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Results for “Targeted dosing”

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At least 343 records · Page 19Linked to original sources

PubMed2000

High dose therapy and autologous stem cell transplantation for human immunodeficiency virus-associated non-Hodgkin lymphoma in the era of highly active antiretroviral therapy.

BACKGROUND: The advent of highly active antiretroviral therapy (HAART) has allowed the exploration of more dose-intensive therapy such as autologous stem cell transplantation (ASCT) in selected patients with human immunodeficiency virus (HIV)-associated non-Hodgkin lymphoma (NHL). METHODS: The authors report on the use of myeloablative chemotherapy with ASCT in two HIV positive patients with NHL. The first patient underwent ASCT at the time of first disease remission for poor risk, diffuse, large cell NHL and the second patient had multiply recurrent, chemosensitive Burkitt lymphoma. ASCT was performed in both patients using a transplant conditioning regimen of high dose cyclophosphamide, carmustine, and etoposide (CBV). RESULTS: The target dose of >/= 5 x 10(6)/kg CD34 positive peripheral blood stem cells (PBSC) utilized for ASCT was collected using granulocyte-colony stimulating factor (G-CSF) after chemotherapy for mobilization while both patients were receiving concomitant HAART for HIV infection. HAART was continued during CBV conditioning. Prompt hematopoietic recovery was observed after ASCT. Both patients remained in clinical disease remission from their lymphoma at 28 months and 20 months after transplant, respectively. CONCLUSIONS: ASCT is feasible in patients with HIV-associated NHL. Adequate numbers of CD34 positive PBSC can be procured from patients receiving HAART and chemotherapy for NHL. Selected patients with HIV-related lymphoma can tolerate the high dose CBV myeloablative chemotherapy regimen without increased acute regimen-related toxicity. Reinfusion of G-CSF-mobilized PBSC can lead to rapid recovery of hematologic function and sustained engraftment after ASCT. Given the poor prognosis of patients with HIV-associated NHL treated with conventional chemotherapy, further investigation of this approach should be considered.

Adult↗

PubMed1996

The effects of prostaglandin E1 on hepatic allograft vascular inflow: a prospective randomized double-blind study.

Improved hepatic microcirculation is one of the postulated mechanisms by which prostaglandin E1 (PGE(1)) could improve liver function in the setting of fulminant hepatic failure or poor allograft function immediately post-transplant. The purpose of this study was to determine whether PGE(1) improves hepatic allograft arterial and portal vein inflow. Fifty patients receiving a primary liver transplant were entered into a prospective randomized double-blind study. Measurements of hepatic arterial and portal venous flow were taken immediately after revascularization and after steady state drug infusion. PGE(1) (or placebo) was infused peripherally at an increasing dose and titrated for blood pressure to a target dose of 1 microgram/kg/hr (80 microgram/hr maximum). Changes in hepatic arterial and portal vein flow, and time to reach maximum dose were compared using the student's t test. Of the 50 patients entered, 15 were excluded from analysis (10 because of inability to obtain flow measurements, 4 because they were pediatric recipients <2 yrs of age, and 1 patient who was placed on open PGE(1)). Thirty-five patients were available for final analysis (control, N = 14; PGE(1),N = 21). There were no statistical differences in the change in hepatic artery of portal vein flow between PGE(1)-treated and -untreated grafts. The time to reach maximum dose of PGE(1) was longer in the PGE(1) treatment group. Maximum dose was reached in 85.7 per cent of patients in both groups. There was an effect on blood pressure in the study group as demonstrated by a longer time to reach maximum dose. There was no effect on hepatic vascular in flow.

Adult↗

PubMedDate not supplied

[Stereotactic radiosurgery with linear accelerator (LINAC). Report of the technical experience in 100 cases treated at the Mexico General Hospital].

UNLABELLED: Stereotactic radiosurgery consists of the release and high dose radiation inside the intracraneal, small, well defined and stereotactic localized injury. OBJECTIVE: In this study we describe the technical aspects, clinical results and dose radiation levels used in 100 patients treated with LINAC. METHODS: One hundred patients received treatment with LINAC stereotactic radiosurgery, 34 AVM, 22 meningiomas, 18 astrocytomas, 11 pituitary adenomas, 5 cavernous malformations, 3 acoustic neuromas, 3 craniopharyngiomas, 2 cases of epilepsy, one brain metastasis and one ependymoma. The radiation dose changed in each case. Studied variables: response of the injury, toxicity, in target dose, number of isocenters, number of treatment arcs, number o fcollimators, dose of risk organ, homogeneity of target, margin of error, target, diameter of collimator and location of target. We applied the chi2 test with statistical significance of p < 0.05. RESULTS: The median follow-up was 17.7 months. We had 3 cases of minor toxicity. We confirmed that for a greater target volume, greater number of treatment arcs were necessary, with greater margins of errors and greater number of isocenters. CONCLUSIONS: Radiosurgery is a safe and reliable technique to treat benign and malignant intracraneal lesions.

Adolescent↗

PubMed2004

A phase I and pharmacologic study of the MDR converter GF120918 in combination with doxorubicin in patients with advanced solid tumors.

BACKGROUND: Resistance to chemotherapy can partly be explained by the activity of membrane bound P-glycoprotein. Competitive inhibition of P-glycoprotein, by multidrug resistance (MDR) converters, may overcome this MDR. Previously studied MDR converters either have serious intrinsic side effects or considerably influence the pharmacokinetics of cytotoxic agents at concentrations theoretically required to convert MDR. GF120918 is a third-generation MDR converter with high affinity for P-glycoprotein and can be given orally. We performed a phase 1 study with escalating doses of GF120918 in combination with doxorubicin. PATIENTS AND METHODS: The study group comprised 46 patients with advanced solid tumors. Doxorubicin was administered on day 1 (cycle 1), GF120918 on days 22-24 (cycle 2), and on days 29-33 with doxorubicin administered on day 31 (cycle 3). Pharmacokinetics of both GF120918 and doxorubicin were studied. The starting daily dose of GF120918 was 50 mg and was to be increased in subsequent cohorts until a steady state plasma level of 100 ng/ml was reached. The starting dose of doxorubicin was 50 mg/m2 and was to be increased after reaching the target dose level of GF120918. RESULTS: In 37 of the 46 patients, full pharmacokinetic data from the three scheduled cycles were obtained. Pharmacokinetics of GF120918 showed a less than linear increase in Cmax with increasing doses, with considerable interpatient variation. The target steady-state plasma level for GF120918 was exceeded in 12 out of 19 patients who received 400 mg GF120918 alone twice daily and in 12 of 17 patients who received 400 mg GF120918 twice daily in combination with doxorubicin. GF120918 pharmacokinetics were not influenced by coadministration of doxorubicin. The doxorubicin AUC was only marginally influenced by GF120918 and only at the highest dose levels. In these patients there was a significant increase in the AUC of doxorubicinol in cycle 3 as compared to cycle 1. Hematologic toxicity mainly consisted of neutropenia and was more severe in cycle 3 than in cycle 1 (13 vs 5 patients with grade 4 neutropenia, P=0.003). Neutropenic fever was the dose-limiting toxicity at a doxorubicin dose of 75 mg/m2 with 400 mg GF120918 twice daily. The toxicity of GF120918 was limited to somnolence in eight patients and occasional gastrointestinal complaints. CONCLUSION: GF120918 is an MDR converter with only minimal side effects at a dose level yielding concentrations able to convert the action of P-glycoprotein in vitro. A doxorubicin dose of 60 mg/m2 on day 3 in combination with 400 mg GF120918 twice daily on days 1-5 is an acceptable regimen for further clinical trials.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

Monte Carlo verification of IMRT dose distributions from a commercial treatment planning optimization system.

The purpose of this work was to use Monte Carlo simulations to verify the accuracy of the dose distributions from a commercial treatment planning optimization system (Corvus, Nomos Corp., Sewickley, PA) for intensity-modulated radiotherapy (IMRT). A Monte Carlo treatment planning system has been implemented clinically to improve and verify the accuracy of radiotherapy dose calculations. Further modifications to the system were made to compute the dose in a patient for multiple fixed-gantry IMRT fields. The dose distributions in the experimental phantoms and in the patients were calculated and used to verify the optimized treatment plans generated by the Corvus system. The Monte Carlo calculated IMRT dose distributions agreed with the measurements to within 2% of the maximum dose for all the beam energies and field sizes for both the homogeneous and heterogeneous phantoms. The dose distributions predicted by the Corvus system, which employs a finite-size pencil beam (FSPB) algorithm, agreed with the Monte Carlo simulations and measurements to within 4% in a cylindrical water phantom with various hypothetical target shapes. Discrepancies of more than 5% (relative to the prescribed target dose) in the target region and over 20% in the critical structures were found in some IMRT patient calculations. The FSPB algorithm as implemented in the Corvus system is adequate for homogeneous phantoms (such as prostate) but may result in significant under or over-estimation of the dose in some cases involving heterogeneities such as the air-tissue, lung-tissue and tissue-bone interfaces.

Computer Simulation↗

PubMed2002

Repeat radiosurgery for refractory trigeminal neuralgia.

OBJECTIVE: Stereotactic radiosurgery has become an important and minimally invasive alternative for patients with refractory trigeminal neuralgia. When a second procedure is necessary, the outcomes are unknown. The degree of pain relief and morbidity after repeat radiosurgery were studied. METHODS: Thirty-one patients underwent a second gamma knife radiosurgery procedure because of unsatisfactory or unsustained relief of pain after the first procedure. Twenty-seven patients were assessable at median follow-up periods of 42.7 and 20.4 months after the first and second procedures, respectively. Most patients had undergone multiple previous operations of other types (microvascular decompression, radiofrequency rhizotomy, glycerol rhizotomy, balloon compression). The median target doses of the first and second radiosurgeries were 75 and 64 Gy, respectively. All patients were evaluated by a physician who did not participate in patient treatment. RESULTS: After the first radiosurgical procedure, 13 patients had an excellent response initially (complete relief without any medication), 3 had a good response (complete relief with some medication), 7 had a fair response (>50% relief), and 4 had a poor response (<50% pain relief or treatment failure). Repeat radiosurgery was performed in patients with recurrent or residual pain. After the second radiosurgical procedure, 5 patients had an excellent response, 8 had a good response, 10 had a fair response, and 4 had a poor response. Thirteen patients (48%) achieved complete pain relief (with or without medication). Two patients (7.4%) experienced new sensory symptoms after the first radiosurgical procedure, and three (12.7%, actuarial) experienced new sensory symptoms after the second procedure. CONCLUSION: Repeat radiosurgery provided a similar rate of pain relief as the first procedure, despite a modest dose reduction. The risk of new sensory symptoms was increased, but no other morbidity was identified. For patients who experience recurrent pain and choose to undergo a second procedure, our current procedure is to deliver a maximum dose of 50 to 60 Gy to a trigeminal target anterior to the root entry zone near the entrance of the nerve beneath the petrous dura.

Adult↗

PubMed1999

Comparison of kilovoltage x-ray and electron beam dose distributions for radiotherapy of the sternum.

The dose distributions for a patient with cancer involving the sternum were calculated for both a kilovoltage x-ray beam and a megavoltage electron beam. The minimum target dose and dose uniformity over the target volume were significantly better using electrons (90%-101%) than kilovoltage x-rays (68%-119%). The calculated lung dose and integral patient dose were also less for electrons than kilovoltage x-rays. For treating cancers of the sternum with radical intent, megavoltage electrons are recommended as the treatment mode of choice rather than kilovoltage x-rays.

Breast Neoplasms↗

PubMed1996

[Experimental radiosurgery in rats using gamma a "gamma knife". Description of a stereotactic device for small laboratory animals].

To allow the experimental use in rats of a Gamma Knife Radiosurgical Unit, a stereotactic device adapted from the conventional Kopf's device was developed. To control the accuracy of the coordinate system based on the De Groot's rat stereotactic atlas, experimental radiosurgical lesions were made on the left striatum. The isodose curve distribution of the 4 mm collimator was calculated with the dose planning software used in Gamma Knife and superimposed on the left striatum target. Doses of 200 Gy were administered to the left striatum in six rats. The results were evaluated 21, 34 and 47 days later. At 34 and 47 days necrotic lesions were exactly as targeted. In a second group of 48 rats receiving a doses of 100 Gy, no lesions were observed after 7, 15, 24, 31, 45 days. However, in all rats sacrificed 59, 72 and 90 days after day radiation, a necrotic lesion was always present and confirmed that at each time the lesions were precisely targeted. This apparatus allows precise and reproducible gamma irradiation lesion in rat brain without expensive and time consuming imaging techniques. This device provides a useful system to observe the experimental effects of radiosurgery on the central nervous system in rats.

Animals↗

PubMed2001

Paroxetine for social anxiety and alcohol use in dual-diagnosed patients.

The objective of this study was to compare the efficacy and tolerability of paroxetine to matched placebo in adults with co-occurring social anxiety disorder and alcohol use disorder. Outcome measures included standardized indices of social anxiety and alcohol use. Fifteen individuals meeting DSM-IV criteria for both social anxiety disorder and alcohol use disorder were randomized to treatment. Paroxetine (n = 6) or placebo (n = 9) was given in a double-blind format for 8 weeks using a flexible dosing schedule. Dosing began at 20 mg/d and increased to a target dose of 60 mg/d. There was a significant effect of treatment group on social anxiety symptoms, where patients treated with paroxetine improved more than those treated with placebo on both the Clinical Global Index (CGI) and the Liebowitz Social Anxiety Scale (Ps < or = 0.05). On alcohol use, there was not a significant effect of treatment on quantity/frequency measures of drinking, but there was for the CGI ratings (50% paroxetine patients versus 11% placebo patients were improvers on drinking, P < or = 0.05). This pilot study suggests that paroxetine is an effective treatment for social anxiety disorder in individuals with comorbid alcohol problems, and positive treatment effects can be seen in as little as 8 weeks. Further study is warranted to investigate its utility in helping affected individuals reduce alcohol use.

Adolescent↗

PubMed2007

Duloxetine for the treatment of major depressive disorder: safety and tolerability associated with dose escalation.

Duloxetine has demonstrated efficacy for the treatment of major depressive disorder (MDD) at a dose of 60 mg/day (given once daily). Whereas the target dose for the majority of patients is 60 mg/day, higher duloxetine doses (up to 120 mg/day) have been studied using a twice-daily dosing schedule. To further investigate the pharmacological profile of duloxetine within a once-daily dosing regimen at doses above 60 mg, we examined the safety and tolerability of duloxetine during a dose escalation from 60 mg/day to 120 mg/day. This single-arm, non-placebo-controlled study incorporated a 7-week dose escalation phase, in which patients and investigators were blinded as to timing of dose increases, followed by an open-label extension phase of up to 2 years duration. Patients (age >or=18 years) meeting DSM-IV criteria for MDD (n=128) received placebo for 1 week, followed by duloxetine (60 mg/day) titrated after 1 week to 90 mg/day, and after a further week to 120 mg/day. The dose of 120 mg/day was then maintained for 4 weeks. The extension phase comprised an initial 6-week dose stabilization period, during which duloxetine was tapered to the lowest effective dose, followed by continuation therapy at the stabilized dose. We assessed safety using spontaneously reported treatment-emergent adverse events (TEAEs), changes in vital signs, electrocardiograms (ECGs), laboratory analytes, and visual analogue scales (VAS) for gastrointestinal (GI) disturbance. Efficacy measures included the 17-item Hamilton Rating Scale for Depression (HAM-D-17) total score, the Clinical Global Impression of Severity (CGI-S) and Patient Global Impression of Improvement (PGI-I) scales, and VAS assessments of pain severity and interference. The rate of discontinuation due to adverse events during the acute phase of the study was 15.6%. The most frequently reported TEAEs were nausea, headache, dry mouth, dizziness, and decreased appetite. The majority of TEAEs were associated with initial duloxetine dosing; further escalations in dose produced few additional adverse events. VAS measures of GI disturbance worsened significantly compared with baseline values after 1 week of duloxetine treatment. Subsequent assessments of GI disturbance, following dose escalation to 90 mg/day and 120 mg/day, showed either no significant difference or a significant improvement from baseline. Significant improvements (P<.001) were observed in all assessed depression efficacy measures, and in five of six VAS pain outcomes, during acute phase treatment. During 2 years of extension phase therapy, the rate of discontinuation due to adverse events was 11.9%, and the only TEAEs reported by >10% of patients were upper respiratory tract infection (13.1%), headache (10.7%), and insomnia (10.7%). Mean changes from baseline to the end of the extension phase in supine systolic and diastolic blood pressure were 3.8 and 0.5 mm Hg, respectively, and there were no reports of sustained hypertension. Mean increase in heart rate was 5.9 bpm, while patients exhibited a mean weight increase of 3.1 kg over 2 years of treatment. Results from this study suggest that rapid dose escalation of duloxetine (60 mg/day --> 90 mg/day --> 120 mg/day) is safe and tolerable. Despite weekly escalation, the majority of adverse events were mild and transient and occurred in the first week of duloxetine dosing (at 60 mg once daily). Long-term treatment at a stabilized duloxetine dose was associated with a relatively low incidence of TEAEs and treatment discontinuation due to adverse events. Time course profiles of body weight and heart rate showed modest increases during 2 years of treatment [ClinicalTrials.gov number, NC T000 42575].

Adult↗

PubMed1991

Improved dose homogeneity in the breast using tissue compensators.

The improvements achievable by introducing individual tissue compensators in photon therapy of the breast were assessed. In 37 patients the dose ranged from +15% to -10% of the mid target dose using combinations of wedge filters and beam weights alone. With a tissue compensator the dose ranged from +4% to -11% provided that allowance was made for lung attenuation. A megavoltage imaging system is a potential source of the X-ray transmission data which can provide a basis for the calculation of thickness of the compensator.

Breast Neoplasms↗

PubMed2004

Clinical effectiveness in adults with chronic schizophrenia.

Schizophrenia is a severe, debilitating mental illness characterised by a progressive decline of the patient's functioning and relationship with the outside world. Although some patients recover, the illness more usually follows a chronic relapsing course. The long-standing nature of the illness gives rise to a variety of issues, such as poor general health and non-adherence to treatment, which can have a significant impact on the clinical effectiveness of antipsychotic therapy. It is therefore important that clinicians consider the wider aspects of clinical effectiveness, such as functional recovery, individual well-being, treatment adherence and patient satisfaction, when assessing the clinical effectiveness of antipsychotic therapy. Of the atypical antipsychotics currently available to treat chronic schizophrenia, clinical experience and results from clinical trials suggest that quetiapine can provide a broad range of symptomatic relief with minimal clinically significant adverse events. This, in turn, may lead to greater patient satisfaction, increased adherence and an improved treatment outcome. As with all atypical antipsychotics, the key to clinical effectiveness is appropriate dosing. Data from recent studies suggest that an appropriate target dose for quetiapine for many adults with schizophrenia is 600 mg/day.

Antipsychotic Agents↗

PubMed1987

The value of the NSD formula in equation of acute and late radiation complications in normal tissue following 2 and 5 fractions per week in breast cancer patients treated with postmastectomy irradiation.

In 1978-1980, inclusive, all breast cancer patients referred for postmastectomy irradiation were treated by 2 fractions per week (73 patients) but due to a high incidence of late complications this fractionation schedule was changed from early 1981 to 5 fractions per week (66 patients) with dose adjustment according to the nominal standard dose (NSD) concept. The dose aim in both regimens was 1345 ret minimum target dose. This allowed a comparison of acute and late complications in the two patient groups treated to the same NSD value, but with different fractionation. The patients have been analysed with respect to acute and late reaction in the skin, subcutaneous tissue, lung and bone, as well as related complications, such as arm oedema and impairment of shoulder movement. Except for the acute skin reactions, all other endpoints could not be adequately predicted by the NSD formula. Thus, telangiectasia greater than or equal to grade 1 and skin fibrosis greater than or equal to grade 2 were found to be 75% and 67% in patients treated with the 2-fraction scheme versus 39% and 5% in patients treated with the 5-fraction scheme. In the 2-fraction regimen, a higher frequency of impairment of shoulder movement and arm oedema was found compared to the 5-fraction regimen, 38% versus 11% and 44% versus 33%, respectively. The acute lung reaction as well as late lung reaction were significantly more pronounced in the 2-fraction regimen than in the 5-fraction regimen (pneumonitis greater than or equal to grade 2, 43% versus 23%, and lung fibrosis greater than or equal to grade 2, 32% versus 17%, in the photon fields, respectively). Further, radiation-induced osteonecrosis in the ribs was significantly more frequent in patients treated with large dose per fraction (19% versus 2%). The data clearly demonstrates the danger by using the NSD formula in equation of two different fractionation schedules. This formula as well as other mathematical models can only be used with caution within the limitations defined by the underlying clinical and experimental data on which they have been derived.

Breast Neoplasms↗

PubMed2004

Normal-tissue toxicities of thoracic radiation therapy: esophagus, lung, and spinal cord as organs at risk.

The evolution of therapeutic approaches for lung cancer illustrates the trend for treatment intensification, with hopes that dose-intense chemotherapy regimens, higher radiation therapy (RT) doses, or novel fractionation schemes will result in prolongation of survival. Current chemotherapy- and RT-intense regimens may not be intensified further without addressing dose-limiting toxicities such as esophagitis. It is important to understand factors pre-disposing to esophagitis so that strategies to minimize its severity can be investigated. Pulmonary complications such as pneumonitis and fibrosis from RT (with or without chemotherapy) are dose and volume dependent. Methods to better identify the target tissues and improved RT-delivery systems may facilitate increasing target doses or reducing doses to adjacent normal tissues. Biologic predictors may allow clinicians in the future to individualize RT treatment based on a patient's toxicity risk profile. Radiation myelopathy is still the most feared radiation complication of lung cancer treatment. The authors address the known parameters that influence the incidence of thoracic radiation myelopathy and the putative factors that could be considered when a clinician may be required to push the spinal cord dose in favor of tumor control.

Esophagus↗

PubMed2000

Beta blocker therapy for chronic heart failure.

Recent studies have shown that beta blocker therapy improves survival and reduces hospitalizations in patients who have chronic heart failure and left ventricular systolic dysfunction, the majority of whom are under the management of primary care physicians. Appropriate patient selection is essential to the successful initiation of beta blocker therapy. Candidates should be stable in New York Heart Association functional class II or III. Patients with severe heart failure, especially inotrope-dependent and hospitalized patients, and those with hypotension, bradycardia or higher than first-degree heart block are not considered appropriate candidates for beta blocker therapy. Optimal diuresis is essential for maximal tolerability. Beta blockers should be started at the lowest dose, with the dose increased every two to four weeks until the target dose or highest tolerated dose is reached. Close monitoring allows for the detection and appropriate management of side effects, such as hypotension, bradycardia and increased congestion. The treatment goal is long-term improvement of prognosis, rather than immediate improvement of symptoms.

Adrenergic beta-Antagonists↗

PubMed1996

Feasibility and toxicity of interferon maintenance therapy after allogeneic BMT for multiple myeloma: a pilot study of the EBMT.

A pilot study was undertaken in order to determine the feasibility and toxicity of rh-alpha-2b-interferon as maintenance therapy after allogeneic BMT for multiple myeloma. The study incorporated planned dose escalation of interferon in successive patient cohorts from an initial dose of 1 MU three times weekly to a target dose of 3 MU three times weekly. No clinical complications were observed in five patients receiving a dose of 1 Mu three times weekly. At a dose of 2 MU three times weekly, one of seven patients developed acute GVHD, which was fatal. At a dose of 3 MU three times weekly, four of five patients developed acute or chronic GVHD, and the study was therefore terminated at this point. We conclude that the use of interferon in myeloma patients early after allogeneic BMT is associated with a significant risk of GVHD, which is dose-related, and that the maximum tolerated dose in the early post-transplant period is 1-2 MU three times weekly.

Adult↗

PubMed1997

Radiosurgical lesions in the normal human brain 17 years after gamma knife capsulotomy.

OBJECTIVE: To our knowledge, this is the first long-term follow-up study of high-dose single-session irradiation to the human brain and provides new data concerning late tissue reactions after irradiation to small target volumes. The long-term lesional brain changes in 14 patients subjected to bilateral gamma knife capsulotomy for otherwise intractable anxiety disorders were retrospectively analyzed by magnetic resonance imaging. METHODS: The prototype gamma unit was used for the radiosurgical procedure, and the collimators provided rectangular cross-sectional fields with an anteroposterior diameter of 3 mm and a transverse diameter of 5 or 11 mm. Maximum target doses were 120 to 180 Gy. Magnetic resonance imaging was performed 15 to 18 years (mean, 17 yr) after treatment, and dose-volume histograms were calculated for the dose distributions. RESULTS: One patient had been irradiated twice on one side. In all but one of the remaining 27 targets, lesions with a volume of less than 100 mm3 were revealed by magnetic resonance imaging. The volumes of the lesions were confined within the volume corresponding to a minimum dose of approximately 110 Gy, with one exception. In one of three targets receiving a maximum dose of 120 Gy, no lesion was detected. There were no late radiation effects such as cyst formations, telangiectasias, hemorrhagic infarctions, or neoplasms. CONCLUSION: This investigation indicates that a minimum dose of 110 Gy, with the currently used 4-mm collimator, to the edge of the target volume is required to create a lesion. The results prove that gamma knife surgery can be used in functional neurosurgery for producing small permanent lesions in the normal human brain.

Adult↗

PubMed1994

Stereotactic radiotherapy of malignancies in the abdomen. Methodological aspects.

A method for stereotactic high-dose radiotherapy of malignancies in the abdomen has been developed. A stereotactic frame for the body has been developed and a method for fixation of the patient in the frame is described. The reproducibility in the stereotactic system of tumours in the liver and the lung was found to be within 5-8 mm for 90% of the patient set-ups. The diaphragmatic movements were reduced to 5-10 mm, by applying a pressure on the abdomen. An analytical method is used to calculate dose distributions for a continuum of beams in an isocentric treatment technique. The advantage of a heterogeneous target dose is demonstrated and proposed for the present application. A non-coplanar treatment technique, using eight individually shaped beams is proposed and has been used for patient treatments. The dose distribution for a patient with a metastasis in the liver is shown as well as dose volume histograms for the target and the liver.

Abdominal Neoplasms↗