Exploring the experiences of UK-based private physiotherapists when running and progressing a physiotherapy business: a hermeneutic phenomenological study.

AIM: To explore the experiences of UK-based private physiotherapists when running and progressing a physiotherapy business. DESIGN: A hermeneutic phenomenological approach. PARTICIPANTS: Six UK-based private physiotherapy practice owners were recruited via purposive and snowball sampling. METHODS: In-depth, semi-structured video interviews (2 per participant), audio-recorded and transcribed. Field notes, respondent validation and a reflexive diary were used. Data underwent line-by-line analysis, identifying codes and themes. Constant comparison of data, codes and themes occurred throughout. Peer review was utilised, small sections of data and all emerging codes were independently reviewed. RESULTS: Three interconnecting themes. Working for myself: participants highlighted the freedom, flexibility and independence of business ownership, whilst acknowledging the additional pressures/challenges associated with this. Evolution of a practice: business growth was slow, requiring income supplementation initially. Successful growth often utilised luck and unexpected opportunities. Working with others: participants faced decisions regarding solo or joint ownership, when/what additional staff were required, whether staff should be employed or self-employed, and how to appropriately manage/support staff. CONCLUSIONS: Private practice ownership brings an array of benefits and challenges. Areas for future research include exploring the stresses of private roles and business ownership, the evolution of private physiotherapy practices, small-scale business partnerships, and employment vs self-employment. CONTRIBUTION OF THE PAPER.

An algorithm for constructing local regions in a phylogenetic network.

The groupings of taxa in a phylogenetic tree cannot represent all the conflicting signals that usually occur among site patterns in aligned homologous genetic sequences. Hence a tree-building program must compromise by reporting a subset of the patterns, using some discriminatory criterion. Thus, in the worst case, out of possibly a large number of equally good trees, only an arbitrarily chosen tree might be reported by the tree-building program as "The Tree." This tree might then be used as a basis for phylogenetic conclusions. One strategy to represent conflicting patterns in the data is to construct a network. The Buneman graph is a theoretically very attractive example of such a network. In particular, a characterization for when this network will be a tree is known. Also the Buneman graph contains each of the most parsimonious trees indicated by the data. In this paper we describe a new method for constructing the Buneman graph that can be used for a generalization of Hadamard conjugation to networks. This new method differs from previous methods by allowing us to focus on local regions of the graph without having to first construct the full graph. The construction is illustrated by an example.

The AAPM/RSNA physics tutorial for residents: internal radiation dosimetry: principles and applications.

Internal dose calculations in nuclear medicine normally use the techniques, equations, and resources provided by the Medical Internal Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine. The MIRD schema uses a unique set of symbols and quantities to calculate the absorbed dose of radiation in any target organ per radioactive decay in any source organ. The calculations involve the energy emitted per radioactive decay, the fraction of the emitted energy that is absorbed in various target organs, the masses of these organs, and both the physical decay and biologic clearance of the injected radioactive material. Standardized mathematical models (phantoms) of the human body and standardized biokinetic models are also used. A computer program, MIRDose, calculates dose tables per unit administered activity of various radiopharmaceuticals. Special care must be taken when nuclear medicine procedures involve pregnant or lactating patients. New methodologies are becoming available to calculate doses to individual patients.

The MIRD perspective 1999. Medical Internal Radiation Dose Committee.

The MIRD schema is a general approach for medical internal radiation dosimetry. Although the schema has traditionally been used for organ dosimetry, it is also applicable to dosimetry at the suborgan, voxel, multicellular and cellular levels. The MIRD pamphlets that follow in this issue and in coming issues, as well as the recent monograph on cellular dosimetry, demonstrate the flexibility of this approach. Furthermore, these pamphlets provide new tools for radionuclide dosimetry applications, including the dynamic bladder model, S values for small structures within the brain (i.e., suborgan dosimetry), voxel S values for constructing three-dimensional dose distributions and dose-volume histograms and techniques for acquiring quantitative distribution and pharmacokinetic data.

MIRD pamphlet No. 17: the dosimetry of nonuniform activity distributions--radionuclide S values at the voxel level. Medical Internal Radiation Dose Committee.

The availability of quantitative three-dimensional in vivo data on radionuclide distributions within the body makes it possible to calculate the corresponding nonuniform distribution of radiation absorbed dose in body organs and tissues. This pamphlet emphasizes the utility of the MIRD schema for such calculations through the use of radionuclide S values defined at the voxel level. The use of both dose point-kernels and Monte Carlo simulation methods is also discussed. PET and SPECT imaging can provide quantitative activity data in voxels of several millimeters on edge. For smaller voxel sizes, accurate data cannot be obtained using present imaging technology. For submillimeter dimensions, autoradiographic methods may be used when tissues are obtained through biopsy or autopsy. Sample S value tabulations for five radionuclides within cubical voxels of 3 mm and 6 mm on edge are given in the appendices to this pamphlet. These S values may be used to construct three-dimensional dose profiles for nonuniform distributions of radioactivity encountered in therapeutic and diagnostic nuclear medicine. Data are also tabulated for 131I in 0.1-mm voxels for use in autoradiography. Two examples illustrating the use of voxel S values are given, followed by a discussion of the use of three-dimensional dose distributions in understanding and predicting biologic response.

Stability of meperidine in an implantable infusion pump using capillary gas chromatography-mass spectrometry and a deuterated internal standard.

A capillary gas chromatographic-mass spectrometric (GC MS) method is described for the analysis of meperidine using 3,3,5,5-[2H4]-meperidine as an internal standard. Chromatography was performed on a (5% phenyl) methylpolysiloxane column (30 m x 0.32 mm I.D., 0.25 microm film thickness) operated at 195 degrees C; helium carrier gas-50 cm/s(-1), tR = 2.3 min. Ionization was by electron impact (EI) and detection by selected ion monitoring of the molecular ions. The method provided high response linearity (mean r = 0.9982) and precision (< 6.5% C.V.). Application of this method to a pilot study of aqueous meperidine x HCl (10 mg/ml(-1)) stability in a surgically implantable infusion pump at 37 degrees C for 90 days revealed no demonstrable drug degradation.

A history of medical internal dosimetry.

This paper presents a short history of the development of medical internal dosimetry. It reviews the evolution of the equations and discusses the development of various mathematical models used to improve radiation absorbed dose estimates. The contributions of Leonidas Marinelli, Edith Quimby, William Mayneord, Robert Loevinger, Walter Snyder, and others are emphasized.

MIRD formulation.

The MIRD scheme is not restricted to calculating mean absorbed doses in organs but can be extended to any tissue for which distribution and retention data can be obtained and for which a reasonably accurate mathematical description of the source and target tissues can be determined. The development of more accurate absorbed dose estimates and the correlation of these estimates with radiation effects will lead to a better understanding of the results from radiotherapeutic agents such as radiolabeled monoclonal antibodies. Therefore, radiobiologists and internal dosimetrists need to combine their efforts and work toward the common goal of improving the treatment of malignant diseases.

Radiation dosimetry for the adult female and fetus from iodine-131 administration in hyperthyroidism.

Through a study of the iodine kinetics of 127 patients, we have developed radiation dose estimates to major organs and the fetus for patients with varying degrees of hyperthyroidism. We observed a negative correlation between maximum thyroid uptake and biologic half-time of iodine in the thyroid and used this correlation to predict the biologic half-time at fixed values of maximum thyroid uptake. Dose estimates to the bladder, gonads, marrow, thyroid, uterus, and whole body were estimated for maximum thyroid uptakes from 20% to 100%. Bladder dose varied from 0.6 to 1.0 mGy/MBq and dose to the uterus varied from 0.036 to 0.063 mGy/MBq under different model assumptions. Dose estimates to the fetus and fetal thyroid were approximated at all stages of pregnancy. Average fetal dose was a maximum between 0 and 2 mo of pregnancy, with the maximum ranging from 0.048 mGy/MBq to 0.083 mGy/MBq, depending on model assumptions. Some radiation risks for irradiation of the fetus and the fetal thyroid are discussed.

A model of the peritoneal cavity for use in internal dosimetry.

Several therapeutic and diagnostic techniques involve injection of radioactive material into the peritoneal cavity. Estimation of the radiation dose to the surface of the peritoneum or to surrounding organs is hampered by the lack of a suitable source region in the phantom commonly used for such calculations. We have modified the Fisher-Snyder phantom to include a region representing the peritoneal cavity which may be employed to estimate such radiation doses. A geometric model is described which is coordinated with the existing organ regions in the phantom. Specific absorbed fractions (derived by Monte Carlo techniques) for photon emissions originating within the cavity are listed. Photon S-values for several radionuclides which have been administered intraperitoneally are shown. Dose conversion factors for electrons irradiating the peritoneal cavity wall, from either a thin plane or volume source of activity within the cavity, are also given for several nuclides.

Dosimetry of leukocytes labeled with 99Tcm-albumin colloid.

Biodistribution, kinetics and dosimetry of 9Tcm-albumin colloid labeled leukocytes (TAC-WBC) is described. A practical method of planar image data acquisition and processing is discussed. This method was used to obtain biodistribution data in 11 patients, two of whom were children. Dosimetry was calculated for fetuses, children and adults. The spleen is the critical organ, receiving 2.5 rad per 5 mCi procedure in adults and 3.6 rad per 2.15 mCi procedure in a 5-year-old child. These absorbed doses are about one-sixth of that absorbed from 111In-leukocytes procedures utilizing one-tenth the administered activity of TAC-WBC. The liver and red marrow are approximately equivalent secondary target organs, each receiving about 20% of the spleen dose. Fetal doses at any stage of gestation are similar, averaging about 14 mrad per mCi of TAC-WBC administered to the mother. The dosimetry of TAC-WBC is favorable enough to permit its use in children, adults and during pregnancy.

Hematologic depression following therapy with strontium-89 chloride.

Initial clinical trials using strontium-89 (Sr-89) chloride for the treatment of painful skeletal metastases have observed minimal or no hematological depression secondary to the radiostrontium. A patient with marked bone marrow depression temporally related to the administration of the Sr-89 is reported, and the need for close hematological monitoring is emphasized. Bone marrow tumor replacement may predispose patients to marrow depression from radiostrontium, and such patients should be treated with caution.

A new osmium-191/iridium-191m radionuclide generator system using activated carbon.

A new osmium-191/iridium-191m (191Os/191mIr) radionuclide generator system has been developed based on the absorption of K2OsCl6 (Os-IV) on 140-230 mesh heat-treated activated carbon. The generator is eluted with pH 2 saline solution containing 0.25 g/l Kl to give 191mIr in good yield. The generator eluent is neutralized to physiologic pH and isotonicity with Tris buffer immediately prior to i.v. injection. No scavenger column is required. As an example, elution of the prototype generator with a 2-ml bolus results in elution of 191mIr in approximately 18% yield with an 191Os breakthrough of only 2 X 10(-4)%/bolus. The prototype generator has consistent performance over a 2-wk period with no change in 191mIr yield or 191Os breakthrough. Loading of up to 1.5 Ci of 191Os results in no observed radiolysis. Continuous elution of this system is also possible with a mean 191mIr yield of 3.7%/ml and a mean 191Os breakthrough of 2 X 10(-5)%/ml at a flow rate of 12 ml/min. This new system represents a readily available source of 191mIr for radioangiography. Adsorbed radiation dose calculations indicate a total-body dose of only 3.9 mrad for a 100 mCi injected bolus.

Contribution of contaminant indium-114m/indium-114 to indium-111 oxine blood dosimetry.

Indium-114m and 114In appear as contaminants in commercial preparations of [111In]oxine at a level of about 0.05% at time of calibration (TOC). The contribution of these contaminants to the radiation absorbed dose from [111In]oxine leukocyte, platelet, and erythrocyte imaging procedures has been evaluated. When the absorbed dose from these contaminants is expressed as a percent of the 111In dose to the same organ from a given procedure, the contaminants contribute an additional 0.16 to 12% of the 111In dose, and in one case, that of the spleen from [111In]oxine labeled erythrocytes, they contribute an additional 33%. Commercial samples of aqueous-based [111In]oxine contain levels of 114mIn/114In sufficient to result in a mild to moderate increase in the absorbed radiation dose to the patient. Strict quality control procedures must be maintained by suppliers to prevent higher contamination levels. It is advisable to avoid using 111In products of this nature later than about 3 days after the time of calibration.