George P. Vose

Estimation of Changes in Bone Calcium Content by Radiographic Densitometry

A point of conflict often arises when investigators of calcium mobility (as determined by metabolic balance studies) meet with investigators of radiographic bone densitometry (1–6). This is the apparent inability to explain the magnitude of change sometimes observed by densitometry with that thought physiologically possible by proponents of metabolic balance technics. The opinion has often been expressed that changes detectable by quantitative x-ray densitometry are unexplainable on the basis of metabolic balance studies in which a daily negative calcium balance on the order of 500 mg is considered to be high while 500 mg of calcium represents only 0.03 per cent of the entire skeleton. How then can reported changes in radiographic density on the order of 5 to 10 per cent within a single bone (7) be explained on the basis of metabolic balance studies? The described investigation was carried out in an attempt to reconcile the apparent discrepancies between the two methods of measuring bone turnover rate. Th...

Radiographic Determination of the Rate of Bone Healing

The healing of injured bone is a highly complex process, and its rate is affected by many variables, including diet, environment, and pathologic condition of the individual. The present study was undertaken in order to develop a radiographic method for determining the healing rate of injured bone. The radiographic approach seemed desirable since it would permit following bone repair in the same animal on a day-by-day basis. Our initial attempts to measure the healing rate of fractured femurs of rats were unsuccessful because of uncontrolled displacement of the bone fragments. In addition, bone splints were destroyed by the animals in spite of all practical precautions. Success was greater when the tibia was substituted for the femur because the fibula served as a natural splint. A method was selected, however, which had been described by Haggar, Kinney, and Kaufman (1), who produced uniform lesions in comparative studies of bone healing in stained sections. In their method a longitudinal cut was made thro...

New Design of a Linearizing Recording Densitometer

In the design and construction of a recording densitometer intended primarily for the evaluation of bone density, a potentiometric system has been substituted for the electromechanical function transformer. In the application of this technique, a wedge is used as a standard object of reference, with the wedge exposed to x rays simultaneously with the exposure of the bone. The present type of wedge has a continuous and constant slope and is made of an aluminum alloy with x ray absorption characteristics similar to those of bone. The pattern wedge obtained on the film reflects film exposure and development conditions. Its densitometrlc curve provides the necessary data needed for correcting the bone scan for integration purposes. M.D.M.)

Determination of small amounts of mineral in bone, cartilage and muscle by x-ray absorption☆

Abstract An earlier method for determining the inorganic content of macro amounts of dried, ground bone has been refined so that specimens as small as 50 mg. can be analyzed with a probable error of less than 2%. Instead of the dry sample used in the earlier study, the inorganic fraction of bone, hyaline cartilage, or striated muscle is placed into solution and the absorbance of K-capture x-radiation from an iron-55 source by 0.04 ml. of the solution is a function of its mineral concentration. It was determined that the effects of sample evaporation and variations of solution temperature upon repeated measurements fall well within 0.5%; but the nonuniformity of sample volumes might cause errors of 1.2% or more.