Radiosurgery planning supported by the GEMSS grid

GEMSS (Grid Enabled Medical Simulation Services IST-2001-37153) is an EU project funded to provide a test bed for Grid-enabled health applications. Its purpose is evaluation of Grid computing in the health sector. The health context imposes particular constraints on Grid infrastructure design, and it is this that has driven the feature set of the middleware. In addition to security, the time critical nature of health applications is accommodated by a Quality of Service component, and support for a well defined business model is also included. This paper documents experience of a GEMSS compliant radiosurgery application running within the Medical Physics department at the Royal Hallamshire Hospital in the UK. An outline of the Grid-enabled RAPT radiosurgery application is presented and preliminary experience of its use in the hospital environment is reported. The performance of the software is compared against GammaPlan (an industry standard) and advantages/disadvantages are highlighted. The RAPT software relies on features of the GEMSS middleware that are integral to the success of this application, and together they provide a glimpse of an enabling technology that can impact upon patient management in the 21st century.

Gamma knife radiosurgery for cerebral arteriovenous malformations

Since its introduction, gamma knife radiosurgery has become an important treatment modality for cerebral arteriovenous malformations. This paper is a brief overview of the technique used, of the clinical results achieved and of the experience gained in Sheffield.

Gamma knife stereotactic radiosurgery for unilateral acoustic neuromas

OBJECTIVE

To evaluate the clinical results achievable using current techniques of gamma knife stereotactic radiosurgery to treat sporadic unilateral acoustic neuromas.

METHODS

A retrospective review of 234 consecutive patients treated for unilateral acoustic neuromas between 1996 and 1999, with a mean (SD) follow up of 35 (16) months. Tumour control was assessed with serial radiological imaging and by the need for surgical intervention. Hearing preservation was assessed using Gardner-Robertson grades. Details of complications including cranial neuropathies and non-specific vestibulo-cochlear symptoms are included.

RESULTS

A tumour control rate in excess of 92% was achieved, with only 3% of patients undergoing surgery after radiosurgery. Results were less good for larger tumours, but control rates of 75% were achieved for 35-45 mm diameter lesions. Of patients with discernible hearing, Gardner-Robertson grades were unchanged in 75%. Facial nerve function was adversely affected in 4.5%, but fewer than 1% of patients had persistent weakness. Trigeminal symptoms improved in 3%, but developed in 5% of patients, being persistent in less than 1.5%. Transient non-specific vestibulo-cochlear symptoms were reported by 13% of patients.

CONCLUSIONS

Tumour control rates, while difficult to define, are comparable after radiosurgery with those experienced after surgery. The complications and morbidity after radiosurgery are far less frequent than those encountered after surgery. This, combined with its minimally invasive nature, may make radiosurgery increasingly the treatment of choice for small and medium sized acoustic neuromas.

Clinical experience with gamma knife stereotactic radiosurgery in the management of vestibular schwannomas secondary to type 2 neurofibromatosis

OBJECTIVE

To evaluate the results of stereotactic radiosurgery treating vestibular schwannomas secondary to type 2 neurofibromatosis.

METHODS

A retrospective review of 122 type 2 neurofibromatosis vestibular schwannomas consecutively treated in 96 patients. Tumour control was assessed by recourse to surgical intervention, by serial radiological imaging, and by the calculation of relative growth ratios in patients (n=29) habouring untreated contralateral tumours to act as internal controls. Hearing function was assessed with Gardner-Robertson grades and with averaged pure tone audiogram thresholds. Other complications are detailed.

RESULTS

Applying current techniques, eight years after radiosurgery it was estimated that 20% of patients will have undergone surgery for their tumour, 50% will have radiologically controlled tumours, and in 30% there will be some variable concern about tumour control, but up to that time they will have been managed conservatively. Relative growth ratios one and two years after treatment indicate that radiosurgery confers a significant (p=0.01) advantage over the natural history of the disease. Analysis of these ratios beyond two years was precluded by the need to intervene and radiosurgically treat the contralateral control tumours in more than 50% of the cases. This growth control was achieved with 40% of patients retaining their Gardner-Robertson hearing grades three years after treatment, (40% having some deterioration in grade, 20% becoming deaf). Pure tone audiogram results suggest some progressive long term hearing loss, although interpretation of this is difficult. Facial and trigeminal neuropathy occurred in 5% and 2%.

CONCLUSIONS

Radiosurgery is a valuable minimally invasive alternative treatment for these tumours. For most patients, it controls growth or defers the need for surgery, or both. There is a price in terms of hearing function, although this may compare favourably with the deafness associated with the natural history of the disease, and with surgery. In deciding on therapy, patients should be aware of this treatment option.

Changing utilization of stereotactic radiosurgery in the UK: the Sheffield experience

Recognizing a change in our workload and variabilities in referral patterns, we reviewed our previous activity from 1994 to 2000 retrospectively and examined prospectively formal referrals to the Unit in 2001. Arteriovenous malformations still constitute 30% of referrals and treatments, although as a proportion of our workload, this has declined. Radiosurgery is increasingly being chosen as a first line treatment for small and moderate-sized acoustic neuromas, although referral rates vary widely, some neuroscience units referring all and others none of their acoustic neuromas at least for a radiosurgical opinion. About 100 meningiomas, mainly skull-base and/or recurrent tumours after previous surgery, are now treated per year. Compared with other units world-wide, very few pituitary adenomas and cerebral metastases are treated. The implications of this are discussed.

Malignancy in a vestibular schwannoma. Report of a case with central neurofibromatosis, treated by both stereotactic radiosurgery and surgical excision, with a review of the literature

Malignant change in schwannoma is rare. Malignant change in a vestibular schwannoma (acoustic neuroma) is even more rare. This paper presents a case of rapidly growing vestibular schwannoma first treated by radiosurgery whose histopathology after surgical excision 42 months later showed malignant changes. Up to now, eight cases of malignancy in eighth nerve tumours have been reported, four of which, including the present case, had previously been treated with radiosurgery and four cases that had not received radiation. Thus, it would seem, the overall incidence is extremely low. Nevertheless, extreme vigilance and careful reporting continues to be necessary.

No more tours: how library tours of the past become today's celebrations

In 1999, Northwestern University's Galter Health Sciences Library redesigned the library orientation program for first-year medical students. Surveys indicated tours were ineffective and students retained little of the information presented. Furthermore, the tour was not related to the student's curriculum and did not reinforce their learning objectives. As a replacement, the library staff developed a self-directed two-hour library open house. Stations throughout the library showcased the library staff, services, and resources, focusing on the first-year student curriculum. A follow-up survey found this redesign more useful and relevant to the students' course work, indicating libraries should be creating more interactive tours for students allowing them to learn actively.

Cerebral arteriovenous malformations: comparison of novel magnetic resonance angiographic techniques and conventional catheter angiography

OBJECTIVE

To investigate the potential of novel magnetic resonance (MR) angiographic techniques for the assessment of cerebral arteriovenous malformations.

METHODS

Forty patients who were about to undergo stereotactic radiosurgery were prospectively recruited. Three-dimensional, sliding-slab interleaved ky (SLINKY), time-of-flight acquisition was performed, as was a dynamic MR digital subtraction angiography (DSA) procedure in which single thick slices (6-10 cm) were obtained using a radiofrequency spoiled Fourier-acquired steady-state sequence (1 image/s). Sixty images were acquired, in two or three projections, during passage of a 6- to 10-ml bolus of gadolinium chelate. Subtraction and postprocessing were performed, and images were viewed in an inverted cine mode. SLINKY time-of-flight acquisition was repeated after the administration of gadolinium. Routine stereotactic conventional catheter angiography was performed after MR imaging. All images were assessed (in a blinded randomized manner) for Spetzler-Martin grading and determination of associated vascular pathological features.

RESULTS

Forty-one arteriovenous malformations were assessed in 40 patients. Contrast-enhanced (CE) SLINKY MR angiography was the most consistent MR imaging technique, yielding a 95% correlation with the Spetzler-Martin classification defined by conventional catheter angiography; MR DSA exhibited 90% agreement, and SLINKY MR angiography exhibited 81% agreement. CE SLINKY MR angiography provided improved nidus delineation, compared with non-CE SLINKY MR angiography. Dynamic information from MR DSA significantly improved the observation of early-draining veins and associated aneurysms.

CONCLUSION

CE SLINKY MR angiographic assessment of cerebral arteriovenous malformations offers significant advantages, compared with the use of non-CE SLINKY MR angiography, including improved nidus demonstration. MR DSA shows promise as a noninvasive method for dynamic angiography but is presently restricted by limitations in both temporal and spatial resolution.

Reporting the Potential Benefits of New Technologies for Cervical Cancer Screening

The AHCPR released its evidence-based report, "Evaluation of Cervical Cytology" in early 1999. This report represents the most comprehensive analysis available to date of Pap smears and new technologies designed to improve cervical cancer screening. Both the ACOG and the AHCPR have released simplified summaries of the results of the evidence report that may lead to misunderstandings of the potential clinical impact of these new technologies. This report reviews the 4 major statements in these summaries and discusses how they are either incorrect based on the full AHCPR report or may be misinterpreted because their ramifications are not fully discussed. New screening technology has the potential to finally bring the sensitivity of a new Pap test to an acceptable level. The increased sensitivity afforded by these new technologies can reduce negative outcomes at reasonable cost-effectiveness ratios and at an equivalent or superior specificity compared to the conventional Pap smear.

An improved technique for comparing Gamma Knife dose-volume distributions in stereotactic radiosurgery

A function derived from the geometry of brachytherapy dose distributions is applied to stereotactic radiosurgery and an algorithm for the production of a novel dose-volume histogram, the Anderson inverse-square shifted dose-volume histogram (DVH), is proposed. The expected form of the function to be plotted is checked by calculating its value for single focus exposures, and its application to clinical examples of Gamma Knife treatments described. The technique is shown to provide a valuable tool for assessing the adequacy of radiosurgical plans and comparing and reporting dose distributions.

Randomized double-blind trial of beta-carotene and vitamin C in women with minor cervical abnormalities

A double-blind, placebo-controlled, randomized, factorial study using a daily oral administration of 30 mg beta-carotene and/or 500 mg vitamin C was conducted in 141 women with colposcopically and histologically confirmed minor squamous atypia or cervical intra-epithelial neoplasia (CIN) I. Over approximately 2 years of follow-up, 43 lesions regressed to normal and 13 progressed to CIN II. The regression rate was slightly higher, but not significantly so, in those randomized to beta-carotene compared to no beta-carotene (hazard ratio = 1.58, 95% CI: 0.86-2.93, P = 0.14) and slightly lower, but not statistically significant, for those randomized to vitamin C compared to no vitamin C (hazard ratio = 0.65, 95% CI: 0.35-1.21, P = 0.17). In a model with no interaction, the progression rate was slightly higher in those randomized to beta-carotene (hazard ratio = 1.75, 95% CI: 0.57-5.36, P = 0.32) and also in those randomized to vitamin C (hazard ratio = 2.40, 95% CI: 0.74-7.80, P = 0.13). Neither of these were statistically significant. However, there was some evidence of an interaction effect of the two compounds on the progression rate (P = 0.052), with seven of the progressed lesions occurring in those randomized to both vitamins compared to a total of six in the three other groups. The currently available evidence from this and other trials suggests that high doses of these compounds are unlikely to increase the regression or decrease the progression of minor atypia and CIN I.

Vulvar intraepithelial neoplasia III: occult cancer and the impact of margin status on recurrence

OBJECTIVE

To determine the impact of margin status on disease recurrence and the incidence of occult cancer in women diagnosed with vulvar intraepithelial neoplasia (VIN) III and treated with surgical excision.

METHODS

Between 1989 and 1995, 73 women were diagnosed preoperatively with VIN III by vulvar biopsy and were treated with surgical resection. Patients were examined postoperatively, and recurrence was diagnosed when a biopsy of suspicious lesions confirmed VIN III.

RESULTS

The mean age was 45 years; 81% of the patients were white, and 18% were black. Eighty-two percent of the women had used tobacco, 56% had prior cervical dysplasia, and 37% had prior genital warts. An underlying squamous vulvar cancer was found in 22% of patients at initial treatment for VIN III. Fifty-nine women had follow-up of at least 7 months. Of these, 66% (39 of 59) had positive surgical margins, 31% (18 of 59) had negative margins and 3% had unknown margins (two of 59). With positive margins, 46% (18 of 39) suffered recurrent disease; with negative margins, only 17% (three of 18) had recurrent disease (P = .03). Multifocal disease and a history of genital warts also correlated with VIN III recurrence (P = .03 for both).

CONCLUSION

A significant number of women diagnosed initially with VIN III on a vulvar biopsy harbored occult vulvar cancer. Recurrences were almost threefold higher when margins were positive for residual VIN III. We conclude that surgical resection is an appropriate method of treatment of VIN III for both diagnostic and therapeutic purposes.

Exploring the nature of the relationship between child sexual abuse and substance use among women

AIMS

This study investigated whether child abuse (CSA) was associated with earlier substance use and greater severity of substance dependence and what aspects of CSA might predict substance abuse.

DESIGN

The study compared (a) drug and alcohol treatment clients with and without a history of CSA and (b) CSA survivors outside drug and alcohol treatment who did or did not have current substance abuse.

SETTINGS

Semi-structured interviews took place at participants' homes, treatment agencies or the research centre.

PARTICIPANTS

Volunteer participants included 100 women recruited from drug and alcohol treatment programmes and 80 CSA survivors recruited through CSA counseling services and medial advertising.

MEASUREMENTS

The results focus on data from the Opiate Treatment Index, Severity of Alcohol Dependence Questionnaire, Substance Dependence Scale, Self-Esteem Inventory and self-reported histories of CSA.

FINDINGS

There were no differences between CSA survivors and other drug and alcohol treatment clients in their severity of dependence. Women with a history of CSA more frequently identified stimulants as their main problem drug and reported an earlier age of first intoxication and earlier use of inhalants. Among abused CSA survivors outside drug and alcohol treatment, women with current substance abuse had typically been abused during adolescence by someone outside the family, whereas those without current substance abuse were typically abused by family members before adolescence.

CONCLUSIONS

The results suggest that adolescence is a crucial time for the influence of CSA experiences on substance abuse.

Metabolic and inflammatory responses after laparoscopic and open inguinal hernia repair

A prospective comparison of metabolic and inflammatory responses after laparoscopic and open inguinal hernia operations was undertaken. There were 10 patients in each group. Plasma levels of cortisol, growth hormone, prolactin, C-reactive protein (CRP) and interleukin-6 (IL-6) were measured preoperatively and at fixed intervals up to 120 h postoperatively. In vitro, endotoxin stimulated whole blood tumour necrosis factor alpha (TNF alpha) was measured in preoperative and 24 h postoperative blood samples. Changes in the plasma levels of cortisol, growth hormone and prolactin showed no statistically significant difference between the groups. No significant change in IL-6 levels were recorded in any group. Changes in CRP levels were significantly higher (P < 0.006) in open hernia patients. Endotoxin stimulated TNF alpha production was suppressed in both groups. The degree of suppression in open hernia patients was significantly higher (P < 0.005). This study has shown that both these operations produce similar stress responses. However, open hernia operation results in a higher acute phase response and induces a greater endotoxin tolerance.

Stereotactic localization with magnetic resonance imaging: a phantom study to compare the accuracy obtained using two-dimensional and three-dimensional data acquisitions

OBJECTIVE

To compare the accuracy of stereotactic localization using magnetic resonance imaging (Siemens 1.5-T Magnetom; Siemens, Erlangen, Germany) with two-dimensional and three-dimensional data acquisition techniques.

METHODS

A phantom study was performed in which the coordinates of an array of rods were determined from images in both two-dimensional and three-dimensional studies and compared with measured values in a series of transverse, coronal, and sagittal images.

RESULTS

The results demonstrated a distinct advantage in using three-dimensional acquisition; an error greater than 2 mm was identified in only 0.8% of the imaged volume, compared with 12% of the imaged volume in the two-dimensional study.

CONCLUSION

The results indicated that more accurate stereotactic localization is achieved with a three-dimensional acquisition.

Prediction of obliteration of arteriovenous malformations after radiosurgery: the obliteration prediction index

OBJECTIVE

To describe the response to single dose photon stereotactic radiosurgery of arteriovenous malformations (AVMs) so that the probability of success or failure of treatment may be predicted for the individual patient.

METHOD

The obliteration prediction index (OPI) was calculated for AVMs by dividing the marginal dose of radiation in Gray (Gy) by the lesion diameter in centimetres in cohorts of 42 patients treated with the modified linear accelerator at Toronto-Sunnybrook Regional Cancer Centre and 394 patients treated with the gamma unit at the Royal Hallamshire Hospital, Sheffield, United Kingdom. Patients were grouped into ranges by OPI and the proportion of success and failure was calculated for each group. An exponential function [P = 1-A.e(-B.OPI)] was fitted to the data by the least squares method.

RESULTS

Despite systematic differences in radiation treatment, that is, marginal doses of 15 and 20 Gy in Toronto and most Sheffield patients with a marginal dose of 25 Gy, the resultant data points exhibited similar behaviour.

CONCLUSION

The function [P = 1-A.e(-B.OPI)] partly describes the biological effect of radiation and is independent of the radiation device used. Radiosurgery centres can use this model to facilitate predictions of successful treatment for individual patients.

The use of single fraction Leksell stereotactic radiosurgery in the treatment of uveal melanoma

Fourteen patients with posterior uveal melanomas were treated using single fraction stereotactic radiosurgery. In each case a dose of 70 Gy was administered to the periphery of the tumour. Regression of the tumour has been observed in 13 patients, whilst the lesion has remained unchanged in one patient. The visual acuity has deteriorated in all 14 patients. Significant radiation induced adverse reactions were noted in 13 patients and include; retinopathy, optic neuropathy, rubeosis iridis, and secondary glaucoma. Two patients have required enucleation because of intractable rubeotic glaucoma. One patient has died from proven metastases. Although stereotactic radiosurgery appears to be a practical and effective method of treating uveal melanomas, its usefulness is limited by a high incidence of radiation induced adverse reactions. Further work is required to refine the current treatment protocol and establish an optimal prescription dose.

Intensive outpatient adjuvant therapy for breast cancer: results of dose escalation and quality of life

PURPOSE

A dose-escalation study was conducted to determine the maximum-tolerated dose (MTD) and dose-limiting toxicities (DLTs) of cyclophosphamide (CY) in combination with granulocyte colony-stimulating factor (G-CSF0 and doxorubicin (DOX) given every 2 weeks for eight cycles as outpatient adjuvant therapy for node-positive breast cancer. A pilot study to assess quality of life (QOL) was performed.

PATIENTS AND METHODS

From March 1991 to April 1993, 19 patients were entered. Patients received escalating doses of CY intravenously (i.v.) (1,000 mg/m2, 1,500 mg/m2, 2,000 mg/m2, or 2,500 mg/m2) with DOX 40 mg/m2, G-CSF 10 micrograms/kg/d on days 2 to 12, and mesna, every 2 weeks for eight cycles. QOL was measured by the Profile of Mood States (POMS), the Psychosocial Adjustment to Illness Scale-Self Report (PAIS-SR), and a 27-item QOL scale.

RESULTS

The CY dose of 2,500 mg/m2 every 2 weeks elicited toxicities that required dose reductions secondary to a combination of thrombocytopenia, hematuria, and anemia that required transfusion. The dose of 2,000 mg/m2 resulted in an acceptable toxicity profile. Ninety-two percent of cycles at the 2,000-mg/m2 dose were delivered on schedule and 77% without hospitalization. QOL assessments indicated high levels of distress measured by POMS in 47%, poor overall quality of life in 40%, and significant problems with physical symptoms in less than 27% of all patients for any given cycle.

CONCLUSION

A dose of CY at 2,000 mg/m2 can be administered every 2 weeks with DOX and G-CSF for eight cycles in the outpatient setting with manageable toxicity. The majority of women described levels of physical symptoms and emotional distress as tolerable during treatment.

Radiosurgery: a minimally interventional alternative to microsurgery in the management of acoustic neuroma

We report the results of treatment with radiosurgery of 29 tumours in 27 patients with acoustic neuromas between 1986 and 1989. The median follow-up was 6.6 years. The treatment appears to be an effective alternative to surgery for patients with tumours of 3 cm diameter or less. The mortality and morbidity of the treatment and the presentation of cranial nerve function is comparable to the very best surgical results. Every patient with an acoustic neuroma should be informed about this alternative to direct surgery.

Differences in serum luteinizing hormone measurements by immunoradiometric assay induced by kinetic manipulation of assay conditions are dependent on the endocrine milieu of serum

Divergent estimates for luteinizing hormone (LH) in individual serum samples may be given by different immunoassays. In order to investigate this phenomenom further, we have studied the effect of differences in assay kinetics within the same immunoradiometric assay (IRMA) configuration on LH measurement in sera from different endocrine states. Three pairs of monoclonal/polyclonal two-site IRMA systems for LH were developed from three LH monoclonal antibodies and a common polyclonal anti-human chorionic gonadotrophin. For IRMA systems a short and long assay, which were different only with respect to the incubation time (1/2 h and overnight respectively), of the labelled monoclonal first antibody were performed. The IRMAs were all standardized against the LH international reference preparation 68/40. LH concentrations were measured by all the IRMAs in sera obtained from normal men (n = 11) and from women with polycystic ovarian syndrome (PCO; n = 13). In normal men, there were no differences in LH estimates between the short and the long assays of the three IRMA systems, and the ratios of long to short assays were similar for all the systems. However, in PCO there were significant differences between short and long assays and the ratios of long to short assays were different for the IRMA systems. These results indicate that kinetic differences between IRMAs of the same antibody configuration can be associated with differences in measured LH concentrations, depending on the endocrine status of the sera studied. As LH glycoform patterns are known to differ between normal men and PCO, the observed changes in LH estimates may be due to the different glycoform composition.

Accuracy of stereotactic localisation using magnetic resonance imaging: a comparison between two- and three-dimensional studies

The accuracy of stereotactic localisation using magnetic resonance (MR) imaging has been assessed in a phantom study. Parallel studies compared the accuracy obtained. First, a series of two-dimensional (2D) MR slices (transverse, coronal, and sagittal) was acquired sequentially to image the three-dimensional (3D) volume of the phantom. Then, the same volume was imaged in a 3D MR study in which the entire volume was excited simultaneously and 2D slices in transverse, coronal, and sagittal planes were then reconstructed from the 3D data set. The results showed that the 3D acquisition gave superior results in all three planes, and overall it was found that only 1% of the phantom volume was affected by an error greater than 2 mm, compared with 11% for the 2D study. New facilities for image quality assurance provided in GammaPlan version 3.0 have been tested against images from the 2D study with known distortion and consequent localisation errors and successfully identified all images in which the localisation errors were likely to be greater than 3.7 mm.

A phantom study to assess the accuracy of stereotactic localization, using T1-weighted magnetic resonance imaging with the Leksell stereotactic system

This phantom study assesses the accuracy of stereotactic localization using the Leksell G frame (Elekta Instruments AB, Stockholm, Sweden) with T1-weighted magnetic resonance imaging (Siemens 1.5 T Magnetom; Erlangen, Germany). The coordinates of an array of solid perspex rods were determined and compared with measured values in a series of transverse, coronal, and sagittal images. The maximum absolute errors observed (X = 2.7 mm, Y = 7.0 mm, Z = 8.0 mm) were discouraging. However, the more reasonable mean errors (X = 0.4 mm, Y = 0.7 mm, Z = 1.3 mm) reflect considerable variation in accuracy throughout the volume assessed and limitation of maximum errors to specific areas. We present details of the spatial variation and discuss possible mechanisms for improving accuracy. The overall results are of direct relevance only to the scanner used. These results are, however, an indication of the need to approach with caution stereotactic localization using magnetic resonance imaging and to emphasize the requirement for quality assurance and for a comprehensive study of the scanner's characteristics.

Stereotactic localization using magnetic resonance imaging

A phantom study has been carried out to assess the accuracy of stereotactic localisation, using magnetic resonance imaging. The stereotactic coordinates of an array of Perspex rods within the phantom were determined and compared with measured values, in a series of transverse, coronal and sagittal images. In the transverse plane, the maximum errors experienced were X = 2.3 mm and Y = 10.7 mm. If the third fiducial plate, at the front of the frame, were not used in the scaling of the images, there was considerable improvement in the Y direction (maximum error Y = 2.1 mm). However, some deterioration in the accuracy in the X direction resulted, particularly at the extremes of Z (maximum error X = 3.5 mm). In the coronal plane, the maximum errors were X = 1.8 mm and Z = 8.0 mm. With the third plate off, the errors decreased to X = 1.9 mm and Z = 3.3 mm. In the sagittal plane, the maximum errors recorded were Y = 1.1 mm and Z = 7.5 mm. It is not possible to calibrate in this plane without the third plate.