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Biomedical subjects

Robert L Foote

Publications and source records attributed to Robert L Foote.

At least 19 recordsLinked to original sources
PubMed2007

Informed consent in advanced laryngeal cancer.

PURPOSE: This study was designed to evaluate the relationship between the informed consent process and the treatment received by patients with advanced laryngeal cancer. METHODS: The study group was composed of 101 consecutive patients who were eligible for the Department of Veterans Affairs Laryngeal Cancer Study Group and Radiation Therapy Oncology Group/Head and Neck Intergroup (RTOG 91-11) larynx preservation clinical trials and who underwent treatment at the Mayo Clinic during the years 1985 to 2000. Records were reviewed to evaluate the effect that referral to an oncologist, discussion and documentation of treatment alternatives by the surgeon, offering a chance at a larynx conservation surgical procedure, and treatment recommendation made by the surgeon have on the treatment chosen and received by the patient. RESULTS: Discussion of treatment alternatives by the surgeon (p = .0054), referral to an oncologist (p < .0001), offering a chance for a larynx conservation surgical procedure (p = .047), and treatment recommended by the surgeon (p < .0001) were significantly related to the treatment received by the patient. CONCLUSION: The treatment received by a patient with advanced laryngeal cancer is determined by the treatment recommended by the surgeon, referral to an oncologist, discussion of treatment alternatives by the surgeon, and offering a chance for a larynx conservation surgical procedure.

Combined Modality Therapy↗
PubMed2006

Long-term results of irradiation for paraganglioma.

PURPOSE: The management of paragangliomas is controversial. Observation, surgery, external-beam radiotherapy (EBRT), and stereotactic radiosurgery (SRS) may, alone or in combination, be appropriate, depending on the size and extent of the tumor, previous treatment, and patient age, general health, and neurologic condition. Few data exist regarding long-term tumor control and late effects after EBRT or SRS. METHODS AND MATERIALS: We performed a retrospective review of all patients treated with EBRT or SRS for paraganglioma at our institution between 1967 and 1994. The endpoints of the study were tumor control and late complications. RESULTS: The 33 patients in this study had a median follow-up of 13 years (range, 4 months to 36 years). The 10-year tumor control rate was 92% (95% confidence interval, 75-98%). At the last follow-up visit, no patient had developed a radiation-induced malignancy. CONCLUSION: External-beam RT and SRS are safe and effective for enlarging and/or symptomatic paragangliomas. The risk of developing a delayed radiation-induced malignancy after EBRT or SRS is low. This risk must be weighed against the significant immediate and permanent risk of cranial nerve deficits if the tumor is untreated or is surgically resected. This risk must also be weighed against the immediate but low risk of surgical mortality.

Adolescent↗
PubMed2006

Organ preservation for advanced laryngeal carcinoma.

BACKGROUND: Inclusion of patients with mobile vocal cords on larynx preservation trials may lead to overstatement of larynx preservation (LPR) and survival (OS) rates. METHODS: This is a retrospective review of patients at our institution who would have been eligible for the Department of Veterans Affairs Laryngeal Cancer Study Group (VA) and Radiation Therapy Oncology Group/Head and Neck Intergroup (RTOG 91-11) clinical trials. No laryngeal conservation procedure could be performed in patients with mobile vocal cords. RESULTS: One hundred one patients at our institution would have been eligible for the VA trial. The 2-year OS was 76% for total laryngectomy and 90% for radiotherapy patients (p = .28) compared with 68% reported for the VA trial. Seventy-three patients at our institution would have been eligible for the RTOG 91-11 trial. The 5-year OS was 52% for total laryngectomy and 63% for radiotherapy patients (p = .18) compared with 55% reported for the RTOG 91-11 trial. Radiotherapy patients had an LPR of 80% (VA trial) and 86% (RTOG 91-11 trial). CONCLUSION: It is unlikely that inclusion of patients with mobile vocal cords had a significant impact on OS or LPR for the VA and RTOG 91-11 larynx preservation trials.

Carcinoma, Squamous Cell↗
PubMed2006

Patient outcomes after vestibular schwannoma management: a prospective comparison of microsurgical resection and stereotactic radiosurgery.

OBJECTIVE: The best management for patients with small- to medium-sized vestibular schwannomas (VS) is controversial. METHODS: : A prospective cohort study of 82 patients with unilateral, unoperated VS less than 3 cm undergoing surgical resection (n = 36) or radiosurgery (n = 46). Patients undergoing resection were younger (48.2 yr versus 53.9 yr, P = 0.03). The groups were similar with regard to hearing loss, associated symptoms, and tumor size. The mean follow-up period was 42 months (range, 12-62 mo). RESULTS: Normal facial movement and preservation of serviceable hearing was more frequent in the radiosurgical group at 3 months (P < 0.001), 1 year (P < 0.001), and at the last follow-up examination (P < 0.01) compared with the surgical resection group. Patients undergoing surgical resection had a significant decline in the following subscales of the Health Status Questionnaire 3 months after surgery: physical functioning (P = 0.006), role-physical (P < 0.001), energy/fatigue (P = 0.02), and overall physical component (P = 0.004). Patients in the surgical resection group continued to have a significant decline in the physical functioning (P = 0.04) and bodily pain (P = 0.04) subscales at 1 year and in bodily pain (P = 0.02) at the last follow-up examination. The radiosurgical group had no decline on any component of the Health Status Questionnaire after the procedure. The radiosurgical group had lower mean Dizziness Handicap Inventory scores (16.5 versus 8.4, P = 0.02) at the last follow-up examination. There was no difference in tumor control (100 versus 96%, P = 0.50). CONCLUSION: Early outcomes were better for VS patients undergoing stereotactic radiosurgery compared with surgical resection (Level 2 evidence). Unless long-term follow-up evaluation shows frequent tumor progression at currently used radiation doses, radiosurgery should be considered the best management strategy for the majority of VS patients.

Cohort Studies↗
PubMed2005

A historical prospective cohort study of carotid artery stenosis after radiotherapy for head and neck malignancies.

PURPOSE: To determine carotid artery stenosis incidence after radiotherapy for head-and-neck neoplasms. METHODS AND MATERIALS: This historical prospective cohort study comprised 44 head-and-neck cancer survivors who received unilateral neck radiotherapy between 1974 and 1999. They underwent bilateral carotid duplex ultrasonography to detect carotid artery stenosis. RESULTS: The incidence of significant carotid stenosis (8 of 44 [18%]) in the irradiated neck was higher than that in the contralateral unirradiated neck (3 of 44 [7%]), although this difference was not statistically significant (p = 0.13). The rate of significant carotid stenosis events increased as the time after radiotherapy increased. The risk of ipsilateral carotid artery stenosis was higher in patients who had undergone a neck dissection vs. those who had not. Patients with significant ipsilateral stenosis also tended to be older than those without significant stenosis. No other patient or treatment variables correlated with risk of carotid artery stenosis. CONCLUSIONS: For long-term survivors after neck dissection and irradiation, especially those who are symptomatic, ultrasonographic carotid artery screening should be considered.

Adult↗
PubMed2005

Gamma knife radiosurgery of radiation-induced intracranial tumors: local control, outcomes, and complications.

PURPOSE: To determine local control (LC) and complication rates for patients who underwent radiosurgery for radiation-induced intracranial tumors. METHODS AND MATERIALS: Review of a prospectively maintained database (2,714 patients) identified 16 patients (20 tumors) with radiation-induced tumors treated with radiosurgery between 1990 and 2004. Tumor types included typical meningioma (n=17), atypical meningioma (n=2), and schwannoma (n=1). Median patient age at radiosurgery was 47.5 years (range, 27-70 years). The median tumor margin dose was 16 Gy (range, 12-20 Gy). Median follow-up was 40.2 months (range, 10.8-146.2 months). Time-to-event outcomes were calculated with Kaplan-Meier estimates. RESULTS: Three-year and 5-year LC rates were 100%. Three-year and 5-year overall survival rates were 92% and 80%, respectively. Cause-specific survival rates at 3 and 5 years were 100%. Three patients died: 1 had in-field progression 65.1 months after radiosurgery and later died of the tumor, 1 died of progression of a preexisting brain malignancy, and 1 died of an unrelated cause. One patient had increased seizure activity that correlated with development of edema seen on neuroimaging. CONCLUSIONS: LC, survival, and complication rates in our series are comparable to those in previous reports of radiosurgery for intracranial meningiomas. Also, LC rates with radiosurgery are at least comparable to those of surgical series for radiation-induced meningiomas. Radiosurgery is a safe and effective treatment option for radiation-induced intracranial tumors, most of which are typical meningiomas.

Adult↗
PubMed2005

Evaluation of tumor angiogenesis measured with microvessel density (MVD) as a prognostic indicator in nasopharyngeal carcinoma: results of RTOG 9505.

PURPOSE: The objective of this study was to evaluate tumor angiogenesis as measured by microvessel density (MVD) as an independent prognostic factor in patients with nasopharyngeal carcinoma (NPC) treated with radiotherapy alone. METHODS AND MATERIALS: Eligible patients included those with NPC treated with radiotherapy. Paraffin blocks of the primary tumor had a hematoxylin and eosin-stained section prepared at the block face. One representative section for tumor was stained for factor VIII-related antigen using a standard immunoperoxidase staining technique. MVD was determined by light microscopy in areas of invasive tumor containing the highest numbers of capillaries and microvessels per area. Individual microvessel counts were made on a 200x field within the area of most intense tumor neovascularization. Results were expressed as the highest number of microvessels identified within any single 200x field. Using a breakpoint of MVD <60 vs. > or =60, the distributions between the two MVD groups were compared by the method of Gray. Overall survival rates were estimated by the Kaplan-Meier method and compared by the log-rank test. A multivariate Cox proportional hazard model was employed to examine the relationship between MVD and disease outcomes while adjusting for other concomitant variables. RESULTS: One hundred sixty-six were eligible, of whom 123 had values determined for MVD. The MVD values ranged from 9 to 243 with a median of 70. In the multivariate analysis of overall survival, distant metastases, and local-regional failure, MVD did not significantly improve the model containing T stage, N stage, age, radiation dose, and World Health Organization class. CONCLUSIONS: We found no significant differences in overall survival, time to distant metastasis, or time to local-regional failure using a breakpoint of MVD <60 vs. MVD > or =60. The study was perhaps limited by the small size of the NPC samples.

Adolescent↗
PubMed2005

A pilot study of high-dose intraarterial cisplatin chemotherapy with concomitant accelerated radiotherapy for patients with previously untreated T4 and selected patients with T3N0-N3M0 squamous cell carcinoma of the upper aerodigestive tract.

BACKGROUND: This Phase I clinical trial was developed to assess the feasibility of combining high-dose intraarterial cisplatin chemotherapy with concurrent, concomitant boost accelerated radiation therapy for patients with previously untreated T4 and select patients with T3N0-N3M0 squamous cell carcinoma of the upper aerodigestive tract. METHODS: Between July 1999, and February 2002, 19 patients were treated with 3 or 4 weekly cycles of intraarterial Cisplatin chemotherapy (150 mg/m(2)) with concurrent, concomitant boost accelerated radiation therapy (72 grays in 42 fractions over 6 weeks). RESULTS: Two patient deaths occurred among the first 15 patients enrolled. Both patients presented with febrile neutropenia, and both died of complications related to infection. The number of cycles of intraarterial cisplatin was reduced from four cycles to three cycles, and an additional four patients were treated. The fourth patient treated on the modified protocol developed febrile neutropenia, sepsis, and a thromboembolic event, which resulted in lower extremity amputations. The maximum acute toxicity experienced was Grade 2 in 6 patients, Grade 3 in 5 patients, Grade 4 in 6 patients, and Grade 5 in 2 patients. With a median follow-up of 21 months (range, 6.2-34.6 months), the overall survival at 1 year was 89.5% (95% confidence interval [95%CI], 76.7-100%). At 1 year, 92.9% of the patients were free from disease progression (95%CI, 80.3-100%). CONCLUSIONS: The results of this study suggest that concurrent intraarterial cisplatin chemotherapy at a dose of 150 mg/m(2) with concomitant boost accelerated radiation therapy is not feasible.

Adult↗
PubMed2005

A buccal mucosa carcinoma treated with high dose rate brachytherapy.

This manuscript presents a case of early stage squamous cell carcinoma of the left buccal mucosa treated with intensity-modulated radiation therapy (IMRT) followed by a high-dose rate (HDR) brachytherapy boost. With limited literature available on HDR mold (stent) radiotherapy for oral cancer, a discussion on the issues encountered during treatment planning and delivery may prove to be insightful for facilities faced with a similar challenge.

Brachytherapy↗
PubMed2005

Repeat radiosurgery for idiopathic trigeminal neuralgia.

PURPOSE: Although frequently performed, the efficacy and safety of repeat trigeminal neuralgia radiosurgery is not well described. METHODS AND MATERIALS: Between August 1997 and December 2002, 19 patients (9 men, 10 women) underwent repeat trigeminal neuralgia radiosurgery. The median interval between procedures was 16 months. The median dose (based on an output factor of 0.87 for the 4-mm collimator) for repeat radiosurgery was 76.1 Gy; the median additive dose was 163.1 Gy. Outcomes were defined as excellent (no pain, no medications), good (no pain, reduced medications), fair (>50% pain reduction), and poor. Median follow-up was 24 months. RESULTS: Outcomes after repeat radiosurgery were excellent (n = 14, 74%), good (n = 1, 5%), fair (n = 3, 16%), and poor (n = 1, 5%). Two patients had recurrent pain at 7 and 22 months; 71% and 61% of patients had an excellent outcome at 1- and 2-years after radiosurgery, respectively. Eleven patients (58%) described facial parathesias (n = 3), numbness (n = 5) or dyesthesias (n = 3). Two patients (11%) developed corneal numbness. Nine of 11 patients (82%) with new trigeminal deficits had excellent outcomes at last follow-up compared with 3 of 8 patients (38%) with unchanged facial sensation (p = 0.07). CONCLUSIONS: Repeat trigeminal neuralgia radiosurgery at the dosage described has better facial pain outcomes than primary radiosurgery. However, because the procedure is nonselective and the rate of bothersome numbness was relatively high (16%), dose reduction is recommended to reduce the morbidity of repeat trigeminal neuralgia radiosurgery.

Adult↗
PubMed2005

Radiosurgery for cranial base chordomas and chondrosarcomas.

OBJECTIVE: To evaluate the efficacy and toxicity of radiosurgery in the treatment of cranial base chordoma and chondrosarcoma. METHODS: We reviewed 29 patients with cranial base chordoma (n = 25) or chondrosarcoma (n = 4) who underwent stereotactic radiosurgery between September 1990 and December 2002. The median patient age was 45 years (range, 10-81 yr). Nineteen patients also had radiation therapy before or in conjunction with radiosurgery (median dose, 50.4 Gy). The median tumor volume was 14.4 cm3 (range, 0.6-65.1 cm3). The median tumor margin dose was 15 Gy (range, 10-20 Gy); the median maximum radiation dose was 30 Gy (range, 20-40 Gy). Median clinical and imaging follow-up periods were 4.8 and 4.5 years, respectively. RESULTS: Seven chordoma patients (28%) had tumor progression (in-field, n = 3; out-of-field, n = 4), whereas 18 had stable disease or tumor shrinkage. No patient with a chondroid chordoma had tumor enlargement. The actuarial tumor control rates were 89 and 32% at 2 and 5 years, respectively. All 4 patients with chondrosarcoma had tumor control. Clinically, 7 patients (24%) had improvement of pretreatment symptoms, 16 (55%) remained stable, and 6 (21%) worsened. Three patients with tumor progression died. Ten patients (34%) had radiation-related complications. Complications included cranial nerve deficits (n = 6), radiation necrosis (n = 5), and pituitary dysfunction (n = 3). Patients having radiosurgery alone had no toxicity. CONCLUSION: Cranial base chordomas and chondrosarcomas remain a formidable management challenge. Radiosurgery as an adjunct to surgical resection provides in-field tumor control for some patients, but radiation-related complications are relatively high, especially when radiosurgery is combined with fractionated radiation therapy.

Chondrosarcoma↗
PubMed2004

Donepezil and vitamin E for preventing cognitive dysfunction in small cell lung cancer patients: preliminary results and suggestions for future study designs.

BACKGROUND: Up to 90% of small cell lung cancer (SCLC) patients suffer cognitive dysfunction. Since donepezil and vitamin E have been somewhat successful in treating other dementias, this study tested the hypothesis that these agents can prevent cognitive decline in SCLC patients. Because accrual was poor, this trial also offered opportunities for suggesting other study designs for future clinical trials on cognitive dysfunction in this group of patients. METHODS: This double blind, placebo controlled trial tested oral donepezil 5 mg/day (with dose escalation to 10 mg after 1 month) and oral vitamin E 1,000 IU/day in SCLC patients after completion of all cancer therapy, including prophylactic cranial irradiation (PCI). Cognition, adverse events, and quality of life were assessed throughout the study period. RESULTS: Only nine of 104 patients enrolled over 15 months (four donepezil and vitamin E-treated versus five placebo-exposed), and thus no definitive conclusions could be drawn. Nonetheless, the only patient who manifested a precipitous decline in cognition was taking donepezil and vitamin E. There was also a slight trend of increased gastrointestinal side effects among donepezil and vitamin E-treated patients. There were no notable differences in cognitive stability, adverse events, or quality of life between treatment arms. CONCLUSION: These preliminary findings do not provide enthusiasm for testing donepezil and vitamin E in the manner undertaken here for preventing cognitive dysfunction in SCLC patients. Eligibility criteria and timing of trial intervention are discussed as potential impediments to successful trial completion.

Aged↗
PubMed2004

Tobacco use outcomes among patients with head and neck carcinoma treated for nicotine dependence: a matched-pair analysis.

BACKGROUND: The current study described tobacco use outcomes among patients with head and neck carcinoma who underwent treatment for nicotine dependence at the Mayo Clinic Nicotine Dependence Center (NDC; Rochester, MN). METHODS: Using a 1:1 matched-pair design, conditional logistic regression was employed to compare the 6-month tobacco abstinence outcomes of patients with head and neck carcinoma (n = 101) with controls (n = 101) from the general patient population treated for nicotine dependence between 1988 and 2001. The two groups were matched with regard to age, gender, date of treatment, and type of NDC treatment service. RESULTS: Baseline demographics were similar between both groups. However, patients with head and neck carcinoma smoked significantly more cigarettes per day (cpd) than controls (P = 0.003). The self-reported tobacco abstinence rate at the 6-month follow-up was 33% for patients with head and neck carcinoma compared with 26% for matched controls (P = 0.279; after adjusting for baseline cpd and stage of change, P = 0.205). Among patients with head and neck carcinoma, the tobacco abstinence rates were 47%, 22%, and 19%, respectively, for those receiving an NDC consult within 3 months, between 3 months and 5 years, and > 5 years after their diagnosis (P = 0.021). Furthermore, the patients with head and neck carcinoma treated within 3 months of diagnosis who received surgery (with or without radiation therapy) were more likely to be tobacco abstinent than those who received primary radiation therapy (P = 0.042). CONCLUSIONS: These findings suggested that nicotine dependence treatments were effective among patients with head and neck carcinoma, particularly when delivered shortly after initial diagnosis and for those who received surgery as their primary treatment.

Head and Neck Neoplasms↗
PubMed2004

Radiosurgery as primary management for meningiomas extending into the internal auditory canal.

Stereotactic radiosurgery is increasingly utilized as primary management for patients with skull base meningiomas. This study reviews the results of stereotactic radiosurgery for patients with meningiomas extending into the internal auditory canal (IAC) to determine the risk of facial weakness or hearing loss. From 1990 to 2002, 16 patients had radiosurgery for meningiomas extending into the IAC. The median patient age was 63 years. Ten patients had symptoms of vestibulocochlear nerve dysfunction before radiosurgery. The median tumor volume was 5.1 cm3; the median tumor extension into the IAC was 7 mm (range, 3-12). The median tumor margin dose was 15 Gy. The median follow-up was 36 months. Ten meningiomas (63%) decreased in size, and 6 tumors were unchanged. No patient developed facial weakness. One patient (6%) had worsened facial sensation. Three of 14 patients (21%) with either normal hearing clinically (n = 5) or documented Gardner-Robertson class 1-2 before radiosurgery (n = 9) had decreased hearing after radiosurgery. The 1-, 2- and 5-year actuarial incidences of hearing preservation were 93, 84 and 42%, respectively. Three patients (19%) had improved hearing after radiosurgery. One patient with class 2 hearing improved to class 1; 2 patients with no speech discrimination before radiosurgery (class 5) improved to a class 3 status following the procedure. The risk of facial weakness or hearing loss is low after radiosurgery for patients with meningiomas extending into the IAC. Radiosurgery is an excellent alternative to surgical excision for meningiomas in this location, especially if a subtotal resection is likely or a hearing-sacrificing operation such as a translabyrinthine approach is contemplated.

Aged↗
PubMed2004

Chemotherapy in the management of advanced cutaneous squamous cell carcinoma in organ transplant recipients: theoretical and practical considerations.

BACKGROUND: The use of chemotherapy in organ transplant recipients (OTRs) with advanced and metastatic cutaneous squamous cell carcinoma (SCC) remains relatively unexplored in dermatology. Advances in the use of chemotherapy in metastatic head and neck squamous cell carcinoma (HNSCC) may be applicable to this increasingly common disease. OBJECTIVE: The objective of this study was to determine whether recent advances in the role of chemotherapy in the management of HNSCC and cutaneous SCC offer insights into treatment strategies for metastatic cutaneous SCC. METHODS: We reviewed the literature pertaining to treatment of advanced and metastatic HNSCC and cutaneous SCC, with particular attention to the role of chemotherapy. In addition, specialists in the fields of cutaneous oncology and dermatologic surgery, head and neck surgery, medical oncology, and radiation oncology were consulted for expert multidisciplinary advice. RESULTS: Specific roles for chemotherapy in the management of advanced and cutaneous HNSCC are discussed and summarized. In addition, we propose theoretical analogies in the treatment of advanced and metastatic cutaneous SCC in OTRs. CONCLUSIONS: The head and neck surgery and oncology literature is rich with experience in locoregionally advanced and metastatic HNSCC, and adaptation of management concepts may prove feasible in the management of OTRs with advanced and metastatic cutaneous SCC.

Antineoplastic Agents↗
PubMed2004

A methodology to determine margins by EPID measurements of patient setup variation and motion as applied to immobilization devices.

Assessment of clinic and site specific margins are essential for the effective use of three-dimensional and intensity modulated radiation therapy. An electronic portal imaging device (EPID) based methodology is introduced which allows individual and population based CTV-to-PTV margins to be determined and compared with traditional margins prescribed during treatment. This method was applied to a patient cohort receiving external beam head and neck radiotherapy under an IRB approved protocol. Although the full study involved the use of an EPID-based method to assess the impact of (1) simulation technique, (2) immobilization, and (3) surgical intervention on inter- and intrafraction variations of individual and population-based CTV-to-PTV margins, the focus of the paper is on the technique. As an illustration, the methodology is utilized to examine the influence of two immobilization devices, the UON thermoplastic mask and the Type-S head/ neck shoulder immobilization system on margins. Daily through port images were acquired for selected fields for each patient with an EPID. To analyze these images, simulation films or digitally reconstructed radiographs (DRR's) were imported into the EPID software. Up to five anatomical landmarks were identified and outlined by the clinician and up to three of these structures were matched for each reference image. Once the individual based errors were quantified, the patient results were grouped into populations by matched anatomical structures and immobilization device. The variation within the subgroup was quantified by calculating the systematic and random errors (sigma(sub) and sigma(sub)). Individual patient margins were approximated as 1.65 times the individual-based random error and ranged from 1.1 to 6.3 mm (A-P) and 1.1 to 12.3 mm (S-I) for fields matched on skull and cervical structures, and 1.7 to 10.2 mm (L-R) and 2.0 to 13.8 mm (S-I) for supraclavicular fields. Population-based margins ranging from 5.1 to 6.6 mm (A-P) and 3.7 to 5.7 mm (S-I) were calculated for the corresponding skull/cervical field and 9.3 to 10.0 mm (L-R) and 6.3 to 6.6 mm (S-I) for the supraclavicular fields, respectively. The reported CTV-to-PTV margins are comparable to a value 7-15 mm based on traditional Mayo margins, but in some cases exceed the default values established in RTOG Head and Neck studies. The data suggests that the population-based margins provide sufficient coverage for the majority of the patients. However, the population-derived margins are excessive for some patients and insufficient for others, suggesting that a re-evaluation of current treatment margins for individual patients is warranted. Finally, this methodology provides direct evidence of treatment variation and thus can demonstrate with confidence, the superiority of one technique over another.

Algorithms↗
PubMed2004

Leksell Gamma Knife coordinate setting slippage: how often, how much?

OBJECT: The aim of this study was to determine the incidence and magnitude of coordinate setting slippage during gamma knife surgery (GKS). METHODS: Thirty-six consecutive patients undergoing GKS with a Leksell unit between June and December 2000 had their coordinates (right and left x-, y-, and z-coordinates; 1548 coordinates; 258 isocenters) and gamma angles checked after the delivery of treatment to each isocenter to determine whether the coordinate settings had slipped and, if so, which settings and the magnitude of the slippage. CONCLUSIONS: Coordinate setting slippage during GKS with a Leksell unit does occur but is rare. The magnitude of such slippage is typically within the error of the stereotactic system and coordinate reading. The authors noted that coordinate setting slippage is significantly correlated with patient weight.

Adolescent↗