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PubMed2001

Dose reduction by direct-digital cephalometric radiography.

Patient radiation exposure was determined for conventional and direct-digital cephalometric radiography. An anthropomorphic phantom was positioned to expose lateral cephalographs from the patient's left side. The conventional radiographs were exposed with a Siemens Orthophos C unit (77 kV, 14 mA, 0.5 s) and a film-screen system of a relative speed of 400. The direct-digital radiographs were exposed with a Siemens Orthophos DS Ceph (73 kV, 15 mA, 15.8 s). A set of 108 thermoluminescence detectors (TLDs; Bicron STI/Harshaw, Solon, Ohio) was used for dose measurements. For each measurement, 84 TLDs were placed at the surface of the head and neck, as well as inside the phantom, at anatomically relevant positions. The remaining detectors were employed for calibration purposes and quality control. The highest absorbed doses were recorded for the conventional technique at the skin of the left parotid region (132 microGy), in the left parotid gland (103 microGy), and in the ocular lens of the left eye (81 microGy). Digital cephalometry resulted in an absorbed dose about 2 times lower than the dose received by the conventional technique. The effective doses had the same relation (conventional 2.3 microSv; digital 1.1 microSv). The results demonstrate that direct-digital cephalometric radiography cuts the patient's dose in half compared with the conventional screen-film technique. Direct-digital cephalometry is more advantageous than the conventional technique from the perspective of radiation protection.

Cephalometry↗
PubMed2006

The use of pharmacokinetically guided indinavir dose reductions in the management of indinavir-associated renal toxicity.

OBJECTIVES: Indinavir is associated with nephrotoxicity. Therapeutic drug monitoring of indinavir improves clinical outcome, but there is little data regarding therapeutic drug monitoring for patients with established indinavir-associated renal impairment. We prospectively studied the use of therapeutic drug monitoring in patients with virological success but established nephrotoxicity on an indinavir-containing regimen. METHODS: We measured indinavir C(trough)/C(2h), serum creatinine, pyuria, blood pressure (BP), weight and HIV RNA. The major endpoint of interest was the number of patients achieving a normal creatinine level 20 weeks following final indinavir dose adjustment. Primary analysis was by intention to treat (ITT). RESULTS: A total of 35 patients were enrolled; mean (SD) age 40.3 (5.8) years; mean (SD) BMI 21.5 (2.8) kg/m(2). At baseline 6/35 (17%) had a serum creatinine concentration within normal limits, but were offered enrolment because of previous nephrotoxicity (nephrolithiasis and/or abnormal serum creatinine), and a screening pharmacokinetic profile associated with increased nephrotoxicity risk. By ITT analysis 11/35 (31%) had normal creatinine at study end (P = 0.18). Of the 29 patients with abnormal creatinine at baseline, 7/29 (24.1%) had normal creatinine at study end (P = 0.016). Patients had a median (IQR) indinavir per dose adjustment over the study of 400 (400-800) mg. We observed improvements in estimated creatinine clearance, pyuria, resting BP and indinavir pharmacokinetic profile. HIV RNA control was maintained with continued immune recovery despite lower indinavir doses. CONCLUSIONS: Patients experiencing nephrotoxicity on an indinavir-containing regimen were safely maintained on indinavir by means of therapeutic drug monitoring. Parameters of renal function improved but did not return to baseline values, at least in the short-term.

Adult↗
PubMed2002

Radiation dose-reduction techniques in North American dental schools.

OBJECTIVE: The purpose of this investigation was to describe the extent to which dental schools use materials, equipment, and quality-assurance protocols that reduce radiation exposure to patients. STUDY DESIGN: Questionnaires soliciting information regarding intraoral and extraoral radiographic practices and quality-assurance procedures were sent to the directors of oral and maxillofacial radiology (OMR) at the 65 schools of dentistry in the United States and Canada. RESULTS: The response rate was 100%. E-speed film is used at 86% of institutions. Direct digital radiography is used at 58% of institutions for intraoral imaging and 11% for extraoral radiography. Other dose-reducing techniques include long source-film distances (88%), rectangular beam limitation (47%), leaded aprons (95% for extraoral films; 85% with thyroid collars for intraoral films), and rare earth intensifying screens (100%). The most commonly used tube potential is 70 kVp (88%). The director of OMR is solely responsible for radiographic policies at approximately 75% of institutions. Regular tests for film fog, speed, and contrast are done at roughly 75% of schools, while over 90% test darkroom lighting and x-ray equipment. CONCLUSIONS: Some dose-reducing strategies are commonly used in dental schools, while others have not gained wide acceptance.

Canada↗
PubMed2006

Can dose reduction to one parotid gland prevent xerostomia?--A feasibility study for locally advanced head and neck cancer patients treated with intensity-modulated radiotherapy.

AIMS: Dryness of the mouth is one of the most distressing chronic toxicities of radiation therapy in head and neck cancers. In this study, parotid function was assessed in patients with locally advanced head and neck cancers undergoing intensity-modulated radiotherapy (IMRT) with or without chemotherapy. Parotid function was assessed with the help of a questionnaire and parotid scintigraphy, especially with regards to unilateral sparing of the parotid gland. MATERIALS AND METHODS: In total, 19 patients were treated with compensator-based IMRT between February 2003 and March 2004. The dose to the clinical target volume ranged between 66 and 70 Gy in 30-35 fractions to 95% of the isodose volume. Ipsilateral high-risk neck nodes received an average dose of 60 Gy and the contralateral low-risk neck received a dose of 54-56 Gy. Eight of 19 patients also received concomitant chemotherapy. RESULTS: Subjective toxicity to the parotid glands was assessed with the help of a questionnaire at 0, 3 and 6 months and objective toxicity was assessed with parotid scintigraphy at 0 and 3 months. The mean dose to the ipsilateral parotid gland ranged from 19.5 to 52.8 Gy (mean 33.14 Gy) and the mean dose to the contralateral gland was 11.1-46.6 Gy (mean 26.85 Gy). At a median follow-up of 13 months, 9/19 patients had no symptoms of dryness of the mouth (grade I), 8/19 had mild dryness of the mouth (grade II) and only 2/19 had grade III xerostomia, although the parotid gland could only be spared on one side in most of the patients. CONCLUSIONS: Minimising the radiation dose to one of the parotid glands with the help of IMRT in patients with advanced head and neck cancers can prevent xerostomia in most patients and parotid scintigraphy is a useful method of documenting xerostomia.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

Radiation dose reduction in the evaluation of scoliosis: an application of digital radiography.

This report documents the clinical testing of scanning beam digital radiography as an imaging method in patients with scoliosis. This type of digital imaging requires a skin exposure of only 2.4 mR (0.619 microC/kg) per image, compared with the lowest possible posteroanterior screen-film exposure of 10 mR (2.58 microC/kg) at the chest and 60 mR (15.48 microC/kg) at the lumbar spine. Digital radiographic and screen-film images were obtained on multiple test objects and 273 patients. Scoliosis measurements using screen-film radiographs and digital radiographs were comparable to within a mean difference of 1 degrees at many different degrees of severity. The low-dose digital images were found to be useful and accurate for the detection and measurement of scoliosis after the first screen-film radiographs have excluded tumors and structural abnormalities.

Adolescent↗
PubMed2007

Circle of Willis at CT angiography: dose reduction and image quality--reducing tube voltage and increasing tube current settings.

PURPOSE: To prospectively assess the effects of lower tube voltage and various effective tube currents on image quality for computed tomographic (CT) angiography of the circle of Willis. MATERIALS AND METHODS: Institutional review board approval was obtained. Patients or family provided written informed consent. Signal-to-noise ratios (SNRs) were determined in a head phantom for various effective tube currents with tube voltages of 90, 120, and 140 kVp. Patients were referred for CT angiography because of acute subarachnoid hemorrhage (n = 20) or family history of cerebral aneurysms (n = 20). In each group, 10 patients were scanned with 120 kVp and 200 mAs(eff) and 10 were scanned with 90 kVp and 330 mAs(eff) (CT dose index volumes, 27.2 mGy and 20.6 mGy, respectively). CT numbers were measured in the internal carotid artery at the T junction and compared with a t test. Two radiologists used a five-point scale to subjectively score arterial enhancement, depiction of small arterial detail, image noise, venous contamination, and interference of subarachnoid blood. Mann-Whitney U test was used for statistical analysis. RESULTS: In the phantom, SNR(2) was proportional to effective tube current and CT dose index volume. With an identical effective tube current, SNR(2) was lower at 90 kVp than at 120 or 140 kVp. With identical CT dose index volume, tube voltage of 90 kVp resulted in a 45%-52% increase of SNR(2) compared with SNR(2) at 120 kVp. In patients, mean attenuation in the internal carotid artery T junction was higher with 90 kVp (340 HU) than with 120 kVp (252 HU, P < .001). Although dose at 90 kVp was 30% lower than dose at 120 kVp, scores for arterial enhancement and depiction of small arterial detail were higher at 90 kVp than at 120 kVp (4.0 vs 3.2 and 3.6 vs 3.1, respectively; P < .005). CONCLUSION: In head phantoms, lower tube voltage improved SNR at equal radiation doses. For CT angiography of the circle of Willis, this translated into superior image quality at 90 kVp.

Adult↗
PubMed2006

[Radiochemotherapy of cervical carcinoma. (Necessity of dose reduction in chemotherapy)].

INTRODUCTION: The concurrent radiochemotherapy used in the treatment of high risk and locally advanced cervical cancer therapy seems to be standard practice. Studies carried out in 1999 and 2000, reported the results of five large-scale prospective randomized investigations using radiotherapy which showed progression-free and overall survival rate increase compared to use of solely radiotherapy (Gynecology Oncology Group (GOG) 123, South West Oncology Group (SWOG) 8797, Radiotherapy Oncology Group (RTOG) 9001, Gynecology Oncology Group (GOG) 85, Gynecology Oncology Group (GOG) 120). OBJECTIVES: The aim of the investigation was to report our early findings of cervical cancer radiotherapy detailing the arising radiogen toxicity. METHOD: This is a report of a study carried out at the Oncoradiology Centre of Budapest, (between July 2002 and March 2005) on 66 cervical cancer patients. In concurrent radiotherapy the total dose of high photon energy percutaneous radiotherapy (megavolt therapy) for the pelvic region was 50.4 Gy, in 1.8 Gy fractions and with the weekly dosage of 40 mg/m2 cisplatin prior to the radiotherapy. RESULTS: The planned cytostatic treatment could be carried out on 27 patients (41%) on five treatments. At the same time, the number of treatments on the other patients had to be reduced due to haematological toxicity in the following way: 4 treatments on 16 patients (24%), 3 treatments on 7 patients (11%), 2 treatments on 10 patients (15%) and once on 6 patients (9%). Altogether it was necessary to reduce the dosage from the planned protocol, on 44 patients (67%). The optimal radiotherapy time of 56 days as reported in the literature, was exceeded in 17 cases (26%) on account of the radiogen toxicity. CONCLUSIONS: On the basis of our own results it is not advisable to raise the cisplatin weekly dosage to above 20 mg/m2.

Adult↗
PubMed2002

The use of radiation dose-reduction techniques in the practices of dental faculty members.

X-ray exposure to dental patients has been significantly reduced by the introduction of speed group E intraoral film, rectangular beam limitation, long position indicating devices (PIDs), and rare-earth intensifying screens for extraoral radiography. Research indicates that many dentists do not use these techniques. However, schools of dentistry have implemented them to varying degrees for many years, so this investigation was conducted to determine the extent to which dental school faculty members use these materials and techniques in their own practices. Comparisons were made between full- and part-time instructors, those in practice for fifteen years or less and those in practice for more than fifteen years, and those with postgraduate education versus those with no formal education beyond dental school. The significance of differences was measured with chi-square analysis. The results indicate that dentists with faculty appointments utilize dose-reducing techniques to degrees that are comparable to or greater than reported usage by non-dental faculty practitioners. Faculty dentists in practice fifteen years or less are more likely than their older colleagues to use E-speed film (p = 0.001), whereas those in practice more than fifteen years are more likely to use longer PIDs (p = 0.049). Greater acceptance of these practices by faculty may lead to reinforcement of their use in the clinical education of dental students.

Attitude of Health Personnel↗
PubMed2005

Initiation, dose reduction, and duration of inhaled corticosteroid therapy.

Asthma is characterized by persistent airway inflammation, which is associated with airway hyperresponsiveness and variable airflow obstruction, which accounts for the majority of symptoms experienced by asthmatic patients. Allergen sensitization and inhalation causes airway inflammation, and is likely important in the initiation and persistence of asthma in more than 50% of patients, and while allergen avoidance (or avoidance of other initiating factors, such as occupational sensitizers) can help some patients, it is often difficult to achieve. For this reason, pharmacologic treatment to reduce airway inflammation is currently the cornerstone of therapy for most individuals who have asthma.

Administration, Inhalation↗
PubMed2000

Equivalent asthma control after dose reduction with HFA-134a beclomethasone solution aerosol. Comparative Inhaled Steroid Investigation Group (CISIG).

AIM: The replacement of chlorofluorocarbon (CFC) by hydrofluoroalkane has the potential to improve airway deposition of BDP. We investigated whether HFA-BDP extra-fine solution aerosol 400 microg day(-1) is as effective as CFC-BDP 1000 micro day(-1) in patients with stable, moderate asthma, having persistent bronchial hyperresponsiveness. PATIENTS AND METHODS: One hundred and fifty patients with moderate asthma from 20 centres, on inhaled steroids for < or = 3 months, entered a 4-week run-in period with 1000 microg day(-1) CFC-BDP. Patients were then allocated to a 10-week study phase, receiving CFC-BDP 1000 microg day(-1) or HFA-BDP 400 microg day(-1). Symptom score and PEF were measured daily and recorded as biweekly means. Spirometry, PC20FEV1, blood eosinophils and serum ECP were determined on days 15, 29, 43 and 71, and compared to the last visit of the run-in period. All group members were trained in a quality control centre. RESULTS: Treating the population of the HFA-BDP group (n = 72) and the CFC-BDP group (n = 78) did not show significant differences in terms of symptoms, lung function, airway hyperresponsiveness and serum markers of inflammation at the end of the run-in period and the end of the study phase. CONCLUSION: Using HFA instead of a CFC metered dose inhaler, containing less than half the daily dose of BDP, allows control of symptoms and lung function parameters, without changes in bronchial hyperresponsiveness.

Administration, Inhalation↗
PubMedDate not supplied

Unenhanced helical CT using increased pitch for suspected renal colic: an effective technique for radiation dose reduction?

PURPOSE: To determine the accuracy and utility of unenhanced helical CT for suspected renal colic, using a pitch of either 2.5 or 3.0. METHODS: 59 consecutive patients underwent unenhanced helical CT. 5 mm contiguous images were obtained at a kVP of 120 and an mA of 260. Thirty-four patients were imaged at a pitch of 2.5, and 25 patients were imaged at a pitch of 3.0. Two radiologists, an attending (reader 1), and a second-year resident (reader 2), independently and retrospectively reviewed the CT images, blinded to the clinical outcome. The presence or absence of a ureteral stone was recorded and image quality was graded. A third radiologist determined accuracy for each reader. Average entrance exposure was estimated using a CT phantom at a variety of pitches. RESULTS: Overall sensitivity, specificity, and accuracy for reader 1 were 91, 96, and 93%. For reader 2, they were 86, 93, and 90%. There was no significant difference in accuracy using a pitch of 3.0 compared with 2.5 for either reader. Readers 1 and 2 rated image quality at 2.5 pitch as excellent for 88 and 76% of scans, respectively; at 3.0 pitch the scans were rated by both readers as excellent for 40% and acceptable for 60%. Average entrance exposures were estimated at 461, 553. and 913 mR at pitches of 3.0, 2.5, and 1.5. CONCLUSION: Increasing the pitch on unenhanced helical CT for suspected renal colic to 2.5 or 3.0 appears to be an effective method of reducing radiation dose. Although accuracy of the technique did not significantly change using a pitch of 3.0 in one group of patients, compared with a pitch of 2.5 in another group of patients, image quality did decrease.

Adult↗
PubMed2000

Dose reduction in gastrointestinal and genitourinary fluoroscopy: use of grid-controlled pulsed fluoroscopy.

OBJECTIVE: We evaluated the diagnostic accuracy of a grid-controlled fluoroscopy unit compared with a conventional continuous fluoroscopy unit for a variety of abdominal and pelvic fluoroscopic examinations. SUBJECTS AND METHODS: Seventy patients (29 men and 41 women; age range, 24-78 years) were enrolled in one of seven abdominal and pelvic fluoroscopic examinations, including upper gastrointestinal series (n = 20), barium enema (n = 10), voiding cystourethrogram (n = 10), percutaneous abdominal catheter tube injection (n = 10), hysterosalpingogram (n = 10), and percutaneous needle insertion and catheter placement (nephrostomy, percutaneous biliary drainage) (n = 10). Each patient underwent at least 10 sec of continuous fluoroscopy that was randomly and blindly compared with 10-sec periods of pulsed fluoroscopy at 15, 7.5, and 3.75 frames per second. A radiologist outside the examination room, unaware of the frame rate per second, evaluated the procedure in real time on a television monitor. The radiologist assessed image quality and diagnostic acceptability using a scoring system. Statistical analysis was performed using the paired Student's t test. RESULTS: For all procedures at all frame rates, we found no statistically significant superiority of one frame rate over another. For most procedures, the slower frame rates were considered equivalent to continuous fluoroscopy when the images were assessed for image quality and diagnostic confidence. CONCLUSION: Our findings suggest that most abdominal and pelvic fluoroscopic procedures can be performed at substantially lower frame rates than those used for continuous fluoroscopy; adopting this procedure may lead to substantial dose savings for the patient and the fluoroscopy operator.

Adult↗