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Spinal dermoid cysts are relatively infrequent tumors generally associated with a benign course. Here we describe three cases and analyzed the 109 cases of lumbar dermal cysts described in the literature in the last 20 years. We report a pediatric patient with a dermoid cyst posterior to a lumbar surgery for myelomeningocele repair with bad evolution; and two adult patients with the affection of the motor and autonomic function with good surgical outcomes. In approximately half of the reviewed cases, it was reported at least one complication. In fact, two cases had a fatal outcome. We discuss relevant characteristics of these lesions and those aspects probably associated with complications and bad outcomes.

Objective: The aim of this study was to compare radiographically thermoplastic and conventional heat cured acrylic resin as denture base material for mandibular conventional type implant retained complete overdentures and evaluate the effect of this difference on the implants stability. Materials and methods: Fourteen edentulous patients were selected to construct two implants retained mandibular overdenture. The patients were equally divided into two groups according to material of denture base: group I, patients with thermoplastic resin constructed by injection moulding technique; and group II, patients with denture bases constructed by conventional heat curing acrylic resin. Radiographic and implant stability parameters were evaluated 1 year study. Results: There was no statistically significant difference between the thermoplastic and conventional heat cured denture bases for implant retained mandibular overdenture in bone resorption and stability of the implants. Conclusion: There was no statistically significant difference between the thermoplastic and conventional heat cured implant overdenture bases. Both denture bases have beneficial effect on implant osseointegration and stability.

Background Pediatric atlantoaxial instability (AAI) is not common and could be a serious clinical condition. The Goel-Harms technique is one of the most used techniques in adults and needs more evaluation in pediatric populations. This study reports the feasibility and safety of the Goel-Harms technique in the treatment of pediatric reducible AAI. Methods In this retrospective cohort study we reported all pediatric patients who underwent Goel-Harms technique for AAI with a minimum 1-year follow up. Patients were clinically assessed using the Japanese Orthopedic Association (JOA) score and radiologically with plain radiographs, computed tomography scan, and magnetic resonance imaging of the craniocervical region. Postoperatively, patients were followed up according to our clinical and radiographic imaging protocol. The following parameters were recorded: JOA score, construct stability, fusion, and abnormal events. Results A total of 25 patients have completed a 1-year follow-up and fulfilled our criteria. The mean age was 10.68 ± 4.47 (range, 3–17) years. Fifteen patients were male and 10 were female. The final diagnosis included Down syndrome (DS) in 8, type II dens fracture in 7, os odontoideum in 3, and atlantoaxial rotatory fixation in 7. The mean follow-up was 21.76 ± 8.22 months. The preoperative JOA score improved from 15.96 ± 1.46 to 16.76 ± 1.92 at the last follow-up. Sound bone fusion was reported in 92% of patients. Conclusions Our data suggest that the Goel-Harms technique is a safe, feasible, and effective procedure in managing pediatric reducible AAI. Special perioperative care should be offered to young AAI patients with DS.

Optic carotid and carotid oculomotor triangles are the main corridors for reaching sellar and parasellar lesions...

A fully heterogeneous population tumour control probability (TCP) model, based on the linear-quadratic (LQ) cell survival concept combined with the Poisson statistic, was established to predict local tumour control after one, two and three years. This TCP model was created using data from 16 publications that reported on early-stage non-small-cell lung cancer (NSCLC) treated using either three-dimensional conformal radiation therapy (3D-CRT), continuous hyperfractionated accelerated radiotherapy (CHART) or stereotactic ablative body radiotherapy (SABR). The TCP model was fitted to the clinical outcome data using optimised radiosensitivity values produced by the Nelder-Mead simplex algorithm. The statistical analysis resulted in R2 values of 0.96, 0.96 and 0.97 and wRMSE values of 3.9%, 5.2% and 5.9% for one-, two- and three-year local tumour control rates, respectively. The TCP models for one, two and three years were internally validated using a bootstrap resampling approach. The mean R2 and 95% CI for the bootstrap samples were 0.98 (0.93-0.99), 0.98 (0.95-0.99) and 0.98 (0.96-0.99) for the one-, two- and three-year local tumour control rates, respectively. Variations in the TCP with clonogenic density were then further investigated by introducing a new mathematical model to vary the clonogenic cell and radiation dose distribution across the treated volume. Based on the above model, it was estimated that 60% of the dose was sufficient to maintain the TCP after two years for the areas with lower clonogenic cell density. If externally validated, this lower-dose treatment plan could have beneficial effects on the surrounding healthy tissue without negatively affecting tumour control.

This study evaluated the effect of small systematic errors, such as those from a multileaf collimator (MLC), on the quality of intensity modulated radiotherapy (IMRT) treatment plan delivery. Two IMRT quality assurance (QA) verification techniques, field-by-field (FBF) and singe-gantry-angle composite (SGAC), were performed to evaluate both original and modified plans using a 2D ion chamber array detector. The dose distributions measured by the array detector for both FBF and SGAC were compared with the dose distribution calculated by the treatment planning system (TPS). FBF was found to be more sensitive than SGAC at detecting small systematic errors such as the opening and closing of the MLC’s segments, which were evaluated with respect to a gamma-index of 3%/3 mm and 2%/2 mm. The systematic errors involved in closing the segments of the anterior field by 2 mm and 3 mm showed a significant difference compared with the original field (unmodified): 83.1 ± 1.7% and 42.9 ± 1.9% gamma-index passing rates, respectively, for FBF. For SGAC, the magnitude of closing the MLC by 2 mm remained unnoticed and resulted in a 95.1 ± 2.61% gamma-index passing rate. Opening the MLC by 2 mm gave a false negative, but more than 5% of the rectum received 75 Gy, which exceeded the tolerance radiation dose recommended by the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC).

Established in 2002, this long running MSc in Medical Physics program was awarded CAMPEP accreditation in 2015, thus being one out of only two CAMPEP approved graduate programs outside North America. The program is a full-time, one-year taught master course delivered by a close university–hospital collaboration. This paper will give an outline of the current program structure and will identify challenges likely affecting the areas of teaching, research and course administration. Strategies to address these challenges will be discussed. Since the accreditation, the number of students enrolled in the program increased from 8 in 2015/16 and 16 in 2016/17 to 21 in 2017/18 and 25 in 2018/19. The number of non-EU students in these cohorts was 2, 5, 4, and 9 respectively. Non-EU students predominantly originate from North America and Saudi-Arabia. The total number of applicants averages at approximately 55 per year. A further increase in student intake has been advocated but might impact negatively on the quality of the clinical training which forms a vital part of the program. Students are given access to clinical systems for laboratory exercises as well as for pursuing research projects, thus gaining some clinical experience which will increase their employability. However, local clinical access has to be limited. In order to mitigate the situation, the program cooperates with medical physics departments nationwide and internationally. Curricular challenges arising from clinical implementations of ever-evolving technologies and from a rapidly changing medical physics landscape in general will be expanded on.

Several clinical situations call for the use of radiobiological principles as powerful clinical tools. The aim of this project is to examine the effect of radiotherapy dose intensity on local tumour control for non-small cell lung cancer (NSCLC) using the biological effective dose (BED) concept. A two-year tumour control probability (TCP) model was developed based on the linear-quadratic cell concept combined with Poisson statistics. The two-year local control outcome was analysed for the radiotherapy dose using the BEDs. The BED calculations and the TCP model were fitted to a series of NSCLC patients drawn from the literature. The investigation is based on the two-year local tumour control rate for stage I-II NSCLC for a dose fractionation size that varied from 1.5-20 Gy per fraction delivered via three radiotherapy treatments: 3D-conformal radiation therapy (3D-CRT), continuous hyperfractionated accelerated radiotherapy (CHART) and stereotactic ablative body radiotherapy (SABR). The BED values of 2,280 patients were computed and analysed as a function of local tumour control. To quantitatively assess the correlation between the BED and local tumour control, a residuals analysis and linear regression were performed. Higher radiotherapy doses were associated with improved local tumour control and survival rates for NSCLC, as suggested by the coefficient of the correlation R2 statistical test: 0.83 for the 3D-CRT and 0.91 for the SABR treatment.

Radiobiology has progressed sufficiently to provide suitable understanding of the radiation response of a wide spectrum of cell lines, and this principal provides a degree of certainty in the capability to describe this radiation response using mathematical models. The focus of this project was to examine the ability of a mechanistic Tumor Control Probability (TCP) model to predict treatment outcomes for a wide range of treatment strategies for Non-Small Cell Lung Cancer (NSCLC), such as hypo-fractionation, standard fractionation, and hyper-fractionation. A fully heterogeneous population-averaged TCP model was fit to clinical outcome data accumulated from the literature for NSCLC using optimized radiosensitivity values produced by the simplex algorithm. The clinical data reported the two-year local tumor control rate for Stage I–II NSCLC for dose prescription varies between 1.5–15 Gy per fraction. The biological parameters α, β, σα, and σβ were obtained with the simplex algorithm’s search of the radiosensitivity solution space of the outcome data described above. These values were obtained through a robust fitting procedure using the simplex algorithm based on the best available clinical data for dose response, total initial clonogen number, clonogen density, clonogen distribution, and hypoxia status of the average in NSCLC patients. The TCP model achieves an excellent level of fit, R2value of 0.92, and RMSE of 2.4% for the clinical outcome data for hyper, standard, and hypofractionated treatments using realistic values for biological input parameters. Residuals ⩽3% are produced by the TCP model when compared to clinical outcome data for both standard fractionation and SABR.