Comparison of positron emission tomography (PET) and computed tomography (CT) for better target volume definition in radiation therapy planning.

BACKGROUND: In cancer patients, positron emission tomography/ computed tomography (PET/CT) fused images present less variability in target contouring, respect to use only CT images, respectively. However, the gold standard has not yet been clearly established between radiation oncologists with regard to PET images and the methodology of contouring targets with confidence using PET/CT fused images. The aim of this study was to determine whether integrated PET/CT fused images provide advantages in virtual simulation compared with morphological contouring only with CT. MATERIAL AND METHODS: Thirty cancer patients were evaluated in an adapted PET/CT hybrid in radiotherapy (RT) setup position, with 20 of them being suitable for RT: 17 were suitable for curative intent, which was the group of interest in this study. All image series were sent to the RT work station (WS) where CT and PET series were automatically fused by Digital Imaging and Communications in Medicine (DICOM) in each case. PET series were threshold and were subjected to source-to-background contrast algorithms to fi nally redefine the original tumour description. Three different radiotherapy plans (RTP) for each patient were compared after targets were contoured: [1] planning over metabolic (PET) contoured targets, [2] planning over only morphologic (CT) targets, and [3] planning over targets obtained for treatment based on fused PET/CT images. RESULTS: PET/CT findings altered initial-stage planning in four patients (23.5%) because they had been undergoing chemotherapy. Gross target volume (GTV) and planning target volume (PTV) based only on PET showed more homogeneity to obtain mean doses (p = 0.025) with respect to those based on PET/CT, respectively. However, no percentage differences were observed in median PTV doses between the planning methods, although there was higher variability in PET/CT planning. Morphological (CT) and PET/ CT target volumes were more voluminous than metabolic (PET) volumes. On the other hand, 20% of metabolic (PET) PTV were out of those defined by PET/CT. Thoracic RT plans based on PET preserved better bilateral lung [percentage volume of lung irradiated with a dose of 20 Gy (V20); significance, R(2) = 0.559, p = 0.006]. CONCLUSIONS: For our physicians, PET/CT fused images allowed better contouring of primary tumours in 40% of head and neck cancers and 34% of thoracic cancers. PET/CT provides useful information for virtual simulation therapy. Image treatment and planning in an RT workstation is mandatory.

Use of an electron spoiler for radiation treatment of surface skin diseases.

OBJECTIVES: Low-energy electron beams are characterised by low surface doses with a pronounced dose build-up and penetration of several centimetres, but often a higher surface dose and a lower penetration range is desired. The purpose of this study was to investigate the use of an electron spoiler to modify these beams for treating surface skin diseases and evaluate the feasibility of this method. MATERIALS AND METHODS: An aluminium foil 4-mm thick covering the end of the electron applicator was used as a spoiler for a 6 MeV electron beam. The dosimetric characteristics of this beam were measured, and Monte Carlo simulations were performed. RESULTS: The spoiler reduced the practical range and increased surface and build-up doses, but it also significantly broadened the penumbra and increased peripheral doses. Nevertheless, the beam was clinically acceptable when skin collimation with lead was employed. Monte Carlo simulations agreed well with all the experimental measurements. CONCLUSIONS: The feasibility of using a low-energy electron beam with a spoiler for treating surface skin diseases was demonstrated. The method is hygienic and avoids some of the disadvantages associated with the bolus technique, but it is valid only for flat surfaces and perpendicular incidence. As a consequence, it can be an alternative to bolus and other reported methods in certain cases, especially when a particular sterility assurance level is required.

Prevalence and risk factors of suspected elder abuse subtypes in people aged 75 and older.

OBJECTIVES: To assess the prevalence of suspected elder abuse subtypes and to identify related factors. DESIGN: Cross-sectional, population-based, descriptive study. SETTING: Eight rural villages in Girona, Spain. PARTICIPANTS: Six hundred seventy-six inhabitants aged 75 and older. MEASUREMENTS: All participants were interviewed in their homes using the study protocol, which includes an abuse screen used in previous elder abuse studies and questions about demographic, social, physical, psychiatric, cognitive, and social services variables. RESULTS: The mean age of the participants was 81.7 +/- 4.8; 58.2% were female. Prevalence of suspected neglect abuse was 16.0% (95% confidence interval (CI)=13.2-18.9), prevalence of psychosocial abuse was 15.2% (95% CI=12.8-18.2), prevalence of financial abuse was 4.7% (95% CI=3.0-6.4) and prevalence of physical abuse was 0.1% (95% CI=0.004-0.8). Psychosocial abuse was positively associated with depressive symptoms (odds ratio (OR)=1.65, 95% CI=1.01-2.72), social isolation (OR=0.35, 95% CI=0.18-0.69), and frequent bladder incontinence (OR=2.44, 95% CI=1.23-4.86). Neglect abuse was positively associated with social isolation (OR=0.52, 95% CI=0.27-0.99), use of social services (OR=1.83, 95% CI=1.05-3.20), and living arrangements (OR=5.29, 95% CI=2.65-10.56). Financial abuse was associated with marital status (OR=0.15, 95% CI=0.04-0.59), age 85 and older, (OR=3.84, 95% CI=1.70-8.68), and Mini-Mental State Examination score (OR=0.85, 95% CI=0.78-0.94). CONCLUSION: After adjustment for confounding factors, each subtype of suspected elder abuse was associated with different variables. The results of this study suggest that elder abuse cannot be analyzed as a unitary concept and that risk factors must be assessed for each abuse subtype.