PubMed Health⌕ Search

Biomedical subjects

M Gillin

Publications and source records attributed to M Gillin.

At least 19 recordsLinked to original sources
PubMed2001

Comparision of four different dose specification methods for high-dose-rate intracavitary radiation for treatment of cervical cancer.

PURPOSE: To compare the dose delivered to target tissues and dose-limiting structures as defined by specific dose points with high-dose-rate intracavitary brachytherapy using tandem and ring or tandem and ovoids applicators, and to provide a reasonable approach to dose optimization. METHODS AND MATERIALS: Dosimetry was obtained using four different dose specifications: (1) 100% of the dose prescribed in a tapered fashion along the tandem and 140% at the ovoid/ring surface, (2) 100% of the dose prescribed along the tandem and 100% at the ovoid/ring surface, (3) 100% of the dose prescribed to point A without any additional applicator specification points, and (4) nonoptimized plan using relative dwell weighting to simulate classic Fletcher low-dose-rate (LDR) loading with the dose specified at point A. Point doses were recorded at A, B, and T (cervical tumor point), ICRU rectum, and ovoid/ring surface. RESULTS: For the tandem and ovoids applicators, significant differences were found among the four different dose specification methods for point T and vaginal mucosal doses. When the dose was optimized to point A alone, the ovoid dwell weights were reduced, resulting in higher point T doses and underdosing of the vaginal mucosa. Fixed weighting based on Fletcher LDR loading specifications resulted in higher vaginal mucosa doses. For the tandem and ring applicators, significant differences were observed for vaginal mucosal doses and the ICRU rectal dose. Optimization to point A alone resulted in widely varying dosimetric distributions and vaginal mucosa doses up to 632% of the prescription dose. With nonoptimized fixed weighting, the vaginal wall dose and ICRU rectal dose were increased. CONCLUSION: Prescribing to dose optimization points in a tapered fashion along the tandem and at the ovoid/ring surface results in a pear-shaped dose distribution resembling classic LDR systems. The other dose specification methods may result in underdosing of important target tissues or overdosing of adjacent dose-limiting structures.

Brachytherapy↗
PubMed2001

Comparison of traditional low-dose-rate to optimized and nonoptimized high-dose-rate tandem and ovoid dosimetry.

PURPOSE: Few dose specification guidelines exist when attempting to perform high-dose-rate (HDR) dosimetry. The purpose of this study was to model low-dose-rate (LDR) dosimetry, using parameters common in HDR dosimetry, to achieve the "pear-shape" dose distribution achieved with LDR tandem and ovoid applications. METHODS AND MATERIALS: Radiographs of Fletcher-Suit LDR applicators and Nucletron "Fletcher-like" HDR applicators were taken with the applicators in an idealized geometry. Traditional Fletcher loadings of 3M Cs-137 sources and the Theratronics Planning System were used for LDR dosimetry. HDR dosimetry was performed using the Nucletron Microselectron HDR UPS V11.22 with an Ir-192 source. Dose optimization points were initially located along a line 2 cm lateral to the tandem, beginning at the tandem tip at 0.5-cm intervals, ending at the sail, and optimized to 100% of the point A dose. A single dose optimization point was also placed laterally from the center of each ovoid equal to the radius of the ovoid (ovoid surface dose). For purposes of comparison, dose was also calculated for points A and B, and a point located 1 cm superior to the tandem tip in the plane of the tandem, (point F). Four- and 6-cm tandem lengths and 2.0-, 2.5-, and 3.0-cm ovoid diameters were used for this study. Based on initial findings, dose optimization schemes were developed to best approximate LDR dosimetry. Finally, radiographs were obtained of HDR applications in two patients. These radiographs were used to compare the optimization schemes with "nonoptimized" treatment plans. RESULTS: Calculated doses for points A and B were similar for LDR, optimized HDR, and nonoptimized HDR. The optimization scheme that used tapered dose points at the tandem tip and optimized a single ovoid surface point on each ovoid to 170% of point A resulted in a good approximation of LDR dosimetry. Nonoptimized HDR resulted in higher doses at point F, the bladder, and at points lateral to the tandem tip than both the optimized plan or the LDR plan. CONCLUSION: Optimized HDR allows specification of dose to points of interest, can approximate LDR dosimetry, and appears superior to nonoptimized HDR treatment planning, at least at the tandem tip. An optimization scheme is presented that approximates LDR dosimetry.

Brachytherapy↗
PubMed1996

CT-guided interstitial implantation of gynecologic malignancies.

PURPOSE: To establish the efficacy of computed tomography (CT)-based planning and analysis of transperineal implants. METHODS AND MATERIALS: For patients with bulky disease or geometrically unfavorable anatomy, transperineal interstitial implantation of gynecologic tumors offers an alternative to standard intracavitary techniques. Control of dose rate and total dose distributions to produce a homogenous, low dose rate implant presents a challenge to the radiation oncologist in these complex implants, as does the relationship of these distributions to the patients's anatomy. We have used CT imaging following needle implantation, prior to source loading, in 25 patients (28 implants), as an aid in both the planning of the implant and the analysis of the dosimetry. RESULTS: The spatial relationship between the needles and the normal anatomy can be clearly defined, despite the presence of some artifacts. Tumor volume is less clearly visualized but the adequacy of needle placement can be assessed and adjusted if necessary. Modifications of the planned source placement, based upon the location of specific needles and critical structures, can be made prior to loading the patient. Dose rate and total dose distributions are displayed with the appropriate anatomy on axial images and on reconstructed sagittal and coronal planes. Multiple points of dose specification for the rectum and the bladder are easily defined. Dose rate adjustment can be made by selectively changing the activity associated with a particular needle or needles. Multiple implants as well as external beam irradiation can also be integrated. CONCLUSIONS: CT-based dosimetry has permitted intelligent planning decisions to be made prior to and during these implants. It has further allowed more accurate anatomically based dosimetric analysis, with visualization and control of dose rate and total dose distributions displayed together with the patient's anatomy. This more elaborate analysis should ultimately lead to a better understanding of the reasons for local control and complications and their relationships to dose rate, total dose, and volume.

Brachytherapy↗
PubMed1993

Radiation Therapy Oncology Group: radiosurgery quality assurance guidelines.

A multidisciplinary Radiation Therapy Oncology Group (RTOG) task force has developed quality assurance guidelines for radiosurgery. The purpose of the guidelines are fourfold: (1) To ensure that participating institutions have the proper equipment and appropriate technique(s) to administer radiosurgery; (2) to outline a standard data set for each treated patient to assess protocol compliance; (3) to define minor and major deviations in protocol treatment; and (4) to set forth clinical data necessary to determine treatment efficacy, including failure patterns, and treatment toxicity. These guidelines are being implemented into active and developing radiosurgery protocols.

Brain Neoplasms↗
PubMed1991

Measurement of skin dose in primary irradiation of maxillary sinus carcinoma.

Subcutaneous involvement frequently occurs in maxillary sinus carcinoma. Radical resection does not include removal of the skin at risk. In standard postoperative wedge-pair treatment plans, the surface dose is dependent upon beam weighting, beam energy, and patient contour. Thermoluminescent dosimetry (TLD) measurements were performed to evaluate the surface dose of patients undergoing postoperative irradiation of maxillary sinus carcinoma following primary resection. When 60 Gy was delivered to isocenter with a 45 degrees wedge pair and 6 MV photons with 1 cm bolus, the subcutaneous tissues at risk received approximately 30 Gy. Based upon presented TLD measurements, supplemental electron beam therapy to the subcutaneous tissues if primarily involved should be considered.

Aged↗
PubMed1988

Mammary carcinoma developing after radiotherapy and chemotherapy for Hodgkin's disease.

Two patients developed breast cancer after treatment of Hodgkin's disease. Both had received mediastinal irradiation 13 to 15 years, respectively, before the diagnosis of breast carcinoma. One patient had synchronous bilateral breast cancer when the diagnosis was made. Discussed is the risk of mammary carcinoma as a second malignant neoplasm in patients treated for Hodgkin's disease.

Adult↗
PubMed1977

Aerosolized terbutaline sulfate--an evalution of efficacy and side effects in patients with reversible airway disease.

Aerosolized terbutaline sulfate at a dose of 0.50 mg has been shown to produce significant bronchodilation in patients with reversible airway disease. The purpose of this study was to evaluate the safety and efficacy of 0.50 mg terbutaline aerosol used on a regular dosage schedule over a six-week period. Sixteen ambulant patients with chronic obstructive pulmonary disease with a component of reversible airway disease were evaluated. The patients were tested at two-week intervals during a six-week period. The patients abstained from all bronchodilatory medications for at least 10 hours prior to the time of evaluation. The evaluation consisted of baseline pulmonary function tests, ECG, CBC, urinalysis, and renal and liver function tests. After the terbutaline was administered, a rhythm strip and pulmonary function tests were repeated at 5, 15, 30, 60, 120, and 180 minutes. Throughout the six-week study, there was a statistically significant increase in FEV1.0 and MMEFR (P less than 0.001): deltaFEV1.0 (ml) 740 (63%) 550 (45%) 340 (25%) 320 (25%) deltaMMEFR (liters/min) 42 (74%) 29 (46%) 28 (43%) 36 (42%). No abnormal laboratory results or paradoxical bronchospasm were noted during the study period; however, sympathomimetic side effects were observed. Aerosolized terbutaline sulfate (0.50 mg) when used on a regular schedule over a six-week period is effective in the treatment of reversible airway disease.

Adult↗
PubMed1976

A long-term study of low-dose aerosolized terbutaline sulfate.

The purpose of this study was to evaluate the safety and efficacy of a new lowdose terbutaline sulfate aerosol (375 micrograms) over a six-week period. The question of drug tolerance was also evaluated. Twenty-four ambulant patients with chronic obstructive pulmonary disease with a component of reversible airway disease was evaluated. The patients were tested at two-week intervals during a six-week period. The patients abstained from all bronchodilatory medications for at least 10 hours prior to the time of evaluation. The evaluation consisted of baseline FEV1 and MMEFR determinations, ECG, CBC, urinalysis, and renal and liver function tests. After the terbutaline was administered, a rhythm strip and pulmonary function tests were repeated at 5, 15, 30, 60, 120, and 180 minutes. Throughout the six-week study there was a statistically significant increase in FEV1 and MMEFR, (P less than 0.001). No change was noted in the systolic blood pressures; however, heart rate and diastolic blood pressure decreased significantly. No drug tolerance, paradoxical bronchospasm, subjective side effects, no abnormal laboratory results were noted during the study period.

Adult↗
PubMed1976

Oral terbutaline sulfate--amelioration of exercise-induced bronchospasm.

Bronchospasm can be induced in asthmatics when exercised according to a multistage branching treadmill protocol that allows them to achieve 80 per cent of their age-predicted maximal heart rate. This present study was undertaken to investigate the effect of oral terbutaline sulfate in ameliorating exercise-induced bronchospasm. Ten asthmatics were exercised, and FEV1.0 and MMEFR were assessed while standing, using a Jones Pulmonar II waterless spirometer at 5, 15, and 30 minutes after exercise. Three hours before exercise, the subjects received no medication, oral placebo, or 5 mg terbutaline sulfate orally. At all time intervals after exercise, the pulmonary function of the group pretreated with oral terbutaline was superior when compared to the no-medication group (P less than 0.01) and to the placebo-treated group (P less than 0.05). Oral terbutaline appeared to normalize the exercise tolerance of the asthmatics and restore physiologic pulmonary airway conductance by the parameters of FEV1.0 and MMEFR.

Administration, Oral↗
PubMed1976

Peripheral plasma determinations of prostaglandin E in asthmatics.

Prostaglandins, unsaturated fatty acid derivatives with diversified pharmacologic activity, have recently been implicated in the pathophysiology of reversible airway disease. This study attempted to elucidate baseline prostaglandin E (PGE) plasma levels in asthmatics and the change in these levels after stimulation by a beta-adrenergic agent. Fourteen stable, ambulant patients with reversible airway disease and 28 nonatopic control subjects were studied. All had baseline PGE levels performed. The asthmatics were asked to abstain from all medication for 10 hr prior to evaluation. After baseline evaluation consisting of plasma PGE determination, pulmonary function test, blood pressure, and heart rate, 375 mug of aerosolized terbutaline sulfate was administered to 8 of the asthmatics plus 4 of the nonatopic control subjects; the above measurements were repeated at 15, 30, and 60 min after administration. There was a statistically significant difference in baseline plasma PGE levels between the asthmatics (PGE = 432 +/- 81) and the nonatopic control subjects (PGE = 89 +/- 9) (p less than 0.002). Following terbutaline administration, there was no significant change observed in PGE levels in asthmatic or in control individuals (asthmatics: 0 min, 570, 15 min, 513, 30 min, 514, 60 min, 608; normal subjects: 0 min, 138, 15 min, 137, 30 min, 143, 60 min, 214). In summary, we observed a significant difference in baseline PGE levels between asthmatic and nonatopic control persons. No change, however, was noted in PGE levels after beta-adrenergic receptor stimulation. This observation is consistent with the current hypothesis that beta-adrenergic agents act independently of prostaglandins to increase adenyl cyclase and modify bronchiole smooth muscle tone.

Adult↗
PubMed1976

Evaluation of exercise-induced bronchospasm in the adult asthmatic.

It has been shown that most asthmatics respond to exercise with bronchospasm. This study was undertaken to develop a safe and reliable method for quantifying exercise-induced bronchospasm in the asthmatic adult. Five normal adult volunteers and 12 stable asthmatics were exercised to 80% of their predicted maximal heart rate according to a multistage branching treadmill protocol. Their responses in terms of forced expiratory volume in 1 sec (FEV1) and maximum midexpriatory flow rate (MMEFR) at 5, 15, and 30 min after exercise were assessed, while standing, with a Jones Pulmonar II waterless spirometer. This submaximal stress test was chosen because 80% of predicted maximal heart rate could be obtained by all individuals and allowed the asthmatics to exercise long enough for inducible bronchospasm to occur. Audible wheezing was induced in 100% of the asthmatics and in none of the nonasthmatics. In the normal individuals, FEV1 and MMEFR increased signficantly during the postexercise period. When compared to normal subjects, the 12 asthmatic patients demonstrated a significant reduction in FEV1 an MMEFR (deltaFEV1 : 5 min, -300; 15 min, -304; o9 min, -208 ml; -18%, -17%, and -15%; deltaMMEFR: 5 min, -15; 15 min, -9; 30 min, -1L/M; -23%, -18%, and -6%) (p less than 0.01). The use of a rigidly controlled exercise stress with a cardiovascular endpoint in the measurement of FEV1 and MMEFR in the postexercise period appears to be a useful tool in assessing the presence and severity of exercise-induced bronchospasm in the adult asthmatic.

Adult↗
PubMed1976

Measurement of plasma prostaglandins during exercise-induced bronchospasm.

Bronchospasm following exercise is a phenomenon which occurs in most patients with reversible airway disease. The pathophysiologic mechanism leading to this bronchoconstriction with exercise has not yet been defined. Recently, prostaglandins have been implicated in the etiology of asthma. The purpose of this investigation was to determine changes in plasma prostaglandins occurring during exercise-induced asthma. Eight ambulant asthmatics were chosen for baseline pulmonary spirometry and peripheral venous blood prostaglandin E and F levels. The asthmatics were then exercised to 80% of their age-predicted maximal heart rate via a multistage branching treadmill protocol. At 5, 15, and 30 min following exercise, pulmonary spirometry was again performed and peripheral venous blood collected at the indicated times. Clinical bronchospasm as characterized by audible wheezing and greater than 15% decrease in FEV1 and MMEFR was obtained in all of the asthmatics. Peripheral PGE and PGF2alpha determinations following this exercise protocol were not altered significantly: (PGE: 0 min, 238; 5 min, 185; 15 min, 248; 30 min, 256 pg/ml); (PGF2alpha: 0 min, 50; 5 min, 24; 15 min, 25; 30 min, 17 pg/ml) (p less than 0.1). In summary, no significant change in peripheral blood prostaglandin E and F2alpha levels as determined by radioimmunoassay was noted at the time of exercise-induced bronchospasm.

Bronchial Spasm↗
PubMed1976

Paradoxic bronchospasm after inhalation of isoptroterenol.

Paradoxic bronchospasm induced by adrenergic aerosols, especially isoproterenol, is a well-known clinical entity. It normally occurs in patients who abuse the use of isoproterenol, but has also been reported in a small group of other patients. This study attempted to identify patients who exhibit paradoxic bronchospasm after administration of aerosolized isoproterenol. Forty-one stable, ambulant asthmatics, whose FEV 1.0 was less than 70 percent of predicted normal were studied. None of the asthmatics had taken isoproterenol for one year prior to evaluation. Baseline pulmonary function tests (FVC,FEV 1.09 MMEFR), blood pressure and ECG rhythm strips were recorded, and repeated at 15, 30, 60 and 120 min after administration of isoproterenol. Twenty-nine of the asthmatic patients had the expected normal response ( delta FEV 1.09 15 min: + 579; 30 min: + 464; 60 min: + 372; 120 min: + 307 ml: + 44, + 36, + 23 and + 24 percent) (delta MMEFR, 15 min: + 37; 60 min: + 29; 120 min: + 18L/Min: + 75, + 69, + 47 and + 37 percent). Twelve asthmatic patients (29 percent) had paradoxic bronchospasm (delta FEV 1.09 15 min: - 38; 30 min: - 60; 60 min: - 175; 120 min: - 27 ml; -1, -4, - 10 and - 4 percent) (delta MMEFR - 15 min: - .5; 30 min: - 3; 60 min: - 9; 120 min: - 2L/min; + 4, - 3, - 6 and - 5 percent, P less than 0.001).

Adult↗
PubMed1976

Decreased prevalence of immediate hypersensitivity (atopy) in a cancer population.

It has been suggested that the atopic population has decreased risk of cancer. This investigation examined the cumulative prevalence of atopy in a population with neoplastic disease and compared this with the prevalence of atopy in an age-matched control group and with published estimates of atopy in the general peopulation. Seventy-four patients with neoplastic disease and 86 patients without cancer were evaluated. The subjects were given a standard allergic questionnaire which evaluated them with regard to a history of allergic symptoms, hives, eczema, frequent colds, frequent unexplained rashes, hay fever, and asthma. All were skin tested with a representative group of regionally significant allergens. There was a 15-fold decrease in prevalence of atopy in the cancer population, compared with the control group and compared with published estimates of atopy in the general population.

Adult↗