Estimation of radiation dose and risk to children undergoing cardiac catheterization for the treatment of a congenital heart disease using Monte Carlo simulations.

BACKGROUND: Children diagnosed with congenital heart disease often undergo cardiac catheterization for their treatment, which involves the use of ionizing radiation and therefore a risk of radiation-induced cancer. OBJECTIVE: The purpose of this study was to calculate the effective and equivalent organ doses (H(T)) in those children and estimate the risk of exposure-induced death. MATERIALS AND METHODS: Fifty-three children were divided into three groups: atrial septal defect (ASD), ventricular septal defect (VSD) and patent ductus arteriosus (PDA). In all procedures, the exposure conditions and the dose-area product meters readings were recorded for each individual acquisition. Monte Carlo simulations were run using the PCXMC 2.0 code and mathematical phantoms simulating a child's anatomy. The H(T) values to all irradiated organs and the resulting E and risk of exposure-induced death values were calculated. RESULTS: The average dose-area product values were, respectively, 40 ± 12 Gy·cm(2) for the ASD, 17.5 ± 0.7 Gy·cm(2) for the VSD and 9.5 ± 1 Gy·cm(2) for the PDA group. The average E values were 40 ± 12, 22 ± 2.5 and 17 ± 3.6 mSv for ASD, VSD and PDA groups, respectively. The respective estimated risk of exposure-induced death values per procedure were 0.109, 0.106 and 0.067%. CONCLUSION: Cardiac catheterizations in children involve a considerable risk for radiation-induced cancer that has to be further reduced.

Monte Carlo estimation of radiation doses in red bone marrow and breast in common pediatric x-ray examinations.

Radiation exposure was investigated for children undergoing various common radiographies in three dedicated pediatric hospitals in Greece. Kerma in air at the entrance of the beam (Ka,e) was measured with thermoluminescent dosimeters. Ka,e values ranged from 0.09 mGy to 5.52 mGy and were found to be greater in Hospital C, because of the increased high voltage and time-current product used by the radiation technologists. Equivalent doses in red bone marrow and breast were estimated with Monte Carlo simulation by PCXMC code. Values ranged from 2 microSv to 204 microSv for red bone marrow and from 0 to 817 muSv for breast. Variation in doses occurred due to field size, high voltage setting, and Ka,e.

Is sentinel node mapping useful in anorectal melanoma?

Anorectal melanoma (AM) is a rare disease and few guidelines have been established regarding its therapeutic management. Wide local excision, or less frequently, abdominoperineal resection is the treatment of choice. We present a female patient with an excised AM who was submitted to our Nuclear Medicine department for sentinel lymph node (SLN) mapping of the area. Under rigid proctoscopy the anal scar received four submucosal injections of technetium-99m-sulfur nanocolloid of 29.6 MBq each. Lymphoscintigraphy and intraoperative gamma-probe guided detection of the SLNs followed. SLNs were localized in the inguinal basins bilaterally and were negative on histology. A wide local excision followed the above test. Thirty months postoperatively the patient developed distant metastases, underwent radiotherapy and died six months later. Without changing prognosis sentinel lymph node detection, excision and histology were important in sparing the patient a futile inguinal lymph node dissection.

Radiation doses in common X-ray examinations carried out in two dedicated paediatric hospitals.

In this study, the entrance surface dose (ESD) and the respective effective dose (E) were determined for paediatric patients undergoing various common radiological examinations in two dedicated paediatric hospitals. Measurements of ESD were carried out in 289 examinations using thermoluminescent dosemeters. The patients were categorised according to their age and the mean ESD and E values were determined for each examination and age category. These ESD values were compared with the existing diagnostic reference levels (DRLs). In both hospitals there were cases where the DRLs were exceeded but in one of them this was rather the general rule, since additionally to the routine use of grid and low tube potential settings, occasional use of fluoroscopy for positioning check was also observed. While the remedial actions required to appropriately reduce the doses were clearly identified, this cannot be achieved without the cooperation of medical physicists with operators and radiologists.

Radiation dose considerations in common paediatric X-ray examinations.

BACKGROUND: For paediatric radiology, diagnostic reference levels (DRLs) have been proposed by the National Radiological Protection Board and the European Commission, representing a baseline above which re-evaluation of the equipment and the techniques used is necessary. OBJECTIVE: To measure the entrance surface dose (ESD) in various paediatric radiological examinations carried out at a large paediatric hospital in Greece and compare them with the existing DRLs. MATERIALS AND METHODS: Measurements of ESD using thermoluminescent dosemeters were carried out in a sample of 168 paediatric patients who underwent various common radiological examinations (chest, skull, pelvis, lumbar spine, full spine). The patients were categorised according to age, and the mean ESD was calculated for each examination and age category. Additionally, the effective doses were estimated from measured ESD using appropriate conversion coefficients found in the literature. RESULTS: The mean ESD values were found to be well below the proposed DRLs for all the examinations studied except for the chest, owing to the low tube potential used and tube filtration. CONCLUSIONS: Even in examinations that did not exceed the DRL, patient protection can be optimised further by appropriate collimation of field size to that necessary for diagnosis.