Impact of Increasing Margin Around the Lumpectomy Cavity to Define the Planning Target Volume for 3D Conformal External Beam Accelerated Partial Breast Irradiation

The purpose of this study was to evaluate the dose to normal tissues as a function of increasing margins around the lumpectomy cavity in accelerated partial breast irradiation (APBI) using 3D-conformal radiotherapy (3DCRT). Eight patients with Stage 0-I breast cancer underwent treatment planning for 3DCRT APBI. The clinical target volume (CTV) was defined as a 15-mm expansion around the cavity limited by the chest wall and skin. Three planning target volumes (PTV1, PTV2, PTV3) were generated for each patient using a 0, 5-, and 10-mm expansion around the CTV, for a total margin of 15, 20, and 25 mm. Three treatment plans were generated for every patient using the 3 PTVs, and dose-volume analysis was performed for each plan. For each 5-mm increase in margin, the mean PTV:total breast volume ratio increased 10% and the relative increase in the mean ipsilateral breast dose was 15%. The mean volume of ipsilateral breast tissue receiving 75%, 50%, and 25% of the prescribed dose increased 6% to 7% for every 5 mm increase in PTV margin. Compared to lesions located in the upper outer quadrant, plans for medially located tumors revealed higher mean ipsilateral breast doses and 20% to 22% more ipsilateral breast tissue encompassed by the 25% IDL. The use of 3DCRT for APBI delivers higher doses to normal breast tissue as the PTV increases around the lumpectomy cavity. Efforts should be made to minimize the overall PTV when this technique is used. Ongoing studies will be necessary to determine the clinical relevance of these findings.     

前牙唇侧齐龈肩台EMAX铸瓷全冠修复后唇侧牙周状况的评价

目的评价前牙唇侧齐龈肩台EMAX铸瓷全冠修复后唇侧牙周状况。方法对120颗前牙预备唇侧齐龈肩台,行EMAX铸瓷全冠修复。在修复前,修复后6个月,修复后1年和修复后2年分别采集唇侧龈沟液,测定龈沟液（gingivalcrevicular fluid,GCF）髓过氧化物酶（myeloperoxidase,MPO）的含量,同时记录唇侧牙周的牙龈指数（gingival index,GI）和牙周探诊深度（Pocket depths PD）。结果前牙EMAX铸瓷全冠在修复后6个月,修复后1年,修复后2年和修复前相比,牙龈指数GI、牙周探诊深度PD和龈沟液髓过氧化物酶MPO均无显著性差异（P〉0.05）。结论前牙EMAX铸瓷全冠修复体在临床上可获得理想的美学效果和边缘适应性,修复后2年唇侧牙周状况良好。     

Utility of teledermatopathology for intraoperative margin assessment of melanoma in situ,lentigo maligna type: A 6 year community practice experience

BackgroundAchieving negative margins for melanoma in situ, lentigo maligna type can be challenging, particularly on cosmetically sensitive areas.ObjectiveTo assess the utility of intraoperative frozen section margin assessment using a teledermatopathology system in the treatment of head and neck lentigo maligna.Methods and materialsOver a 6 year period, 96 patients with lentigo maligna had surgical excisions. The margins were assessed intraoperatively with frozen sections prepared in the manner used in Mohs surgery. The surgeon guided the frozen section slides around the margin while a dermatopathologist assessed the margin remotely.ResultsIn 2/96 (2.1%) cases, the safety margin was positive (frozen sections were false negative). In 1 further case (1%) there was a recurrence of the melanoma 13 months following the excision.ConclusionThe described method is effective in treating melanoma in situ, lentigo maligna type with clearance rates similar to previous studies for Mohs surgery.     

Machine learning methods applied to audit of surgical margins after curative surgery for head and neck cancer

Most surgical specialties have attempted to address concerns about the unfair comparison of outcomes by ‘risk-adjusting’ data to benchmark specialty-specific outcomes that are indicative of quality of care. We explore the ability to predict for positive margin status so that effective benchmarking that will account for complexity of case mix is possible. A dataset of care episodes recorded as a clinical audit of margin status after surgery for head and neck squamous cell carcinoma (n=1316) was analysed within the Waikato Environment for Knowledge Analyisis (WEKA) machine learning programme. The outcome was a classification model that can predict for positivity of tumour margins (defined as less than 1mm) using data on preoperative demographics, operations, functional status, and tumour stage. Positive resection margins of less than 1mm were common, and varied considerably between treatment units (19%-29%). Four algorithms were compared to attempt to risk-adjust for case complexity. The 'champion' model was a Naïve Bayes classifier (AUROC 0.72) that suggested acceptable discrimination. Calibration was good (Hosmer-Lemershow goodness-of-fit test p=0.9). Adjusted positive margin rates are presented on a funnel plot. Subspecialty groups within oral and maxillofacial surgery are seeking metrics that will allow for meaningful comparison of the quality of care delivered by surgical units in the UK. To enable metrics to be effective, we argue that they can be modelled so that meaningful benchmarking, which takes account of variation in complexity of patient need or care, is possible.     

Effect of software version and parameter settings on the marginal and internal adaptation of crowns fabricated with the CAD/CAM system

Objective

This study investigated the marginal and internal adaptation of individual dental crowns fabricated using a CAD/CAM system (Sirona’s BlueCam), also evaluating the effect of the software version used, and the specific parameter settings in the adaptation of crowns.

Material and Methods

Forty digital impressions of a master model previously prepared were acquired using an intraoral scanner and divided into four groups based on the software version and on the spacer settings used. The versions 3.8 and 4.2 of the software were used, and the spacer parameter was set at either 40 μm or 80 μm. The marginal and internal fit of the crowns were measured using the replica technique, which uses a low viscosity silicone material that simulates the thickness of the cement layer. The data were analyzed using a Friedman two-way analysis of variance (ANOVA) and paired t-tests with significance level set at p<0.05.

Results

The two-way ANOVA analysis showed the software version (p<0.05) and the spacer parameter (p<0.05) significantly affected the crown adaptation. The crowns designed with the version 4.2 of the software showed a better fit than those designed with the version 3.8, particularly in the axial wall and in the inner margin. The spacer parameter was more accurately represented in the version 4.2 of the software than in the version 3.8. In addition, the use of the version 4.2 of the software combined with the spacer parameter set at 80 μm showed the least variation. On the other hand, the outer margin was not affected by the variables.

Conclusion

Compared to the version 3.8 of the software, the version 4.2 can be recommended for the fabrication of well-fitting crown restorations, and for the appropriate regulation of the spacer parameter.     

Clinical relevance of frozen diagnosis of ductal margins in surgery of bile duct cancer

It is anticipated that free surgical margin is crucial for curative resection of bile duct cancer. However, the clinical relevance of the ductal margin is somewhat controversial. A role of frozen section diagnosis used for evaluation of the ductal margin during surgery is also ambiguous. We reviewed the current knowledge about frozen section diagnosis and the clinical relevance of the margin status in surgery of the bile duct cancer. Frozen section diagnosis of the ductal margin of bile duct cancer is necessary to ensure free margins; however, it is quite challenging even for experienced pathologists because the bile duct involved with bile duct cancer is often inflamed severely due to obstruction and/or insertion of a draining tube, which induces epithelial regeneration with atypia. Also accessory ducts/peribiliary glands and their conduits in ductal wall can mimic invasive ductal components, which requires careful examination to evaluate regenerative change, carcinoma in situ, or invasive carcinoma. Published studies assessing an association between the ductal margin state and prognosis in relatively large cohorts of patients undergoing surgery for bile duct cancer indicate that the ductal margin status is an independent prognostic factor; and the ductal margin with carcinoma in situ is comparable to free margin; however, the margin with invasive carcinoma is significantly adverse for patients' prognoses.     

Locust bean gum safety in neonates and young infants: An integrated review of the toxicological database and clinical evidence

Locust bean gum (LBG) is a galactomannan polysaccharide used as thickener in infant formulas with the therapeutic aim to treat uncomplicated gastroesophageal reflux (GER). Since its use in young infants below 12 weeks of age is not explicitly covered by the current scientific concept of the derivation of health based guidance values, the present integrated safety review aimed to compile all the relevant preclinical toxicological studies and to combine them with substantial evidence gathered from the clinical paediatric use as part of the weight of evidence supporting the safety in young infants below 12 weeks of age. LBG was demonstrated to have very low toxicity in preclinical studies mainly resulting from its indigestible nature leading to negligible systemic bioavailability and only possibly influencing tolerance. A standard therapeutic level of 0.5 g/100 mL in thickened infant formula is shown to confer a sufficiently protective Margin of Safety. LBG was not associated with any adverse toxic or nutritional effects in healthy term infants, while there are limited case-reports of possible adverse effects in preterms receiving the thickener inappropriately. Altogether, it can be concluded that LBG is safe for its intended therapeutic use in term-born infants to treat uncomplicated regurgitation from birth onwards.     

Digital breast tomosynthesis versus full-field digital mammography—Which modality provides more accurate prediction of margin status in specimen radiography?

ObjectivesTo evaluate the reliability of tumor margin assessment in specimen radiography (SR) using digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM) in comparison to postoperative histopathology margin status as the gold standard.MethodsAfter ethics committee approval, 102 consecutive patients who underwent breast conservative surgery for nonpalpable proven breast cancer were prospectively included. All patients underwent ultrasound/mammography-guided wire localization of their lesions. After excision, each specimen was marked for orientation and imaged using FFDM and DBT. Two blinded radiologists (R1, R2) independently analyzed images acquired with both modalities. Readers identified in which direction the lesion was closest to the specimen margin and to measure the margin width. Their findings were compared with the final histopathological analysis. True positive margin status was defined as a margin measuring <1 mm for invasive cancer and 5 mm for ductal carcinoma in situ (DCIS) at imaging and pathology.ResultsFor FFDM, correct margin direction was identified in 45 cases (44%) by R1 and in 37 cases (36%) by R2. For DBT, 69 cases (68%) were correctly identified by R1 and 70 cases (69%) by R2. Overall accuracy was 40% for FFDM and 69% for DBT; the difference was statistically significant (p < 0.0001). Sensitivity in terms of correct assessment of margin status was significantly better for DBT than FFDM (77% versus 62%).ConclusionSR using DBT is significantly superior to FFDM regarding identification of the closest margin and sensitivity in assessment of margin status.     

摆位随机误差对剂量分布的影响

目的 研究放疗中摆位随机误差对射线剂量分布的影响,确定治疗时CTV至PTV考虑随机误差需要设置的外放间距大小.方法 采用随机抽样方法模拟放疗时射线在靶区坐标系的位置,迭加后得到全部疗程的剂量分布,从而得到该疗程的90%剂量点位置的减小值.统计100个疗程的结果,按照95%的可能性确定从内靶体积(ITV)到PTV需要设置的外放间距大小,用Spearman秩相关分析各个因素对减小值的影响.结果90%剂量点位置的减小值只和随机误差大小有关,在随机误差1～6 mm时有效照射距离的改变值分别为0.62、1.84、3.13、4.78、6.34和8.03 mm,相关分析结果提示外放间距的大小只和随机误差的大小有关.结论 头颈部肿瘤和胸腹部肿瘤放疗时需要设置ITV到PTV的外放间距分别为1.2和1.5倍的随机误差,和随机误差相比,野大小、能量和深度和外放间距的大小关系不大.