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Monte Carlo validation in diagnostic radiological imaging

MEDICAL PHYSICS 2000年第6期27卷 1294-1304页

作者： Boone, JM Buonocore, MH Cooper, VN Univ Calif Davis Dept Radiol Sacramento CA 95817 USA

Monte Carlo analysis in the radiological sciences has been used for several decades, however with the ever-increasing power of desktop computers, the utility of Monte Carlo simulation is increasing. A Monte Carlo code called the Simple Investigative Environment for Radiological Research Applications (SIERRA) is described mathematically, and is then compared against an array of published and unpublished results determined by other means. A series of 32 comparisons between data sets, 22 from independent Monte Carlo simulations and 10 from physically measured data, were assessed. The compared parameters included depth dose curves, lateral energy scattering profiles, scatter to primary ratios, normalized glandular doses, angular scattering distributions, and computed tomography dose index (CTDI) values. Three of the 32 comparison data sets were excluded as they were identified as outliers. Of the remaining 29 data sets compared, the mean differences ranged from - 14.8% to + 17.2%, and the average of the mean differences was 0.12% (sigma=1.64%), and the median difference was 1.57%. Fifty percent of the comparisons showed mean differences of similar to 5% or less, and 93% of the comparisons showed mean differences of 12% or less. We conclude that for research applications in diagnostic radiology, the SIERRA Monte Carlo code demonstrates accuracy and precision to well within acceptable levels. (C) 2000 American Association of Physicists in Medicine. [S0094-2405(00)01506-6].

关键词：生物物理学计算机模拟数据说明统计蒙特卡罗法放射摄影术/统计学和数值数据软件人类

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Influence of postal distribution of The Royal College of Radiologists' guidelines, together with feedback on radiological referral rates, on X-ray referrals from general practice: a randomized controlled trial

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FAMILY PRACTICE 2000年第1期17卷 46-52页

作者： Kerry, S Oakeshott, P Dundas, D Williams, J Univ London St Georges Hosp Sch Med Dept Gen Practice & Primary Care London SW17 0RE England

Background. The Royal College of Radiologists (RCR) have produced regularly updated guidelines on radiological referrals since 1990. A small study in 1992 showed postal distribution of guidelines reduced general practitioners' referrals over the subsequent 9 weeks. However there have been no randomized trials of the longer term effects of radiological guidelines and feedback on referral rates on X-ray requests from primary care. Objectives. To see if the introduction of radiological guidelines into general practices together with feedback on referral rates reduces the number of GP radiological requests over one year;and to explore GPs' attitudes to the guidelines. Methods. Sixty-nine practices referring patients to St George's Healthcare Trust were randomly allocated to intervention or control groups. In February 1995 a GP version of the RCR guidelines was sent to each GP in the 33 practices in the intervention group. After 9 months intervention, practices were sent revised guidelines with individual feedback on the number of examinations requested in the past 6 months. The total number of requests per practice was compared for the year before and the year after the introduction of the guidelines. Control practices were sent the guidelines at the end of the study. All doctors were sent a questionnaire about the guidelines. Results. A total of 43 778 radiological requests were made during the two years 1994-1996. In practices receiving the guidelines there was a 20% reduction in requests for spinal examinations compared with control practices (P < 0.05). This corresponded to the effect reported by GPs. There was also a 10% difference between the groups in the total number of requests made, but due to wide interpractice variation in referral rates this failed to reach statistical significance. Conclusions. Introduction of radiological guidelines together with feedback on referral rates was effective in reducing the number of requests for spinal examinations over one y

关键词：医务工作者的态度置信区间家庭医学/统计学和数值数据反馈随访研究伦敦医师诊疗模式/统计学和数值数据邮政问卷调查放射摄影术/统计学和数值数据放射摄影术胸部/统计学和数值数据放射学转诊和会诊/统计学和数值数据脊柱/放射摄影术人类

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Stochastic risk estimate for barium radiological examinations in Malaga (Spain)

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PHYSICS IN MEDICINE AND BIOLOGY 2000年第1期45卷 241-252页

作者： Ruiz-Cruces, R Perez-Martinez, M Tort, I Ruiz, F Quesada, P de los Ríos, AD Univ Malaga Sch Med Radiol & Med Phys Dept Res Grp Radiat Protect E-29071 Malaga Spain

The aim of this research work has been the estimation of the stochastic risk for five barium examinations. The sample was the population attending the Radiological Service of the 'Nuestra Senora de la Victoria' University Hospital, who had been treated with some barium examinations, set in five different groups: oesophagus tract, oesophagus-gastric-duodenal tract, intestinal tract, enteroclysis and double enema. To estimate the stochastic risk, it is necessary to know the organ dose. This can be calculated from the dose-area product which allows us to determine the effective dose using software. The dose-ru ea product is the most suitable quantity to measure in these types of examination. We have evaluated the contribution that each procedure provides to the genetically significant dose, somatically significant dose, collective effective dose, annual effective dose 'per capita' and detriment, which are useful for assessing the population risk of cancer or hereditary effects after x-ray exposure. The contribution to the genetically significant dose is 6.7 mu Gy, to the somatically significant dose 8.82 mSv-yr, 16.07 person-Sv for the collective effective dose, 0.03 mSv for the 'per capita' annual effective dose and the annual aggregated detriment is 0.33.

关键词：年龄因素钡消化系统/诊断显像食管/诊断显像放射摄影术/统计学和数值数据危险因素西班牙随机过程女(雌)性人类男(雄)性中年人

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Routine radiography following ankle fracture fixation: a case for limiting its use

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INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED 1999年第10期30卷 699-701页

作者： Harish, S Vince, AS Patel, AD Norfolk & Norwich Hosp Dept Orthopaed Norwich NR1 3SR Norfolk England

The use of fluoroscopic screening in the orthopaedic theatre is a necessary operative aid in many procedures. Modern systems give good image resolution and allow the production of per-operative hard-copy prints. This study was performed to compare these prints with postoperative radiographs in 41 patients who underwent internal fixation for an ankle fracture in a 6-month period. The hard-copy prints and the postoperative X-ray films were independently assessed for several features, which included status of the tibiofibular syndesmosis, fibular length, talo-crural angle, talar tilt, presence and size of a posterior malleolar fracture, and abnormality of the medial clear space. Information was also recorded as to whether there had been a change in postoperative management plan after review of the check X-ray. Of the 41 cases, 30 were suitable for full assessment, In 25 of these cases there was no difference in the information provided by the hard-copy prints from fluoroscopic images and the postoperative check X-rays. In the other five cases, the differences were not significant. In none of the cases did the check X-ray effect a change in postoperative management. We therefore suggest that if per-operative hard-copy prints are obtained from the fluoroscopic images, postoperative radiographs of the ankle are only necessary in exceptional circumstances. (C) 1999 Elsevier Science Ltd. All rights reserved.

关键词：费用节省 X线透视检查/经济学 X线透视检查/标准骨折固定术内/经济学骨折/诊断显像骨折/经济学骨折/外科学辐射剂量放射摄影术/经济学放射摄影术/统计学和数值数据跗骨/诊断显像跗骨/损伤成年人老年人人类中年人

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An optical method of estimating the relative output of a superficial unit for small applicators

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PHYSICS IN MEDICINE AND BIOLOGY 2000年第7期45卷 N71-N76页

作者： Wilks, RJ Soni, KK Torbay Hosp Dept Med Phys Torquay England

The uncertainties associated with the measurement of the radiation output from a superficial x-ray unit are increased when using small applicators, as discussed in the text. The method described here uses two stages to measure the relative outputs: the first stage uses a large-diameter hat chamber to measure the radiation integrated over the applicator end, and the second stage uses an optical imaging system to investigate the shape of the beam. These are combined to produce a relative output for each applicator, which may then be transformed to an absolute output by applying the relative factors to a direct measurement of absolute output on one of the larger applicators.

关键词：生物物理学现象生物物理学剂量效应关系辐射图像处理计算机辅助放射摄影术/仪器和设备放射摄影术/统计学和数值数据散射辐射 X线

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