Biomedical subjects

J Damilakis

Publications and source records attributed to J Damilakis.

At least 19 recordsLinked to original sources

PubMed2006

Occupational exposure in the electrophysiology laboratory: quantifying and minimizing radiation burden.

Fluoroscopically guided procedures in the electrophysiology room, such as radiofrequency catheter ablation and implantation of cardiac resynchronization devices, may result in high radiation exposure of electrophysiologists and assisting staff. Our aim was to provide accurate and applicable data on occupational doses to the electrophysiology laboratory personnel. We exposed fluoroscopically an anthropomorphic phantom at three projections common in electrophysiology studies. For each exposure, scattered radiation was measured at 182 sites of the cardiology room at four body levels. Effective dose values, eye lens, skin and gonadal doses to the laboratory staff were calculated. Our study has shown that a procedure requiring 40 min of fluoroscopy yields a maximum effective dose of 129 microSv and a maximum value of gonadal dose of 56.8 microSv to staff using a 0.35 mm lead-equivalent apron. A conservative estimate of the electrophysiologist's annual maximum permissible workload is 155 procedures. Staff effective dose values vary by a factor of 40 due to positioning during fluoroscopy and by a factor of 11 due to radiation protection equipment. Undercouch protective shields may reduce gonadal doses up to 98% and effective dose up to 25%. Consequently, radiation levels in the electrophysiology room are not negligible. Mitigation of occupational exposure is feasible through good fluoroscopy and working practices.

Electrophysiology↗

PubMed2006

Treatment of benign diseases with megavoltage X-ray beams: is there a risk for gonadal damage?

AIMS: To measure the testicular and ovarian doses and to assess the risk for gonadal damage to patients treated with megavoltage X-ray beams for benign diseases. MATERIALS AND METHODS: Radiation therapy of benign diseases was simulated on an anthropomorphic phantom with a 6MV photon beam. The gonadal dose was calculated during the irradiation of heterotopic ossification, liver and vertebra haemangiomas, bone cysts, Graves' ophthalmopathy and gynaecomastia. Dose measurements were carried out using thermoluminescent dosimeters. For the radiotherapy of heterotopic ossification, the effect of using lead blocks to spare lymphatic drainage on the gonadal dose was determined. RESULTS: The ovarian and testicular total doses were found to be 2.00-680 and 2.0-39.0 mGy, respectively, depending on the gonadal location in respect to the treatment volume. The introduction of blocks into the primary beam resulted in an increase in gonadal dose up to a factor of 1.7. The radiation-induced risk of hereditary disorders in future generations was (1.0-40.8) x 10(-4) and (1.0-23.4) x 10(-4) for women and men, respectively. CONCLUSIONS: Radiation therapy of benign diseases always resulted in gonadal doses below 1 Gy and therefore there was no risk for permanent gonadal failure. The excess risk of radiation-induced hereditary disorders in offspring was low in comparison with the natural frequency of these effects. However, there was a considerable excess in risk after irradiation in the hip bone.

Bone Cysts↗

PubMed2006

Experimental determination of the effect of detector size on profile measurements in narrow photon beams.

The aim of this work is to investigate experimentally the detector size effect on narrow beam profile measurements. Polymer gel and magnetic resonance imaging dosimetry was used for this purpose. Profile measurements (Pm(s)) of a 5 mm diameter 6 MV stereotactic beam were performed using polymer gels. Eight measurements of the profile of this narrow beam were performed using correspondingly eight different detector sizes. This was achieved using high spatial resolution (0.25 mm) two-dimensional measurements and eight different signal integration volumes A X A X slice thickness, simulating detectors of different size. "A" ranged from 0.25 to 7.5 mm, representing the detector size. The gel-derived profiles exhibited increased penumbra width with increasing detector size, for sizes >0.5 mm. By extrapolating the gel-derived profiles to zero detector size, the true profile (Pt) of the studied beam was derived. The same polymer gel data were also used to simulate a small-volume ion chamber profile measurement of the same beam, in terms of volume averaging. The comparison between these results and actual corresponding small-volume chamber profile measurements performed in this study, reveal that the penumbra broadening caused by both volume averaging and electron transport alterations (present in actual ion chamber profile measurements) is a lot more intense than that resulted by volume averaging effects alone (present in gel-derived profiles simulating ion chamber profile measurements). Therefore, not only the detector size, but also its composition and tissue equivalency is proved to be an important factor for correct narrow beam profile measurements. Additionally, the convolution kernels related to each detector size and to the air ion chamber were calculated using the corresponding profile measurements (Pm(s)), the gel-derived true profile (Pt), and convolution theory. The response kernels of any desired detector can be derived, allowing the elimination of the errors associated with narrow beam profile measurements.

Fourier Analysis↗

PubMed2005

The effectiveness of calcitonin on chronic back pain and daily activities in postmenopausal women with osteoporosis.

The aim of this study was to investigate the effect of nasal calcitonin on chronic back pain and disability attributed to osteoporosis. The study design involved three groups of osteoporotic postmenopausal women suffering from chronic back pain. Group I consisted of 40 women with vertebral fractures, group II of 30 women with degenerative disorders and group III of 40 patients with non specific chronic back pain and without abnormality on plain X-rays. Pain intensity was measured using a numerical rating scale (NRS) and disability due to back pain was measured using the Oswestry disability questionnaire. The patients were randomly assigned to receive, for three months, either 200 IU intranasal salmon calcitonin and 1,000 mg of oral calcium daily (groups IA, IIA, IIIA) or 1,000 mg of oral calcium daily (groups IB, IIB, IIIB). Repeated measures ANOVA showed that there were no significant time, group or interaction effects for pain intensity and disability in any of the groups studied. Mean Oswestry and NRS scores were reduced during the follow-up period in the groups IA, IIIA, but the differences between the two time points were not statistically significant. Intranasal calcitonin has no effect on chronic back pain intensity and functional capacity of osteoporotic women regardless of the presence of fractures, degenerative disorders or chronic back pain of non-specific etiology.

Activities of Daily Living↗

PubMed2005

Organ and effective dose conversion coefficients for radiographic examinations of the pediatric skull estimated by Monte Carlo methods.

The objective of the present work was to provide precise effective and organ dose data for radiographic examinations of the skull performed on pediatric patients. To accomplish this, the MCNP4C2 transport code was utilized and 18 mathematical anthropomorphic phantoms, representing ages from a newborn child to a 17-year-old adolescent, were developed. Three common projections, anterior-posterior, posterior-anterior and lateral, were considered. The results consist of effective and organ radiation doses normalized to the entrance surface dose. Normalized data are presented for a wide range of peak kilovoltages and beam filtration values so that doses for any X-ray unit can be calculated. Both organ and effective dose values showed an inverse correlation with age. Good agreement was observed between the normalized effective doses produced in this study and values derived from calculations based on the National Radiological Protection Board coefficients for specific mathematical phantoms representing 1-, 5-, 10- and 15-year-old children. In the present work, dose data for nine mathematical phantoms representing 0-, 1-, 2-, 3-, 4-, 5-, 6-, 9- and 14-year-old pediatric patients were provided for estimation of organ and effective doses delivered to pediatric patients from radiographic examinations of the skull.

Adolescent↗

PubMed2005

The effect of z overscanning on patient effective dose from multidetector helical computed tomography examinations.

z overscanning in multidetector (MD) helical CT scanning is prerequisite for the interpolation of acquired data required during image reconstruction and refers to the exposure of tissues beyond the boundaries of the volume to be imaged. The aim of the present study was to evaluate the effect of z overscanning on the patient effective dose from helical MD CT examinations. The Monte Carlo N-particle radiation transport code was employed in the current study to simulate CT exposure. The validity of the Monte Carlo simulation was verified by (a) a comparison of calculated and measured standard computed tomography dose index (CTDI) dosimetric data, and (b) a comparison of calculated and measured dose profiles along the z axis. CTDI was measured using a pencil ionization chamber and head and body CT phantoms. Dose profiles along the z axis were obtained using thermoluminescence dosimeters. A commercially available mathematical anthropomorphic phantom was used for the estimation of effective doses from four standard CT examinations, i.e., head and neck, chest, abdomen and pelvis, and trunk studies. Data for both axial and helical modes of operation were obtained. In the helical mode, z overscanning was taken into account. The calculated effective dose from a CT exposure was normalized to CTDI(free in air). The percentage differences in the normalized effective dose between contiguous axial and helical scans with pitch = 1, may reach 13.1%, 35.8%, 29.0%, and 21.5%, for head and neck, chest, abdomen and pelvis, and trunk studies, respectively. Given that the same kilovoltage and tube load per rotation were used in both axial and helical scans, the above differences may be attributed to z overscanning. For helical scans with pitch = 1, broader beam collimation is associated with increased z overscanning and consequently higher normalized effective dose value, when other scanning parameters are held constant. For a given beam collimation, the selection of a higher value of reconstructed image slice width increases the normalized effective dose. In conclusion, z overscanning may significantly affect the patient effective dose from CT examinations performed on MD CT scanners. Therefore, an estimation of the patient effective dose from MD helical CT examinations should always take into consideration the effect of z overscanning.

Computer Simulation↗

PubMed2004

Quantitative ultrasound measurements in children and adolescents with: type 1 diabetes.

The aim of the current study was to evaluate bone status at the radius and phalanx in children and adolescents with type 1 diabetes by using quantitative ultrasound (QUS) measurements. Thirty pediatric patients, 16 male and 14 female, with type 1 diabetes of duration of 5 to 177 months and mean (+/- SD) age 11.3 +/- 4.6 years were studied. QUS measurements were carried out using the Sunlight Omnisense 7000 S device. Speed of sound (SOS) was measured at the radius and tibia. Diabetic control was assessed by glycosylated hemoglobin (HbA(1c)) measurements. Male and female patients with type 1 diabetes did not have significantly different SOS or HbA(1c) values. SOS Z-scores at both the radius and tibia were negatively associated with duration of disease ( r = -0 41 and r = -0.37 for the radius and tibia respectively, P < 0.05 for both correlations). Seven of 15 patients with duration of disease of >6 years had diminished SOS, defined as Z-score of <-1, at either the radius or tibia. SOS measurements at the radius showed moderate correlation with SOS at the tibia ( r = 0.58, P < 0.00 l). There was no correlation between SOS and HbA(1c). In conclusion, SOS Z-scores at both the radius and tibia show a significant negative correlation with duration of insulin-dependent diabetes in children. No relation was found between SOS and metabolic control of young diabetic patients.

Adolescent↗

PubMed2004

Determination of dose-area product from panoramic radiography using a pencil ionization chamber: normalized data for the estimation of patient effective and organ doses.

The aims of the present study were (a) to investigate the potential of pencil ionization chamber to be used for the determination of dose-width product (DWP) and dose-area product (DAP) from panoramic radiographic exposures and (b) to provide data normalized to DAP for the determination of patient effective and gonadal dose from panoramic radiography performed in any laboratory. A pencil ionization chamber commonly used to measure CT dose index (CTDI) in CT scanners was employed to determine DWP for various combinations of panoramic exposure settings at the beam exit slit of a Cranex Tome panoramic x-ray unit (Soredex, Helsinki, Finland). DWP values were also measured using an array of thermoluminescence dosimeters. Reproducibility of the DWP measurement was tested. The effect of milliamperage and kilovoltage of panoramic exposures on DWP was investigated. DAP was estimated using the value of DWP measured using the pencil ionization chamber and the beam exit slit length measured using dosimetric film attached on the beam exit slit. A Rando anthropomorphic phantom appropriately loaded with thermoluminescent dosimeters (TLDs) was used to obtain organ dose and effective dose values from panoramic radiography. Reproducibility of DWP determination using the proposed method was better than 1.5%. DWP was found to be linearly related to milliamperage (r>0.999, p<0.001) and to kilovoltage raised in a power ranging from 2.18 to 2.55. DWP measured using the pencil chamber was found to be up to 11% higher than the corresponding values determined using TLD array. The panoramic exposure obtained with settings appropriate for the typical adult patient was found to result in 0.008 mSv patient effective dose, 0.0002 mGy gonadal dose, and 11.3 cGy cm2 DAP. The use of a pencil ionization chamber is proposed for the determination of DWP and DAP from panoramic radiographic exposures. Normalized data over DAP were provided for the determination of patient effective and gonadal dose from panoramic radiography.

Body Burden↗

PubMed2004

Therapeutic external irradiation in women of reproductive age: risk estimation of hereditary effects.

Exposure of women of childbearing age to ionizing radiation may result in induction of genetic disorders in future generations. This study aims to estimate the risk of hereditary effects attributable to therapeutic external irradiation in women. An anthropomorphic phantom was used to simulate radiotherapy in female patients and ovarian dose was measured for irradiation of brain, breast and lung cancer, and for treatment of Hodgkin's disease. These malignancies are among the most common tumours presenting in women of reproductive age. Dose measurements were undertaken using thermoluminescent dosemeters and all exposures were made with 6 MV X-ray beams. The dose to ovaries was found to be 2-3 cGy, 8-11 cGy and 11-15 cGy depending on the distance from the primary irradiation field during radiotherapy of brain, breast and lung cancer, respectively. The corresponding ovarian dose resulting from treatment of supradiaphragmatic and infradiaphragmatic Hodgkin's disease was 18-25 cGy and 128-356 cGy, respectively. A small excess risk of genetic diseases of (1-15) x 10(-4) was estimated for radiotherapy above the diaphragm. Pelvic irradiation resulted in an increased risk of hereditary effects of (77-214) x 10(-4).

Female↗

PubMed2004

Pegulated liposomal doxorubicin and cisplatin given concurrently with conventional radiotherapy: a phase I dose-escalation trial for patients with squamous cell carcinoma of head and neck and lung.

This is a phase I study of concurrent chemoradiation with pegulated liposomal doxorubicin (PLDH) and cisplatin for patients with squamous non-small cell lung cancer (NSCLC) and head and neck carcinoma (SCCHN). Nine patients with NSCLC and 9 with SCCHN were recruited in two phase I dose-escalation trials. The starting dose of PLDH was 7 mg/m2 once a week and was increased by 5 mg/m2 dose increments for every 3 patients. The standard dose of cisplatin was 20 mg/m2 once a week for 6.5-7 weeks of conventional external irradiation. The total tumor dose was 64 and 70 Gy for NSCLC and SCCHN patients respectively. The maximum tolerated dose of PLDH was 12 mg/m2 for the two cohorts of patients. Grade 3 mucositis was the dose limiting toxicity for NSCLC and SCCHN patients, at the 17 mg/m2 dose level. Three chemoradiation delays of 7 days were confirmed. The median time of follow-up was 17.9 months (range 3-36 months). Four patients died due to local-regional failure combined with distant metastases (3 patients) and pericardial effusion (1 patient). In total, there were 6/18 (33%) CRs (95% confidence interval, 11-55%), and 10/18 (55%), PRs (95% confidence interval, 32-78%). The recommended phase II PLDH dose combined to cisplatin and external irradiation is 12 mg/m2/week. The incorporation of PLDH in concomitant chemoradiation regimens for future treatment of squamous cell carcinoma of the lung and head and neck is warranted.

Adult↗

PubMed2003

Bilateral variation in radial bone speed of sound.

The aims of this study were to: (a) examine differences in speed of sound (SOS) between the right (SOS(R)) and left (SOS(L)) radius; (b) detect bone loss following proximal forearm fracture by SOS measurement at the radius; and (c) compare SOS(L) and bone mineral density (BMD) of one-third, mid-distal, ultra-distal and total region of the left radius. Two hundred eighty-seven Caucasian women (mean age 60.4+/-6.7 years) participated in this study. All subjects were right-handed. Twenty-seven women (mean age 63.6+/-8.0 years) had suffered a high-energy fracture of the right or left forearm. The SOS was assessed using a quantitative ultrasound device, whereas BMD was measured by dual energy X-ray absorptiometry (DXA). The SOS(R) was significantly higher than SOS(L) (4047.5+/-121.0 vs 4026.3+/-113.4 m/s; p<0.001). The contralateral absolute difference was 1.94% (95% confidence intervals: 1.73-2.15%). In women who had suffered a fracture of their right forearm, SOS(R) was not significantly higher than SOS(L )(3989.9+/-141.8 vs 3985.0+/-151.1 m/s), whereas the bilateral difference was reduced to 1.45%. In women with a previous fracture of the left forearm, SOS(R) was significantly higher than SOS(L) (4076.9+/-92.8 vs 3992.6+/-124.0 m/s; p<0.01) and the bilateral difference was increased to 2.61%. Of the 260 subjects without fracture, 155 had greater SOS in the right radius, 102 had greater SOS in the left radius and 3 patients had equal values of SOS in both bones. Calculated correlations between SOS and BMD were weak to moderate ( r=0.27-0.41; p<0.0001 for all comparisons). The SOS measurements should be performed on both radial bones. A high-energy forearm fracture results in a decrease in SOS measured at the radius. Radial-bone SOS measurements cannot predict forearm BMD.

Absorptiometry, Photon↗

PubMed2003

Can radial bone mineral density and quantitative ultrasound measurements reduce the number of women who need axial density skeletal assessment?

The purpose of this study was to investigate the clinical usefulness of forearm bone mineral density (BMD) and speed of sound (SOS) at the phalanx and radius as pre-selection tests to identify women with low BMD at the axial skeleton. BMD was measured by dual-energy X-ray absorptiometry (DXA) in the forearm, lumbar spine and femoral neck. SOS at the radius and phalanx was measured using a multisite quantitative ultrasound (QUS) device. Measurements were performed on 524 consecutive women referred for the assessment of BMD. Women with a T-score <-1 and T-score < or =-2.5 at either spine or femoral neck were identified, and T-score cut-off values for the forearm DXA and QUS variables were determined. Cut-off values for the forearm BMD estimated to detect normal women and those with T-score <-1 at the axial skeleton identified a total of 82% of subjects with 91% certainty. Cut-off values for the forearm BMD determined to detect women with T-score >-2.5 and those with osteoporosis allowed the identification of 62% of the study population with 90% certainty. Cut-off values for the phalangeal and radial SOS estimated to detect normal women and those with T-score <-1 at the axial skeleton identified a total of 49% and 1% of subjects, respectively. Cut-off values estimated for QUS variables to detect women with T-score >-2.5 and those with osteoporosis at the axial skeleton either failed to detect subjects with sufficient certainty (phalangeal SOS) or detected a negligible percentage of patients (radial SOS). In conclusion, forearm BMD may be used as a pre-selection test to identify women with low BMD at the axial skeleton, thus enabling reduction of the number of women who need axial BMD assessment. SOS of the phalanges and radius appears to have less value in the detection of the women with low axial BMD.

Absorptiometry, Photon↗

PubMed2003

Conceptus radiation dose assessment from fluoroscopically assisted surgical treatment of hip fractures.

Our aims in the present study were to (a) provide normalized dose data for the estimation of the conceptus dose from fluoroscopically assisted surgical treatment of hip fractures carried out during all trimesters of pregnancy and (b) estimate the conceptus radiation dose and risks associated with fluoroscopy during a typical treatment of hip fracture performed on a pregnant woman. Conceptus doses normalized to entrance surface dose (ESD) or dose area product (DAP) were obtained with the help of anthropomorphic phantoms simulating pregnancy in the three trimesters of gestation. ESD and conceptus dose measurements were carried out using thermoluminescent dosimeters. DAP to conceptus dose conversion factors were estimated for the first, second and third trimesters of gestation. Conceptus dose data normalized to ESD were also estimated to investigate whether these conversion factors may be used for procedures carried out in x-ray units not equipped with a DAP meter. Fluoroscopically assisted surgical treatments were performed in 18 women. The projections involved in these procedures are (a) posteroanterior (PA) and (b) lateral crosstable 45 degrees (LC). Radiation doses for a potential conceptus were estimated by using normalized dose data obtained in phantoms. The results consist of tabulated dose data normalized to DAP or ESD for the estimation of a conceptus dose. An important finding of this study was that the total DAP of a procedure, instead of the individual DAP values of each projection, could be used for the accurate estimation of the conceptus dose. Conceptus doses calculated using dose data normalized to ESD are about 23% higher compared to those estimated using data normalized to DAP. This discrepancy may be attributed to the contribution of scattering radiation from PA projection to ESD measurement of LC projection and vice versa. Therefore, dose data normalized to ESD do not provide accurate conceptus dose estimation. Doses normalized to DAP showed a dependence on (a) tube potential and (b) tube filtration. Data are provided to extent the doses normalized to DAP for the standard spectrum to other tube voltages and filtrations. The maximum dose for a potential conceptus was 0.425 mGy for a patient irradiated for 50 seconds during the PA projection and for 40 seconds during the LC projection. Although the total duration of fluoroscopy is usually less than 2 minutes during a typical procedure, screening time as long as 14 minutes has been reported in the literature for treatment of complex fractures. The relationship between conceptus dose and fluoroscopy time found in the current study showed that, in these cases, the radiation dose received by a conceptus may exceed 1 mGy. In conclusion, an accurate estimation of conceptus doses associated with fluoroscopically assisted surgical treatment of hip fractures can be made using the DAP normalized dose data provided in this study. Conceptus doses from a typical procedure is less than 1 mGy during all trimesters.

Dose-Response Relationship, Radiation↗

PubMed2003

Risk estimation of radiation-induced thyroid cancer from treatment of brain tumors in adults and children.

The purpose of this study was to estimate the risk of thyroid cancer induction attributable to brain radiation therapy in adult and pediatric patients. An anthropomorphic phantom was used to simulate treatment of brain tumors with two lateral opposed fields. Thyroid dose was measured using thermoluminescent dosimeters. Phantom measurements were performed for all possible field sizes that may be applied during brain radiotherapy in adults and children. The dependence of the thyroid dose on the distance from the irradiation field and on the presence of beam modifiers in the primary beam was investigated. All phantom exposures were generated with a 6 MV photon beam. Thyroid dose was found to vary from 9.6 to 89.4 cGy and from 8.0 to 194.0 cGy depending upon the field size used and the thyroid location in respect to the field edge for adults and children respectively. The excess relative risk of thyroid cancer induction for exposed children was estimated to be 0.6-14.9. The corresponding excess relative risk for adults was 0.1-1.1. The introduction of lead blocks or wedges into the primary beam may result in a considerable increase of the risk of thyroid cancer due to the increase of the thyroid dose. This study shows that brain radiotherapy during childhood may be associated with an increased risk of secondary thyroid cancer while the risk in adult patients is much smaller.

Adult↗

PubMed2002

Embryo/fetus radiation dose and risk from dual X-ray absorptiometry examinations.

The aim of the current study was to estimate the embryo/fetus radiation doses and risks associated with spinal and hip dual X-ray absorptiometry (DXA) scans performed on the pregnant mother. The results were compared with the embryo/fetus dose from a thoracolumbar radiograph and pelvic radiograph. Posteroanterior (PA) lumbar spine and proximal femur scans during the first, second and third trimesters were performed on a phantom simulating pregnancy at the three trimesters of gestation. All scans were carried out using a Hologic 1000/W pencil beam DXA unit. Moreover, embryo/fetus doses from a (a) thoracolumbar radiograph and (b) pelvic radiograph were estimated for all periods of gestation using the same phantom. Radiation doses were measured using thermoluminescent dosimeters. The dose reduction achievable by shielding the embryo/fetus with a protective apron during DXA scans was studied for all trimesters of gestation. The embryo/fetus doses during the first trimester were measured to be 1.7 mGy and 2.7 mGy for the PA spine and femur DXA scan, respectively, for an embryo/fetus located 8.5 cm from the anterior maternal surface. The risk of excess fatal cancer was 0.2 per million unborn children irradiated in utero for measurements of the spine and 0.3 per million unborn children for measurements of the femur. The embryo/fetus doses during the second and third trimesters were 2.7 mGy and 4.9 mGy respectively for the scans of the lumbar spine. The risk of childhood fatal cancer was 0.3 per million for the second trimester and 0.5 per million for the third trimester. The embryo/fetus radiation doses during the second and third trimesters were estimated as 1.4 mGy and 1.0 mGy respectively for the examinations of the proximal femur. The risk of childhood fatal cancer was 0.1 per million for both trimesters. The use of the apron resulted in a very small change in the dose absorbed by the embryo/fetus. The embryo/fetus dose associated with both DXA modes investigated in the current study is at least 700 times lower in comparison with embryo/fetus dose from a thoracolumbar or pelvic radiograph in all periods of gestation. In conclusion, the embryo/fetus dose in bone density measurements of spine and femur using pencil beam DXA is lower than the average daily natural background in the United States of 8 mGy. The health provider can decide whether a DXA scanning is beneficial to a pregnant woman, taking into account the potential radiation risks to the embryo/fetus presented in the current study.

Absorptiometry, Photon↗

PubMed2002

Peripheral primitive neuroectodermal tumour during pregnancy.

The case of a 25-year-old primipara in the second trimester of pregnancy, suffering from a peripheral primitive neuroectodermal tumour (pPNET) diagnosed by bone biopsy, is described. External irradiation was initially performed because of Jacksonian seizures due to a lesion in the right cerebral hemisphere. Appropriate shielding was used to reduce fetal exposure during brain radiotherapy. Caesarian delivery at the 27th week of gestation was performed because of tumour progression. The neonate had no evidence of disease and survived for 1 month. However, the placenta and ovaries showed metastases from the maternal pPNET. The patient died 14 months after initial diagnosis owing to the aggressiveness of the tumour, the rapid and extensive semination (bone marrow, lung, liver, craniospinal axis involvement) and the inability to adequately treat the patient with appropriate doses of chemotherapy.

Adult↗

PubMed2001

Conceptus radiation dose and risk from cardiac catheter ablation procedures.

BACKGROUND: The aim of the current study was to estimate the conceptus radiation dose and risk associated with fluoroscopic imaging during a catheter ablation procedure for supraventricular tachycardia performed on the expectant mother. METHODS AND RESULTS: Exposure parameters and fluoroscopy times for each projection of the cardiac ablation procedure performed in 20 female patients of childbearing age were recorded. Radiation doses for a potential conceptus were estimated by using dose data obtained in anthropomorphic phantoms simulating pregnancy at the first, second, and third trimesters. Dose measurements were carried out using thermoluminescent dosimeters. For a typical examination, the average radiation dose to the conceptus was <1 mGy in all periods of gestation. Average excess fatal cancer was 14.5/10(6) unborn children irradiated during the first postconception weeks. Corresponding values for the second and third trimesters were 30 and 55.7/10(6), respectively. The risk for hereditary effects in future generations was 1.5/10(6) cases for conceptus irradiation during the first postconception weeks. Corresponding values for the second and third trimesters were 3.0 and 5.6/10(6), respectively. Formulas and dose data are presented for estimating the conceptus risk from any technique and x-ray system used for catheter ablation procedures. CONCLUSIONS: A typical catheter ablation procedure results in a very small increase in risk of harmful effects to the conceptus. However, estimation of conceptus dose from catheter ablation procedures is always needed to assess the risk to the individual developing in utero.

Adult↗

PubMed2001

Accurate assessment of patient effective radiation dose and associated detriment risk from radiofrequency catheter ablation procedures.

BACKGROUND: Radiofrequency (RF) cardiac catheter ablation procedures may require extended fluoroscopic exposure resulting in elevated radiation risk. The aim of the present study was to accurately establish RF ablation radiation risk levels and to provide means for accurate patient risk estimation from studies performed in any electrophysiology laboratory. METHODS AND RESULTS: Fluoroscopy required during cardiac ablation was classified into 4 types identified by beam orientation and irradiated tissue: (1) posteroanterior exposure during catheter advancing from the groin to the heart, (2) posteroanterior heart exposure, (3) left anterior oblique heart exposure, and (4) right anterior oblique heart exposure. The duration of each exposure was monitored in 24 patients undergoing RF cardiac ablation. Dose per minute of fluoroscopy was measured at 15 organs/tissues for each projection with the use of anthropomorphic phantom and thermoluminescence dosimetry. The effective dose rate was 219, 144, 136, and 112 mu/min for groin-to-heart posteroanterior, posteroanterior, left anterior oblique, and right anterior oblique exposure, respectively. A typical ablation procedure results in a total effective dose of 8.3 mSv per hour of fluoroscopy. The average excess of fatal cancers was estimated to be 650 and 480 per million patients undergoing RF ablation requiring 1 hour of fluoroscopy for US and UK populations, respectively. The average risk for genetic defects was determined to be 1 per million births. CONCLUSIONS: Radiation risk from RF cardiac ablation is moderate compared with other complications, but it may highly exceed radiation risk from common radiological procedures. Efforts should be made toward minimization of patient radiation risk from RF ablation procedures.

Adult↗