Although peripheral blood stem cell collections (PBSC) are thought to have less tumor involvement than bone marrow (BM), the incidence of circulating tumor cells in patients with breast cancer has not been widely investigated. We prospectively investigated the incidence and viability of tumor cell involvement in PBSC and BM collections from breast cancer patients undergoing high-dose chemotherapy/hematopoietic stem cell transplantation. Paired samples of PBSC and B M from 48 patients were analyzed using an immunocytochemical technique that detects one epithelial-derived tumor cell per 5 X I O 5 mononuclear cells. lmmunostained tumor cells were detected in 9.8% (1 3/133) PBSC specimens from 9/48 (1 8.7%) patients and in 62.3% (38/61) BM specimens from 32/48 (66.7%) patients, a significantly higher rate than in PBSC (P < ,005). IGH-DOSE chemotherapy followed by autologousH marrow infusion appears to be an effective treatment for some patients with locally advanced or metastatic breast cancer.I4 However, using sensitive immunocytochemical techniques, tumor cells can be observed in histologically normal bone marrow (BM) in 20% to 45% of patients with operable disease and in 20% to 70% of patients with metastatic breast cancer.'-* As a result, many patients who have multiple bone or BM metastases have not been considered eligible for autologous BM transplantation (BMT).Recently, peripheral blood stem collections (PBSC) have been used as an alternative to BM for hematopoietic support in patients with breast cancer or hematologic malignancies who have BM Several studies examining patients with neuroblastoma and lymphoma"-I3 suggest that PBSC collections are less likely to contain tumor cells than BM and thus may provide a less contaminated source of hematopoietic stem cell support after high-dose chemotherapy.The incidence and quantity of tumor cell contamination of PBSC collections in breast cancer patients has not been widely inve~tigated.'~,'' We prospectively examined the incidence of tumor cell contamination in paired samples of PBSC and BM collections from 48 advanced-stage breast cancer patients using a highly sensitive immunocytochemical technique. To determine whether these tumor cells were capable of clonogenic growth in vitro, tumor cell-specific clonogenic assays were performed on 58 BM or PBSC collections. MATERIALS AND METHODS Patient population andparticipating centers.Patients with histologically documented locally advanced or metastatic adenocarcinoma of the breast who were enrolled on high-dose chemotherapy programs at the participating treating institutions were eligible for this study. This protocol was approved by the Institutional Review Board for Human Investigation and each patient gave written in-The geometric mean concentration of tumor cells in contaminated PBSC specimens was 0.8/1 O5 mononuclear cells (range 0.33 to 2.0/105) compared with 22.9/105 mononuclear cells in BM (range 1 to 3,000/105, P < .0001). In culture experiments, clonogenic tumor colonies grew in 21 /26 immunocytochemically po...

Until recently, for mammography Mo anode-Mo filter x-ray tube assemblies were almost exclusively used. Modern mammography units provide the possibility to employ a variety of anode-filter combinations with the aim of adapting the x-ray spectrum to compressed breast thickness and composition. The present contribution provides information on the radiation exposure of two large groups of patients (one of 1678 and one of 945 women) who were mammographed with modern x-ray equipment, and on the dosimetry necessary for the evaluation. For dosimetric purposes spectral information is essential. X-ray spectra have been determined for various anode-filter combinations from measurements with a Ge detector. Based on these spectra, conversion factors from air kerma free in air to average glandular dose (g factors) have been calculated for different anode-filter combinations, compressed breast thickness ranging from 2 to 9 cm and breast compositions varying from 0 to 100% glandular tissue. Determinations of various quantities, including entrance surface air kerma (ESAK), tube output, tube loading (TL), fraction of glandular tissue (FGL) and compressed breast thickness, were made during actual mammography. Average glandular dose (AGD) was determined using g factors corrected for tissue composition as well as g values for standard breast composition, i.e. 50% adipose tissue and 50% glandular tissue by mass. It is shown that, on average, the influence of the actual breast composition causes variations of the order of about 15%. For group 1 and group 2, the mean values of average glandular dose (using g factors corrected for tissue composition) were 1.59 and 2.07 mGy respectively. The number of exposures per woman was on average 3.4 and 3.6 respectively. The mean value of compressed breast thickness was 55.9 and 50.8 mm respectively. The mean age of group 1 was 53.6 years (for group 2 the age was not recorded). The fraction by mass of glandular tissue FGL decrease with increasing compressed breast thickness and age of patient (from 75% at 25 mm to 20% at 80 mm, and from 65% at 20 years to 30% at 75 years). For a medium-sized breast, i.e. a compressed breast thickness of 55 mm, FGL is about 35%, indicating that the standard mix (FGL = 50%) might need some modification, particularly because of additional evidence from another investigation with similar results on FGL.

No abstract

Updated E/DLP coefficients and typical values of E for UK CT, and an appreciation of factors influencing these data.

The condensed-history electron transport algorithms in the Monte Carlo code MCNP4C are derived from ITS 3.0, which is a well-validated code for coupled electron-photon simulations. This, combined with its user-friendliness and versatility, makes MCNP4C a promising code for medical physics applications. Such applications, however, require a high degree of accuracy. In this work, MCNP4C electron depth-dose distributions in water are compared with published ITS 3.0 results. The influences of voxel size, substeps and choice of electron energy indexing algorithm are investigated at incident energies between 100 keV and 20 MeV. Furthermore, previously published dose measurements for seven beta emitters are simulated. Since MCNP4C does not allow tally segmentation with the *F8 energy deposition tally, even a homogeneous phantom must be subdivided in cells to calculate the distribution of dose. The repeated interruption of the electron tracks at the cell boundaries significantly affects the electron transport. An electron track length estimator of absorbed dose is described which allows tally segmentation. In combination with the ITS electron energy indexing algorithm, this estimator appears to reproduce ITS 3.0 and experimental results well. If, however, cell boundaries are used instead of segments, or if the MCNP indexing algorithm is applied, the agreement is considerably worse.