Dosimetric comparison of Zap-X and CyberKnife stereotactic radiosurgery for single brain metastasis / 中华放射肿瘤学杂志

Objective:To evaluate the dosimetric characteristics of Zap-X system and CyberKnife (CK) G4 system of stereotactic radiosurgery (SRS) for single brain metastasis.Methods:Twelve patients with single brain metastasis had been treated with CK were selected retrospectively. The prescribed dose of planning target volume (PTV) was 18-24 Gy for 1-3 fractions. The PTV was ranged from 0.44 to 11.52 cm 3. The 12 patients were re-planned in the Zap-X planning system using the same prescription dose and organs at risk constraints, and the prescription dose of PTV was normalized to 70% for both Zap-X and CK. The planning parameters and dosimetric parameters of PTV and organs at risk were compared and evaluated between two plans. All data were read at MIM Maestro. A paired Wilcoxon' signed-rank test was adopted for statistical analysis. A P value of less than 0.05 was considered as statistical significance. Results:For the target coverage, CK was significantly higher than Zap-X (99.14±0.57% vs. 97.55±1.34%, P<0.01), but Zap-X showed a higher conformity index (0.81±0.05 vs. 0.77±0.07, P<0.05), a lower Paddick gradient index (2.98±0.24 vs. 3.15±0.38), and a higher gradient score index (GSI) than CK. The total monitor unit (MU) of Zap-X was significantly lower than that of CK (11 627.63 ±5 039.53 vs. 23 522.16 ±4 542.12, P<0.01) and the treatment time was shorter than that of CK [(25.08 ±6.52) vs. (38.08 ±4.74) min, P<0.01]. Zap-X had lower dose volumes than CK for the dose of brain ( P<0.05). Zap-X had a lower D mean and D max of brainstem (both P<0.05), but a higher value of eyes and lens. For optic nerves and optic chiasm, there were no significant differences between two groups. In addition, for the protection of skin (V 22.5 Gy), Zap-X seemed better than CK [(4.15±4.48) vs. (4.37±4.50) cm 3, P<0.05]. Conclusions:For SRS treating single brain metastasis, Zap-X could provide a high quality plan equivalent to or even better than CK, especially reducing the treatment time. With continuous improvement and upgrading of Zap-X system, it may become a new SRS platform for the treatment of brain metastasis.

Beam dosimetric comparison between Zap-X and G4 CyberKnife / 中华放射肿瘤学杂志

Objective:To compare the dosimetric characteristics of beams between Zap-X and G4 CyberKnife and provide reference for clinical application of Zap-X.Methods:PTW three-dimensional water tank and dosimetry diode ionization chamber were used to measure the two orthogonal off-axis ratio and field size at isocenter of 7 different collimators (5 mm, 7.5 mm, 10 mm, 12.5 mm, 15 mm, 20 mm and 25 mm) of Zap-X and CyberKnife at the water depth of maximum dose, 50 mm, 100 mm, and 200 mm. The penumbra, flatness, symmetry and field size under each parameter condition were analyzed by using PTW supporting software PTW MEPHYSTO (version 5.1). Data analysis and graph were performed using Origin 2021 software.Results:With the same collimator, the dose plateau area of Zap-X was wider than that of G4 CyberKnife, and the dose fall-off at the field edge of Zap-X system was faster. With the increase of the collimator, the penumbra of Zap-X and CyberKnife tended to become larger, and the flatness tended to become smaller, the penumbra and flatness of Zap-X were significantly smaller than those of CyberKnife. Both of them had excellent symmetry (<1%), and the symmetry results of CyberKnife (<0.39%) were better than that of Zap-X (0.99%). The accuracy of Zap-X collimator size at isocenter was better than that of CyberKnife.Conclusion:Compared with G4 CyberKnife, Zap-X system has smaller penumbra, better flatness and higher accuracy of collimator size, which is suitable for stereotactic radiosurgery.

Evaluation of the quality and efficiency of SRT plans for intracranial tumors using Fixed and Iris collimators of CyberKnife / 中华放射肿瘤学杂志

Objective To discuss and evaluate the dosimetric characteristics of different plans implementing stereotactic radiotherapy(SRT)for intracranial tumors using Fixed and Iris collimators of CyberKnife VSI.Methods Twenty patients with intracranial tumors were selected and divided into group A with a small target volume(≤30 cm3)and group B with a large target volume(≥30 cm3). There were 10 patients in each group,and the prescribed dose to the target was 21 Gy in 3 fractions. For each patient, two treatment plans were designed using Fixed and Iris collimators. By analyzing the dosimetric parameters such as conformity index(CI),homogeneity index(HI), gradient index(GI), gradient score index(GSI), and organs at risk (OAR),the quality and efficiency of the plans were evaluated in order to discuss the beam characteristics for two sets of collimators. The difference was analyzed with the paired t-test. Results The mean time of Iris plan for delivering was significantly less than that of Fixed plan(group A:P=0.001;group B:P=0.000). In group B,the peripheral dose(20% and 10% of the prescribed dose)volumes of Fixed plan were significantly less than those of Iris plan(P=0.001 and 0.009). For OAR,D minof the visual pathway and D meanor D minof the eyeball in group B were significantly different between Fixed and Iris plans(all P<0.05), while in group A, only D minof the optic chiasm was significantly different between the two plans(P=0.043). For the other parameters of targets,there were no significant differences between Fixed and Iris plans in both groups(all P>0.05). Conclusions Apart from less treatment time in the Iris plan, there are no significant dosimetric differences between the two collimator plans of CyberKnife VSI in treating small intracranial tumor. For the large and complex tumor,although Iris plan meets the requirement for OAR dose constraints,its low-dose volumes are larger than those of Fixed plan. Further studies of the dosimetric characteristics in CyberKnife should be done.

Preparation and biodistribution of 2-(5-[18F] fluoro-pentyl)-2-methyl-malonic acid and its clinical application / 中华核医学与分子影像杂志

Objective To synthesize 2-(5-[18 F] fluoro-pentyl)-2-methyl-malonic acid (18 F-ML-10) and to investigate the biodistribution in mice and the primary clinical application.Methods 18F-ML-10 was synthesized by domestic synthesis module MF-2V-IT-1.Quality control of the probe was performed after automated synthesis.The biological characteristics of 18F-ML-10 were assessed by biodistribution assay on male Kunming mice and microPET imaging on a male SD rat.Six patients with brain metastasis (4males,2 females,and age 21-68 years) were enrolled in this study.18F-ML-10 PET images were acquired before and at 48 h after radiotherapy.SUVmean and SUVmax of ROI were calculated.GTV changes were measured by MRI before and 3 months after radiotherapy.Response of brain metastasis to radiotherapy was assessed by PET imaging with 18F-ML-10.Two-sample t test was used.Results The non-corrected radiochemical yield of 18F-ML-10 was (26.5±7.3)％ with acceptable quality.The radiochemical purity exceeded 99％.18F-ML-10 was excreted through the kidneys,and the radiouptake in the blood was declined rapidly.The radiotracer accumulation was low in most of other organs.The testis showed a significant uptake.The SUVmean and SUVmax after radiotherapy (5.54±2.72 and 7.29±3.09) were significantly higher than the baseline values(3.81±1.13 and 4.97±1.05;t=2.670,2.663,both P＜0.05).The GTV after radiotherapy was significantly lower than the baseline value:(13.14±9.39) cm3 vs (23.34± 18.13) cm3;t =3.002,P＜0.05.Conclusions 18F-ML-10 could be synthesized reliably and repeatedly by domestic synthesis module.It has satisfactory properties in vivo and is probably suitable for early assessment of the response to radiotherapy in patients with brain metastasis.

Vision deterioration after transsphenoidal surgery for removal of pituitary adenoma / 中华外科杂志

<p><b>OBJECTIVE</b>To explore the mechanism and strategies of prevention and treatment of vision deterioration after transsphenoidal surgery for removal of pituitary adenoma.</p><p><b>METHODS</b>From January 1980 to February 2001, 1 412 patients were operated on by transsphenoidal surgery to remove pituitary adenoma. Fourteen patients experienced vision deterioration after operation. Clinical data from the 14 patients with vision deterioration were analyzed retrospectively.</p><p><b>RESULTS</b>In this group, the incidence of vision deterioration was 0.99%. Over packing of the adenoma bed was seen in 5 patients, apoplexy of residual tumor in 3, high intracranial pressure in 2, vascular spasm in 2, injury of the optic nerve in the cannel in 1 and unknown reason in 1.</p><p><b>CONCLUSIONS</b>Vision deterioration is a severe complication after transsphenoidal surgery. Early diagnosis and treatment can greatly improve the vision.</p>

Cyclosporin A exerts neuroprotective effects after diffuse axonal injury in the rat / 解放军医学杂志

Objective To determine whether cyclosporin A(CsA) could exert neuroprotective effects after diffuse axonal injury (DAI) in the rat. Methods Twenty four SD rats were randomly assigned into three groups: non injur group ( n =8); control brain injury group ( n =8), in which normal saline was given; and experimental group ( n =8), the injured rats were treated with CsA. The beam balance test device and Morris water maze were used to test for balance and cognitive performance. Results Control brain injury animals displayed severe defects in balance and cognitive performande after diffuse axonal injury. Compared with control brain injury animals, rats treated with CsA displayed better motor performance in beam balance tests and improved learning ability in the Morris water maze. Conclusions It is demonstrated that CsA exhibits substantial neuroprotective activity in a rat model of DAI. These findings support that CsA is a useful therapeutic agent in the treatment of DAI.

Experimental studies on the expression of amyloid ?-protein precursor in early stage of diffuse axonal injury in rats / 解放军医学杂志

s Objective To observe the changes in the expression of ?-amyloid precursor protein (?-APP) in selected brain areas in early stage of diffuse axonal injury (DAI) in rats. Methods DAI was induced in SD rats by a self-made rotating injury device. 16 rats in injury group were sacrificed by decapitation at 3 hours and 6 hours post-trauma, while the other 8 rats in sham injury group were put to death after 24 hours. The samples of the rat brain were stained with ?-APP for immunohistochemistry in order to detect the early stage pathological changes in subcortex white matter, hippocampus, corpus callosum and brain stem at different time points. Results The ?-APP expression was positive at 3 hours and was particularly strong at 6 hours after injury. The results of semi-quantitative analysis showed a significant differentiation of 3 hours and 6 hours in the immuno-positive expression of brain stem, corpus callosum and hippocampus. Histological results demonstrated that DAI occurred in all rats of injury group. Conclusion ?-APP is a kind of sensitive and useful immunochemical marker for early DAI diagnosis, and it indicates axonal lesion or breakage.

The experimental study on changes in proton magnetic resonance spectroscopy at early stage of diffuse axonal injury in rats / 解放军医学杂志

s Objective To observe the changes in neurochemical metabolites at early stage of DAI in rats with MRS technique. Methods DAI was induced by a self-made rotating injury device in Sprague-Dawley (SD) rats (n=16). MRS was used to evaluate the changes in neurochemical metabolites before-trauma, 2 hours and 3 hours after the trauma. The data were analyzed by statistical analysis system. Results MRS demonstrated that contents of both NAA/Cr and Cho/Cr of corpus callosum were decreased obviously 3 hours posttrauma, and differences between those before trauma and those after trauma were statistically significant. The content of NAA/Cr of the brain stem was declined at 2 hours also with significant difference compared with that before trauma. There was no significant difference in values between 2 and 3 hours. The content of Cho/Cr of the brain stem was significantly decreased 3 hours after the trauma. Conclusions MRS technique has a high sensitivity in diagnosing microscopic pathology following DAI and functional defect of neuron and axon, as shown by significant decrease in NAA/Cr and Cho/Cr at early stage (i.e. 2-3 hours) after trauma.