Direct aperture optimization for online adaptive radiation therapy

This paper is the first investigation of using direct aperture optimization (DAO) for online adaptive radiation therapy (ART). A geometrical model representing the anatomy of a typical prostate case was created. To simulate interfractional deformations, four different anatomical deformations were created by systematically deforming the original anatomy by various amounts (0.25, 0.50, 0.75, and 1.00 cm). We describe a series of techniques where the original treatment plan was adapted in order to correct for the deterioration of dose distribution quality caused by the anatomical deformations. We found that the average time needed to adapt the original plan to arrive at a clinically acceptable plan is roughly half of the time needed for a complete plan regeneration, for all four anatomical deformations. Furthermore, through modification of the DAO algorithm the optimization search space was reduced and the plan adaptation was significantly accelerated. For the first anatomical deformation (0.25 cm), the plan adaptation was six times more efficient than the complete plan regeneration. For the 0.50 and 0.75 cm deformations, the optimization efficiency was increased by a factor of roughly 3 compared to the complete plan regeneration. However, for the anatomical deformation of 1.00 cm, the reduction of the optimization search space during plan adaptation did not result in any efficiency improvement over the original (nonmodified) plan adaptation. The anatomical deformation of 1.00 cm demonstrates the limit of this approach. We propose an innovative approach to online ART in which the plan adaptation and radiation delivery are merged together and performed concurrently-adaptive radiation delivery (ARD). A fundamental advantage of ARD is the fact that radiation delivery can start almost immediately after image acquisition and evaluation. Most of the original plan adaptation is done during the radiation delivery, so the time spent adapting the original plan does not increase the overall time the patient has to spend on the treatment couch. As a consequence, the effective time allotted for plan adaptation is drastically reduced. For the 0.25, 0.5, and 0.75 cm anatomical deformations, the treatment time was increased by only 2, 4, and 6 s, respectively, as compared to no plan adaptation. For the anatomical deformation of 1.0 cm the time increase was substantially larger. The anatomical deformation of 1.0 cm represents an extreme case, which is rarely observed for the prostate, and again demonstrates the limit of this approach. ARD shows great potential for an online adaptive method with minimal extension of treatment time.     

Prevalence of G-6-PD deficiency in the Croatian Adriatic Coast population

BACKGROUND: The objective of this study was to determine the prevalence of glucose-6-phosphate dehydrogenase (G-6-PD) deficiency among the population of the Croatian Adriatic Coast, part of the Mediterranean basin. METHODS: The fluorescent spot test was used to screen 2,726 randomly selected high school students in the Croatian Adriatic coastal area. Fluorescence readings were performed at the beginning and at 3, 6, 10, and 25 min of incubation. Results were classified into the following three groups: bright fluorescence (BF), weak fluorescence (WF), and no fluorescence (NF). All NF and WF samples at 3 min were quantitatively measured using the spectrophotometric method. RESULTS: Twelve persons, 10 boys and 2 girls, were found to be deficient in G-6-PD, rendering a 0.44% prevalence of G-6-PD deficiency. All NF samples at fluorescent spot test were G-6-PD-deficient. WF at 3 min of the incubation period was present in 33 (1.2%) subjects, and only 2 (6%) were true positive. Fluorescence reading at 10 min of incubation omits five (41%) of the G-6-PD deficient samples. CONCLUSIONS: Prevalence of G-6-PD deficiency in the Croatian Adriatic coastal population is 0.44%. Fluorescent spot test for moderate enzyme deficiency is reliable in early fluorescence reading.     

Osteoporosis in anorexia nervosa: the influence of peak bone density, bone loss, oral contraceptive use, and exercise.

Anorexia nervosa occurs early in life and predisposes to osteoporosis. Exercise may be protective. We asked: (1) Does failure to attain peak bone density contribute to the deficit in bone density? (2) Does oral contraceptive use protect against osteoporosis? (3) Is any protective effect of exercise confined to weight-bearing sites? Areal bone density (g/cm2) and body composition were measured by dual x-ray absorptiometry in 65 patients with anorexia nervosa and 52 controls. Comparing the 12 patients with primary amenorrhea and the 37 patients with secondary amenorrhea, bone density (mean +/- SEM) at the lumbar spine was 0.88 +/- 0.04 versus 1.06 +/- 0.03 (P = 0.001), respectively. Bone density at the femoral neck was 0.80 +/- 0.04 versus 0.92 +/- 0.03 (P < 0.05), respectively. These values differed before, but not after, adjusting for the respective duration of illness (73.0 +/- 10.3 versus 34.1 +/- 4.8 months, P < 0.001) and fat-free mass (31.6 +/- 1.3 versus 35.4 +/- 0.5 kg, P < 0.01). Bone density at the lumbar spine in the 16 patients with 31.8 +/- 8.3 months of contraceptive exposure was higher than in the 49 patients with no contraceptive exposure (1.14 +/- 0.05 versus 1.02 +/- 0.02 P < 0.02) but was lower than in controls (1.14 +/- 0.05 versus 1.27 +/- 1.02, P < 0.01). No protective effect of contraceptive exposure was detectable at the femoral neck.(ABSTRACT TRUNCATED AT 250 WORDS)     

188. Urologische Komplikationen beim Morbus Crohn

Zusammenfassung Die enge topographische Nachbarschaft von Ileocoecalbzw. Sigmaregion mit Harnheiter und Harnblase und die spezifischen Eigenschaften des Morbus Crohn verursachen Komplikationen wie enterovesicale Fisteln oder obstruktive Ureteropathie mit Hydronephrosenbildung. In einem Krankengut von 73 Patienten mit Morbus Crohn trat eine entero-vesicale Fistel in 4 Fällen auf (5%). 114 ähnliche Mitteilungen liegen im Weltschrifttum vor. Resektion en bloo mit Verschluß der Fistel ist die Methode der Wahl. Bei 4 Patienten fand sich eine obstruktive Ureteropathie, die in 3 Fällen durch einfache Ureterfreilegung und in 1 Fahl durch eine Ureter-Reimplantation erfolgreich behandelt werden konnte. Es empfiehlt sich eine präoperative Ureterschienung. Beide Krankheitsbilder gehören der Spätphase des Morbus Crohn an.

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Urological complications of Crohn's disease

Summary The close topographic relationship of the ileocoecal and sigmoid regions to the ureter and urinary bladder and the specific properties of Crohn's disease cause complications such as enterovesical fistula or obstructive ureteropathy with hydronephrosis. Of 73 patients with Crohn's disease, 4 had an enterovesical fistula (5%). 114 similar observations are know from the world literature. En-bloc resection with closure of the fistula is the surgical treatment of choice. 4 patients had an obstructive ureteropathy which was successfully treated by simple desobliteration and/or ureter reimplantation (1 case). Preoperative catheterization of the urethers is strongly recommended. Both complications belong to the late stage in the course of the disease.

     

Geometric parameter analysis to predetermine optimal radiosurgery technique for the treatment of arteriovenous malformation

PURPOSE: To develop a method of predicting the values of dose distribution parameters of different radiosurgery techniques for treatment of arteriovenous malformation (AVM) based on internal geometric parameters. METHODS AND MATERIALS: For each of 18 previously treated AVM patients, four treatment plans were created: circular collimator arcs, dynamic conformal arcs, fixed conformal fields, and intensity-modulated radiosurgery. An algorithm was developed to characterize the target and critical structure shape complexity and the position of the critical structures with respect to the target. Multiple regression was employed to establish the correlation between the internal geometric parameters and the dose distribution for different treatment techniques. The results from the model were applied to predict the dosimetric outcomes of different radiosurgery techniques and select the optimal radiosurgery technique for a number of AVM patients. RESULTS: Several internal geometric parameters showing statistically significant correlation (p < 0.05) with the treatment planning results for each technique were identified. The target volume and the average minimum distance between the target and the critical structures were the most effective predictors for normal tissue dose distribution. The structure overlap volume with the target and the mean distance between the target and the critical structure were the most effective predictors for critical structure dose distribution. The predicted values of dose distribution parameters of different radiosurgery techniques were in close agreement with the original data. CONCLUSIONS: A statistical model has been described that successfully predicts the values of dose distribution parameters of different radiosurgery techniques and may be used to predetermine the optimal technique on a patient-to-patient basis.     

Interprofessional pharmacotherapy workshop: intervention to improve health professionals’ and students’ attitudes towards collaboration between physicians and pharmacists

ABSTRACT

Collaboration between physicians and pharmacists is recognized as an important factor for reducing medication errors and improving patient outcomes. Therefore, two pharmacotherapy workshops were delivered in Croatia - one for pre-registration medical (n=42, 4th-6th year) and pharmacy (n=38, 4th-5th year) students, and the other one for physicians (n=18) and pharmacists (n=23). The purpose of this study was to determine whether participation in common pharmacotherapy workshop could improve attitudes among participants towards interprofessional collaboration between pharmacists and physicians. Attitudes were measured by validated questionnaire “Scale of Attitudes Towards Collaboration Between Pharmacists and Physicians” at the beginning and at the end of the workshops. Three complex clinical scenarios were presented during the workshops. Participants were given general information about cases (all participants) and 2 groups of specific information (only for medical students/physicians and only for pharmacy students/pharmacists). For the first scenario, medical and pharmacy students/professionals were not allowed to exchange their specific information. However, participants collaborated for the 2nd and 3rd scenarios in order to achieve the hypothesized therapeutic goals. Before the workshops, pharmacists and pharmacy students showed more positive attitudes than physicians and medical students. However, the workshop contributed in closing the gap by equating health care professionals’ attitudes. Additionally, students’ attitudes were more positive after the workshop with an increase of 10% for medical and 2.2% for pharmacy students. This study indicates that interprofessional pharmacotherapy workshops could significantly improve attitudes toward collaboration between physicians and pharmacists for both students and practicing professionals.     

How health care professionals confront and solve ethical dilemmas – a tale of two countries: Slovenia and Croatia

AimTo assess the differences in the way how Slovenian and Croatian health care professionals (HCPs) confront ethical dilemmas and perceive the role of hospital ethics committees (HECs).MethodsThis cross-sectional, survey-based study involved HCPs from three Slovenian and five Croatian university medical centers (UMC). The final sample sizes were 308 (244 or 79.2% women) for Slovenia and 485 (398 or 82.1% women) for Croatia.ResultsCompared with Croatian physicians, Slovenian physicians reported a higher share of ethical dilemmas regarding waiting periods for diagnostics or treatment, suboptimal working conditions due to interpersonal relationships in the ward, and end-of-life treatment withdrawal, and a lower share regarding access to palliative care and patient information protection. Compared with Croatian nurses, Slovenian nurses reported a lower share of ethical dilemmas regarding the distribution of limited resources, recognizing the patient’s best interests, and access to palliative care. Compared with Croatian other HCPs, Slovenian other HCPs reported a lower burden of ethical dilemmas regarding waiting periods for diagnostics or treatment, distribution of limited resources, and access to palliative care. When encountering an ethical dilemma, all HCPs in both countries would first consult their colleagues. Slovenian and Croatian HCPs recognized the importance of the HECs to a similar extent, but viewed their role differently.ConclusionCroatian and Slovenian HCPs are confronted with different ethical dilemmas and perceive the role of HECs differently.

An ethical dilemma arises when we are confronted with a situation with two morally justifiable solutions, none of which is entirely satisfactory (1). In the course of their daily work, health care professionals (HCPs) encounter a broad range of ethical dilemmas (2-4), which often result in a moral distress for HCPs (5,6). A critical requirement for a successful response to an ethical dilemma is a strong foundation in medical professionalism cultivated during medical training and consolidated during professional work experience and career development (7-9).Slovenia and Croatia, previously the westernmost republics of the former Yugoslavia and now European Union members, share the same historical, geopolitical, economic, and religious background. A recent survey in the largest Slovenian tertiary hospital, the University Medical Center Ljubljana, found that the most important contexts that give rise to ethical dilemmas among HCPs were waiting periods for diagnostics and treatment, suboptimal working conditions due to poor interpersonal relationships, and preserving patients'' dignity, while the least important contexts were biomedical research, organ transplantation, and vaccine hesitancy (10). A study at the University Medical Center Rijeka found similar main ethical dilemmas in Croatian nurses and physicians, which included limiting life-sustaining therapy, euthanasia, and physician-assisted suicide (11).Except these two studies, little to nothing is known about the ethical dilemmas of HCPs in Slovenia and Croatia. In response to this limited evidence, we conducted a prospective survey with a primary objective to assess the differences in the share of ethical dilemmas among different categories of HCPs (physicians, nurses, and other HCPs) in Slovenian and Croatian tertiary hospitals (university medical centers, UMCs). The UMCs were purposively selected because in this kind of hospitals, one encounters complicated cases usually referred from other health care institutions for complex diagnostic and therapeutic procedures, which can often raise ethical issues. The secondary objectives of our survey were to study differences in the opinion on the existence of standard procedures when HCPs are facing an ethical dilemma; to determine whom HCPs consult when facing an ethical dilemma; and to identify the opinion on the importance of hospital ethics committees (HECs) and their role in Slovenia and Croatia.