Biomedical subjects

D Tai

Publications and source records attributed to D Tai.

9 recordsLinked to original sources

PubMed1996

Sequential evaluation of portal venous hemodynamics by Doppler ultrasound in patients with severe acute hepatitis.

OBJECTIVES: Portal hypertension may develop in patients with severe acute hepatitis. Sequential changes of portal venous hemodynamics in acute hepatitis is not well understood. This study evaluated portal hemodynamic changes and prognostic values in patients with severe, acute hepatitis. METHODS: Doppler studies, liver function tests, and virology studies were done in the inclusion, the 3rd month, and the 6th month for patients with severe, acute hepatitis. An indocyanine green clearance was done in the inclusion. Doppler portal hemodynamic studies were done in the hilar area by an average of two measurements. RESULTS: A total of 88 consecutive patients was included. Nine of them died. On initial study, fatalities were generally older patients with more delayed indocyanine green clearance, lower portal vein velocity, lower albumin values, higher bilirubin values, longer prothrombin time, and ascites. Using stepwise logistic regression, portal blood flow and prothrombin time were the two independence prognostic factors. By multiple linear regression, portal blood flow was associated with ascites, and average portal blood velocity was associated with bilirubin. During the hospital days, transient, depressed portal blood velocities followed by a hyperdynamic stage were found in survivors. The portal vein velocity changes for fatalities either were kept at a lower level or had a declining pattern. CONCLUSIONS: Doppler ultrasound detects portal hemodynamic changes for patients with severe, acute hepatitis. Sequential portal hemodynamic studies will be helpful for evaluating patients with severe, acute hepatitis.

Acute Disease↗

PubMed1995

High-activity 125I interstitial irradiation in the treatment of pediatric central nervous system tumors: a pilot study.

Malignant pediatric tumors of the central nervous system (CNS) have a poor prognosis, with local failure rates as high as 50%. In an attempt to improve local tumor control, we used stereotactic interstitial therapy with 125I implants in patients with recurrent/secondary or newly diagnosed CNS malignancies. Catheters were placed using computed tomography (CT) guidance; computerized dosimetry was completed with the aid of orthogonal films. Implants delivered 1,000 cGy/day to the tumor periphery (0.5 cm beyond the boundary of enhancement on CT scans), to a total dose of 60 Gy. Hyperfractionated external beam irradiation (HEBI), started 2-4 weeks after removal of implants, delivered total doses of 66-70.4 Gy in 110-cGy fractions twice daily to a 3-cm margin around the implant volume. Eight of the 11 patients with newly diagnosed tumors also received 48.4 Gy HEBI to the craniospinal axis. Tumor regression was noted at 2 months after implantation in the 4 patients treated for recurrent/secondary tumors; local progression was subsequently documented in 2 cases at 6 and 20 months after implantation, while a third patient died 6 months after implantation with no evidence of local recurrence. The remaining recurrent/secondary tumor patient has no evidence of active recurrence 15 months after implantation. Local control was maintained in 9 of the 11 patients treated for primary tumors for a median of 27 months (range 15 to 48+ months). The two local failures occurred at 5 and 7 months after implantation. Six patients are alive without evidence of progressive disease (median = 23 months after implantation). There were no severe acute toxicities, but 7 patients later developed histologically confirmed tumor necrosis. Quality of life assessment (QLA) following initial primary therapy with implantation was evaluated utilizing an established criteria and found to be excellent with only one child showing marked QLA score decrease which was related to neurosurgical intervention for radiation-induced necrosis and dysfunctional family social situation. This small series suggests that stereotactic 125I implantation followed by HEBI merits further evaluation in selected children with supratentorial malignant lesions.

Adolescent↗

PubMed1993

Treatment of choroidal melanoma with I-125 plaque.

PURPOSES: To evaluate efficacy of I-125 episcleral plaque therapy in patients with ocular melanoma and determine survival, eventual visual acuity, and complications. METHODS AND MATERIALS: Between July 1, 1984 and January 1, 1991, 144 patients with diagnosis of ocular melanoma were treated with high activity I-125 episcleral plaques. Tumor volumes ranged from 14 to 3449 mm3. Lesion size included small (n = 15; height < 5 mm, and/or largest basal diameter of 8-16 mm) and large (n = 45; height > 8 mm, and/or largest basal diameter > 16 mm). Apical doses ranged from 74.25 to 83.66 Gy with scleral doses ranging from 41 and 160 Gy. Follow-up has ranged from 25 to 90 months (Med = 46 months). RESULTS: Ocular survival was noted in 130/144. Reasons for enucleation included progressive tumor growth (n = 4), extrascleral extension (n = 4), or blind/painful eye (n = 6), 94 patients developed complications which included cataract (n = 43), optic neuropathy (n = 12), neovascular glaucoma (n = 8) and retinopathies (n = 31). Visual acuity testing pre-episcleral plaque therapy revealed 102 patients with 20/200 vision; at last follow-up 59 patients demonstrated visual acuity testing of 20/200 or better. CONCLUSION: The use of episcleral I-125 plaque therapy allows for safe and effective therapy in patients with ocular melanoma of various size depending on location and probable visual acuity outcome. A total apical dose of 75 Gy given at 60-65 cGy/hour provides durable local control with acceptable complication rates.

Adult↗

PubMed1993

Interstitial iodine 125 and concomitant cisplatin followed by hyperfractionated external beam irradiation for malignant supratentorial glioma. Preliminary experience at the University of Tennessee, Memphis.

Between November 1989 and October 1992, 28 consecutive patients with glioblastoma multiforme (n = 18) or anaplastic astrocytoma (n = 10; includes one patient with oligodendroglioma with anaplastic astrocytoma component) were treated with interstitial iodine 125 (60 Gy over 6 days) and with concomitant cisplatin (via infusion on days 2-6 of the implant), then followed by hyperfractionated external beam irradiation (110 cGy delivered twice daily; 66 Gy planned total dose). Of 26 patients (60%) who received both 125I and HEBI, 15 are alive with no evidence of recurrent disease at a median follow-up of 18 months post-125I (range: 11 to 34 months). Four other disease-free patients succumbed to nontumor-related events. Two patients with local control had distant failure outside the HEBI treatment fields. Overall local control is 77%. Local failure occurred in 6 patients (23%) 2 to 11 months post-125I. Time to disease progression ranged from 4 to 18 months (median: 10 months). Survival (measured from the date of diagnosis) has ranged from 6 to 26 months (median: 15 months). All patients have maintained Karnofsky Performance Status within 20 points of their preimplant status, with the exception of a single patient who, following diagnosis of radiation necrosis and surgical intervention for symptomatic relief, had a 30-point drop in KPS. Radiation necrosis or persistent mass effect were noted by neuroimaging in seven patients, four of whom required surgical intervention following failed medical management. Ototoxicity, nephrotoxicity, peripheral nerve dysfunction, or hematologic toxicities have not been observed. This new innovative treatment approach offers a promising alternative to the normally dismal prognosis for patients with malignant gliomas.

Adult↗

PubMed1991

Concomitant cisplatin and hyperfractionated external beam irradiation for advanced malignancy of the head and neck.

The combination of cisplatin and hyperfractionated external beam irradiation (HEBI), followed by salvage surgery when indicated, was evaluated in patients with advanced stage squamous cell carcinoma of the head and neck. Thirty patients with stage III (n = 5) or IV (n = 25) disease received intravenous cisplatin 100 mg/m2 by 6-hour continuous infusion on days 1, 21, and 42 of HEBI. Radiation fractions of 110 cGy were given twice daily, separated by 4 to 6 hours, beginning within 12 hours after cisplatin delivery. Doses to the primary site ranged from 60 to 76.35 Gy (median: 72.3 Gy), with 60 to 74 Gy to nodal sites. Follow-up ranged from 4 to 28 months (median: 19 months). Clinical complete response of the primary site was seen in 27 of 29 patients (93%), and complete clinical clearance of adenopathy in 20 of 26 (76%). A second biopsy 6 to 8 weeks after completion of treatment showed residual disease in both the primary and nodal sites in three patients, and in only the primary site in one patient. Four patients with persistent adenopathy had pathologic confirmation at surgery. Four patients had recurrence after negative biopsy results 6 to 9 months after treatment biopsy. At present, with median follow-up of 19 months, eight patients (26%) have died secondary to uncontrolled primary or nodal disease. Two patients have died of nonrelated causes. Overall, 10 of 30 patients (66%) remain alive with no evidence of disease. Mucositis and weight loss were the most common side effects of treatment. Seven patients developed significant xerostomia, and four have cisplatin-related hearing loss requiring amplification. The early evidence of excellent response (89% pathologic complete response of primary sites; 78% complete response of nodal sites), coupled with acceptable treatment morbidity, warrants further study of this approach.

Adult↗

PubMed1979

An intercomparison between two methods of obtaining percentage depth doses for irregular shaped fields and comparison of each method with experimental data for 60Co and 10 MV X rays.

Measurements of central ray tissue-air ratio (TAR) for 60Co for a large number of irregularly shaped fields typically encountered in the cancer clinic were compared with TAR values either calculated by the Clarkson method using scatter air ratios or obtained from tables of square field data using the area/perimeter approach. Irregular field shapes included the "L", pentagonal, rectangular, upper and lower mantle and split fields. Agreement between both calculational methods and direct measurement is within +/- 2% if careful attention is given to central ray position as affected by the proper use of off-centre ratios in air. In the case of 10 MV X-rays, eight randomly chosen irregular fields again yielded an average agreement between both methods of calculation and experimental data of less than 1% and an agreement of less than 0.5% between the A/P and Clarkson calculations.

Cobalt Radioisotopes↗

PubMed1978

Californium Cf-252 for pelvic radiotherapy.

Clinical data about therapy concerning tumors of the female gynecological cancers of the cervix, vagina and uterus are reviewed. Dosimetric, laboratory and radiobiological research data form the basis for an approach to such tumors using Cf-252 as a form of boost brachytherapy. Extreme personnel hazards are a real and important consideration and indicate that maximal containment and isolation procedures should be exercised in its use. But it is anticipated that new possibilities for successful radiotherapy of an important cagegory of tumor will be realised by its clinical evaluation and application.

Californium↗

PubMed1977

Method for localizing and calculating vaginal dose in brachytherapy.

Contrast agents in the vagina are being used to determine the position of vaginal surfaces relative to applicators in an effort to assess dose at these sites. Computer treatment planning allows consideration of dose at many more sites than was formerly possible, but dose prescription to critical tumor volumes then becomes of greater importance. Vaginal reference dose points VR, VL, VA, and VP are proposed. With dose specification determined at these points, the problem of low vaginal dose from overly wide vaginal ovoid geometries and related difficulties can be avoided. Attention to central vaginal doses can reduce the probability of central pelvic recurrence in the vagina. We have found the VR, VL doses were much larger than VA, VP doses in standard loaded implant configurations.

Aged↗

PubMedDate not supplied

Justification of maternal serum alphafetoprotein screening in a population with low incidence of neural tube defects.

A prospective study of maternal serum alphafetoprotein (alpha-FP) screening of 9838 women in an area with low prevalence of neural tube defects and predominance of anencephalics revealed that an intervention point of single serum alpha-FP level above 2.8 times the median was appropriate for this population. Ninety per cent of anencephalics and all fetuses with anterior abdominal wall defects were detected. There was no spina bifida among the population screened. Two per cent of the population screened had serum alpha-FP level above this cut-off level. Thirty-two per cent of twin pregnancies, 7 per cent of small-for-gestational age infants and 9 per cent of pregnancies which ended in either abortion or perinatal death in the population screened also had one serum alpha-FP level above this intervention point. The false positive rate was 66 per cent. This false positive rate was only reduced to 63 per cent if instead of one, two serum alpha-FP level above this intervention point was considered abnormal. Using this strategy there was no significant reduction in the detection rate of fetal anomalies and other pregnancy complications. Because of the predominance of anencephalics in this population the diagnosis of fetal anomaly in women with abnormal serum alpha-FP level was made by ultrasound examination alone. The reason amniocentesis was not performed in these patients was to avoid unnecessary loss of normal pregnancies which may result from this procedure.

Anencephaly↗