RADYASYON ve GEBELİK; X Ray Cihazları, MR, Nükleer Tıp ve Gebelik

Hamileler x ray cihazlarından geçebilir mi?

Havaalanları, kamu binaları ve alışveriş merkezlerinin girişindeki güvenlik kapıları radyasyon içermiyor.

Terör saldırıları, dünyanın her yerinde güvenlik önlemlerinin daha da sıkılaşmasına neden oluyor. Bu durum en çok hamile ve çocuklu kadınları etkiliyor. Hamileler havaalanlarında, alışveriş merkezlerinde ve resmi binaların girişlerindeki güvenlik cihazlarından geçmek istemiyor. Bu yüzden güvenlik görevlileriyle hamileler arasındaki tartışmalara sık sık tanık oluyoruz. Uzmanlarsa, yaygın ve yanlış inanışın aksine güvenlik cihazlarından geçmenin herhangi bir zararı olmadığını söylüyor. iletişim

KADIN ve HAMİLELERİN İÇİNİ RAHATLATACAK AÇIKLAMA; GÜVENLİK KAPILARINDAN GEÇİŞ

Hamile ve çocuklu kadınların güvenlik noktalarından rahatlıkla geçebilirler. İçinden geçtiğimiz kapı şeklindeki detektörlerin asla radyasyon içermediğini, bu nedenle bebeklere ya da rahim içindeki fetusa zarar vermeyeceğini söyleyebiliriz.

Bu cihazlar; çanta ve valizlerin geçtiği x ray cihazları ile metal kapı detektörleri olmak üzere genelde iki çeşittir.

Özellikle çekinilen ve içinden geçtiğimiz kapı şeklindeki bu detektörlerde metalik objeleri tespit edebilmek için düşük yoğunluklu manyetik alan kullanılır. Üzerinizde metal bir cisim varsa manyetik alanı kapatarak ötmeye başlar. Asla radyasyon içermez. Bu nedenle bebeklere ya da rahim içindeki fetuse zarar vermezler.

El tipi dedektörler de aynı mantıkla çalıştıklarından zararlı değildir.

EVDEKİ BUZDOLABINDAKİ MAGNET DAHA GÜÇLÜ

Bir buzdolabı mıknatısının manyetik alanı, içinden yürüyerek geçtiğimiz manyetik detektörden 10 kez, el tipi metal detektörden 600 kez daha güçlüdür.

Pek çok konuda olduğu gibi, kulaktan dolma yanlış bilgiler nedeniyle anne adayları bebeklerine bir zarar geleceği endişesiyle güvenlik noktalarından geçmek istemiyor.

Sanılanın aksine yüksek gerilim hattı altında oturmadıkça veya bazı radar, telsiz odaları gibi yüksek elektromanyetik alanların bulunduğu yerlerde çalışmadıkça, birçok manyetik cihaz, anne karnındaki bebeğe zarar vermiyor.

X RAY’DEN GEÇEN EŞYALARDA RADYASYON BİRİKMEZ

Havaalanı, emniyet ve kamu binalarında kullanılan x ray makinaları ise hastanelerde kullanılanlardan çok daha düşük -ölçülemeyecek kadar düşük- radyasyon yayar. Bunlar, büyük objelerin içindekileri daha detaylı görebilmek için değil, metal gibi göze çarpan şeyleri aramak için dizayn edilmiştir. Bu cihazlar etrafa radyasyon yaymazlar. Cihazın içinde yayılan radyasyon birikici değildir. Eşya kirliliğine yol açmaz. Cihazlarındaki radyasyon, onların içinden geçerken biberon, gıda, bitki, elektronik alet (cep telefonu) ya da ilaç olan ürünleri etkilemez.

Bir doz radyasyon microsievert olarak ifade edilir. Gelişmekte olan anne karnındaki bir bebeğe zarar vermek için 500 bin microsievert gereklidir. Geri saçılım ünitelerinde radyasyon yayılımı 1 microsievertden azdır. Bu da zarar verici dozdan çok uzaktır.
Bagajların geçtiği x ray makinaları, tıbbi x ray makinelerinden daha düşük ışın yayar.

Operatörün konumu çok iyi yalıtılmıştır ve kimseyi etkilemez. X ray makinasında görevli hamileler de güvenle çalışmaya devam edebilir. 

HERKES VE HAMİLELER İÇİN GÜVENLİDİR

Herhangi bir teknolojinin yayılmasından önce, kısa adı TSA olan Amerikan Ulaştırma Güvenlik İdaresi (The Transportation Security Administration) gebeleri de içeren tüm yolcuların güvenliğinden emin olmak için çok çeşitli testler yapar.

Amerikan Gıda ve İlaç Dairesi (FDA – U.S. Food and Drug Administration) radyolojik sağlık ve alet merkezinin yürüttüğü araştırmaya göre de bu makinalardan geçiş herkes ve hamileler için güvenlidir. Ayrıca, medikal bir neden olmaksızın insanların radyasyona mazur bırakılması yasalara aykırıdır.

Hava yolları ile uçak seyahatinde alınan radyasyon:

Kıtalar arası uzun bir uçuşta bile 40 haftalık bir gebelik boyunca izin verilen (1 mSV ya da 100 REM) kozmik radyasyon dozunun en çok %15 kadarını aldığımızdan uluslararası radyasyon komitesi çoğu gebeler için bu oranı ihmal edilebilir olarak değerlendirmiştir. Hava yolları personeli ve sık uçan yolcular için durum farklı olabilir…

Gebelikte diğer sorunlar için bkz

Radyasyon Röntgen Tomografi MRI ve Gebelikteki Riskler

Aşağıda tıbbi uygulamalarda sık kullanılan teşhis araçları ve gebeliğe etkileri ile ilgili derlediğim yurtdışı kaynaklardan alınmış (vakitsizlikten henüz çeviremediğim) ayrıntılı bilgiler içeren yazıyı ve tabloları bulacaksınız. Bununla birlikte nihai-son değerlendirmeyi doktorunuzla birlikte yapmanız hayati önem arzeder!!!

Radiation doses to the fetus for selected procedures are tabulated below. The doses are expressed in millirads. Unlike nuclear medicine studies, radiographic studies are subject to wide variablity in operator-dependent parameters.

These parameters include skin entrance dose (which depends upon KVP and MAS settings), beam filtration, tube output roentgens per minute), total fluroscopic “beam-on” time and the number and location of “spot” films taken. Because of the uncertainties in these parameters, these fetal dose values are considered to be approximations only. The parameter values used in caculating these doses are in part derived from U.S. national averages as compiled in NCRP Report 100, and in part from experience with actual Duke studies. Accordingly, these dose values should be used only as a guide to determining a subsequent course of action, and not as “hard and fast” numbers.

The fetal doses appear in colored cells. The colors reflect the degree of risk to the fetus associated with the study.

Procedures with “green” cells generally carry zero to minimal risk of harm. Studies with “yellow” cells incur doses for which the risk is possibly increased, but for which little supporting data is available. Studies with “red” cells can incur doses within the range of those associated with teratogenicity, mental retardation and secondary childhood cancers. For these studies, a more accurate dose reconstruction should be obtained.

RISK TO THE FETUS FROM IONIZING RADIATION

Ionizing radiation is known to cause harm in mammalian organisms. Deleterious effects of radiation include carcinogenicity, mutagenicity and organ system toxicity. As general rule, the sensitivity of a tissue to radiation is directly proportional to its rate of proliferation. Therefore, one could infer that the human fetus, because of its rapid progression from a single cell to a formed organism in nine months, is more sensitive to radiation than the adult. This inference is supported by the results of experiments in animal models, and experience with human populations that have been exposed to very high doses of radiation (atomic bombing victims). In humans, the major deleterious effects on the fetus include fetal wastage (miscarriage), teratogenicity (birth defects), mental retardation, intrauterine growth retardation and the induction of cancers (such as leukemia) that appear in childhood. Birth defects and mental retardation are the adverse effects which are of the most immediate concern for expectant mothers. Fortunately, not all exposures to ionizing radiation result in these outcomes. The risk to the fetus is a function of (a) gestational age at exposure and (b) the radiation dose.

At the level of most diagnostic procedures ( fetal dose < 10 rem), little data in humans is available. However, some qualitative observations regarding fetal risk can be made.

Radiation Risk Related to Gestational Age

Early Gestation / First Trimester — At this point, the rate of fetal growth is very rapid and the fetus, as an organism, is at its most radiation-sensitive stage if fetal demise is taken as an end-point. The incidence of fetal wastage consequential to radiation exposure at this stage of gestation is not known, since (a) many women were never aware they were pregnant at the time of the exposure or miscarriage, and (b) the “background” rate of miscarriage is believed to be high (25 – 50 percent of conceptions). It is believed that radiation injury during early gestation is an “all-or-nothing” effect.

Second Trimester — During this period, the overall growth rate of the fetus has slowed. However, the major organ systems are beginning to differentiate. From a standpoint of future development, the fetus is in its most sensitive stage. The incidence of gross congenital malformations and mental retardation are dose-related and appear to have thresholds; i.e. doses below which the incidence above “background” is not elevated.

Third Trimester — Irradiation during this period may deplete cell populations at very high doses (over 50 rem), but will not result in gross organ malformations.

Radiation Risk Related to Radiation Dose

1000 millirem = 1rem = 1 rad = 10 milliGray  = 10 mSv(millisievert) = 1.14 R(röntgen)

Bir yıl içinde doğal ortamda aldığımız bazal radyasyon yaklaşık 2,4 mSV /yıl (1-10) olup, tek bir Akciğer filmi 0,01 mSV, bir Akciğer BT(CT) ise görüntü kalitesine göre 1-5 mSV arasındadır.

The risk of deleterious effects increases with increasing dose. The nature of this dependence, i.e. the shapes of the dose-response curves for humans in the low-dose range (under 50 rem), is controversial. For some prenatal irradiation effects, there is epidemiological basis for the existence of threshold doses. For others, such as childhood cancer induction, the existence of a threshold is not clear-cut. Despite these uncertainties in the dose-effect relationship, some broad generalizations based on fetal dose ranges may be made.

Fetal Dose Less Than 1,000 millirem –– There is no evidence supporting the increased incidence of any deleterious developmental effects on the fetus at diagnostic doses within this range.

Fetal Dose between 1,000 millirem and 10,000 millirem — The additional risk of gross congenital malformations, mental retardation, intrauterine growth retardation and childhood cancer is believed to be low compared to to the baseline risk. However, the lower limits (in terms of statistical confidence intervals around the mean) for threshold doses for some studies, especially those related to cancer induction, fall within this range.

Fetal Dose Exceeding Than 10,000 millirem — The lower limits (in terms of statistical confidence intervals) for threshold doses for effects such as mental retardation and diminished IQ and school performance fall within this range. Overall, exposure at levels exceeding 10 rem could be expected to result in a dose-related increased risk for deleterious effects. For example, the lower limit (95% confidence interval) for the threshold for mental retardation is about 15 rem, which an expectation value of about 30 rem.

Counseling the Pregnant Patient Exposed to Ionizing Radiation

Due to the complexity of the issues surrounding fetal irradiation, there is no “standard” or predetermined advice that can be given to the expectant patient. However, it is possible to assist the patient in assessing the implications of the exposure if a systematic evaluation of the risk is performed. According to Dr. Robert Brent, the following parameters should be considered in the evaluation:

1. Gestational age at the time of exposure
2. Menstrual history
3. History of previous pregnancies, including a history of congenital malformations
4. Other potentially harmful environmental factors (malnutrition, smoking, alcohol / drugs, etc.)
5. Maternal / paternal age
6. Calculation of fetal exposure using dose reconstruction techniques
7. Attitude of the mother toward the pregnancy.

In any event, it is important not to defer medically necessary studies with anticipated fetal doses of less than 5,000 millirem based solely on a concern for causing adverse fetal effects.

FETAL RADIATION DOSES CONSEQUENTIAL TO SELECTED NUCLEAR MEDICINE PROCEDURES

The radiation doses to the fetus at various points in gestation for a number of diagnostic nuclear medicine studies are tabulated below. “Early” refers to irradiation during the first portion of the first trimester; “Months 3, 6 and 9” to irradiation at the ends of the first, second and third trimesters respectively. The doses are expressed in millirads, and assume an amount of administered radioactivity which is customary for the study. When an agent has several indications using different administered activities, the highest value is assumed.

Studies for which values appear in yellow cells can carry an increased risk. Please refer to the “Risks” page for more information.

The information supplied for I-131 sodium iodide and I-131 MIBG is for diagnostic studies. Therapeutic procedures with these radiopharmaceuticals incur far higher doses and require special computational treatment.

Acute radiation syndrome   If the figure next to the symptome is 1 or more, there’s a good chance the corresponding radiation dose could cause it. The data was taken from Wikipedia.

100.000 millirem ya da 100 rad iyonizan radyasyonda : Bulantı kusma halsizlik oluyor, Ölüm dozunun 8 de 1’i (0.125)

MR gebelikte güvenli mi? Are MRI scans safe during pregnancy? 

Özet: Kontrastlı (Gadolinyum) ve 1,5 Teslayı geçen MRI kullanımının gebelikteki güvenirliği şüpheli-önerilmez, üçüncü aydan sonra kontrast madde uygulanmadan 1,5 Tesla altında MR çekilmesi güvenli gözüküyor.  2016

Results of a cohort study of more than 1.4 million pregnancies show that magnetic resonance imaging (MRI) in the first trimester is safe but that gadolinium-enhance MRI at any time in pregnancy may slightly increase risk of a rare vision problem. Published in JAMA, the findings are from analysis of data in a Canadian universal health care database and the research may be the first controlled study of first-trimester in human pregnancy.

Using the database, births >20 weeks from 2003 to 2015 in Ontario, Canada were identified with the goal of evaluating the long-term safety after first-trimester exposure to MRI or exposure to gadolinium at any time during pregnancy. For the former, the authors looked at risk of stillbirth or neonatal death within 28 days of birth and any congenital anomaly, neoplasm, and hearing or vision loss from birth to age 4 years. For the latter, connective tissue skin disease that resembled nephrogenic systemic fibrosis (NSF-like) and a broader set of rheumatological, inflammatory, or infiltrative skin conditions were identified.

The overall rate of MRI was 3.97 per 1000 pregnancies. In pregnancies with no exposure to first-trimester MRI compared to those with exposure to the testing, the relative risk (RR) was 1.68 (95% CI, 0.97 to 2.90) for an adjusted risk difference of 4.7 per 1,000 person-years. (95% CI, -1.6 to 11.0). The risk was also not significantly higher for congenital anomalies, neoplasm or vision or hearing loss. The adjusted risk difference was 47.5 per 1000 pregnancies (95% CI, 9.7 to 138.2) for stillbirths and neonatal deaths in 7 MRI-exposed pregnancies versus the 9,844 unexposed pregnancies (adjusted RR, 3.70; 95% CI, 1.55 to 8.85).

For gadolinium versus no MRI, the hazard ratio for NSF-like outcomes was not statistically significant. The broader outcome of any rheumatological, inflammatory, or infiltrative skin condition occurred in 123 versus 384,180 births adjusted HR, 1.36; 95% CI, 1.09 to 1.69) for an adjusted risk difference of 45.3 per 1,000 person-years (95% CI, 11.3 to 86.8). When the investigators restricted MRI exposure to 5 to 10 weeks’ gestation, risk of congenital anomalies and hearing loss was unchanged but risk of vision loss was higher: adjusted HR 2.28 (95% CI, 1.09-4.77) or an adjusted risk difference of 2.7 per 1,000 person-years (95% CI, 0.2-7.9)

The authors noted that the study’s large size and population-based sample were strengths but that it was underpowered to assess uncommon outcomes in those exposed to first-trimester MRI. Risk of spontaneous or induced abortion before 21 weeks associated with MRI also is unknown because pregnancies that ended before 21 weeks were excluded.

Given their findings, the researchers said it may be wise to discuss with women who were advertently exposed to MRI in the first trimester or who are planning such exposure the “potentially slightly higher risk of vision loss” in offspring exposed during the first trimester. That risk, however, should be balanced against the finding that MRI exposure is not associated with a higher risk of other adverse outcomes. “It seems prudent,” they said, “to avoid more than 1.5-T MRI for pregnant women. Until further studies are done, these findings suggest that gadolinium contrast should be avoided during pregnancy.”

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