Biomedical subjects

Jack Rock

Publications and source records attributed to Jack Rock.

9 recordsLinked to original sources

PubMed2007

Partial volume tolerance of the spinal cord and complications of single-dose radiosurgery.

BACKGROUND: Spine radiosurgery causes a rapid dose fall-off within the spinal cord. The tolerance of partial volume of the spinal cord may determine the extent of clinical application. The study analyzed the partial volume tolerance of the human spinal cord to single fraction radiosurgery. METHODS: A total of 230 lesions with spine metastases in 177 patients were treated with radiosurgery with single fraction of 8 to 18 Gy, prescribed to the 90% isodose line that encompassed the target volume. Spinal cord volume was defined as 6 mm above and below the radiosurgery target volume. Spinal cord dose was calculated from the radiation dose/spinal cord volume histogram and correlated with clinical/neurological status and radiographic studies. Median follow-up was 6.4 months (range, 0.5-49 months). The 1-year survival rate was 49%. RESULTS: The average spinal cord volume defined at the treated spinal segment was 5.9 +/- 2.2 mL. The average dose to the 10% spinal cord volume was 9.8 +/- 1.5 Gy, calculated from the dose-volume histogram in the group of 18 Gy prescribed dose. The spinal cord volume that received higher than 80% of the prescribed dose was 0.07 +/- 0.10 mL, which represented 1.3 +/- 1.8% of the cord volume. Among the 86 patients who survived longer than 1 year there was 1 case of radiation-induced cord injury after 13 months of radiosurgery. There were no other cases of spinal cord sequelae. CONCLUSIONS: Whereas the maximum spinal cord tolerance to single-dose radiation is not known, partial volume tolerance of the human spinal cord is at least 10 Gy to 10% of the spinal cord volume defined as 6 mm above and below the radiosurgery target.

Adolescent↗

PubMed2006

Tentorial schwannoma: a case report and review of the literature.

INTRODUCTION: Schwannomas are most often found in association with the eighth cranial nerve, but may also arise from any other cranial nerve. They are rarely found in an intra-parenchymal location. Unusual locations for intracranial schwannomas have also been reported in association with neurofibromatosis. CLINICAL PRESENTATION: A 23-year-old male without von Recklinghausen's disease presented with intermittent dizziness and difficulty swallowing. Past medical history was significant for a motor vehicle accident (MVA) without loss of consciousness 6 months prior. Magnetic resonance imaging revealed a large tentorial-based tumor. At surgery the origin of the tumor was clearly the tentorium, and while the trigeminal nerve was displaced, it easily separated from the mass. There was no attachment to any other cranial nerve in the immediate vicinity and postoperative cranial nerve examination was unremarkable. Pathological review was consistent with schwannoma. CONCLUSION: While there are few reported cases of tentorial-based schwannoma, these tumors have been noted in unusual locations within the intracranial vault, and clinicians should be aware of this diversity of origin.

Adult↗

PubMed2005

Direct infiltration of brainstem glioma along the cranial nerves.

The authors describe a case of a low-grade brainstem glioma extending along the cranial nerves without any evidence of leptomeningeal spread. The tumor extended directly along the VII-VIIIth cranial nerve complex and also along the trigeminal nerve, which is quite an unusual characteristic of the glial tumors.

Adult↗

PubMed2004

Patterns of failure after single-dose radiosurgery for spinal metastasis.

OBJECT: Single-dose radiosurgery for solitary spinal metastases can achieve rapid and durable pain control. This study was conducted to determine the patterns of failure after spinal radiosurgery. METHODS: Forty-nine patients with 61 solitary spinal metastases underwent radiosurgery between May 2001 and May 2003. Single-dose radiosurgery (10-16 Gy) was delivered only to the involved spinal segments. The authors undertook a retrospective review of clinical notes, including patient questionnaires and radiological studies (computerized tomography or magnetic resonance imaging), to analyze patterns of failure following radiosurgery with regard to the pain and tumor control. Complete and partial pain relief was achieved in 85% of the lesions treated. Relapse of pain at the treated site was noted in 7%. Radiologically, lesions progressively metastasized to the immediately adjacent spines in 5%. These patients also had progressive primary and/or other systemic metastatic diseases. CONCLUSIONS: Spine-related pain control/reduction was excellent. Tumor recurrence at the treated segment and progression to the immediately adjacent region were rare. The results support the use of spinal radiosurgery as an effective treatment option for solitary spinal metastasis.

Adult↗

PubMed2004

Image-guided procedures for intensity-modulated spinal radiosurgery. Technical note.

Radiosurgery for brain tumors has been well established in the radiation oncology and neurosurgery fields. Radiosurgery of extracranial tumors such as those involving the spine is, however, still in the early stage because of difficulties in patient immobilization and organ motion. The authors describe an image-guided procedure for intensity-modulated spinal radiosurgery that was developed at Henry Ford Hospital.

Algorithms↗

PubMed2003

Image-guided and intensity-modulated radiosurgery for patients with spinal metastasis.

BACKGROUND: Radiosurgery can deliver a single, large radiation dose to a localized tumor using a stereotactic approach and hence, requires accurate and precise delivery of radiation to the target. Of the extracranial organ targets, the spine is considered a suitable site for radiosurgery, because there is minimal or no breathing-related organ movement. The authors studied spinal radiosurgery in patients with spinal metastases to determine its accuracy and precision. METHODS: The spinal radiosurgery program was based on an image-guided and intensity-modulated, shaped-beam radiosurgical unit. It is equipped with micromultileaf collimators for beam shaping and radiation intensity modulation and with a noninvasive, frameless positioning device that uses infrared, passive marker technology together with corroborative image fusion of the digitally reconstructed image from computed tomography (CT) simulation and orthogonal X-ray imagery at the treatment position. These images were compared with the port films that were taken at the time of treatment to determine the accuracy of the isocenter position. Clinical feasibility was tested in 10 patients who had spinal metastasis with or without spinal cord compression. The patients were treated with fractionated external beam radiotherapy followed by single-dose radiosurgery as a boost (6-8 grays) to the most involved portion of the spine or to the site of spinal cord compression. RESULTS: The accuracy for the isocenter was within 1.36 mm +/- 0.11 mm, as measured by image fusion of the digitally reconstructed image from CT simulation and the port film. Clinically, the majority of patients had prompt pain relief within 2-4 weeks of treatment. Complete and partial recovery of motor function also was achieved in patients with spinal cord compression. The radiation dose to the spinal cord was minimal. The maximum dose of radiation to the anterior edge of the spinal cord within a transverse section, on average, was 50% of the prescribed dose. There was no acute radiation toxicity detected clinically during the mean follow-up of 6 months. CONCLUSIONS: Image-guided, shaped-beam spinal radiosurgery is accurate and precise. Rapid clinical improvement of pain and neurologic function also may be achieved. The results indicate the potential of spinal radiosurgery in the treatment of patients with spinal metastasis, especially those with solitary sites of spine involvement, to increase the prospects of long-term palliation.

Feasibility Studies↗

PubMed2002

Radiosurgical treatment for Ewing's sarcoma of the lumbar spine: case report.

STUDY DESIGN: Case report. OBJECTIVES: The objective of this study was to document the long-term follow-up of a single case. SUMMARY OF BACKGROUND DATA: Radiosurgery is potentially a useful therapeutic option for spinal tumors. The authors present the unusual case of a patient with recurrent extraosseous Ewing's sarcoma of the lumbar spine, who experienced excellent clinical, radiographic, and oncologic response without complications after treatment with dedicated Novalis Shaped Beam Radiosurgery (Brain Lab, Inc.). METHODS: Observational. RESULTS: We observed excellent clinical and oncologic control at 1-year posttreatment. CONCLUSION: Radiosurgery may be a valuable treatment option for recurrent spinal tumors.

Bone Neoplasms↗

PubMed2002

A technique of intensity-modulated radiosurgery (IMRS) for spinal tumors.

This study is to demonstrate the feasibility of spinal radiosurgery using an image-guided intensity-modulated radiosurgical (IMRS) procedure. A dedicated Novalis shaped beam surgery unit equipped with a built-in micro-multileaf collimator (mMLC) with a single 6 MV photon beam was used. Each patient was simulated in the supine position using an AcQsim CT simulator with infrared sensitive markers for localization. A variety of different treatment plans were developed, but the most common plan was the use of seven coplanar intensity-modulated beams to minimize radiation to critical organs such as the spinal cord and kidneys. An automatic localization device based on infrared and video cameras was used to guide the initial patient setup. Two keV x-ray imaging systems were used to identify potential deviations from the planned isocenter. A total of 25 patients with spinal tumors have been treated using this procedure with a single prescription dose ranging from 6 to 12 Gy. The final verification images indicated that the average isocenter deviation from the planned isocenter was within 2 mm. The phantom verification of isocenter doses indicated that the average deviation of measured isocenter doses from the planned isocenter doses for all patients treated with intensity-modulated beams was less than 2%. Film dose measurement in a phantom study demonstrated good agreement of above 50% isodose lines between the planned and measured results. Preliminary experience shows that precision delivery of high dose radiation could be administered to the planned target volume while the dose to the critical organs is kept within tolerable limits.

Computer Simulation↗

PubMedDate not supplied

Quality of life in patients with pituitary tumors: a preliminary study.

Patients with pituitary tumors frequently complain of quality of life problems despite normal hormonal blood levels. The goals of the study were to determine whether the sickness-related quality of life reported by these patients was poorer than that expected by the general population and whether some of these complaints and areas of dysfunction were more troublesome than others. Forty-three patients from a southeast Michigan pituitary disorders support group volunteered to complete a survey focusing on demographic, disease data and common complaints plus the Sickness Impact Profile (SIP). The results indicated that mental and physical fatigue were the most troublesome symptoms with sleep and libidinal complaints also of significant concern. The SIP indicated significant discontent among patients with regard to overall quality of life. Although this observational investigation seemed to underscore the fact that patients with pituitary tumors have a decreased quality of life despite apparently normal hormonal status, further subgroup analysis and subsequent surveys will be required to determine the actual significance of these findings.

Adult↗