Ανάπτυξη μεθόδου εκτίμησης της δόσης ασθενών από ακτινοσκοπικά καθοδηγούμενες επεμβατικές εξετάσεις με την εφαρμογή υπολογιστικών τεχνικών Monte Carlo

Στρατάκης, Ιωάννης Εμμ.

Χατζηδάκης, Αδάμ

Δαμηλάκης, Ιωάννης

Γκουρτσογιάννης, Νικόλαος

Aim: To investigate radiation dose and associated risks associated with fluoroscopically guided interventional (IR) procedures. Methods: A method for the calculation of organ and effective doses, normalized to dose– area product (DAP), were estimated for IR procedures with use of a Monte Carlo transport code and an adult mathematical phantom. Exposure parameters from consecutive patients were used to determine average examination parameters for biliary (PTB), and angioplasty interventions. Thermoluminescent dosimeters were used in an anthropomorphic phantom to verify Monte Carlo calculations. Radiation-induced cancer and genetic risks were estimated. To investigate doses imparted to IR personnel scattered air-kerma dose rates were measured for neck, waist, and gonad levels at various sites in the interventional radiology laboratory. Dose rate values were converted to dose-area product (DAP)–normalized airkerma values. In addition, sets of thermoluminescent dosimetry crystals were placed in both hands of the interventional radiologist to monitor doses. Results: The results consist of doses normalized to DAP so patient dose from any technique and x-ray unit can be easily calculated for left and right biliary drainage and/or stenting and for iliac and renal angioplasty procedures. The average effective dose varied from 1.8 to 5.4 mSv depending on biliary procedure approach (left vs right access) and procedure scheme. A maximum effective dose of 13 mSv was estimated for 30 minutes of fluoroscopy for PTB procedures. For iliac and renal angioplasty, the average effective dose varied from 15 to 24.5 mSv depending on procedure scheme and the sex of the patient. A good agreement was found between Monte Carlo–calculated data and data derived from thermoluminescent dosimetry. Isodose maps of DAP-normalized air-kerma doses in the interventional laboratory for projections commonly used in PTB procedures are presented. To facilitate effective dose estimation, normalized dosimetric data at the interventional radiologist’s position are presented for left and right access drainage procedures, metallic stent placement only, and drainage and metallic stent placement in one-session procedures with and without undercouch shielding. Doses to the hands of interventional radiologists are presented for left and right transhepatic biliary access and metallic stent placement. Conclusions: Radiation-induced cancer risk may be considerable for younger individuals undergoing transluminal angioplasty with stent placement. Doses delivered to patients undergoing PTB procedures are comparable to those that arise from computed tomography protocols. Radiation-induced cancer risk may be considerable for young patients undergoing PTB drainage and stent implantation procedures. Body level–specific normalized air-kerma distributions from commonly used projections in PTB procedures may be useful to accurately quantify dose, maximum workloads, and possible radiogenic risks delivered to medical personnel working in the interventional radiology laboratory. Normalized dose data presented will enable occupational exposure estimation from other institutions. Most PTA/stenting procedures can result in considerable radiation doses to the patient, even when performed with modern fluoroscopic equipment. Even higher radiation doses can be imparted due to multiple procedures, extended exposure times affected by the clinical condition of the patient and the level of experience of the interventional radiologist. Genetic risks were considered minimal. However, fatal cancer risks cannot be neglected especially for relatively young individuals. (EN)

Τύπος Εργασίας--Διδακτορικές διατριβές

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Μέθοδος Monte Carlo

Ακτινοβολίας δοσολογία

Radiometry

Radiation Dosage

Monte Carlo Method

Ακτινομετρία

Πανεπιστήμιο Κρήτης

E-Locus Ιδρυματικό Καταθετήριο

Elocus

Ελληνική γλώσσα

2007-07-26

http://elocus.lib.uoc.gr:443/dlib/4/4/d/metadata-dlib-23c2fceb46fb94939d61692f86a59ad1_1244102237.tkl

000346133

Σχολή/Τμήμα--Ιατρική Σχολή--Τμήμα Ιατρικής--Διδακτορικές διατριβές