Relationships between oxygen uptake, dynamic body acceleration and heart rate in humans.

AIM: Accurate estimation of energy expenditure (EE) is important in human and animal behavior analysis. Rate of oxygen consumption (VO2) reflects EE during aerobic metabolism but is not always convenient. Alternative methods include heart rate (HR) and overall dynamic body acceleration (ODBA). A favorable ODBA-VO2 relationship was recently reported but the strength of association between VO2, ODBA, HR and its variability (HRV) is less clear. METHOD: Fifteen young (23±4 years) healthy males of similar aerobic fitness (maximal oxygen uptake, VO2max=49.7±8.5 mL·kg(-1)·min(-1)) carried out progressive maximal exercise. ODBA, HRV and V̇O2 were recorded continuously. Relationships between ODBA, HRV and V̇O2 were explored using regression methods. RESULTS: VO2 was strongly related to ODBA and RR during walking (R=0.45,0.30; P<5x10(-5)) and running (R=0.60,0.38; P<5x10(-5)). HRV was related to VO2 during walking only (R=0.11-0.26; 0.005

Patient-related pitfalls and artifacts in nuclear medicine imaging.

Quality control in nuclear medicine is all important. This applies not only to preparation of the patient and acquisition of the image, but also to interpretation of the study. Although it may seem self-evident, it is important to remain aware of artifacts that are directly related to the patient and need special consideration. Furthermore, at times the distinction between normal variants and artifacts can be difficult. Commonly encountered patient-related artifacts include artifacts caused by attenuation, contamination artifacts, and artifacts caused by intravenous lines, tubes, and catheters. Less commonly, artifacts arise because of the use of multiple isotopes, the presence of fistulas or surgically altered anatomy, and pharmaceuticals and other substances interfering with expected radiopharmaceutical uptake and distribution. The diagnostic accuracy of nuclear medicine reporting can be improved by awareness of these patient-related artifacts. Both awareness and experience are also important when it comes to detecting and identifying normal (and abnormal) variants.

Low dose rate teletherapy using a telecaesium 137 unit radiobiological, physical and clinical considerations.

Low dose rate teletherapy aims to combine the supposedly superior results obtained with low dose rate implants with the convenience and staff protection characteristics of external beam therapy. Previous investigators have used telecobalt units to produce dose rates of 1.1 to 1.8 Gy/hr to treat in daily sessions lasting 6-10 hours to total doses of 60-70 Gy. These studies have not discounted the possibility that much of the advantage of interstitial implants results from the low dose rates used per se, and from the fact that the total dose is delivered in a short overall time. The relationship between total dose, dose rate and volume giving normal tissue and anit-tumour effects, however, remains ill-defined. At the Newcastle Mater Misericordiae Hospital a Caesium teletherapy unit has been modified to treat at low dose rates and a study has been designed with a view to establish which permutations of total dose and dose rate are isoeffective for acute mucosal and acute skin reactions in the dose rate range between 0.8 and 9.6 Gy/hr (1.3 and 16 cGy/min).