Estimating radiation doses to the skin from interventional radiology procedures for a patient population with cancer.

Purpose: To estimate the peak radiation skin doses for interventional radiology cases performed at a cancer center, identify procedure types likely to result in skin doses exceeding the American College of Radiology's 3 Gy follow-up level, and determine a kerma area product (P(KA)) for use in monitoring.

Materials And Methods: A single-center retrospective study was performed to estimate doses from consecutive procedures performed during 2006. Of 6,598 procedures, 3,925 (60%) had P(KA) recorded and were included.

Possible axonal regrowth in late recovery from the minimally conscious state.

We used diffusion tensor imaging (DTI) to study 2 patients with traumatic brain injury. The first patient recovered reliable expressive language after 19 years in a minimally conscious state (MCS); the second had remained in MCS for 6 years. Comparison of white matter integrity in the patients and 20 normal subjects using histograms of apparent diffusion constants and diffusion anisotropy identified widespread altered diffusivity and decreased anisotropy in the damaged white matter.

Validation of GATE Monte Carlo simulations of the GE Advance/Discovery LS PET scanners.

The recently developed GATE (GEANT4 application for tomographic emission) Monte Carlo package, designed to simulate positron emission tomography (PET) and single photon emission computed tomography (SPECT) scanners, provides the ability to model and account for the effects of photon noncollinearity, off-axis detector penetration, detector size and response, positron range, photon scatter, and patient motion on the resolution and quality of PET images. The objective of this study is to validate a model within GATE of the General Electric (GE) Advance/Discovery Light Speed (LS) PET scanner. Our three-dimensional PET simulation model of the scanner consists of 12 096 detectors grouped into blocks, which are grouped into modules as per the vendor's specifications.

Prediction of myelotoxicity based on bone marrow radiation-absorbed dose: radioimmunotherapy studies using 90Y- and 177Lu-labeled J591 antibodies specific for prostate-specific membrane antigen.

Unlabelled: In radioimmunotherapy, myelotoxicity due to bone marrow radiation-absorbed dose is the predominant factor and frequently is the dose-limiting factor that determines the maximum tolerated dose (MTD). With (90)Y- and (131)I-labeled monoclonal antibodies, it has been reported that myelotoxicity cannot be predicted on the basis of the amount of radioactive dose administered or the bone marrow radiation-absorbed dose (BMrad), estimated using blood radioactivity concentration. As part of a phase I dose-escalation study in patients with prostate cancer with (90)Y-DOTA-J591 (DOTA = 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) ((90)Y-J591) and (177)Lu-DOTA-J591 ((177)Lu-J591), we evaluated the potential value of several factors in predicting myelotoxicity.

Pharmacokinetics and biodistribution of 111In- and 177Lu-labeled J591 antibody specific for prostate-specific membrane antigen: prediction of 90Y-J591 radiation dosimetry based on 111In or 177Lu?

Unlabelled: 111In-Labeled antibodies and peptides have been routinely used as chemical and biologic surrogates for 90Y-labeled therapeutic agents. However, recent studies have shown that there are significant differences in biodistribution between 111In- and 90Y-labeled agents. Yttrium and lutetium metals favor the +3 oxidation state, similar to indium, but there are minor differences in the solution and coordination chemistries among these metals.

Determination of immunoreactive fraction of radiolabeled monoclonal antibodies: what is an appropriate method?

Determination of the immunoreactive fraction (IF) of radiolabeled monoclonal antibodies (MAb) is essential to the understanding of the effects of radiolabeling and subsequent target-specific tumor localization. There has been generally no accepted method of determining the IF of MAbs. The conventional method is based on a radioimmunoassay technique in which the fraction of radiolabeled MAb bound to antigen under conditions of "antigen excess" is determined.

Targeted alpha particle immunotherapy for myeloid leukemia.

Unlike beta particle-emitting isotopes, alpha emitters can selectively kill individual cancer cells with a single atomic decay. HuM195, a humanized anti-CD33 monoclonal antibody, specifically targets myeloid leukemia cells and has activity against minimal disease. When labeled with the beta-emitters (131)I and (90)Y, HuM195 can eliminate large leukemic burdens in patients, but it produces prolonged myelosuppression requiring hematopoietic stem cell transplantation at high doses.