Definition criteria for a magnetic resonance quality assurance program: multicenter study]

PURPOSE: We report the preliminary results of a multicenter trial aimed at defining methods, reference values and frequency of measurements for an MR quality assurance program. In particular, we stress the definition of two attention levels (investigation and intervention) for image uniformity and signal-to-noise ratio (SNR) by means of short- and long-term measurements. MATERIAL AND METHODS: The short-term protocol consisted of 10 successive spin-echo (SE, 2 echoes) acquisitions and was repeated after 24 hours. Measurements were made with the same test phantom which was circulated among all the participating centers. Image uniformity and SNR were evaluated using the software available on each MR unit. The long-term protocol, consisting of a single SE acquisition with the same parameters used for the short-term one, was performed once a month for 12 months. A mid term protocol was also performed twice a week for 5 weeks, and the analysis of the results is still in progress. RESULTS AND DISCUSSION: The short-term protocol results allowed absolute comparison of system performance. Uniformity and SNR were significantly different among centers (p < 0.05), also in the statistical comparison of two MR units of the same model (Siemens Magnetom SP63-1.5 T). Overall, three 1.5 T systems provided similar SNR values, while the results obtained for the 1 T system were markedly lower (51% of the maximum). This result can be explained by the dependence of the analytical expression of SNR on the magnetic field. The other 1.5 T system performed more poorly than the others operating at the same magnetic field. This difference can be explained by the specific characteristics of the coil and by technological aging. Because of the small sample size (5 units), the maximum variation coefficients (3% for the first echo and 3.5% for the second one) were assumed as a reference value for the both parameters (SNR and uniformity). These values were used for the long-term analysis: at every measurement the evaluated parameter was statistically compared with the result of the previous month. We propose to set an investigation level at p = 0.05: when the newly measured parameter differs from the previous value (p < 0.05), we should investigate if this is due to a normal long-term variation or to a system fault. The intervention level is then defined as the 95% prediction interval of the evaluated parameter regression vs time. Measurements that do not fall within the prediction interval are not used for future statistics. CONCLUSIONS: Some preliminary results concerning SNR and uniformity were obtained in the investigation performed on 5 MR systems to define methods and references for a Quality Assurance program. We introduced an "investigation level" and an "intervention level" related to short-term and long-term variability. The investigation levels could be a useful reference value to predict the short-term variability of an MR system with similar characteristics, thus avoiding a long and onerous series of measurements. Concerning the optimization of measurement frequencies, the preliminary analysis of these results showed that a daily measurement frequency is excessive in stable equipment conditions, while monthly measurements showed that the investigation level was often exceeded. However, frequency optimization will be investigated after the analysis of the mid-term measurements, which is still in progress.     

Antropyloric muscle thickness at US in infants: what is normal?

The authors reviewed the ultrasonographic (US) images and medical records of 145 consecutive infants who were seen for evaluation of the upper gastrointestinal tract because of chronic vomiting and/or regurgitation. At US, the antropyloric muscle of each patient was measured in the midlongitudinal plane. On the basis of this measurement, the patients were divided into the following categories: group 1 (1-2 mm; 99 patients), group 2 (greater than or equal to 3 mm; 40 patients), and group 3 (2- less than 3 mm; six patients). Patients in group 1 were considered to have normal antropyloric muscle thickness, those in group 2 had abnormal thickness, and those in group 3 had muscle thickness that was not definitely normal or abnormal. The final clinical diagnoses for all of the infants in the three groups confirmed the authors' initial impressions that antropyloric muscle thickness of less than 2 mm was anatomically normal, muscle measuring 3 mm or greater was abnormal and diagnostic for pyloric stenosis, and muscle from 2 to less than 3 mm was abnormal but not specifically diagnostic for pyloric stenosis. Two of the six patients in group 3 eventually were diagnosed as having pyloric stenosis; thus, the authors believe that only those patients with antropyloric muscle less than 2 mm thick should be considered unequivocably normal.     

Radiation safety and quality assurance in US dental hygiene programmes, 1990.

A 1990 survey of US dental hygiene programmes indicated substantial advances in radiation safety and quality assurance techniques since 1985. None the less, further improvements are possible to minimize operator and patient exposure to ionizing radiation from dental radiography. Conversion to faster receptor speed, the use of rectangular collimation and more frequent performance of quality assurance tests represent possible improvements for some establishments.     

Test object for measurement of section thickness at US

A simple phantom was used to test the ultrasound beam profile in the elevation direction (perpendicular to the scanning plane). Based on the inclined plane method, the phantom allowed direct clear display of the section thickness over the whole exploration depth on a single standard ultrasonographic image. This was demonstrated with one- and one and one-half-dimensional arrays. The results showed the efficiency of electronic focusing in the elevation plane associated with one and one-half-dimensional arrays.     

Reject analysis: its role in quality assurance

A reject analysis has been undertaken for a 26 week period in the radiology department of an oncological centre. The overall reject and repeat rates are presented here, as well as those arising from individual examinations and X-ray rooms. The variations in reject rates for different examinations as a function of time are highlighted and the role of reject analysis in quality assurance is discussed.     

Association of endometrial thickness assessed at trans-vaginal ultrasonography to endometrial cancer in postmenopausal women asymptomatic or with abnormal uterine bleeding

PURPOSE: To define the normal cut off of endometrial thickness as measured at transvaginal ultrasonography (TVUS) in order to define postmenopausal women without symptoms or with abnormal uterine bleeding (AUB) at risk of endometrial carcinoma (EC). MATERIALS AND METHODS: 3460 postmenopausal women (2240 asymptomatic, 1220 with AUB) undergoing TVUS. These series was linked with the Tuscany Cancer Registry archives in order to identify subjects who developed EC subsequent (within two years) to TVUS. RESULTS: Thickness (half layer) was significantly reduced in 2234 subjects not developing EC (1.68 mm; range = 0-20, SD 3.14) as compared to 6 subjects developing EC (4.67 mm, range = 0-10, SD 3.67) (p=0.02). A 4 mm cut off was associated with a sensitivity of 66.7%, a specificity of 92.1%, a positive predictive value of 2.2% and a negative predictive value of 99.9%. Similarly, in subjects with AUB, thickness (half layer) was significantly smaller in the 1175 subjects not developing EC (2.46 mm, range 0-20, SD 3.59) as compared to 45 subjects developing EC (8.0 mm, range 0-44, SD 6.76) (p<0.001). The best cut off for clinical purposes was 4 mm, with a sensitivity of 91.1%, a specificity of 79.8%, a positive predictive value of 14.8% and a negative predictive value of 99.6%. CONCLUSIONS: The study confirms the usefulness of measuring endometrial thickness (half layer cut off = 4 mm) with TVUS in asymptomatic postmenopausal women, both in asymptomatic subjects to indicate further special surveillance and in subjects with AUB to indicate immediate invasive assessment.     

三维超声经阴道对子宫内膜息肉的诊断价值

目的:探讨三维超声经阴道对子宫内膜息肉的诊断价值。方法:应用Voluson 730超声诊断仪对32例子宫内膜息肉患者进行三维超声经阴道检查,并进行三维重组。结果:三维超声经阴道诊断子宫内膜息肉中32例有30例与病理结果显示相符合,符合率为94%。结论:三维超声经阴道检查能直接显示子宫及宫腔内病灶的立体形态及与内膜的空间关系,使诊断准确率进一步提高。     

Gas within the endometrial cavity at postpartum US: a normal finding after spontaneous vaginal delivery.

In the puerperium, the detection of gas within the endometrial cavity at ultrasound (US) has been commonly taken to indicate endometritis. Of 70 clinically healthy women in whom US was performed after uncomplicated spontaneous vaginal delivery, 13 (19%) had evidence of gas in the endometrial cavity within the first 3 postpartum days (mean, 37 hours; range, 25-59 hours) and five (7%) had such evidence in the 3rd week after delivery (mean, 2.4 weeks; range, 2.1-2.9 weeks). Gas was seen in the endometrial cavity on at least one occasion during the first 3 postpartum weeks in 15 (21%) of these apparently healthy women; in no case did clinical evidence of endometritis develop. From these observations, the authors believe that gas detected within the endometrial cavity is not, in and of itself, suggestive of endometritis, and that such a finding should be considered normal, at least until the end of the 3rd postpartum week.     

Colonic diseases: the value of US examination

The colon is affected by a number of diseases, mainly inflammatory, ischemic, and neoplastic conditions. Depending upon clinical indications endoscopy, US, CT, or other radiological methods are used for evaluation. The fact that US is frequently used as the initial imaging method in patients with non-specific clinical symptoms allows for greater influence in further diagnostic evaluation and with treatment, provided the investigator is familiar with the features of different intestinal diseases. This article will describe the anatomical characteristics of the colon, the US technique for examination of the colon, and the typical US features of the more common diagnoses of the colon.     

Paediatric medulloblastoma: patterns of care and radiotherapy quality assurance in Australia

The purpose of this study was to document how children in Australia with medulloblastoma are being treated and to evaluate the quality of radiotherapy (RT) delivered. The Radiotherapy Database of the Australian and New Zealand Children's Haematology and Oncology Group was used to identify 46 children with medulloblastoma younger than the age of 15 years treated with radical intent by craniospinal irradiation between 1997 and 1999 inclusively. Twenty-six patients had completely resected disease without evidence of disease spread. Of these, 16 patients received a craniospinal RT dose of <25 Gy in addition to chemotherapy. RT treatment immobilization methods varied, as did planning methods. RT dose to critical structures was recorded on treatment plans for only 15% of patients. The average systematic error in shield placement at the posterior orbit was 5.2 mm, and two-thirds of patients were 'overshielded' at this site. Adequate coverage of the distal end of the thecal sac was achieved in fewer than 50% of on-treatment verification films for 21 of 45 patients. With a reduction in RT dose to the craniospinal axis for paediatric medulloblastoma, greater attention is needed for patient immobilization, documentation of RT dose to critical structures and the placement and reproducibility of shielding.     

Medical and physical aspects of quality assurance in radio-oncology

A more extensive interpretation of quality control in radio-oncology is opposed to the conception mostly restricted to technical inspections. A review is given of the most important medical and physical aspects of an optimized radiotherapy. Some examples are chosen from the great number of national and international recommendations agreed upon in order to standardize the measures of quality control. Finally some simple radiobiologic models are presented and the corresponding precision requirements are compared with the uncertainties of the dose determination resulting in clinical practice.     

Impact of the introduction of weekly radiotherapy quality assurance meetings at one UK cancer centre

Objective:

The complexity of radiotherapy planning is increasing rapidly. Delivery and planning is subject to detailed quality assurance (QA) checks. The weakest link is often the oncologists'' delineation of the clinical target volume (CTV). Weekly departmental meetings for radiotherapy QA (RTQA) were introduced into the Royal Wolverhampton Hospital, Wolverhampton, UK, in October 2011. This article describes the impact of this on patient care.

Methods:

CTVs for megavoltage photon radiotherapy courses for all radical, adjuvant and palliative treatments longer than five fractions (with the exception of two field tangential breast treatments not enrolled into clinical trials) were reviewed in the RTQA meeting. Audits were carried out in January 2012 (baseline) and September 2013, each over a 4-week period. Adherence to departmental contouring protocols was assessed and the number of major and minor alterations following peer review were determined.

Results:

There was no statistically significant difference for major alterations between the two study groups; 8 alterations in 80 patients (10%) for the baseline audit vs 3 alterations from 72 patients (4.2%) in the second audit (p = 0.17). A trend towards a reduction in alterations following peer review was observed. There has, however, been a change in practice resulting in a reduction in variation in CTV definition within our centre and greater adherence to protocols. There is increasing confidence in the quality and constancy of care delivered.

Conclusion:

Introduction of a weekly QA meeting for target volume definition has facilitated consensus and adoption of departmental clinical guidelines within the unit.

Advances in knowledge:

The weakest areas in radiotherapy are patient selection and definition of the CTV. Engagement in high-quality RTQA is paramount. This article describes the impact of this in one UK cancer centre.The complexity of radiotherapy planning has increased rapidly over the past decade in the UK with the introduction of three-dimensional conformal therapies and more recently intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy.^1,2 Delivery and planning of radiotherapy is subject to detailed quality assurance (QA) checks. The two widest variables in this process are delineation of the clinical target volume (CTV) by the oncologist and patient selection.^3–6 There is an expanding body of literature from clinical trials confirming that deviation from radiation outlining protocols is associated with an increase in the risk of treatment failure and mortality.^7–9 In the Trans-Tasman Radiation Oncology Group 02.02 study for advanced head and neck cancer, 12% of treatments were considered at QA review to have a protocol violation, which represented a major deficiency, predicting reduced local control. Considering only those patients who received >60 Gy, the overall survival and locoregional control for patients with major deficiencies in the treatment plan were 50% and 54%, respectively, compared with 70% and 78% for those whose treatment plan was protocol compliant (p < 0.001).⁸ Efforts to improve quality and consistency of radiotherapy within co-operative groups is essential for interpretation of data; however, translating results of studies into clinical practice requires adoption of the same approach within local multidisciplinary teams (MDTs).Radiotherapy QA (RTQA) clinical meetings to review CTV delineation are common place in Europe, the USA and Australasia but are not routine in the UK.^10–13 At the Royal Wolverhampton Hospital, Wolverhampton, UK, a weekly RTQA was commenced in October 2011. The RTQA is a considerable investment in resources by the trust. Outcomes of the meeting were audited to assess impact on the quality of patient care.     

多囊卵巢综合征的子宫内膜厚度及卵巢血液改变的超声诊断

目的探讨多囊卵巢综合征(PCOS)的子宫内膜厚度及卵巢血液改变的超声诊断价值。方法对47例多囊卵巢综合征患者(PCOS组)和32例健康人(对照组)进行超声检查,观察子宫内膜的厚度及卵巢血液参数变化。结果PCOS组的子宫内膜厚度和收缩期峰值血流速度(PSV)明显大于对照组,差异有统计学意义(P<0.05),不同停经天数PCOS患者的子宫内膜厚度和卵巢PSV差异有统计学意义,以>90 d组的值最高;PCOS组和对照组卵巢的阻力指数(RI)差异有统计学意义,PCOS组明显低于对照组(P<0.05),不同停经天数PCOS患者的卵巢RI值差异有统计学意义,以>90 d组的值最低。结论超声检查显示PCOS患者的子宫内膜增厚,卵巢血流丰富,阻力明显减低,并且随停经时间而变化。超声诊断对于PCOS具有重要的临床意义。