Vpliv doze na ščitnico pri mamografiji : diplomsko delo

Polič, Martina (author), Vičar, Špela (author), Mekiš, Nejc (mentor), Izlakar, Jani (co-mentor)

Uvod: Mamografija je rentgensko slikanje dojk za zgodnje odkrivanje rakavih in drugih patoloških sprememb v tkivu dojke. Pri izvedbi te diagnostične preiskave je potrebno upoštevati načelo ALARA (As low as reasonably achievable), kar pomeni, da jo izvedemo ob čim nižji dozni obremenitvi žleznega tkiva dojke in okolnih kritičnih organov. Eden teh je žleza ščitnica, ki leži na prednji strani v spodnjem delu vratu in je zelo občutljiva na ionizirajoče sevanje, predvsem pri izpostavljenosti v mladosti. Namen: Namen diplomskega dela je ugotoviti kakšno dozo prejme ščitnica pri mamografiji in za koliko se le-ta zmanjša ob uporabi zaščite za ščitnico. Metode dela: Meritve smo izvedli na dveh mamografskih aparatih. Za simulacijo trupa preiskovanke smo uporabili fantom telesa z oznako PBU 60. Dojke smo simulirali s pleksi steklom v treh različnih debelinah (2-, 4,5-, 7 cm) in slikali v osnovni pravokotni (CC) projekciji z avtomatsko izbiro ekspozicijskih pogojev. Na vsakem aparatu smo opravili po 20 meritev za vsako debelino, od teh 10 z zaščito in 10 brez nje, skupno torej 60 meritev na enem aparatu. Dozo na ščitnico smo merili z dozimetrom Unfors EDD-30 in podatke zbrali s sprotnim zapisovanjem. Ti so bili izraženi v enoti mikro Gray (µGy), kar predstavlja absorbirano dozo. Meritve smo pomnožili s tkivnim utežnim faktorjem in dobili efektivno dozo, merjeno v sievertih (Sv). Rezultati: Na aparatu 1 so bile vrednosti v povprečju nižje kot na aparatu 2. Pri debelini 2 cm je ščitnica prejela najmanjšo dozo. Na aparatu 1 pri slikanju brez zaščite je ta znašala 0,188 µSv in 0,274 µSv na aparatu 2. Ob uporabi zaščite se je znižala za 91 do 95 %. Pri slikanju debeline 7 cm, brez uporabe zaščite, je ščitnica prejela največjo dozo (3,878 µSv na aparatu 1 in 4,764 µSv na aparatu 2). Ob uporabi zaščite pa se je ta zmanjšala za 98 %. Tudi pri debelini 4,5 cm se je doza ob uporabi zaščite zmanjšala, in sicer za 96 %. Razprava in zaključek: Hipotezi, ki smo si jih zastavili ob pričetku pisanja, lahko na podlagi pridobljenih rezultatov potrdimo, saj je z večanjem debeline pleksi stekla doza naraščala. Ob uporabi zaščite pa se je le-ta zmanjšala.

• Language: Slovenian
• Keywords: dojka, meritve doz, pleksi steklo, ščitnična zaščita
• Work type: Bachelor thesis/paper
• Organization: ZF - Faculty of Health Sciences
• Year: 2017
• PID: 20.500.12556/RUL-94567
• COBISS.SI-ID: 5337195
• Publication date in RUL: 05.09.2017

Secondary language

• Language: English
• Title: Effect of the radiation on the thyroid gland, due to a mammography : thesis

Abstract

Introduction: Mammography is an X-ray breast imaging for early detection of cancer and other pathological changes in breast tissue. By applying this diagnostic tests, it is necessary to take into account the principle of ALARA (As low as reasonably achievable), which means that it is carried out at the lowest possible radiation exposure of the glandular tissue of the breast and surrounding critical organs. One of these is the thyroid gland, which is located on the front of the lower part of the neck and is very sensitive to ionizing radiation, especially with exposure at a young age. Purpose: The purpose of the thesis is to determine what dose is received by the thyroid gland in mammography and how much it is reduced with the use of a thyroid gland protection. Methods: Measurements were performed on two mammographic devices. To simulate the torso of the participant, we used a phantom body, labelled PBU 60. Breasts were simulated with plexiglass in three different thicknesses (2-, 4.5-, 7 cm) and photographed in the basic rectangular (CC) projection with automatic selection of the aspect conditions. 20 measurements were carried out on each of the devices for every thickness, 10 of those with protection and 10 without it, for a total of 60 measurements on a single device. The dose to the thyroid was measured with the Unfors EDD-30 dosimeter and the data was collected with real-time writing. Data expressed in micro gray units (µGy), which represents the absorbed dose. Measurements were multiplied with the tissue weighting factor and we obtained an effective dose, measured in sieverts (Sv). Results: On device 1 the levels were on average lower than on device 2. With the 2 cm thickness, the thyroid gland received a minimum dose. On device 1, for imaging without protection, it amounted to 0,188 µSv and 0,274 µSv on device 2. When using protection it decreased by 91 to 95%. In the case of imaging with a 7 cm thickness, without the use of protection, the thyroid gland received the highest dose (3,878 µSv on device 1 and 4,764 µSv on device 2). By using protection, however, this decreased by 98 %. With the 4,5 cm thickness the dose was also reduced with the use protection, by 96 %. Discussion and conclusion: The hypotheses that we set at the beginning of writing, can be confirmed on the basis of the obtained results, as the dose increased by increasing the thickness of the plexiglass. By using protection, the dose was reduced.

• Keywords: breasts, dose measurement, plexiglass, thyroid protection