Interventional Fluoroscopy Procedures Research Articles

Effects of ionizing radiation exposure during pregnancy.

To review the effects of ionizing radiation to the conceptus and the relationship to the timing of the exposure during pregnancy. To consider strategies that would mitigate potential harms associated with exposure to ionizing radiation during pregnancy. Data reported in the peer-reviewed literature on entrance KERMA received from specific radiological examinations were combined with published results from experiment or Monte Carlo modeling of tissue and organ doses per entrance KERMA to estimate total doses that could be received from specific procedures. Data reported in the peer-reviewed literature on dose mitigation strategies, best practices for shielding, consent, counseling and emerging technologies were reviewed. For procedures utilizing ionizing radiation for which the conceptus is not included in the primary radiation beam, typical doses are well below the threshold for causing tissue reactions and the risk of induction of childhood cancer is low. For procedures that include the conceptus in the primary radiation field, longer fluoroscopic interventional procedures or multiphase/multiple exposures potentially could approach or exceed thresholds for tissue reactions and the risk of cancer induction must be weighed against the expected risk/benefit of performing (or not) the imaging examination. Gonadal shielding is no longer considered best practice. Emerging technologies such as whole-body DWI/MRI, dual-energy CT and ultralow dose studies are gaining importance for overall dose reduction strategies. The ALARA principle, considering potential benefits and risks should be followed with respect to the use of ionizing radiation. Nevertheless, as Wieseler et al. (2010) state, "no examination should be withheld when an important clinical diagnosis is under consideration." Best practices require updates on current available technologies and guidelines.

Patient follow-up for possible radiation injury from fluoroscopically-guided interventions: Need to consider high cumulative exposure from multiple procedures

PurposePatient skin dose from interventional fluoroscopy procedures may exceed the threshold of tissue injuries and established guidelines recommend patient follow-up for air kerma at reference point (Ka,r) ≥ 5 Gy for individual procedures. Patients may undergo multiple procedures and skin injuries may be possible by cumulative exposure, even when individually insufficient to cause injury. This study sought to quantify the frequency of patients whose individual procedure doses are below 5 Gy but whose cumulative Ka,r is ≥ 5 Gy. MethodsThis retrospective study analyzed 37,917 consecutive procedures in interventional radiology and vascular surgery at a tertiary-care hospital between January 2016 and June 2021. Radiation dosage was retrieved from the fluoroscopy acquisition systems. For a patient receiving multiple procedures, but each with Ka,r < 5 Gy, cumulative Ka,r within 2, 7, 14, 30, 183, and 365 days was assessed. ResultsNearly 1/3rd (37.4 %) patients underwent multiple procedures. With individual procedures of Ka,r < 5 Gy exclusively, 1.9, 4.4, and 5.6 in 1000 patients received cumulative Ka,r of 5–14.1 Gy from the procedures within 30, 183, and 365 days, respectively. From the procedures within 14 days, 1.3 in 1000 patients received cumulative Ka,r of 5–11.4 Gy; and from those within 7 days, 0.87 in 1000 patients received 5–9.1 Gy. In comparison, 4.3 in 1000 patients received Ka,r of 5–12 Gy from a single procedure. ConclusionsIn the absence of guidelines on patient follow-up for multiple procedures, our study may provide good material for setting up such guidelines.

Diagnostic Reference Levels for Fluoroscopy-guided Gastrointestinal Procedures in Japan from the REX-GI Study: A Nationwide Multicentre Prospective Observational Study

SummaryBackgroundDiagnostic reference levels (DRLs) are required to optimize medical exposure. However, data on DRLs for interventional fluoroscopic procedures are lacking, especially in gastroenterology. This study aimed to prospectively collect currently used radiation doses and help establish national DRLs for fluoroscopy-guided gastrointestinal procedures in Japan.MethodsThis multicentre, prospective, observational study collected actual radiation dose data from endoscopic retrograde cholangiopancreatography (ERCP), interventional endoscopic ultrasound (EUS), balloon-assisted enteroscopy (BAE), enteral metallic stent placement, and enteral tube placement from May 2019 to December 2020. The study outcomes were fluoroscopy time (FT: min), air kerma at the patient entrance reference point (Ka,r: mGy), air kerma area product (PKA: Gycm2), and radiation dose rate (RDR: mGy/min). Additionally, the basic settings of fluoroscopy equipment and the factors related to each procedure were investigated. This study was registered in the UMIN Clinical Trial Registry (UMIN 000036525).FindingsOverall, 12959 fluoroscopy-guided gastrointestinal procedures were included from 23 hospitals in Japan. For 11162 ERCPs, the median/third quartile values of Ka,r (mGy), PKA (Gycm2), and FT (min) were 69/145 mGy, 16/32 Gycm2, and 11/20 min, respectively. Similarly, these values were 106/219 mGy, 23/41 Gycm2 and 17/27 min for 374 interventional EUSs; 53/104 mGy, 16/32 Gycm2 and 10/15 min for 523 metallic stents; 56/104 mGy, 28/47 Gycm2, and 12/18 min for 599 tube placements; and 35/81 mGy, 16/43 Gycm2 and 7/15 min for 301 BAEs, respectively. For the overall radiation dose rate, the median/third quartile values of RDR were 5.9/9.4 (mGy/min). The RDR values at each institution varied widely.InterpretationThis study reports the current radiation doses of fluoroscopy-guided gastrointestinal procedures expressed as DRL quantities. This will serve as a valuable reference for national DRL values.FundingThis work was supported by a clinical research grant from the Japanese Society of Gastroenterology.

Islamic Perspective on Eye Protection from Occupational Radiation Exposures in Interventional Fluoroscopy Procedures: A Review Article

The healthcare staff in interventional fluoroscopy room are exposed to the scattered-radiation from the patient during the procedures. Excessive occupational radiation exposures to their eyes are associated with the formation of radiation-induced cataracts. Therefore, recommendations are set-up to reduce the occupation eye exposure but are often overlooked. Thus, there is a need to incorporate additional value into the recommendations. This review is conducted to incorporate the Islamic perspectives into the recommendations on the eye protection from occupational radiation exposures. Common themes were derived from the recommendations as stated in several guidelines and articles. The relevant Islamic perspective were then identified and linked. The main themes are the responsibilities of the staff in protecting their eyes and the responsibilities of the employers to ensure that their staff are protected. There were several subthemes identified for each main theme. The relevant Islamic perspectives which are related to the identified themes, eyes and concept of radiation protection were discussed in this review. The incorporation of Islamic perspective is an effort to motivate the Muslim staff and employers to see additional values and thus follow the recommendations on the eye lens protection.

Interventional radiologists have a higher rate of chromosomal damage due to occupational radiation exposure: a dicentric chromosome assay.

There are growing concerns regarding radiation exposure in medical workers who perform interventional fluoroscopy procedures. Owing to the nature of certain interventional procedures, workers may be subjected to partial-body radiation exposure that is high enough to cause local damage. We aimed to investigate the level of radiation exposure in interventional radiologists in South Korea by performing cytogenetic biodosimetry, particularly focusing on partial-body exposure. Interventional radiologists (n = 52) completed a questionnaire, providing information about their work history and practices. Blood samples were collected and processed for a dicentric chromosome assay. We determined Papworth's U-value to assess the conformity of dicentrics with the Poisson distribution to estimate the partial-body exposures of the radiologists. Radiologists had a higher number of dicentrics than the normal population and industrial radiographers. Indeed, subjects with a U-value of > 1.96, an indicator of heterogeneous exposure, were observed more frequently; 4.67 ± 0.81% of their body was irradiated at an average dose of 4.64 ± 0.67 Gy. Logistic regression analysis revealed that the total duration of all interventional procedures per week was associated with partial-body exposure levels. Our findings suggest that interventional radiologists had greater chromosomal damages than those in other occupational groups, and their partial-body exposure levels might be high enough to cause local damage. Use of special dosimeters to monitor partial-body exposure, as well as restricting the time and frequency of interventional procedures, could help reduce occupational radiation exposure. • Interventional radiologists had a higher number of dicentrics than the normal population and industrial radiographers. • The level of partial-body exposure of interventional radiologists might be high enough to cause occupational local damage such as a skin cancer in fingers. • Restricting the duration and frequency of interventional procedures might be helpful in reducing occupational radiation exposure.

Toward a priori noise characterization for real-time edge-aware denoising in fluoroscopic devices

BackgroundLow-dose X-ray images have become increasingly popular in the last decades, due to the need to guarantee the lowest reasonable patient’s exposure. Dose reduction causes a substantial increase of quantum noise, which needs to be suitably suppressed. In particular, real-time denoising is required to support common interventional fluoroscopy procedures. The knowledge of noise statistics provides precious information that helps to improve denoising performances, thus making noise estimation a crucial task for effective denoising strategies. Noise statistics depend on different factors, but are mainly influenced by the X-ray tube settings, which may vary even within the same procedure. This complicates real-time denoising, because noise estimation should be repeated after any changes in tube settings, which would be hardly feasible in practice. This work investigates the feasibility of an a priori characterization of noise for a single fluoroscopic device, which would obviate the need for inferring noise statics prior to each new images acquisition. The noise estimation algorithm used in this study was tested in silico to assess its accuracy and reliability. Then, real sequences were acquired by imaging two different X-ray phantoms via a commercial fluoroscopic device at various X-ray tube settings. Finally, noise estimation was performed to assess the matching of noise statistics inferred from two different sequences, acquired independently in the same operating conditions.ResultsThe noise estimation algorithm proved capable of retrieving noise statistics, regardless of the particular imaged scene, also achieving good results even by using only 10 frames (mean percentage error lower than 2%). The tests performed on the real fluoroscopic sequences confirmed that the estimated noise statistics are independent of the particular informational content of the scene from which they have been inferred, as they turned out to be consistent in sequences of the two different phantoms acquired independently with the same X-ray tube settings.ConclusionsThe encouraging results suggest that an a priori characterization of noise for a single fluoroscopic device is feasible and could improve the actual implementation of real-time denoising strategies that take advantage of noise statistics to improve the trade-off between noise reduction and details preservation.

A diagnostic medical physicist’s guide to the American College of Radiology Fluoroscopy Dose Index Registry

A diagnostic medical physicist’s guide to the American College of Radiology Fluoroscopy Dose Index Registry

Using a convolutional neural network for human recognition in a staff dose management software for fluoroscopic interventional procedures.

Staff dose management is a continuing concern in fluoroscopically-guided interventional (FGI) procedures. Being unaware of radiation scatter levels can lead to unnecessarily high stochastic and deterministic risks due to the effects of absorbed dose by staff members. Our group has developed a scattered-radiation display system (SDS) capable of monitoring system parameters in real-time using a controller-area network (CAN) bus interface and displaying a color-coded mapping of the Compton-scatter distribution. This system additionally uses a time-of-flight depth sensing camera to track staff member positional information for dose rate updates. The current work capitalizes on our body tracking methodology to facilitate individualized dose recording via human recognition using 16-bit grayscale depth maps acquired using a Microsoft Kinect V2. Background features are removed from the images using a depth threshold technique and connected component analysis, which results in a body silhouette binary mask. The masks are then fed into a convolutional neural network (CNN) for identification of unique body shape features. The CNN was trained using 144 binary masks for each of four individuals (total of 576 images). Initial results indicate high-fidelity prediction (97.3% testing accuracy) from the CNN irrespective of obstructing objects (face masks and lead aprons). Body tracking is still maintained when protective attire is introduced, albeit with a slight increase in positional data error. Dose reports are then able to be produced which contain cumulative dose to each staff member at the eye lens level, waist level, and collar level. Individualized cumulative dose reporting through the use of a CNN in addition to real-time feedback in the clinic will lead to improved radiation dose management.

Rogue cell-like chromosomal aberrations in peripheral blood lymphocytes of interventional radiologists: A case study

We report two cases of interventional radiologists who had been exposed to radiation while performing fluoroscopically-guided interventional procedures (FGIPs), mainly transcatheter arterial chemoembolization, percutaneous catheter drainage, and percutaneous transhepatic biliary drainage procedures, for over 10 years. They had a unique multi-aberrant cell type with not only high numbers of dicentrics and/or centric rings but also excess acentric double minutes, similar to a rogue cell. As revealed in a self-administered questionnaire, they wore personal dosimeters and protective equipment at all times and used shielding devices during interventional fluoroscopy procedures. However, the exposed dose levels derived from cytogenetic dosimetry were much higher than the doses recorded on their personal dosimeters. A large number of unstable and stable chromosomal aberrations that were found in the peripheral blood lymphocytes of these interventional radiologists might be due to repeated and long-term exposure to ionizing radiation while performing FGIPs. Further investigations of chromosomal aberrations in interventional radiologists may improve the understanding of the long-term effects of radiation exposure on medical personnel.

Review of airkerma-area product, effective dose and dose conversion coefficients for non-cardiac interventional fluoroscopy procedures.

To provide current data on average air kerma-area product (PKA ) and effective dose (E) for noncardiac interventional fluoroscopy procedures and suggested values of dose coefficients (DCE ) for conversion of PKA to estimates of effective dose. A PubMed literature search covering the time period from 2006 to August 2019 was performed to obtain recent data on PKA , E and DCE for interventional fluoroscopy procedures. There is very wide variation in the reported values of PKA , E, and DCE in the literature. A number of factors are involved in this variability and the resultant uncertainty in average values of these dose quantities. The values of PKA , average E and suggested DCE presented here can be of use for comparison of the radiation detriment from different procedures and may be useful for categorizing detriment within an order of magnitude or so. They do not represent actual or expected radiation dose or detriment from any specific procedure or for a specific patient and should be not be used as such.

A study to assess the knowledge and practice of medical professionals on radiation protection in interventional radiology.

Objective:Ionizing radiation has been extensively used in medical procedures throughout the world. Such interventional radiological procedures could result in occupational exposure that needs urgent control. Therefore, MPs (medical professionals) should receive education and appropriate training on occupational radiation protection. In this context, the present study is aimed to investigate the MPs' knowledge and practice regarding radiation protection principles during interventional radiological procedures.Material and Methods:A descriptive questionnaire-based study was carried out among 215 MPs involved in interventional fluoroscopy procedures. The practice of 31 MPs was studied using a checklist based on ALARA principles and ICRP guidelines.Results:A total of 43.3% and 45.1% answered correctly for knowledge and practice. However, the difference between radiation protection knowledge and practice between the physicians and nurses was statistically significant. The knowledge and practice survey of MPs demonstrated that nurses rarely adhered to radiation-protection measures.Conclusion:The present study reflects the lack of knowledge and practice concerning radiation protection concepts among the nurses. This deficiency needs to be resolved by periodic practical radiation protection courses in the curriculum of medicine.

Radiation protection value to the operator from augmented reality smart glasses in interventional fluoroscopy procedures using phantoms

IntroductionSmart glasses can be adapted to display radiographic images to allow clinician's gaze not to be directionally fixed or predetermined by computer monitor location. This study presents an analysis of eye lens dose during interventional fluoroscopy guided procedures, comparing fixed monitor positions against the use of smart glasses. MethodsUsing a head phantom (simulating the clinician), thermoluminescent dosimeters and lead shielded glasses, the dose to the eye was measured for different head ‘rotations and tilts’ for: gaze directed towards the main scattering source (patient/primary beam) to represent potential gaze direction if smart glasses are used; gaze directed to a range of potential computer monitor positions. An anthropomorphic pelvis phantom was utilised to simulate the patient. Accumulated dose rates (μGy sˉ1) from five 10-second exposures at 75 kV 25.2 mAs were recorded. ResultsAn average DAP reading of 758.84 cGy cm2 was measured during each 10 second exposure. Whilst wearing lead shielded glasses a 6.10 – fold reduction in dose rate to the lens is possible (p < 0.05). Influence of the direction of gaze by the clinician demonstrated a wide range of dose rate reduction from 3.13% (p = 0.16) to 143.69% (p < 0.05) when the clinician's gaze was towards the main scattering source. Increased dose rate to the clinician's eyes was received despite wearing lead shielded glasses, as the angle of gaze moved 45° and 90° from 0°. ConclusionIf the clinician's gaze is directed towards the main scattering source a potential exists for reducing eye lens dose compared with fixed location computer monitors. Introduction of lead lined smart glasses into interventional radiology may lead to improvements in patient care, reducing the need for the clinician to look away from the patient to observe a radiographic image.

Estimating Fluoroscopic Peak Skin Dose Using Manual Calculations.

Not all healthcare providers can afford to purchase commercially available programs that can quickly and easily provide peak skin dose estimations for patients undergoing diagnostic and international fluoroscopic procedures. The air kerma reference point exposure, Ka,r, available on all equipment manufactured after 2006, may over or under estimate the patient's peak skin dose. The total air kerma reference point exposure provided at the end of a case might be on the order of 20 Gy for a patient, indicating that a Joint Commission 'sentinel event' may have occurred. An investigation to determine whether a sentinel event has occurred becomes necessary. This article will introduce information available to the investigating health physicist for data mining, how to process that information, and then how best to interpret the results. I have used this system of data mining and analysis to effectively influence how physicians performing diagnostic and interventional fluoroscopic procedures use fluoroscopic equipment. Arriving at an answer is not simple; it is time consuming, and the methodologies are imperfect. Your effort can result in improved utilization of fluoroscopic equipment at your institution which in turn will lower patient and staff doses.

Occupational radiation exposure and its health effects on interventional medical workers: study protocol for a prospective cohort study

IntroductionAlthough fluoroscopically guided procedures involve a considerably high dose of radiation, few studies have investigated the effects of radiation on medical workers involved in interventional fluoroscopy procedures. Previous research remains...

Assessment of organ and effective dose when using region-of-interest attenuators in cone-beam CT and interventional fluoroscopy.

In some medical-imaging procedures using cone-beam CT (CBCT) and fluoroscopy, only the center of the field of view (FOV) may be needed to be visualized with optimal image quality. To reduce the dose to the patient while maintaining visualization of the entire FOV, a Cu attenuator with a circular aperture for the region of interest (ROI) is used. The potential organ and effective dose reductions of ROI imaging when applied to CBCT and interventional fluoroscopic procedures were determined using EGSnrc Monte Carlo code. The Monte Carlo model was first validated by comparing the surface dose distribution in a solid-water block phantom with measurement by Gafchromic film. The dependence of dose reduction on the ROI attenuator thickness, the opening size of the ROI, the axial beam position, and the location of the different organs for both neuro and thoracic imaging was evaluated. The results showed a reduction in most organ doses of 45% to 70% and in effective dose of 46% to 66% compared to the dose in a CBCT scan and in an interventional procedure without the ROI attenuator. This work provides evidence of a substantial reduction of organ and effective doses when using an ROI attenuator during CBCT and fluoroscopic procedures.

Patient Radiation Shielding Methods in Interventional Radiology: A Literature Review

Background: The increasing complexity and numbers of interventional fluoroscopy procedures have led to increasing patient radiation doses. Consequently, radiation protection of the patients undergoing X-ray procedures is essential. During any medical procedure that uses radiation, the as low as reasonably achievable principle should always be followed. Objectives: To investigate available shielding methods in an effort to further awareness and understanding of existing preventive measures related to patient exposure in interventional radiology. Methods: Searches were conducted to locate literature discussing the effectiveness of commercially available shields. Literature containing information regarding eye and thyroid shielding was identified. The selected studies were examined using the following topics as guidelines: the effectiveness of the shield (percentage of dose reduction), the shields effect on image quality, arguments for or against its use (including practicality) and overall recommendation for its use in clinical practice. Results: Only a limited number of studies have been performed on the use of shields for the eyes and thyroid, but the evidence shows an overall benefit to their use. This study demonstrates how thyroid shields can be used to reduce dose to the thyroid by almost half. The use of thyroid and eyes shields is not routine but has been studied in patients during interventional procedures. The effect of shielding on image quality was not remarkable in a majority of studies. Although it is noted that more studies need to be conducted regarding the impact on image quality, the currently published literature stresses the importance of shielding in reducing dose. Conclusions: Available shields for the thyroid and eyes should be implemented in clinical practice. Further research is needed to demonstrate the prevalence of shielding in the clinical setting.

Organ and effective dose reduction for region-of-interest (ROI) CBCT and fluoroscopy.

In some medical-imaging procedures using CBCT and fluoroscopy, it may be needed to visualize only the center of the field-of-view with optimal quality. To reduce the dose to the patient as well as enable increased contrast in the region of interest (ROI) during CBCT and fluoroscopy procedures, a 0.7 mm thick Cu ROI attenuator with a circular aperture 12% of the FOV was used. The aim of this study was to quantify the dose-reduction benefit of ROI imaging during a typical CBCT and interventional fluoroscopy procedures in the head and torso. The Toshiba Infinix C-Arm System was modeled in BEAMnrc/EGSnrc with and without the ROI attenuator. Patient organ and effective doses were calculated in DOSXYZnrc/EGSnrc Monte-Carlo software for CBCT and interventional procedures. We first compared the entrance dose with and without the ROI attenuator on a 20 cm thick solid-water block. Then we simulated a CBCT scan and an interventional fluoroscopy procedure on the head and torso with and without an ROI attenuator. The results showed that the entrance-surface dose reduction in the solid water is about 85.7% outside the ROI opening and 10.5% in the ROI opening. The results showed a reduction in most organ doses of 45%-70% and in effective dose of 46%-66% compared to the dose in a CBCT scan and in an interventional procedure without the ROI attenuator. This work provides evidence of substantial reduction of organ and effective doses when using an ROI attenuator during CBCT and fluoroscopic procedures.

TU‐D‐209‐02: A Backscatter Point Spread Function for Entrance Skin Dose Determination

Purpose:To determine the distribution of backscattered radiation to the skin resulting from a non‐uniform distribution of primary radiation through convolution with a backscatter point spread function (PSF).Methods:A backscatter PSF is determined using Monte Carlo simulation of a 1 mm primary beam incident on a 30 × 30 cm × 20 cm thick PMMA phantom using EGSnrc software. A primary profile is similarly obtained without the phantom and the difference from the total provides the backscatter profile. This scatter PSF characterizes the backscatter spread for a “point” primary interaction and can be convolved with the entrance primary dose distribution to obtain the total entrance skin dose. The backscatter PSF was integrated into the skin dose tracking system (DTS), a graphical utility for displaying the color‐coded skin dose distribution on a 3D graphic of the patient during interventional fluoroscopic procedures. The backscatter convolution method was validated for the non‐uniform beam resulting from the use of an ROI attenuator. The ROI attenuator is a copper sheet with about 20% primary transmission (0.7 mm thick) containing a circular aperture; this attenuator is placed in the beam to reduce dose in the periphery while maintaining full dose in the region of interest. The DTS calculated primary plus backscatter distribution is compared to that measured with GafChromic film and that calculated using EGSnrc Monte‐Carlo software.Results:The PSF convolution method used in the DTS software was able to account for the spread of backscatter from the ROI region to the region under the attenuator. The skin dose distribution determined using DTS with the ROI attenuator was in good agreement with the distributions measured with Gafchromic film and determined by Monte Carlo simulationConclusion:The PSF convolution technique provides an accurate alternative for entrance skin dose determination with non‐uniform primary x‐ray beams.Partial support from NIH Grant R01‐EB002873 and Toshiba Medical Systems Corp.

TU‐D‐209‐05: Automatic Calculation of Organ and Effective Dose for CBCT and Interventional Fluoroscopic Procedures

Purpose:To compare PCXMC and EGSnrc calculated organ and effective radiation doses from cone‐beam computed tomography (CBCT) and interventional fluoroscopically‐guided procedures using automatic exposure‐event grouping.Methods:For CBCT, we used PCXMC20Rotation.exe to automatically calculate the doses and compared the results to those calculated using EGSnrc with the Zubal patient phantom. For interventional procedures, we use the dose tracking system (DTS) which we previously developed to produce a log file of all geometry and exposure parameters for every x‐ray pulse during a procedure, and the data in the log file is input into PCXMC and EGSnrc for dose calculation. A MATLAB program reads data from the log files and groups similar exposures to reduce calculation time. The definition files are then automatically generated in the format used by PCXMC and EGSnrc. Processing is done at the end of the procedure after all exposures are completed.Results:For the Toshiba Infinix CBCT LCI‐Middle‐Abdominal protocol, most organ doses calculated with PCXMC20Rotation closely matched those calculated with EGSnrc. The effective doses were 33.77 mSv with PCXMC20Rotation and 32.46 mSv with EGSnrc. For a simulated interventional cardiac procedure, similar close agreement in organ dose was obtained between the two codes; the effective doses were 12.02 mSv with PCXMC and 11.35 mSv with EGSnrc. The calculations can be completed on a PC without manual intervention in less than 15 minutes with PCXMC and in about 10 hours with EGSnrc, depending on the level of data grouping and accuracy desired.Conclusion:Effective dose and most organ doses in CBCT and interventional radiology calculated by PCXMC closely match those calculated by EGSnrc. Data grouping, which can be done automatically, makes the calculation time with PCXMC on a standard PC acceptable. This capability expands the dose information that can be provided by the DTS.Partial support from NIH Grant R01‐EB002873 and Toshiba Medical Systems Corp.

TU‐D‐209‐03: Alignment of the Patient Graphic Model Using Fluoroscopic Images for Skin Dose Mapping

Purpose:The Dose Tracking System (DTS) was developed to provide realtime feedback of skin dose and dose rate during interventional fluoroscopic procedures. A color map on a 3D graphic of the patient represents the cumulative dose distribution on the skin. Automated image correlation algorithms are described which use the fluoroscopic procedure images to align and scale the patient graphic for more accurate dose mapping.Methods:Currently, the DTS employs manual patient graphic selection and alignment. To improve the accuracy of dose mapping and automate the software, various methods are explored to extract information about the beam location and patient morphology from the procedure images. To match patient anatomy with a reference projection image, preprocessing is first used, including edge enhancement, edge detection, and contour detection. Template matching algorithms from OpenCV are then employed to find the location of the beam. Once a match is found, the reference graphic is scaled and rotated to fit the patient, using image registration correlation functions in Matlab. The algorithm runs correlation functions for all points and maps all correlation confidences to a surface map. The highest point of correlation is used for alignment and scaling. The transformation data is saved for later model scaling.Results:Anatomic recognition is used to find matching features between model and image and image registration correlation provides for alignment and scaling at any rotation angle with less than onesecond runtime, and at noise levels in excess of 150% of those found in normal procedures.Conclusion:The algorithm provides the necessary scaling and alignment tools to improve the accuracy of dose distribution mapping on the patient graphic with the DTS.Partial support from NIH Grant R01‐EB002873 and Toshiba Medical Systems Corp.