PubMed Health⌕ Search

Biomedical subjects

A Markoe

Publications and source records attributed to A Markoe.

18 recordsLinked to original sources
PubMed2004

The accuracy of dynamic wedge dose computation in the ADAC Pinnacle RTP system.

The nonphysical wedge is a modality that uses computer-controlled jaw motion to generate wedge-shaped dose distributions. There are Varian enhanced dynamic wedges (EDWs) and Siemens virtual wedges (VWs). We recently commissioned dynamic wedges on both Varian and Siemens LINACs. The beam data, acquired with a Wellhofer chamber array and a Sun Nuclear profiler, are used for modeling in the ADAC Pinnacle system. As recommended by ADAC, only a limited number of beam data is measured and used for beam modeling. Therefore, the dose distributions of dynamic wedges generated by Pinnacle must be examined. Following the commissioning of the dynamic wedges, we used Pinnacle to generate a number of dose distributions with different energies, wedge angles, field sizes, and depths. The computed data from Pinnacle are then compared with the measured data. The deviations of the output factor in all square and rectangular fields are mostly within 2.0% for both EDW and VW. For asymmetric fields, the deviations are within 3%. However, exceptions of differences more than 3% have been found in a larger field and large wedge combinations. The precision of the beam profiles generated by Pinnacle is also evaluated. As a result of this investigation, we present a scope of quality assurance tests that are necessary to ensure acceptable consistency between the delivered dose and the associated treatment plan when dynamic wedges are applied.

Equipment Failure Analysis↗
PubMed2003

Androgen receptor antigen density and S-phase fraction in prostate cancer: a pilot study.

PURPOSE: To determine whether quantitative flow cytometric androgen receptor density expression (MFC ratio) in prostate cancer was associated with S-phase fraction. METHODS: Flow cytometry was performed to determine DNA aneuploidy, S-phase fraction, percentage of androgen receptor (AR)-positive cells, and MFC ratio in prostate cancer patients. RESULTS: MFC ratio showed distinct clustering. Eight patients had a low MFC ratio of 1.78-2.74, while 10 patients had high MFC ratios between 4.99 and 6.48. The S-phase fraction had average values of 11.05 vs 4.92 in tumors with high vs low MFC ratio (P<0.01). CONCLUSION: S-phase fraction was significantly higher in tumors with high AR density.

Aged↗
PubMed2001

Twice-daily prophylactic cranial irradiation for patients with limited disease small-cell lung cancer with complete response to chemotherapy and consolidative radiotherapy: report of a single institutional phase II trial.

Prophylactic cranial irradiation (PCI) has been demonstrated to significantly reduce the incidence of brain relapse from limited disease small-cell lung cancer (LD SCLC), but concerns about neurologic toxicity remain. The purpose of this report was to update a phase II institutional trial that explored the impact of twice-daily PCI on neurologic toxicity as well as outcome for this group of patients. All eligible subjects had documented complete response to induction chemotherapy and consolidative chest irradiation. The whole brain was treated with twice-daily fractions of 1.5 Gy with megavoltage irradiation to an approximate total dose of 30.0-36.0 Gy. Although not devised as a randomized study, approximately half of the eligible patients declined the protocol enrollment of their own volition and were retrospectively evaluated as a "historical" control group regarding the incidence of brain metastases. Fifteen patients accepted twice-daily PCI, with 12 deferring treatment. Median follow-up was 20 months. Disease-free survival at 2 years was 54% with twice-daily PCI versus 0% without any PCI (p = 0.013). Overall survival at 2 years was 62% with twice-daily PCI versus 23% without PCI (p = 0.032). No statistically significant neurologic deterioration was detected in the PCI group posttreatment. Thus, twice-daily PCI should be considered for patients with LD SCLC who achieve a complete response to chemoirradiation. A multi-institutional randomized trial would be necessary before making definitive recommendations.

Brain Neoplasms↗
PubMed2001

The effect of aloe vera gel/mild soap versus mild soap alone in preventing skin reactions in patients undergoing radiation therapy.

PURPOSE/OBJECTIVES: To determine whether the use of mild soap and aloe vera gel versus mild soap alone would decrease the incidence of skin reactions in patients undergoing radiation therapy. DATA SOURCES: Prospective, randomized, blinded clinical trial. SETTING: Radiation therapy outpatient clinic in a cancer center affiliated with a major teaching medical facility. SAMPLE: The mean age of the participants was 56 years. The group consisted of Caucasians (74%) and African Americans (26%). The ethnic mix was non-Hispanic (65%) and Hispanic (35%). METHODS: Prophylactic skin care began on the first day of radiation therapy. Patients cleansed the area with mild, unscented soap. Patients randomized into the experimental arm of the trial were instructed to liberally apply aloe vera gel to the area at various intervals throughout the day. FINDINGS: At low cumulative dose levels < or = 2,700 cGy, no difference existed in the effect of adding aloe. When the cumulative dose was high (> 2,700 cGy), the median time was five weeks prior to any skin changes in the aloe/soap arm versus three weeks in the soap only arm. When the cumulative dose increases over time, there seems to be a protective effect of adding aloe to the soap regimen. IMPLICATIONS FOR NURSING PRACTICE: Skin products used to treat radiation dermatitis vary among institutions. Nurses should be aware that some patients may be predisposed to skin problems. Nurses must be aware of newly developed products and research regarding these products so that effective treatment can be instituted.

Adolescent↗
PubMed2000

Early MRI findings in high grade glioma.

Magnetic resonance imaging (MRI) is more sensitive than computerized tomography in the detection of many intracerebral lesions; however, the significance of some MRI findings may be unclear. Over four years, nine patients, aged 40-79 years, have been encountered whose initial MRI scans were negative or had minimal abnormalities and soon thereafter had high grade glioma. Initial MRI was performed in eight patients for new-onset seizures and one patient for a focal deficit. MRI was negative in four of the patients and mildly abnormal in five of the patients (small areas of increased T2 and/or minimal enhancement). The initial diagnoses usually included inconclusive differentials of stroke and infection with neoplasm less frequently considered. Radiographic progression leading to the diagnosis of high grade glioma became evident on repeat MRI in 1-8 months with six patients showing progression within three months. All patients underwent surgery and had histologic diagnosis of glioma. Although MRI is quite sensitive, four of the initial scans were negative with reasonable quality studies. Conversely, in five of the initial scans, the tumors were detected when so small that the radiographic findings were not typically diagnostic. Glioma must be considered as a possible cause of initial seizures or new neurologic deficits in adults with normal or minimally abnormal MRI. In this group, seizures were the overwhelming hallmark of presentation. In such a clinical situation, close follow-up with short interval repeat MRI should be performed.

Adult↗
PubMed1999

A comparison of 3-D data correlation methods for fractionated stereotactic radiotherapy.

PURPOSE: Stereotactic radiosurgery is currently used to treat patients who are not good candidates for conventional neurosurgical procedures. For treatments of nonvascular tumor cells, it appears that fractionation offers a radiobiological advantage between tumor and normal tissues. Therefore, fractionated stereotactic radiotherapy (FSR) is preferred because it minimizes normal tissue complications and maximizes local tumor control probability. We have implemented a methodology clinically to perform the noninvasive patient repositioning technique. The 3-D data correlation method for high-precision and multiple fraction stereotactic treatments has been presented. METHODS AND MATERIALS: Three different optimization algorithms (Hooke and Jeeves optimization, simplex optimization, and simulated annealing optimization) are evaluated to calculate the transformation parameters necessary for FSR. A least-square object function is created to perform the 3-D data matching process. By minimizing the unconstrained object function value the best fit can be approached for the reference 3-D data sets. Simulation shows that these algorithms deliver results that are comparable to the previously published correlation algorithm (1,2) (singular value decomposition [SVD] method). The advantage for optimization algorithms is easily understood and can be readily implemented by using a personal computer (PC). The mathematical framework provides a tool to calculate the transformation matrix which can be used to adjust patient position for fractionated treatments. Therefore, using these algorithms for a high-precision fractionated treatment is possible without an invasive repeat fixation device and has been implemented clinically. A bite plate system was incorporated to acquire 3-D patient data. With a 3-D digital camera localization device, the patient motion can be followed in real time with the system calibrated to the isocenter. RESULTS: Two types of data sets are utilized to study the correlation results. One is using the digitized patient data which were retrieved clinically. The other is using the randomly generated data sets. Simulation errors for the optimization algorithms are all less than 1 mm in translation and less than 1 degree in rotation. Currently, FSR is performed using special designed repeat fixation devices which assure reproducible patient position for multiple fractions of radiation treatment. Clinical results indicated that this technique provided excellent treatment results. CONCLUSION: Three optimization algorithms have been applied and evaluated in calculating the transformation parameters between two 3-D contours or digitized data points. The mathematical functions behind these optimization algorithms are straightforward and can be easily implemented. When incorporated with the proper CT/MR image data with an electronic portal imaging (EPI) system, this process can possibly verify the patient's treatment position whenever there is doubt about the movement during the treatment procedure.

Algorithms↗
PubMed1999

Prognostic factors and survival in patients with spinal cord gliomas after radiation therapy.

The purpose of this study was to determine the impact of various prognostic factors on survival in spinal cord gliomas treated with radiation. Fifty-three patients with spinal cord gliomas irradiated at three major institutions were studied. Fifty-one patients were classified as having ependymoma, astrocytoma, or both. Two patients were classified as having gliomas (otherwise unspecified). Eleven patients had complete resection of their tumor. Biopsy or partial resection was done in the remaining patients. All patients received external beam radiation. Information on these patients was placed in a central database file and analyzed for the effect of several prognostic factors on survival. Overall survival of the entire group was 76.9% and 61.5% at 5 and 10 years, respectively. Pathologic status significantly affected survival (p = 0.03). Patients with ependymomas had a 5-year survival of 93.8% and a 10-year survival of 67.5%. Patients with astrocytoma had a 5-year survival of 64.2% and a 10-year survival of 54%. Univariate analysis showed pathology and the presence of cysts (p = 0.038) to significantly affect survival. Age, sex, location of the primary, extent of surgery radiation dose, and number of involved segments did not affect survival. On multivariate analysis, astrocytic pathology, involvement of more than five segments, male sex, and the absence of cysts (in or adjacent to the tumor) were associated with a significantly inferior survival. This study confirms the importance of pathology and number of segments involved in determining outcome or survival. The presence of cysts adjacent to or within the tumor was found to be associated with an improvement in survival.

Adolescent↗
PubMed1998

The importance of postoperative radiation therapy in multimodality management of locally advanced breast cancer: a phase II trial of neoadjuvant MVAC, surgery, and radiation.

PURPOSE: To determine the impact of postoperative radiation on locoregional relapse and overall survival rate in a multimodality protocol for locally advanced breast cancer (LABC). MATERIAL AND METHODS: Of the patients entered in the protocol, 55 were evaluable. Treatment consisted of: neoadjuvant MVAC (methotrexate, vinblastine, adriamycin, and cisplatin) until a maximum response had been achieved; modified radical mastectomy; 6 courses of postoperative adjuvant MVAC chemotherapy, and chest wall irradiation (CWXRT). Multivariate analysis of locoregional response and overall survival was done. RESULTS: Of the total, 42 patients received chest wall radiation; 28 of these also received radiation to regional lymph nodes. Chest wall doses ranged from 45 Gy to 50.4 Gy to the whole chest wall, with 31 patients receiving an additional chest-wall boost. The incidence of locoregional relapse with and without radiation was 7% vs. 31%, respectively (p = 0.026). An overall survival benefit was seen in those receiving radiation, with a mean overall survival of 50 months vs. 20 months, and a 3-year overall survival of 88% vs. 46% with and without radiation, respectively (p = 0.003). Multivariate analysis showed that overall survival was affected by the presence of pathological CR (p = .047), the number of pre-operative chemotherapy cycles (p = .036) and whether or not they received radiation (p = 0.003). Neither the interval between surgery and radiation, technique of radiation, nor radiation modality significantly affected local control. CONCLUSION: The significant improvement in local regional control and overall survival with the addition of radiation suggests that radiation should be an integral part of multimodality management of locally advanced breast cancer.

Adult↗
PubMed1998

Dose volume histogram analysis of the gamma knife radiosurgery treating twenty-five metastatic intracranial tumors.

Treating multiple brain metastatic sites in Gamma Knife radiosurgery is not uncommon. Most metastases can be treated with few or even one single shot. Occasionally we have patients returning for retreatment for different intracranial metastatic sites at different times. Dose distribution for these metastases are prescribed locally without considering the previous dose contribution. We present a study which simultaneously calculates the dose distribution of 25 randomly placed shots distributed inside the intracranial region. The Dose Volume Histogram (DVH) is plotted to study the coverage of the tumor sites and normal tissues. We have calculated ten DVH studies and show that 50% of the brain volume receives less than 500 cGy for the maximum tumor dose of 40 Gy, and the dose gradient is extremely steep. This DVH analysis shows that the Gamma Knife radiosurgery is a good treatment modality to control the local tumors while maintaining normal brain function, even for the large number of brain metastasis treated at different times.

Brain↗
PubMed1997

Dose-volume histograms for bladder and rectum.

PURPOSE: A careful examination of the foundation upon which the concept of the Dose-Volume Histogram (DVH) is built, and the implications of this set of parameters on the clinical application and interpretation of the DVH concept has not been conducted since the introduction of DVHs as a tool for the quantitative evaluation of treatment plans. The purpose of the work presented herein is to illustrate problems with current methods of implementing and interpreting DVHs when applied to hollow anatomic structures such as the bladder and rectum. METHODS AND MATERIALS: A typical treatment plan for external beam irradiation of a patient with prostate cancer was chosen to provide a data set from which DVH curves for both the bladder and rectum were calculated. The two organs share the property of being shells with contents that are of no clinical importance. DVHs for both organs were computed using a solid model and using a shell model. Typical treatment plans for prostate cancer were used to generate DVH curves for both models. The Normal Tissue Complication Probability (NTCP) for these organs is discussed in this context. RESULTS: For an eight-field conformal treatment plan of the prostate, a bladder DVH curve generated using the shell model is higher than the corresponding curve generated using the solid model. The shell model also has a higher NTCP. A six-field conformal treatment plan also results in a higher DVH curve for the shell model. A treatment plan consisting of bilateral 120-degree arcs, results in a higher DVH curve for the shell model, as well as a higher NTCP. CONCLUSION: The DVH concept currently used in evaluation of treatment plans is problematic because current practices of defining exactly what constitutes "bladder" and "rectum." Commonly used methods of tracing the bladder and rectum imply use of a solid structure model for DVHs. In reality, these organs are shells and the critical structure associated with NTCP is obviously and indisputably the shell, as opposed to its contents. Treatment planning algorithms for DVH computation should thus be modified to utilize the shell model for these organs.

Humans↗
PubMed1996

Retrospective epidemiologic analysis of patients diagnosed with intracranial meningioma from 1977 to 1990 at the Jackson Memorial Hospital, Sylvester Comprehensive Cancer Center: the Jackson Memorial Hospital Tumor Registry experience.

A descriptive analysis was performed of the Tumor Registry data for intracranial meningioma by the Jackson Memorial Hospital, University of Miami School of Medicine Tumor Registry. A total of 108 cases of intracranial meningioma was collected and reviewed. Overall survival for 2, 5, and 10 years was 82, 72, and 60%, respectively. There was no difference in survival for males and females at 5 years, nor any difference in survival for race or ethnicity. There was a trend for improved survival for the young age group (18-55 years).

Adult↗
PubMed1994

Phase I trial of low dose N-phosphonacetyl-L-aspartic acid and high dose 5-fluorouracil administered concomitantly with radiation therapy for unresectable localized adenocarcinoma of the pancreas.

BACKGROUND: Preclinical and clinical data suggest that N-phosphonacetyl-L-aspartic acid (PALA) can augment the cytotoxic effects of 5-fluorouracil (5-FU). In addition, the combination of 5-FU and radiation therapy has been used with success in prolonging survival and providing palliation of symptoms in patients with advanced unresectable pancreatic carcinoma. This Phase I study was undertaken to determine the feasibility and evaluate the qualitative and quantitative toxicities of PALA and escalating doses of 5-FU administered concomitantly with radiation therapy in patients with locally advanced nonmetastatic pancreatic adenocarcinoma. METHODS: Ten previously untreated patients with advanced nonmetastatic adenocarcinoma of the pancreas were treated with 250 mg/m2 of PALA given as an intravenous bolus followed 24 hours later by 5-FU, which was given by continuous 24-hour infusion every week. The 5-FU doses were assigned according to a Phase I drug escalation (1000 mg/m2, 1300 mg/m2, and 1700 mg/m2). Radiation therapy was delivered concurrently with chemotherapy at a dose of 180 cGy per fraction (900 cGy per week) over 6 1/2 weeks. PALA and 5-FU were continued weekly after the end of radiation therapy, with disease assessments made every 8 weeks. Chemotherapy was continued until the disease progressed. RESULTS: All 10 patients were evaluable. The maximum tolerated dose (MTD) of 5-FU was 1300 mg/m2. Two of the four patients treated at the 1700 mg/m2 dose level experienced dose-limiting toxicities, nausea/vomiting and mucositis, respectively. Toxicities were mild to moderate at the 1000 mg/m2 and 1300 mg/m2 dose levels. Two patients treated with 5-FU at the 1300 mg/m2 dose level had complete responses, and one patient treated at the 1700 mg/m2 dose level had a partial response. The median survival was 12.5 months, and four patients survived more than 1 year. CONCLUSIONS: PALA and 5-FU administered concomitantly with radiation therapy is an active regimen in locally advanced, unresectable pancreatic cancer. Dose-limiting toxicities are nausea/vomiting and mucositis. The MTD of 5-FU is 1300 mg/m2. The regimen is well tolerated and administered in an outpatient setting.

Adenocarcinoma↗
PubMed1994

Melanoma in a southeastern Hispanic population.

A descriptive analysis was performed of the Tumor Registry data for malignant melanoma in Hispanics ascertained by the Jackson Memorial Hospital (JMH), University of Miami School of Medicine Tumor Registry. A total of 54 cases of melanoma in Hispanics was collected and reviewed. Most of the lesions of melanoma occurred on the trunk, arm, shoulder, leg, and hip. Seventy percent of the Hispanics presented with local stage disease; 26% presented with both regional and distant disease. Local stage had the best 5-year survival (87%). In regional and distant disease combined, the survival was better for Hispanics than non-Hispanics (p = 0.01). In addition, it was found that the Hispanics in the over 50-year-old age group did better than the non-Hispanics in the same group (p = 0.05). Comparison of survival between Hispanic males and females shows that Hispanic females have a 5-year survival of 86% compared to 56% for Hispanic males (p = 0.017).

Abdomen↗
PubMed1992

Descriptive analysis of the tumor registry experience for malignant melanoma from 1977 to 1986 at the University of Miami School of Medicine/Jackson Memorial Hospital.

A descriptive analysis was performed of malignant melanoma data ascertained by the University of Miami School of Medicine/Jackson Memorial Hospital (UM/JMH) Tumor Registry. A total of 376 melanoma cases were collected and reviewed. Most of the melanoma lesions occurred on the trunk, especially in the 40- to 49- and 50- to 54-year-old age groups. Local-stage cases had the best 5-year survival--77%. The difference in survival between local-stage case and regional- and distant-stage cases was statistically significant (p = 0.0000). In males with local-stage disease, lesions on the trunk were associated with better survival than lesions at other sites (p = 0.04). In females with local-stage disease, survival was 68% for 5 years for trunk sites vs. 87% for other sites (p = 0.05). In local-stage disease, the overall 5-year survival was 85%.

Adult↗
PubMed1991

Ameloblastoma of the jaw. Treatment with radiation therapy and a case report.

Ameloblastoma of the jaw is an aggressive benign tumor of epithelial origin that has generally been treated surgically even for metastases. This article is a review of the literature and a report of a previously unpublished case. Despite earlier reports, it is suggested that the available data clearly indicate that it is a radiosensitive tumor. In this report, specific recommendations for radiation therapy are outlined, and guidelines for treatment planning, radiation dosage, and fractionation expected outcome and follow-up are given.

Ameloblastoma↗
PubMed1990

The radiation therapy of early stage cutaneous T-cell lymphoma.

Results of different radiotherapy schedules used for early stage (T1-2, N0-1, M0) cutaneous T-cell lymphoma (CTCL) are compared in a series of 45 patients (22 patients treated with high dose total skin electron beam therapy (TSEB) with curative intent, 18 patients treated with palliative radiotherapy, and 5 patients treated with high dose local electron beam). At 3, 5, and 10 years after diagnosis the high dose TSEB treatment group had a probability of overall survival of 91%, 86%, and 75%, respectively, compared with 94%, 88%, and 88% for the palliative treatment group. The complete response (CR) rate for the high dose TSEB treatment group was 82% (18/22), compared with a 57% (4/7) complete response rate for seven patients in the palliative group who received low dose TSEB (less than 25 Gy in 6-7 weeks) followed by daily application of topical mechlorethamine hydrochloride (HN2). However, the probability of continued remission at 3, 5, and 10 years was 44%, 44%, and 33%, respectively, for the high dose TSEB group and 25%, 25%, and 0%, respectively, for the low dose TSEB + HN2 group. The median disease-free survival was 17.5 months for the high dose TSEB group versus 5.5 months for the low dose TSEB + HN2 group. The five patients who were treated with high doses of local electrons to a single local field had an overall survival rate of 80%, a median survival rate of 64 months, and a median length of continued remission of 31 months. These results indicate that high-dose electron beam can result in long-term disease-free survival in patients with localized and limited extent skin involvement with cutaneous T-cell lymphoma.

Adult↗
PubMedDate not supplied

Dose escalation in chemoradiation for anal cancer: preliminary results of RTOG 92-08.

PURPOSE: Radiation Therapy Oncology Group experience with chemoradiation for anal cancer has shown a local failure rate of 20% to 30% with radiotherapy doses of 45 to 50 cGy. This study was undertaken to assess the effect of higher radiotherapy doses on toxicity, local control, and survival in this disease. MATERIALS AND METHODS: Forty-seven patients with anal cancers measuring > or = 2 cm were treated with a concurrent combination of two cycles of 5-fluorouracil infusion (1000 mg/m2 over 24 hrs for 4 days) and mitomycin C (10 mg/m2 bolus) plus 59.6 Gy of pelvic and perineal radiotherapy administered over 8.5 weeks, including a 2-week rest period. Patients were followed for toxicity, disease status, and colostomy-free survival. Twenty-three (49%) patients had advanced (T3-4) primary tumors; 42 (92%) patients had NO disease, and 36 (77%) patients had squamous histology. For perspective, a comparative analysis was made with 147 patients treated on the previous RTOG protocol for anal cancers (RTOG 87-04) with identical chemotherapy but radiotherapy doses of 40 to 50.4 Gy. RESULTS: Transient hematologic and skin toxicity predominated during treatment or in early follow-up. One patient developed septicemia and died of multiple gastrointestinal toxicities. Twelve (26%) patients had greater than grade 3 complications and, of these, 9 (20%) had hematologic side effects alone. A comparative analysis with 147 patients treated on RTOG protocol 87-04 showed no significant differences in pretreatment characteristics of disease extent, performance status, or histology. A mandatory 2-week split in the current chemoradiation protocol contrasted with 12% of patients having a 2-week or greater treatment break in RTOG 87-04. Patients treated on the current protocol (RTOG 92-08) had a markedly lower incidence of > or = grade 3 dermal toxicity (34% vs. 55%) but a higher colostomy rate at 1 year (23% vs. 6%) and at 2 years (30% vs. 7%) compared with RTOG 87-04. CONCLUSIONS: Numerical increases in radiotherapy dose over those used in conventional chemotherapy regimens for anal cancers do not appear to increase local control when given in split-course fashion. For higher radiotherapy doses (> 50 Gy) to increase local control, radiation may have to be given in continuous fashion, which almost certainly means that our threshold of acceptable acute toxicity, particularly dermal toxicity, may have to be raised.

Adult↗