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PubMed1988

Re-irradiation of mouse skin: similarity of dose reductions for healing and macrocolony endpoints.

The amount of residual injury in mouse tail skin, assessed by the decrease in re-irradiation dose for equal effect, was similar whether assessed using healing or colony endpoints (17-21% after single priming doses). There were tendencies towards an increased sensitivity of the colony-forming cells by a factor of about 2, and less residual injury after multifractionated priming doses. These observations are compatible with a lower alpha/beta ratio characterising the response to dose fractionation for residual injury than for the acute healing response.

Animals↗
PubMed2002

Anthrax vaccine: immunogenicity and safety of a dose-reduction, route-change comparison study in humans.

Anthrax vaccine adsorbed (AVA), an effective countermeasure against anthrax, is administered as six subcutaneous (SQ) doses over 18 months. To optimize the vaccination schedule and route of administration, we performed a prospective pilot study comparing the use of fewer AVA doses administered intramuscularly (IM) or SQ with the current schedule and route. We enrolled 173 volunteers, randomized to seven groups, who were given AVA once IM or SQ; two doses, 2 or 4 weeks apart, IM or SQ; or six doses at 0, 2, 4 weeks and 6, 12, and 18 months (control group, licensed schedule and route). IM administration of AVA was associated with fewer injection site reactions than SQ administration. Following the first SQ dose of AVA, compared to males, females had a significantly higher rate of injection site reactions such as erythema, induration and subcutaneous nodules (P<0.001). Reaction rates decreased with a longer dose interval between the first two doses. The peak anti-PA IgG antibody response of subjects given two doses of AVA 4 weeks apart IM or SQ was comparable to that seen among subjects who received three doses of AVA at 2-week intervals. The IM route of administering this aluminum hydroxide adsorbed vaccine is safe and has comparable peak anti-PA IgG antibody levels when two doses are administered 4 weeks apart compared to the licensed initial dose schedule of three doses administered 2 weeks apart. A large pivotal study is being planned by the Centers for Disease Control and Prevention to confirm these results.

Adult↗
PubMed2002

CT colonography at different radiation dose levels: feasibility of dose reduction.

PURPOSE: To investigate the sensitivity and specificity of polyp detection and the image quality of computed tomographic (CT) colonography at different radiation dose levels and to study effective doses reported in literature on CT colonography. MATERIALS AND METHODS: CT colonography and colonoscopy were performed with 100 mAs in 50 consecutive patients at high risk for colorectal cancer; 50- and 30-mAs CT colonographic examinations were simulated with controlled addition of noise to raw transmission measurements. One radiologist randomly evaluated all original and simulated images for the presence of polyps and scored image quality. Differences in image quality were assessed with the Wilcoxon rank test. Scan protocols from the literature and recent (unpublished) updates were collected. RESULTS: In nine of 10 patients with polyps 5 mm in diameter or larger (sensitivity, 90%) and in seven of 17 patients with polyps smaller than 5 mm, polyps were correctly identified with CT colonography at all dose levels. Specificity for patients without polyps 5 mm or larger was 53%-60% at all dose levels and for patients without any polyps was 26% (at 100 and 50 mAs) and 48% (at 30 mAs). Image quality decreased significantly as the dose level decreased. The median effective doses (supine and prone positions) calculated from protocols reported in the literature and updates were 7.8 and 8.8 mSv, respectively. CONCLUSION: Although image quality decreases significantly at 30 mAs (3.6 mSv), polyp detection remains unimpaired. The median dose for CT colonography at institutions that perform CT colonographic research is currently 8.8 mSv.

Adult↗
PubMed1991

Design of a database with graphical analysis for X-ray quality assurance and dose information to assist in a programme for patient dose reduction.

A database system has been set up on an IBM PC to store X-ray quality assurance (QA) data and patient doses for all X-ray equipment operated by Grampian Health Board. Graphical analysis facilities have been developed to display data in a readily understandable form. Data on equipment specifications, QA test results, exposure factors for standard examinations, and thermoluminescent dosemeter (TLD) measurements of patient skin doses are stored in separate forms. X-ray machine outputs are fitted to a simple polynomial equation, and the data combined with information on exposure factors to calculate entrance doses for selected examinations. Data such as filtration and backscatter factors are derived from look-up tables for use in dose calculations. Histogram comparisons can be made between calculated doses, means of TLD measurements and National Radiological Protection Board reference levels to allow units giving high skin doses to be identified so that corrective actin can be taken.

Humans↗
PubMed2005

Radiation dose reduction to the male gonads during MDCT: the effectiveness of a lead shield.

OBJECTIVE: Our study was designed to quantify the effect of a standard gonad shield on the testicular radiation exposure due to scatter during routine abdominopelvic MDCT. SUBJECTS AND METHODS: Routine abdominopelvic MDCT was performed in 34 patients with gonadal lead shielding and 32 patients without this shielding; the testes were not exposed to the direct beam during the examination. We estimated the testicular dose administered with thermoluminescent dosimetry, taking into account each patient's body weight and body mass index (BMI). RESULTS: With a 1-mm lead shield, the mean testicular dose was reduced from 2.40 to 0.32 mSv, a reduction of 87%. The difference was found to be statistically significant (p < 0.0001). No correlation between testicular dose and body weight or BMI was found. CONCLUSION: Shielding the male gonads reduces the testicular radiation dose during abdominopelvic MDCT significantly and can be recommended for routine use.

Adult↗
PubMed1983

Dose reduction in pantomography of children by means of reduction of irradiated area.

An Orthopantomograph was provided with microswitches in order to reduce exposure time. The collimation was vertically reduced. The reduced field size obtained covered all dentoalveolar regions except the third molar areas. The dose of energy imparted was thus reduced from 1.6 to 0.6 mJ and thyroid gland dose from 0.13 to 0.04 mSv compared to complete pantomography. The economy in reduction of film size was 55%.

Child↗
PubMed2006

Patient dose reduction during voiding cystourethrography.

Voiding cystourethrography (VCUG) is a commonly performed examination in a pediatric uroradiology practice. This article contains suggestions on how the radiation dose to a child from VCUG can be made "as low as reasonably achievable" (ALARA). The pediatric radiologist should consider the appropriateness of the clinical indication before performing VCUG and utilize radiation exposure techniques and parameters during VCUG to reduce radiation exposure to a child. The medical physicist and fluoroscope manufacturer can also work together to optimize a pulsed-fluoroscopy unit and further reduce the radiation exposure. Laboratory and clinical research is necessary to investigate methods that reduce radiation exposures during VCUG, and current research is presented here.

Animals↗
PubMed2006

Dose reduction in CT while maintaining diagnostic confidence: diagnostic reference levels at routine head, chest, and abdominal CT--IAEA-coordinated research project.

PURPOSE: To measure radiation doses for computed tomography (CT) of the head, chest, and abdomen and compare them with the diagnostic reference levels, as part of the International Atomic Energy Agency Research coordination project. MATERIALS AND METHODS: The local ethics committees of all participating institutions approved the study protocol. Written informed consent was obtained from all patients. All scanners were helical single-section or multi-detector row CT systems. Six hundred thirty-three patients undergoing head (n = 97), chest (n = 243), or abdominal (n = 293) CT were included. Collected data included patient height, weight, sex, and age; tube voltage and tube current-time product settings; pitch; section thickness; number of sections; weighted or volumetric CT dose index; and dose-length product (DLP). The effective dose was also estimated and served as collective dose estimation data. RESULTS: Mean volumetric CT dose index and DLP values were below the European diagnostic reference levels: 39 mGy and 544 mGy . cm, respectively, at head CT; 9.3 mGy and 348 mGy . cm, respectively, at chest CT; and 10.4 mGy and 549 mGy . cm, respectively, at abdominal CT. Estimated effective doses were 1.2, 5.9, and 8.2 mSv, respectively. CONCLUSION: Comparison of CT results with diagnostic reference levels revealed the need for revisions, partly because the newer scanners have improved technology that facilitates lower patient doses.

Female↗
PubMed1979

Skin and gonadal dose reduction during hip radiography of the bull.

Radiology is being used to an increasing extent in the clinical diagnosis of hip lameness in bulls. Consequent gonadal doses may have important implications in later breeding programmes. Skin and gonadal doses were recorded during hip radiography of 18 bulls. An additional 0.13 mm copper filtration reduced skin dose by more than one third, but had no effect on gonadal dose. The average radiation dose to the gonads was approximately halved by completely surrounding the scrotum with lead sheeting 0.95 mm in thickness.

Animals↗
PubMed1990

Niobium filters for dose reduction in pediatric radiology.

The performance of a niobium filter, with K-edge at 19 keV, and a copper filter have been studied concerning absorbed dose, image quality and tube loading. Absorbed doses were measured with TLD. To evaluate image quality a perspex phantom with image quality test objects was used. In comparison with a conventional filter made of copper no significant advantage was obtained with the niobium filter.

Copper↗
PubMed2006

Cone beam CT with zonal filters for simultaneous dose reduction, improved target contrast and automated set-up in radiotherapy.

Cone beam CT (CBCT) using a zonal filter is introduced. The aims are reduced concomitant imaging dose to the patient, simultaneous control of body scatter for improved image quality in the tumour target zone and preserved set-up detail for radiotherapy. Aluminium transmission diaphragms added to the CBCT x-ray tube of the Elekta Synergytrade mark linear accelerator produced an unattenuated beam for a central "target zone" and a partially attenuated beam for an outer "set-up zone". Imaging doses and contrast noise ratios (CNR) were measured in a test phantom for transmission diaphragms 12 and 24 mm thick, for 5 and 10 cm long target zones. The effect on automatic registration of zonal CBCT to conventional CT was assessed relative to full-field and lead-collimated images of an anthropomorphic phantom. Doses along the axis of rotation were reduced by up to 50% in both target and set-up zones, and weighted dose (two thirds surface dose plus one third central dose) was reduced by 10-20% for a 10 cm long target zone. CNR increased by up to 15% in zonally filtered CBCT images compared to full-field images. Automatic image registration remained as robust as that with full-field images and was superior to CBCT coned down using lead-collimation. Zonal CBCT significantly reduces imaging dose and is expected to benefit radiotherapy through improved target contrast, required to assess target coverage, and wide-field edge detail, needed for robust automatic measurement of patient set-up error.

Equipment Design↗
PubMed1992

Dose reduction of hyoscine-N-butylbromide for double-contrast barium meal examinations--a prospective randomized study.

A search of the literature suggests that the conventional 20 mg dose of intravenous hyoscine-N-butylbromide (HBB) for smooth muscle relaxation in double-contrast barium meal (DCBM) studies is largely empirical. This study analysed the merits of three different doses (5 mg, 10 mg, 20 mg) in the performance of routine DCBMs. One hundred and twenty DCBM examinations were prospectively and randomly allocated to receive one of three doses. Three parameters were measured for each examination: gastroduodenal distension, delay in gastric emptying and gastric antrum overlapping with barium-filled duodenal loops. Almost half the examinations using 5 mg produced undesirable duodenal-gastric overlay. Unacceptable early flooding of the duodenal bulb with barium was seen mostly with doses of 5 mg and 10 mg. Overall, the best results were obtained with 20 mg. The continued use of 20 mg HBB in routine DCBMs is recommended.

Butylscopolammonium Bromide↗
PubMed2001

Dose reduction of steroid premedication for paclitaxel: no increase of hypersensitivity reactions.

BACKGROUND: Premedication with dexamethasone, ranitidine and clemastine is mandatory for patients receiving paclitaxel to avoid hypersensitivity reactions. The proposed dexamethasone dose is 20 mg orally 12 and 6 h prior to paclitaxel infusion. With this premedication severe hypersensitivity reactions are reduced to 1-2% of the treated patients. Besides this oral schedule a single dose of dexamethasone, 40 mg given i.v., just prior to paclitaxel has been shown to be equally effective. In an attempt to reduce steroid-induced side effects, especially for patients receiving weekly paclitaxel protocols, we reduced the dexamethasone dose. PATIENTS AND METHODS: A total of 132 patients were treated on an outpatient basis with paclitaxel-containing protocols. Paclitaxel was given in doses of 135-175 mg/m(2) once every 3 weeks in 76 patients and/or with 100 mg/m(2) weekly in 70 patients. Dexamethasone premedication was given in a single dose (40, 20, 10 mg) as an infusion directly before paclitaxel. RESULTS: 0/46 patients receiving 40 mg dexamethasone premedication in 235 cycles and 0/48 patients receiving 20 mg dexamethasone premedication in 186 cycles experienced a severe hypersensitivity reaction. 1/52 patients receiving 10 mg dexamethasone in 480 applications developed a severe hypersensitivity reaction with bronchospasm, hypotension and supraventricular tachycardia shortly after her first paclitaxel infusion started. CONCLUSION: No increase of severe hypersensitivity reactions is seen when dexamethasone premedication is reduced to doses of 20 or even 10 mg prior to paclitaxel infusion.

Adult↗