• Title/Summary/Keyword: 방사선 위험성 평가

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Utility Evaluation of Supportive Devices for Interventional Lower Extremity Angiography (인터벤션 하지 혈관조영검사를 위한 보조기구의 유용성 평가)

  • Kong, Chang gi;Song, Jong Nam;Jeong, Moon Taek;Han, Jae Bok
    • Journal of the Korean Society of Radiology
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    • v.13 no.4
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    • pp.613-621
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    • 2019
  • The purpose of this study is to evaluate the effectiveness of supportive devices which are for minimizing the patient's movement during lower extremity angiography and to verify image quality of phantom by analyzing of Mask image, DSA image and Roadmap image into SNR and CNR. As a result of comparing SNR with CNR of mask image obtained by DSA technique using the phantom alone and phantom placed on the supportive devices, there was no significant difference between about 0~0.06 for SNR and about 0~0.003 for CNR. The study showed about 0.11~0.35 for SNR and 0.016~0.031 for CNR of DSA imaging by DSA technique about only water phantom of the blood vessel model and the water phantom placed on the device. Analyzing SNR and CNR of Roadmap technique about water phantom on the auxiliary device (hardboard paper, pomax, polycarbonate, acrylic) and water phantom alone, there was no significant difference between 0.02~0.05 for SNR and 0.002~0.004 for CNR. In conclusion, there was no significant difference on image quality by using supportive devices made by hardboard paper, pomax, polycarbonate or acryl regardless of whether using supportive devices or not. Supportive devices to minimize of the patient's movement may reduce the total amount of contrast, exam-time, radiation exposure and eliminate risk factors during angiogram. Supportive devices made by hardboard paper can be applied easily during angiogram due to advantages of reasonable price and simple processing. It is considered that will be useful to consider cost efficiency and types of materials and their properties in accordance with purpose and method of the study when the operator makes and uses supportive devices.

Potential Risk Assessment of Cardiovascular Disease in Low Calcium-Score (낮은 칼슘 수치에서 심혈관질환의 잠재 위험도 평가)

  • Yoo, Heangsoo;Park, Jikoon;Jung, Bongjae;Noh, Sicheol;Choi, IlhHong;Jung, Hyungjn;Kang, Sangsik
    • Journal of the Korean Society of Radiology
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    • v.7 no.6
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    • pp.369-376
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    • 2013
  • Prepared her for the early detection of the risk of cardiovascular disease prevention for the various attempts being made ill through a lot of research to the criteria of coronary artery calcification, but the figure is more than 100 the progress of the flow can be expected to be was. In this study, we quantify the correlation between body composition analysis, blood lipid levels of calcium and public asymptomatic even at low calcium levels in comparison with the existing studies by analyzing potential risk of cardiovascular disease will be represented on the were evaluated. Studies, the calcium scores in the body composition analysis "1-10", and when "11-100" when there was a significant correlation in BMI and WHR look more normal frequency range of the mean values in the normal range meomulreoteuna 21% relative HDL and TG in lipid profiles, no significant correlation look more normal frequency range of risk were derived from the mean values in the normal range, 21% to 40% of the relative risk were derived. meomulreoteuna. In addition, there is no correlation between BFM and BMR Also, average increases in the frequency of a higher standard was higher relative risk derived 31 to 93%, and geological correlation test TC above 20mg/dl atherosclerotic sclerosis seems to be the value of HDL to act to remove cholesterol from atheroma already looking at the same time to suppress the occurrence of atherosclerosis, increased LDL showed higher values occurs rapidly increasing. At this time, the relative risk of 43-50% have been identified. In other words, even when calcium levels are low, that is inherent in the incidence of cardiovascular disease was unknown.

Difference in the Set-up Margin between 2D Conventional and 3D CT Based Planning in Patients with Early Breast Cancer (조기유방암환자의 이차원치료계획과 삼차원치료계획의 방사선조사범위의 차이)

  • Jo, Sun-Mi;Chun, Mi-Son;Kim, Mi-Hwa;Oh, Young-Taek;Kang, Seung-Hee;Noh, O-Kyu
    • Radiation Oncology Journal
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    • v.28 no.3
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    • pp.177-183
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    • 2010
  • Purpose: Simulation using computed tomography (CT) is now widely available for radiation treatment planning for breast cancer. It is an important tool to help define the tumor target and normal tissue based on anatomical features of an individual patient. In Korea, most patients have small sized breasts and the purpose of this study was to review the margin of treatment field between conventional two-dimensional (2D) planning and CT based three-dimensional (3D) planning in patients with small breasts. Materials and Methods: Twenty-five consecutive patients with early breast cancer undergoing breast conservation therapy were selected. All patients underwent 3D CT based planning with a conventional breast tangential field design. In 2D planning, the treatment field margins were determined by palpation of the breast parenchyma (In general, the superior: base of the clavicle, medial: midline, lateral: mid - axillary line, and inferior margin: 2 m below the inframammary fold). In 3D planning, the clinical target volume (CTV) ought to comprise all glandular breast tissue, and the PTV was obtained by adding a 3D margin of 1 cm around the CTV except in the skin direction. The difference in the treatment field margin and equivalent field size between 2D and 3D planning were evaluated. The association between radiation field margins and factors such as body mass index, menopause status, and bra size was determined. Lung volume and heart volume were examined on the basis of the prescribed breast radiation dose and 3D dose distribution. Results: The margins of the treatment field were smaller in the 3D planning except for two patients. The superior margin was especially variable (average, 2.5 cm; range, -2.5 to 4.5 cm; SD, 1.85). The margin of these targets did not vary equally across BMI class, menopause status, or bra size. The average irradiated lung volume was significantly lower for 3D planning. The average irradiated heart volume did not decrease significantly. Conclusion: The use of 3D CT based planning reduced the radiation field in early breast cancer patients with small breasts in relation to conventional planning. Though a coherent definition of the breast is needed, CT-based planning generated the better plan in terms of reducing the irradiation volume of normal tissue. Moreover it was possible that 3D CT based planning showed better CTV coverage including postoperative change.

Evaluation of Clinical Availability for Shoulder Forced Traction Method to Minimize the Beam Hardening Artifact in Cervical-spine Computed Tomography (CT) (경추부 전산화단층촬영에서 선속 경화 인공물을 최소화하기 위한 견부 강제 견인법에 대한 임상적 유용성 평가)

  • Kim, Moonjeung;Cho, Wonjin;Kang, Suyeon;Lee, Wonseok;Park, Jinwoo;Yu, Yunsik;Im, Inchul;Lee, Jaeseung;Kim, Hyeonjin;Kwak, Byungjoon
    • Journal of the Korean Society of Radiology
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    • v.7 no.1
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    • pp.37-44
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    • 2013
  • In study suggested clinical availability to shoulder forced traction method in term of quality of image, the patient's convenience and stability, according to whether to use of shoulder forced traction bend using computed tomography(CT) that X-ray calibration and various mathematic calibration algorithm application can be applied by AEC. To achieve this, 79 patients is complaining of cervical pain oriented that shoulder forced traction bend use the before and after acquires lateral projection scout image and transverse image. transverse image of a fixed size in concern field of pixel and figure the average HU value compare that quantitative analysis. Artifact and pixel and resolution to qualitative clinical estimation image analysis. the patient feel inconvenience degree that self-diagnosis survey that estimate. As a result, lateral projection scout image if you used shoulder forced traction bend for the depicted has been an increase in the number of a cervical vertebrae. transverse image concern field shoulder forced traction bend use the before and after for pixel and the average HU-value changes was judged to be almost irrelevant. Artifact and resolution and contrast, in qualitative analysis of the results relating the observer to the unusual result. So, the patients of 82.27% complained discomfort that use of shoulder forced traction bend in self-diagnosis survey. No merit of medical image by using of bend from result was analyzed quality of image to quantitative and qualitative method judged. Nowadays, CT is supplied possible revision of quality of radiation by reduction of slice and automatic exposure controller, etc and application of preconditioning filter process due to various mathematic revision algorithm. So, image noise by beam hardening artifact should not be a problem. shoulder forced traction bend of use no longer judged clinically availability because have not influence of image quality and give discomfort, have extra dangerousness.

Analyzation of Correlation between Clinical Factors and Carotid Ultrasonography Diagnosis (경동맥 초음파진단과 관련된 임상변수에 대한 분석)

  • Cho, Jin-Young;Ye, Soo-Young
    • Journal of the Korean Society of Radiology
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    • v.14 no.5
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    • pp.705-713
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    • 2020
  • Arteriosclerosis is a disease in which blood circulation is impaired due to loss of elasticity as blood vessels become narrower, and is a potential cause of recently increasing cardiovascular and cerebrovascular diseases. Carotid ultrasound is used as a predictor of cardiovascular and cerebrovascular diseases by evaluating the degree of atherosclerosis. Therefore, this paper attempted to investigate the correlation between the increase in the thickness of the inner media and various clinical variables in carotid ultrasound. Patients with carotid ultrasound findings were classified into three stages: mild intima thickening, sclerosis, and significant stenosis. CAVI (Carotid Ankle Vascular Index: vascular age) data measured in the degree and physical characteristics of the carotid artery(gender, age, body mass index, blood pressure), blood test(total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, creatine phosphokinase, fasting blood sugar), and arteriosclerosis test were collected. It was confirmed that the carotid intima thickness was correlated with variables such as hypertension, hyperlipidemia, and BMI, and also correlated with the risk factors of cardiovascular disease as CAVI increased.

Effectiveness Assessment on Jaw-Tracking in Intensity Modulated Radiation Therapy and Volumetric Modulated Arc Therapy for Esophageal Cancer (식도암 세기조절방사선치료와 용적세기조절회전치료에 대한 Jaw-Tracking의 유용성 평가)

  • Oh, Hyeon Taek;Yoo, Soon Mi;Jeon, Soo Dong;Kim, Min Su;Song, Heung Kwon;Yoon, In Ha;Back, Geum Mun
    • The Journal of Korean Society for Radiation Therapy
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    • v.31 no.1
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    • pp.33-41
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    • 2019
  • Purpose : To evaluate the effectiveness of Jaw-tracking(JT) technique in Intensity-modulated radiation therapy(IMRT) and Volumetric-modulated arc therapy(VMAT) for radiation therapy of esophageal cancer by analyzing volume dose of perimetrical normal organs along with the low-dose volume regions. Materials and Method: A total of 27 patients were selected who received radiation therapy for esophageal cancer with using $VitalBeam^{TM}$(Varian Medical System, U.S.A) in our hospital. Using Eclipse system(Ver. 13.6 Varian, U.S.A), radiation treatment planning was set up with Jaw-tracking technique(JT) and Non-Jaw-tracking technique(NJT), and was conducted for the patients with T-shaped Planning target volume(PTV), including Supraclavicular lymph nodes(SCL). PTV was classified into whether celiac area was included or not to identify the influence on the radiation field. To compare the treatment plans, Organ at risk(OAR) was defined to bilateral lung, heart, and spinal cord and evaluated for Conformity index(CI) and Homogeneity index(HI). Portal dosimetry was performed to verify a clinical application using Electronic portal imaging device(EPID) and Gamma analysis was performed with establishing thresholds of radiation field as a parameter, with various range of 0 %, 5 %, and 10 %. Results: All treatment plans were established on gamma pass rates of 95 % with 3 mm/3 % criteria. For a threshold of 10 %, both JT and NJT passed with rate of more than 95 % and both gamma passing rate decreased more than 1 % in IMRT as the low dose threshold decreased to 5 % and 0 %. For the case of JT in IMRT on PTV without celiac area, $V_5$ and $V_{10}$ of both lung showed a decrease by respectively 8.5 % and 5.3 % in average and up to 14.7 %. A $D_{mean}$ decreased by $72.3{\pm}51cGy$, while there was an increase in radiation dose reduction in PTV including celiac area. A $D_{mean}$ of heart decreased by $68.9{\pm}38.5cGy$ and that of spinal cord decreased by $39.7{\pm}30cGy$. For the case of JT in VMAT, $V_5$ decreased by 2.5 % in average in lungs, and also a little amount in heart and spinal cord. Radiation dose reduction of JT showed an increase when PTV includes celiac area in VMAT. Conclusion: In the radiation treatment planning for esophageal cancer, IMRT showed a significant decrease in $V_5$, and $V_{10}$ of both lungs when applying JT, and dose reduction was greater when the irradiated area in low-dose field is larger. Therefore, IMRT is more advantageous in applying JT than VMAT for radiation therapy of esophageal cancer and can protect the normal organs from MLC leakage and transmitted doses in low-dose field.

The Necessity of Early Adjuvant Radiotherapy for Better Outcomes in the Treatment of a Desmoid Tumor (데스모이드 종양에 대한 조기 방사선치료의 필요성)

  • Lee, Me-Yeon;Chang, Ah-Ram;Kim, Hak-Jae;Kim, Kyu-Bo;Kim, Jin-Ho;Park, Charn-Il;Ha, Sung-Whan;Wu, Hong-Gyun;Kim, Il-Han
    • Radiation Oncology Journal
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    • v.25 no.4
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    • pp.201-205
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    • 2007
  • Purpose: This retrospective study was conducted to assess outcome and to determine the prognostic factors in patients with a desmoid tumor treated with postoperative radiotherapy. Materials and Methods: Twenty-seven patients with a desmoid tumor who were treated with postoperative radiotherapy between June 1984 and October 2005 were analyzed. There were 13 male and 14 female patients. The age of the patients ranged from 3 to 79 years (median age, 28 years). Tumors were located in an extra-abdominal area (21 cases), and in the abdominal walls (6 cases). The tumor size ranged from 2.5 to 25 cm (median size, 7.5 cm) in the largest linear dimension. Thirteen cases received radiotherapy after initial surgery, and 14 recurrent cases received radiotherapy after additional surgery. The total radiation dose given was $45{\sim}66$ Gy (median dose, 59.4 Gy), and the fraction size was $1.8{\sim}2.0$ Gy. Results: The median follow-up period was 61 months (range, $12{\sim}203$ months). Two patients developed local progression and six patients experienced local recurrence. The 5-year disease-free survival rate and the 5-year progression-free survival rate were 61 % and 70%, respectively. Wide local excision was associated with better disease free survival with statistical significance (p=0.028). Radiotherapy after initial surgery (p=0.046) and a higher radiation dose of more than 60 Gy (p=0.049) were associated with better progression free survival with statistical significance. At the time of the last follow-up, the number of additional surgeries was higher in patients that received radiotherapy after reoperation (p<0.001). Conclusion: Radiotherapy after the initial operation improved local control and decreased the number of subsequent operations. Thus, postoperative radiotherapy after an initial operation is recommended in patients with a high risk of recurrence for a desmoid tumor.

Cu Electroplating on the Si Wafer and Reliability Assessment of Low Alpha Solder Bump for 3-D Packaging (3차원 실장용 실리콘 웨이퍼 Cu 전해도금 및 로우알파솔더 범프의 신뢰성 평가)

  • Jung, Do Hyun;Lee, Joon Hyung;Jung, Jae Pil
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2012.11a
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    • pp.123-123
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    • 2012
  • 최근 연구되고 있는 TSV(Through Silicon Via) 기술은 Si 웨이퍼 상에 직접 전기적 연결 통로인 관통홀을 형성하는 방법으로 칩간 연결거리를 최소화 할 수 있으며, 부피의 감소, 연결부 단축에 따른 빠른 신호 전달을 가능하게 한다. 이러한 TSV 기술은 최근의 초경량화와 고집적화로 대표되는 전자제품의 요구를 만족시킬 수 있는 차세대 실장법으로 기대를 모으고 있다. 한편, 납땜 재료의 주 원료인 주석은 주로 반도체 소자의 제조, 반도체 칩과 기판의 접합 및 플립 칩 (Flip Chip) 제조시의 범프 형성 등 반도체용 배선재료에 널리 사용되고 있다. 최근에는 납의 유해성 때문에 대부분의 전자제품은 무연솔더를 이용하여 제조되고 있지만, 주석을 이용한 반도체 소자가 고밀도화, 고 용량화 및 미세피치(Fine Pitch)화 되고 있기 때문에, 반도체 칩의 근방에 배치된 주석으로부터 많은 알파 방사선이 방출되어 메모리 셀의 정보를 유실시키는 소프트 에러 (Soft Error)가 발생되는 위험이 많아지고 있다. 이로 인해, 반도체 소자 및 납땜 재료의 주 원료인 주석의 고순도화가 요구되고 있으며, 특히 알파 방사선의 방출이 낮은 로우알파솔더 (Low Alpha Solder)가 요구되고 있다. 이에 따라 본 연구는 4인치 실리콘 웨이퍼상에 직경 $60{\mu}m$, 깊이 $120{\mu}m$의 비아홀을 형성하고, 비아 홀 내에 기능 박막증착 및 전해도금을 이용하여 전도성 물질인 Cu를 충전한 후 직경 $80{\mu}m$의 로우알파 Sn-1.0Ag-0.5Cu 솔더를 접합 한 후, 접합부 신뢰성 평가를 수행을 위해 고속 전단시험을 실시하였다. 비아 홀 내 미세구조와 범프의 형상 및 전단시험 후 파괴모드의 분석은 FE-SEM (Field Emission Scanning Electron Microscope)을 이용하여 관찰하였다. 연구 결과 비아의 입구 막힘이나 보이드(Void)와 같은 결함 없이 Cu를 충전하였으며, 고속전단의 경우는 전단 속도가 증가할수록 취성파괴가 증가하는 경향을 보였다. 본 연구를 통하여 전해도금을 이용한 비아 홀 내 Cu의 고속 충전 및 로우알파 솔더 볼의 범프 형성이 가능하였으며, 이로 인한 전자제품의 소프트에러의 감소가 기대된다.

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A Prospective Randomized Comparative Clinical Trial Comparing the Efficacy between Ondansetron and Metoclopramide for Prevention of Nausea and Vomiting in Patients Undergoing Fractionated Radiotherapy to the Abdominal Region (복부 방사선치료를 받는 환자에서 발생하는 오심 및 구토에 대한 온단세트론과 메토클로프라미드의 효과 : 제 3상 전향적 무작위 비교임상시험)

  • Park Hee Chul;Suh Chang Ok;Seong Jinsil;Cho Jae Ho;Lim John Jihoon;Park Won;Song Jae Seok;Kim Gwi Eon
    • Radiation Oncology Journal
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    • v.19 no.2
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    • pp.127-135
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    • 2001
  • Purpose : This study is a prospective randomized clinical trial comparing the efficacy and complication of anti-emetic drugs for prevention of nausea and vomiting after radiotherapy which has moderate emetogenic potential. The aim of this study was to investigate whether the anti-emetic efficacy of ondansetron $(Zofran^{\circledR})$ 8 mg bid dose (Group O) is better than the efficacy of metoclopramide 5 mg lid dose (Group M) in patients undergoing fractionated radiotherapy to the abdominal region. Materials and Methods : Study entry was restricted to those patients who met the following eligibility criteria: histologically confirmed malignant disease; no distant metastasis; performance status of not more than ECOG grade 2; no previous chemotherapy and radiotherapy. Between March 1997 and February 1998, 60 patients enrolled in this study. All patients signed a written statement of informed consent prior to enrollment. Blinding was maintained by dosing identical number of tablets including one dose of matching placebo for Group O. The extent of nausea, appetite loss, and the number of emetic episodes were recorded everyday using diary card. The mean score of nausea, appetite loss and the mean number of emetic episodes were obtained in a weekly interval. Results : Prescription error occurred in one patient. And diary cards have not returned in 3 patients due to premature refusal of treatment. Card from one patient was excluded from the analysis because she had a history of treatment for neurosis. As a result, the analysis consisted of 55 patients. Patient characteristics and radiotherapy characteristics were similar except mean age was $52.9{\pm}11.2$ in group M, $46.5{\pm}9.5$ in group O. The difference of age was statistically significant. The mean score of nausea, appetite loss and emetic episodes in a weekly interval was higher in group M than O. In group M, the symptoms were most significant at 5th week. In a panel data analysis using mixed procedure, treatment group was only significant factor detecting the difference of weekly score for all three symptoms. Ondansetron $(Zofran^{\circledR})$ 8 mg bid dose and metoclopramide 5 mg lid dose were well tolerated without significant side effects. There were no clinically important changes In vital signs or clinical laboratory parameters with either drug. Conclusion : Concerning the fact that patients with younger age have higher emetogenic potential, there are possibilities that age difference between two treatment groups lowered the statistical power of analysis. There were significant difference favoring ondansetron group with respect to the severity of nausea, vomiting and loss of appetite. We concluded that ondansetron is more effective anti-emetic agents in the control of radiotherapy-induced nausea, vomiting, loss of appetite without significant toxicity, compared with commonly used drug, i.e., metoclopramide. However, there were patients suffering emesis despite the administration of ondansetron. The possible strategies to improve the prevention and the treatment of radiotherapy-induced emesis must be further studied.

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Comparisons of Unicortical and Bicortical Lateral Mass Screws in the Cervical Spine : Safety vs Strength (경추부의 후관절 나사못 고정술에서 단피질삽입법과 양피질 삽입법 간의 특성에 관한 비교)

  • Park, Choon-Keun;Hwang, Jang-Hoe;Ji, Chul;Lee, Jae Un;Sung, Jae Hoon;Choi, Seung-Jin;Lee, Sang-Won;Seybold, Eric;Park, Sung-Chan;Cho, Kyung-Suok;Park, Chun-Kun;Kang, Joon-Ki
    • Journal of Korean Neurosurgical Society
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    • v.30 no.10
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    • pp.1210-1219
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    • 2001
  • Introduction : The purpose of this study was to analyze the safety, pullout strength and radiographic characteristics of unicortical and bicortical screws of cervical facet within cadaveric specimens and evaluate the influence of level of training on the positioning of these screws. Methods : Twenty-one cadavers, mean 78.9 years of age, underwent bilateral placement of 3.5mm AO lateral mass screw from C3-C6(n=168) using a slight variation of the Magerl technique. Intraoperative imaging was not used. The right side(unicortical) utilized only 14mm screws(effective length of 11mm) while on the left side to determine the length of the screw after the ventral cortex had been drilled. Three spine surgeons(attending, fellow, chief resident) with varying levels of spine training performed the procedure on seven cadavers each. All spines were harvested and lateral radiographs were taken. Individual cervical vertebrae were carefully dissected and then axial radiographs were taken. The screws were evaluated clinically and radiographically for their safety. Screws were graded clinically for their safety with respect to the spinal cord, facet joint, nerve root and vertebral artery. The grades consisted of the following categories : "satisfactory", "at risk" and "direct injury". Each screw was also graded according to its zone placement. Screw position was quantified by measuring a sagittal angle from the lateral radiograph and an axial angle from the axial radiograph. Pull-out force was determined for all screws using a material testing machine. Results : Dissection revealed that fifteen screws on the left side actually had only unicortical and not bicortical purchase as intended. The majority of screws(92.8%) were satisfactory in terms of safety. There were no injuries to the spinal cord. On the right side(unicortical), 98.9% of the screws were "satisfactory" and on the left side(bicortical) 68.1% were "satisfactory". There was a 5.8% incidence of direct arterial injury and a 17.4% incidence of direct nerve root injury with the bicortical screws. There were no "direct injuries" with the unicortical screws for the nerve root or vertebral artery. The unicortical screws had a 21.4% incidence of direct injury of the facet joint, while the bicortical screws had a 21.7% incidence. The majority of "direct injury" of bicortical screws were placed by the surgeon with the least experience. The performance of the resident surgeon was significantly different from the attending or fellow(p<0.05) in terms of safety of the nerve root and vertebral artery. The attending's performance was significantly better than the resident or fellow(p<0.05) in terms of safety of the facet joint. There was no relationship between the safety of a screw and its zone placement. The axial deviation angle measured $23.5{\pm}6.6$ degrees and $19.8{\pm}7.9$ degrees for the unicortical and bicortical screws, respectively. The resident surgeon had a significantly lower angle than the attending or fellow(p<0.05). The sagittal angle measured $66.3{\pm}7.0$ degrees and $62.3{\pm}7.9$ degrees for the unicortical and bicortical screws, respectively. The attending had a significantly lower sagittal angle than the fellow or resident(p<0.05). Thirty-three screws that entered the facet joint were tested for pull-out strength but excluded from the data because they were not lateral mass screws per-se and had deviated substantially from the intended final trajectory. The mean pull-out force for all screws was $542.9{\pm}296.6N$. There was no statistically significant difference between the pull-out force for unicortical($519.9{\pm}286.9N$) and bicortical($565.2{\pm}306N$) screws. There was no significant difference in pull-out strengths with respect to zone placement. Conclusion : It is our belief that the risk associated with bicortical purchase mandates formal spine training if it is to be done safely and accurately. Unicortical screws are safer regardless of level of training. It is apparent that 14mm lateral mass screws placed in a supero-lateral trajectory in the adult cervical spine provide an equivalent strength with a much lower risk of injury than the longer bicortical screws placed in a similar orientation.

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