Conceptus Dose Research Articles

Management of occupational exposure for pregnant employee in diagnostic radiology

Occupational exposure to ionizing radiation can occur in a range of industries, medical institutions, educational and research establishments. Most radiation protection programs, regulations and guidance apply specific restrictions to the occupational exposure of pregnant workers. Both worker and the employer carry responsibility towards safety. The pregnant worker and her conceptus are best protected in a facility that uses best practices for radiation safety. This article reviews was aimed to notify radiology managers and technologists in their management with pregnant workers. The paper describes conceptus doses for worker that are associated with radiology practice, reviews the risks and effects of in utero irradiation, and summarizes the current international and professional organizations policies, guidelines and practical aspects regarding the diagnostic radiologic examinations. Conclusion: careful planning, and minimization of radiation dose by engaging proper radiation safety measures as needed, can allow medical staff to perform duties and normal activities without incurring significant risks to the fetus.

Estimating the radiation dose to the fetus during prophylactic internal iliac occlusion in patients with abnormal placentation.

To evaluate the estimated fetal radiation dose during prophylactic internal iliac arterial occlusion in patients with abnormal placenta and to estimate the risk of radiation induced cancer in child age. Prophylactic occlusion of the internal iliac arteries during Caesarean section was performed in 42 patients with placenta praevia and/or placenta accreta spectrum. Fogarty embolectomy catheters were used for prophylactic occlusion of the internal iliac arteries. All procedures were performed in the hybrid operating room using Philips Allura Xper FD 20 X-ray system. Low dose X-ray fluoroscopy (7.5 frames per second) was used. The CODE (Conceptus dose estimation) Software was used to estimate the fetal dose and the risk of radiation induced carcinoma. Fluoroscopy times required for insertion of Fogarty catheters were 0.5-4.2 min (mean: 1.7 min, median: 1.5 min). The estimated radiation dose to the fetus was 0.26-3.36 mGy (mean: 1.49 mGy, median: 1.25 mGy). The risk of radiation induced cancer in child age was 0.01-0.04% (mean 0.02%, median 0.01%). One patient developed thrombosis of a common femoral artery. Prophylactic occlusion of the internal iliac arteries is a simple and safe procedure with minimal risk of complications and with a very low estimated radiation dose to the fetus.

Estimation of the radiation dose in pregnancy: an automated patient-specific model using convolutional neural networks.

The conceptus dose during diagnostic imaging procedures for pregnant patients raises health concerns owing to the high radiosensitivity of the developing embryo/fetus. The aim of this work is to develop a methodology for automated construction of patient-specific computational phantoms based on actual patient CT images to enable accurate estimation of conceptus dose. We developed a 3D deep convolutional network algorithm for automated segmentation of CT images to build realistic computational phantoms. The neural network architecture consists of analysis and synthesis paths with four resolution levels each, trained on manually labeled CT scans of six identified anatomical structures. Thirty-two CT exams were augmented to 128 datasets and randomly split into 80%/20% for training/testing. The absorbed doses for six segmented organs/tissues from abdominal CT scans were estimated using Monte Carlo calculations. The resulting radiation doses were then compared between the computational models generated using automated segmentation and manual segmentation, serving as reference. The Dice similarity coefficient for identified internal organs between manual segmentation and automated segmentation results varies from 0.92 to 0.98 while the mean Hausdorff distance for the uterus is 16.1mm. The mean absorbed dose for the uterus is 2.9mGy whereas the mean organ dose differences between manual and automated segmentation techniques are 0.07%, - 0.45%, - 1.55%, - 0.48%, - 0.12%, and 0.28% for the kidney, liver, lung, skeleton, uterus, and total body, respectively. The proposed methodology allows automated construction of realistic computational models that can be exploited to estimate patient-specific organ radiation doses from radiological imaging procedures. • The conceptus dose during diagnostic radiology and nuclear medicine imaging procedures for pregnant patients raises health concerns owing to the high radiosensitivity of the developing embryo/fetus. • The proposed methodology allows automated construction of realistic computational models that can be exploited to estimate patient-specific organ radiation doses from radiological imaging procedures. • The dosimetric results can be used for the risk-benefit analysis of radiation hazards to conceptus from diagnostic imaging procedures, thus guiding the decision-making process.

Three-Dimensional Printing for Construction of Tissue-Equivalent Anthropomorphic Phantoms and Determination of Conceptus Dose.

The purpose of this study was to develop a road map for rapid construction of anthropomorphic phantoms from computational human phantoms for use in diagnostic imaging dosimetry studies. These phantoms are ideal for performing pregnant-patient dosimetry because the phantoms imitate the size and attenuation properties of an average-sized pregnant woman for multiple gestational periods. The method was derived from methods and materials previously described but adapted for 3D printing technology. A 3D printer was used to transform computational models into a physical duplicate with small losses in spatial accuracy and to generate tissue-equivalent materials characterized for diagnostic energy x-rays. A series of pregnant abdomens were selected as prototypes because of their large size and complex modeling. The process involved the following steps: segmentation of anatomy used for modeling; transformation of the computational model into a printing file format; preparation, characterization, and introduction of phantom materials; and model removal and phantom assembly. The density of the homogenized soft tissue-equivalent substitute was optimized by combining 9.0% by weight of urethane filler powder and 91.0% urethane polymer, which resulted in a mean density of 1.041 g/cm3 measured over 20 samples. Density varied among all of the samples by 0.0026 g/cm3. The total variation in density was 0.00261 g/cm3. The half-value layer of the bone material was measured to be 1.7 mm of bone material at 120 kVp and when simulated by use of the density of the bone tissue-equivalent substitute (1.60 g/cm3) was determined to be 1.61 mm of bone tissue. For dosimetry purposes the phantom provided excellent results for evaluating a site's protocol based on scan range. The 3D printing technology is applicable to the fabrication of phantoms used for performing dosimetry. The tissue-equivalent materials used to substitute for the soft tissue were developed to be highly adaptable for optimization based on the dosimetry application. Use of this method resulted in more automated phantom construction with decreased construction time and increased out-of-slice spatial resolution of the phantoms.

I069] Everything you need to know about dose management of pregnant patients in medical imaging

Purpose The purpose of this presentation is to provide answers to questions related to dose management of pregnant patients needing medical imaging such as ‘how safe are X-ray and nuclear medicine examinations during pregnancy?’, ‘How can we estimate conceptus radiation doses and risks associated with medical imaging?’, How can we avoid accidental irradiation of pregnant patients?’ Methods Methods for the estimation of conceptus dose from diagnostic X-ray, interventional and nuclear medicine examinations have been developed and will be described during this presentation. Advantages and limitations of these methods will be discussed during the presentation. Results Main actions for dose management of pregnant patients will be discussed during the presentation. The CoDE (Conceptus Dose Estimation) online software tool will be presented. CoDE allows a) calculation of conceptus radiation dose and associated risk from X-ray examinations performed on the expectant mother and b) anticipation of conceptus dose for the pregnant employee who participates in fluoroscopically-guided interventional procedures. CoDE is available free of charge (embryodose.med.uoc.gr). Conclusions The involvement of medical physicists is of paramount importance to ensure radiation protection of pregnant patients and their unborn children.

Assessment of CT dose to the fetus and pregnant female patient using patient-specific computational models.

This work provides detailed estimates of the foetal dose from diagnostic CT imaging of pregnant patients to enable the assessment of the diagnostic benefits considering the associated radiation risks. To produce realistic biological and physical representations of pregnant patients and the embedded foetus, we developed a methodology for construction of patient-specific voxel-based computational phantoms based on existing standardised hybrid computational pregnant female phantoms. We estimated the maternal absorbed dose and foetal organ dose for 30 pregnant patients referred to the emergency unit of Geneva University Hospital for abdominal CT scans. The effective dose to the mother varied from 1.1 mSv to 2.0 mSv with an average of 1.6 mSv, while commercial dose-tracking software reported an average effective dose of 1.9 mSv (range 1.7-2.3 mSv). The foetal dose normalised to CTDIvol varies between 0.85 and 1.63 with an average of 1.17. The methodology for construction of personalised computational models can be exploited to estimate the patient-specific radiation dose from CT imaging procedures. Likewise, the dosimetric data can be used for assessment of the radiation risks to pregnant patients and the foetus from various CT scanning protocols, thus guiding the decision-making process. • In CT examinations, the absorbed dose is non-uniformly distributed within foetal organs. • This work reports, for the first time, estimates of foetal organ-level dose. • The foetal brain and skeleton doses present significant correlation with gestational age. • The conceptus dose normalised to CTDI vol varies between 0.85 and 1.63. • The developed methodology is adequate for patient-specific CT radiation dosimetry.

Radiation dose comparison between V/P-SPECT and CT-angiography in the diagnosis of pulmonary embolism

PurposeThe aim of this study is to compare two routine protocols at our institution, CTPA and V/P-SPECT, in terms of radiation dose to the most exposed organs (lungs and breast) and to the embryo/fetus in the case of pregnant patients. MethodsAt our institution, the CTPA protocol includes a contrast enhanced CT (scan parameters: 100kVp, 700mA, 0.5s/rot, pitch 0.984) and in some cases a non-contrast enhanced CT acquisition (120kVp, 400mA, 0.5s/rot, pitch 1.375).In the V/P-SPECT protocol, ventilation SPECT was performed after inhalation of 99mTc-Technegas, reaching 30MBq in the lungs; perfusion was performed after intravenous administration of 60–120MBq of 99mTc-MAA.The absorbed doses (mGy) to lungs and breast from CTPA were estimated using the “ImPACT CT Patient Dosimetry Calculator”. The embryo/fetus dose was estimated for different gestational stages (0–7, 8–12, 13–25 and 26–40weeks) using the web based calculation tool “COnceptus Dose Estimation” (CODE).Doses to organs and embryo/fetus from V/P-SPECT were estimated based on published dose data normalized to administered activity (mGy/MBq). ResultsEmbryo/fetus absorbed doses are similar for CTPA and V/P-SPECT and bellow 1mGy. The calculated dose to the lungs (breast) was 1.3–10.6 (27–136) times higher from CTPA when compared with V/P-SPECT. ConclusionFor the diagnosis of PE in women, if both imaging modalities are available, it is recommended to proceed with V/P-SPECT rather than CTPA due to the considerably lower radiation dose to the breast.

Fetal dose from radiation therapy

The diagnosis of cancer during pregnancy is relatively rare with an incidence up to 0.1%. External-beam radiotherapy may be the treatment of choice for several pregnant patients with malignancies outside the abdominopelvic region. However, radiotherapy at any site above the diaphragm unavoidably exposes the fetus to head leakage radiation and to scattered radiation generated from the therapy machine or within the patient’s body. This fetal radiation exposure may increase the probability for the induction of deterministic and/or stochastic effects. The decision to proceed to radiotherapy can be made only if the fetal dose and the relevant risks are estimated before patient’s irradiation and considered as acceptable. This presentation will describe the procedure of fetal dose determination which is usually performed with thermoluminescent dosimeters placed on physical phantoms simulating the full-scatter geometry of a pregnant patient. Computational methods, based on Monte Carlo simulations on mathematical humanoid phantoms, have also been carried out for estimating the conceptus dose. The possibility of fetal dose reduction with special shielding devices will be discussed. The dependence of the conceptus dose upon the shielding dimensions and the shielding location in respect to the treatment volume or patient’s abdomen will be defined. Practical guidelines will be provided for the protection of the fetus during the treatment planning process. Fetal dose measurements/calculations from radiation therapy for brain, head-neck and breast cancer will be presented. The variation of the fetal dose and risks with the gestational age during treatment and the irradiation parameters will also be determined.

An overview of EFOMP experience, with a focus on EuroSafe imaging

The European Society of Radiology has launched the EuroSafe Imaging Campaign to support and strengthen medical radiation protection across Europe following a holistic, inclusive approach. The European Federation of Organisations for Medical Physics (EFOMP) has supported this campaign since its launch. Medical Physics Experts (MPEs) are involved in medical imaging departments to estimate patient and staff radiation doses, monitor doses using dose tracking methods, establish and review diagnostic reference levels, maintain patient doses within diagnostic reference levels, reduce patient doses while maintaining the image quality needed for diagnosis, develop appropriate examination protocols and train staff in medical radiation protection. These activities are of great importance for CT and interventional radiology, where radiation doses are high. Undoubtedly, MPEs can play a major role in radiation protection in the context of EuroSafe Imaging campaign. Activities where MPEs could be provided valuable expertise include the introduction of decision support tools for the implementation of referral guidelines, the use of dose tracking systems, the development and application of tools for patient exposure records, the development of tools for patient dose reduction, the development of methods for accurate organ dose estimation and risk assessment, the development of methods for accurate conceptus dose estimation, the introduction of innovative education and training platforms and the development and application of tools for accurate and prompt measurement of occupational exposure.

Unborn children: Radiation protection in pregnancy

A diagnostic or interventional X-ray examination of a pregnant patient is sometimes considered to be necessary. In these cases, conceptus dose estimation is needed to assess radiogenic risks to the unborn child. During extra-abdominal examinations, the unborn child is exposed to scattered radiation and in most cases its dose is lower than 1 mGy. A detailed embryo/fetus dose evaluation is not needed for these examinations. Abdominal and/or pelvis X-ray examinations may deliver higher radiation doses to the conceptus. An abdominal CT examination performed on the mother is associated with an embryo/fetus dose of about 10–25 mGy. However, this is only a typical range of dose values. The actual dose depends on factors such as exposure parameters, x-ray tube filtration and use of dose reduction tools such as automatic exposure control. Doses to the unborn child below 100 mGy should not lead to therapeutic abortion. The risk to the embryo/fetus for stochastic effects is assessed on the basis of radiation dose using appropriate conversion coefficients provided by international organizations. Several methods have been developed to estimate doses to unborn children from X-ray examinations. CODE (COnceptus Dose Estimation) is a free web-based software tool (uploaded on embryodose.med.uoc.gr) developed for the estimation of conceptus radiation dose and risks in case of: a) pregnant patients subjected to radiological examinations and b) pregnant employees exposed during fluroscopically guided interventional procedures.

Radiation incidents and accidents in diagnostic and interventional radiology. what to do next in pregnant patients

Despite precautions, pregnant patients occasionally are exposed accidentally to X-rays. Accidental irradiation of pregnant patients occurs during the first postconception weeks. During the first 2 weeks postconception, the embryo will either recover completely or not survive. This is known as ‘all or nothing effect’. From the 3 rd to 8 th week postconception, malformation of body organs is the most possible form of damage. Therefore, after accidental examination of pregnant patients, the gestational age should be known. Accurate estimation of embryo/fetus radiation dose is needed when the mother is after the 2 nd week of gestation and the embryo has been exposed primarily to X-ray beam. CODE (COnceptus Dose Estimation) is a free web-based software tool (uploaded on embryodose.med.uoc.gr) that can be used for estimation of embryo dose from radiography, diagnostic fluoroscopy, CT and fluoroscopically-guided procedures. It is important to avoid accidental irradiation during pregnancy. Careful screening is needed to identify pregnant patients before X-ray examinations. According to ICRP publication 84, ‘investigation of the reproductive status of a female of childbearing age prior to X-ray imaging’ is needed. Also, ‘it is prudent to consider as pregnant any woman of reproductive age presenting herself for an X-ray examination at a time when a menstrual period is overdue, or missed, unless there is information that precludes a pregnancy’. X-ray departments must have posters in the waiting area asking female patients to inform the radiographer or radiologist about a possible pregnancy.

Clinical indications and radiation doses to the conceptus associated with CT imaging in pregnancy: a retrospective study.

To perform an internal audit at a university hospital with the aim of evaluating the number, clinical indication and operating procedure of computed tomography (CT) performed on pregnant patients and of estimating the radiation doses to the conceptus. A retrospective review was conducted of all CT examinations performed in a single centre on pregnant patients between January 2008 and July 2013. The radiation doses to the conceptus were estimated. The results were compared with published data. The number of CT examinations during pregnancy increased from 3-4 per year in 2008-2011 to 11 per year in 2012. The mean estimated conceptus radiation dose was considered negligible for CT of the head and cervical spine, being less than 0.01 mGy, and for CT of the chest, less than 0.1 mGy. The estimated conceptus radiation dose from abdominopelvic CT was on average 28.7 mGy (range 6.7-60.5 mGy). The number of CT scans of pregnant patients increased threefold during the last few years. Most clinical indications and doses were in line with good clinical practice and literature; only in two cases the dose to the conceptus was higher than 50 mGy. • An increase in CT imaging of pregnant patients is of concern. • Clinical indications were in line with good practice. • Estimated conceptus doses were lower or similar to published data. • Internal guidelines for appropriate use of imaging during pregnancy should be established.

MO‐F‐CAMPUS‐I‐02: Occupational Conceptus Doses From Fluoroscopically‐Guided Interventional Procedures

Purpose:The aim of this method was to provide dosimetric data on conceptus dose for the pregnant employee who participates in fluoroscopically‐guided interventional procedures.Methods:Scattered air‐kerma dose rates were obtained for 17 fluoroscopic projections involved in interventional procedures. These projections were simulated on an anthropomorphic phantom placed on the examination table supine. The operating theater was divided into two grids relative to the long table sides. Each grid consisted of 33 cells spaced 0.50 m apart. During the simulated exposures, at each cell, scatter air‐kerma rate was measured at 110 cm from the floor i.e. at the height of the waist of the pregnant worker. Air‐kerma rates were divided by the dose area product (DAP) rate of each exposure to obtain normalized data. For each projection, measurements were performed for 3 kVp and 3 filtration values i.e. for 9 different x‐ray spectra. All measurements were performed by using a modern C‐arm angiographic system (Siemens Axiom Artis, Siemens, Germany) and a radiation meter equipped with an ionization chamber.Results:The results consist of 153 iso‐dose maps, which show the spatial distribution of DAP‐normalized scattered air‐kerma doses at the waist level of a pregnant worker. Conceptus dose estimation is possible using air‐kerma to embryo/fetal dose conversion coefficients published in a previous study (J Cardiovasc Electrophysiol, Vol. 16, pp. 1–8, July 2005). Using these maps, occupationally exposed pregnant personnel may select a working position for a certain projection that keeps abdominal dose as low as reasonably achievable. Taking into consideration the regulatory conceptus dose limit for occupational exposure, determination of the maximum workload allowed for the pregnant personnel is also possible.Conclusion:Data produced in this work allow for the anticipation of conceptus dose and the determination of the maximum workload for a pregnant worker from any fluoroscopically‐guided interventional procedure.This study was supported by the Greek Ministry of Education and Religious Affairs, General Secretariat for Research and Technology, Operational Program ‘Education and Lifelong Learning’, ARISTIA (Research project: CONCERT).

Abdominal CT during pregnancy: a phantom study on the effect of patient centring on conceptus radiation dose and image quality.

To investigate the effect of patient centring on conceptus radiation dose and image quality in abdominal CT during pregnancy. Three anthropomorphic phantoms that represent a pregnant woman at the three trimesters of gestation were subjected to a routine abdominal CT. Examinations were performed with fixed mAs (mAsf) and with the automatic exposure control system (AEC) activated. The percent reduction between mAsf and modulated mAs (mAsmod) was calculated. Conceptus dose (Dc) was measured using thermoluminencent dosimeters. To study the effect of misplacement of pregnant women on Dc, each phantom was positioned at various locations relative to gantry isocentre. Image quality was evaluated on the basis of image noise, signal-to-noise ratio, and contrast-to-noise ratio. The maximum reduction between mAsf and mAsmod was 59.8 %, while the corresponding DC reduction was 59.3 %. DC was found to decrease by up to 25 % and 7.9 % for phantom locations below and above the isocentre, respectively. Image quality deteriorated when AEC was activated, and it was progressively improved from lower to higher than the isocentre locations. Centring errors do not result in an increase in Dc. To maintain image quality, accurate centring is required. • AEC activation reduces conceptus radiation dose at all gestational stages. • Patients should be accurately aligned at the gantry isocenter. • Patient centring deserves increased attention in clinical practice. • Pregnant patient centring errors do not considerably affect conceptus dose.

How to estimate conceptus dose from CT examinations

How to estimate conceptus dose from CT examinations

TH-E-211-11: Conceptus Doses in Abdominal/pelvic CT at An Academic Medical Center

Purpose:To quantify conceptus doses to patients identified as being pregnant and subsequently undergoing abdominal/pelvic CT examinations at an Academic Medical Center. Method:Data in our Radiology Information Service (Image Cast) were reviewed to select all patients in 2010 who had been identified by the referring clinician as being pregnant, and who also underwent a single abdominal/pelvic CT scan.Images on each patient were reviewed on our PACS system to obtain information on the radiation used to perform the scan (CTDIvol and DLP), patient size (AP dimension), as well as the scanned anatomical region and scan length. Conceptus doses were obtained taking into account the amount of radiation used to perform the exam (CTDIvol), the scan length relative to the uterus, and patient size (AP dimension). Results: A total of 37 patients were identified who had a mean age of 28 ± 9 and a mean AP dimension of 27 ± 5 cm. The CTDIvol used to perform these scans increased with increasing patient size (r,2, = 0.26), from an average of 16 mGy in patients with an AP of 21 cm to 29 mGy in patients with an AP of 34 cm. The average scan length was 44 ± 8 cm, and compared to an infinitely long scan resulted in an average uterus/conceptus dose reduction of 4%. The median conceptus dose was 22 mGy, with a 10th percentile value of 11 mGy and a 90th percentile value of 32 mGy. There was negligible correlation (r,2,= 0.02) of conceptus dose with patient AP dimension, showing that the increased CTDIvol used with larger patients was balanced by a corresponding dose reduction in larger patients. Conclusions: The average conceptus dose to identified pregnant patients undergoing abdominal/pelvic CT scans was 22 ± 9 mGy.

A method of estimating conceptus doses resulting from multidetector CT examinations during all stages of gestation

Current methods for the estimation of conceptus dose from multidetector CT (MDCT) examinations performed on the mother provide dose data for typical protocols with a fixed scan length. However, modified low-dose imaging protocols are frequently used during pregnancy. The purpose of the current study was to develop a method for the estimation of conceptus dose from any MDCT examination of the trunk performed during all stages of gestation. The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study to model the Siemens Sensation 16 and Sensation 64 MDCT scanners. Four mathematical phantoms were used, simulating women at 0, 3, 6, and 9 months of gestation. The contribution to the conceptus dose from single simulated scans was obtained at various positions across the phantoms. To investigate the effect of maternal body size and conceptus depth on conceptus dose, phantoms of different sizes were produced by adding layers of adipose tissue around the trunk of the mathematical phantoms. To verify MCNP results, conceptus dose measurements were carried out by means of three physical anthropomorphic phantoms, simulating pregnancy at 0, 3, and 6 months of gestation and thermoluminescence dosimetry (TLD) crystals. The results consist of Monte Carlo-generated normalized conceptus dose coefficients for single scans across the four mathematical phantoms. These coefficients were defined as the conceptus dose contribution from a single scan divided by the CTDI free-in-air measured with identical scanning parameters. Data have been produced to take into account the effect of maternal body size and conceptus position variations on conceptus dose. Conceptus doses measured with TLD crystals showed a difference of up to 19% compared to those estimated by mathematical simulations. Estimation of conceptus doses from MDCT examinations of the trunk performed on pregnant patients during all stages of gestation can be made using the method developed in the current study.

Radiation Dose to the Conceptus from Multidetector CT during Early Gestation: A Method That Allows for Variations in Maternal Body Size and Conceptus Position

To develop a method for estimating the radiation dose to the conceptus from multidetector computed tomography (CT) of the abdomen and pelvis in pregnant patients during the first 7 weeks of gestation. This study was approved by the institutional review board and informed consent was obtained. A CT simulation software package was used to (a) develop voxelized models on the basis of image data from 117 nonpregnant patients who underwent abdominal and pelvic multidetector CT and (b) calculate dose at a position of the uterus assumed to be the position of the conceptus in case of pregnancy during the first 7 weeks of gestation. Regression analysis was carried out to establish the relationship among conceptus dose, patient body size, and distance from the conceptus to the anterior skin surface. Normalized conceptus doses calculated by using the software package ranged from 0.335 to 0.785 mGy per absorbed dose to air. Conceptus dose showed a significant correlation with maternal body size and conceptus depth (R² = 0.793, P < .001). A multivariable correlation of conceptus dose normalized to the free-in-air CT dose index (CTDI(F)) with conceptus depth and patient perimeter was produced for estimating conceptus dose from abdominal and pelvic multidetector CT. Conceptus dose data provided for a specific scanner can be applied to other scanners by using correction factors based on ratios between the weighted CT dose index and CTDI(F), resulting in inaccuracies in the estimation of conceptus dose of less than 12%. The radiation dose to the conceptus from abdominal and pelvic multidetector CT can be estimated with a method that allows for variations in maternal body size and conceptus position.

Conceptus dose from involved-field radiotherapy for Hodgkin's lymphoma on a linear accelerator equipped with MLCs

To estimate the scattered dose to conceptus from involved-field radiotherapy for Hodgkin's lymphoma on a linear accelerator equipped with multileaf collimators. Anthropomorphic phantoms were used to simulate an average pregnant woman at the 1st, 2nd and 3rd trimesters of gestation. Conceptus dose was measured using thermoluminescent dosimeters. Phantom measurements were performed for the minimum, medium and maximum field dimensions that may be employed during radiation therapy to lymph nodes in the neck, axilla, mediastinum and neck-mediastinum. The components of the scattered dose to conceptus were determined. Phantom exposures were generated with a 6-MV photon beam. Neck irradiation with a tumor dose of 35 Gy resulted in a conceptus dose of 1.1-8.7 cGy depending upon the stage of pregnancy, the distance from treatment volume, and the field size applied. The corresponding conceptus dose ranges from radiotherapy in the regions of axilla, mediastinum and neck-mediastinum was 1.2-14.3 cGy, 3.7-57.7 cGy, and 5.1-91.8 cGy, respectively. The contribution of collimator scatter and head leakage to the total conceptus dose varied from 21% to 80% depending upon the irradiation site and gestational age. The conceptus dose associated with cervical node irradiation is below the threshold value of 10 cGy during the entire pregnancy. Radiation therapy to lymph nodes in the axilla, mediastinum and neck-mediastinum may possibly lead to a conceptus dose of > 10 cGy and, therefore, informed decisions about the pregnancy termination should be made.

Therapeutic ERCP and pregnancy: is the radiation risk for the conceptus trivial?

Symptomatic choledocholithiasis can be treated during pregnancy. Conceptus doses ranged from 0.1 mGy to 3 mGy in previous studies. The objectives of the current study were to investigate whether the conceptus dose may exceed the threshold of 10 mGy in the case of a pregnant patient undergoing ERCP, and to provide data for the accurate assessment of a conceptus dose. Monte Carlo methodology and mathematical anthropomorphic phantoms were used to determine normalized conceptus dose data. Phantoms simulated pregnant patients of different body sizes and gestational stages. Monte Carlo simulations were performed to estimate the efficiency of external shielding. University hospital. Twenty-four consecutive patients. All patients underwent therapeutic ERCP. Exposure parameters and dose-area product were recorded during the procedures. The total dose-area product recorded during ERCP procedures ranged between 62 x 10(3) and 491 x 10(3) mGy . cm(2). Monte Carlo normalized conceptus dose data are presented as a function of kV(p), total filtration, gestational stage, and body mass index. The conceptus dose may exceed 10 mGy when the total dose-area product surpasses 130 mGy . cm(2). Variations of conceptus location and size from the average. Conceptus dose from ERCP may occasionally exceed 10 mGy, the dose above which the analytical dose calculation is recommended. The use of external shielding is unnecessary because the associated dose reduction is negligible. The normalized dose data may be used for the accurate estimation of conceptus dose from an ERCP procedure performed on a pregnant patient, regardless of body size, gestational stage, operating parameters, and equipment used.