Beam Orientation Selection in Radiotherapy Treatment Planning

Op de afdeling radiotherapie van het Erasmus MC is een computermodel ontwikkeld waarmee in heel korte tijd de richting en de intensiteit van de bundels voor de bestraling van een patiënt kunnen worden bepaald

Beam Orientation Optimization for Intensity Modulated Radiation Therapy using Adaptive l1 Minimization

Beam orientation optimization (BOO) is a key component in the process of IMRT treatment planning. It determines to what degree one can achieve a good treatment plan quality in the subsequent plan optimization process. In this paper, we have developed a BOO algorithm via adaptive l_1 minimization. Specifically, we introduce a sparsity energy function term into our model which contains weighting factors for each beam angle adaptively adjusted during the optimization process. Such an energy term favors small number of beam angles. By optimizing a total energy function containing a dosimetric term and the sparsity term, we are able to identify the unimportant beam angles and gradually remove them without largely sacrificing the dosimetric objective. In one typical prostate case, the convergence property of our algorithm, as well as the how the beam angles are selected during the optimization process, is demonstrated. Fluence map optimization (FMO) is then performed based on the optimized beam angles. The resulted plan quality is presented and found to be better than that obtained from unoptimized (equiangular) beam orientations. We have further systematically validated our algorithm in the contexts of 5-9 coplanar beams for 5 prostate cases and 1 head and neck case. For each case, the final FMO objective function value is used to compare the optimized beam orientations and the equiangular ones. It is found that, our BOO algorithm can lead to beam configurations which attain lower FMO objective function values than corresponding equiangular cases, indicating the effectiveness of our BOO algorithm.Comment: 19 pages, 2 tables, and 5 figure

Personality factors and cognitive functioning in patients with somatic symptom and related disorders

Objective Somatic symptom and related disorders (SSRD) are often complicated by cognitive symptoms, including reduced information processing speed, memory, and planning. Depression has been related to poor cognitive functioning in SSRD, but the role of underlying personality factors is poorly understood. This study investigates the association between personality factors (neuroticism, extraversion, openness, agreeableness, and conscientiousness) with cognitive functioning in patients with SSRD. Methods Data from 366 patients with SSRD from a tertiary care expert center (mean age = 42.1 years (SD = 13.4), 59.6% women) were analyzed using a cross-sectional design. Neuropsychological assessments included measures of information processing speed, memory, attention, and executive function. Personality factors were assessed using the NEO-FFI and depressive symptoms using the PHQ-9. Results Regression analyses showed associations between neuroticism with poorer performance on visual memory (B = −0.09, SE = 0.04, β = −0.14, p = .019), and planning (B = −0.09. SE = 0.02, β = −0.23, p < .001). Extraversion was also inversely associated with visual memory (B = −0.13, SE = 0.05, β = −0.18, p = .011) and planning (B = −0.07, SE = 0.03, β = −0.17, p = .021) and openness was associated with better visual memory (B = 0.17, SE = 0.05, β = 0.19, p = .002). These associations were attenuated but remained significant after adjusting for depressive symptoms. Conclusion Neuroticism, extraversion, and low openness were associated with lower cognitive functioning (particularly planning and visual memory) in patients with SSRD, which remained significant after taking depressive symptoms into account

Patient-reported outcomes in patients with vitreous floaters:A systematic literature review

Seeking treatment for bothersome vitreous floaters is patient driven. To measure the impact of floaters and treatment on an individual's quality of life, patient-reported outcome measurements (PROMs) are essential. We review all studies using a PROM for patients with floaters. We evaluated content coverage against quality-of-life domains previously identified in other ophthalmic disorders, and against a qualitative study investigating quality-of-life issues in patients with floaters. We assessed measurement properties of PROMs using an extensive range of psychometric quality criteria. We identified 59 studies using 28 different PROMs. Many PROMs were not specifically developed for patients with floaters. Floater-specific PROMs were mostly based on content validation from an ophthalmologist or researcher perspective; two included a patient perspective. Using the outcomes of the qualitative study, we found that the floater-specific PROMs were narrow in their content coverage, with most items relating to visual symptoms and activity limitations. Testing the psychometric quality of PROMs was rare, and when employed mostly limited to responsiveness and known group validity. The remarkable high number of floater-specific PROMs reveals a need for such measurements in ophthalmology. Unfortunately, reporting on psychometric quality is limited, and content development is most often done without patient involvement.</p