Reconstructing 3D proton dose distribution using ionoacoustics.

In proton therapy high energy protons are used to irradiate a tumor. Ideally, the delivered proton dose distribution is measured during treatment to ensure patient safety and treatment effectiveness. Here we investigate if we can use the ionoacoustic wave field to monitor the actual proton dose distribution for the two most commonly used proton accelerators; the isochronous cyclotron and the synchrocyclotron. To this end we model the acoustic field generated by the protons when irradiating a heterogeneous cancerous breast with a 89 MeV proton beam. To differentiate between the systems, idealized temporal micro-structures of the beams have been implemented. Results show that by employing model-based inversion we are able to reconstruct the 3D dose distributions from the simulated noisy pressure fields. Good results are obtained for both systems; the absolute error in the position of the maximum amplitude of the dose distribution is 5.0 mm for the isochronous cyclotron and 5.2 mm for the synchrocyclotron. In conclusion, this numerical study suggests that the ionoacoustic wave field may be used to monitor the proton dose distribution during breast cancer treatment.

[Pulmonary crackles, what does the clinician hear?]. / Craquements pulmonaires: que perçoit le clinicien ?

INTRODUCTION: The overall duration of a pulmonary crackle is usually less than 20-30 ms but psychoacoustics demonstrates that an acoustical event with a duration of less than 20-40 ms cannot be estimated in terms of pitch and duration. We pose the hypothesis that the main resonant information is contained into the breath sounds following the crackle. METHODS: Eight patients with COPD, viral pneumonia, bronchiectasis, congestive heart failure, hypoproteinemia and fibrosing alveolitis were recruited for this study. Thirty-six crackles were analyzed in time and frequency domains; 12 in each category of low, medium and high frequencies. The acoustic features of the crackles, their segments (initial deflection width, first cycle duration, two cycles duration, decay segment) and the breath sounds following the crackles were compared. RESULTS: The study confirms the differences between the three crackles categories in time and frequency domains. No statistical differences were found between the decay segments and breath sounds in each category. CONCLUSIONS: Breath sounds modified by lung tissue density could be the main resonators determining the fundamental transmission frequencies of crackle signals. Combined acoustic analysis of crackles and breath sounds could replace single analysis of isolated crackles.

[Pulmonary stethacoustic nomenclature: Why not a worldwide consensus?]. / Nomenclature stéthacoustique pulmonaire: pourquoi pas un consensus mondial?

In order to found the stethacoustic nomenclature on objective facts, we suggest to express lung sounds in a way taking first into account acoustical physics. Indeed the physicoacoustical definition of lung sounds has to take place before its psychoacoustical definition. Acoustical physics identifies only four kinds of vibrations: simple and complex periodical vibrations, transient and continuous non periodical vibrations. Lung sounds are bound to fall into one of those four categories. Phonopneumograms in time and frequency domain allow an objective classification of breath and adventitious lung sounds and introduce a simplification into the nomenclature which recognizes only four sorts of lung sounds, all of them included in these two categories: 1 degree breath sounds include normal and bronchial breath sounds, 2 degrees adventitious sounds include crackles (for every discontinuous sound) and wheezes (for every continuous sound). Objective parameters add their specific characteristics in terms of pitch, complexity, Hz-frequency, timing in the respiratory cycle and duration. The proposal of a new nomenclature is justified because it is supported by measurable physical phenomena. The solution of semantic problems should enable clinicians to progress toward a worldwide consensus.

Novel carbocyclic nucleosides containing a cyclopentyl ring. Adenosine and uridine analogues.

cis-3-Aminomethylcyclopentylmethanol (4) was used as a precursor in the synthesis of carbocyclic nucleosides containing adenine, hypoxanthine, 8-azahypoxanthine, uracil, and 5-iodouracil bases. None of these compounds had appreciable activity against eighteen viruses in the concentration ranges tested. Two of them showed a weak cytostatic activity against three tumor lines.

[Epidemiological surveillance of antibiotic resistance in a general hospital for the assessment of 'blind' antibiotics policy]. / Epidemiologische surveillance van antibioticumresistentie in een algemeen ziekenhuis ter beoordeling van 'blind' antibioticumbeleid.

A study was made of the epidemiology of gentamicin-resistant Gram-negative rods in a large general hospital over the last 12 years, and of the consequences of the presence of these bacteria for antibiotics policies, especially the use of gentamicin. Resistant bacteria were endemic at a low level: of the clinical isolates, 670 from 488 patients contained resistant bacteria, 2% of all Gram-negative rod isolates. Sporadically there were minor epidemics. Especially seriously ill, elderly patients became infected. Every year multiresistant bacteria contributed to a number of deaths. The choice of gentamicin as a drug of first, blind, choice in life-threatening infections remained justified. Continuous monitoring of Gram-negative rods is an important instrument for a preventive policy.

Prospective trial of recombinant leucocyte interferon in chronic hepatitis B: a long-term follow-up study.

Twenty-one adult patients with chronic hepatitis B and active viral replication as indicated by positivity for hepatitis B e antigen and hepatitis B virus DNA, with increased DNA polymerase levels for more than 6 months, were entered into a prospective trial of low-dose recombinant human alpha-interferon therapy. All patients were treated with 5 million units of recombinant interferon alfa-2b given subcutaneously every other day for 12 weeks. During treatment, 18 patients (86%) showed a significant reduction of DNA polymerase levels (p less than or equal to 0.001), which reached normal values in ten (48%). After 10 months' mean follow up, seven patients (33%) were hepatitis B e antigen negative and five (24%) subsequently became positive for antibodies to e antigen. By 27 months, nine patients (43%) were both hepatitis B e antigen negative and e antibody positive. Only one patient became permanently negative for hepatitis B surface antigen. One patient relapsed during the second year of follow up. Side effects necessitated withdrawal of therapy in two patients: one due to worsening thrombocytopenia after two doses of interferon (data omitted from the study results) and one due to a local reaction at the injection sites. Our data indicate that small doses of recombinant interferon alfa-2b given during a 12-week period induce a significant reduction in viral replication and approximately triple the spontaneous seroconversion rate observed in patients with chronic hepatitis B.

Prospective trial of recombinant leucocyte interferon in chronic hepatitis B: a 10-month follow-up study.

Twenty-one adult patients with chronic hepatitis B and active viral replication as indicated by the presence of hepatitis Be antigen (HBeAg), increased DNA polymerase (DNAp) and positive hepatitis B virus DNA (HBV-DNA) for more than 6 months, were entered into a prospective trial of recombinant human interferon therapy. Ten patients had chronic persistent or chronic lobular hepatitis, 8 chronic active hepatitis and 3 postnecrotic cirrhosis. All cases were treated with 5 x 10(6) units of recombinant interferon alfa-2B given subcutaneously every other day for 12 weeks. During treatment, 18 patients (86%) showed a significant reduction of DNAp levels, which reached normal values in 10 patients (48%). Viral replication was controlled over a 10-month follow-up period in 7 out of 21 patients (33%). Of these 7, five patients became HBeAg negative and HBeAb positive. HBsAg disappeared in one patient. The only serious adverse effect was thrombocytopenia in one patient in whom rapid recovery occurred when interferon was withdrawn. Treatment was also terminated in a second patient because of local reactions at the injection sites occurring after 10 weeks of therapy. Our data indicate that relatively small doses of recombinant alfa-2B interferon given during a 12-week period induce a significant reduction in viral replication and might approximately triple the spontaneous seroconversion rate observed in patients with chronic hepatitis B.

Positive 67Ga-citrate scintigraphy: vertebral, satellite lymph node and gallbladder foci in a case of gastroenteritis with salmonella.

We report a case of salmonella gastroenteritis with recurrent fever and sepsis, slight transient lumbar pain and positive 67Ga-citrate scintigraphy. The 67Ga scan made a major contribution to the positive diagnosis of a subclinical spondylodiscit and to the correct treatment leading to the disappearance of the infectious foci.