Development of a neonate X-ray phantom for 2D imaging applications using single-tone inkjet printing

PURPOSE

Inkjet printers can be used to fabricate anthropomorphic phantoms by the use of iodine-doped ink. However, challenges persist in implementing this technique. The calibration from grayscale to ink density is complex and time-consuming. The purpose of this work is to develop a printing methodology that requires a simpler calibration and is less dependent on printer characteristics to produce the desired range of x-ray attenuation values.

METHODS

Conventional grayscale printing was substituted by single-tone printing; that is, the superposition of pure black layers of iodinated ink. Printing was performed with a consumer-grade inkjet printer using ink made of potassium-iodide (KI) dissolved in water at 1 g/ml. A calibration for the attenuation of ink was measured using a commercial x-ray system at 70 kVp. A neonate radiograph obtained at 70 kVp served as an anatomical model. The attenuation map of the neonate radiograph was processed into a series of single-tone images. Single-tone images were printed, stacked, and imaged at 70 kVp. The phantom was evaluated by comparing attenuation values between the printed phantom and the original radiograph; attenuation maps were compared using the structural similarity index measure (SSIM), while attenuation histograms were compared using the Kullback-Leibler (KL) divergence. A region of interest (ROI)-based analysis was also performed, where the attenuation distribution within given ROIs was compared between phantom and patient. The phantom sharpness was evaluated in terms of modulation transfer function (MTF) estimates and signal spread profiles of high spatial resolution features in the image.

RESULTS

The printed phantom required 36 pages. The printing queue was automated and it took about 2 h to print the phantom. The radiograph of the printed phantom demonstrated a close resemblance to the original neonate radiograph. The SSIM of the phantom with respect to that of the patient was 0.53. Both patient and phantom attenuation histograms followed similar distributions, and the KL divergence between such histograms was 0.20. The ROI-based analysis showed that the largest deviations from patient attenuation values were observed at the higher and lower ends of the attenuation range. The limiting resolution of the proposed methodology was about 1 mm.

CONCLUSION

A methodology to generate a neonate phantom for 2D imaging applications, using single-tone printing, was developed. This method only requires a single-value calibration and required less than 2 h to print a complete phantom.

Method of determining geometric patient size surrogates using localizer images in CT

Purpose

Size‐specific dose estimates (SSDE) requires accurate estimates of patient size surrogates. AAPM Report 204 shows that the SSDE is the product of CTDIvol and a scaling factor, the normalized dose coefficient (NDC) which depends on patient size surrogates for CT axial images. However, SSDE can be determined from CT localizer prior to CT scanning. AAPM Report 220 charges that a magnification correction is needed for geometric patient size‐surrogates. In this study, we demonstrate a novel “model‐based” magnification correction on patient data.

Methods

573 patient scans obtained from a clinical CT system including 229 adult abdomen, 284 adult chest, 48 pediatric abdomen, and 12 pediatric chest exams. LAT and AP dimensions were extracted from CT localizers using a threshold extraction method (the ACR DIR). The model‐based magnification correction was applied to the AP and LAT dimensions extracted using the ACR DIR. NDC was calculated using the effective diameter for the ACR DIR only, the model‐based localizer‐based and axial‐based approaches. The LAT and AP dimensions were extracted from the “gold” standard CT axial scans. Outliers are defined as points outside the 95% confidence intervals and were analyzed.

Results

NDC estimates for the localizer‐based model‐based approach had an excellent correlation (R² = 0.92) with the gold standard approach. The effective diameter for ACR DIR and model‐based approaches are 8.0% and 1.0% greater than the gold standard respectively. Outliers were determined to be primarily patient truncation, with arms down or with devices. ACR DIR size extraction method fails for bariatric patients where the threshold is too high and some of their anatomy was included in the CT couch, and small patients due to the CT couch being included in the size measurement.

Conclusion

The model‐based magnification method gives an accurate estimate of patient size surrogates extracted from CT localizers that are needed for calculating NDC to achieve accurate SSDE.

Prototype system for interventional dual-energy subtraction angiography

Dual-energy subtraction angiography (DESA) using fast kV switching has received attention for its potential to reduce misregistration artifacts in thoracic and abdominal imaging where patient motion is difficult to control; however, commercial interventional solutions are not currently available. The purpose of this work was to adapt an x-ray angiography system for 2D and 3D DESA. The platform for the dual-energy prototype was a commercially available x-ray angiography system with a flat panel detector and an 80 kW x-ray tube. Fast kV switching was implemented using custom x-ray tube control software that follows a user-defined switching program during a rotational acquisition. Measurements made with a high temporal resolution kV meter were used to calibrate the relationship between the requested and achieved kV and pulse width. To enable practical 2D and 3D imaging experiments, an automatic exposure control algorithm was developed to estimate patient thickness and select a dual-energy switching technique (kV and ms switching) that delivers a user-specified task CNR at the minimum air kerma to the interventional reference point. An XCAT-based simulation study conducted to evaluate low and high energy image registration for the scenario of 30-60 frame/s pulmonary angiography with respiratory motion found normalized RMSE values ranging from 0.16% to 1.06% in tissue-subtracted DESA images, depending on respiratory phase and frame rate. Initial imaging in a porcine model with a 60 kV, 10 ms, 325 mA / 120 kV, 3.2 ms, 325 mA switching technique demonstrated an ability to form tissue-subtracted images from a single contrast-enhanced acquisition.

Evaluation of AAPM Reports 204 and 220: Estimation of effective diameter, water-equivalent diameter, and ellipticity ratios for chest, abdomen, pelvis, and head CT scans

Purpose

To confirm AAPM Reports 204/220 and provide data for the future expansion of these reports by: (a) presenting the first large‐scale confirmation of the reports using clinical data, (b) providing the community with size surrogate data for the head region which was not provided in the original reports, and additionally providing the measurements of patient ellipticity ratio for different body regions.

Method

A total of 884 routine scans were included in our analysis including data from the head, thorax, abdomen, and pelvis for adults and pediatrics. We calculated the ellipticity ratio and all of the size surrogates presented in AAPM Reports 204/220. We correlated the purely geometric‐based metrics with the “gold standard” water‐equivalent diameter (D_W).

Results

Our results and AAPM Reports 204/220 agree within our data's 95% confidence intervals. Outliers to the AAPM reports’ methods were caused by excess gas in the GI tract, exceptionally low BMI, and cranial metaphyseal dysplasia. For the head, we show lower correlation (R² = 0.812) between effective diameter and D_W relative to other body regions. The ellipticity ratio of the shoulder region was the highest at 2.28 ± 0.22 and the head the smallest at 0.85 ± 0.08. The abdomen pelvis, chest, thorax, and abdomen regions all had ellipticity values near 1.5.

Conclusion

We confirmed AAPM reports 204/220 using clinical data and identified patient conditions causing discrepancies. We presented new size surrogate data for the head region and for the first time presented ellipticity data for all regions. Future automatic exposure control characterization should include ellipticity information.

Molecular analyses of a repetitive DNA sequence in wheat (Triticum aestivum L.)

A repetitive sequence designated WE35 was isolated from wheat genomic DNA. This sequence consists of a 320-bp repeat unit and represents approximately 0.002% of the total wheat DNA. It is unidirectionally distributed either continuously or discretely in the genome. Ladder-like banding patterns were observed in Southern blots when the wheat genomic DNA was restricted with endonuclease enzymes EcoRI, HincII, NciI, and NdeI, which is characteristic for tandemly organized sequences. Two DNA fragments in p451 were frequently associated with the WE35 repetitive unit in a majority of lambda wheat genomic clones. A 475-bp fragment homologous to the 5'-end long terminal repeat (LTR) of cereal retroelements was also found in some lambda wheat genomic clones containing the repetitive unit. Physical mapping by fluorescence in situ hybridization (FISH) indicated that one pair of wheat chromosomes could be specifically detected with the WE35 positive probe p551. WE35 can be considered a chromosome-specific repetitive sequence. This repetitive unit could be used as a molecular marker for genetic, phylogenetic, and evolutionary studies in the tribe Triticeae.

Imported African tick bite fever: a case report

We describe a patient with African tick-bite fever who acquired his infection while visiting rural areas of South Africa and then became sick after returning to the United States. The dominant clinical feature of his illness was the presence of multiple, ulcerated lesions (tache noires). Physicians in the United States and other non-African countries who see travelers returning from southern parts of Africa who give a history of recent tick bite and/or present with multiple, crusted or vesicular skin lesions should be alert to this diagnosis and institute treatment with doxycycline.

Follicular mucinosis as a presenting sign of acute myeloblastic leukemia

Follicular mucinosis is often associated with mycosis fungoides and has been rarely observed to occur with other neoplastic and inflammatory conditions. We describe a 60-year-old patient with follicular mucinosis who later developed acute myelogenous leukemia. This is the first reported case of follicular mucinosis as a presenting sign of acute myeloblastic leukemia in the absence of mycosis fungoides or leukemia cutis.

The great imitator: Rocky Mountain spotted fever occurring after hospitalization for unrelated illnesses

We describe two patients who had Rocky Mountain spotted fever after they were admitted to the hospital for emergency and elective surgical procedures. We initially thought one patient had a hospital-acquired infection; the correct diagnosis was deduced from epidemiologic clues elicited by consultants. These two cases were also unusual in that one patient had a recurrent rash after an abbreviated course of low-dose doxycycline therapy and the other patient had transient and self-limiting postinfectious polyneuropathy. These cases illustrate that community-acquired infection with Rickettsia rickettsii can occur simultaneously with other disease processes and sometimes mimic a nosocomial infection.

Venous ulcers

Successful therapy of venous ulcers combines local wound treatment modalities and ambulatory hemodynamic support to control the underlying disease. Compression bandaging reduces or eliminates edema, and a moist wound environment not only debrides necrotic tissue but also aids development of granulation tissue, a prerequisite for epidermal repair. We have occluded chronic wounds, known to be heavily colonized, with a hydrocolloid dressing for up to 7 days and found that soft-tissue infections occurred in only 1% of all dressing changes in our clinic, compared with 6.5% generally reported in the literature. In venous ulcers, resident bacteria may be beneficial in that their proteolytic activity assists with autolysis of fibrinopurulent wound exudate. The importance of lysing fibrin and reducing the number of existing fibrin "cuffs," thereby improving local tissue oxygenation and nutrient/waste exchange, is not completely understood; however, this phenomenon, in part, may explain the excellent clinical results obtained with one type of hydrocolloid dressing (DuoDERM), which has been shown to lyse fibrin more effectively than other types of moisture-retentive and hydrocolloid dressings.

Atypical presentation of inflammatory bowel disease in the elderly

Despite multiple invasive diagnostic procedures including exploratory laparotomy and surgical resection, our patient's diagnosis remained an enigma. However, given the clinical scenario and the documented PG, a trial of steroids was warranted. The patient has fared well since her treatment, with resolution of all her symptoms. We feel confident that her disease process is most consistent with, and is most likely, Crohn's disease. There are several lessons to be learned from this case: 1) Inflammatory bowel disease can present at any age and belongs in a clinician's differential diagnosis of fever and diarrhea. 2) Failure to consider IBD in an elderly patient may lead to significant delay in diagnosis, and may expose the patient to unnecessary and sometimes dangerous intervention. 3) IBD in the elderly generally follows the same clinical patterns seen in younger patients. 4) Appropriate therapy can lead to prompt control or even resolution of the signs and symptoms of IBD.

Management of chronic and problem lower extremity wounds

With simple, inexpensive therapy, virtually all venous ulcers heal without the need for hospitalization, skin grafting, growth factors, hyperbaric oxygen, or debilitating bed rest. Although the future promises to yield a greater understanding about the nature of these wounds and ways to treat them, one can benefit the vast majority of patients with available technology. Few therapeutic experiences are as gratifying as healing a patient's debilitating chronic wound.

Treatment of leg ulcers

Leg ulcers represent the most common chronic wound in our population. This devastating problem often cripples patients, many of whom are in the prime of their working years. The resulting morbidity and financial cost are extraordinary. Fortunately, with the right approach, the vast majority heal with simple ambulatory outpatient therapy. The essential requirements for treating leg ulcers include a thorough understanding of lower extremity anatomy, vascular hemodynamics, and the management of trophic and inflammatory skin changes.

Treatment of lymphangioma circumscriptum with tunable dye laser

We present the case of a patient with lymphangioma circumscriptum that was successfully treated with a flashlamp pulsed dye laser. Dermatologists are aware of the use of the pulsed dye laser for the treatment of port-wine stains and other vascular lesions. This case report illustrates the usefulness of the pulsed dye laser for the treatment of another common dermatologic condition.

Merkel cell tumor

A case of a rapidly growing Merkel cell tumor occurring on the lower extremity in an 83-year-old woman is reported. A brief review of the clinical characteristics of this tumor as well as its immunohistochemical and ultrastructural features are presented.

Letterer-Siwe disease in an adult

Letterer-Siwe disease, a proliferative disorder of Langerhans' cells, usually affects children during the first year of life. A 67-year-old woman is described here whose initial manifestation was a characteristic skin eruption. The clinical, pathologic, and ultrastructural features of Letterer-Siwe disease are reviewed and their role in diagnosis discussed.

Primary lymphocutaneous Nocardia brasiliensis infection

We report a rare case of primary lymphocutaneous Nocardia brasiliensis infection occurring in an elderly diabetic man maintained on long-term therapy with prednisone. The mode of inoculation was that of a puncture wound caused by a contaminated needle that occurred one month prior to the development of the clinically apparent infection. The course of this patient's infection was protracted and required two surgical procedures and several months of antibiotic therapy. A review of 15 previously reported cases is presented as well as a discussion of appropriate medical therapy.

Familial aggregation of melanoma, basal cell carcinoma, and gastric adenocarcinoma

A family with four cases of melanoma, seven cases of basal cell carcinoma, and two cases of gastric adenocarcinoma, is described. The proband, who had three different primary tumors, died of gastric cancer, as did his father. Four of the proband's six siblings were affected with melanoma or basal cell cancer, as were two of his three children. Both daughters of one melanoma patient developed basal cell cancers. No spouses were affected, the cases were widely separated in time and place, and no unusual exposures were reported. HLA analysis of affected and unaffected first-degree relatives showed no association with antigens previously described in familial melanoma or segregation with a specific HLA haplotype. Although there was no association with HLA phenotype, these results suggest that melanoma, basal cell carcinoma, and gastric adenocarcinoma can be inherited in an autosomally dominant pattern similar to other familial tumor syndromes.

Premature sebaceous gland hyperplasia: successful treatment with isotretinoin

Hyperplasia of sebaceous glands is a common cause of papulonodular facial lesions that occur in middle-aged and older patients. Recently, several cases of premature sebaceous gland hyperplasia have been reported. In these patients the lesions had persisted despite vigorous attempts at therapy. We present a case of premature sebaceous gland hyperplasia that was successfully treated with isotretinoin.