of duodenum and stomach easily, but it had larger low dose region.
Humans ; Pancreatic Neoplasms ; radiotherapy ; Radiosurgery ; methods ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods

This paper presents a novel x-ray dose testing water tank used for the stereotactic radiation therapy system, including its constitution, structure and the method of using it. The water tank has a simple structure of inner and outer sleeves which are connected through a drowned pump and a water pipe in order to control the water level of the tank. The water tank featuring autoregulation and easy use is worthy of clinical application and popularization.
Equipment Design ; Radiosurgery ; instrumentation ; methods ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; instrumentation ; methods

PURPOSE: Tinnitus is a very common symptom of vestibular schwannoma, present in 45 to 80% of patients. We evaluated changes in tinnitus after translabyrinthine microsurgery (TLM) or gamma knife radiosurgery (GKS). MATERIALS AND METHODS: Among 78 patients with vestibular schwannoma who underwent TLM or GKS at Severance Hospital from 2009-2012, 46 patients with pre- or postoperative tinnitus who agreed to participate were enrolled. Pure tone audiometry, tinnitus handicap inventory (THI), visual analogue scale (VAS) scores for loudness, awareness, and annoyance were measured before and after treatment. Changes of THI and VAS were analysed and compared according to treatment modality, tumour volume, and preoperative residual hearing. RESULTS: In the TLM group (n=27), vestibulocochlear nerves were definitely cut. There was a higher rate of tinnitus improvement in TLM group (52%) than GKS group (16%, p=0.016). The GKS group had a significantly higher rate of tinnitus worsening (74%) than TLM group (11%, p<0.001). Mean scores of THI and VAS scores significantly decreased in the TLM group in contrast to significant increases in the GKS group. Tumor volume and preoperative hearing did not affect the changes in THI or VAS. CONCLUSION: GKS can save vestibulocochlear nerve continuity but may damage the cochlea, cochlear nerve and can cause worsening tinnitus. In cases where hearing preservation is not intended, microsurgery with vestibulocochlear neurectomy during tumor removal can sometimes relieve or prevent tinnitus.
Adult ; Female ; Humans ; Male ; Middle Aged ; Neuroma, Acoustic/*surgery ; Radiosurgery/*methods ; Tinnitus/*surgery ; Treatment Outcome

Dural arteriovenous fistula (DAVF) have been treated by transarterial or transvenous embolization, surgery, and radiosurgery. Besides these treatment options, the external compression technique is a non-invasive, low-cost form of treatment. This article reports that a 60-year-old man with DAVF between multiple arterial branches and transverse/sigmoid sinus was treated by repeated external manual compression method.
Arteriovenous Fistula ; Central Nervous System Vascular Malformations* ; Humans ; Methods ; Middle Aged ; Radiosurgery ; Tinnitus*

Dural arteriovenous fistula (DAVF) have been treated by transarterial or transvenous embolization, surgery, and radiosurgery. Besides these treatment options, the external compression technique is a non-invasive, low-cost form of treatment. This article reports that a 60-year-old man with DAVF between multiple arterial branches and transverse/sigmoid sinus was treated by repeated external manual compression method.
Arteriovenous Fistula ; Central Nervous System Vascular Malformations* ; Humans ; Methods ; Middle Aged ; Radiosurgery ; Tinnitus*

Humans ; Imaging, Three-Dimensional ; Neoplasms ; radiotherapy ; surgery ; Radiosurgery ; instrumentation ; methods ; Tomography, X-Ray Computed

PURPOSE: This study was conducted to compare clinical outcomes and treatment-related toxicities after stereotactic body radiation therapy (SBRT) with two different dose regimens for small hepatocellular carcinomas (HCC) ≤3 cm in size. MATERIALS AND METHODS: We retrospectively reviewed 44 patients with liver-confined HCC treated between 2009 and 2014 with SBRT. Total doses of 45 Gy (n = 10) or 60 Gy (n = 34) in 3 fractions were prescribed to the 95% isodose line covering 95% of the planning target volume. Rates of local control (LC), intrahepatic failure-free survival (IHFFS), distant metastasis-free survival (DMFS), and overall survival (OS) were calculated using the Kaplan-Meier method. RESULTS: Median follow-up was 29 months (range, 8 to 64 months). Rates at 1 and 3 years were 97.7% and 95.0% for LC, 97.7% and 80.7% for OS, 76% and 40.5% for IHFFS, and 87.3% and 79.5% for DMFS. Five patients (11.4%) experienced degradation of albumin-bilirubin grade, 2 (4.5%) degradation of Child-Pugh score, and 4 (9.1%) grade 3 or greater laboratory abnormalities within 3 months after SBRT. No significant difference was seen in any oncological outcomes or treatment-related toxicities between the two dose regimens. CONCLUSIONS: SBRT was highly effective for local control without severe toxicities in patients with HCC smaller than 3 cm. The regimen of a total dose of 45 Gy in 3 fractions was comparable to 60 Gy in efficacy and safety of SBRT for small HCC.
Carcinoma, Hepatocellular ; Dose Fractionation ; Follow-Up Studies ; Humans ; Methods ; Radiosurgery ; Retrospective Studies