46 research outputs found
Reducing dose for digital cranial radiography : The increased source to the image-receptor distance approach
This investigation proposes that an increased source to the image-receptor distance (SID) technique can be used to optimize occipital frontal and lateral cranial radiographs acquired with direct digital radiography. Although cranial radiography is not performed on a routine basis, it should nonetheless be optimized to keep the dose to the patient as low as reasonably achievable, particularly because it can form part of the facial bone and sinus series. Dose measurements were acquired at various SIDs, and image quality was assessed using visual grading analysis. Statistically significant reductions in the effective dose between 19.2% and 23.9% were obtained when the SID was increased from the standard 100 to 150 cm (P ≤.05), and visual grading analysis scores indicate that image quality remained diagnostically acceptable for both projections. This investigation concludes that increasing the SID effectively optimizes occipital frontal and lateral skull radiographs. Radiology departments must be advised of the benefits of this technique with the goal of introducing an updated reference SID of 150 cm into clinical practice.Peer reviewe
Therapy reduction in patients with Down syndrome and myeloid leukemia: the international ML-DS 2006 trial
Digital chest radiography: an update on modern technology, dose containment and control of image quality
The introduction of digital radiography not only has revolutionized communication between radiologists and clinicians, but also has improved image quality and allowed for further reduction of patient exposure. However, digital radiography also poses risks, such as unnoticed increases in patient dose and suboptimum image processing that may lead to suppression of diagnostic information. Advanced processing techniques, such as temporal subtraction, dual-energy subtraction and computer-aided detection (CAD) will play an increasing role in the future and are all targeted to decrease the influence of distracting anatomic background structures and to ease the detection of focal and subtle lesions. This review summarizes the most recent technical developments with regard to new detector techniques, options for dose reduction and optimized image processing. It explains the meaning of the exposure indicator or the dose reference level as tools for the radiologist to control the dose. It also provides an overview over the multitude of studies conducted in recent years to evaluate the options of these new developments to realize the principle of ALARA. The focus of the review is hereby on adult applications, the relationship between dose and image quality and the differences between the various detector systems
Increasing source to image distance for AP pelvis imaging – impact on radiation dose and image quality
Aim: A quantative primary study to determine whether increasing source to image distance (SID), with
and without the use of automatic exposure control (AEC) for antero-posterior (AP) pelvis imaging, reduces
dose whilst still producing an image of diagnostic quality.
Methods: Using a computed radiography (CR) system, an anthropomorphic pelvic phantom was positioned
for an AP examination using the table bucky. SID was initially set at 110 cm, with tube potential set
at a constant 75 kVp, with two outer chambers selected and a fine focal spot of 0.6 mm. SID was then
varied from 90 cm to 140 cm with two exposures made at each 5 cm interval, one using the AEC and
another with a constant 16 mAs derived from the initial exposure. Effective dose (E) and entrance surface
dose (ESD) were calculated for each acquisition. Seven experienced observers blindly graded image
quality using a 5-point Likert scale and 2 Alternative Forced Choice software. Signal-to-Noise Ratio (SNR)
was calculated for comparison. For each acquisition, femoral head diameter was also measured for
magnification indication.
Results: Results demonstrated that when increasing SID from 110 cm to 140 cm, both E and ESD reduced
by 3.7% and 17.3% respectively when using AEC and 50.13% and 41.79% respectively, when the constant
mAs was used. No significant statistical (T-test) difference (p ¼ 0.967) between image quality was
detected when increasing SID, with an intra-observer correlation of 0.77 (95% confidence level). SNR
reduced slightly for both AEC (38%) and no AEC (36%) with increasing SID.
Conclusion: For CR, increasing SID significantly reduces both E and ESD for AP pelvis imaging without
adversely affecting image quality
Abwägen von Dosisbedarf und Bildqualität in der digitalen Radiographie
Projection radiography is in an advanced stage of progressive transition from conventional screen-film imaging to digital image acquisition modalities. The radiographic technique, including examination parameters such as tube voltage, tube current and filtration has frequently been adopted from screen-film technology. Digital systems, however, are characterized by their flexibility as the dose can be reduced at the expense of image quality and vice versa. The imaging parameters need to be individually optimized according to the best performance of a system. The traditional means of dose adjustment, such as positioning and collimation, are as valid for digital techniques as they were for conventional techniques. Digital techniques increasingly offer options for dose reduction. At the same time there is a risk to accidentally substantially increase patient dose due to the lack of visual control. Therefore, the implementation of dose indicators and dose monitoring is mandatory for digital radiography. The use of image quality classes according to the dose requirements of given clinical indications are a further step towards modern radiation protectio
Expression of Skp2 and p27KIP1 in naevi and malignant melanoma of the skin and its relation to clinical outcome
Skp2 (S-phase kinase associated protein 2)
controls progression from G- to S-phase by promoting
the proteolysis of the cyclin dependent kinase inhibitor
p27KIP1. Despite the fact that a p27KIP1 decrease has
been documented in melanoma progression, the role of
Skp2 in these tumours is unknown. We therefore
examined by immunohistochemistry the expression of
Skp2, p27KIP1 and Ki-67 in 10 naevi (Ns), 15
superficial spreading melanomas (SSMs), 10 nodular
melanomas (NMs) and 14 melanoma metastases (Ms).
Nuclear Skp2 expression augmented with increasing
malignancy (Ns: 1.4%, SSMs: 5.6%, NMs: 17.3%, Ms:
19.1%). In all tumours nuclear Skp2 expression
correlated with Ki-67 (p=0.024) and inversely with
p27KIP1 (p=0.007). A cytoplasmic reaction for Skp2
was also observed in most tumours and its expression
decreased from Ns (12.3%) to SSMs (7.9%) and NMs
(4.5%). In contrast, Ms showed an increase of
cytoplasmic Skp2 (11.9%) that correlated with its
nuclear expression (p=0.016). While nuclear Skp2
expression correlated with the pT-level (p=0.023), Clarklevel
(p=0.023) and Breslow index (p=0.019), the
cytoplasmic Skp2 expression might be of biological
significance only in NMs since it correlated with tumour
depth (p=0.02) and pT-level (p=0.025). Our data
suggests that Skp2 could contribute to melanoma progression. This is further highlighted by the fact that
vertical growth phase (VGP) melanomas show
significant higher nuclear Skp2 expressions when
compared with the harmless radial growth phase (RGP)
(p=0.047). Also nuclear Skp2 expression correlates with
a reduced survival time (p=0.025) in melanoma