Biomedical subjects

M Ricciardello

Publications and source records attributed to M Ricciardello.

4 recordsLinked to original sources

PubMed1998

Risk to patients from radiation associated with radiofrequency ablation for supraventricular tachycardia.

BACKGROUND: Radiofrequency ablation may be associated with prolonged fluoroscopy times. Previous studies have calculated radiation risks by measuring the radiation dose at a limited number (6) of body sites. This is an inherently inaccurate measure. Our study aimed to quantify more precisely patient-related radiation risks associated with radiofrequency ablation for supraventricular tachycardia. METHODS AND RESULTS: Nine female patients having radiofrequency ablation for supraventricular tachycardia were studied. The radiation dose was determined at 41 body sites in each patient with the use of thermoluminescent dosimeters and was correlated with that measured simultaneously with a Diamentor dose-area product meter. The estimated mean organ doses (mGy) per 60 minutes of fluoroscopy were: lungs 30.8; bone marrow 4.3; left breast 5.1; right breast 3. 5; and thyroid 2.4. From the average organ doses, the estimated mean total lifetime excess risk of a fatal malignancy was 294 per million cases (0.03%) per 60 minutes of fluoroscopy. The risk calculation from the Diamentor dose-area product and thermoluminescent dosimeters were similar, suggesting that radiation dose was measured accurately. The estimated risk of radiation-induced malignancy increased with increasing body mass index (P=0.03). CONCLUSIONS: Prolonged fluoroscopy during radiofrequency ablation may potentially cause a small increase in the lifetime risk of fatal malignancy, with lung malignancy being most likely. This risk is small only with the use of techniques and x-ray equipment optimized to keep radiation as low as possible. The risk is increased in obese patients.

Adult↗

PubMed1998

Evaluation of radiation dose and risk to the patient from coronary angiography.

BACKGROUND: Coronary angiography is a commonly performed diagnostic procedure with life saving benefits for the patient. However, because of its potential to deliver a high radiation dose, caution is warranted. AIM: The purpose of this study was to determine the effective dose to an average patient from coronary angiography, to estimate the associated radiation risk in terms of fatal malignancy, and to examine ways effective dose may be reduced. METHOD: The dose-area product data from 210 examinations was used to determine the effective dose to the average patient by means of a commercially available software programme. Subsequently, the effective dose was used to estimate radiation risk based on the population averaged probability coefficients given in ICRP 60 and contrasted against age-related risk coefficients from the NRPB. The components of effective dose and radiation risk were examined to identify the organs most at risk. RESULTS: The average effective dose was found to be 3.4 +/- 1.3 mSv. The risk of fatal malignancy was estimated as 170 per million cases, or around one in 6000. The average lung dose was 14.7 mSv, with the risk of fatal lung cancer estimated as 125 per million cases or one in 8000. CONCLUSIONS: The average effective dose in this study was less than half that of most other studies. The lung was identified as the critical organ and the estimated risk of fatal cancer amounted to an increase of 0.017% above the normal incidence for the general population. The study affirmed that using a reduced cine frame rate, low dose pulsed fluoroscopy, added copper filtration and a conscious effort to reduce screening time can significantly reduce patient dose.

Adult↗

PubMed1995

Radiation exposure to patient and operator during radiofrequency ablation for supraventricular tachycardia.

BACKGROUND: Radiofrequency (RF) ablation has become the primary method of treatment for supraventricular tachycardia and often requires prolonged fluoroscopy times. AIM: To quantitate radiation exposure to patient and operator during RF ablation for supraventricular tachycardia. METHODS: Thermoluminescent dosemeters were used to monitor radiation at seven sites. Positions were: patient's thyroid, left scapula, T9 vertebra, right scapula and L4-L5 vertebra and the operator's thyroid and left hand. Monitoring was performed during 22 procedures. Of the patients studied 10 (45%) had atrioventricular junctional re-entry tachycardia (AVJRT) and 12 (55%) had accessory pathway tachycardia. RESULTS: The median fluoroscopy times (minutes) and inter-quartile ranges were 46 (39-65) for AVJRT, 55 (52-60) for left free wall accessory pathway (LFW), 107 (89-140) for septal and 166 (128-176) for RFW pathways. The mean radiation doses (mGy) to the chest wall were 50 for AVJRT, 47 for LFW, 87 for septal and 151 for RFW pathways. The mean radiation to the chest wall of the patient per case was found to be 3.9 times that reported for diagnostic cardiac catheterisation and 1.5 times that reported for angioplasty. CONCLUSIONS: Radiofrequency ablation is associated with significant irradiation of the patient and operator. All precautions should be taken to decrease this exposure. If eye irradiation is assumed to be equal to that to the thyroid, more than 45 procedures per month by a single operator (using ceiling-suspended lead glass shielding) may result in exceeding the recommended dose limit to the eye.

Adult↗

PubMed1995

Assessment of fluoroscopic systems with a simple test object.

A non-invasive test protocol and simple to use test object (the Westmead test object) has been devised to evaluate image quality of the complete fluoroscopic system, including the grid, under automatic brightness control (ABC). The new protocol tests the overall fluoroscopic system rather than individual components such as the image intensifier (II) tube, using the kVp and dose rate as determined by the ABC. A radiographic absorber is required to simulate clinical conditions by giving patient equivalent scatter, beam quality and exit beam intensity. Twenty (20) cm of water was used as an absorber and compared to commonly used copper sheet. It was found that no single thickness of copper gave both patient equivalent beam hardness and patient equivalent absorption under ABC conditions. The two absorbers, 1 mm copper and 20 cm water, were also trialed with the new test object in a survey of 23 fluoroscopic systems using the ABC protocol. Results for two test object features, Threshold Contrast and Contrast-Detail (Low Contrast Resolution), indicated an increased spread in the results for the water absorber when compared to the copper absorber. Of 15 units having a 23 cm field size, 10 units gave better Contrast-Detail results using a copper rather than a water absorber, with 5 results equivocal. Similarly, ten (10) units gave better Threshold Contrast results with copper, while 4 units were equivocal and 1 unit gave a poorer result with copper absorber when compared to a water absorber. It is therefore concluded that the test object and protocol should be used with a patient equivalent absorber (such as 20 cms water) for acceptance tests. Good image quality discrimination between units can then be obtained by correlating x-ray input dose with test object results, such as is given using the Contrast-Detail feature under ABC conditions.

Evaluation Studies as Topic↗