Generation of prostate IMAT plans adaptable to the inter-fractional changes of patient geometry.

We present the results of 2-Step generation of adaptable IMAT plans for prostate carcinoma cases. The 2-Step IMAT plans show clinical and dosimetric equivalence to the reference SmartArc™-generated VMAT plans. The 2-Step plans are adapted to inter-fractional changes of prostate-rectum geometry using 2-Step adaptation rules for a cohort of ten adaptation cases. The adapted 2-Step IMAT plans show statistically significant improvement (Wilcoxon 1-tail p < 0.05) of target coverage and of rectum sparing when compared to isocenter relocated plans.

Prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals.

The design, calibration, dosimetry and performance evaluation of a prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals (i.e. rats or rabbits) is discussed. The system design was guided by Monte Carlo transport calculations using MCNP-4C code. A system was built and performance evaluation was made using a 185-GBq Pu-Be neutron source. Prompt-gamma rays produced by neutron capture reactions were detected by a combination of a NaI(Tl) scintillation and a HPGe semiconductor detectors. Nitrogen and chlorine were quantified by analysis of the 10.83-MeV and 6.11-MeV peaks, respectively. Appropriate corrections for the animal body size were determined. The facility described allows the in vivo determination of protein and extracellular space in sets of experimental animals.

Atypical radionuclide scan appearance in cellulitis due to group A streptococcus.

The scintigraphic manifestations of cellulitis consist of a diffuse increase in activity in the affected soft tissues without a focal increase in activity in the bone. The radionuclide images in two children with Group A streptococcal cellulitis were atypical, as no increased activity was noted in the soft tissues. The false-negative radionuclide images in these children is attributed to the marked amount of edema present at the sites of infection.

Indium-111-labeled white blood cells: dosimetry in children.

The distribution of [111In]oxine-labeled leukocytes was studied by whole-body gamma camera imaging in nine pediatric patients. Images were obtained at approximately 24 hr after administration of the material. Organ distribution was estimated from stored data by manual region of interest assignment. Dosimetry estimates based on geometric mean and conjugate view absolute activity calculations showed close agreement in these patients. Leukocytes were distributed in liver, spleen and marrow. The mean percent uptakes +/- s.d. were: spleen, 31.2 +/- 18.3%; liver, 26.3 +/- 10.8%; and marrow, 14.2 +/- 5.7%. A significant portion (28.3 +/- 9.9%) of administered white cell activity was found outside these organs in the remainder of the body. Mean organ absorbed doses (rad/mCi) were: spleen, 115.0 +/- 84.8; liver, 13.9 +/- 7.8; marrow, 7.6 +/- 3.8; and total body 2.5 +/- 1.0. The mean organ absorbed doses (rad/dose administered) were: spleen, 13.7 +/- 10.6; liver, 1.48 +/- 0.62; marrow, 0.79 +/- 0.26; and total body, 0.28 +/- 0.09.

Recent advances in pediatric nuclear medicine.

The applications of nuclear medicine in pediatrics have grown parallel with the development of higher resolution complementary imaging modalities such as computed tomography, ultrasound, digital angiography, and magnetic resonance. The purpose of this article is to present clinically significant advances in pediatric nuclear imaging, with emphasis on newer techniques less often associated with pediatric patients.

Effect of oxygen on right ventricular performance evaluated by radionuclide angiography in two young patients with chronic lung disease.

Pulmonary hypertension is a relatively common complication of chronic lung disease in children that can cause diminished right ventricular performance (RVP) and, eventually, cor pulmonale and heart failure. Since oxygen may decrease pulmonary artery pressure in these patients, we questioned whether RVP would also improve concomitantly. We evaluated the effect of oxygen on RVP in two young hypoxemic patients by radionuclide angiography. A child with bronchopulmonary dysplasia and cor pulmonale who was not clinically in heart failure had acutely better RVP while breathing oxygen and a further improvement after continuous oxygen therapy for 1 year. In a young adult with cystic fibrosis who was suspected of being in heart failure RVP acutely improved when the FIO2 was increased. We conclude that oxygen may improve RVP in hypoxemic patients and speculate that the observation of such improvement may be valuable for the early detection of patients who can benefit from long-term oxygen therapy.

Pulmonary ventilation and perfusion studies in infants and children.

Ventilation and perfusion imaging techniques may be applied successfully to the diagnosis of many pulmonary disorders in children. These studies may be performed with relative ease and safety in all patients, even if they are unable to cooperate. The choice of radiopharmaceuticals applicable to children includes inert gases such as xenon 133 and krypton 81m as well as technetium 99m particles for perfusion and aerosol ventilation imaging. Quantitation of regional lung function is readily performed with available techniques. The indications for ventilation and perfusion lung imaging in children differ significantly from those in the adult.

Carotid endarterectomy in the community hospital. A continuing controversy.

A retrospective review of 390 carotid endarterectomies performed in two major private hospitals over 78 months by general and neurological surgeons, was conducted. The mortality was 3.1% including five fatal strokes. Permanent neurological deficit was noted in 7.2% of survivors. Use of an intraoperative shunt, or the occurrence of postoperative hypotension did not alter the morbidity. Postoperative hypertension was clearly detrimental, while those with a stable postoperative course fared best. General vascular surgeons were classified as having had additional cardiovascular training, special interest or occasional experience in vascular surgery. Neither training nor case load appeared to affect morbidity. Individual differences within groups were greater than between groups. Improvement of statistics was noted in the second 18 months. It is concluded that the best method to improve results in the moderate sized community with a mixed pool of surgeons is to promote open and ongoing peer review of indications and results of carotid endarterectomy.

Digital subtraction angiography and its application in children.

The authors explain the basic principles of this exciting new modality and focus on the special considerations of its use in children, its clinical applications, digital subtraction and radiation exposure, and digital fluorography and radiography.

Renal masses in children. An integrated imaging approach to diagnosis.

In view of the continuing technologic advancements in the development and availability of diagnostic imaging modalities, it is appropriate to assess periodically the currently accepted approaches to the evaluation of renal masses in children. The roles, advantages, and disadvantages of plain film, intravenous urography, ultrasonography, radionuclide scintigraphy, computed tomography, angiography, and magnetic resonance imaging in the approach to the evaluation of renal masses in children are discussed. An integrated imaging approach that provides the most accurate and necessary information for diagnosis and treatment is recommended.

Disparate hepatic imaging with technetium-99m sulfur colloid and disofenin in Wilson's disease.

A 10-yr-old boy presented with fulminant hepatic failure. Technetium-99m sulfur colloid images showed absent reticuloendothelial function in the liver. A [99mTc]-disofenin hepatobiliary scan visualized liver parenchyma and biliary excretion. Disparate appearance of the liver may be seen in other hepatic diseases, but should be remembered as a possible pattern in Wilson's disease.

CT of the pediatric chest.

The use of CT in the pediatric age group has been steadily increasing since the introduction of the newer generations of scanners with improved resolution and faster scan times. Though the clinical impact of CT of the chest has been less dramatic than that of the head and abdomen, the role of CT is rapidly evolving. CT of the chest has proven to be of great value in the evaluation of the mediastinum and in the detection of metastatic disease. The role of CT of the chest is expanding and further applications are to be expected.

Diagnosis of acute inflammatory conditions in children and adolescents using In-111 oxine white blood cells.

In-111 oxine labeled white cells were used to diagnose acute inflammatory conditions in 42 children and adolescents, aged 6 weeks to 19 years. In 43 scans where a clinical correlation could be made, the test had a sensitivity of 81% and a specificity of 94%. There were no adverse reactions. For children the dose of In-111 recommended is 10-12 mu Ci/kg body weight to a maximum of 500 mu Ci.

Bulk isolation in nonaqueous media of nuclei from lyophilized cells.

Intact lyophilized nuclei are obtainable from a variety of tissues, either in situ or in culture, by freezing at -156 degrees C, drying at -25 degrees C, and mechanical disassociation in glycerol at 2 degrees C. Centrifugal separation of nuclei is accomplished in an 85 : 15 by volume mixture of glycerol and 3-chloro-1,2 propanediol at 2 degrees C. The method gives homogeneous nuclear preparations in high yield with preservation of labile and water-soluble constituents.