Radiosurgery plus whole-brain radiation therapy for brain metastases.
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Brain Neoplasms↗
Biomedical subjects
Lawrence S Chin
Publications and source records attributed to Lawrence S Chin.
Comments about the prospective randomized trial by Aoyama et al.
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Antineoplastic Protocols↗
Concomitant GRID boost for Gamma Knife radiosurgery.
We developed an integrated GRID boost technique for Gamma Knife radiosurgery. The technique generates an array of high dose spots within the target volume via a grid of 4-mm shots. These high dose areas were placed over a conventional Gamma Knife plan where a peripheral dose covers the full target volume. The beam weights of the 4-mm shots were optimized iteratively to maximize the integral dose inside the target volume. To investigate the target volume coverage and the dose to the adjacent normal brain tissue for the technique, we compared the GRID boosted treatment plans with conventional Gamma Knife treatment plans using physical and biological indices such as dose-volume histogram (DVH), DVH-derived indices, equivalent uniform dose (EUD), tumor control probabilities (TCP), and normal tissue complication probabilities (NTCP). We found significant increase in the target volume indices such as mean dose (5%-34%; average 14%), TCP (4%-45%; average 21%), and EUD (2%-22%; average 11%) for the GRID boost technique. No significant change in the peripheral dose coverage for the target volume was found per RTOG protocol. In addition, the EUD and the NTCP for the normal brain adjacent to the target (i.e., the near region) were decreased for the GRID boost technique. In conclusion, we demonstrated a new technique for Gamma Knife radiosurgery that can escalate the dose to the target while sparing the adjacent normal brain tissue.
Algorithms↗
Long-term control after resection and gamma knife surgery of an intracranial clear cell meningioma: case report.
Clear cell meningioma (CCM) is a rare variant of meningioma characterized by sheets of polygonal cells with clear cytoplasm, a feature attributable to its high glycogen content. Authors have described its propensity to recur and metastasize despite its benign pathological characteristics. Clinical response to radiation in these reports has varied. The authors present the case of a 7-year-old girl with a large petroclival CCM who underwent a staged subtotal resection and subsequent gamma knife surgery (GKS). Initially, the residual tumor decreased in size, but 6 years later, it had regrown (9 mm in size). A second GKS treatment was performed and the mass completely regressed without further complication. The findings in this case suggest that GKS is a safe and effective adjunct for residual and recurrent CCM after resection. The delayed recurrence also emphasizes the importance of undertaking close follow-up examination after treating this potentially aggressive variant of meningioma.
Cerebellopontine Angle↗
Factors predicting local tumor control after gamma knife stereotactic radiosurgery for benign intracranial meningiomas.
PURPOSE: To determine the long-term outcomes and prognostic factors in benign intracranial meningiomas treated with gamma knife stereotactic radiosurgery (GK-SRS). METHODS AND MATERIALS: Between 1992 and 2000, 162 patients with benign meningiomas were treated with GK-SRS at the University of Maryland Medical Center. Complete follow-up was available in 137 patients. All patients underwent magnetic resonance imaging (MRI)-based treatment planning. Serial MRIs and clinical exams were performed to assess tumor response. GK-SRS was the primary treatment in 85 patients (62%), whereas 52 patients (48%) had prior surgical resections. The median prescribed dose was 14 Gy (range, 4-25 Gy) to the 50% isodose line. The median tumor volume, treatment volume, and conformity index were 4.5 cc (range, 0.32-80.0 cc), 6.3 cc (range, 1.0-75.2 cc), and 1.34 (range, 0.65-3.16), respectively. The median follow-up for the entire cohort was 4.5 years (range, 0.33-10.5 years). The following factors were included in the statistical analysis for disease-free survival (DFS) and overall survival (OS): sex, age, dose, gross tumor volume (GTV), conformity index (CI), and dural tail coverage. RESULTS: Serial MRI analysis was available in 121 patients (88.3%). Decrease in tumor size was observed in 34 patients (28.1%), whereas there was no change in 77 patients (63.6%), for a crude radiographic control rate of 91.7%. Increase in tumor size was seen in 10 patients (8.3%). New neurologic deficits attributed to the treatment developed in 10 patients (8.3%). The mean DFS and OS for the entire cohort are 4.6 years and 5.0 years, respectively. The 5-year actuarial DFS and OS were 86.2% and 91.0%, respectively. Univariate analysis revealed GTV, sex, CI, and dural tail treatment to be significant prognostic factors. Patients with GTV < or =10 cc also had longer survivals, with the 5-years DFS and OS of 91.9% vs. 68.0% (p = 0.038) and 100% vs. 59.7% (p = 0.0001), respectively. The 5-years actuarial DFS and OS for females vs. males were 90.2% vs. 74.2% (p = 0.0094) and 91.6% vs. 89.1% (p = 0.016), respectively. Patients with CI > or =1.4 achieved a longer DFS, with a 5-year DFS of 95.2% vs. 77.3% (p = 0.01). Patients who had the dural tail treated also had higher 5-year DFS (96.0% vs. 77.9%, p = 0.038). Patients with lower conformity (i.e., CI > or =1.4) tended to have the dural tail covered in the prescription isodose line (p = 0.04). The only factor significant in the multivariate analysis was for patients with GTV >10 cc, who had a worse DFS (hazard ratio 4.58, p = 0.05). CONCLUSIONS: This report adds to the literature that supports the efficacy and safety of GK-SRS in the management of patients with benign intracranial meningiomas. Our report identified male patients, patients with a CI <1.4, and tumor size greater than 10 cc to have a worse prognosis. Patients who were treated with less conformal plans to cover the dural tail had better outcomes. Our data clearly demonstrate the need to adequately cover the dural tail in patients treated with GK-SRS for benign intracranial meningiomas.
Adolescent↗
Gamma knife surgery for trigeminal neuralgia: outcome, imaging, and brainstem correlates.
PURPOSE: To review our results with gamma knife surgery (GKS) in the treatment of trigeminal neuralgia (TN), and to determine whether pain relief, medication usage, and the development of facial numbness are affected by trigeminal nerve compression, MRI imaging quality, or brainstem radiation dose. METHODS AND MATERIALS: One hundred twelve patients with TN refractory to medical or surgical management were treated at the University of Maryland Gamma Knife Center between June 1996 and July 2001. Patients were treated using a 4-mm shot to the trigeminal nerve, at a point 2-4 mm anterior to the root entry zone of the nerve into the pons. The median dose prescribed was 75 Gy (range, 60-80 Gy). T1- and T2-weighted, axial, 1.5-mm-thick MRI images were obtained using three-dimensional gradient echo acquisition after contrast injection for treatment planning. MRI images were evaluated for imaging quality (i.e., the adequacy of visualization of the affected prepontine trigeminal nerve), the presence of trigeminal nerve compression, and the brainstem dose. Follow-up data were obtained via telephone interviews, and patients were asked to rate their pre-GKS and post-GKS pain using the Barrow Neurological Institute (BNI) Pain Intensity Scale. Patients were also asked about side effects from GKS and were asked to rate any facial numbness on the BNI Facial Numbness Scale. Medication use, time to pain response, and duration of relief were also evaluated. RESULTS: Ninety-six patients who had follow-up data were included in the analysis. Eighty-six patients (89.6%) responded to GKS with an improvement in BNI pain class. Ten patients (10.4%) were found to have an MRI of poor quality, 30 (31.3%) fair quality, and 56 (58.3%) good quality. Forty-two (43.8%) received 10% of the maximal dose to the brainstem edge, whereas 54 (56.2%) received 20%. Eleven (11.5%) patients were found to have obvious nerve compression by MRI. Imaging quality (p = 0.1863), presence of compression (p = 0.1147), and brainstem dose (p = 0.3168) did not correlate with treatment response. There was also no correlation between these variables (MRI quality, compression, and brainstem dose) and medication use (p = 0.5372, p = 0.0913, p = 0.6832, respectively). Facial numbness was the only side effect experienced. Thirteen patients reported varying degrees of facial numbness, but there was no correlation between imaging quality (p = 0.0600), brainstem dose (p = 0.6773), and presence of compression (p = 0.5785) with the development of facial numbness. CONCLUSIONS: Gamma knife surgery is effective in the treatment of TN and has a favorable side effect profile. Treatment response and the development of facial numbness do not correlate with MRI imaging quality, presence of nerve compression, or radiation dose to the brainstem.
Adult↗
Repeat gamma knife radiosurgery for refractory or recurrent trigeminal neuralgia: treatment outcomes and quality-of-life assessment.
PURPOSE: Stereotactic radiosurgery (SRS) has become a minimally invasive treatment modality for patients with refractory trigeminal neuralgia. It is unclear, however, how best to treat patients with pain that is refractory or recurrent after initial SRS. We report on treatment outcomes and quality of life for patients treated with repeated SRS for refractory or recurrent trigeminal neuralgia. METHODS AND MATERIALS: Between June 1996 and June 2001, 112 patients with trigeminal neuralgia were treated with SRS at the University of Maryland Medical Center. Eighteen patients underwent repeat SRS 3-42 months (median, 8 months) after initial radiosurgery because of unsatisfactory or unsustained pain relief. Patients received a median prescription dose of 75 and 70 Gy, respectively, for the first and second treatments. Self-reports of pain control were assessed with a standard questionnaire containing the complete Barrow Neurologic Institute Pain Scale. RESULTS: The median follow-up was 37.5 months (range, 12-68 months) after initial SRS and 24.5 months (range, 6-65 months) after repeat SRS. For the 18 patients in this series, the percentage of patients reporting excellent, good, fair, and poor responses after the initial and repeat SRS was 50%, 28%, 6%, and 16% and 45%, 33%, 0%, and 22%, respectively. None of the 3 patients with pain refractory to initial SRS responded to repeat SRS. Among those with recurrent pain after initial SRS, 14 patients (93%) achieved excellent or good pain outcomes after repeat SRS. The actuarial analysis revealed a 1-year recurrence rate of 22%, with no patients reporting recurrent pain after 9 months of follow-up. Two patients (11%) reported new or increased facial numbness after retreatment, which was described as bothersome by one. Repeat SRS resulted in a median 60% improvement in quality of life, and 56% of patients believed that the procedure was successful. CONCLUSION: Despite a modest dose reduction, repeat SRS provided similar rates of complete pain control as the initial procedure, but was not effective for patients with no response to initial treatment. Repeat SRS was more efficacious for those patients who experienced longer periods of pain relief after the initial SRS. The incidence of complications was not significantly different from that observed for initial SRS. In this series, most patients had significant improvements in quality of life.
Adult↗
Long-term survival after gamma knife radiosurgery for primary and metastatic brain tumors.
In this paper, we studied factors related to long-term survival after gamma knife radiosurgery (GKS) for primary and metastatic brain tumors. We examined all cases of brain metastases and malignant glioma treated with GKS between September 1994 and December 1998. All patients with survival exceeding 2 years were studied retrospectively using prospectively acquired data. A total of 22 patients, with an average age of 56, were identified, which accounts for 11% of the total patients treated during this time interval. Seventeen of 22 are still alive with a mean follow-up of 48 months. Sixteen patients had metastatic tumors, whereas 6 had a malignant glioma. Thirteen of 15 patients with metastases had a controlled primary site, and the other 2 patients did not have a primary site identified. These 2 patients were among the 3 that died during the follow-up period. Fourteen patients developed symptomatic radiation necrosis by MRI criteria with 4 confirmed by biopsy. Quality-of-life factors were assessed in 20 of 22 patients using a modified Spitzer scale, which showed a high level of functioning in all of the long-term survivors (mean score 8.65 of 10), and only 1 patient had a Karnofsky Performance Score of less than 70. We conclude that radiosurgery provides a noninvasive and effective way of controlling brain tumors, while preserving quality of life.
Adult↗
Clinical implementation of an automated planning system for gamma knife radiosurgery.
PURPOSE: To evaluate an automated treatment planning system for gamma knife radiosurgery. This planning system was developed in our clinic and is now in routine clinical use. The system simultaneously optimizes the shot sizes, locations, and weights. It also guides the user in selecting the total number of radiation shots. METHODS AND MATERIALS: We assessed the clinical significance of the automated system by comparing an optimized plan with a manual plan for 10 consecutive patients treated at our gamma knife facility. Each treatment plan was analyzed using dose-volume histograms in conjunction with the conformity index, the minimum target dose, and the integral normal tissue dose. RESULTS: On average, the treatment plan produced by the inverse planning tool provided an improved conformity index, a higher minimum target dose, and a reduced volume of the 30% isodose line as compared to the corresponding plan developed by an experienced physician. An optimized treatment plan can typically be produced in 10 min or less. CONCLUSIONS: The automated planning system consistently provides a high-quality treatment plan while reducing the time required for gamma knife treatment planning.
Humans↗
Radiosurgical treatment of trigeminal neuralgia: evaluating quality of life and treatment outcomes.
PURPOSE: To assess the safety, efficacy, and quality of life (QOL) associated with radiosurgical treatment for trigeminal neuralgia (TN). METHODS AND MATERIALS: Between June 1996 and June 2001, 112 patients with TN refractory to medical or surgical management were treated with gamma knife radiosurgery (GKRS) at the University of Maryland Medical Center. A median prescription dose of 75 Gy (range: 70-80 Gy) was delivered to the involved trigeminal nerve root entry zone. Treatment outcomes were assessed through patient self-reports of pain control and medication usage during follow-up visits. In addition, patients responded to a standard questionnaire containing the Barrow Neurologic Institute Pain Scale (BNI) and selected sections of the McGill Pain Scale. Treatment outcomes and objective quality of life measures were also addressed. RESULTS: Ninety-six patients (86%) completed questionnaires for a median follow-up of 30 months (range: 8-66 months). Seventy-four patients (77%) reported pain relief occurring after a median of 3 weeks (range: 0-24 weeks) after GKRS. A decrease in medication usage was noted in 66% of patients. Actuarial analysis demonstrated 1-year, 2-year, and 3-year recurrence rates of 23%, 33%, and 39%, respectively. Response to treatment was associated with lack of prior surgical treatment (p = 0.03) and less than 50 months' pain duration before GKRS (p = 0.04). Patients who described their TN pain as more severe than their worst non-TN headache pain (McGill Pain Scale IV-V vs. I-III) were also more likely to respond to treatment (p < 0.001). Seven (7.3%) patients reported new or increased trigeminal dysfunction; however, only 3.1% reported these symptoms as bothersome (BNI III-IV). Patients with sustained pain relief reported an average of 100% improvement in their QOL as a direct result of pain relief after GKRS, and 100% believed that the procedure was successful. Furthermore, among those patients with temporary pain relief and subsequent recurrence, 65% felt their treatment was a success with an average of 80% improvement in their QOL. CONCLUSIONS: GKRS provides significant pain relief and improves QOL in the majority of patients treated for TN, with few bothersome side effects. Patients with both temporary and sustained responses to treatment realized significant improvements in QOL after GKRS, and considered their treatment successful. Longer follow-up of these patients may reveal additional recurrences highlighting the importance of studies evaluating repeat GKRS and optimization of current treatment techniques and patient selection.
Adult↗
Stereotactic radiosurgery for meningiomas.
Meningiomas are benign tumors attached to the dura that typically have a slow growth rate. After gliomas, they are the most common primary tumor of the brain. They are ideal radiobiological targets because single-fraction radiation has a high biologically effective dose. Furthermore, a highly conformal radiation plan can provide effective treatment to the tumor while sparing the surrounding brain. Meningioma control rates range from 90 to 95%, and the risk of morbidity is low. Radiosurgery is an excellent treatment for asymptomatic, small- to moderate-sized meningiomas. It is also ideal for patients with incompletely resected meningiomas, recurrent meningiomas, and risk factors precluding conventional surgery.
Follow-Up Studies↗
Okadaic-acid-induced apoptosis in malignant glioma cells.
OBJECT: Okadaic acid (OA), a potent protein phosphatase inhibitor, has been known to induce apoptosis in a variety of cell types. The authors attempted to characterize further this model by identifying proteins involved in this form of programmed cell death. METHODS: Cellular proliferation was assessed using a colorimetric nonradioactive proliferation assay and cell counts. Apoptosis was determined by fluorescent microscopy. Activation of the mitogen-activated protein kinase (MAPK) pathways was determined by immunoprecipitation of extracellular signal-regulated kinase (ERK), c-Jun-N-terminal kinase (JNK), and p38 followed by in vitro kinase assays. Western blot analyses were conducted to show inhibitory-kappaB (IkappaB) phosphorylation and degradation as well as Bax upregulation. The binding of nuclear factor-kappaB (NFkappaB) was shown by electrophoretic mobility shift assay. Okadaic acid induced cell death in T98G human malignant cell lines (50% inhibiting concentration = 20-25 nM). In T98G cells YO-PRO fluorescent staining was identified, thus indicating an apoptotic mechanism with a smaller percentage of cells undergoing necrotic cell death. Additionally OA induced JNK and MAPK activities in a time-dependent manner, increased the expression of Bax, and increased IkappaB phosphorylation and NFkappaB activation. There was a temporal correlation between these subcellular events and the detection of apoptosis morphology in glioma cells. CONCLUSIONS: The authors believe that OA acts by blocking dephosphorylation events, thus activating apoptotic pathways through ERK and JNK activity. Additionally Bax, IkappaB and NFkappaB may also play a role in regulating these pathways.
Active Transport, Cell Nucleus↗
Gamma knife stereotactic radiosurgery for synchronous versus metachronous solitary brain metastases from non-small cell lung cancer.
A retrospective study was conducted analyzing the clinical outcome and various prognostic factors in patients treated with gamma knife stereotactic radiosurgery (GK-SRS) for solitary brain metastasis from non-small cell lung carcinoma (NSCLC). A total of 72 patients from June of 1992 to January of 1999 were treated. All patients received GK-SRS to a median dose of 18Gy, with 45 patients receiving additional whole-brain radiation therapy. No one had evidence of extra-cranial metastasis at the time of diagnosis of brain metastases. The median follow-up was 15.7 months for the entire population and 99.5 months for those who were alive at the last follow-up. Univariate and multivariate analyses were used to test the impact of various prognostic factors on survival. The median and 5-year actuarial survivals for the entire cohort were 15.7 months and 10.4%, respectively. The presence of a metachronous versus a synchronous brain metastasis was the only factor significant in the univariate (P=0.045) and multivariate (P=0.002) analyses. Patients with metachronous solitary brain metastases had a significant median survival advantage compared to those with synchronous metastases (33.3 months versus 8.6 months, P=0.001). However, there was no statistically significant difference in median survival from the time of metastasis when treated with GK-SRS in these groups (12.5 months versus 8.4 months, P=0.50). The addition of WBRT did not improve overall survival (12.0 months versus 7.7 months, P=0.73). The 5-year actuarial survival for the metachronous and synchronous groups were 13.2 and 8.1%, respectively. In conclusion, patients presenting with a solitary metachronous brain metastasis from NSCLC achieved longer survivals than those with a synchronous metastasis. The tail in the survival curves demonstrates that a prolonged survival may be attained in patients with solitary metastases from NSCLC. This study adds to the growing body of literature that supports the use of SRS in the management of this patient population.
Brain Neoplasms↗
Concomitant boost of stratified target area with gamma knife radiosurgery: a treatment planning study.
Conventional Gamma Knife Stereotactic Radiosurgery (GKSRS) has been focused on delivering a single peripheral dose to the gross target volume based on the anatomic information derived from the magnetic resonance or computed tomography (CT) studies. In this study, we developed a treatment planning approach that allows a boost dose to be delivered concomitantly to the desired subtarget area while maintaining the peripheral isodose coverage of the target volume. The subtarget area is defined as the high-risk or the tumor burden areas based on the functional imaging information such as the magnetic resonance spectroscopy (MRS) studies or the physician's clinical diagnosis. Treatment plan comparisons were carried out between the concomitant boost plans and the conventional treatment plans using dose volume histogram (DVH), tissue volume ratio (TVR), and the maximum dose to the peripheral dose ratio (MD/PD) analysis. Using the concomitant boost approach, more conformal and higher dose was delivered to the desired subtarget area while maintaining the peripheral isodose coverage of the gross target volume (GTV). Additionally, the dose to the normal brain tissue was found to be equivalent between the concomitant boost plans and the conventional plans. As a result, we conclude that concomitant boost of a stratified target area is feasible for GKSRS.
Brain Neoplasms↗
Stereotactic radiosurgery for benign neoplasms.
Over the last decade, the use of stereotactic radiosurgery (SRS) for the treatment of intracranial lesions has grown significantly. In addition to malignant brain tumors and vascular malformations, benign tumors have also been treated with SRS. Although surgical resection has long been considered the gold standard in the management of such benign lesions, the outcomes of SRS in various benign neoplasms appears to be comparable. In this review, we will examine the literature as it pertains to the treatment of benign brain tumors with SRS. Of particular note, we will examine the results of SRS in acoustic neuromas, meningiomas, pituitary adenomas, and other benign tumors.
Adenoma↗
Tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis in established and primary glioma cell lines.
OBJECT: Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF cytokine family, which mediates programmed cell death (apoptosis) selectively in tumor cells. The selective tumoricidal activity of TRAIL is believed to be modulated by agonistic (DR4 and DR5) and antagonistic receptors (DcR1 and DcR2), which appear to compete for ligand binding. Because TRAIL is expressed in a wide range of tissues, including brain, kidney, and spleen, and seems consistently to induce cell death in tumor cells, the cytokine has been identified as a promising approach for selectively inducing tumor cell death. In this study, the authors examine the importance of TRAIL's receptors in both its selectivity for tumor cells and its ability to induce apoptosis. METHODS: The authors first examined sensitivity to TRAIL and expression of TRAIL receptors in four established and four primary cultured glioma cell lines by using viability and fluorescent apoptosis assays. They then evaluated DR5 expression and JNK, caspase 3, and caspase 7 activation by conducting immunoblot analyses. Reverse transcriptase-polymerase chain reaction (RTPCR) was performed to study expression of DR4, DR5, DcR1, and DcR2. The DR5 transcripts from one TRAIL-sensitive, one partially TRAIL-resistant, and one TRAIL-resistant cell line were subsequently sequenced. The expression of TRAIL receptors in normal and glial brain tumor pathological specimens were then compared using immunohistochemistry. Finally, to study the direct effects of DR5 on glioma cells, the authors conducted transient and stable transfections of the full-length DR5 transcript into glioma cells with and without preestablished overexpression of the antiapoptotic gene bcl-2. The established glioma cell lines T98G and U87MG, and all primary cell lines, were apoptotic at greater than or equal to 100 ng/ml TRAIL. The A172 cells, by contrast, were susceptible only with cycloheximide, whereas U373MG cells were not susceptible to TRAIL. The JNK, caspase 3, and caspase 7 activity evaluated after treatment with TRAIL showed that TRAIL-sensitive cell lines exhibited downstream caspase activation, whereas TRAIL-resistant cells did not. The DR5 sequences in T98G, A172, and U373MG cell lines were identical to published sequences despite these differences in sensitivity to TRAIL. The RT-PCR performed on extracts from the eight glioma cell lines showed that all expressed DR5. Immunohistochemistry revealed ubiquitous expression of DR5 in glioma specimens, with an associated lack of decoy receptor expression. Normal brain specimens, by contrast, stained positive for both DR5 and DcR1. Overexpression of DR5 under both transfection conditions resulted in cell death in all three cell lines. The previously seen resistance of U373 cells to TRAIL was not observed. Apoptotic cell death was confirmed using DNA fragmentation in T98G cell lines and fluorescent miscroscopy in all cell lines. The T98G cells stably transfected with bcl-2 before DR5 overexpression were protected from cell death. CONCLUSIONS: The authors conclude that DR5 represents a promising new approach to directly activating the intrinsic caspase pathway in glioma cells. The fact that TRAIL-resistant gliomas do not express decoy receptors suggests a mechanism of resistance unique from that proposed for normal tissues. The overexpression of DR5 induced apoptotic cell death in glioma cells without TRAIL and was able to overcome the resistance to TRAIL demonstrated in U373 cells. The Bcl-2 protects cells from DR5 by acting downstream of the receptor, most likely at the level of caspase activation.
Apoptosis↗
Fetal and ovarian radiation dose in patients undergoing gamma knife radiosurgery.
BACKGROUND: It is difficult to estimate the fetal or ovarian radiation dosage for female patients undergoing Gamma Knife radiosurgery. Our goals are to determine the fetal and ovarian radiation dose at various distances from a cranial isocenter, to provide a reference for practitioners to estimate the fetal dose with respect to gestational age, and to identify the components of pelvic extracranial radiation. METHODS: An anthropomorphic phantom and ion chamber were used to measure the dose at 50, 60, and 70 cm from a cranial isocenter and at three points within the transverse plane for the supine position. Each measurement consisted of a 5-minute exposure. Additional measurements were taken for four collimator sizes, the prone position, off-axis, and with one-half of all collimator holes plugged. RESULTS: The values of the fetal and ovarian dose rates ranged from 0.27 cGy/min to 0.05 cGy/min based on distance from the isocenter. The fetal and ovarian dose can be up to 8.1 cGy for a 30-minute Gamma Knife treatment. The dose fell off more rapidly than predicted by the inverse square law. There was no dependence of fetal dose rate on collimator size. No advantage to the prone position could be shown. Leakage and collimator scatter are the main components of extracranial dose 50 to 70 cm from the isocenter. CONCLUSIONS: The fetal and ovarian dose is a function of treatment time and distance from the isocenter. We recommend pregnancy status assessment in women of reproductive age and treatment plan design using large volume shots in order to minimize treatment time.
Brain Neoplasms↗
Influence of gamma knife radiosurgery on the quality of life in patients with brain metastases.
Quality of life (QOL) is an important issue in the treatment of patients with brain metastases. With median survival times often less than 4 months, less invasive treatment options that maximize QOL parameters are essential. In recent years, stereotactic radiosurgery (SRS) has been commonly used as a noninvasive alternative to surgical resection for such patients. This prospective study was undertaken to evaluate QOL in patients undergoing SRS for brain metastases. Between 1999 and 2000, 20 patients with metastatic disease to the brain were evaluated and treated in our Gamma Knife unit. All patients performed the Spitzer QOL survey (10-point scale) both before stereotactic radiosurgery and at each follow-up visit. Primary sites of disease included lung (n = 10), breast (n = 5), melanoma (n = 2), thyroid (n = 1), uterine (n = 1), and kidney (n = 1). Fifteen (75%) had prior whole brain radiotherapy (median dose: 35 Gy). The median age and Karnofsky Performance Status were 58 years and 80, respectively. The median Spitzer score before SRS was 9 (range: 7-10), and the median follow-up time of the patients in this series was 7 months. The median posttreatment Spitzer score at 1 and 3 months after SRS was 9 (range: 5-10) and 8 (range: 4-10), respectively. Crude intracranial tumor control in this cohort of patients was 90%. Extracranial tumor progression was noted in 8 patients (40%), and in these patients, Spitzer scores tended to decrease in value. In those patients who had no evidence of intracranial or extracranial tumor progression, Spitzer scores remained either unchanged or improved. Gamma knife SRS is an appropriate treatment modality for maintaining QOL parameters in patients with brain metastases. Tumor progression both intracranially and extracranially influences QOL parameters. Confirmation of this finding will require further investigation.
Aged↗