Patient dose and associated exposure parameters in pelvic x-ray examinations: dependence on radiographic system.

Technological differences between computed radiography (CR) and digital radiography (DR) systems can influence patient doses and exposure parameters in pelvic x-ray examinations. The presence of radiosensitive organs in the pelvic region underscores the need to optimize these parameters for both CR and DR systems. This prospective study aimed to compare the patient doses and exposure parameters for adult patients undergoing pelvic x-ray examinations using CR and DR systems, based on data from Sri Lanka.

Towards the establishment of national diagnostic reference levels for abdomen, KUB, and lumbar spine x-ray examinations in Sri Lanka: a multi-centric study.

Diagnostic reference levels (DRLs) and achievable doses (ADs) provide guidance to optimise radiation doses for patients undergoing medical imaging procedures. This multi-centre study aimed to compare institutional DRLs (IDRLs) across hospitals, propose ADs and multi-centric DRLs (MCDRLs) for four common x-ray examinations in Sri Lanka, and assess the potential for dose reduction. A prospective cross-sectional study of 894 adult patients referred for abdomen anteroposterior (AP), kidney-ureter-bladder (KUB) AP, lumbar spine AP, and lumbar spine lateral (LAT) x-ray examinations was conducted.

Towards the establishment of national diagnostic reference levels for chest x-ray examinations in Sri Lanka: a multi-centric study.

The establishment of diagnostic reference levels (DRLs) is an effective tool for optimising radiation doses delivered to patients during medical imaging procedures. This study aimed to compare the institutional DRLs (IDRLs) and propose a multi-centric diagnostic reference level (MCDRL) for chest x-ray examinations in adult patients in Sri Lanka. A prospective cross-sectional study was conducted with 1091 adult patients across six major tertiary care hospitals.

Evaluation of patient doses for routine digital radiography procedures toward establishing an institutional diagnostic reference levels: A case study in Sri Lanka.

The present study was conducted as part of a comprehensive work to establish National Diagnostic Reference Levels (NDRLs) in Sri Lanka for the first time. DRLs can be used as an effective optimization tool for identifying unusually high or low patient doses during X-ray examinations. This study aims to propose institutional DRLs (IDRLs) by measuring the kerma-area product (KAP) of adult patients undergoing routine projection X-ray examinations.

A1 reduction in intact cyanobacterial photosystem I particles studied by time-resolved step-scan Fourier transform infrared difference spectroscopy and isotope labeling.

Time-resolved step-scan Fourier transform infrared (FTIR) difference spectroscopy, with 5 mus time resolution, has been used to produce P700(+)A(1)(-)/P700A(1) FTIR difference spectra in intact photosystem I particles from Synechococcus sp. 7002 and Synechocystis sp. 6803 at 77 K.

Mutation of the putative hydrogen-bond donor to P700 of photosystem I.

The primary electron donor of photosystem I (PS1), called P(700), is a heterodimer of chlorophyll (Chl) a and a'. The crystal structure of photosystem I reveals that the chlorophyll a' (P(A)) could be hydrogen-bonded to the protein via a threonine residue, while the chlorophyll a (P(B)) does not have such a hydrogen bond. To investigate the influence of this hydrogen bond on P(700), PsaA-Thr739 was converted to alanine to remove the H-bond to the 13(1)-keto group of the chlorophyll a' in Chlamydomonas reinhardtii.

FTIR difference spectroscopy in combination with isotope labeling for identification of the carbonyl modes of P700 and P700+ in photosystem I.

Room temperature, light induced (P700(+)-P700) Fourier transform infrared (FTIR) difference spectra have been obtained using photosystem I (PS I) particles from Synechocystis sp. PCC 6803 that are unlabeled, uniformly (2)H labeled, and uniformly (15)N labeled. Spectra were also obtained for PS I particles that had been extensively washed and incubated in D(2)O.

Photo-oxidation of P740, the primary electron donor in photosystem I from Acaryochloris marina.

Fourier transform infrared spectroscopy (FTIR) difference spectroscopy in combination with deuterium exchange experiments has been used to study the photo-oxidation of P740, the primary electron donor in photosystem I from Acaryochloris marina. Comparison of (P740(+)-P740) and (P700(+)-P700) FTIR difference spectra show that P700 and P740 share many structural similarities. However, there are several distinct differences also: 1), The (P740(+)-P740) FTIR difference spectrum is significantly altered upon proton exchange, considerably more so than the (P700(+)-P700) FTIR difference spectrum.

Mutation induced modulation of hydrogen bonding to P700 studied using FTIR difference spectroscopy.

Site-directed mutagenesis in combination with Fourier transform infrared difference spectroscopy has been used to study how hydrogen bonding modulates the electronic and physical organization of P700, the primary electron donor in photosystem I. Wild-type PS I particles from Chlamydomonas reinhardtii and a mutant in which ThrA739 is changed to alanine [TA(A739) mutant] were studied. ThrA739 is thought to provide a hydrogen bond to the chlorophyll-a' molecule of P700 (the two chlorophylls of P700 (P700(+)) will be called P(A) and P(B) (P(A)(+) and P(B)(+))).