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PubMed1978

Dose reduction in mammography.

The Min-R system is more than a satisfactory substitute for xerography. At equal distances, the images obtained are equivalent. Radiation exposure was 25 per cent of xerography, a significant reduction in exposure. By using a long cone and improving geometry, superior images were obtained in 4 per cent of 400 comparison patients. If mammography is to be used as an early detection device in patients with carcinoma of the breast, modalities with lower exposure requirements must be used. Min-R, a new film screen system, fulfills the requirement of reduced patient exposure without loss of diagnostic accuracy.

Female↗
PubMed1996

[Dose reduction in computerized tomography with a new scan procedure].

A new investigation technique in computed tomography--the Smart Scan process--and the associated reduction in tube current are discussed. In addition, the reduced dosage values resulting from the reduced current values are compared with those of a standard measurement and image characteristics such as picture unit noise are evaluated. By means of three special water phantoms with dimensions corresponding to those of actual patient geometries and a pool of 183 patients, the Smart Scan process was tested by the control algorithm implemented on a spiral computer tomograph. The dosage values with and without the Smart Scan being activated were determined. Dosage reductions of up to 18% can be realized with this new examination technique. In particular, patients with transverse oval head profiles will benefit from this modality.

Adolescent↗
PubMed2001

The potential for reduction of radiation doses to patients undergoing some common X ray examinations in Tanzania.

The potential for patient dose reduction in diagnostic radiology was investigated in five major Tanzanian hospitals. The aim of this study was to follow up previously reported suggestions for improved practices to achieve dose reductions. The suggestions were implemented and entrance surface dose measurement repeated by using well-calibrated LiF thermoluminescence dosemeters. The results show that dose reductions in chest PA X ray examinations ranged from 15% to 50%. For abdomen AP and pelvis AP X ray examinations, the dose reductions ranged from 24% to 73% and from 25% to 72%, respectively. The respective dose reductions for lumbar spine AP and LAT projections ranged from 4% to 58% and from 16% to 77%. Interestingly, the majority of radiographs obtained after the implementation of dose reduction measures were useful for intended diagnosis according to the opinion of radiologists. It is concluded that significant dose reductions can be achieved in the country without loss of diagnostic information. Such dose reductions also predict reductions of radiation risk to patients.

Humans↗
PubMed2004

Colitis in patients with breast carcinoma treated with taxane-based chemotherapy.

BACKGROUND: Colitis is a rare but serious gastrointestinal complication associated with taxane-based chemotherapy in patients with cancer. The incidence, clinical presentation, and outcome of colitis in patients with breast carcinoma treated with taxane-based chemotherapy is not known. METHODS: The authors searched their electronic database and identified patients with breast carcinoma who were treated with taxane-based chemotherapy between January 1997 and December 1999. Patients diagnosed with colitis were identified and their presentation and clinical outcomes were analyzed. RESULTS: During the study period, 1350 patients received taxane-based chemotherapy. Sixty-four patients were admitted to The University of Texas M. D. Anderson Cancer Center (Houston, TX) (73 admissions) for gastrointestinal complications. Neutropenia and/or fever accounted for 56 of these admissions. Fourteen patients (16 admissions) were diagnosed with colitis. All had abdominal pain at median Day 6 of their chemotherapy cycle (range, 3-8 days), with or without other symptoms. Computed tomography scans of the abdomen and pelvis were abnormal for the 10 patients tested, whereas only 3 of the 9 patients who underwent radiographic abdominal series had abnormal findings. Two patients had a colonoscopy that confirmed the diagnosis of colitis. Blood cultures were positive in only 3 (20%) of 15 colitis events. All eight patients tested for Clostridium difficile toxin were negative. One patient died of sepsis. An autopsy subsequently revealed cecal ulceration. Two patients had bowel perforations requiring hemicolectomy. Colitis recurred in two patients after they resumed taxane-based chemotherapy without dose reduction. Dose reductions prevented the recurrence of colitis in seven patients. Treatment discontinuation of taxane-based chemotherapy also prevented disease recurrence. CONCLUSIONS: Acute abdominal pain in patients with breast carcinoma treated with taxane-based chemotherapy signaled a potentially fatal colitis, and warrants aggressive supportive care. Dose reduction or discontinuation of taxane-based chemotherapy may prevent the recurrence of colitis.

Antineoplastic Agents, Phytogenic↗
PubMed1994

Reduction of radiation doses in leg lengthening procedures by means of audit and computed tomography scanogram techniques.

Children with congenital bone dysplasias may benefit from leg lengthening procedures. Such procedures, by necessity, require frequent and regular imaging. It is necessary to minimize the total radiation dose to these patients, and particularly the dose to the gonads. In the present study the films of 13 patients who had completed leg lengthening procedures were reviewed. The number of films was assessed together with the use of appropriate gonad shielding. In a second part of the study, thermoluminescent dosemeter measurements of radiation doses to a phantom were made for both plain radiographs (with and without gonad protection) and computed tomography (CT) scanograms. The results show that audit plays an important role in assessing radiographic practice with respect to accurate placement of gonad protection and confirm that a significant dose reduction can be accomplished by careful use of this lead shielding. Dose reduction can also be achieved by using alternative radiographic techniques such as CT scanograms. Other techniques such as ultrasound or dual-energy X-ray absorptiometry are briefly discussed. These may play an important additional part in the reduction of total radiation dose to the patients.

Adolescent↗
PubMed2005

Reduction of eye lens radiation dose by orbital bismuth shielding in pediatric patients undergoing CT of the head: a Monte Carlo study.

Our aim in the study was to assess the eye lens dose reduction resulting from the use of radioprotective bismuth garments to shield the eyes of pediatric patients undergoing head CT. The Monte Carlo N-particle transport code and mathematical humanoid phantoms representing the average individual at different ages were used to determine eye lens dose reduction accomplished with bismuth shielding of the eye in the following simulated CT scans: (a) scanning of the orbits, (b) scanning of the whole head, and (c) 20 degrees angled scanning of the brain excluding the orbits. The effect of bismuth shielding on the eye lens dose was also investigated using an anthropomorphic phantom and thermoluminescence dosimetry (TLD). Eye lens dose reduction achieved by bismuth shielding was measured in 16 patients undergoing multiphase CT scanning of the head. The patient's scans were divided in the following: CT examinations where the eye globes were entirely included (n=5), partly included (n=6) and excluded (n=5) from the scanned region. The eye lens dose reduction depended mainly on the scan boundaries set by an operator. The average eye lens dose reduction determined by Monte Carlo simulation was 38.2%, 33.0% and <1% for CT scans of the orbits, whole head, and brain with an angled gantry, respectively. The difference between the Monte Carlo derived eye lens dose reduction factor values and corresponding values determined directly by using the anthropomorphic phantom head was found less than 5%. The mean eye lens dose reduction achieved by bismuth shielding in pediatric patients were 34%, 20% and <2% when eye globes were entirely included, partly included and excluded from the scanned region, respectively. A significant reduction in eye lens dose may be achieved by using superficial orbital bismuth shielding during pediatric head CT scans. However, bismuth garments should not be used in children when the eyes are excluded from the primarily exposed region.

Adolescent↗
PubMed1998

Phase I and pharmacokinetic trial of aminopterin in patients with refractory malignancies.

PURPOSE: Aminopterin (AMT) is a potent folate analog that is no longer in routine clinical use. Because of laboratory data that suggests improved metabolism of AMT versus methotrexate (MTX) in lymphoblasts, we developed a phase I trial to determine the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), and pharmacokinetic profile of AMT. PATIENTS AND METHODS: Twenty patients with refractory malignancies were treated. The starting dose of AMT was 2.5 mg/m2 every 12 hours for two doses weekly: the dose of AMT was decreased and leucovorin (LV) rescue was added after the DLT was observed. Pharmacokinetics were performed after both intravenous (i.v.) and oral AMT administration. RESULTS: Mucosal toxicity was dose-limiting and resulted in the need for a dose reduction (dose level 2: AMT 2 mg/m2 every 12 hours for two doses weekly) and, subsequently, the addition of scheduled LV rescue (dose level 3: AMT 2 mg/m2 every 12 hours for two doses followed by LV 5 mg/m2 orally every 12 hours for two doses, starting 24 hours after the second dose of AMT). The mean areas under the curve (AUC) for the i.v. (n = 14) and oral (n = 13) doses were 1.20 +/- 0.09 (SE) and 1.05 +/- 0.14 micromol x h/L respectively. The half-life was 3.64 +/- 0.28 hours and the oral bioavailability in 12 matched subjects was 83.5% +/- 8.3%. One patient with endometrial adenocarcinoma achieved a complete response (CR) and remains on therapy at 11+ months. Seven patients had stable disease (SD) for 8 weeks or greater, which included one patient with a metastatic nerve sheath tumor who was stable for 9 months. CONCLUSION: We conclude that AMT has good oral bioavailability and that, when given on a q12 hour x two weekly schedule, the MTD is 2 mg/m2 with delayed LV rescue.

Administration, Oral↗