PAE planning: Radiation exposure and image quality of CT and CBCT.

PURPOSE: To determine accurate organ doses, effective doses, and image quality of computed tomography (CT) compared with cone beam CT (CBCT) for correct identification of prostatic arteries. METHOD: A dual-energy CT scanner and a flat-panel angiography system were used. Dose measurements (gallbladder (g), intestine (i), bladder (b), prostate (p), testes (t), active bone marrow of pelvis (bmp) and femura (bmf)) were performed using an anthropomorphic phantom with 65 thermoluminescent dosimeters in the pelvis and abdomen region. For the calculation of the contrast-to-noise ratio (CNR) of the pelvic arteries, a patient whose weight and height were almost identical to those of the phantom was selected for each examination type. RESULTS: The effective dose of CT was 2.7 mSv and that of CBCT was 21.8 mSv. Phantom organ doses were lower for CT than for CBCT in all organs except the testes (g: 1.2 mGy vs. 3.3 mGy, i: 5.8 mGy vs. 23.9 mGy, b: 6.9 mGy vs. 19.4 mGy, p: 6.4 mGy vs. 13.2 mGy, t: 4.7 mGy vs. 2.4 mGy, bmp: 5.1 mGy vs. 18.2 mGy, bmf: 3.3 mGy vs. 6.6 mGy). For human pelvic arteries, the CNR of CT was better than that of CBCT, with the exception of one prostate artery that showed stenosis on CT. Evaluation by experienced radiologists also confirmed the better detectability of prostate arteries on CT examination. CONCLUSIONS: In our study preprocedural CT had lower organ doses and better image quality comparedd with CBCT and should be considered for the correct identification of prostatic arteries.

In vitro measurements of radiation exposure with different modalities (computed tomography, cone beam computed tomography) for imaging the petrous bone with a pediatric anthropomorphic phantom.

BACKGROUND: Various imaging modalities, such as multi-detector computed tomography (CT) and cone beam CT are commonly used in infants for the diagnosis of hearing loss and surgical planning of implantation hearing aid devices, with differing results. OBJECTIVE: We compared three different imaging modalities available in our institution, including a high-class CT scanner, a mid-class CT scanner and an angiography system with a cone beam CT option, for image quality and radiation exposure in a phantom study. MATERIALS AND METHODS: While scanning an anthropomorphic phantom imitating a 1-year-old child with vendor-provided routine protocols, organ doses, surface doses and effective doses were determined for these three modalities with thermoluminescent dosimeters. The image quality was evaluated using the signal difference to noise ratio (SDNR) and the spatial resolution of a line-pair insert in the phantom head. The dose efficiency, defined as the ratio of SDNR and effective dose, was also compared. RESULTS: The organ and surface doses were lowest with the high-class CT protocol, but the image quality was the worst. Image quality was best with the cone beam CT protocol, which, however, had the highest radiation exposure in this study, whereas the mid-class CT was in between. CONCLUSION: Based on our results, high-end CT should be used for surgical planning because it has the lowest dose, while the image quality is still sufficient for this purpose. However, if highest image quality is needed and required, e.g., by ENT surgeons, the other modalities should be considered.

CAN THE SIZE-SPECIFIC DOSE ESTIMATE BE DERIVED FROM THE BODY MASS INDEX? A FEASIBILITY STUDY.

Size-specific dose estimate ($\mathbf{SSDE}$) index appears to be more suitable than the commonly used volume computed tomography dose index ($\mathbf{C}{\mathbf{TDI}}_{\mathbf{vol}}$) to estimate the dose delivered to the patient during a computed tomography (CT) scan. We evaluated whether an ${\mathbf{SSDE}}_{\mathbf{BMI}}$ can be determined from the patient's body mass index ($\mathbf{BMI}$) with sufficient reliability in the case that a $\mathbf{SSDE}$ is not given by the CT scanner. For each of the three most used examination types, CT examinations of 50 female and 50 male patients were analyzed. The $\mathbf{SSDE}$ values automatically provided by the scanner were compared with ${\mathbf{SSDE}}_{\mathbf{BMI}}$ determined from $\mathbf{C}{\mathbf{TDI}}_{\mathbf{vol}}$ and $\mathbf{BMI}$. A good accordance of ${\mathbf{SSDE}}_{\mathbf{BMI}}$ and $\mathbf{SSDE}$ was found for the chest and abdominal regions. A low correlation was observed for the head region. The presented method is a simple and practically useful surrogate approach for the chest and abdominal regions but not for the head.

Feasibility of the Big 5-Jena eCS Protocol : First Experience Implementing a New Extended CT Protocol in the Initial Diagnostics of Ischemic Stroke.

PURPOSE: The most common protocols in the initial diagnostic of acute ischemic stroke do not assess cardiogenic or aortic causes of embolism. These are usually evaluated later by transthoracic (TTE) or transesophageal (TEE) echocardiography. This study aimed to evaluate the feasibility of a diagnostic tool for thoracic cardiovascular thrombi according to the first experience with a new extended cardio-stroke protocol (Big 5-Jena eCS protocol) in acute stroke patients. METHODS: Retrospective analyses of the tomography scans database of the Jena University Hospital were performed. We included a total of 67 patients in the feasibility analyses, based on the evaluation of three outcomes. RESULTS: Primary outcome: the Big 5-Jena eCS protocol was able to detect thoracic cardiovascular thrombi in a total of 20 patients in different locations including the arch of the aorta, the aortic valve, the left atrium, the left atrial appendage, the left ventricle, and the pulmonary arteries. Secondary outcome: implementating the protocol did not result in a significant elevation of the radiation exposure compared to traditional protocols. Tertiary outcome: the new protocol identified seven cases that were considered negative by echocardiography. CONCLUSION: The implementation of an extended cardio-stroke protocol is feasible, no significantly time-consuming, acquiring assessable imaging, and maintaining radiation exposure acceptable. The Big 5-Jena eCS protocol was also able to detect some thrombi not reported by TTE or TEE; however, due to our data's explorative character, a conclusive comparison with cardiac ultrasound is not possible. A prospective pilot study and clinical trials should be conducted to assess the diagnostic accuracy of this protocol compared to echocardiography and determine the potential impact on diagnostic and treatment decisions.

Prenatal radiation exposure in diagnostic and interventional radiology. / Pränatale Strahlenexposition in der diagnostischen und interventionellen Radiologie.

BACKGROUND: The exposure of a pregnant woman to X-rays is an event that can cause uncertainty for all concerned. This review provides guidance on how to assess such a situation and how to determine the dose to the unborn child. In general, the use of X-rays in pregnant women in radiology should be avoided. If possible, alternatives should be used, or examinations postponed to a time after the pregnancy. This review gives a summary of the procedure for determining the radiation exposure of a pregnant woman. METHOD: Based on the previous report of 2002 and the literature on prenatal radiation exposure published thereafter, the DGMP/DRG report on the procedure for the assessment of prenatal radiation exposure was adapted to the current state of science and technology. RESULTS: Typically, only relatively low radiation exposures of less than 20 mSv occur for the unborn child in X-ray diagnostics in the vast majority of cases. At these dose level the additional risk of damage to the embryo or fetus caused by the radiation is low and therefore only a rough conservative estimate using tabulated values are made. Only in a few types of examination (CT and interventional radiology) higher doses values might occur in the uterus. Instead of dose estimates (step 1 in the two-step model) in these cases the calculation of dose (step 2) are required and further action by the physician may be necessary. CONCLUSIONS: During the assessment, it is useful to initially use simple conservative estimation procedures to quickly determine whether a case falls into this large group less than 20 mSv, where there is a very low risk to the unborn child. If this is the case, the pregnant woman should be informed immediately by the doctor who performed the examination/treatment. This avoids a psychological burden on the patient. The DGMP/DRG report suggests a relatively simple, clearly structured procedure with advantages for all parties involved (physician, medical physics experts, MTRA and patient). KEY POINTS: · The DGMP/DRG report on prenatal radiation exposure describes the procedure for calculating radiation exposures and the associated risks for the unborn child.. · Using the two-step model, only a simple assessment based on the first step is necessary for most prenatal radiation exposures.. · With the given tables it is possible to estimate individual risks for the unborn child taking into account the radiation exposure.. · Only in the rare case that the first estimate results in a uterine dose larger 20 mSv a more accurate calculation is necessary.. CITATION FORMAT: · Fiebich M, Block A, Borowski M et al. Prenatal radiation exposure in diagnostic and interventional radiology. Fortschr Röntgenstr 2021; 193: 778 - 786.

Influence of Interventionists' Experience on Radiation Exposure of Patients Who Underwent Prostate Artery Embolization: 4-Year Results from a Retrospective, Single-Center Study.

PURPOSE: To assess radiation exposure in men undergoing prostate artery embolization (PAE) for the treatment for symptomatic, benign prostatic hyperplasia depending on growing experience of interventional radiologists over a 4-year period. METHODS: A total of 250 consecutive patients underwent PAE at a single center. Data on radiation exposure [dose area product (DAP), effective dose (ED), entrance skin dose (ESD), and fluoroscopy time (FT)] were retrospectively evaluated. Primary outcomes of interest were patient radiation exposure in five consecutive groups of 50 patients each and Pearson correlation with the number of patients treated. RESULTS: Median DAP, ED, and ESD during prostate artery embolization were significantly higher in the first compared to the second 50 patients (56 298 µGym2 vs. 24 709 µGym2, p < 0.001, 146.4 mSv vs. 64.2 mSv, p < 0.001, and 5.1 Gy vs. 2.4 Gy, p < 0.001, respectively). The following consecutive groups did not differ significantly from the respective preceding group in terms of DAP, ED, and ESD. Number of digital subtraction angiography series, FT, and procedure time decreased with increasing operator experience (Pearson's r = - 0.240, p < 0.001, r = - 0.269, p < 0.001, and r = - 0.504, p < 0.001, respectively). Bilateral prostate artery embolization was associated with less ESD and shorter FT than unilateral embolization (median 2.5 vs. 3.5 Gy, p = 0.02, and 26 min vs. 42 min, p < 0.001, respectively). CONCLUSION: Exposure to radiation in men who underwent PAE decreased with growing operator experience and decreasing complexity of procedures.

Main force directions of trunk muscles: A pilot study in healthy male subjects.

Muscles work most effectively along their anatomically defined action vector(s) which has implications in training and therapeutics. Action vectors can easily be identified in extremity muscles and smaller muscles of the trunk, but are less clear in larger trunk muscles. Trunk muscle exercises and diagnostics have traditionally relied on tasks in the sagittal plane - a practice that is being reconsidered. Therefore, this study aimed at identifying main force directions (MFDs) of major trunk muscles expressed in terms of deviation from the sagittal plane. 20 healthy male subjects underwent graded isometric submaximal static load applications on their trunk by application of simultaneous and incremental tilting and rotating from vertical to horizontal at rotational angles of 45° starting from 0° (forward tilting) around 360° with only the lower body secured. Surface EMG (SEMG) from six trunk muscles on each body side was recorded. The MFD of each trunk muscle was estimated by considering SEMG amplitudes of all rotational angles, separately for all tilt angles, and was expressed as angular deviation from sagittal plane. The calculated MFDs of trunk muscles deviated from sagittal plane to differing extents. Mean MFD angle was smallest (more parallel to sagittal plane) for rectus abdominis muscle (±14°), becoming more lateral for external oblique (OE, ±32°) and internal oblique abdominal muscles (OI, ±47°). As tilt angle increased, MFD angles increased for OE, but decreased for OI. Iliocostalis muscle showed an almost laterally directed MFD with systematic dependency on body side (-90° for left and +75° for right side). Both paravertebral muscles (longissimus and multifidus muscles) showed almost identical MFD angles of about ±145° and varied the least with tilt angle. All trunk muscles' MFDs deviate from sagittal plane and, in addition to flexing and extending, have both bending and/or rotational capabilities. MFDs of oblique abdominal muscles are systematically altered by tilt angle in accordance with their more divergent fiber directionality. The results provide a basis for specifically targeted diagnostics and training of trunk muscles.

Patient-related quality assurance with different combinations of treatment planning systems, techniques, and machines : A multi-institutional survey.

PURPOSE: This project compares the different patient-related quality assurance systems for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques currently used in the central Germany area with an independent measuring system. MATERIALS AND METHODS: The participating institutions generated 21 treatment plans with different combinations of treatment planning systems (TPS) and linear accelerators (LINAC) for the QUASIMODO (Quality ASsurance of Intensity MODulated radiation Oncology) patient model. The plans were exposed to the ArcCHECK measuring system (Sun Nuclear Corporation, Melbourne, FL, USA). The dose distributions were analyzed using the corresponding software and a point dose measured at the isocenter with an ionization chamber. RESULTS: According to the generally used criteria of a 10 % threshold, 3 % difference, and 3 mm distance, the majority of plans investigated showed a gamma index exceeding 95 %. Only one plan did not fulfill the criteria and three of the plans did not comply with the commonly accepted tolerance level of ±3 % in point dose measurement. CONCLUSION: Using only one of the two examined methods for patient-related quality assurance is not sufficiently significant in all cases.