Biomedical subjects

Timothy Solberg

Publications and source records attributed to Timothy Solberg.

10 recordsLinked to original sources

PubMed2006

Multi-institutional clinical experience with the Calypso System in localization and continuous, real-time monitoring of the prostate gland during external radiotherapy.

PURPOSE: To report the clinical experience with an electromagnetic treatment target positioning and continuous monitoring system in patients with localized prostate cancer receiving external beam radiotherapy. METHODS AND MATERIALS: The Calypso System is a target positioning device that continuously monitors the location of three implanted electromagnetic transponders at a rate of 10 Hz. The system was used at five centers to position 41 patients over a full course of therapy. Electromagnetic positioning was compared to setup using skin marks and to stereoscopic X-ray localization of the transponders. Continuous monitoring was performed in 35 patients. RESULTS: The difference between skin mark vs. the Calypso System alignment was found to be >5 mm in vector length in more than 75% of fractions. Comparisons between the Calypso System and X-ray localization showed good agreement. Qualitatively, the continuous motion was unpredictable and varied from persistent drift to transient rapid movements. Displacements > or =3 and > or =5 mm for cumulative durations of at least 30 s were observed during 41% and 15% of sessions. In individual patients, the number of fractions with displacements > or =3 mm ranged from 3% to 87%; whereas the number of fractions with displacements > or =5 mm ranged from 0% to 56%. CONCLUSION: The Calypso System is a clinically efficient and objective localization method for positioning prostate patients undergoing radiotherapy. Initial treatment setup can be performed rapidly, accurately, and objectively before radiation delivery. The extent and frequency of prostate motion during radiotherapy delivery can be easily monitored and used for motion management.

Aged↗

PubMed2006

Brainstem and trigeminal nerve changes after radiosurgery for trigeminal pain.

PURPOSE: To evaluate the significance of radiological changes on follow-up MRIs after SRS for TN. MATERIALS AND METHODS: Thirty-seven patients with follow-up MRI because of paresthesias, bilateral treatment, or failure were analyzed regarding pain outcome and complications. Mean age was 64.4 years; 14 underwent previous treatment. Twenty-nine had ETN, 5 secondary TN due to tumor or multiple sclerosis, and 3 had atypical TN. Ninety gray was prescribed for 20 patients, 70 Gy for 5, and 80/85 Gy for 2. A 5-mm collimator was used in 32 (88.9%) cases. Mean follow-up was 15 months (range, 4-52 months). RESULTS: Excellent/good pain relief was sustained in 67% of cases at 13 months' follow-up. Enhancement on MRIs was observed in 21 cases (56.75%) with nerve enhancement in 9, pons enhancement in 4, pons-nerve enhancement in 4, and tumor enhancement in 4. Magnetic resonance images were unremarkable in 16 cases. Pain recurred in 4 cases (5.5-10 months). Pons enhancement correlated with pain relief (P = .0087) but not with nerve enhancement (P = .22). Incidence of slight paresthesias was 66.6%. No anesthesia dolorosa or ophthalmologic problems were observed. Paresthesias correlated with enhancement (P = .02), but not with brainstem volume encompassed by the 20%, 30%, and 50% isodoseline (P = .689, .525, .908). Enhancement free probability at 12 months was 48.5% (Kaplan-Meier). CONCLUSIONS: Pons enhancement seems to be prognostic for pain relief without higher incidence of complications. Pons volume irradiated did not predict enhancement occurrence. Radiation delivery to the brainstem-REZ interface seems to improve pain outcome, although more paresthesias should be expected.

Adult↗

PubMed2004

Linear accelerator thalamotomy.

BACKGROUND: The capability of performing functional radiosurgery lesions in the brain using a dedicated linear accelerator (LINAC) have not yet been demonstrated. This study evaluates modern LINAC technology for the creation of a sharp, small and functionally eloquent lesion in the thalamus. METHODS: Three patients underwent thalamotomy using a dedicated linear accelerator to radiosurgery, 2 females and 1 male, ages were 52, 53, and 73 years. Two patients presented with unilateral poststroke central pain and 1 with unilateral upper extremity pain secondary to metastatic infiltration of the brachial plexus. Maximal doses varied from 150 to 200 Gy, delivered by a 5-mm diameter collimator and 5 to 8 noncoplanar arcs evenly distributed. RESULTS: All patients gained substantial relief of their pain. They were able to reduce their medications and improve their activity levels. The patient with end-stage metastatic disease died of his malignancy 2 weeks after the treatment. One patient presented with recurrence of the pain 4 months after the treatment. No clinical complications were noticed. CONCLUSIONS: A dedicated linear accelerator is able to perform a precise and circumscribed lesion in the thalamus for pain control. Moreover, it proved to be safe, because no complications were observed. For patients using chronic anticoagulant therapy or with severe disabilities caused by cardiac, pulmonary or malignant diseases, this technique represents an alternative of treatment to radiofrequency thalamotomy.

Aged↗

PubMed2004

Novalis Shaped Beam Radiosurgery of arteriovenous malformations.

OBJECT: The authors studied outcomes and complications in patients who harbored arteriovenous malformations (AVMs) and underwent stereotactic radiosurgery involving the Novalis shaped beam unit. METHODS: Between January 1998 and January 2002, 83 patients were treated with radiosurgery at University of California, Los Angeles. The mean patient age was 37.8 years. Forty-four patients completed follow up. There were 24 women. Sixteen patients underwent repeated radiosurgery. Embolization was performed in 13 patients and radiosurgery alone in 31. The mean follow-up period after embolization was 54.4+/-21.9 months and 37.4+/-14.6 months for radiosurgery alone. The mean peripheral dose was 15 Gy (range 12-18 Gy). The mean preradiosurgery lesion volume was 9.7+/-11.9 ml for radiosurgery alone and 16.2+/-11.3 ml for embolization. The AVMs in 13 patients (29.8%) were Spetzler-Martin Grade II, 12 (27.5%) were Grade III, eight (18.2%) Grade IV, and five (11.3%) were Grade V and VI each. Spetzler-Martin grade, volume, and peripheral dose were analyzed in consideration to outcome. A positive trend (p = 0.086) was observed between Spetzler-Martin grade and obliteration rate. Volume per se did not predict obliteration (p = 0.48). A peripheral dose of 18 Gy was shown to be the most important predictor for occlusion (p = 0.007). The overall obliteration rate was 52.5%. A transient complication was noticed in one case (2.3%) and but no permanent deficits due to radiosurgery have been detected so far. Three patients (6.8%) bled after radiosurgery. CONCLUSIONS: The range of the prescribed peripheral dose was narrow. An association between the mean peripheral dose of 15 Gy, high conformality, and homogeneous dose distribution permitted no permanent complications. Volume per se did not correlate with outcome. The next step will be to increase the peripheral dose shaping the beam and to achieve higher obliteration rates without increasing complications.

Adolescent↗

PubMed2004

Spinal lesions treated with Novalis shaped beam intensity-modulated radiosurgery and stereotactic radiotherapy.

OBJECT: Spinal radiosurgery was implemented to improve quality of life (QOL) in patients with malignancies. It may also be applicable to the treatment of benign lesions. METHODS: Between July 2002 and January 2004, 14 patients harboring 22 lesions were treated; 13 received single-dose stereotactic radiosurgery. Six were women. The mean age was 60.2 years (range 48-82 years). There were 11 metastases, two neurofibromas, and one meningioma. Six lesions were cervical, 10 thoracic, and six lumbar. Ten patients suffered pain, three paresthesias, two weakness, and three were asymptomatic. Seven patients underwent spinal surgery, with four receiving instrumentation. Twelve patients underwent conventional irradiation before stereotactic radiosurgery/stereotactic radiotherapy. A mean dose of 12+/-2.7 Gy (range 8-21 Gy) was prescribed to the 91% isodose line (range 85-97%). The mean tumor volume was 25+/-27.1 ml (range 0.75-91.8 ml). Treatment was planned using intensity-modulated radiosurgery (IMRS) fields in 15 cases, dynamic arcs in five, and conformal beams in two. The mean follow-up period was 6.1+/-3.9 months (range 1-16 months). Three patients became pain free and four experienced considerable relief. Weakness improved in the two patients with this preoperative symptom and the asymptomatic patients remained so. Four lesions decreased in size, five remained stable, seven progressed, and six were not followed up (two patients died before follow up). Four patients in all died, three of systemic disease and one of thoracic lesion progression. No complications due to shaped beam and IMRS/intensity-modulated radiotherapy (IMRT) techniques were observed. CONCLUSIONS: Shaped beam and IMRS/IMRT involving the Novalis system may delay neurological deterioration, improving QOL. The lack of complication suggests that higher doses can be delivered to improve the control rate in patients with metastases.

Aged↗

PubMed2003

Radiosurgery and stereotactic radiotherapy for intracranial meningiomas.

OBJECT: The authors report the evolution of linear accelerator (LINAC)-based radiosurgery in the treatment of patients with intracranial meningiomas. They describe the technical aspects as well as clinical and radiological outcomes. METHODS: The authors performed a retrospective review of 161 patients harboring 194 intracranial meningiomas treated with various types of stereotactic irradiation at their institution between May 1991 and July 2002. Clinical and radiological follow-up data (mean follow-up period 32.5 months, range 6-125 months) were obtained in 128 patients (79.5%) with 156 meningiomas (80.4%). There were 88 women and 40 men whose mean age was 57.2 years (range 18-87 years). Stereotactic irradiation was the primary treatment in 44 patients, and 84 patients underwent resection prior to radiosurgery. Stereotactic radiosurgery (SRS) was used to treat 79 lesions and fractionated stereotactic radiotherapy (SRT) was used to treat 77. The mean dose for SRS was 1567 cGy (range 1200-2285 cGy) prescribed to a mean isodose line of 66.6% (range 50-90%). Stereotactic radiotherapy was delivered using a mean dose of 4839 cGy (range 2380-5400 cGy), prescribed to a mean isodose line of 89% (range 50-90%). The mean follow-up periods were 40 and 24 months in SRS- and SRT-treated patients, respectively. Tumor control was achieved in 58 SRT-treated benign meningiomas (90%) and in 70 SRT-treated lesions (97.2%). In patients with atypical meningiomas a considerably poorer prognosis was seen. Clinical improvement or stabilization of symptoms was observed in the majority of patients. Symptomatic complications were limited to four patients (5%) treated with SRS and four (5.2%) treated with SRT. CONCLUSIONS: Stereotactic irradiation techniques have changed the neurosurgical approach to intracranial meningiomas. Either SRS or SRT delivered as a primary treatment in selected cases of skull base lesions or as an adjuvant after conservative resection has improved the management of these complex intracranial tumors.

Adolescent↗

PubMed2003

Prospective study of stereotactic radiosurgery without whole brain radiotherapy in patients with four or less brain metastases: incidence of intracranial progression and salvage radiotherapy.

This prospective study was conducted to evaluate the treatment outcome after stereotactic radiosurgery (SRS) alone with special attention to its influence on intracranial freedom from progression (FFP), local control, time to whole brain radiotherapy (WBRT), and survival. Forty-one patients with brain metastases who met the inclusion criteria were enrolled in this prospective cohort and treated by SRS alone between January 1998 and September 2001. The overall local control rate was 76%. The one year actuarial intracranial FFP was 33%. Ten patients (24%) had relapse at treated site. Twenty-three patients (56%) had intracranial progression with a median time of 4.25 months (1-24.6). Salvage radiotherapy was given in 21 patients (51%). Only 12 (29%) patients required WBRT with the median time to WBRT after SRS of 4.85 months. Nine patients (22%) underwent additional SRS at the median time of 5 months after the first procedure. The median survival was 10 months. At the time of follow up, 16 patients (39%) were still alive with a range of 6-31 months. This prospective study suggests that the omission of WBRT in the initial treatment of patients with SRS for four or less brain metastases may allow up to 70% of patients to avoid WBRT.

Adult↗

PubMed2003

Linear accelerator radiosurgery using 90 gray for essential trigeminal neuralgia: results and dose volume histogram analysis.

OBJECTIVE: To evaluate treatment of essential trigeminal neuralgia with 90 Gy delivered by a linear accelerator dedicated to radiosurgery. METHODS: This is a retrospective case series of 25 patients with essential trigeminal neuralgia treated from March 1999 to March 2001. All were treated with 90 Gy by means of a 5-mm collimator directed to the nerve root entry zone. Patient follow-up (range, 8-52 mo; median, 18 mo) was completed by an uninvolved party. Dose volume histograms of the brainstem were developed for the 20, 30, and 50% isodose lines by means of radiosurgery planning software. RESULTS: All patients obtained good to excellent pain relief with treatment. Nineteen (76%) of 25 patients achieved excellent pain relief (pain-free without medication). Six patients (24%) achieved good pain relief (50-90% reduction of pain with or without medication). Median time to pain relief was 2 months. Eight patients (32%) experienced relapse 4 to 13 months after treatment. Eight patients (32%) developed facial numbness, but none developed painful numbness. Mean brainstem volume within the 50% isodose line and occurrence of numbness was statistically significant (P = 0.03). There was no correlation between brainstem volume treated and outcome. CONCLUSION: Dedicated linear accelerator-based stereotactic radiosurgery that uses a 5-mm collimator to deliver 90 Gy to the nerve root entry zone is a safe and effective method for the treatment of essential trigeminal neuralgia. Care should be taken to limit brainstem volume included in the 50% isodose line in the treatment plan to avoid facial numbness.

Aged↗

PubMed2003

Dedicated linear accelerator radiosurgery for the treatment of trigeminal neuralgia.

OBJECT: In this study the authors evaluate the efficacy of and complications associated with dedicated linear accelerator (LINAC) radiosurgery for trigeminal neuralgia (TN). METHODS: Between August 1995 and February 2001, 60 patients whose median age was 66.1 years (range 45-88 years) were treated with dedicated LINAC radiosurgery for TN. Forty-one patients (68.3%) had essential TN, 12 (20%) had secondary facial pain, and seven (11.7%) had atypical features. Twenty-nine patients (48.3%) had undergone previous surgical procedures. Radiation doses varied between 70 and 90 Gy (mean 83.3 Gy) at the isocenter, with the last 35 patients (58.3%) treated with a 90-Gy dose. A 5-mm collimator was used in 45 patients (75%) and a 7.5-mm collimator in 15 patients (25%). Treatment was focused at the nerve root entry zone. At last follow up (mean follow-up period 23 months, range 2-70 months), 36 (87.8%) of the 41 patients with essential TN had sustained significant pain relief (good plus excellent results). Twenty-three patients (56.1%) were pain free without medication (excellent outcome), 13 (31.7%) had a 50 to 90% reduction in pain with or without medication (good outcome), and five (12.2%) had minor improvement or no relief. Of 12 patients with secondary facial pain, significant relief was sustained in seven patients (58.3%); worse results were found with atypical pain. Fifteen (25%) of the 60 patients experienced new numbness postprocedure; no other significant complications were found. Pain relief was experienced at a mean of 2.7 months (range 0-12 months). CONCLUSIONS: Dedicated LINAC radiosurgery is a precise and effective treatment for TN.

Aged↗

PubMed2003

How have hospital investments navigated troubled waters?

The dismal stock-market returns of the past few years compel hospitals to examine their investment policies. The asset-allocation decisions of hospital CFOs and trustees generally are based on market trends. Some of their key concerns include volatility of investment returns, lack of internal resources for investment support, trustee and committee fiduciary and investment education, and retaining experienced investment advisory services.

Capital Financing↗