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Objective@#Body mass index (BMI) is a major determinant of N-terminal pro-brain natriuretic peptide (NT-proBNP). However, the relationship of BMI with pneumonia has not been entirely characterized. @*Methods@#Adult patients with pneumonia, who visited the emergency department from January 2017 to December 2019, were included. According to BMI, they were divided into two groups, including normal-weight and obesity groups. Data were retrospectively reviewed via the prospectively collected pneumonia registry and medical chart. NT-proBNP, BMI and pneumonia severity index (PSI) were determined for all subjects. The moderating effect between NT-proBNP and BMI was examined by entering interaction terms into the multivariable regression model predicting mortality. Using the area under the curve (AUC), the predictive performance of NT-proBNP was evaluated. @*Results@#Of 327 enrolled patients, 118 patients belonged to the obesity group. In a multivariable model including BMI, NT-proBNP was identified as an independent predictor of mortality. The AUC of the adjusted NT-proBNP including BMI, significantly increased the AUC of the adjusted NT-proBNP excluding BMI and tended to be superior to that of PSI. A positively significant BMI-by-NT-proBNP interaction for mortality was observed. NT-proBNP showed significant prognostic power in both BMI groups, but NT-proBNP of the obesity group had significantly higher AUC than that of the normalweight group. In the obesity group, the AUC of NT-proBNP tended to be higher than that of PSI. @*Conclusion@#BMI is a significant factor enhancing the prognostic power of NT-proBNP in pneumonia. The prognostic utility of NT-proBNP was significantly differed by BMI groups, which is more useful in the obesity group than the normalweight group.
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Purpose@#The aims of the present study were twofold. First, the research investigated the effect of an individual’s risk factors and the prevalence of psychotropic drugs on QTc prolongation, TdP (torsades de pointes), and death. Second, the study compared the risk scoring systems (the Mayo Pro-QT risk score and the Tisadale risk score) on QTc prolongation. @*Methods@#The medical records of intoxicated patients who visited the emergency department between March 2010 and February 2019 were reviewed retrospectively. Among 733 patients, the present study included 426 psychotropic drug-intoxicated patients.The patients were categorized according to the QTc value. The known risk factors of QTc prolongation were examined, and the Mayo Pro-QT risk score and the Tisadale risk score were calculated. The analysis was performed using multiple logistic regression, Spearman correlation, and ROC (receiver operating characteristic). @*Results@#The numbers in the mild to moderate group (male: 470≤QTc<500 ms, female: 480≤QTc<500 ms) and severe group (QTc≥500 ms or increase of QTc at least 60ms from baseline, both sex) were 68 and 95, respectively. TdP did not occur, and the only cause of death was aspiration pneumonia. The statically significant risk factors were multidrug intoxications of TCA (tricyclic antidepressant), atypical antipsychotics, an atypical antidepressant, panic disorder, and hypokalemia. The Tisadale risk score was larger than the Mayo Pro-QT risk score. @*Conclusion@#Multiple psychotropic drugs intoxication (TCA, an atypical antidepressant, and atypical antipsychotics), panic disorder, and hypokalemia have been proven to be the main risk factors of QTc prolongation, which require enhanced attention. The present study showed that the Tisadale score had a stronger correlation and predictive accuracy for QTc prolongation than the Mayo Pro-QT score. As a result, the Tisadale risk score is a crucial assessment tool for psychotropic drug-intoxicated patients in a clinical setting.
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Purpose@#The aims of the present study were twofold. First, the research investigated the effect of an individual’s risk factors and the prevalence of psychotropic drugs on QTc prolongation, TdP (torsades de pointes), and death. Second, the study compared the risk scoring systems (the Mayo Pro-QT risk score and the Tisadale risk score) on QTc prolongation. @*Methods@#The medical records of intoxicated patients who visited the emergency department between March 2010 and February 2019 were reviewed retrospectively. Among 733 patients, the present study included 426 psychotropic drug-intoxicated patients.The patients were categorized according to the QTc value. The known risk factors of QTc prolongation were examined, and the Mayo Pro-QT risk score and the Tisadale risk score were calculated. The analysis was performed using multiple logistic regression, Spearman correlation, and ROC (receiver operating characteristic). @*Results@#The numbers in the mild to moderate group (male: 470≤QTc<500 ms, female: 480≤QTc<500 ms) and severe group (QTc≥500 ms or increase of QTc at least 60ms from baseline, both sex) were 68 and 95, respectively. TdP did not occur, and the only cause of death was aspiration pneumonia. The statically significant risk factors were multidrug intoxications of TCA (tricyclic antidepressant), atypical antipsychotics, an atypical antidepressant, panic disorder, and hypokalemia. The Tisadale risk score was larger than the Mayo Pro-QT risk score. @*Conclusion@#Multiple psychotropic drugs intoxication (TCA, an atypical antidepressant, and atypical antipsychotics), panic disorder, and hypokalemia have been proven to be the main risk factors of QTc prolongation, which require enhanced attention. The present study showed that the Tisadale score had a stronger correlation and predictive accuracy for QTc prolongation than the Mayo Pro-QT score. As a result, the Tisadale risk score is a crucial assessment tool for psychotropic drug-intoxicated patients in a clinical setting.
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This correction is being published to correct the order of the first and second authors' names in the above article.
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OBJECTIVES@#The objective of this study was to investigate the pain status, pain management methods, and pain experience after treatment among patients suffering from chronic non-cancer pain due to spinal disease.SUMMARY OF LITERATURE REVIEW: No thorough investigation of the current status of chronic non-cancer pain management in patients with spinal disease has recently been reported.@*MATERIALS AND METHODS@#We surveyed 330 patients with chronic non-cancer pain who visited spine clinics in Korea.@*RESULTS@#Prior to treatment, 86.7% of the patients had severe pain and 99.4% of the patients had taken oral analgesics for pain control. After treatment, the percent of patients with severe pain was reduced to 42.1%, and 52.4% of patients responded that they experienced intermittent pain. End of dose failure was experienced by 29.1% of patients, and 41.7% of patients experienced pain again 3–6 hours after taking analgesics. Furthermore, 8.2% of patients experienced breakthrough pain, and 29.1% of patients experienced pain that interfered with sleeping.@*CONCLUSIONS@#Many patients with chronic pain reported experiencing pain due to end of dose failure after medication. As the causes of chronic pain are complex, appropriate analgesics should be considered and selected for effective pain management.
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STUDY DESIGN: Cross-sectional, multi-center survey study. OBJECTIVES: The objective of this study was to investigate the pain status, pain management methods, and pain experience after treatment among patients suffering from chronic non-cancer pain due to spinal disease. SUMMARY OF LITERATURE REVIEW: No thorough investigation of the current status of chronic non-cancer pain management in patients with spinal disease has recently been reported. MATERIALS AND METHODS: We surveyed 330 patients with chronic non-cancer pain who visited spine clinics in Korea. RESULTS: Prior to treatment, 86.7% of the patients had severe pain and 99.4% of the patients had taken oral analgesics for pain control. After treatment, the percent of patients with severe pain was reduced to 42.1%, and 52.4% of patients responded that they experienced intermittent pain. End of dose failure was experienced by 29.1% of patients, and 41.7% of patients experienced pain again 3–6 hours after taking analgesics. Furthermore, 8.2% of patients experienced breakthrough pain, and 29.1% of patients experienced pain that interfered with sleeping. CONCLUSIONS: Many patients with chronic pain reported experiencing pain due to end of dose failure after medication. As the causes of chronic pain are complex, appropriate analgesics should be considered and selected for effective pain management.
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Humans , Analgesics , Breakthrough Pain , Chronic Pain , Korea , Pain Management , Spinal Diseases , SpineABSTRACT
STUDY DESIGN: Retrospective study. OBJECTIVES: To evaluate the efficacy of cervical expansive laminoplasty for patients with quadriplegia due to traumatic cervical spinal cord injury (SCI) without skeletal injury. SUMMARY OF LITERATURE REVIEW: There are a few studies on the surgical results for acute cervical SCI without bony injury. MATERIALS AND METHODS: From 2003 to 2010, among the patients who visited emergency room with post-traumatic quadriplegia, 12 patients who had underwent cervical expansive laminoplasty for acute cervical SCI without body injury and cord compression on MR images were included in this study. We evaluate the pre-operative swelling on MRI, the change of neurologic symptoms at pre-, post operative state, respiration state, complication and survival period. RESULTS: The average of motor index scores at the time of admission to the emergency room was 23 (4–30), and the average was changed to 29(4–43) during the follow-up period. No significant neurological improvement was observed in 11 cases except 1 case. The average time for operation after the injury was 26 hours(9–72). 4 patients showed paradoxical respiration when they first visited emergency room and the symptom continued after the operation and during follow-up periods. Another 4 patients showed paradoxical respiration after the operation. In all 8 cases who showed paradoxical respiration, tracheostomy and occasional ventilation were needed. In the follow-up period, 6 patients died due to respiratory failure within 1 year after the surgery. All these patients presented severe spinal cord edema on preoperative MRI with paradoxical respiration. CONCLUSIONS: Efficacy of expansive laminoplasty for quadriplegic patients due to acute cervical SCI without bony injury may be limited. In many patients, no significant neurological recovery was observed but it was clearly identified that prognosis was related to the grades of spinal cord edema and paradoxical respiration.
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Humans , Cervical Cord , Edema , Emergency Service, Hospital , Follow-Up Studies , Laminoplasty , Magnetic Resonance Imaging , Neurologic Manifestations , Prognosis , Quadriplegia , Respiration , Respiratory Insufficiency , Retrospective Studies , Spinal Cord , Tracheostomy , VentilationABSTRACT
STUDY DESIGN: Retrospective study. OBJECTIVES: To evaluate the validity of the thoracolumbar injury classification system (TLICS) when making treatment decisions in a group of thoracolumbar fracture patients. SUMMARY OF LITERATURE REVIEW: Few studies have evaluated the validity of the TLICS in consecutively treated patients, although many have evaluated the application of the TLICS to thoracolumbar injuries. MATERIALS AND METHODS: A retrospective study was performed among the 230 patients who were treated from 2003 to 2015 in our hospital for thoracolumbar injuries. Evaluations were made of clinical outcomes and radiologic results, and each case was analysed and scored according to the American Spinal Injury Association scale, the Magerl/AO classification, and the TLICS classification by 2 spinal surgeons. RESULTS: Of the 230 patients, 116 (50.4%) received conservative treatment and 114 (49.6%) received surgical treatment. Of the 116 patients who received conservative treatment, 112 (96.6%) were treated according to the TLICS guidelines. Conservative treatment failed for 2 of the 4 patients (1.7%) whose treatment did not correspond with TLICS, and they required surgical treatment. Of the 114 patients who underwent surgical treatment, in 87 (76.3%) the treatment corresponded to the TLICS guidelines. CONCLUSIONS: The TLICS classification showed high validity for the conservative treatment of thoracolumbar injuries.
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Humans , Classification , Retrospective Studies , Spinal Injuries , Spine , SurgeonsABSTRACT
Lumbar epidural block using a “loss of resistance” technique (LORT) with air can potentially cause pneumocephalus. Herein, we present a pneumocephalus that occurred after an epidural block. A 58-year-old male patient underwent an interlaminar lumbar epidural block using a LORT with air for L4–5 disc herniation. After the block, the patient complained of headache, vomiting, and truncal myoclonus. For further evaluation, a brain computed tomography was performed, and pneumocephalus was finally diagnosed. The patient underwent conservative treatment and recovered without any complications. He was discharged on the 11th day after the block.
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Humans , Male , Middle Aged , Brain , Headache , Injections, Epidural , Myoclonus , Pneumocephalus , VomitingABSTRACT
Anterior cervical fusion has become a standard of care for numerous pathologic conditions of the cervical spine. However, subsequent development of clinically significant disc disease at levels adjacent to fused discs is a serious long-term complication of this procedure. As more patients live longer after surgery, it is foreseeable that adjacent segment pathology (ASP) will develop in increasing numbers of patients. Also, ASP has been studied more intensively with the recent popularity of motion preservation technologies like total disc arthroplasty. The true nature and scope of ASP remains poorly understood. The etiology of ASP is most likely multifactorial. Various factors including altered biomechanical stresses, surgical disruption of soft tissue and the natural history of cervical disc disease contribute to the development of ASP. General factors associated with disc degeneration including gender, age, smoking and sports may play a role in the development of ASP. Postoperative sagittal alignment and type of surgery are also considered potential causes of ASP. Therefore, a spine surgeon must be particularly careful to avoid unnecessary disruption of the musculoligamentous structures, reduced risk of direct injury to the disc during dissection and maintain a safe margin between the plate edge and adjacent vertebrae during anterior cervical fusion.
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Humans , Intervertebral Disc Degeneration , Natural History , Pathology , Reoperation , Risk Factors , Smoke , Smoking , Spinal Fusion , Spine , Sports , Standard of Care , Total Disc Replacement , ViperidaeABSTRACT
STUDY DESIGN: Retrospective study. OBJECTIVES: To evaluate the clinical and radiological outcomes of posterior interbody fusion using pedicle screw fixation after posterior decompression for high-grade spondylolisthesis. SUMMARY OF LITERATURE REVIEW: The surgical treatment of high-grade spondylolisthesis has been controversial. However, few reports on the results of reduction and posterior interbody fusion after posterior decompression have been published. MATERIALS AND METHODS: Thirteen patients with L5-S1 high-grade spondylolisthesis (Meyerding grade III, IV) who underwent reduction and posterior interbody fusion were analyzed with at least 2 years of follow-up. The mean age of the patients (male 2, female 11) was 51 years. Classified by the type of spondylolisthesis, 10 cases were isthmic, 2 cases dysplastic, and 1 case degenerative. A visual analogue scale (VAS), the Oswestry Disability Index (ODI) score, bone union, anterior slippage, and slip angle were used in comparing clinical and radiographic outcomes. RESULTS: All cases showed improvement of preoperative symptoms. The VAS and ODI score improved from a mean of 8.9 points and 36.2 points preoperatively to 2.1 points and 10.2 points, respectively, at last follow-up. The degree of anterior slippage measured by Taillard's method was improved from a mean of 57.7% before surgery to mean of 14.6% at last follow-up. The slip angle also changed from a mean of 2.4° kyphosis before surgery to a mean of 7.6°C lordosis at last follow-up. There were two complications: infection and new radiating pain. CONCLUSIONS: Reduction and posterior interbody fusion using pedicle screw fixation after posterior decompression was a useful surgical method for high-grade spondylolisthesis that corrected lumbosacral kyphosis, filled the structural space of the anterior column, and acheived fusion of interbody movement.
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Animals , Female , Humans , Decompression , Follow-Up Studies , Kyphosis , Lordosis , Methods , Pedicle Screws , Retrospective Studies , SpondylolisthesisABSTRACT
Excessive spine operations is an economic and social problem today in Korea. Proper conservative treatment can reduce the need for surgical treatment by relieving the pain during the acute phase of spinal disease. Epidural steroid injection and a selective nerve root block are relatively safer and easier than other treatments. They may have many advantages such as relief of neck and back pain and of radicular pain, and reducing the gastrointestinal adverse effects caused by long-term NSAID medication or injection. Furthermore, patients in an inoperable state due to old age or other comorbidities and outpatients who want conservative treatment may benefit from epidural steroid injection and a nerve root block. The treatment outcomes differ among reports. The efficacy of temporary pain relief has been described to be excellent, but it gradually decreases as time passes. Recently, transforaminal epidural steroid injection has been widely performed. Epidural steroid injection should be performed for temporary pain relief due to its limited efficacy. In addition, an overuse of epidural and selective nerve root steroid injection can cause serious side effects. Therefore, this procedure should be done with caution, taking into account the technical risks and side effects.
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Humans , Back Pain , Comorbidity , Injections, Epidural , Korea , Neck , Nerve Block , Outpatients , Pain Management , Social Problems , Spinal Diseases , Spine , SteroidsABSTRACT
This article has been retracted.
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STUDY DESIGN: Retrospective study. OBJECTIVES: To investigate the outcomes of fluoroscopically guided selective nerve root block as a nonsurgical treatment for cervical radiculopathy. OVERVIEW OF LITERATURE: Only a few studies have addressed the efficacy and persistence of cervical nerve root block. METHODS: This retrospective study was conducted on 28 consecutive patients with radicular pain due to cervical disc disease or cervical spondylosis. Myelopathy was excluded. Cervical nerve root blocks were administered every 2 weeks, up to 3 times. Outcomes were measured by comparing visual analogue scale (VAS) scores, patient satisfaction, and medication usage before the procedure and at 1 week and 3, 6, and 12 months after the procedure. In addition, complications associated with the procedure and need for other treatments were evaluated. RESULTS: The average preoperative VAS score was 7.8 (range, 5 to 10), and this changed to 2.9 (range, 1 to 7) at 3 months and 4.6 (range, 2 to 7) at 12 months. Patient satisfaction was 71% at 3 months and 50% at 12 months. Five patients used medication at 3 months, whereas 13 used medication at 12 months. Average symptom free duration after the procedure was 7.8 months (range, 1 to 12 months). Two patients were treated surgically. Only two minor complications were noted; transient ptosis with Horner's syndrome and transient causalgia. CONCLUSIONS: Although selective nerve root block for cervical radiculopathy is limited as a definitive treatment, it appears to be useful in terms of providing relief from radicular pain in about 50% of patients at 12 months.
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Humans , Horner Syndrome , Nerve Block , Patient Satisfaction , Radiculopathy , Retrospective Studies , Spinal Cord Diseases , Spinal Nerve Roots , SpondylosisABSTRACT
STUDY DESIGN: Retrospective chart review. PURPOSE: To assess whether spontaneous reduction of spondylolisthesis, as seen on magnetic resonance imaging (MRI), is related to the degree of segmental instability and low back pain. OVERVIEW OF LITERATURE: The flexion-extension radiographs obtained in the sagittal plane are frequently used when segmental instability of spondylolisthesis is evaluated. METHODS: We retrospectively reviewed 137 patients and measured the differences of the percentage of sagittal translation and sagittal angulation to determine the segmental instability between the flexion and extension radiographs, and the spontaneous reduction on MRI. We then compared the degrees of segmental instability and the degrees of spontaneous reduction. To assess the effect of low back pain on segmental motion in regards to the flexion-extension radiographs, we compared the preoperative visual analogue scales (VAS) score for low back pain between the more and the less spontaneous reduction groups. RESULTS: The mean degree of spontaneous reduction was 5.2%. A statistically significant correlation was found between the sagittal translation on the flexion-extension radiographs and the degree of spontaneous reduction (r = 0.557, p < 0.001) and between the sagittal angulation on the flexion-extension radiographs and the degree of spontaneous reduction (r = 0.215, p = 0.012). The preoperative VAS scores for low back pain of the more spontaneous reduction group and the less spontaneous reduction group were 4.6 and 3.6 points, respectively, and this difference was statistically significant (p = 0.002). CONCLUSIONS: Spontaneous reduction of spondylolisthesis on MRI was found to be closely related to segmental instability, and the degree of spontaneous reduction seen on MRI could be useful for the evaluation of segmental instability in patients with spondylolisthesis, especially with severe low back pain.
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Humans , Low Back Pain , Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy , Magnetics , Magnets , Retrospective Studies , Spondylolisthesis , Weights and MeasuresABSTRACT
We investigated the influence of photon energy, couch and collimator angle differences between arcs on dose distribution of RapidArc treatment planning for prostate cancer. RapidArc plans were created for 6 MV and 10 MV photons using 2 arcs coplanar and noncoplanar fields. The collimator angle differences between two arcs were 0degrees, 15degrees, 30degrees, 45degrees, 60degrees, 75degrees and 90degrees. The plans were optimized using same dose constrains for target and OAR (organ at risk). To evaluate the dose distribution, plans were analyzed using CI (conformity index), HI (homogeneity index), QOC (quality of coverage), etc. Photon energy, couch and collimator angle differences between arcs had a little influence on the target and OAR. The difference of dosimetric indices was less than 3.6% in the target and OAR. However, there was significant increase in the region exposed to low dose. The increase of V15% in the femur was 6.4% (left) and 5.5% (right) for the 6 MV treatment plan and 23.4% (left), 24.1% (right) for the noncoplanar plan. The increase of V10% in the Far Region distant from target was 54.2 cc for the 6 MV photon energy, 343.4 cc for the noncoplanar and 457.8 cc for the no collimator rotation between arcs.
Subject(s)
Femur , Photons , Prostate , Prostatic NeoplasmsABSTRACT
The pencil beam convolution (PBC) algorithms in radiation treatment planning system have been widely used to calculate the radiation dose. A new photon dose calculation algorithm, referred to as the anisotropic analytical algorithm (AAA), was released for use by the Varian medical system. The aim of this paper was to investigate the difference in dose calculation between the AAA and PBC algorithm using the intensity modulated radiation therapy (IMRT) plan for lung cancer cases that were inhomogeneous in the low density. We quantitatively analyzed the differences in dose using the eclipse planning system (Varian Medical System, Palo Alto, CA) and I'mRT matirxx (IBA, Schwarzenbruck, Germany) equipment to compare the gamma evaluation. 11 patients with lung cancer at various sites were used in this study. We also used the TLD-100 (LiF) to measure the differences in dose between the calculated dose and measured dose in the Alderson Rando phantom. The maximum, mean, minimum dose for the normal tissue did not change significantly. But the volume of the PTV covered by the 95% isodose curve was decreased by 6% in the lung due to the difference in the algorithms. The difference dose between the calculated dose by the PBC algorithms and AAA algorithms and the measured dose with TLD-100 (LiF) in the Alderson Rando phantom was -4.6% and -2.7% respectively. Based on the results of this study, the treatment plan calculated using the AAA algorithms is more accurate in lung sites with a low density when compared to the treatment plan calculated using the PBC algorithms.
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Humans , Lung , Lung NeoplasmsABSTRACT
PURPOSE: This treatment planning study was undertaken to evaluate the impact of beam angle configuration of intensity-modulated radiotherapy (IMRT) on the dose of the normal liver in hepatocellular carcinoma (HCC). MATERIALS AND METHODS: The computed tomography datasets of 25 patients treated with IMRT for HCC were selected. Two IMRT plans using five beams were made in each patient; beams with equidistance of 72degrees (Plan I), and beams with a 30degrees angle of separation entering the body near the tumor (Plan II). Both plans were generated using the same constraints in each patient. Conformity index (CI), homogeneity index (HI), gamma index, mean dose of the normal liver (Dmean_NL), Dmean_NL difference between the two plans, and percentage normal liver volumes receiving at least 10, 20, and 30 Gy (V10, V20, and V30) were evaluated and compared. RESULTS: Dmean_NL, V10, and V20 were significantly better for Plan II. The Dmean_NL was significantly lower for peripheral (p = 0.001) and central tumors (p = 0.034). Dmean_NL differences between the two plans increased in proportion to gross tumor volume to normal liver volume ratios (p = 0.002). CI, HI, and gamma indices were not significantly different for the two plans. CONCLUSION: The IMRT plan based on beams with narrow separations reduced the irradiated dose of the normal liver, which would allow radiation dose escalation for HCC.
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Humans , Carcinoma, Hepatocellular , Liver , Radiotherapy, Intensity-Modulated , Tumor BurdenABSTRACT
OBJECTIVE: To study the clinical significance and relevant factors of radiation-induced intratumoral necrosis (RIN) and peritumoral edema (PTE) after Gamma knife radiosurgery (GKRS) for intracranial meningiomas. METHODS: We retrospectively analyzed the data of 64 patients who underwent GKRS for intracranial meningioma. The mean lesion volume was 4.9 cc (range, 0.3-20), and the mean prescription dose of 13.4 Gy (range, 11-18) was delivered to the mean 49.9% (range, 45-50) isodose line. RIN was defined as newly developed or enlarged intratumoral necrosis after GKRS. RESULTS: RIN and new development or aggravation of PTE were observed in 21 (32.8%) and 18 (28.1%) cases of meningioma, respectively during the median follow-up duration of 19.9+/-1.0 months. Among various factors, maximum dose (>25 Gy) and target volume (>4.5 cc) were significantly related to RIN, and RIN and maximum dose (>24 Gy) were significantly related to the development or aggravation of PTE. In 21 meningiomas with development of RIN after GKRS, there was no significant change of the tumor volume itself between the times of GKRS and RIN. However, the PTE volume increased significantly compared to that at the time of GKRS (p=0.013). The median interval to RIN after GKRS was 6.5+/-0.4 months and the median interval to new or aggravated PTE was 7.0+/-0.7 months. CONCLUSION: A close observation is required for meningiomas treated with a maximum dose >24 Gy and showing RIN after GKRS, since following or accompanying PTE may deteriorate neurological conditions especially when the location involves adjacent critical structures.
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Humans , Edema , Follow-Up Studies , Meningioma , Necrosis , Prescriptions , Radiosurgery , Retrospective Studies , Tumor BurdenABSTRACT
The energy spectra for electron beam of medical linear accelerator were calculated using a GEANT4 Medical Linac 2 example code. The incident electron mean energy were 6, 9, 12, 16, 20 MeV. This code was designed to calculate electron beam energy spectra according to material, thickness and location of electron scattering foil affecting electron beam characteristic. Lead, Copper, Aluminum and Gold were used for scattering foil. The energy distribution for electron and photon were analyzed by changing position of scattering foil in the head of linear accelerator. The effect of electron scattering foil on energy spectra which is basic data of simulation for medical linear accelerator were presented. The calculated results would be used in design of medical accelerator head.