Bremsstrahlung parameters of praseodymium-142 in different human tissues: a dosimetric perspective for 142Pr radionuclide therapy

Objective

Praseodymium-142 [T _1/2?=?19.12?h, $ E_{\beta^{-}}$ ?=?2.162?MeV (96.3%), E???=?1575?keV (3.7%)] is one of the ¹⁴¹Pr radioisotopes. Many studies have been attempted to assess the significance of usage ¹⁴²Pr in radionuclide therapy. In many studies, the dosimetric parameters of ¹⁴²Pr sources were calculated by modeling ¹⁴²Pr sources in the water phantom and scoring the energy deposited around it. However, the medical dosimetry calculations in water phantom consider Bremsstrahlung production, raising the question: ??How important is to simulate human tissues instead of using water phantom??? This study answers these questions by estimation of ¹⁴²Pr Bremsstrahlung parameters.

Methods

The Bremsstrahlung parameters of ¹⁴²Pr as therapeutic beta nuclides in different human tissues (adipose, blood, brain, breast, cell nucleus, eye lens, gastrointestinal tract, heart, kidney, liver, lung deflated, lymph, muscle, ovary, pancreas, cartilage, red marrow, spongiosa, yellow marrow, skin, spleen, testis, thyroid and different skeleton bones) were calculated by extending the national council for radiation protection model. The specific Bremsstrahlung constant (?? _Br), probability of energy loss by beta during Bremsstrahlung emission (P _Br) and Bremsstrahlung activity (A _release)_Br were estimated. It should be mentioned that Monte Carlo simulation was used for estimation of ¹⁴²Pr Bremsstrahlung activity based on the element compositions of different human tissues and the calculated exposures from the anthropomorphic phantoms.

Results

?? _Br for yellow marrow was smallest amount (1.1962?×?10^?3 C/kg-cm²/MBq-h) compared to the other tissues and highest for cortical bone (2.4764?×?10^?3 C/kg-cm²/MBq-h), and, overall, ?? _Br for skeletal tissues were greater than other tissues. In addition, ?? _Br breast was 1.8261?×?10^?3 C/kg-cm²/MBq-h which was greater than sacrum and spongiosa bones. Moreover, according to (A _release)_Br of ¹⁴²Pr, the patients receiving ¹⁴²Pr do not have to be hospitalized for radiation precautions and the Bremsstrahlung production does not prevent the therapy for outpatients.

Conclusion

However, modeling ¹⁴²Pr source in water phantom for simulation of ¹⁴²Pr source in soft tissues could be acceptable due to similarity of ?? _Br in water and soft tissues; this approximation is a gross computation in the mediums encompassing high atomic numbers. These data may be practical in the investigation of Bremsstrahlung absorbed dose where ¹⁴²Pr is involved in radionuclide therapy.     

Malakoplakia of colon in a child with celiac disease and chronic granulomatous disease.

Malakoplakia is a rare pseudotumoral inflammatory disease known to affect immunocompromised subjects. We report a 4-year-old boy with malakoplakia of colon who was diagnosed with celiac disease in late infancy; despite aggressive nutritional and medical management for celiac disease, symptoms did not resolve. His nitro-blue-tetrazolium test was compatible with chronic granulomatous disease. In colonic biopsy Michaelis-Gutmann bodies were seen.     

Comparison of the Accuracy and Reproducibility of Focused Abdominal Sonography for Trauma Performed by Emergency Medicine and Radiology Residents

We compared the diagnostic accuracy of emergency medicine residents (EMRs) and radiology residents (RRs) in performing focused abdominal sonography for trauma (FAST). The cohort in this prospective study comprised 200 unstable patients (163 males and 37 females; mean ± standard deviation of age, 34.3 ± 16.4 y) who presented with trauma. These patients were evaluated using FAST, first by EMRs and subsequently by RRs. Patients with positive FAST results underwent further diagnostic procedures such as computed tomography, diagnostic peritoneal lavage and laparotomy. Those with negative FAST results underwent clinical follow-up for 72 h until their condition deteriorated or they were discharged. Sensitivity, specificity, positive and negative predictive values and accuracy in evaluating free intraperitoneal fluid were 80%, 95%, 57%, 98% and 94% when FAST was performed by EMRs and 86%, 95%, 59%, 98% and 94% when FAST was performed by RRs. The level of agreement between EMRs and RRs was moderate (κ = 0.525). FAST is a useful screening tool for initial assessment of free abdominal fluid in patients with trauma. Our results indicate that EMRs can perform sonography on trauma patients as successfully as RRs.     

Endogenous animal models of intracranial aneurysm development: a review

Neurosurgical Review - The pathogenesis and natural history of intracranial aneurysm (IA) remains poorly understood. To this end, animal models with induced cerebral vessel lesions mimicking human...     

Nanocarriers for nuclear imaging and radiotherapy of cancer

Several nanoscale carriers (nanoparticles, liposomes, water-soluble polymers, micelles and dendrimers) have been developed for targeted delivery of cancer diagnostic and therapeutic agents. These carriers can selectively target cancer sites and carry large payloads, thereby improving cancer detection and therapy effectiveness. Further, the combination of newer nuclear imaging techniques providing high sensitivity and spatial resolution such as dual modality imaging with positron emission tomography/computed tomography (PET/CT) and use of nanoscale devices to carry diagnostic and therapeutic radionuclides with high target specificity can enable more accurate detection, staging and therapy planning of cancer. The successful clinical applications of radiolabeled monoclonal antibodies for cancer detection and therapy bode well for the future of nanoscale carrier systems in clinical oncology. Several radiolabeled multifunctional nanocarriers have been effective in detecting and treating cancer in animal models. Nonetheless, further preclinical, clinical and long-term toxicity studies will be required to translate this technology to the care of patients with cancer. The objective of this review is to present a brief but comprehensive overview of the various nuclear imaging techniques and the use of nanocarriers to deliver radionuclides for the diagnosis and therapy of cancer.     

Cicatricial conjunctival inflammation with trichiasis as the presenting feature of Wegener granulomatosis

Wegener granulomatosis has a variety of uncommon initial presentations. Although conjunctival involvement in this condition is rare, the diagnosis of Wegener granulomatosis should be suspected when the conjunctival inflammation is recurrent and not typical of other conjunctival inflammatory conditions.     

Predictive value of human leucocyte antigen epitope matching using HLAMatchmaker for graft outcomes in a predominantly African-American renal transplant cohort

The HLAMatchmaker program is based on the donor/recipient comparison of the polymorphic triplet amino-acid sequences of the antibody-accessible regions on the human leucocyte antigen (HLA) molecule. The previous reports on its predictive value for renal allograft outcomes are conflicting. We conducted a retrospective study in a predominantly African-American (AA) cohort (N = 101, 94% AA). HLA typing was performed by molecular methods and triplet matching using HLAMatchmaker. Study end points included graft survival and incidence of acute rejection. The relationship between the number of triplet mismatches (TMM) and the degree of HLA antigen MM was evaluated using Pearson's correlation coefficient. Logistic regression models were used to examine the association between triplet matching and the study end points. Kaplan-Meier and Cox proportional hazard models were used for graft survival analysis. The strongest relationship between the number of TMM and HLA antigen MM was observed for HLA-DQ (r = 0.88). The association between triplet matching at HLA-A, -B, -DR and -DRw HLA loci and the study end points was not statistically significant. However, after grouping, the unadjusted estimates of graft survival for those with more than 10 Class I TMM were significantly worse than the others (p = 0.03). Adjusting for the effect of donor source, recipient characteristics and the immunosuppressive regimen did not change this association (hazard ratio = 0.2, confidence interval = 0.04-1.1). We conclude that triplet matching using HLAMatchmaker can provide useful prognostic information in kidney transplantation and that more than 10 donor/recipient Class I HLA TMM is predictive of worse graft outcome.     

Comparison of urinary proteins in calcium stone formers and healthy individuals: a case-control study

OBJECTIVE: This study aimed at comparing the urinary protein levels in calcium stone formers with those of healthy individuals. PATIENTS AND METHODS: From January 2002 until June 2004, 100 calcium stone formers (mean age 38.6 +/- 10.3 years), who had at least two episodes of calcium stone formation, were compared with 100 healthy individuals (mean age 33.8 +/- 9.7 years). Their 24-hour urinary protein levels, using SDS-PAGE, were measured. RESULTS: The mean 24-hour urinary Tamm-Horsfall protein (THP) levels were 3.3 +/- 0.8 mg in the case group and 4.6 +/- 1.9 mg in the controls, and the difference was not statistically significant (p = 0.53). However, the THP levels in individuals with and without bacteriuria were significantly different (15.8 +/- 3.3 mg vs. 2.6 +/- 1.0 mg, p = 0.0001). The mean 24-hour urinary albumin concentrations were 163.31 +/- 15.1 mg in the case group and 74.26 +/- 4.6 mg in the controls. The mean 24-hour urinary transferrin levels were 8.09 +/- 2.7 mg in the case group and 0.40 +/- 0.3 mg in the controls. The differences were statistically significant for both albumin and transferrin (p < 0.0001 and p = 0.0063, respectively). There were no significant differences in any other mean urinary protein concentrations between cases and controls. CONCLUSIONS: The THP level in the urine of stone formers is not quantitatively different from that of healthy individuals, but it increases in association with bacteriuria. Albumin and transferrin may play a presumptive role in stone formation.     

Troponin utilization in patients presenting with atrial fibrillation/flutter to the emergency department: retrospective chart review

Background

There are few recommendations about the use of cardiac markers in the investigation and management of atrial fibrillation/flutter. Currently, it is unknown how many patients with atrial fibrillation/flutter undergo troponin testing, and how positive troponin results are managed in the emergency department. We sought to look at the emergency department troponin utilization patterns.

Methods

We performed a retrospective chart review of patients with atrial fibrillation/flutter presenting to the emergency department at three centers. Outcome measures included the rates of troponins ordered by emergency doctors, number of positive troponins, and those with positive troponins treated as acute coronary syndrome (ACS) by consulting services.

Results

Four hundred fifty-one charts were reviewed. A total of 388 (86%) of the patients had troponins ordered, 13.7% had positive results, and 4.9% were treated for ACS.

Conclusions

Troponin tests are ordered in a high percentage of patients with atrial fibrillation/flutter presenting to emergency departments. Five percent of our total patient cohort was diagnosed as having acute coronary syndrome by consulting services.