Red Bone Marrow Distribution Research Articles

Вычислительный фантом для дозиметрии красного костного мозга пятилетнего ребенка от инкорпорированных бета-излучателей

The red bone marrow (RBM) exposure due to bone-seeking radionuclides can lead to grave medical consequences. In particular, the increased risk of leukemia in people exposed due to contamination of the Techa River in 1950s is associated with the RBM exposure due to 89,90Sr. Improvement of the internal RBM dosimetry methods includes the development of computational phantoms that represent 3D models of the skeletal sites. Modeling radiation transport within such phantoms enables estimation of conversion factors from the radionuclide activity in the bone to the RBM dose rate. This paper is an extension study focused on generating a set of computational phantoms representing skeletons of individuals of different ages. The aim was to develop a computational phantom representing a 5-yearold child for internal RBM dosimetry from incorporated beta emitters. The phantoms of the skeletal sites with active hematopoiesis were created using the original Stochastic Parametric Skeletal Dosimetry (SPSD) method. With this method, every such site represented a set of smaller phantoms of simple geometric shape. RBM distribution across the skeleton, bone size, characteristics of bone micro-architecture, as well as density and chemical composition of the simulated media (RBM, bone) were determined based on the published data. As a result, a computational phantom of the major skeletal sites with active hematopoiesis representing a 5-year-old child was generated that included 43 phantoms of bone fragments. Linear dimensions of phantoms were within 3–75 mm. Micro-architecture parameters varied greatly: BV/TV ratio —13–52%, Tb. Th. — 0.09–0.29 mm, Tb. Sp. —0.48–0.98 mm.

OA157] Evaluation of bone and bone marrow doses in multi-slice CT thorax examinations of children and young adolescents

Purpose To accurately estimate absorbed doses to primarily irradiated bone and red bone marrow (RBM) structures in pediatric computed tomography (CT) examinations considering a) patient size, b) tube current modulation (TCM), and c) age-specific distributions of active red marrow in bones. Methods Routine thorax CT examinations of 30 pediatric patients, ranging from neonate to 16-year-old, were simulated using a voxelized, patient-specific Monte Carlo (MC) dosimetry software, on a 64-slice CT scanner. Simulations were performed using fixed and TCM for all patients. TCM data were extracted from the DICOM header of each reconstructed CT image. Bone structures were delineated using freehand and thresholding techniques. Structures were segmented employing both manual and automatic segmentation methods into bone-specific regions-of-interest. ROIs measurements were performed to the corresponding dose-images containing specific bone structures such as scapulae, clavicles, ribs and sternum, vertebrae and humeri. Normalized to CTDI doses were derived for all primarily irradiated bone structures and correlated to patient’s water equivalent diameter (WED). Considering the percentage of bone active marrow at various ages, absorbed doses to RBM were calculated using a) specific RBM percentage in each bone structure and b) average RBM percentage at a given age assigned to bone as a single structure in the thoracic region. Results Normalized to CTDI bone and RBM dose exhibited a good correlation (R2 = 0.7–0.8) with WED (P 0.001). Percentage RBM dose differences between the two preceding methods ranged from 0.5 to 7.5% for both fixed and automatic TCM, while mean differences for ages 0–15 years were up to 3.5%. Conclusions The current study investigates the correlation of bone and RBM absorbed doses with patient size. Size-specific normalized coefficients should be employed when assessing doses from thoracic CT protocols. When calculating RBM doses from bone absorbed doses for the thorax region, the method with average RBM percentage and the more laborious method with specific RBM distributions yield similar results with low discrepancies. However, quantitative analysis should be taken when calculating RBM in different body regions, where RBM distribution significantly varies with age. This project has received funding from the Euratom research and training programme 2014–2018 under grant agreement No. 755523.

Prognostic value of metastasis pattern for morbidity in prostate cancer measured by quantitative bone scintigraphy.

4644 Background: Quantification of bone metastases in the skeleton expressed as Bone Scan Index (BSI) and location of these are prognostic factors for mortality and morbidity in prostate cancer (PC). The purpose of this study was to identify prognostic factors for morbidity in PC based on location and extent of metastases derived from quantified bone scintigraphies (BS). Methods: Data from 107 consecutive patients with noncurable hormone-naive PC with available pretreatment 99mTc-MBP BS from the period 2003-2007 were retrospectively analyzed. BSI and location of metastases were measured from the BS using Exini Bone 1.0 (Exini AB, Sweden). Observed BSI for 8 regions was compared to the expected BSI calculated from the red bone marrow distribution. A logistic regression model for having skeletal events (SE), defined as external beam radiation for bone pain, spinal cord compression or pathological fracture at any location in the skeleton based on pre-treatment BSI, metastases distribution and PSA, was made. Results: The average BSI for the 72 patients with metastases at diagnosis was 1.063. Metastatic distribution expressed as the average BSI in these patients for each region was compared to the expected BSI of the same regions (Table). Patients with metastases to the skull had increased risk of SEs with OR: 4.2 (95% CL: 1.1-16.4, p<0.036) compared to the baseline patient with no metastases. No other regions, nor total BSI or PSA reached significance. Conclusions: PC does not metastasize randomly to the skeleton but clusters in the regions closest to the primary tumor. Patients with skull metastases have a higher risk of SEs throughout the skeleton. Very few SEs actually occurred in the skull region but skull metastases may indicate an atypical pattern of dissemination with a more aggressive phenotype of PC with more SEs. Observed and expected average BSI Skull Cervical spine Thoracic spine Lumbar spine Pelvis Upper limbs Lower limbs Thorax Observed BSI 0.057 0.012 0,129 0.127 0.471 0.041 0.079 0.147 Expected BSI 0.139* 0.036* 0,150 0.116 0.385* 0.088* 0.041* 0.108* * Different from corresponding average BSI, same region, p<0.05 t-test. No significant financial relationships to disclose.

A Cohort Study with Regard to the Risk of Haematological Malignancies in Patients treated with X-Rays for Benign Lesions in the Locomotor System: II. Estimation of Absorbed Dose in the Red Bone Marrow

A cohort study with regard to the risk of haematological malignancies was performed on about 20,000 patients who in 1950-1964 received roentgen treatment for benign conditions in the locomotor system. In order to estimate the mean absorbed red bone marrow dose the treatments were classified as concerning 10 sites (cervical spine, thoracic spine, lumbar spine, sacral region, shoulder, hip, elbow, wrist, knee and ankle). The four last-mentioned sites do not normally contain red bone marrow in adults and their contribution to the mean absorbed dose was regarded as zero. For the other 6 sites random samples consisting of 30 patients for each site were drawn from the cohort. By use of the treatment records and data from the literature on some physical parameters and red bone marrow distribution in normal adult persons, average conversion factors were calculated by which the subscribed surface dose could be converted into mean absorbed dose in red bone marrow. These conversion factors were then applied on the whole cohort and used for stratification of it according to different levels of exposure.

Bone marrow extension and pelvic bone marrow activity in alcoholic liver disease. A RES scintigraphic investigation.

Red bone marrow extension and increased central bone marrow activity were found in 21 patients with alcoholic liver disease investigated with scintigraphy of the reticuloendothelial system. The patients had no concurrent disease known to alter red bone marrow distribution. The bone marrow extension and the increased pelvic bone marrow activity may be explained as being secondary to a decreased radiocolloid uptake in the liver and could thus be a sign of decreased reticuloendothelial capacity.

Bone marrow extension and pelvic bone marrow activity in alcoholic liver disease

Red bone marrow extension and increased central bone marrow activity were found in 21 patients with alcoholic liver disease investigated with scintigraphy of the reticuloendothelial system. the patients had no concurrent disease known to alter red bone marrow distribution. the bone marrow extension and the increased pelvic bone marrow activity may be explained as being secondary to a decreased radiocolloid uptake in the liver and could thus be a sign of decreased reticuloendothelial capacity

Distribution of Red Bone Marrow

Distribution of Red Bone Marrow