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Biomedical subjects

A Makepeace

Publications and source records attributed to A Makepeace.

7 recordsLinked to original sources
PubMed1990

X-ray studies of synthetic radiation-counting diamonds.

Synthetic diamonds with a nitrogen content less than 100 ppm may be used as radiation dosemeters in a conduction counting mode, and are especially useful in medical applications. Crystal imperfections, revealed by x-ray diffraction topography, were found to affect counting performance. The best quality diamond gave the highest photocurrent (500 nA at 50 V mm-1 and 2.75 Gy min-1). Diamonds containing dislocations had lower photocurrents but had the advantage of shorter settling times (seconds rather than minutes). Placing contacts on two opposite cube (100) faces gave a higher photocurrent than on a pair of octahedral (111) faces. Higher photocurrents were also achieved when the majority of dislocations were perpendicular rather than parallel, to the electric field. Some recommendations for selecting synthetic diamonds for dosemeters are given.

Carbon↗
PubMed1990

Who gets radiotherapy?

This study investigated the use of radiotherapy for patients perceived to be unsuitable for curative therapy. Patients were grouped according to whether their cancer was considered curable or incurable and whether they received radical or palliative schedules of radiotherapy. The latter group was further evaluated to clarify current practice, to examine the problems in establishing guidelines for treatment and as a basis for prospective audit. Results confirmed that therapy guidelines within the unit were in line with national practice. Changes in standard therapy were proposed in view of resource limitations and recent results from other surveys. A second audit in 1989, together with a formal costing exercise, showed a reduction in the median number of fractions per course in both patient groups. This study suggests that palliative radiotherapy was used selectively for patients likely to receive significant benefit, and that consensus management was practised, and influenced, by informal internal audit. Results highlighted decision-making problems in the management of advanced non-metastasised cancer; confirmed doubts about the advisability of establishing rigid guidelines in palliative therapy; and clarified some of the difficulties in conducting meaningful cost-benefit analyses in this area.

Cancer Care Facilities↗
PubMed1987

Osteosarcoma and other neoplasms of bone. Magnetic resonance spectroscopy to monitor therapy.

Fourteen patients with malignant tumors of bone (ten osteogenic sarcomas, one Ewing's tumor, one giant-cell tumor, two non-Hodgkin's lymphomas), plus one patient with a synovial cell sarcoma, who had been treated by standard extremity-conserving chemotherapy regimens, were examined before treatment by means of localized phosphorus 31 magnetic resonance spectroscopy. Thirteen (86%) of 15 examinations were successful, and 100% of successful examinations showed metabolic abnormality in the tumor. Tumors contained excess adenosine triphosphate and inorganic phosphate, an unusual peak of phosphomonoester, consistent with excessive glycolysis in tumors. The intratumor pH was normal in the 12 bone tumors, but acidic in the single soft-tissue sarcoma (pH 6.8). Metabolic response was observed in all seven patients monitored during chemotherapy, with the earliest examinations being performed two days after first treatment. An increase in the inorganic phosphate level, loss of adenosine triphosphate, and loss of phosphomonoester indicated tumor response; loss of all abnormal metabolites (two of seven patients) indicated regression of the tumor. Tumor relapse was accompanied by reappearance of abnormalities in the magnetic resonance spectrum. Phosphorus 31 magnetic resonance spectroscopy offers a unique means of determining the early response of these malignant tumors to therapy as well as predicting their relapse.

Adenosine Triphosphate↗
PubMedDate not supplied

Use of phosphorus-31 MR spectroscopy to monitor response to chemotherapy in non-Hodgkin lymphoma.

Two patients with non-Hodgkin lymphoma of the femur were examined with 31P magnetic resonance spectroscopy (MRS) and proton magnetic resonance imaging before and during treatment with chemotherapy. Prior to treatment, 31P MRS of the tumor showed that in comparison to normal skeletal muscle, phosphocreatine was reduced, and phosphomonoesters (PME) and phosphodiesters were elevated. The 31P spectrum became similar to that of normal muscle after 40 days of treatment in both cases. Following the initial dose of chemotherapy, an increase in PME relative to adenosine triphosphate was observed within 48 h in one patient. Magnetic resonance showed a change in the soft tissue component of both tumors and 6-12 months later there was no clinical evidence of any recurrence. Magnetic resonance spectroscopy with 31P may prove to be a sensitive technique for monitoring therapeutic response of tumors.

Adult↗
PubMedDate not supplied

Reality bites.

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Clinical Competence↗