phosphorus-radioisotopes and Peripheral-Vascular-Diseases

To determine dosimetric parameters, such as radial and longitudinal dose profiles, for beta and gamma devices in peripheral endovascular brachytherapy.. An (192)Ir high-dose rate stepping source, a (90)Sr source train, and a (32)P-coated radiation balloon were investigated. The treatment-planning software PLATO, Monte Carlo code EGSnrc, and GafChromic film dosimetry were used to analyze the dose distribution of these devices.. For a 5-mm-diameter vessel, the ratio between the dose at 2 mm depth and the dose at the lumen surface was 1.8, 3.4, and 16.2 for the (192)Ir, (90)Sr, and (32)P devices, respectively. The dose variation at the reference depth of 2 mm into the vessel wall was 7-18 Gy, for different analyzed dose prescriptions. The reference lumen dose was different by a factor >8. For all three devices, the reference isodose length was not <5 mm on the proximal and distal edge of the active source length.. A complete set of dose parameters for beta and gamma sources has to be considered for appropriate treatment planning and performance, including reporting of reference depth dose, reference lumen dose, and reference isodose length.

Topics: Arteries; Brachytherapy; Film Dosimetry; Iridium Radioisotopes; Peripheral Vascular Diseases; Phosphorus Radioisotopes; Radiation Dosage; Strontium Radioisotopes

1. We set out to define abnormalities of oxidative ATP synthesis, cellular proton efflux and the efficiency of ATP usage in gastrocnemius muscle of patients with claudication due to peripheral vascular disease, using data obtained by 31P magnetic resonance spectroscopy during aerobic exercise and recovery. 2. Eleven patients with moderate claudication were studied and results were compared with 25 age-matched control subjects. Changes in pH and phosphocreatine concentration during recovery were used to calculate the maximum rate of oxidative ATP synthesis (Qmax.) and the capacity of net proton efflux. Changes in pH and phosphocreatine concentration were used to estimate rates of non-oxidative and (indirectly) oxidative ATP synthesis throughout exercise, taking account of abnormalities in proton efflux during exercise. 3. In patients with claudication, slow post-exercise phosphocreatine recovery showed a 42 +/- 9% decrease in Qmax., and the slow ADP recovery was consistent with this. pH recovery was slow, showing a 77 +/- 9% decrease in the capacity for proton efflux. Both abnormalities are compatible with a substantial reduction in muscle blood flow. 4. During exercise, increased phosphocreatine depletion and intracellular acidification were a consequence of impaired oxidative ATP synthesis and the consequent increase in non-oxidative ATP synthesis, compounded by reduced proton efflux. The acidification prevented an increase in ADP concentration which could otherwise partially compensate for the oxidative defect. All these abnormalities are compatible with a reduced muscle blood flow. 5. In addition, initial-exercise changes in pH and phosphocreatine concentration implied a 44 +/- 5% reduction in 'effective muscle mass', necessitating an ATP turnover (per litre of muscle water) twice as high for given power output as in control muscle. Some of this is probably due to a localized loss of muscle fibres, but the rest appears to reflect reduced metabolic efficiency of the muscle. This is not a direct consequence of reduced blood flow, and may be related to change in muscle fibre type.

Topics: Adenosine Triphosphate; Adult; Aged; Aged, 80 and over; Case-Control Studies; Female; Glycogen; Humans; Intermittent Claudication; Magnetic Resonance Spectroscopy; Male; Middle Aged; Mitochondria, Muscle; Muscle, Skeletal; Peripheral Vascular Diseases; Phosphorus Radioisotopes

Topics: Humans; Peripheral Vascular Diseases; Phosphorus; Phosphorus Radioisotopes; Polycythemia Vera; Vascular Diseases

Topics: Blood Vessels; Isotopes; Peripheral Vascular Diseases; Phosphorus; Phosphorus Radioisotopes; Phosphorus, Dietary; Radioactivity; Radioisotopes; Tolazoline