PURPOSE: We designed the aft-multiple-slit (AMS) system to reduce scatter in cone-beam computed tomography (CBCT). As a preliminary study, we performed a Monte Carlo N-Particle Transport Code (MCNP) simulation to verify the effectiveness of this system. MATERIALS AND METHODS: The MCNPX code was used to build the AMS geometry. An AMS is an equi-angled arc to consider beam divergence. The scatter-reduced projection images were compared with the primary images only and the primary plus scatter radiation images with and without AMS to evaluate the effectiveness of scatter reduction. To obtain the full 2 dimensional (2D) projection image, the whole AMS system was moved to obtain closed septa of the AMS after the first image acquisition. RESULTS: The primary radiation with and without AMS is identical to all the slit widths, but the profiles of the primary plus scattered radiation varied according to the slit widths in the 2D projection image. The average scatter reduction factors were 29%, 15%, 9%, and 8% when the slit widths were 5 mm, 10 mm, 15 mm, and 20 mm, respectively. CONCLUSION: We have evaluated the scatter reduction effect of the AMS in CBCT imaging using the Monte Carlo (MC) simulations. A preliminary study based on the MCNP simulations showed a mount of scatter reduction with the proposed system.
Cone-Beam Computed Tomography

OBJECTIVE: Using the standardization of disease diagnosis of disease, and surgical procedures, the authors have made a clinical application for the analysis of inpatient data with the ability to search for information pertinent for writing of clinical articles. METHODS: A client-server system and database software was developed for networking. For clinical application, a computerized daily report has been developed. Data from Neurosurgical patients admitted at Soonchunyang University Hospital from January to December 1998 were analyzed with this system. Data for clinical articles was obtained using the search mode, information such as orbital infarction syndrome following intracranial aneurysm surgery and epidemiological analysis or geriatric neurosurgical patients. RESULTS: For the daily report it takes approximately 10 minutes to input the patients demographic information, name of disease, diagnosis and surgical procedure. The daily report also numbers and sorts the inpatients according to large categories of diagnosis, reports the ratio between inpatients and operative patients. The annual report that was obtained was very accurate and gave rapid statistics for the one year. By retrospective study for the past 18 years, we calculated the incidence of orbital infarction syndrome following intracranial aneurysm surgery as 1.4%, and also estimated the population of geriatric inpatients as 18.3% by retrospective study. CONCLUSIONS: It has been found to be most useful to make a daily and annual report for tracking and research purposes. For use in clinical articles, it can be possible to do a search of the patients using the standardized disease, diagnosis and neurosurgical procedures application and obtain pertinent information in a timely manner.
Diagnosis ; Epidemiology* ; Humans ; Incidence ; Infarction ; Inpatients ; Intracranial Aneurysm ; Neurosurgical Procedures* ; Orbit ; Retrospective Studies ; Writing

OBJECTIVE: The the international classification of disease and surgical procedure has been found to be a lengthy and time-consuming text for use by neurosurgeons. A more subject matter related classification system is needed for use by this specialty. The author has developed a more comprehensive and standardized classification system specified for diagnosis of neurological disease and neurosurgical procedures. METHODS: Standardization of disease was completed by modifying the name of disease according to that which was used for daily report past 10 years, and from textbook of neurosurgery. The fields of international coding are continued in each. Neurosurgical procedures were designated and modified according to Current Procedure Terminology 96. Client-server system will be used for networking and database software applications have been developed. RESULTS: Disease was classified in 14 large categories and 379 subcategories. Diagnosis was classified in 12 large categories and 43 subcategories. Neurosurgical procedure has 20 large and 202 subcategories. The international coding system such as ICD-10 and ICD-9CM is maintained for the diagnosis and procedures to each category. CONCLUSIONS: It could be possible to make and use a standardized database model of disease, diagnosis and neurosurgical procedures to be used by physician.
Classification ; Clinical Coding ; Diagnosis ; Epidemiology* ; International Classification of Diseases ; Neurosurgery ; Neurosurgical Procedures*

No abstract available.
Prognosis* ; Subarachnoid Hemorrhage, Traumatic*

To investigate the causes of death in patients with spontaneous subarachnoid hemorrhage, 460 consecutive patients with a subarachnoid hemorrhage were reviewed. Angiography was not performed in 78 patients due to poor clinical conditions or discharge against admission. Of all these patients, 54(69.2%) died, 28 from serious clinical condition, 21 from rebleeding, 3 from pulmonary complications. 1 from vasospasm, and 1 with unknown causes. Thirty-eight patients were angiographically negative, of which 6(15.8%) died, 3 due to rebleeding, 2 due to poor clinical condition, and 1 due to cerebral infarction caused by vasospasm. Of the 344 patients who had an aneurysmal subarachnoid hemorrhage. 74 were discharged against admission or died before the surgery. The remaining 270 patients underwent aneurysm clipping. Early surgery(within 72 hours after subarachnoid hemorrhage) was performed in 151 patients, intermediate surgery (between Day 4 and 7 post SAH) in 74, and late surgery(Day 8 or later after SAH) in 45. Fifty-one patients (18.9%) died after aneurysm clipping. The remaining 270 patients underwent aneurysm clipping. Early surgery(within 72 hours after subarachnoid hemorrhage) was performed in 151 patients, intermediate surgery(between Day 4 and 7 post-SAH) in 74, and late surgery(Day 8 or later after SAH) in 45, Fifty-one patients(18.9%) died after aneurysm clipping. The causes were vasospasm in 17, complications related to surgery in 13, poor clinical condition in 12, preoperative rebleeding in 7, and other systemic condition in 2. A total of 59 patients suffered at least one rebleeding after the initial hemorrhage ; these patients had a mortality rate of 76.3% and the highest rate of rebleeding occurred within the first 24 hours after initial hemorrhage. Vasospasm and rebleeding were the leading causes of mortality in addition to the initial bleeding. Predictors for mortality included poor clinical grade, early surgery in patients aged 60 years or more, and association with intracerebral hematoam, intraventricular hemorrhage, or subdural hematoma.
Aneurysm ; Angiography ; Cause of Death ; Cerebral Infarction ; Hematoma, Subdural ; Hemorrhage ; Humans ; Mortality* ; Subarachnoid Hemorrhage*

OBJECTIVE: Although posterior wiring techniques have been commonly used with good results in treating the traumatic atlantoaxial instabilities, screw fixation technique has been gaining popularity to secure atlantoaxial arthrodesis in recent years. The purpose of this study is to compare the surgical results of posterior arthrodesis for the traumatic atlantoaxial instability between these two methods. METHODS: Twenty patients underwent 21 procedures over a 6-year period with a mean follow-up of 23 months. The most common condition of traumatic atlantoaxial instability was dens fracture(15 patients) followed by transverse atlantal ligament injury(4 patients), and traumatic os odontoideum(2 patients). Thirteen posterior wiring and eight posterior screw fixations were performed. Among 13 wiring methods, nine Galli fusions, two occipito-cervical fusions, one Brooks fusion, and one C1-C3 fusion were done. RESULTS: No patient developed neurological worsening after surgery. Compared to wire method, all patients of screw group had significant pain reduction when the patients was younger than 50 years old(p=0.01). The postoperative changes in distances of space available for cord(SAC) was not statistically significant between wire and screw methods(p=0.7). The rate of complication(23% in wire vs 25% in screw) was comparable to two methods. Although two screw malposition(25%) among screw fixations were developed, all revealed solid fusion without additional surgeries. The rate of fusion(85% in wire vs 100% in screw) was excellent in screw group. Postoperative loss of reduction, including redisplacement and kyphosis, was present only in wire group(31%). Two(15%) of wire fusions had redisplacement; both of these patients were type 2 dens fracture. Three procedures(23%) of wire fusions resulted in kyphotic change which occurred when delayed surgeries were done between 40 days and 90 days(mean: 63 days) after trauma. CONCLUSION: Considering both reduction loss and fusion rate, wire method caused more spinal deformity than screw method(38% vs 0%). This study demonstrates that screw method is a better surgical option for management of traumatic atlantoaxial instability.
Arthrodesis* ; Congenital Abnormalities ; Follow-Up Studies ; Humans ; Kyphosis ; Ligaments

In three(0.3%) of 1045 patients suffering from hypertensive intracerebral hematomas, two such hematomas occurred simultaneously. All three patients had a history of hypertension. The locations of the hematomas were as follows: Cerebellum and splenium of the corpus callosum in case 1, cerebellum and left thalamus in case 2, right thalamus and left frontoparietal lobe in case 3. One patient died of the ensuing hemorrhage and the other two remained moderate disability. Even though hypertension is considered to be a major factor of simultaneous occurrence of multiple intracerebral hematomas, their unusual locations suggest that a subtle degenerative process may be active in the pathogenesis of this condition.
Cerebellum ; Cerebral Hemorrhage* ; Corpus Callosum ; Hematoma ; Hemorrhage ; Humans ; Hypertension ; Thalamus

Delayed or enlarged lesions in head injury are potentially preventable events which worsen overall prognosis. We investigated the incidence and risk factors of these lesions in 240 head injured patients examined by repeated computerized tomographic(CT) scans from January 1989 to December 1990. Overall, delayed or enlarged lesions were found in 95 patients(39.6%) Intracerebral hemorrhage was the most common lesion(37 cases):Subdural(17 cases), epildural hematoma(16 cases), subdural hygroma(15 cases), cerebral swelling(6 cases), hydrocephalus(4 cases), and infarction(2 cases) followed in that order. These lesions occurred 3 days of initial scan in 64 patients(67.4%). Predictors were a low Glasgow Coma Scale score, abnormal papillary response, low or high blood pressure, hypoxia and previous infusion of large amounts of mannitol. Acute subdural hematoma was the most common initial lesion, heralding delayed or enlarged lesions in 50% of cases. Intracerebral hemtomas or contusion followed by next most common lesions. Incidence of delayed or enlarged lesions also differed according to therapy:decompressive craniectomy with these lesions in 82.8%. Mortality rate in patient who had delayed or enlarged lesions(35.5%) was 5.6 times higher than patient who did not have such lesions(6.3%). Delayed or enlarged lesions are relatively common. Patients with risk factors for delayed or enlarged lesions should be adequately monitored before overt clinical deterioration.
Anoxia ; Cerebral Hemorrhage ; Contusions ; Craniocerebral Trauma* ; Glasgow Coma Scale ; Head* ; Hematoma, Subdural, Acute ; Humans ; Hypertension ; Incidence ; Mannitol ; Mortality ; Prognosis ; Risk Factors*

A series of 89 patients diagnosed between 1988 and 1993 with computerized tomography(CT) as having subdural hematoma was studied retrospectively in order to evaluate the age of the subdural hematomas according to its appearance on CT scans. In all the patients, the interval from onset of injury to performance of CT scans was more than 2 days. The patients were divided into 4 groups based on the difference in density of the hematoma as seen on the CT scans;hyperdensity(16.9%), isodensity(30.3%), hypodensity(19.1%), and mixed-density(33.7%) groups. The mean interval from onset of injury to diagnosis in hyperdensity, hypodensity, mixed density, and isodensity groups was 15.7+/-18.3 days, 18.8+/-27.9 days, 35.6+/-62.1 days, and 47.6+/-52.1 days, respectively. The configuration of the hematomas on CT scans was crescentic in 74.2%, planoconvex in 12.4%, and biconvex in 13.5%. As the interval became longer, the hematomas tended to take on a planoconvex or biconvex shape rather than the crescentic shape;when the interval from onset of injury to diagnosis was within 7 days, crescentic shape was observed in 91%, within 8 to 21 days, 69%, and over 21 days, 58%. It is concluded from these findings that subdural hematomas undergo a progressive change in their attenuation as the hematomas age, changing from the initial hyperdense stage, go through a hypodense stage, and eventually to an isodense stage. These changes of attenuation values correlates fairly well with the rebleeding theory. The appearance of the hematomas as seen on CT scans also tended to change from the initial crescentic shape to the planoconvex or biconvex shape with time. However, given the possible variations of attenuation values and shapes of subdural hematomas, assumption of the age of the hematomas based on CT findings alone should be made with caution.
Diagnosis ; Hematoma ; Hematoma, Subdural* ; Hematoma, Subdural, Chronic ; Humans ; Retrospective Studies ; Tomography, X-Ray Computed

The purpose of this study is to identify a group of mild head injury patients having lesions on computerized tomography(CT) and to investigate the risk factors affecting the abnormal findings on CT scan. The study was limited to patients 16 years of age and older with a initial Glasgow Coma Scale(GCS) scores of at least 13 at the time of admission. Of a total of 243 patients studied, 156(64.2%) had abnormal CT findings. 49 patients(20.2%) required neurosurgical intervention(craniotomies for hematoma in 33, hematoma in 1 and subdural hygroma in 3). Four patients(2.4%) died of their cranial injury and three died of extracranial causes. The incidence of CT abnormalities for each GCS score was 86.7% in GCS of 13, 68.6% in GCS of 14, and 58.6% in GCS of 5. The factors affecting GCS scores at the time of admission were the presence of loss of consciousness and posttraumatic amnesia. The factors affecting abnormal CT scans were the presence of posttraumatic amnesia and skull fracture. A new lesion of extension of the initial finding on follow-up CT scans was found in 9.3% of 75 patients who underwent follow-up CT scans. Even though routine CT scans for mild head injury patients are not always necessary, these result suggest that all patients admitted to hospital after mild head injury should undergo CT scanning to enable early detection of an intracranial lesion.
Amnesia ; Coma ; Craniocerebral Trauma* ; Follow-Up Studies ; Glasgow Coma Scale ; Head* ; Hematoma ; Humans ; Incidence ; Risk Factors ; Skull Fractures ; Subdural Effusion ; Tomography, X-Ray Computed* ; Unconsciousness