Impact of dose hot spots on spinal cord tolerance following stereotactic body radiotherapy: a generalized biological effective dose analysis

The purpose of this study was to investigate the effects of high-dose inhomogeneous irradiation to small volumes of spinal cord with a new generalized biological effective dose (gBED) analysis for spine stereotactic body radiotherapy (SBRT). The gBED was applied to spinal cord dosimetric data (contoured per the thecal sac) at specified volumes for a cohort of five patients with radiation-induced myelopathy (RM) and compared to nineteen patients without RM post-SBRT. The spinal cord gBED was calculated and normalized to a conventional 2-Gy equivalent dose fraction scheme (α/β = 2 Gy for late toxicity). Differences between the conventional BED and those gBED calculations by accounting for small-volume dosing within the spinal cord was observed. Statistically significant differences in the mean gBED between the RM group and the non-RM group was observed both at the maximum point volume (gBED of 66 Gy vs. 37 Gy (p = 0.01), respectively) and at the 0.1 cm(3) volume (gBED of 53 Gy vs. 28 Gy (p = 0.01), respectively). No significant difference at the 0.1 cm(3) volume was observed based on the mean BED comparisons. No significant differences were observed at the larger 1 cm(3), 2 cm(3) or 5 cm(3) volumes for either BED or gBED comparisons. We conclude that differences in dose hot spots characteristics within small inhomogenously irradiated volumes of spinal cord can affect spinal cord tolerance following SBRT treatments.

Image-guided radiosurgery in the treatment of spinal metastases

Object

The authors describe a new method for treating metastatic spinal tumors in which noninvasive, image-guided, frameless stereotactic radiosurgery is performed. Stereotactic radiosurgery delivers a high dose of radiation in a single or limited number of fractions to a lesion while maintaining delivery of a low dose to adjacent normal structures.

Methods

Image-guided radiosurgery was developed by coupling an orthogonal pair of real-time x-ray cameras to a dynamically manipulated robot-mounted linear accelerator that guides the radiation beam to treatment sites associated with radiographic landmarks. This procedure can be conducted in an outpatient setting without the use of frame-based skeletal fixation. The system relies on skeletal landmarks or implanted fiducial markers to locate treatment targets. Four patients with spinal metastases underwent radiosurgery with total prescription doses of 1000 to 1600 cGy in one or two fractions. Alignment of the treatment dose with the target volume was accurate to within 1.5 mm. During the course of each treatment fraction, patient movement was less than 0.5 mm on average. Dosimetry was highly conformal, with a demonstrated ability to deliver 1600 cGy to the perimeter of an irregular target volume while keeping exposure to the cord itself below 800 cGy.

Conclusions

These experiences indicate that frameless radiosurgery is a viable therapeutic option for metastatic spine disease.

Radiation induces upregulation of cyclooxygenase-2 (COX-2) protein in PC-3 cells

PURPOSE

To investigate the impact of gamma-irradiation on cyclooxygenase-2 (COX-2) expression and its enzymatic activity in PC-3 cells. Cell cycle redistribution, viability, and apoptosis were quantitated in control and irradiated cells with or without the COX-2 inhibitor NS-398.

METHODS AND MATERIALS

Western blot analysis was used to assess COX-2 protein expression. Prostaglandin (PGE(2)) was measured after addition of arachidonic acid (AA) using a Monoclonal Immunoassay Kit. Cell cycle and apoptosis were assessed using flow cytometry.

RESULTS

We observed a dose-dependent increase in COX-2 of 37.0%, 79.7%, and 97.5% following irradiation with 5, 10, and 15 Gy, respectively. The PGE(2) level of irradiated cells was higher than in controls (1512 +/- 157.5 vs. 973.7 +/- 54.2 rhog PGE(2)/mL; p < 0.005, n = 4) while cells irradiated in the presence of NS-398 had reduced PGE(2) levels (218.8 +/- 80.1 rhog PGE(2)/mL; p < 0.005; n = 4). We found no differences in cell cycle distribution or apoptosis between cells irradiated in the presence or absence of NS-398.

CONCLUSIONS

COX-2 protein is upregulated and enzymatically active after irradiation, resulting in elevated levels of PGE(2). This effect can be suppressed by NS-398, which has clinical implications for therapies combining COX-2 inhibitors with radiation therapy.

Private and local authority children's homes: a comparison

This paper compares residents and staff in 48 English local authority children' homes with those in eight private ones. On average, residents in private homes were further away from their family, more "difficult", more likely to be placed for "treatment", in less close touch with their families and less clear about and satisfied with their care plans. They were also more committed to their residential homes, less likely to be bullied and under less pressure to take drugs. Staff, particularly more experienced staff, in private homes had higher morale. The paper discusses the reasons for these differences and their implications.

Treatment of cutaneous T-cell lymphoma with chimeric anti-CD4 monoclonal antibody

Chimeric anti-CD4 monoclonal antibody was administered intravenously as a single dose to eight patients with mycosis fungoides. The dose was escalated throughout the study between patients groups, and individual patients received 50, 100, or 200 mg per dose. Seven of eight patients responded to treatment with an average freedom from progression of 25 weeks (range, 6 to 52 weeks). The treatment was well tolerated, and there was no clinical evidence of immunosuppression. Following treatment, there was significant suppression of peripheral blood CD4 counts in all patients for 1 to 22+ weeks. Only one patient made a very low titer human antichimeric antibody response. All but two patients made primary antibody and T-cell proliferative responses to a foreign antigen administered 24 hours after antibody infusion. However, there was generally marked, but temporary suppression of T-cell proliferative responses in vitro to phytohemagglutinin (PHA), tetanus toxoid, and normal donor lymphocytes. We conclude that at the dose levels studied, this antibody (1) had clinical efficacy against mycosis fungoides; (2) was well tolerated; (3) had a low level of immunogenicity; (4) decreased T-cell proliferative responses in vitro, and (5) did not induce tolerance to a foreign antigen.

Skill mix in nursing: a selective review of the literature

The issues surrounding skill mix are often highly contentious and, not surprisingly, various interest groups either welcome or reject attempts to examine the different combinations of staff, qualified and unqualified, experienced and inexperienced, in relation to costs, outcomes and quality of nursing care. Despite the strong passions aroused by the debate, other factors, most notably demographic changes and the possible shortage of nurses, new demands on health care services and the call for more cost-effective use of resources, have kept skill mix foremost on the policy agenda. The review covers manpower planning, an area where considerable efforts have been made to determine the number but rarely the mix of nurses required to provide the necessary care for patients. In addition, previous work on staff turnover, and the possibility of substituting less qualified for more qualified staff, are examined in relation to cost-containment, recruitment and demography, and the creation of a new single level of nurse. These factors, along with the introduction of health care assistants, will have an important influence on the future shape and structure of nursing and, of course, the composition of the skills available. While calling for further work on skill mix, the review provides a timely reminder that the issues are complex and often highly political.

Higher education: the coping stone of nursing education?

For many years the nursing profession in the United Kingdom has sought ways of improving the education of nurses. The present article explores some of the issues surrounding the recent proposals for an alternative to the long-standing apprenticeship system, namely that of moving basic nurse education into institutions of higher education. In particular, it focuses upon and explores the views of clinical nurse teachers and nurse tutors. In order to provide an historical context, the article begins by outlining the history of nurse education over the last century with reference to the various reports that have been published throughout the period. Before discussing the results of a questionnaire completed by those currently involved in the training and education of nurses, the article also considers the experience of other countries where collegiate education for nurses has been introduced.