Soft Tissue Features Research Articles

High-Frequency Ultrasound Assessment of Skin and Oral Mucosa in Metabolic Syndrome Patients—A Cross-Sectional Study

Background: Exogenous factors (such as sun exposure, smoking habits, and diet) and endogenous (inflammatory status, general diseases) have a direct influence on skin and soft tissue characteristics. The study’s objective was to assess the impact of metabolic syndrome (MS) on characteristics of skin layers in sun-exposed and non-exposed maxillofacial tissues evaluated by high-frequency ultrasound (HFU), as a potential diagnosis and monitoring tool for the aging process. Material and methods: The present study included 102 subjects (24 with MS; 78 without MS). Anthropometric parameters and disease history were recorded, and blood samples were harvested in order to assess biochemical parameters of MS. Sun-exposed skin (zygomatic region) and non-exposed oral mucosa of the lower lip were assessed using HFU (DUB® cutis, Taberna Pro Medicum) with a 22 MHz probe. Results: Patients with cardiac disease had significantly lower values for epidermis density (p = 0.002). Gender was independently linked to the aged dermis depth (p < 0.001), aged dermis no. of px (pixels) (p < 0.001), dermis depth (p < 0.001), dermis no. of px (p < 0.001), and subcutaneous tissue density (p < 0.001). Patients with MS had thinner epidermis (p = 0.008) and thinner aged dermis (p = 0.037) when compared to non-MS subjects. Conclusion: Patients with MS had thinner epidermis and a lower epidermis number of pixels in sun-exposed skin. Women had lower epidermis density and thicker dermis in sun-exposed skin. Our study showed that HFU, as a non-invasive investigation approach, is useful to diagnose and monitor the aging process in skin and oral mucosa, correlated with skin phenotype pathological conditions.

P–679 Magnetic resonance imaging (MRI), an alternative method to evaluate the ovarian reserve

Abstract Study question Is magnetic resonance imaging (MRI) a valid method to access antral follicles count (AFC) compared to two-dimensional (2D) transvaginal ultrasonography (USG) and Anti-Mullerian Hormone (AMH) to evaluate the ovarian reserve? Summary answer AFC has a high agreement between MRI and USG methods, as well as with AMH. MRI can be an alternative method to evaluate ovarian reserve. What is known already In fact, two methods are the most used today to assess ovarian reserve: USG and AMH. The USG is considered the gold standard method for AFC, and contributes to predict and tailor treatment strategies, such as in-vitro fertilization. The major limitations of USG are its user dependency and equipment. Also, there are limitations in displaying a global view of the pelvis and large ovarian lesions. Magnetic resonance imaging (MRI), with its excellent soft-tissue contrast resolution and characteristics, is a useful non-invasive alternative modality to USG. Just one study evaluated MRI and revealed more small size antral follicles compared to 3D-USG. Study design, size, duration A prospective cross-sectional observational study was performed in an assisted reproduction techniques (ART) post-graduation program setting from an assisted reproductive center in Sao Paulo, Brazil, which ran throughout 2019–2020, with a total number of 59 patients that were in fertility treatment and needed to undergo to a MRI procedure to evaluate uterine or pelvic diseases as, Myoma, Adenomyosis, endometriosis, and adnexal cysts. Participants/materials, setting, methods Patients were evaluated to access the AFC by the MRI method and 2D transvaginal USG, and Anti-Mullerian Hormone (AMH) concentration to evaluate the ovarian reserve. Comparison between methods was done through Wilcoxon signed ranks test and Bland-Altman analysis. Ovarian reserve was classified as follows: very low (&amp;lt;4 follicles/AMH&amp;lt;0.5); low (5–7 follicles/AMH=0.5–1.1); normal (8–15 follicles/AMH=1.1–3.5); normal-high (&amp;gt;15 follicles/AMH&amp;gt;3.5). Weighted Cohen’s kappa was used to verify agreement between MRI, USG and AMH classifications of ovarian reserve. Main results and the role of chance Average AFC for USG were 5,55±4.01 for left ovary and 5.55±3.8 for right ovary. Average follicle count for both ovaries was 10±7.07. Regarding MRI, mean counts were 6.44±4.81 for left ovary, 5.65±3.85 for right ovary, and a 11.89±7.89 follicle sum mean count. Average concentration of AMH was 1.79±1.44. The Wilcoxon test and Bland-Altman analyses found differences and systematic biases for comparison between USG and MRI for both ovaries (–2.58; limits of agreement=–14.56 to 9.40, Wilcoxon p = 0,008) and for the right ovary (–1.48; limits of agreement=–8.32 to 5.35, Wilcoxon p = 0,031). There was no difference between methods for the left ovary. Weighted Cohen Kappa coefficients showed substantial agreement between ovarian reserve classifications based on AMH levels, USG, and MRI. The conducted paired comparisons were USG with MRI (k = 0.676), AMH with MRI (k = 0.760) and USG (k = 0.609). Limitations, reasons for caution The systematic biases found when comparing USG to MRI methods may suggest a consistent detection of more follicles with MRI procedures in comparison to the USG method. This bias found warrants caution as it must be confirmed, in future studies. Wider implications of the findings: The MRI method reveals similar ovarian reserve to USG when used the same classification, and a higher agreement to AMH. This suggests that MRI is a reliable method of quantifying antral follicles and can also be adopted when the patient will need to evaluate pelvic pathologies. Trial registration number Not applicable

Reconstructive Options for Tibial Bone Defects.

Segmental bone defects of the tibia are amenable to multiple treatment options including classic bone transport, shortening and then lengthening, induced membrane technique, transport over a nail, free fibular grafting, and medial transport of the ipsilateral fibula. These treatment options have relative advantages and disadvantages, depending on defect size, soft-tissue characteristics, the presence or absence of infection, and associated morbidity. Relatively, few large comparative studies exist, and surgeons are left to their own experience and the opinion of experts within the field to guide surgical decision-making.

Oromandibular reconstruction with double‐skin paddle fibular free flap: A systematic review and meta‐analysis

Reconstruction of complex head and neck defects is challenging, especially when more than one soft-tissue subunit is involved. The osteocutaneous fibular flap underwent continual evolution to improve its soft-tissue characteristics, such as including a second skin island. The purpose of this study was to evaluate outcomes regarding oromandibular reconstruction with a double-skin paddle fibular free flap (DSPFFF) using three different techniques: central de-epithelialized skin paddle, distally-based double-skin paddle (DSP), or proximally and distally-based DSP. A systematic review was performed in December 2020 using Pubmed and MedLine Ovid databases according to the PRISMA guidelines. A meta-analysis of functional outcome and complications was performed to estimate single incidence rates. A total of 449 patients were included, with a follow-up of 1-84 months, where 330 patients underwent reconstruction with the first technique, 23 patients with the second technique, and 96 patients with the third technique. The meta-analysis showed an overall good functional outcome and a low-complication rate for oromandibular reconstruction with DSPFFF. A better functional outcome and a lower complication rate were found when a distally-based DSPFFF was harvested compared to a proximally and distally-based DSPFFF. The DSPFFF was found to be useful and reliable for reconstructing composite and extensive head and neck defects, with an overall good functional outcome and a low-complication rate. The meta-analysis showed a better positive outcome on distally-based DSPFFF rather than proximally and distally-based DSPFFF. In addition, distally-based DSPFFF showed a lower complications rate when compared with proximally and distally-based DSPFFF.

Sodium Alginate Ultrasound Phantom for Medical Education.

The ultrasound phantoms used to educate medical students should not only closely mimic the ultrasound characteristics of human soft tissues but also be inexpensive and easy to manufacture. I have been studying handmade ultrasound phantoms and proposed an ultrasound phantom comprising calcium alginate hydrogel that met these requirements but caused a speckle pattern similar to that observed in ultrasound images of liver. In this study, I show that adding ethanol to the precursors used to fabricate the phantom reduces the speckle pattern. The ultrasound propagation velocity and attenuation coefficient of the phantom were 1561 ± 8 m/s and 0.54 ± 0.18 dB/cm/MHz, respectively (mean ± standard deviation), which are within the ranges of those in human soft tissues (1530-1600 m/s and 0.3-1.0 dB/cm/MHz, respectively). This phantom is easy to fabricate without special equipment, is inexpensive, and is suitable for elementary training on ultrasound diagnosis, operation of ultrasound-guided needles, and blind catheter insertion.

A Comparison of Craniofacial Characteristics between Two Different Adult Populations with Class II Malocclusion-A Cross-Sectional Retrospective Study.

Simple SummaryOne of the most common orthodontic problems, Class II malocclusion, may lead to an increased risk of dentoalveolar trauma, psychosocial issues, and a possible compromised quality of life. Oftentimes clinicians use normative standard values to which each patient is compared to identify deviations from the norm, in order to determine a patient-specific treatment plan. Large inter-individual and inter-ethnic variability, however, is sometimes not considered. In our study, we compared the cephalometric characteristics between two different ethnic groups (South Indian and Vietnamese) with the phenotype of Class II malocclusion in the hope of better understanding this variation and its implications in treatment planning to achieve satisfactory outcomes.The dental, skeletal, and soft-tissue characteristics of a particular malocclusion can differ based on ethnicity, race, age, sex and geographical location with Class II malocclusion being one of the most prevalent malocclusions encountered in orthodontic clinical practice. The broad understanding of the characteristics of vertical skeletal and dental parameters in patients with Class II malocclusion can help clinicians to identify patterns and variations in the expression of this phenotype for better treatment outcomes. Hence, we compared the craniofacial characteristics of skeletal and dental Class II malocclusion traits from Indian and Vietnamese individuals to analyze the vertical skeletal and dental patterns in both population groups. The sample comprised of lateral cephalograms from 100 young adults with Class II malocclusion, of which fifty (25 males and 25 females) were from South India and the other 50 age- and sex-matched adults from Vietnam. The lateral cephalometric radiographs were digitized into anonymous image files and were traced and assessed for 16 vertical skeletal and dental parameters. The ANB angle was greater in males (+1.4 deg; p < 0.001) and females (+1.9 deg; p < 0.001) in the South Indian population. The Vietnamese males had a larger mandibular plane angle, articular angle, anterior facial height and lower anterior facial height compared to the Indian males. The Vietnamese females had larger mandibular plane and articular angles compared to the Indian females. The skeletal class II malocclusion was more severe in the South Indian compared to the Vietnamese adults. The Vietnamese sample showed a generalized tendency towards a more vertical skeletal growth pattern and in males this pattern seemed to be due to the dentoalveolar component. The Vietnamese females showed a tendency towards a vertical growth pattern, but without apparent contribution by the dentoalveolar component.

Development of dentofacial characteristics related to Incontinentia Pigmenti syndrome: A repeated cross-sectional study

This research aimed to investigate the dentofacial characteristics of patients with Incontinentia Pigmenti (IP) (or Bloch-Sulzberger) syndrome in childhood, juvenile, and adulthood developmental stages. Fifteen female patients with a clinical diagnosis of IP, genetically confirmed by molecular testing, were included in this study. The records of 25 nonsyndromic females with Class I occlusion and lateral cephalograms obtained at similar developmental stages were selected from the American Association of Orthodontists Foundation Legacy Collection as a control group. Dentofacial features of subjects with IP and those in the control group were compared statistically using t test and Mann-Whitney rank-sum test (significance was defined as P<0.05). In general, patients with IP had shorter maxillary and mandibular length, straight skeletal profile, hypodivergent growth pattern with a tendency to mandibular protrusion, shorter anterior facial height, Class III compensatory positioning of incisors, more retruded lips, and smaller maxillary incisor exposure. The degree of hypodontia severity had a significant impact on skeletal, dental, and soft-tissue features in patients with IP. The results of this study showed that, since childhood, the dentofacial characteristics of patients with IP were progressively distancing from those of nonsyndromic patients with Class I occlusion, presenting their own orthodontic needs.

Comparative evaluation of Skeletal, Dental, and Soft Tissue Changes in Class II Division 1 Malocclusion Cases Treated with Twin Block and innovative Clear Block Appliance - A Prospective Interventional Study

The present study was undertaken to evaluate and compare the skeletal, dental, and soft tissue changes in skeletal Class II division 1 cases treated with Twin Block and Clear Block appliances using a cephalogram. A total of 40 patients of age between 12-14 years were randomly divided into two equal groups. Group 1: treated with Twin Block appliance and Group 2: treated with Clear Block appliance. The pre-treatment lateral cephalogram was taken and skeletal, dental, and soft tissue parameters were evaluated and the appliance was delivered. After 8 months, another lateral cephalogram of all the cases was taken and analyzed. The pre and post-treatment values were compared between the two groups. The pre-treatment cases were almost comparable in skeletal, dental, and soft tissue features in both groups. There was a significant change in mandibular growth by SNB angle. The retrusion and extrusion of maxillary incisors as well as a proclination and extrusion of mandibular incisors were seen in group 1 while no change was observed in group 2. Treatment with Clear Block appliances has shown significant and favorable Skeletal, Dental and Soft tissue changes which are similar to already proven by the Twin Block appliance. Clear Block provides an esthetic and less bulky option for growth modification with similar results as compared to conventional Twin Block with the additional benefit of preventing lower incisor proclination.

Correlation Between Gender and Soft Tissue Characteristics Of Face Among South Indian Population Of Various Skeletal Malocclusion

Correlation Between Gender and Soft Tissue Characteristics Of Face Among South Indian Population Of Various Skeletal Malocclusion

Two-dimensional viscoelastic imaging using an enhanced FDTD-AHI approach

Ultrasound viscoelastography is a quantitative and convenient imaging model that images soft tissues based on shear waves’ propagation. Thanks to the interaction between ultrasonic waves and shear waves, the physical features of soft tissues (elasticity, viscosity) are expressed by complex shear modulus (CSM) parameters, useful information for diagnosing tissue medical states. Therefore, this paper presented a new efficient approach to estimate CSM and reconstruct the viscoelastic images. This paper develops a two-dimensional shear wave propagation model applying finite difference time domain (FDTD) technique and then employing a proposed bandpass filter to reduce measured particle velocity noise of shear wave; finally, algebraic Helmholtz inversion (AHI) is utilized to estimate the CSM directly. As already known, excitation frequency for ultrasound viscoelastography system is a single one. In the previous research, the low pass filter is used to reduce frequency vibrations and measurement noise as well as fluctuations at low frequency; however, it is unable to completely eliminate noise since the measured particle velocity is affected by high-frequency noise and fluctuations in low frequency. Therefore, the enhanced FDTD-AHI algorithm applies a bandpass filter, which retains only the frequency band containing the excitation frequency, promising to eliminate low- and high-frequency noise. Moreover, we proposed to cut the transient part of the filtered signal to avoid affecting AHI step and thus to improve the CSM estimation. The simulation scenarios have proved the effectiveness of the enhanced FDTD-AHI algorithm. The proposed method’s normalized error is significantly reduced compared to the traditional manner using a low pass filter. We reconstructed two-dimensional images of elasticity and viscosity in the area of interest. The estimated quality near the excitation source is quite good. Still, far away from the excitation source, it is of low quality, and there are many large fluctuations due to the reduced shear wave and being much affected by noise. Another limitation of our proposed method is that it can reduce the additive noise in the lower and higher frequencies of the exciting one except the noise around this frequency. The shear wave propagation model using FDTD method provides high accuracy and low complexity compared to the finite element method (FEM). The absence of optimal or adapted filters in our approach can reduce the imaging system’s computational complexity.

A Novel Method to Make Polyacrylamide Gels with Mechanical Properties Resembling those of Biological Tissues

Studies characterizing how cells respond to the mechanical properties of their environment have been enabled by the use of soft elastomers and hydrogels as substrates for cell culture.A limitation of most such substrates is that, although their elastic properties can be accurately controlled, their viscous properties cannot, and cells respond to both elasticity and viscosity in the extracellular material to which they bind. Some approaches to endow soft substrates with viscosity as well as elasticity are based on coupling static and dynamic crosslinks in series within polymer networks or forming gels with a combination of sparse chemical crosslinks and steric entanglements. These materials form viscoelastic fluids that have revealed significant effects of viscous dissipation on cell function; however, they do not completely capture the mechanical features of soft solid tissues. In this report, we describe a method to make viscoelastic solids that more closely mimic some soft tissues using a combination of crosslinked networks and entrapped linear polymers.Both the elastic and viscous moduli of these substrates can be altered separately, and methods to attach cells to either the elastic or the viscous part of the network are described. Graphic abstract: Polyacrylamide gels with independently controlled elasticity and viscosity.

A study of dentofacial morphology in yemeni adults with normal occlusions a cross sectional prospective study

OBJECTIVE:The purpose of this study was to describe the dentofacial morphology of Yemeni adults.MATERIALS AND METHODS:The lateral cephalograms of 100 Yemeni adults (50 males, 50 females) were included in the study. All subjects were born to Yemeni parents and grandparents. They all had Class I occlusions with minor or no crowding, well-aligned upper and lower dental arches, good facial harmony, all teeth present except third molars, and no history of orthodontic therapy or maxillofacial surgery. Five angular and eighteen linear measurements were analyzed to determine the soft tissue, skeletal, and dental features. The differences for each measurement between Yemeni males and females were calculated using unpaired t–tests.RESULTS:Significant sexual and racial differences were found for three linear parameters in the skeletal analysis, one angle, and four linear dental measurements, and for all soft tissue linear parameters. Yemeni adults showed a tendency to a facial pattern of Class II, convex profile, reduced prominence of chin, increased lower facial height, and a clockwise rotation of the mandibular plane angle.CONCLUSION:Yemeni adults have different dentofacial parameters when compared to other racial standards, and these differences could aid in diagnosis and treatment planning.

The Structural Effects of Diabetes on Soft Tissues: A Systematic Review.

Hyperglycemia, which is associated with diabetes, increases the production of advanced glycation end products. Advanced glycation end products lead to the structural degradation of soft tissues. The structural degradation of diabetic soft tissues has been investigated in humans, rodents, and canines. Therefore, the objective of this review is to unify the various contributions to diabetes research through the mechanical properties and geometric characteristics of soft tissues. A systematic review was performed and identified the effects of diabetes on mechanical and geometric properties of soft tissues via experimental testing or in vivo - driven finite element analysis. The literature concludes that diabetes contributes to major structural changes in soft tissues but does not cause the same structural changes in all soft tissues (e.g., diabetic tendons are weaker and diabetic plantar tissues are tougher). Diabetes stiffens and toughens soft tissues, thus altering viscoelastic behavior (e.g., poor strain and stress response). However, diabetes management routines can prevent or minimize the effects of diabetes on the mechanical and geometric properties of soft tissues. Unification of the structural effects of diabetes on soft tissues will contribute to the pathophysiology of diabetes.

An Active Female Human Body Model for Simulation of Rear‐End Impact Scenarios

AbstractWhiplash associated disorder (WAD) is a type of injury caused by rear‐end impacts. It is a painful long‐term injury of the soft tissue in the neck, which women suffer from 1.5 to 3 times more often compared to men. Progress in WAD research is difficult, as (i) it occurs at a loading level where muscle activity can no longer be neglected, (ii) as soft tissue characteristics play an essential role in WAD and (iii) there is no consensus on the injury mechanism causing WAD. Therefore, computational models of the human body are the most promising method to advance the understanding of WAD. Here, improvements of boundary and initial conditions are presented together with a discussion of its effects on the head kinematics and neck load.

3D CT Soft Tissue Craniofacial Analysis and Lip Morphology

Objctive: To assess the soft tissue characteristics of Bangladeshi adults to formulate soft tissue 3D CT standards using Holdaway’s (HA) and lip morphology (LM) analyses. Another aim of this study was to assess the gender dimorphism of Bangladeshi population. Material and Methods: One hundred and seventeen (Eighty-five men and Thirty-two women) Bangladeshi adults have obtained their computed tomography (CT) scan at the Radiology Department for normal diagnosis. Craniofacial deformities were undetected in all cases. The CT images were prepared by a 3D imaging programming software (Mimics 11.02 Materialise). Parameters from the identified landmark points were measured in 3D through this software. Results: Upper lip thickness (ULT) (vermillion UL-A point) measurement was significant in HA and in LM analyses, upper lip protrusion (ULP) (Ls to Sn-SPog) measurement has demonstrated significant difference among both genders, where p-value was less than 0.05. Mean measurements of Bangladeshi adults were relatively comparable except the face convexity (FC) when compared with the HA cephalometric soft tissue values. Conclusion: By using HA and LM analyses, 3D CT soft tissue standards were established for Bangladeshi adults. Measurements for all parameters have remained equivalent with the HA standard data apart from the FC measurement. This consequently may demonstrate that the Bangladeshi population retains a convex shape with a slight protrusive lip or retruded chin.

A study to compare nasopharyngeal airway space in skeletal Class I, Class II, and Class III malocclusion

Background: Studies in the past have assessed relation between airway and type of malocclusion and found no association between rhinomanometric measures of airway adequacy and type of malocclusion or craniofacial morphology. Hence, the present study was undertaken to test whether there is any association between pharyngeal airway and type of malocclusion. Methodology: The subjects were divided into 3 groups based on skeletal pattern with 20 subjects in each group: Group 1 with Class I skeletal pattern, Group 2 with Class II skeletal pattern, and Group 3 with Class III skeletal pattern. All the cephalograms were taken in natural head position. Results: There is no significant difference found in total nasopharyngeal area between 3 groups. However, aerial area was significantly reduced in Group 3 (398.4 mm2) than that of Group 2 (485.737 mm2) (P = 0.012). Whereas, significant reduction in adenoidal area was observed in Group 2 (184.021 mm2) when compared with that of Group 3 (286.183 mm2). Conclusion: There was no statistically significant relationship between different skeletal groups and nasopharyngeal soft-tissue characteristics, except for two measurements i.e. aerial and adenoidal area of Group 2 and Group 3.

Correlation between gender and soft tissue characteristics of face among south Indian population of various skeletal malocclusion

Every face is unique and this variation also exists between genders. This forms the basis of sexual dimorphism. The aim of this study was to determine the correlation between gender and soft tissue of face among the south Indian population. The study sample comprised 30 lateral cephalograms collected between the time period of June 2019 - March 2020, which were divided into 3 groups. FACAD software was used for the analysis of lateral cephalograms to obtain six variables, namely: glabella area (G-G1), subnasal area (A-Sn), Upper lip thickness (J-Ls), Lower lip thickness (I-Li), Labiomental sulcus thickness (B-Sm), Chin area (Pg-Pg1). The obtained results were tabulated and statistically analysed using SPSS software version 23. One-way ANOVA and post hoc tests were performed between the skeletal malocclusions. Independent t-test was done to compare the variables between the two genders. The obtained results show a mean increase in all the variables of Class II except Lower lip thickness, which was maximum in Class I skeletal malocclusion. The results of One-way ANOVA, however, was statistically insignificant. Hence, soft tissue characteristics can provide vital information on sexual dimorphism and also aid in the diagnosis of various malocclusions in orthodontics.

Dosimetric impact of commercial CT metal artifact reduction algorithms and a novel in-house algorithm for proton therapy of head and neck cancer.

To compare the dosimetric impact of all major commercial vendors' metal artifact reduction (MAR) algorithms to one another, as well as to a novel in-house technique (AMPP) using an anthropomorphic head phantom. The phantom was an Alderson phantom, modified to allow for artifact-filled and baseline (no artifacts) computed tomography (CT) scans using teeth capsules made with metal amalgams or bone-equivalent materials. It also included a cylindrical insert that was accessible from the bottom of the neck and designed to introduce soft tissue features into the phantom that were used in the analysis. The phantom was scanned with the metal teeth in place using each respective vendor's MAR algorithm: OMAR (Philips), iMAR (Siemens), SEMAR (Canon), and SmartMAR (GE); the AMPP algorithm was designed in-house. Uncorrected and baseline (bone-equivalent teeth) image sets were also acquired using a Siemens scanner. Proton spot scanning treatment plans were designed on the baseline image set for five targets in the phantom. Once optimized, the proton beams were copied onto the different artifact-corrected image sets, with no reoptimization of the beams' parameters, to evaluate dose distribution differences in the different MAR-corrected and -uncorrected image sets. Dose distribution differences were evaluated by comparing dose-volume histogram (DVH) metrics, including planning target volume D95 and clinical target volume D99 coverages, V100, D0.03cc, and heterogeneity indexes, along with a qualitative and water equivalent thickness (WET) analysis. Uncorrected CT metal artifacts and commercial MAR algorithms negatively impacted the proton dose distributions of all five target shapes and locations in an inconsistent manner, sometimes overdosing by as much as 11.1% (D0.03) or underdosing by as much as 11.7% (V100) the planning target volumes. The AMPP-corrected images, however, provided dose distributions that consistently agreed with the baseline dose distribution. The dosimetry results also suggest that the commercial MAR algorithms' performances varied more with target location and less with target shape. Once relocated further from the metal, the target showed dose distributions that agreed more with the baseline for all commercial solutions, improving the overdosing by as much as 6%, implying inadequate HU correction from commercial MAR algorithms. In comparison to the baseline, HU profile shapes were considerably altered by commercial algorithms and reference values showed differences that represent stopping power percentage differences of 2.7-10%. The AMPP algorithm plans showed the smallest WET differences with the baseline (0.06cm on average), while the commercial image sets created differences that ranged from 0.11 to 0.54cm. Computed tomography metal artifacts negatively impacted proton dose distributions on all five targets analyzed. The commercial MAR solutions performed inconsistently throughout all targets compared to the metal-free baseline. A lack of CTV coverage and an increased number of hotspots were observed throughout all commercial solutions. Dose distribution errors were related to the proximity to the artifacts, demonstrating the inability of commercial techniques to adequately correct severe artifacts. In contrast, AMPP consistently showed dose distributions that best matched the baseline, likely because it makes use of accurate HU information, as opposed to interpolated data like commercial algorithms.

A novel simplified biomechanical assessment of the heel pad during foot plantarflexion.

The heel pad (HP) which is located below the calcaneus comprises a composition of morphometrical and morphological arrangements of soft tissues that are influenced by factors such as gender, age and obesity. It is well known that HP pain and Achilles tendonitis consist of discomfort, pain and swelling symptoms that usually develop from excessive physical activities such as walking, jumping and running. The purpose of this study was to develop biomechanical techniques to evaluate the function and characteristics of the HP. Ten healthy participants (five males and five females) participated in this laboratory-based study, each performing a two-footed heel raise to mimic the toe-off phase during human locomotion. Twenty-six (3 mm) retroreflective markers were attached to the left and right heels (thirteen markers on each heel). Kinematic data was captured using three-dimensional motion analysis cameras synchronised with force plates. Descriptive and multivariate statistical tests were used in this study. In addition, a biomechanical technique that utilises only six markers from 26 markers to assess HP deformation and function has been developed and used in this study. Overall HP displacement was significantly higher in males on the most lateral part of the right heel (p < 0.05). No significant differences were evident when comparing the non-dominant and dominant heels during the baseline, unloading and loading phases (p > 0.05). Findings from this study suggested that biomechanical outputs expressed as derivatives from tracked HP marker movements can morphologically and morphometrically characterise HP soft tissue deformation changes. The outcome of this study highlights the importance of 3D motion analysis being used as a potential prospective intervention to quantify the function / characteristics of the heel pad soft tissues.

Preliminary study on mechanical characteristics of maxillofacial soft and hard tissues for virtual surgery

PurposeVirtual surgery system can provide us a realistic and immersive training environment, in which haptic force-feedback gives operators ‘touching feeling.’ Appropriate deformation models of soft and hard tissues are required for the achievement of real-time haptic feedback. To improve accuracy of modeling and haptic feedback simulation for maxillofacial virtual surgery, mechanical characteristics of soft and hard tissues should be explored.MethodsCraniofacial soft tissues from one male and female cadavers were divided into two layers: skin and muscle. Maxillofacial tissues were divided into frontal, chin, temporalis, masseter regions. Insertion and cutting process were conducted using VMX42 5-axis linkage system and recorded by piezoelectric dynamometer. Maximum stiffness values were analyzed, and insertion curves before puncture were fitted using a polynomial model. Elasticity modulus and hardness of maxillofacial hard tissues were measured and analyzed using Berkovich nanoindentation.ResultsTissues in different maxillofacial regions, as well as from different layers (skin and muscle), displayed various mechanical performance. Maximum stiffness values and cutting force of soft tissues in male and female had significant difference. The third-order polynomial was demonstrated to fit the insertion curves well before puncture. Furthermore, elasticity modulus and hardness of enamel were significantly greater than that of zygoma, maxilla and mandible.ConclusionMechanical properties of hard tissues are relatively stable, which can be applied in virtual surgery system for physical model construction. Insertion model and cutting force for soft tissues are meaningful and applicable and can be utilized to promote the accuracy of response for haptic feedback sensations.