Standing adult human phantoms based on 10th, 50th and 90th mass and height percentiles of male and female Caucasian populations

Computational anthropomorphic human phantoms are useful tools developed for the calculation of absorbed or equivalent dose to radiosensitive organs and tissues of the human body. The problem is, however, that, strictly speaking, the results can be applied only to a person who has the same anatomy as the phantom, while for a person with different body mass and/or standing height the data could be wrong. In order to improve this situation for many areas in radiological protection, this study developed 18 anthropometric standing adult human phantoms, nine models per gender, as a function of the 10th, 50th and 90th mass and height percentiles of Caucasian populations. The anthropometric target parameters for body mass, standing height and other body measures were extracted from PeopleSize, a well-known software package used in the area of ergonomics. The phantoms were developed based on the assumption of a constant body-mass index for a given mass percentile and for different heights. For a given height, increase or decrease of body mass was considered to reflect mainly the change of subcutaneous adipose tissue mass, i.e. that organ masses were not changed. Organ mass scaling as a function of height was based on information extracted from autopsy data. The methods used here were compared with those used in other studies, anatomically as well as dosimetrically. For external exposure, the results show that equivalent dose decreases with increasing body mass for organs and tissues located below the subcutaneous adipose tissue layer, such as liver, colon, stomach, etc, while for organs located at the surface, such as breasts, testes and skin, the equivalent dose increases or remains constant with increasing body mass due to weak attenuation and more scatter radiation caused by the increasing adipose tissue mass. Changes of standing height have little influence on the equivalent dose to organs and tissues from external exposure. Specific absorbed fractions (SAFs) have also been calculated with the 18 anthropometric phantoms. The results show that SAFs decrease with increasing height and increase with increasing body mass. The calculated data suggest that changes of the body mass may have a significant effect on equivalent doses, primarily for external exposure to organs and tissue located below the adipose tissue layer, while for superficial organs, for changes of height and for internal exposures the effects on equivalent dose are small to moderate.

Posture-specific phantoms representing female and male adults in Monte Carlo-based simulations for radiological protection

Does the posture of a patient have an effect on the organ and tissue absorbed doses caused by x-ray examinations? This study aims to find the answer to this question, based on Monte Carlo (MC) simulations of commonly performed x-ray examinations using adult phantoms modelled to represent humans in standing as well as in the supine posture. The recently published FASH (female adult mesh) and MASH (male adult mesh) phantoms have the standing posture. In a first step, both phantoms were updated with respect to their anatomy: glandular tissue was separated from adipose tissue in the breasts, visceral fat was separated from subcutaneous fat, cartilage was segmented in ears, nose and around the thyroid, and the mass of the right lung is now 15% greater than the left lung. The updated versions are called FASH2_sta and MASH2_sta (sta = standing). Taking into account the gravitational effects on organ position and fat distribution, supine versions of the FASH2 and the MASH2 phantoms have been developed in this study and called FASH2_sup and MASH2_sup. MC simulations of external whole-body exposure to monoenergetic photons and partial-body exposure to x-rays have been made with the standing and supine FASH2 and MASH2 phantoms. For external whole-body exposure for AP and PA projection with photon energies above 30 keV, the effective dose did not change by more than 5% when the posture changed from standing to supine or vice versa. Apart from that, the supine posture is quite rare in occupational radiation protection from whole-body exposure. However, in the x-ray diagnosis supine posture is frequently used for patients submitted to examinations. Changes of organ absorbed doses up to 60% were found for simulations of chest and abdomen radiographs if the posture changed from standing to supine or vice versa. A further increase of differences between posture-specific organ and tissue absorbed doses with increasing whole-body mass is to be expected.

FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: I. Development of the anatomy

Among computational models, voxel phantoms based on computer tomographic (CT), nuclear magnetic resonance (NMR) or colour photographic images of patients, volunteers or cadavers have become popular in recent years. Although being true to nature representations of scanned individuals, voxel phantoms have limitations, especially when walled organs have to be segmented or when volumes of organs or body tissues, like adipose, have to be changed. Additionally, the scanning of patients or volunteers is usually made in supine position, which causes a shift of internal organs towards the ribcage, a compression of the lungs and a reduction of the sagittal diameter especially in the abdominal region compared to the regular anatomy of a person in the upright position, which in turn can influence organ and tissue absorbed or equivalent dose estimates. This study applies tools developed recently in the areas of computer graphics and animated films to the creation and modelling of 3D human organs, tissues, skeletons and bodies based on polygon mesh surfaces. Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been designed using software, such as MakeHuman, Blender, Binvox and ImageJ, based on anatomical atlases, observing at the same time organ masses recommended by the International Commission on Radiological Protection for the male and female reference adult in report no 89. 113 organs, bones and tissues have been modelled in the FASH and the MASH phantoms representing locations for adults in standing posture. Most organ and tissue masses of the voxelized versions agree with corresponding data from ICRP89 within a margin of 2.6%. Comparison with the mesh-based male RPI_AM and female RPI_AF phantoms shows differences with respect to the material used, to the software and concepts applied, and to the anatomies created.

FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: II. Dosimetric calculations

Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been developed in the first part of this study using 3D animation software and anatomical atlases to replace the image-based FAX06 and the MAX06 voxel phantoms. 3D modelling methods allow for phantom development independent from medical images of patients, volunteers or cadavers. The second part of this study investigates the dosimetric implications for organ and tissue equivalent doses due to the anatomical differences between the new and the old phantoms. These differences are mainly caused by the supine position of human bodies during scanning in order to acquire digital images for voxel phantom development. Compared to an upright standing person, in image-based voxel phantoms organs are often coronally shifted towards the head and sometimes the sagittal diameter of the trunk is reduced by a gravitational change of the fat distribution. In addition, volumes of adipose and muscle tissue shielding internal organs are sometimes too small, because adaptation of organ volumes to ICRP-based organ masses often occurs at the expense of general soft tissues, such as adipose, muscle or unspecified soft tissue. These effects have dosimetric consequences, especially for partial body exposure, such as in x-ray diagnosis, but also for whole body external exposure and for internal exposure. Using the EGSnrc Monte Carlo code, internal and external exposure to photons and electrons has been simulated with both pairs of phantoms. The results show differences between organ and tissue equivalent doses for the upright standing FASH/MASH and the image-based supine FAX06/MAX06 phantoms of up to 80% for external exposure and up to 100% for internal exposure. Similar differences were found for external exposure between FASH/MASH and REGINA/REX, the reference voxel phantoms of the International Commission on Radiological Protection. Comparison of effective doses for external photon exposure showed good agreement between FASH/MASH and REGINA/REX, but large differences between FASH/MASH and the mesh-based RPI_AM and the RPI_AF phantoms, developed at the Rensselaer Polytechnic Institute (RPI).

Subcutaneous omacetaxine mepesuccinate in imatinib-resistant chronic myeloid leukemia (CML) patients (Pts) with the T315I mutation: Data from an ongoing phase II/III trial

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Background: Omacetaxine (OM), a first-in-class cetaxine shows clinical activity against Ph+ CML with a mechanism independent of tyrosine kinase inhibition. Currently available tyrosine kinase inhibitors (TKIs) have no activity against T315I. Methods: Adult Pts with T315I+ CML following TKI failure received OM induction at 1.25 mg/m2 subcutaneous (SC) twice daily (BID) for 14 days every 28 days followed by maintenance at 1.25 mg/m2 SC BID for 7 days every 28 days (maintenance after at least one induction cycle and achievement of hematologic response). Results: 66 pts (39 chronic [CP], 16 accelerated [AP] and 11 blast phase [BP]) have been enrolled. All had failed prior imatinib and 80% failed ≥2 prior TKIs. Median age is 58 yrs. Median disease duration is 58 mos. OM is well tolerated with transient myelosuppression as the primary toxicity. Grade 3/4 non-hematologic events are diarrhea (2%) and fatigue (4%). Efficacy data are available for 44 Pts. In CP Pts, the median number of cycles is 4 (1–22) with 39% having received ≥ 6 cycles of therapy; 64% of Pts have had the T315I clone reduced to below detection limits; the 2-year progression free survival is 70%. Conclusions: Omacetaxine in T315I+ CML Pts results in de-selection of the T315I clone and induces hematologic and cytogenetic responses.

[Table: see text]

[Table: see text]

Does pre-imatinib (IM) fluorescence in situ hybridization (FISH) predict myelosuppression and outcomes in chronic myeloid leukemia (CML)?

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Background: IM-associated myelosuppression occurs in 4–40% of CML patients (pts) vs. 1–16% in GIST. Selective inhibition of predominantly Philadelphia chromosome (Ph+) driven hematopoiesis may explain development of myelosuppression. In the absence of clinically applicable methods to quantitate Ph+/Ph- progenitor ratio, we hypothesized that the pre-IM percentage of BCR-ABL+ cells measured by FISH predicts myelosuppression. Methods: FISH pre-IM was available in 58 CML pts with chronic phase (CP, n=52), or advanced phase (AP, accelerated =3, blast =3) at 2 institutions. Grade >3 myelosuppression occurred < 60 days from starting IM in 9 pts (400 mg/d=6, > 600 mg/d=3), leading to dose reduction (4), discontinuation (1) or continuation same dose IM despite myelosuppression (4). Cryopreserved marrow CD34+/CD38- cells from 14 pts with (7) or without (7) post-IM myelosuppression were sorted using flow cytometry and subjected to FISH analyses. Results: Median FISH was higher for myelosuppression (90%) vs. no myelosuppression (80%) pts (p= 0.03), and in AP vs. CP (97 % vs. 80%, p=0.003). Results of FISH on CD34+/CD38- cells will be reported. Table summarizes outcomes of CP pts. Median follow-up was 14 and 45 months for myelosuppression and no myelosuppression AP pts, respectively. Myelosuppression AP pts expired (CML=2, GVHD=1); 1 after complete hematologic (CHR) and minor cytogenetic response (CTGR), 1 after partial HR, and 1 resistant disease. All 3 pts without myelosuppression achieved CHR with major CTGR, and 2 had partial molecular response. 1 died from GVHD. Conclusions: Higher FISH pre-IM identifies a group of CML pts who develop myelosuppression and are less likely to respond to IM.

[Table: see text]

No significant financial relationships to disclose.

Prognostic significance of leukopenia at the time of diagnosis in acute myeloid leukemia (AML)

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Background: In contrast to the poor prognosis associated with hyperleukocytosis, the prognostic significance of leukopenia at the time of diagnosis of AML is unknown. Methods: Single institution retrospective analysis of 225 consecutive, newly diagnosed AML patients (pts), homogeneously treated between July 1996 and February 2005; and divided into 2 groups based on presenting WBC: < 2,000/uL (30) and > 2,000/uL (195). Simultaneously obtained peripheral blood and marrow blasts were analyzed for cell surface expression of CD34, cKit, CXCR4, PCAM, VLA-2, VLA-3, VLA-4, VLA-5, and FLT3 using flow cytometry. Results: Patients’ characteristics (gender, secondary vs. de novo, and cytogenetic [CTG] risk) were comparable between the 2 groups. Leukopenic AML pts were older (median 56 vs. 53 years, p = 0.02), and had lower induction complete remission [CR] rates: 63% vs. 81% (p = 0.03) by univariate analysis. Induction mortality was 0% for leukopenic and 5% for non-leukopenic pts. In primary refractory pts, median survival was longer for leukopenic (11) vs. non-leukopenic (34) pts: 137 vs. 81 d (p = 0.026). Median follow-up was 22 mos. Event-free (EFS), disease-free (DFS), and overall survivals (OS) were lower in the leukopenic group: 12 vs. 14; 14 vs. 17; and 17 vs. 19 mos, respectively; but did not reach statistical significance. By multivariate analysis, age (p < 0.0001) and CTG risk group (p < 0.0001) were independent predictors of OS, while CTG risk group predicted RFS (p < 0.0001). The level of expression of cell surface adhesion molecules on blood and marrow blasts was comparable for the 2 groups. Conclusions: AML pts presenting with leukopenia have comparable outcomes to those presenting with normal or high WBC despite a lower likelihood of achieving remission. Leukopenic AML did not have over-expression of cell surface adhesion molecules.

No significant financial relationships to disclose.

Monitoring chronic myeloid leukemia (CML) response to tyrosine kinase inhibitors (TKI) and homoharringtonine (HHT) using peripheral blood (PB) fluorescence in situ hybridization (FISH) and quantitative RT-PCR (Q-PCR): Are bone marrow biopsies still needed?

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Background: The purpose of this study is to compare simultaneously obtained PB and bone marrow (BM) BCR-ABL FISH and Q-PCR to monitor response to TKI and HHT in CML. Methods: Between January 2005 and December 2008, 52 patients (pts) with chronic (n = 37, 80%), accelerated (n = 6, 7%), and blast phase (n = 9, 14%) CML had 112 simultaneous PB and BM FISH and Q-PCR before and/or after start of imatinib (IM, n = 27), dasatinib (n = 9), nilotinib (n = 1), bosutinib (n = 13), or HHT (n = 2) for newly diagnosed (n = 27), IM resistant (n = 20), or IM intolerant (n = 5) CML. 13 (26%) had chromosomal abnormalities in addition to the Philadelphia chromosome, and 10 (20%) had a detectable BCR-ABL mutation including the T315I in 2 pts. Results: 24 (46%) had simultaneous PB and BM FISH and/or Q-PCR measurements obtained at 1 time point, 9 (17%) at 2; 9 (17%) at 3; 10 (20%) at > 4 time points before and/or post-initiation of TKI or HHT. Excellent concordance was observed between PB and BM at all time points for both FISH (r = 0.96; p = 0.0003) and Q-PCR (r = 0.88; p= 0.0015). Correlation was not affected by the presence of additional chromosomal abnormalities, phase of the disease, treatment (TKI or HHT), or the number of prior therapies. Conclusions: FISH and Q-PCR are reliable methods to monitor CML response to TKI and HHT in patients with CML and may render the need for BM biopsy monitoring obsolete.

No significant financial relationships to disclose.

Prognostic significance of early lymphocyte recovery after post-autografting administration of GM-CSF in non-Hodgkin's lymphoma

The purpose of this study was to analyze the prognostic significance of early lymphocyte recovery after autologous SCT (ASCT) in the setting of routine post transplant administration of GM-CSF in patients with non-Hodgkin's lymphoma (NHL). This is a single institution retrospective comparative outcome analysis in a cohort of 268 relapsed chemosensitive NHL patients divided into two groups (early and late lymphocyte recovery) based on absolute lymphocyte counts (ALC) obtained on post transplant day +15 (ALC > or = 500, n=151 (56%) and ALC < 500, n=117 (44%)). Patient's characteristics were well-balanced between the two groups with regard to age, sex, preparative regimen, prior therapy, time from diagnosis to transplant and number of CD34+ cells infused. Post transplant complications were comparable in the two groups. Late lymphocyte recovery (ALC < 500 on day +15) was independently associated with a delay in platelet recovery (29 vs 21 days, P=0.0003) in patients who have not received pre-transplant rituximab. With a median follow-up of 22 months, no associations between early lymphocyte recovery and improvement of disease-free and overall survival were observed for either low- or intermediate-grade NHL. In conclusion, in this large single-centered retrospective analysis, where patients received routine post transplant GM-CSF, early lymphocyte recovery was not associated with favorable outcomes.

Dasatinib 140 mg QD compared to 70 mg BID in advanced-phase CML or Ph(+) ALL resistant or intolerant to imatinib: One-year results of CA180–035

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Background: Dasatinib, an oral multi-targeted kinase inhibitor of BCR-ABL and SRC family kinases, has been shown to be safe and effective at 70 mg BID in advanced phase CML and Ph(+) ALL resistant or intolerant to imatinib. QD and BID schedules were equipotent in Phase I which led to this dose-optimization study. Methods: In this Phase-III, open-label, prospective study, patients with imatinib-resistant or intolerant advanced phase CML or Ph(+) ALL were randomized to dasatinib 140 mg QD or 70 mg BID. The primary objective compared the major hematologic response (HR) rate between the 2 regimens. Dose escalation was allowed for inadequate response and dose reduction for drug toxicity. Results: From June 2005 through March 2006, 611 patients (56% male) were randomized (median age 55 years). 42% of patients received imatinib at doses >600 mg/d and 37% were treated for >3 y. Response rates, with a median follow-up of 6.5 mo (range <1 to 17 mo), are summarized in the table below. Median durations of HR and progression-free survival were 10.2 and 7.9 mo for the 140-mg QD regimen vs 12.3 and 11.7 mo in the 70-mg BID arm. Drug-related toxicities in 140-mg QD (n=304) vs 70-mg BID (n=305) arms, respectively, listed as all grades (grade 3–4), were: pleural effusion 16% vs 23%, P=0.024 (5% vs 6%); peripheral edema 6% vs 13%, P=0.004 (<1%/1%); pericardial effusion <1% vs 4%, P=0.012 (0% vs 1%); neutropenia 85% vs 87% (65% vs 70%); thrombocytopenia 89% vs 92% (68% vs 70%). Dose reductions (24% vs 36%, P=0.002) and interruptions (47% vs 54%, P=0.105) were required less frequently for the 140-mg QD regimen, whereas dose escalations were more prevalent (33% vs 22%, P=0.005). Conclusions: Dasatinib 140 mg QD shows comparable hematologic and cytogenetic response and a trend for improved tolerability in relation to 70 mg BID. Further follow-up is ongoing to assess the long-term benefit of these two schedules in patients with ABP-CML or Ph(+) ALL; 1-year follow-up will be presented.

[Table: see text] [Table: see text]