A Free, Open-Source Toolkit to Produce 3D Bolus in the Clinic

PURPOSE/OBJECTIVE(S)

Tissue-equivalent, tissue-approximating and tissue-replacing bolus materials have been in use for decades in radiotherapy. Most frequently these materials are applied to a patient's skin to bring the highest dose region towards the surface of the skin-which is the location of the target. These materials can be applied at the time of simulation and included in a planning CT scan, or can be added during the planning process and first physically applied at the time of treatment. One of the most widely adopted materials for bolus has been sheets of a commercially available proprietary synthetic gel, which is uniform in thickness, and has some ability to match the curvature of the patient's body. Recently investigators have worked to create boluses using 3D printing technology, including several commercially available offerings. We hypothesized that we could create a bespoke, 3D bolus solution, using a series of open-source and free software products.

MATERIALS/METHODS

For an anthropomorphic phantom, a radiation treatment plan representative of skin cancer treatment was designed, this included a superficial target. The DICOM CT and structure set were imported into 3D Slicer, which is a free, open-source software for visualization, processing, segmentation, and registration. Using 3D Slicer, the bolus structure was saved as an STL file. Meshmixer, a free software for working with triangle meshes, was used to complete a mold design, and the mold parts were then printed using a rigid filament on a 3D printer. The mold parts were glued together, and small spring clamps were used secure the walls to the shells to ensure mold integrity. The mold was then filled with a thinned and degassed silicone. After appropriate curing, demolding was completed by removing the clamps and separating the walls. After QA, the bolus was applied to the anthropomorphic phantom and CTs were taken to compare a commercial sheet bolus with the in-house 3D printed product.

RESULTS

The bolus made via the in-house 3D printing process fit even complicated patient geometries well, and had both an obvious visual/goodness of fit advantage over the commercial sheet bolus and a nuanced dosimetric improvement as the air gaps present in the commercial sheet bolus were not desirable nor reproducible. The overall in-house workflow was efficient, and clinically reasonable (an estimated time of 72 hours was presented to the physician team, but in testing less than 24 hours was needed from export to delivery of the finished product).

CONCLUSION

In this work we explored whether motivated groups and departments could produce dosimetrically accurate and clinically reasonable custom boluses for patients undergoing radiotherapy to a superficial area of the body, using a test case on an anthropomorphic phantom. We found that this was absolutely achievable and could be implemented with no funds spent on software or licenses. Provided that a 3D printer, filament and silicone are available, any thoughtful practice can join the bespoke-bolus-club.

Real-time assessment of resource utilization and subsequent cost analysis in cancer patients (pts) near the end of life (EOL)

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Background: Aggressive medical interventions and associated high costs of care for cancer pts near the EOL are common. Addressing this issue at the local level requires an accurate, automated process to merge real-time clinical EHR data with cost data for performance reporting. Methods: This was a single-center, observational cohort study of decedents treated with anticancer therapy (antiCT) in the last 6 months of life from January 2016 to October 2017. Pts were stratified by antiCT use in the last 30 days of life. The primary outcome measure was total cost of care. Secondary outcome measures (hospitalizations, ER and ICU utilization, antiCT use, and hospice referral) were obtained through Flatiron Health EHR-based automated data processing. Cost data were merged from the Value-Driven Outcomes analytics framework. Results: 650 pts were included. 228 (35.1%) received antiCT in the 30 days before death. Non-drug costs for pts who received antiCT in the last 30 days of life were higher than those who did not (p < 0.01, median 38X higher). A higher proportion of pts who received antiCT in the last 30 days of life had ≥1 ER visit (29.4% vs 9.5%, p < 0.01) and hospital admission (58.8% vs 27.3%, p < 0.01) during the last 30 days. In addition, more of these pts received ICU care (35.5% vs 11.4%, p < 0.01). AntiCT in the last 30 days was associated with shorter median time from first hospice referral to death (1.4 vs 4.7 weeks; IQR 0.7-2.0 vs 3.14-7.7 weeks, p < 0.01). Distribution of antiCT types administered to pts in the last 30 days versus those given antiCT > 30 days from the EOL was significantly different, with the most substantial difference seen in the proportion of pts receiving immunotherapy (20.2% vs 12.6%, p = 0.04). Conclusions: Real-time assessment of EOL outcomes shows antiCT in the last 30 days of life is associated with aggressive medical interventions and increased total cost of care. Future research should identify pts who are unlikely to benefit from aggressive care, and whether performance reporting to oncologists will reduce futile interventions near the EOL.

The value of urgent care dermatology

OBJECTIVE

To determine whether urgent care dermatology adds value (service + quality/cost) to healthcare.

METHODS

A retrospective cross-sectional chart review of dermatologic patients in three service settings was compared: an urgent care dermatology clinic (same day dermatology [SDD]), the emergency department (ED), and a general dermatology clinic. Study period was July 1-September 30, 2014, for ED and SDD patients and August 2014 for general dermatology patients. ED patients had diagnoses of dermatitis (629.9) or rash (782). Final diagnoses, visit length, and no-show rates were determined. Cost and charge data for patients seen in SDD versus the ED were provided by the university, without raw data available for publication.

RESULTS

For matched diagnoses, ED visits were 105 (95% CI: 68.7-152.4, P < 0.001) minutes longer than SDD visits. Compared to SDD, no-shows in the general dermatology clinic were 2.24 times more likely (95% CI: 1.0003-5.02, P = 0.045). The odds for an SDD patient to be diagnosed with a code that was also seen in the ED was 13.0 (95% CI: 8.0-21.2, P < 0.01) times higher than the odds for the same diagnosis to be given to patients seen in the general dermatology clinic. ED visits cost 25% more than SDD visits. Patient charges for an ED visit are 207% more than for an SDD visit.

CONCLUSIONS

Urgent care dermatology clinic adds value to the healthcare system by providing quality care and excellent service at low cost. Dermatologists better utilize their skills by seeing acute, often-serious patients who would have otherwise been seen in the ED.

Infection-related mortality in Hispanic and non-Hispanic children with cancer

BACKGROUND

Hispanic children with cancer experience poorer survival than their White counterparts. Infection is a known cause of cancer-related mortality; however, little is known about the risk of infection-related death among Hispanic children with cancer. We examine the association of Hispanic ethnicity with infection-related mortality and life-threatening events among children with cancer.

PROCEDURE

For a cohort of all pediatric cancer patients diagnosed from 1986 to 2012 and treated at a single tertiary care center, we obtained national death records to determine all-cause mortality and infection-related mortality, as well as intensive care unit (ICU) admissions as a surrogate for life-threatening events. Cox proportional hazard models assessed all-cause mortality and infection-related mortality using ethnicity as the main independent variable. ICU admission rates were modeled using a zero-inflated Poisson regression model. Models were adjusted for gender, diagnosis year, age, residential location, and diagnosis.

RESULTS

Of 6,198 patients, 741 (12%) were Hispanic. Mean follow-up was 11 years (SD = 8.04). There were 1,205 deaths, with 193 attributable to infection. Differences in all-cause mortality between Hispanic and non-Hispanic patients did not reach significance (hazard ratio [HR] = 1.14, 95% confidence interval [CI]: 0.96-1.36). However, Hispanic patients were 68% (HR = 1.68, 95% CI: 1.16-2.43) more likely to have an infection-related cause of death. Hispanic ethnicity was statistically associated with a higher rate of ICU admissions (rate ratio = 1.32, 95% CI: 1.12-1.56).

CONCLUSION

Hispanic pediatric cancer patients were more likely to have an infection-related death and higher rates of ICU admissions than non-Hispanic patients. Infection may be an overlooked contributor to poorer outcomes among Hispanic patients.

A statewide quality improvement collaborative to reduce neonatal central line-associated blood stream infections

OBJECTIVE

The objective of this study was to reduce central line-associated blood stream infections (CLABSIs) among 13 collaborating regional neonatal intensive care units by 25%. We tested the hypothesis that change could be attributed to the quality improvement collaborative by testing for 'special cause' variation.

STUDY DESIGN

Our prevention project included five features: (1) leadership commitment, (2) potentially best practices, (3) collaborative processes, (4) audit and feedback tools and (5) quality improvement techniques. Baseline (1 January 2006 to 30 August 2006) data were compared with the intervention (1 September 2006 to 30 June 2007) and post-intervention (1 July 2007 to 30 December 2007) periods and analyzed using statistical process control (SPC) methods.

RESULT

We detected special cause variation, suggesting that the collaborative was associated with reduced infection rates, from 4.32 to 3.22 per 1000 line days (a 25% decrease) when comparing the baseline with the follow-up period.

CONCLUSION

The collaborative's process was associated with fewer infections. SPC suggested that systematic changes occurred. The remaining challenges include sustaining or even further reducing the infection rate.

Skeletal muscle acidosis correlates with the severity of blood volume loss during shock and resuscitation

BACKGROUND

Continuous assessment of tissue perfusion and oxygen utilization may allow for early recognition and correction of hemorrhagic shock. We hypothesized that continuously monitoring skeletal muscle (SM) PO2, PCO2, and pH during shock would provide an easily accessible method for assessing the severity of blood loss and the efficacy of resuscitation.

METHODS

Thirteen anesthetized pigs (25-35 kg) underwent laparotomy and femoral vessel cannulation. Multiparameter fiberoptic sensors were placed in the deltoid (SM) and femoral artery. Ventilation was maintained at a PaCO2 of 40-45 mm Hg. Total blood volume (TBV) was measured using an Evans blue dye technique. Animals were bled for 15 minutes, maintained at a mean arterial pressure (MAP) of 40 mm Hg for 1 hour, resuscitated (shed blood + 2 times shed volume in normal saline) and observed for 1 hour. Four animals served as controls (sham hemorrhage). Blood and tissue samples were taken at each time point.

RESULTS

Blood loss ranged from 28.5-56% of TBV. SM pH and SM PO2 levels fell rapidly with shock. SM PO2 returned to normal with resuscitation; however, SM pH did not return to baseline. SM PCO2 significantly rose with shock, but returned to baseline promptly with resuscitation. There was a significant correlation between SM pH and blood volume loss at end shock (r2 = 0.73, p < 0.001) and recovery (r2 = 0.84, p < 0.001). Animals (n = 2) whose SM pH did not recover to 7.2 were found to have ongoing blood loss from biopsy sites and persistent tissue hypercarbia despite normal MAP.

CONCLUSION

Continuous multiparameter monitoring of SM provides a minimally invasive method for assessing severity of shock and efficacy of resuscitation. Both PCO2 and PO2 levels change rapidly with shock and resuscitation. SM pH is directly proportional to lost blood volume. Persistent SM acidosis (pH < 7.2) and elevated PCO2 levels suggest incomplete resuscitation despite normalized hemodynamics.

By any other name: when will preschoolers produce several labels for a referent?

Two experiments investigated why preschool children sometimes produce multiple words for a referent (i.e. polynomy), but other times seem to allow only one word. In Experiment 1, 40 three- and four-year-olds completed a modification of Deák & Maratsos' (1998) naming task. Although social demands to produce multiple words were reduced, children produced, on average, more than two words per object. Number of words produced was predicted by receptive vocabulary. Lexical insight (i.e. knowing that a word refers to function or appearance) and metalexical beliefs (i.e. that a hypothetical referent has one label, or more than one) were not preconditions of polynomy. Polynomy was independent of bias to map novel words to unfamiliar referents. In Experiment 2, 40 three- and four-year-olds learned new words for nameable objects. Children showed a correction effect, yet produced more than two words per object. Children do not have a generalized one-word-per-object bias, even during word learning. Other explanations (e.g. contextual restriction of lexical access) are discussed.

Is a share buyback right for your company?

Contrary to popular wisdom, buybacks don't create value by raising earnings per share. But they do indeed create value, and in two very different ways. First, a buyback sends signals about the company's prospects to the market--hopefully, that prospects are so good that the best investment managers can make right now is in their own company. But investors won't see it that way if other, negative, signals are coming from the company, and it's rarely a good idea for companies in high-growth industries, where investors expect that money to be spent pursuing new opportunities. Second, when financed as a debt issue, a buyback is essentially an exchange of equity for debt, conferring the traditional benefits of leverage--a tax shield and a discipline for managers. For such a buyback to make sense, a company would need to have taxable profits in need of shielding, of course, and be able to predict its future cash flows fairly accurately. Justin Pettit has found that managers routinely underestimate how many shares they need to buy to send a credible signal to the markets, and he offers a way to calculate that number. He also goes through the iterative steps involved in working out how many shares must be purchased to reach a target level of debt. Then he takes a look at the advantages and disadvantages of the three most common ways that companies make the actual purchases--open-market purchases, fixed-price tender offers, and auction-based tender offers. When a company's performance is lagging, a share buyback can look attractive. Unfortunately, a buyback can backfire--unless executives understand why, when, and how to use this powerful and risky tool.

Bioelectrical impedance analysis in the evaluation of the nutritional status of continuous ambulatory peritoneal dialysis patients

The authors evaluated the nutritional status of 47 continuous ambulatory peritoneal dialysis (CAPD) patients, 26 men (age 58.9 +/- 14.6 years, duration on CAPD 27.3 +/- 18.3 months) and 21 women (age 56.2 +/- 14.9 years, duration on CAPD 34.5 +/- 23.4 months), using subjective global assessment (SGA), an established method for the nutritional assessment of dialysis patients, and bioelectrical impedance analysis (BIA: body cell mass, fat mass, and phase angle). Of the studied patients, 19 were diabetic (age 59.7 +/- 13.8 years, duration on CAPD 29.2 +/- 19.7 months) and 28 were non diabetic (age 53.9 +/- 14.3 years, duration on CAPD 31.5 +/- 21.8 months. According to SGA, 24 patients were scored as well nourished (Group I), 18 as mildly malnourished (Group II), and 5 as moderately malnourished (Group III). No patient scored as severely malnourished (Group IV). Analysis of the main nutritional parameters for the subgroups revealed a proportional decrease in phase angle, with a statistically significant correlation (p < 0.009) between phase angle and SGA. No significant difference was seen in serum albumin levels between patients in Group I and Group II, but the mean level was significantly lower in patients in Group III compared to Group I. The nutritional and biochemical data in diabetic patients and non diabetic patients were not significantly different. BIA phase angle seems to be a simple and reliable method for the routine assessment of nutritional status in CAPD patients.

Effects of amino acid dialysate on appetite in CAPD patients

The use of amino acid (AA) dialysate in CAPD patients may have theoretical disadvantages, since protein ingestion is known to suppress food intake in humans disproportionately to its energy value. Therefore we measured subjective appetite and food intake of CAPD patients in a cross-over study of 16 subjects (age 22-75 years, BMI 19-31, > 3 months on CAPD, non-diabetic and not protein malnourished). They received, in random order, either 4 weeks of dextrose only (their usual treatment), or one AA (1%) exchange replacing the first dextrose exchange each day. Subjective measurements of food intake (3 day food record) and quantitative measurements of lunch time food intake were obtained during a morning dextrose exchange after 28 days of each regimen. Except for a reduction in feelings of fullness during the AA treatment, there were no effects on feelings of hunger/satiety, food appeal, lunch-time food intake, or on 3-day food intake. We conclude that the use of a daily AA (1%) dialysate for 4 weeks does not affect subjective appetite or food intake of CAPD patients. There may even be a beneficial effect as the feeling of fullness decreased with the AA treatment.

Use of lymphoscintigraphy in chyluria

The roentgenographic procedure of choice in delineating lymphatic channels has been lymphangiography. Recently, radionuclide lymphoscintigraphy has been used to outline lymphatics in patients with various lymphatic disorders. We present and compare the results of lymphangiography and lymphoscintigraphy in 2 patients with chyluria. Since the results of lymphoscintigraphy correlated with lymphangiography, the application of this less invasive technique in the diagnosis and management of chyluria may be warranted.

Reconstruction of penile agenesis by a posterior sagittal approach

Penile agenesis is a rare condition requiring gender reassignment and staged perineal reconstruction. This report describes two children reconstructed by taking advantage of the posterior sagittal approach. This approach allows a precise anatomic dissection, construction of a neovagina and accurate positioning of all perineal orifices. We think that this is the preferred approach for this rare condition.

Isolation and experimental chicken-embryo-inoculation studies with budgerigar papovavirus

Attempts to isolate and identify budgerigar papovavirus (BPV) were made during three separate outbreaks of disease diagnosed on pathological grounds. Direct electron microscopy was successful only when large areas of skin were extensively disrupted to release virus and then extracted with fluorocarbon to remove lipids. Direct inoculation of budgerigar tissue suspensions into chicken embryos or chicken cell cultures failed to produce detectable virus. However, when primary cultures of liver and kidney were prepared from affected budgerigars, BPV could be detected by electron microscopy and by the production of a cytopathic effect at the third or fourth passage in cell cultures. The isolated virus was pathogenic for 10-day-old but not 11- or 12-day-old chicken embryos. Inoculated 11- and 12-day-old embryos produced antibodies to BPV that were detectable 2 weeks after hatching by agar-gel-immunodiffusion tests.