Developing a novel quasi-3D movable water phantom for radiation therapy workable in the magnetic resonance environment

Background

The use of magnetic resonance linear accelerators (MR-LINACs) for clinical treatment has opened up new possibilities and challenges in the field of radiation oncology. However, annual quality assurance (QA) is relatively understudied due to practical considerations. Thus, to overcome the difficulty of measuring the dose with a small water phantom for TRS-398 or TG-51 in all external beam radiation treatment unit environments, such as MR compatibility, we designed a remote phantom with a three-axis changeable capacity for QA.

Methods

The designed water phantom was tested under an MR environment. The water phantom system comprised of three parts: a phantom box, a dose measurement tool, and a PMD401 drive system. The UNIDOSE universal dosimeter was used to collect beam data. The manufacturer's developer tools were utilized to position the measurement. To ensure magnetic field homogeneity, a distortion phantom was prepared using sixty fish oil capsules aligned radially to distinguish the oil and free air. The phantom was scanned in both the MR simulator and computed tomography (CT), and the acquired images were analyzed to determine the position shift.

Results

The dimensions of the device are 30 cm in the X-axis, 20 cm in the Y-axis, and 17 cm in the Z-axis. Total cost of materials was no more than $10,000 US dollars. Our results indicate that the device can function normally in a regular 1.5 T MR environment without interference from the magnetic field. The water phantom's traveling speed was found to be approximately 5 mm/s with a position difference confined within 6 cm intervals during normal use. The distortion test results showed that the prepared MR environment has uniform magnetic field homogeneity.

Conclusions

In this study, we constructed a prototype water phantom device that can function in an MR simulator without interference between the magnetic field and electronic components. Compared to other commercially available MR-LINAC water phantoms, our device offers a more cost-effective solution for routine monthly QA. It can shorten the duration of QA tests and relieve the burden on medical physicists.

Salispheres from Different Major Salivary Glands for Glandular Regeneration

Dysfunctional salivary glands (SGs) are a clinical challenge due to the lack of effective treatments. Cell therapy with stem/progenitor cells may improve this situation by providing promising therapeutic solutions. Therefore, exploring abundant cellular sources is important. Three major pairs of SGs are located in different anatomic regions: the parotid glands, the submandibular glands, and the sublingual glands. Although SG stem/progenitor cells can be isolated and cultivated from all major SGs as salispheres, the differences among SG origins remain unclear. In this study, salispheres were successfully isolated from all major SGs. The salispheres demonstrated unique cellular features that originated from their native tissues. The characteristic expression profiles and cellular features of SG stem cells were demonstrated in all salispheres. When they were transplanted into irradiated animals, the salispheres were all capable of improving the saliva secretion that was disrupted by irradiation. Typical histologic structures could be observed in most parts of the treated glands, and the fibrotic environments of irradiated submandibular glands were remodeled by all salispheres regardless of origins. This study characterized the cellular features and in vivo effects of salispheres that were derived from different anatomic origins. The results suggest the possibility of functional redundancy among distinct pairs of major SGs, which is useful for the design of cell therapy to treat dysfunctional glandular organs.

A Solution to Modeling Multilevel Confirmatory Factor Analysis with Data Obtained from Complex Survey Sampling to Avoid Conflated Parameter Estimates

The issue of equality in the between-and within-level structures in Multilevel Confirmatory Factor Analysis (MCFA) models has been influential for obtaining unbiased parameter estimates and statistical inferences. A commonly seen condition is the inequality of factor loadings under equal level-varying structures. With mathematical investigation and Monte Carlo simulation, this study compared the robustness of five statistical models including two model-based (a true and a mis-specified models), one design-based, and two maximum models (two models where the full rank of variance-covariance matrix is estimated in between level and within level, respectively) in analyzing complex survey measurement data with level-varying factor loadings. The empirical data of 120 3rd graders' (from 40 classrooms) perceived Harter competence scale were modeled using MCFA and the parameter estimates were used as true parameters to perform the Monte Carlo simulation study. Results showed maximum models was robust to unequal factor loadings while the design-based and the miss-specified model-based approaches produced conflated results and spurious statistical inferences. We recommend the use of maximum models if researchers have limited information about the pattern of factor loadings and measurement structures. Measurement models are key components of Structural Equation Modeling (SEM); therefore, the findings can be generalized to multilevel SEM and CFA models. Mplus codes are provided for maximum models and other analytical models.

Primary antiphospholipid syndrome manifested as venous stasis retinopathy

Primary antiphospholipid syndrome is a condition in which antiphospholipid antibodies may be present without any associated medical disorder. Thrombosis is the hallmark of this syndrome. We report the case of a 22-year-old female with the chief complaint of floating spots in the right eye for two months. No underlying connective tissue disease or systemic disease was noted. Ophthalmic examination revealed retinal hemorrhage, retinal vein engorgement and optic disk swelling in the right eye only, and normal visual acuity in both eyes. Retinal fluorescein angiography showed venous stasis and branch vein leakage in the right eye. An antibody profile revealed the presence of immunoglobulin G anticardiolipin antibodies, which confirmed the diagnosis of primary antiphospholipid syndrome.

[Respiratory failure after nebulized terbutaline treatment in severely wheezy infants: report of three cases]

Subjective clinical observations have suggested that nebulized bronchodilators are helpful in the treatment of some wheezy infants. Although the role of beta 2-agonists in the management of acute asthma in infants and very young children remains controversial, the use of beta 2-adrenergic agents in this age group has been widespread. beta 2-agonists nebulization continues to be the first-line treatment for acute attack of asthma, irrespective of age, in some institutes, but their uses are not without side effect especially in young wheezy infants. We report three cases of respiratory failure occurred after treatment with nebulized beta 2 bronchodilator in infants with chronic lung disease and acute wheezing. All the 3 cases were victims of prematurity. Case 1 was a case of Wilson-Mikity syndrome; case 2 was a case of bronchopulmonary dysplasia; and case 3 was a case of repeatedly wheezing infant. All 3 cases had severely wheezy dyspnea with retraction before nebulized beta 2 bronchodilator treatment. Respiratory failure was found 5 to 10 minutes after the treatment. We suggest that it must be very careful in the treatment of severely wheezy infants with beta 2-agonist nebulization, especially in cases with histories of prematurity and chronic lung disease. It is necessary to carefully monitor the vital signs of the infants during beta 2 agonist nebulization.

[Fetus in fetu: report of a single case]

A five-year-old girl had been noted, since birth to have abdominal distension. There was no history of twinning or teratoma in the family. Physical examination discovered a 15 x 10 cm mass in the abdomen. Roentgenologic examination demonstrated the presence of an axial skeleton and long bones within the mass. MRI showed a retroperitoneal mass with components of cystic, bony and fatty tissues. When the mass was surgically removed from the retroperitoneal cavity, pathologic examination disclosed a parasitic fetus measuring 15.3 x 6.3 x 6.0 cm in size and suspended by a peduncle within a capsule. The fetus was covered with skin, sebaceous materials and black hair. There were bilateral and symmetric upper extremities with a flapper-like, deformed hand. No obvious genital organ was noted. Dissection of the midline, revealed a vertebral column with spinal cord. An atrophic skull bone containing cephalized glial tissue was noted. A thoracic cavity and scapular bone were found in the thoracic cage; however, no heart was noted. Gastrointestinal tract and kidney-like organs were seen within the abdominal cavity. Microscopically, there were glial tissues within the skull bone, spinal cord and vertebra. The upper extremities revealed two long bones surrounded by myxomatous and fibrous tissue. A well developed intestine and an ovary containing follicles with nearby lympy nodes were seen. The capsule showed fibrous tissue with calcification and hairs. It was distinguished from the teratoma by the presence of a vertebral axis and by an appropriate arrangement of other organs or limbs with respect to the axis, and corresponding to the generally recognized diagnostic criteria of fetus in fetu.

Ultrastructural alterations in cardiac muscle of diabetic BB Wistar rats

The cardiac muscle of BB Wistar rats suffering from diabetes for 8 and 16 weeks (8-Wk and 16-Wk of DM) were examined by light and electron microscopy. The diabetic rats were kept alive by injections of small doses of insulin and exhibited severe hyperglycaemia, glycosuria and weight loss. The heart/body weight ratio of all diabetic groups was greater than that of age matched controls. Over the experimental period, the left ventricular myocardium of the diabetic BB rats sustained damage that was progressively more serious with the duration of the diabetic state. In BB rats after 8-wk of diabetes the myocardium contained large numbers of lipid droplets and glycogen granules around mitochondria which showed patchy swelling, and slight loss of myofilaments. Disruption of mitochondrial membranes and extensive loss of myofilaments were seen in rats diabetic for 16 wk. In addition, dilatation of the sarcoplasmic reticulum-transverse tubular system, formation of a contraction band and myelin bodies and widening of the intercellular space at the fasciae adherens of the intercalated disc were characteristically observed in BB rats after 16-wk of diabetes. However, there were no evident alterations in the capillaries of any diabetic BB rats. Morphometric analyses showed the volume percentage of myofibrils in diabetic rats to be significantly decreased when compared with controls. The loss of myofibrillar elements may be a primary damage induced by insulin deficiency. The formation of contraction bands suggests Ca2+ overload caused by diabetic metabolic disturbances.