Comparison of modeling accuracy between Radixact®and CyberKnife®Synchrony®respiratory tracking system.

Synchrony Respiratory Tracking system adapted from CyberKnife has been introduced in Radixact to compensate the tumor motion caused by respiration. This study aims to compare the modeling accuracy of the Synchrony system between Radixact and CyberKnife. Two Synchrony plans based on fiducial phantoms were created for CyberKnife and Radixact, respectively. Different respiratory motion traces were used to drive a motion platform to move along the superoinferior and left-right direction. The cycle time and the amplitude of target/surrogate motion of one selected motion trace were scaled to investigate the dependence of modeling accuracy on the motion characteristic. The predicted target position, the correlation error, potential difference (Radixact only) and standard error (CyberKnife only) were extracted from raw data or log files of the two systems. The modeling accuracy was evaluated by calculating the root-mean-square (RMS) error between the predicted target positions and the input motion trace. A threshold T95 within which 95% of the potential difference or the standard error lay was defined and evaluated. Except for the motion trace with a small amplitude and a good (linear) correlation between target and surrogate motion, Radixact showed smaller RMS errors than CyberKnife. The RMS error of both systems increased with the motion amplitude and showed a decreasing trend with the increasing cycle time. No correlation was found between the RMS error and the amplitude of surrogate motion. T95 could be a good estimator of modeling accuracy for CyberKnife rather than Radixact. The correlation error defined in Radixact were largely affected by the number of fiducial markers and the setup error. In general, the modeling accuracy of the Radixact Synchrony system is better than that of the CyberKnife Synchrony system under unfavorable conditions.

Initial clinical experience of patient-specific QA of treatment delivery in online adaptive radiotherapy using a 1.5 T MR-Linac.

Purpose. This study aims to evaluate the performance of a commercial 1.5 T MR-Linac by analyzing its patient-specific quality assurance (QA) data collected during one full year of clinical operation.Methods and Materials. The patient-specific QA system consisted of offline delivery QA (DQA) and online calculation-based QA. Offline DQA was based on ArcCHECK-MR combined with an ionization chamber. Online QA was performed using RadCalc that calculated and compared the point dose calculation with the treatment planning system (TPS). A total of 24 patients with 189 treatment fractions were enrolled in this study. Gamma analysis was performed and the threshold that encompassed 95% of QA results (T95) was reported. The plan complexity metric was calculated for each plan and compared with the dose measurements to determine whether any correlation existed.Results. All point dose measurements were within 5% deviation. The mean gamma passing rates of the group data were found to be 96.8 ± 4.0% and 99.6 ± 0.7% with criteria of 2%/2mm and 3%/3mm, respectively. T95 of 87.4% and 98.2% was reported for the overall group with the two passing criteria, respectively. No statistically significant difference was found between adaptive treatments with adapt-to-position (ATP) and adapt-to-shape (ATS), whilst the category of pelvis data showed a better passing rate than other sites. Online QA gave a mean deviation of 0.2 ± 2.2%. The plan complexity metric was positively correlated with the mean dose difference whilst the complexity of the ATS cohort had larger variations than the ATP cohort.Conclusions. A patient-specific QA system based on ArcCHECK-MR, solid phantom and ionization chamber has been well established and implemented for validation of treatment delivery of a 1.5 T MR-Linac. Our QA data obtained over one year confirms that good agreement between TPS calculation and treatment delivery was achieved.

Low-cost Kinect Version 2 imaging system for breath hold monitoring and gating: Proof of concept study for breast cancer VMAT radiotherapy.

Voluntary inspiration breath hold (VIBH) for left breast cancer patients has been shown to be a safe and effective method of reducing radiation dose to the heart. Currently, VIBH protocol compliance is monitored visually. In this work, we establish whether it is possible to gate the delivery of radiation from an Elekta linac using the Microsoft Kinect version 2 (Kinect v2) depth sensor to measure a patient breathing signal. This would allow contactless monitoring during VMAT treatment, as an alternative to equipment-assisted methods such as active breathing control (ABC). Breathing traces were acquired from six left breast radiotherapy patients during VIBH. We developed a gating interface to an Elekta linac, using the depth signal from a Kinect v2 to control radiation delivery to a programmable motion platform following patient breathing patterns. Radiation dose to a moving phantom with gating was verified using point dose measurements and a Delta4 verification phantom. 60 breathing traces were obtained with an acquisition success rate of 100%. Point dose measurements for gated deliveries to a moving phantom agreed to within 0.5% of ungated delivery to a static phantom using both a conventional and VMAT treatment plan. Dose measurements with the verification phantom showed that there was a median dose difference of better than 0.5% and a mean (3% 3 mm) gamma index of 92.6% for gated deliveries when using static phantom data as a reference. It is possible to use a Kinect v2 device to monitor voluntary breath hold protocol compliance in a cohort of left breast radiotherapy patients. Furthermore, it is possible to use the signal from a Kinect v2 to gate an Elekta linac to deliver radiation only during the peak inhale VIBH phase.

The effect of economic insecurity on mental health: Recent evidence from Australian panel data.

This paper estimates the impact of economic insecurity on the mental health of Australian adults. Taking microdata from the 2001-2011 HILDA panel survey, we develop a conceptually diverse set of insecurity measures and explore their relationships with the SF-36 mental health index. By using fixed effects models that control for unobservable heterogeneity we produce estimates that correct for endogeneity more thoroughly than previous works. Our results show that exposure to economic risks has small but consistently detrimental mental health effects. The main contribution of the paper however comes from the breadth of risks that are found to be harmful. Job insecurity, financial dissatisfaction, reductions and volatility in income, an inability to meet standard expenditures and a lack of access to emergency funds all adversely affect health. This suggests that the common element of economic insecurity (rather than idiosyncratic phenomena associated with any specific risk) is likely to be hazardous. Our preferred estimates indicate that a standard deviation shock to economic insecurity lowers an individual's mental health score by about 1.4 percentage points. If applied uniformly across the Australian population such a shock would increase the morbidity rate of mental disorders by about 1.7%.

Placa abollonada en surco nasogeniano / Nodular Plaque in the Nasolabial Fold

No disponible

Individualized treatment of NSCLC: from research to clinical practice.

The exact clinical significance of EGFR mutation status in NSCLC at the time of initial diagnosis remains disputable. The gene expression module in NSCLC for chemotherapy outcome prediction needs to be developed. We analyzed 56 patients with NSCLC received chemotherapy either with (n=20) or without EGFR-TKIs (n=36) between 2008 and 2012 in China. EGFR mutation test and gene expression profiling were performed in samples obtained before medication treatment by liquidchip platform. Significant association (P = 0.028) was seen between EGFR mutation status before first-line chemotherapy and EGFR-TKIs treatment outcomes, which even can be found from the status before second- or third-line treatment. A14-gene expression profiling had been studied. Patients with low mRNA expression of ERCC1 or TYMS preferred higher DCR to cisplatin and pemetrexed than those with high expression (P = 0.39 and P= 0.11). Highly co-expression of TUBB3 and STMN1 gene has associated with the resistance to antimicrotubule drugs (P = 0.03). Our data suggest the EGFR mutations status, even at the time of initial diagnosis, is predictive of outcomes of TKIs treatment after chemotherapy. The mRNA expression profiling investigated in this study has a predictive value in NSCLC treatment, but further research with expanded samples is still required.

Monophasic, solitary tumefactive demyelinating lesion: neuroimaging features and neuropathological diagnosis.

The characteristic clinicoradiological findings of multiple sclerosis and acute disseminated encephalomyelitis (ADEM), demonstrating a recurrent progressive course in the former and monophasicity in the latter associated with multiple discrete white matter lesions with variable enhancement on MRI, are not a diagnostic challenge. On the other hand, the less typical radiological presentation of a solitary tumefactive demyelinating lesion mimics a neoplasm, and often necessitates a biopsy. Nonetheless, histopathological examination is an imperfect gold standard and the recognition of certain imaging features may facilitate the correct diagnosis.

Pericardial effusion after open heart surgery for congenital heart disease.

OBJECTIVES: To determine the prevalence and time course of pericardial effusion after open heart surgery for congenital heart diseases and to identify predisposing risk factors. DESIGN AND PATIENTS: Prospective assessment of development of pericardial effusion in 336 patients (163 males) undergoing open heart surgery for congenital heart disease by serial echocardiography on days 5, 7, 14, 21, and 28 postoperatively. SETTING: Tertiary paediatric cardiac centre. RESULTS: The prevalence of pericardial effusion was 23% (77 of 336). Of the 77 patients who developed effusion, 43 (56%) had moderate to large effusions and 18 (23%) were symptomatic. Patients who had a large amount of effusion were more likely to be symptomatic than those with only a small to moderate amount (47.4% v 15.5%, p = 0.01). The mean (SD) onset of pericardial effusion was 11 (7) days after surgery, with 97% (75 of 77) of cases being diagnosed on or before day 28 after surgery. The prevalence of effusion after Fontan-type procedures (60%, 6 of 10) was significantly higher than that after other types of cardiac surgery: repair of left to right shunts (22.1%, 43 of 195), repair of lesions with right ventricular outflow tract obstruction (22.6%, 19 of 84), arterial switch operation (6.7%, 1 of 15), and miscellaneous procedures (25%, 8 of 32) (p = 0.037). Univariate analyses showed that female patients (p = 0.009) and those receiving warfarin (p = 0.002) had increased risk of postoperative pericardial effusion. A greater pericardial drain output in the first four hours after surgery also tended to be significant (p = 0.056). Multivariate logistic regression similarly identified warfarin treatment (beta = 1.73, p = 0.009) and female sex (beta for male = -0.63, p = 0.037) as significant determinants. CONCLUSIONS: Pericardial effusion occurs commonly after open heart surgery for congenital heart disease. Serial echocardiographic monitoring up to 28 days postoperatively is indicated in selected high risk patients such as those with symptoms of postpericardiotomy syndrome and those given warfarin.

Is postoperative deep vein thrombosis a problem in neurosurgical patients with brain tumours in Singapore?

AIM: To prospectively establish the incidence of deep vein thrombosis (DVT) after cranial procedures in patients with brain tumour in Singapore. METHODOLOGY: Over a period of one year from June 1995 to May 1996, 106 consecutive patients were recruited into the study. All patients undergoing surgery within the period of study were included. Each patient underwent a preoperative and postoperative (on postoperative Day 5 to Day 7) ultrasound examination of the lower limbs to establish the presence of DVT. Prophylaxis was limited to the peri-operative use of elastic stockings on hemiparetic limbs. There were 56 males and 50 females aged between 22 to 86 years (median 45 years). Ethnicity was Chinese, 92% Indian, 6% and other 2%. Ninety percent of the patients were ambulant pre- and post-operatively. No patient had a prior history of DVT. The distribution by pathologic diagnosis was brain metastases, 26% meningioma, 26% glioma, 19% pituitary adenoma, 14% acoustic neuroma, 6% and 9% miscellaneous tumours. RESULTS: DVT was identified in 5/106 patients (4.7%), all of whom had either meningioma or glioma. All five cases occurred in supratentorial tumours. The tumour specific incidence was 7.1% for meningioma and 15% for glioma. 4/5 patients (80%) had pre-existing hemiparesis of the affected limb. No patient developed clinical pulmonary embolism. CONCLUSION: The overall incidence of postoperative DVT in our population, using minimal prophylaxis, was not significantly different from the best results of prospective studies on North American or European patients employing a full regime of prophylaxis. The high-risk groups were similar. Prophylaxis using subcutaneous heparin should be used cautiously in high-risk patients.

Review of carotid endarterectomy at Singapore General Hospital.

AIM: To review the outcome of a consecutive series of patients undergoing carotid endarterectomy in a low volume setting. DESIGN: Retrospective case review. PATIENTS: During an 11-year period we performed 50 elective carotid endarterectomies on patients with symptomatic severe carotid stenosis: Ages of patients raised from 40 to 87 years (mean 68 years), 88% were Chinese, 6% Malay and 4% Indian. Twenty-eight percent had coronary artery disease, 64% hypertension, 27% diabetes mellitus, 50% hyperlipidaemia, and 52% were smokers. None of the patients had prior neck surgery or radiotherapy. RESULTS: There were no deaths in this series of 50 cases. Ninety-eight percent of our patients came through surgery without major neurologic deficit. One patient (2%) suffered a major perioperative stroke. Minor neurologic sequelae included one patient (2%) with a mild non-disabling stroke, two patients (4%) with peri-operative TIA without significant sequelae; two patients (4%) with transient cranial nerve weakness (one vagus, one facial nerve). CONCLUSION: The surgical outcomes in this series are comparable to that from larger series. Carotid endarterectomy can be safely done in a low volume setting.

Radon properties in offices.

The radon concentration (RC), total potential alpha energy concentration of radon decay products (PAEC), equilibrium factor (F), and the fraction of unattached radon decay products (fp) were measured for 94 offices in Hong Kong. The mean values for RC, PAEC, F, and fp were 51 Bq m(-3), 1.19x10(-7) J m(-3) (5.7 mWL), 0.43, and 0.13, respectively. The first three are much higher than the corresponding values for dwellings. The radon properties vary significantly for different sites. The time for measurements, cumulative time since the air conditioning system was turned on, and whether smoking is allowed in the office have been identified from the available data as possible factors affecting the radon characteristics in offices. The mean contribution of the lung exposure to the annual effective dose equivalent due to radon in offices has been calculated to be 0.35 mSv y(-1). Considering other sources of natural radiation, a rough estimate of the total annual equivalent dose of about 2.7 mSv for a person living in Hong Kong is obtained. Two simple methods are proposed to mitigate the radon hazard in offices: (1) the provision of smoke-free environments and (2) switching on the air conditioners earlier. The first method reduces the equivalent dose by about 0.13 mSv y(-1) while the second reduces by about 0.1 mSv y(-1), which can be regarded as significant.

Video-endoscopic and mini-endoscopic sympathectomy for hyperhidrosis.

Video-endoscopic sympathectomy (VES) is currently the method of choice for the minimally invasive treatment of hyperhidrosis involving the palms, armpit and facial areas. Over a 7-year period from 1991 to 1997 our technique of performing VES has evolved during the performance of 800 endoscopic sympathectomies from the use of 3 ports to a single 10-mm port to finally a 3-mm port using a mini-endoscope. In comparison to standard VES, mini-endoscopic sympathectomy is simpler, less invasive, causes less postoperative discomfort and consistently allows patients to return home the same day.

Cognitive-behavioural group therapy for Hong Kong Chinese adults with mental health problems.

Ninety-one Chinese in the community, aged between 18 and 45, with mental health problems ranging from mild to moderate degree, were treated by cognitive behavioural group therapy (CBGT) for a period of 3 months. All subjects were assessed on multiple measures at 4 time points: screening, pre-treatment (after 3 months), post-treatment and at 3-month follow-up. Attendance was good. A standard practice manual was developed to ensure consistent treatment by 2 group workers. After controlling for the placebo effect in the waiting period, treatment effect was demonstrated which was sustained after a three month period. The all-round improvement included a decrease in psychiatric symptoms, improvement in self-assessment, better and more social activities and being more able to cope with problems. In terms of psychiatric diagnosis, depressed subjects gained the most benefit and personality disorder subjects the least. Parents seemed to benefit more than non-parents.