Technical note: Determination of proton linear energy transfer from the integral depth dose

BACKGROUND

Proton linear energy transfer (LET) is associated with the relative biological effectiveness of radiation on tissues. Monte Carlo (MC) simulations have been known to be the preferred method to calculate LET. Detectors have also been built to measure LET, but they need to be calibrated with MC simulations.

PURPOSE

To propose and test a MC-free method for determining LET from the measured integral depth dose (LFI) of the protons of interest.

METHOD AND MATERIALS

LFI consists of three steps: (1) IDD measurements, (2) extraction of energy spectrum (ES) from the IDD, and (3) LET determination from the extracted ES and the stopping power of each energy. To validate the accuracy of the extraction of ES, we use Gaussian ES to synthesize IDD, extract ES from the synthesized IDD, and then compare the original (ground truth) and extracted ES. LETs calculated from the original and extracted ES are also compared. To obtain the LET of protons of interest, we measure IDDs by a large-area plane-parallel ionization chamber in water. Finally, TOPAS MC is employed to simulate IDDs, ES, and LETs. From the simulated IDD, the extracted ES and LET are compared with the simulations from TOPAS MC.

RESULTS

From the synthesized IDDs, the LETs agreed excellently when the peak energies ≥10 and 1.25 MeV with depth resolutions 0.1 and 0.01 mm, respectively. For energy <1.25 MeV, even higher depth resolution than 0.01 mm is required. From the MC simulated IDDs, our track-averaged LET excellently agreed with MC simulation, but not the LETd . Our LETd was smaller than MC simulated LETd in the shallow region but larger in the distal Bragg peak region.

CONCLUSION

LET can be accurately determined from the IDD. This method can be used in the clinic to commission or validate LETs from other measurement methods or a treatment planning system.

[Efficacy analysis of surgical combined with postoperative adjuvant therapy for T3 gallbladder carcinoma: a multicenter retrospective study]

Objective: To explore the clinical value of adjuvant therapy in patients with T3 gallbladder cancer (GBC) who have undergone R0 resection. Methods: Clinical and pathological data from 415 patients with T3 GBC who underwent surgical treatment in 7 tertiary centers in China from January 2013 to December 2018 were collected,including 251 males and 164 females,aged (61±11)years (range: 26 to 88 years). Depending on whether to receive adjuvant therapy after radical resection,the patients were divided into the radical resection group alone (group A,n=358) and the radical resection combined with the postoperative adjuvant therapy group (group B,n=57). The general data of the two groups were matched 1∶1 by propensity score matching method,and the caliper value was 0.02.Clinicopathological characteristics,overall survival and disease-free survival of the two groups were compared.The Cox regression model was used for multivariate analysis,and patients with at least one or more independent risk factors were classified as high-risk clinicopathological subtypes. Subgroup analysis was performed to assess the clinical value of adjuvant therapy after radical resection in patients with high-risk clinicopathological subtypes. Results: After the matching,there were 42 patients in each of the two groups. The incidence of gallbladder cancer and the number of dissected lymph nodes in group B after cholecystectomy were higher than those in group A (χ2=9.224,2.570,both P<0.05). There were no significant differences in overall survival rate and disease-free survival rate between the two groups before and after matching (all P>0.05). The results of the univariate and multivariate analysis showed that CA19-9>39 U/ml,nerve invasion,tumor location (liver side or bilateral),TNM stage ⅢB to ⅣB ,poorly differentiated tumor were independent prognostic factors of overall survival and disease-free survival of patients with T3 stage gallbladder cancer (all P<0.05).Three hundred and twenty-nine patients(79.3%) had high-risk clinicopathological subtypes,and the median survival time after curative resection with and without adjuvant therapy was 17 months and 34 months respectively,and the 3-year and 5-year overall survival rates were respectively 40.0%,21.3% and 46.0%,46.0% (χ2=4.042,P=0.044);the median disease-free survival time was 9 months and 13 months,and the 3-year and 5-year disease-free survival rates were 23.4%,13.6% and 30.2%,18.2% (χ2=0.992,P=0.319). Conclusions: Postoperative adjuvant therapy following radical surgery did not yield significant improvements in the overall survival and disease-free survival rates of patients diagnosed with T3 gallbladder cancer. However, it demonstrated a significant extension in the overall survival rate for patients presenting high-risk clinicopathological subtypes.

[Epidemiological characteristics of reinfection of 2019-nCoV and influencing factors in Ningbo]

Objective: To analyze the epidemiological characteristics of reinfection of 2019-nCoV and influencing factors, and provide evidence for effective prevention and control of COVID-19 epidemic. Methods: The incidence data of COVID-19 in Ningbo from January 1, 2020 to November 30, 2022 were collected from the infectious disease surveillance system of Chinese information system for disease control and prevention. The incidence of reinfection of 2019-nCoV was investigated by using questionnaire. logistic regression analysis was used to analyze the influences of gender, age, time interval from the first infection, history of underlying disease, 2019-nCoV vaccination dose and disease severity on the reinfection. Results: A total of 897 previous 2019-nCoV infection cases were investigated, of which 115 experienced the reinfection of 2019-nCoV, the reinfection rate was 12.82%. The interval between the two infections M(Q1, Q3) was 1 052 (504, 1 056) days. Univariate analysis showed that age, 2019-nCoV vaccination dose, history of underlying disease, type of 2019-nCoV variant causing the first infection, time interval from the first infection and severity of the first infection were associated with the reinfection rate (all P<0.05). Multivariate logistic regression analysis showed that the risk for reinfection in age group 30- years was higher than that in age group ≥60 years (OR=2.10, 95%CI: 1.11-3.97). No reinfection occurred in those with time interval from the first infection of <6 months, and the risk for reinfection was higher in those with the time interval of ≥12 months than in those with the time interval of 6- months (OR=6.68, 95%CI: 3.46-12.90). The risk for reinfection was higher in the common or mild cases than in the asymptomatic cases (OR=2.64, 95%CI: 1.18-5.88; OR=2.79, 95%CI: 1.27-6.11). Conclusion: The time interval from the first infection was an important influencing factor for the reinfection of 2019-nCoV, and the probability of the reinfection within 6 months was low.

[Application of high-density polyethylene implants in adult cleft lip and palate nasal deformity and dysfunction]

Objective: Through the use of high-density polyethylene implants in adults with cleft lip and palate nasal deformities and abnormal functions, to evaluate the clinical effect of postoperative patients on improving nasal shape and symptoms. Methods: A retrospective study of 12 patients with nasal deformities after cleft lip and palate surgery in the Shanghai Ninth People's Hospital Affiliated to Shanghai JiaoTong University School of Medicine from January 2018 to January 2022 was completed, including 7 males and 5 females, with the age ranging from 18 to 29 years. All the patients underwent nasal deformity correction, and nasal septum correction was performed if necessary. High-density polyethylene implants (MEDPOR/Su-Por) were used intraoperatively. Follow-up for at least 6 months was performed to measure the relevant appearance indicators and subjective Visual Analog Scale (VAS) scores, and to compare the clinical effects before and after surgery. SPSS 22.0 software was used for statistical analysis. Results: Before and after surgery, the average VAS score of nasal obstruction decreased by (4.83±0.94) points; the average VAS score of appearance satisfaction increased by (3.92±1.08) points; the height of nasal columella was increased by (1.79±0.78)mm; the height of nasal tip was increased by (2.79±1.50)mm; the height of ipsilateral nostril was increased by (1.83±0.62)mm; the width of the ipsilateral nasal floor was reduced by (0.42±0.47)mm. All of above were statistically significant (all P<0.05). Conclusion: High-density polyethylene implants can effectively improve the shape and function of the nose in operations related to cleft lip and palate nasal deformity and abnormal functions, and are an ideal synthetic material.

[A nested case-control study on the association of neonatal cord blood selenium, iron and copper with congenital heart disease]

Objective: To investigate the relationship between the levels of selenium, iron and copper in cord blood of neonates and the risk of congenital heart disease (CHD), and analyze their interaction effects. Methods: The subjects were obtained from the birth cohort in Lanzhou area established from 2010 to 2012. A baseline survey was conducted in the first trimester, and the follow-up was conducted in the second trimester, third trimester and 42 days after delivery. The umbilical vein blood was collected from newborns at delivery, and information on their birth outcomes was extracted from medical records. A nested case-control study was used to select 97 neonates with CHD newly diagnosed by echocardiography as the case group, and 194 neonates were selected as the control group by 1∶2 matching according to their mother's age, block and CHD onset time. Inductively coupled ion mass spectrometry was used to detect the concentrations of selenium, iron and copper in neonatal cord blood. The element exposure was categorized into three groups, the low, medium and high concentrations, according to the quartiles Q₁ and Q₃ of selenium, iron and copper concentrations in the control group. The association between cord blood selenium, iron and copper concentrations and CHD was analyzed by conditional logistic regression model using medium concentration as the reference standard. The association of their interactions with CHD was analyzed by a phase multiplication model. Results: The M (Q₁, Q₃) concentration of neonatal cord blood copper was 746.12 (467.48, 759.74) μg/L in the case group and 535.69 (425.21, 587.79) μg/L in the control group, with a statistically significant difference between the two groups (P<0.05). After adjustment for confounders, logistic regression models showed that the risk of CHD development was increased in neonates with either high copper in cord blood (OR=4.062, 95%CI: 2.013-8.199) or high copper combined with high iron (OR=3.226, 95%CI: 1.343-7.750). No correlation was observed between selenium and iron concentrations and the development of CHD in neonates. There was a multiplicative interaction between copper and iron in cord blood on the risk of developing CHD (OR=1.303, 95%CI: 1.056-1.608). Conclusion: There is a multiplicative interaction between iron and copper elements. The high copper and the high copper combined with high iron in umbilical cord blood are risk factors for neonatal CHD.

Use of CBCT plus plan robustness for reducing QACT frequency in intensity-modulated proton therapy: Head-and-neck cases

PURPOSE

Anatomic variation has a significant dosimetric impact in intensity-modulated proton therapy. Weekly or biweekly computed tomography (CT) scans, called quality assurance CTs (QACTs), are used to monitor anatomic and resultant dose changes to determine whether adaptive plans are needed. Frequent CT scans result in unwanted QACT dose and increased clinical workloads. This study proposed utilizing patient setup cone-beam CTs (CBCTs) and treatment plan robustness to reduce the frequency of QACTs.

METHODS

We retrospectively analyzed data from 27 patients with head-and-neck cancer, including 594 CBCTs, 136 QACTs, and 19 adaptive plans. For each CBCT, water-equivalent thickness (WET) along the pencil-beam path was calculated. For each treatment plan, the WET of the first-day CBCT was used as the reference, and the mean WET changes (ΔWET) in each following CBCT was used as the surrogate of proton range change. Using CBCTs acquired prior to a QACT, we predicted the ΔWET on the QACT day by a linear regression model. The impact of range change on target dose was calculated as the predicted ΔWET weighted by the monitor units of each field. In addition, plan robustness was estimated from the robust dose-volume histograms (DVHs) and combined with ΔWET to reduce QACT frequency. Robustness was estimated from the distance between the DVH curves of the nominal and worst scenarios.

RESULTS

When the estimated mean ΔWET was <6.5 mm (or <7.5 mm if the robustness was >95%), the QACT could be skipped without missing any adaptive planning; otherwise a QACT was required. Overall, 41% of QACTs could be eliminated when ΔWET was <6.5 mm and 56% when ΔWET was <7.5 mm, and robustness was >95%. At least one QACT could have been omitted in 25 of the 27 cases under skipping thresholds at ΔWETs <7.5 mm and R > 95%.

CONCLUSION

This study suggests that the number of QACTs can be greatly reduced by calculating range change in patient setup CBCTs and can be further reduced by combining this information with analyses of plan robustness.

[Epidemiological characteristics of a local cluster epidemic caused by 2019-nCoV Delta variant in Ningbo, 2021]

Objective: To understand the epidemiological characteristics of a local clustered epidemic caused by 2019-nCoV Delta variant in Ningbo and provide reference for the improvement of COVID-19 epidemic prevention and control. Methods: Case finding was conducted based on case definitions, and field epidemiological investigation of COVID-19 cases was carried out. In which Nasal and oropharyngeal swabs of the cases were collected for pathogen testing, and the results were analyzed with descriptive epidemiological methods. Results: A total of 74 COVID-19 cases were reported in this epidemic, and the cases were mainly mild ones, accounting for 87.84% (65/74), and there were no severe or critical cases. The epidemic curve showed a human-to-human transmission mode, indicating that a transmission for at least six generations had occurred. The age of the COVID-19 patients ranged from 2 years to 80 years, and 27.03% (20/74) of the cases were older than 60 years. The cases were mainly workers (55.41%, 41/74) and housework/the unemployed (27.03%, 20/74). The COVID-19 epidemic was limited, and no further spread to other areas occurred. The transmission chain among the cases was clear, and the gene sequencing results confirmed that the current epidemic was caused by 2019-nCoV Delta variant, which was highly homologous to the strains from other province. Conclusion: The local COVID-19 epidemic in Ningbo was caused by imported cases of COVID-19 from other province, and local community spread occurred through daily contacts between cases and contacts.

[Analysis on infection risk in secondary close contacts of COVID-19 patients]

Objective: To study the infection rate of secondary close contacts of COVID-19 patients, and assess the infection risk in the contacts. Methods: COVID-19 patients' close contacts (with a clear exposure time to index case) with negative nucleic acid test results and secondary close contacts were surveyed in continuous isolation and medical observation in this prospective study. The dynamic nucleic acid test results of the close contacts and secondary contacts of COVID-19 patients were collected to assess their risk of infection. Results: A total of 4 533 close contacts were surveyed, in whom 14 were confirmed as COVID-19 patients with overall secondary attack rate of 0.31%, and 4 201 secondary contacts were tracked, in whom no subsequent infections occurred. Conclusion: Close contacts of COVID-19 patients entered in centralized isolation for medical observation with negative nucleic acid tese results,the secondary close contacts of COVID-19 patients have no risk of infection.

[Transmission chains of local epidemic of COVID-19 caused by 2019-nCoV Delta variant in Zhenhai district, Ningbo]

Objective: To investigate the local epidemic of COVID-19 caused by 2019-nCoV Delta variant in Zhenhai district of Ningbo, identify the transmission chain and provide reference for the prevention and control of COVID-19 epidemic. Methods: The incidence data of COVID-19 in Zhenhai from 6 to 18 December, 2021 were collected in field investigation. Field epidemiological investigation was conducted to understand the epidemiological characteristics of COVID-19 cases and analyze the transmission chains. Results: The first case might be infected with 2019-nCoV through direct or indirect exposure when passing through a medium-risk area, then a family cluster was caused, and the epidemic spread through close contacts of family members with others such as work, daily life, and moxibustion. The epidemic lasted for 14 days, and 74 confirmed COVID-19 cases were reported. The median incubation period was 4.0(3.0,5.8)d. All the cases were in a chain of transmission for more than 6 generations, and the intergenerational interval was 3.5(2.0,5.3)d. The gene sequencing result indicated that the pathogen was Delta AY.4 variant of 2019-nCoV. Both the epidemiological investigation and the gene sequencing results supported that the local COVID-19 epidemic in Zhenhai was associated with the COVID-19 epidemic in Shanghai. Conclusions: The transmission chain of this epidemic was clear. Delta AY.4 variant has obvious characteristic to cause case clusters in families, places with poor ventilation, and residential communities. It is suggested to strengthen the health management in key areas and key populations, and increase the frequency of nucleic acid testing.

[Analysis on infectivity of COVID-19 patients before and after last negative nucleic acid test]

Objective: To investigate the infection rate in close contacts of COVID-19 patients before and after the last negative nucleic acid test, evaluate the effect of dynamic nucleic acid test in determining the infectivity of COVID-19 patients. Methods: Dynamic nucleic acid test results of COVID-19 cases were collected in a retrospective cohort study. COVID-19 cases with negative nucleic acid test results before their first positive nucleic acid tests were selected as study subjects. Close contacts of the index cases and the secondary close contacts were kept isolation for medical observation to assess their risk of infection. Results: This study included 89 confirmed cases from two local COVID-19 epidemics in Ningbo. A total of 5 609 close contacts were surveyed, the overall infection rate was 0.20%. No close contacts of the COVID-19 cases before the last negative nucleic acid test were infected, and the infection rate in the close contacts of the COVID-19 cases after the last negative nucleic acid test was 1.33%, all of these close contacts lived together with the index cases. No secondary close contacts were infected. Conclusion: COVID-19 patient becomes infectious after the last nucleic acid is negative, and has no infectivity before the last nucleic acid negative.

[Fracture images in temple murals for sacrificial activities in the Ming and Qing Dynasties in Shanxi]

A great number of 'fracture images' in murals remain in some temples in Shanxi province, describing Buddhist rituals for sacrificial activities in the Ming and Qing Dynasties. Some 'fracture images', such as 'splint fixation method' and 'suspension fixation method', were found in Puguang Temple, Yunlin Temple and Yong'an Temple. These murals with 'fracture images' demonstrated characteristics of secularisation and realistic style, as vivid portrayals of surgical medicine in the Ming Dynasty. For instance, one of the pictures in Puguang Temple clearly described the shape of orthopedic splints at that time. The depictions in 'fracture images' in temple murals were basically consistent with the records in ancient literature based on the investigation on fracture treatment in the history of traditional Chinese medicine. They provided visual materials for further study of orthopedic history.

[Effectiveness of precise prevention and control strategies of dynamic zero COVID-19 in Ningbo, Zhejiang province]

Objective: To evaluate effectiveness of the precise prevention and control strategies of dynamic zero COVID-19 in Ningbo, Zhejiang province. Methods: Based on the incidence data of COVID-19 and case epidemiological survey report in Ningbo in December 2021, the incidence curve of COVID-19 was generated and a dynamics model was developed to estimate the case number of under different intervention measures. The basic reproduction number (R₀) and real-time reproduction number (R_t) were calculated to evaluate intervention effect. Results: A total of 74 cases of COVID-19 had been confirmed in Ningbo as of 17 December, 2021. The R₀ was estimated to be 4.3. With the strengthening of prevention and control measures, the R_t showed a gradual downward trend, dropping to below 1.0 on December 11 and 0.4 on December 14. The model fitting results showed that the actual case number was close to the estimated case number (76 cases) when the effectiveness of intervention was 90%. The number of cases decreased by 98.4% compared with that if no intervention was taken. Conclusion: The precise prevention and control strategies of dynamic zero COVID-19 have obvious effect, which can facilitate the rapid control of COVID-19 epidemic in Ningbo.

Impact of nodular calcification on the outcomes of patients with acute coronary syndrome (ACS) treated with primary percutaneous coronary intervention (PCI)

Background

Calcified plaque is thought to adversely impact clinical outcomes but the impact of nodular calcification after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS) remains unclear.

Purpose

This study sought to explore the impact of nodular calcification on the outcomes of patients undergoing percutaneous coronary intervention for acute coronary syndromes.

Methods

Five-hundred culprit plaque with calcification were analysed from 495 ACS patients in whom PCI was performed. Plaques were divided into nodular calcification group (n=238) and non-nodular calcification group (n=262). Calcification is defined as an area with low back-scattering signal and a sharp border. Nodular calcification was defined as a protruding mass with an irregular surface, high backscattering, and signal attenuation on optical coherence tomography (OCT).

Results

Patients with nodular calcification were older (p&lt;0.001) and had lower left ventricular ejection fraction (p=0.006) compared to patients with non-nodular calcification. Lesion length (31 (25.2, 38.5) vs. 29 (22.8, 34.1), p&lt;0.001) was longer in plaques with nodular calcification. A higher prevalence of superficial calcium (p&lt;0.001) was observed in plaques with nodular calcification compared with non-nodular calcification group. Minimum stent area (MSA) (5.0 (3.9, 6.3) vs. 5.4 (4.2, 6.7), p=0.011) and stent expansion (70 (62.7, 81.8) vs. 75 (65.2, 86.6), p=0.004) were significantly smaller in the nodular calcification group than in the non-nodular calcification group. Independent predictors of nodular calcification were age (p&lt;0.001) lesion length (p=0.002) and calcium depth (p&lt;0.001).

Conclusion

This study demonstrated that the presence of nodular calcification is associated with unfavourable outcomes with smaller minimum stent area and higher incidence of stent under expansion in patients with ACS treated with primary PCI.

Funding Acknowledgement

Type of funding sources: None.

Frequency and predictors of thin-cap fibroatheroma progression: a comprehensive and dynamic in-vivo OCT study

Purpose

To assess the evolution of thin-cap fibroatheroma (TCFA) and to explore predictors for its progression by using optical coherence tomography (OCT) in patients with acute coronary syndrome (ACS).

Methods

We enrolled ACS patients with non-culprit TCFA at baseline and corresponding OCT images at follow-up of 9 to 15 months. Clinical, angiographic and OCT data were collected and analyzed according to established methods. TCFA was defined as a lipid plaque with maximum lipid arc &gt;90° and fibrous cap thickness &lt;65μm. Considering the resolution of OCT, the regression of TCFA was defined as an increase of fibrous cap thickness &gt;10μm. Inversely, TCFA progression was defined as a decrease, constant or ≤10μm increase of fibrous cap thickness.

Results

41 patients with 55 non-culprit TCFAs were taken into final analysis. 17 patients (41.5%) had patient-level progression and 22 TCFAs (40.0%) progressed at plaque-level with a median follow-up duration of 371 days. 11 (20.0%) of the 55 TCFAs happened subclinical rupture at follow-up, including 10 with the formation a new layer and 1 without the detection of the new layer. Besides, another patient suffered re-myocardial infarction because of the rupture of TCFA induced acute thrombosis and lumen occlusion during follow-up. The baseline clinical and angiographic characteristics were similar between the two cohorts. The progression group had a significantly higher prevalence of macrophage infiltration and vasa vasorum at baseline than the non-progression group (Figure 1). Multivariate analysis identified macrophage infiltration (odds ratio [OR]: 5.30; 95% confidence interval [CI]: 1.01 to 27.91; p=0.049]) as the independent predictor of TCFA progression. When it came to the evolution of lesion morphology and lipid components, the progression cohort had a higher percent change of lumen stenosis and lipid length (Figure 2).

Conclusions

About 40% of non-culprit TCFAs in ACS patients progressed in fibrous cap thickness at a median interval of 1 year. Macrophage infiltration was the independent predictor of non-culprit TCFA progression. The progression of fibrous cap thickness was usually accompanied with an aggressive evolution of other lesion characteristics.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): the National Key R&D Program of China Baseline OCT characteristicsPercent change of lesion morphology

Gender-specific difference of clinical and plaque characteristics in myocardial infarction with non-obstructive artery (MINOCA): insights from optical coherence tomography

Background

To date, sparse data are available with regard to gender differences in coronary plaque morphology and composition as underlying mechanism of MINOCA.

Purpose

To assess the differences in coronary plaque morphology in culprit lesion between women and men with MINOCA using intravascular optical coherence tomography.

Methods

Totally, 7404 consecutives acute myocardial infarction patients who underwent emergency coronary angiography between 2016 and 2019 were screened. MINOCA were identified in 292 patients (mean age: 72.6% male, 54.1% with ST-segment elevation). Optical coherence tomography was performed in 190 patients (men, n=142).

Results

Women with MINOCA were older (62.5±10.6 vs. 54.0±11.5, P&lt;0.001) and more over 55 years (75.3% vs. 43.6%, P&lt;0.001). Although women with MINOCA more frequently presented with NSTEMI (56.8% vs. 41.7%, P=0.025) and prior coronary artery disease (CAD) (33.3% vs. 6.3%, P&lt;0.001), they were less likely smoker (27.2% vs. 58.8%, P&lt;0.001). There was no significant difference in incidence of plaque rupture, erosion and calcified nodule between men and women. However, women were more likely to have thin-cap fibroatheroma (TCFA) (39.6% vs. 22.5%, P=0.025).

Conclusion

Women with MINOCA were older, more frequently presented with NSTEMI and less smoking compared to men. Besides, more TCFA were observed in women.

Funding Acknowledgement

Type of funding sources: None. Clinical and OCT plaque profilesProportion of clinical and OCT profiles

In Situ Oxygen Generation Enhances the SCAP Survival in Hydrogel Constructs

Prolonged and severe hypoxia is the main cause of death of transplanted cells prior to the establishment of functional circulation. In situ generation of oxygen by oxygen-producing scaffolds-a unique solution that could produce and deliver oxygen to the adjacent cells independently of blood perfusion-has attracted considerable attention to enhance the survivability of the transplanted cells. However, the application of oxygen-generating scaffolds for facilitating cell survival in pulp-like tissue regeneration is yet to be explored. In this study, gelatin methacryloyl (GelMA)-a biocompatible scaffolding material that closely mimics the native extracellular matrix and is conducive to cell proliferation and differentiation-was used to fabricate oxygen-generating scaffolds by loading various concentrations of CaO₂. The CaO₂ distribution, topography, swelling, and pore size of CaO₂-GelMA hydrogels were characterized in detail. The release of O₂ by the scaffold and the viability, spreading, and proliferation of stem cells from apical papilla (SCAPs) encapsulated in the GelMA hydrogels with various concentrations of CaO₂ under hypoxia were evaluated. In addition, cellular constructs were engineered into root canals, and cell viability within the apical, middle, and coronal portions was assessed. Our findings showed that 0.5% CaO₂-GelMA was sufficient to supply in situ oxygen for maintaining the embedded SCAP viability for 1 wk. Furthermore, the 0.5% CaO₂-GelMA hydrogels improved the survivability of SCAPs within the coronal portion of the engineered cellular constructs within the root canals. This work demonstrated that 0.5% CaO₂-GelMA hydrogels offer a potential promising scaffold that enhances survival of the embedded SCAPs in endodontic regeneration.

[Evaluation of the effects auricular reconstruction with Medpor combined with hearing rehabilitation]

Objective: To investigate the clinical effects of single-stage auricular reconstruction and hearing rehabilitation in children with microtia and external auditory canal atresia. Methods: Sixty eight cases of microtia with external auditory canal atresia (53 males and 15 females, age from 7 to 12 years, with a median age of 8.8 years), who received operations in Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine from July 2017 to December 2019 were collected.A total of 28 cases received auricle reconstruction with high-density polyethylene (Medpor) framework and hearing reconstructions, among which 20 patients received the traditional external auditory canal and middle ear repair (EACR), and eight patients were implanted bone conduction device bone bridge(BB) simultaneously.In the control group, 40 patients only received Medpor frame implantation for auricle plasty. Postoperative changes in auricle morphology and auditory function and postoperative complications were evaluated. Results: After three to thirty months follow-ups, the auricles shape recovered well in all three groups. The average scores of 14 fine structures in the auricles were 9.43(EACR) and 10.67(BB) points. The average score of auricle symmetry were 6.83(EACR) and 6.00(BB) points. There was no significant difference compared to the auricle reconstruction group (8.23/6.20 points). P>0.05. After surgery, the average hearing improvement in the BB group was 43.33 dB HL and the average speech recognition threshold declined 42.28 dB HL. In the EACR group, the average hearing improvement was 4.13 dB HL and the average speech recognition threshold declined 11.36 dB HL. No vertigo, tinnitus, cerebrospinal fluid leakage and other complications occurred in all the patients. In the EACR group, sensorial hearing loss, auricle stent fracture, ear canal restenosis and ear canal atresia occurred in one patient respectively. In the auricle group, one auricle stent exposure and one facial branch nerve injury occurred. Nearly ten patients had difficulty in hair growth at scalp incisions. Conclusions: The operation of single-stage auricular reconstruction and hearing rehabilitation for microtia is feasible. The methods of hearing reconstruction should be determined by evaluating the development of the inner and middle ear of the patients. For those with poor mastoid development, bone bridge implantation is recommended to achieve a stable and significant hearing effect.

Toward automation of initial chart check for photon/electron EBRT: the clinical implementation of new AAPM task group reports and automation techniques

Purpose

The recently published AAPM TG‐275 and the public review version of TG‐315 list new recommendations for comprehensive and minimum physics initial chart checks, respectively. This article addresses the potential development and benefit of initial chart check automation when these recommendations are implemented for clinical photon/electron EBRT.

Methods

Eight board‐certified physicists with 2–20 years of clinical experience performed initial chart checks using checklists from TG‐275 and TG‐315. Manual check times were estimated for three types of plans (IMRT/VMAT, 3D, and 2D) and for prostate, whole pelvis, lung, breast, head and neck, and brain cancers. An expert development team of three physicists re‐evaluated the automation feasibility of TG‐275 checklist based on their experience of developing and implementing the in‐house and the commercial automation tools in our institution. Three levels of initial chart check automation were simulated: (1) Auto_UMMS_tool (which consists of in‐house program and commercially available software); (2) Auto_TG275 (with full and partial automation as indicated in TG‐275); and (3) Auto_UMMS_exp (with full and partial automation as determined by our experts’ re‐evaluation).

Results

With no automation of initial chart checks, the ranges of manual check times were 29–56 min (full TG‐315 list) and 102–163 min (full TG‐275 list), which varied significantly with physicists but varied little at different tumor sites. The 69 of 71 checks which were considered as “not fully automated” in TG‐275 were re‐evaluated with more automation feasibility. Compared to no automation, the higher levels of automation yielded a great reduction in both manual check times (by 44%–98%) and potentially residual detectable errors (by 15–85%).

Conclusion

The initial chart check automation greatly improves the practicality and efficiency of implementing the new TG recommendations. Revisiting the TG reports with new technology/practice updates may help develop and utilize more automation clinically.

Spatially Fractionated Radiotherapy (GRID) Prior to Standard Neoadjuvant Conventionally Fractionated Radiotherapy for Bulky, High-Risk Soft Tissue and Osteosarcomas: Feasibility, Safety, and Promising Pathologic Response Rates

Spatially fractionated radiotherapy (GRID) has been utilized primarily in the palliative and definitive treatment of bulky tumors. Delivered in the modern era primarily with megavoltage photon therapy, this technique offers the promise of safe dose escalation with potential immunogenic, bystander and microvasculature effects that can augment a conventionally fractionated course of radiotherapy. At the University of Maryland, an institutional standard has arisen to incorporate a single fraction of GRID radiation in large (>8 cm), high-risk soft tissue and osteosarcomas prior to a standard fractionated course. Herein, we report on the excellent pathologic responses and apparent safety of this regimen in 26 consecutive patients.

[The clinical application of blood routine and liver and kidney function test in COVID-19 disease prediction]

Objective: To explore the clinical application value of routine indicators such as blood routine and liver and kidney function in auxiliary diagnosis and prognosis of COVID-19 patients. Methods: SNK-q and other methods were used to retrospectively analyzed the differences of blood routine test, liver and kidney function and other inflammatory indexes of 30 patients with covid-19, 29 patients with other viral pneumonia, 35 patients with influenza A/B and 25 healthy persons from January 28 to February 14, 2020 in Xiangya Hospital of Central South University. Results: The neutrophils count increased gradually in COVID-19 group, influenza A/B group and other types of viral pneumonia group, and the difference between COVID-19 group and other viral pneumonia groups was statistically significant(H=-19.064,P<0.05); The lymphocyte count decreased gradually in the control group, influenza A/B group, other viral pneumonia group and COVID-19 group. In addition, DB, UA and GLU were also different among groups. Subgroup analysis showed that there were statistically significant differences in N(F=9.581,t=-0.152,P<0.05), N%(F=5.723,t=-0.600, P<0.05), NLR(F=4.773, t=-1.161, P<0.05), PCT(F=17.464, t=-1.477, P<0.05)and CRP(F=7.656, t=-1.973, P<0.05) between patients with lung involvement +-++ and patients with lung involvement +++-++++. There were statistically significant differences in NLR(F=63.931, t=-2.815, P<0.01), AST(F=15.704, t=-1.930, P<0.01), ALT(F=35.551, t=-2.199, P<0.01), LDH(F=7.715, t=-2.703, P<0.05) and GLU(F=6.306, t=-5.116, P<0.05) between the light+common subgroup and the heavy+critical subgroup of COVID-19 clinical classification. Correlation analysis showed that clinical stage and imaging credit period were significantly correlated with NLR (r=0.406, P=0.026; r=0.397, P=0.030), ALT (r=0.403, P=0.049; r=0.418, P=0.047), LDH (r=0.543, P<0.01; r=0.643, P<0.01) and GLU(r=0.750, P<0.01; r=0.471, P=0.042). A total of 5 principal components were extracted from all the included indicators, and the comprehensive information extraction rate was 82.86%. Indicators of a large load included Ur, PCT and CRP in PC1; ALT, AST and GLU in PC2; N%, L%, L and NLR in PC3. It indicated that the indicators of acute infection, liver function and blood routine had certein warning effect on disease surveillance. The results of ROC curve analysis showed that the combined detection of N+TB+Urea was the best practice to distinguish COVID-19 and other viral pneumonia, while the combined detection of N+L+UA was the most effective solution to make a distinction between COVID-19 and influenza A/B patients. In the aspect of disease evaluation, NL+LDH+GLU+ALT combined detection represent the best diagnostic performance to distinguish the clinical stage of light+common type and heavy+critical type, achieving the AUC (ROC) to 0.904, with the sensitivity 75% and the specificity 100% at the cut-off value of 0.477. Conclusion: In addition to etiology and imaging examination, doctors can also improve the routine laboratory tests such as blood routine test, liver and kidney function to assist diagnosis and disease prediction of patients with respiratory tract infection.

[Clinical value of extended radical resection for pT3 stage gallbladder cancer]

Objective: To investigate the clinical value of extended radical resection for stage pT3 gallbladder cancer (GBC). Methods: The clinical and pathological data of 323 patients with stage pT3 GBC who received regional radical resection or extended radical resection in 7 domestic hepatobiliary centers in China from January 2013 to December 2018 were retrospectively analyzed. The propensity score matching method was used to select 36 cases in each of the regional radical resection group (group A1) and the extended radical resection group (group B1). The surgical indicators and overall survival rates of the two groups were compared, and prognostic factors were analyzed. Results: The number of positive lymph nodes [2(0,3)] and the total number of lymph nodes removed [3(1,4)] in group B1 were both higher than those in group A1 [1(0,1), 4(2,7)] (all P<0.05). There was no significant difference in other clinical and pathological factors between the two groups (all P>0.05). The 1, 3, and 5-year survival rates of group A1 were 75%, 44%, and 29%, respectively, which were significantly higher than those of group B1 of 50%, 15%, and 11% (χ(2)=11.311, all P<0.001). Extensive radical resection (HR=2.161, 95%CI: 1.222-3.821), hepatic parenchymal invasion (HR=2.324, 95%CI: 1.305-4.139), positive lymph node rate ≥1/3 (HR=2.927, 95%CI: 1.641-5.220), and ⅢB/ⅣB staging (HR=3.325, 95%CI: 1.750-6.320) are risk factors for the prognosis of GBC patients (all P<0.05), of which extended radical resection (HR=1.969, 95%CI: 1.083-3.581) was an independent risk factor for prognosis (P<0.05). When the ratio of positive lymph nodes was<1/3 and the tumor invaded the hepatic parenchyma, the overall survival rate of group B1 was significantly lower than that of group A1 (all P<0.05). Conclusions: The overall survival rate in patients with stage pT3 GBC whose lymph node positive rate<1/3 and/or hepatic parenchymal invaded cannot be improved by extended radical resection. Extended radical resection is an independent risk factor for patient prognosis.

[Construction and evaluation of a novel diagnosis pathway for 2019-Corona Virus Disease]

Objective: To construct and evaluate a diagnosis pathway (Xiangya pathway) for Corona Virus Disease 2019 (COVID-19). Methods: Consecutive subjects aged ≥12 years old who were screened for COVID-19 were included in Xiangya Hospital of Central South University from January 23 to February 3, 2020, and the subjects were further divided into the inception cohort and the validation cohort. The gender, age, onset time of disease of the subjects were recorded. The information of epidemiological history, fever, and the declined blood lymphocytes were collected as clinical indicators, CT scan was used to evaluate the possibility of COVID-19 and range of lung involvement. According to the current Chinese national standards, throat swabs of suspected cases were collected and the nucleic acid of COVID-19 was detected by reverse transcription-polymerase chain reaction (RT-PCR). The Xiangya pathway was constructed with multi-indexes, compared with clinical indicators, CT results and Chinese national standards, their effectiveness of detecting confirmed cases were verified in the inception and validation cohort. Results: A total of 382 consecutive adults who was screened for COVID-19 were included, and 261 cases were in the inception cohort and 121 cases were in the validation cohort. Among the 382 cases, 192 were males (50.3%) and 190 were females (49.7%), with a median age of 35 years (range: 15-92 years). There were 183 cases (47.9%) with epidemiological history, 275 cases (72.0%) with fever, 212 cases (55.5%) with decreased peripheral blood lymphocytes, 114 cases (29.8%) with positive CT findings, 43 cases (11.3%) with positive CT-COVID-19, and 30 cases (7.9%) with positive virus nucleic acid by throat swab. Compared with clinical indicators, the sensitivity and specificity of CT were 0.950 and 0.704, respectively. The accuracy of CT to make a definite diagnosis was higher than that of epidemiological history, fever, and declined blood lymphocyte count (0.809 vs 0.660, 0.532, 0.596, P=0.001, 0.002, 0.003, respectively). The sensitivity of this pathway and the pathway recommended by the Health Commission of China were both high (all were 1.000), while the specificity and accuracy of the Xiangya pathway were higher than the one recommended by the Health Commission (0.872 vs 0.765, 0.778 vs 0.592, both P<0.001). The CT-COVID-19 reduced the missed diagnosis rate caused by false negative of nucleic acid test (31 vs 64), with difference rate of 51.6%, and the positive rate of nucleic acid test was 64.5% (20/31). In validation cohort, the specificity and accuracy of the Xiangya pathway was 0.967, the positive rate of nucleic acid test was 76.9%(10/13). Conclusions: The Xiangya pathway can predict the nucleic acid test results of COVID-19, and can be applied as a reliable strategy to screen patients with suspected COVID-19 among people aged ≥12 years in areas other than Hubei during the epidemic period of COVID-19. The cohort size needs to be increased for further validation.

A practical cyberattack contingency plan for radiation oncology

Purpose

This article presents a solution for continuing radiation therapy without interruption in the event of a cyberattack to the radiation oncology information systems (ROIS). This process could be easily deployed to any radiation oncology practice, with little clinical overhead or burden.

Methods and Materials

The solution automatically retrieves all essential information from the clinical ROIS for each under‐treatment patient and periodically (e.g., daily) saves these data to a dedicated secure server for recovery. In the event that the clinical ROIS is not functioning as a result of a cyberattack, this essential information is used to build a new secondary ROIS server to continue radiotherapy treatments until the main ROIS is recovered. Once the cyberattack threat is cleared, the clinical ROIS server is rebuilt from the institution’s enterprise backup. The newly accumulated treatment information for each patient is then exported from the secondary ROIS to bring the clinical ROIS up to date.

Results

The Department of Radiation Oncology at the University of Maryland Medical System implemented this solution for clinical use with the Varian ARIA ROIS in the management of ~250 daily radiotherapy treatments, inclusive of a proton center. This solution was determined to be a feasible and affordable business continuity plan for the radiation oncology practice by minimizing radiation treatment downtime to a couple of hours in a simulated cyberattack drill.

Conclusions

The proposed solution can achieve continuation of radiation therapy treatment without treatment breaks in the event of a cyberattack. It also provides cushion time for radiation oncology departments to rebuild their clinical ROIS systems from the enterprise data backup.

EphrinB2/EphB4 Signaling Regulates DPSCs to Induce Sprouting Angiogenesis of Endothelial Cells

Dental pulp stem cells (DPSCs) are capable of facilitating angiogenesis resembling pericytes when located adjacent to endothelial cells (ECs). Nevertheless, the precise mechanisms orchestrating their proangiogenic functions remain unclear. Using a 3-dimensional (3-D) fibrin gel model, we aimed to investigate whether EphrinB2/EphB4 signaling in DPSCs plays a role in supporting vascular morphogenesis mediated by ECs, together with the underlying mechanism involved. The EphrinB2/EphB4 signaling was inhibited either by a pharmacological inhibitor of EphB4 receptor or by knocking down the expressions of EphrinB2 and EphB4 using lentiviral small hairpin RNA (shRNA). DPSCs were either encapsulated in fibrin gel together with human umbilical vein endothelial cells (HUVECs) or cultured as a monolayer on top of HUVECs to investigate both paracrine and juxtacrine interactions simultaneously. Following 10 d of direct coculture, we found that pharmacological inhibition of EphrinB2/EphB4 signaling severely impaired vessel formation and laminin deposition. When directly cocultured with HUVECs, knockdown of EphrinB2 or EphB4 in DPSCs significantly inhibited endothelial sprouting, resulting in less capillary sprouts with reduced vessel length (P < 0.05). By contrast, when DPSCs were not in direct contact with HUVECs, attenuation of EphrinB2 or EphB4 expression levels in DPSCs did not exert any significant effects on capillary morphogenesis. Noticeably, exogenous stimulation with soluble EphrinB2-Fc or EphB4-Fc (1 µg/mL) enhanced vascular endothelial growth factor (VEGF) secretion from DPSCs, thereby moderately promoting angiogenic cascades in the fibrin matrix. This study, for the first time, reveals a crucial role of EphrinB2/EphB4 signaling in regulating the capacity of DPSCs to induce sprouting angiogenesis. These findings advance our understanding of postnatal angiogenesis and may have future regenerative medicine applications.

[Accuracy analysis of computer assisted navigation for condylectomy via intraoral approach]

OBJECTIVE

To explore the application accuracy of virtual preoperative plan after the condylectomy via intraoral approach under computer assisted surgical navigation, and to analyze the location and cause of the surgical deviation to provide reference for the surgical procedure improvement in the future.

METHODS

In the study, 23 cases with condylar hypertrophy (11 with condylar osteochondroma and 12 with condylar benign hypertrophy) in Department of Oral and Maxilloficial Surgery, Peking University School and Hospital of Atomatology from December 2012 to December 2016 were treated by condylectomy via intraoral approach under computer assisted surgical navigation. The patient's spiral CT data were imported into ProPlan software before operation, and the affected mandibular ramus was reconstructed three-dimensionally. The condylar osteotomy line was designed according to the lesion range, and the preoperative design model was generated and introduced into the BrainLab navigation system. Under the guidance of computer navigation, the intraoral approach was used to complete the condylar resection according to the preoperative design of the osteotomy line. Cranial spiral CT of the craniofacial region was taken within one week after operation. three-dimensional reconstruction of the mandibular ramus at the condylectomy side was performed, and the condylar section was divided into six segments (anterolateral, anterior, anteromedial, posteromedial, posterior, and posterolateral) and the corresponding regional measurement points P1 to P6 were defined. Then the preoperative virtual model and the postoperative actual model were matched by Geomagic studio 12.0 to compare the differences and to analyze the accuracy of the operation.

RESULTS

All the patients had successfully accomplished the operation and obtained satisfactory results. Postoperative CT showed that the condyle lesion was completely resected, and the condylar osteotomy line was basically consistent with the surgical design. No tumor recurrence or temporomandibular joint ankylosis during the follow-up period. The postoperative accuracy analysis of the condylar resection showed that the confidence intervals measured by the six groups of P1 to P6 were (-2.26 mm, -1.89 mm), (-2.30 mm, -1.45 mm), (-3.37 mm, -2.91 mm), (-2.83 mm, -1.75 mm), (-1.13 mm, 0.99 mm), and(-1.17 mm, 0.17 mm), where P3 group was different from the other 5 groups. There was no significant difference between the P5 and P6 groups and the difference between the other four groups was statistically significant.

CONCLUSION

Under the guidance of computer navigation, the intraoral approach can be performed more accurately. The surgical deviation of each part of the osteotomy surface is mainly due to excessive resection. The anterior medial area of the anterior medial condyle represents the most excessive resection. The posterior and posterior lateral measurement points represent the posterior condylar area. The average deviation is not large, but the fluctuation of the deviation value is larger than that of the other four groups. The accuracy of computer-assisted subtotal resection has yet to be improved.

Abstract P2-01-24: Sulindac and triple negative breast cancer progression

In 2018, a total of 266,120 new cases and 40,920 deaths from breast cancer in the United States were estimated by the American Cancer Society. Breast cancer is the most common malignancy and the second leading cause of death among American women. In this study, we will focus on triple negative breast cancer (TNBC), which is viewed by oncologists as a problematic and unpredictable sub-category of breast cancer because of higher rates of recurrence and poorer prognosis. TNBC accounts for up to 20% of all breast cancers and is highly prevalent in minority and young women. On average, 70% of women with metastatic TNBC die within 5 years, regardless of chemotherapy or other treatments. As such, there is an urgent medical need to develop more effective drugs to manage this deadly disease that already raised a health disparity concern, especially in the State of Louisiana. Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used drugs for the treatment of pain, fever, and inflammation. Epidemiological studies have reported that the long term use of NSAIDs can prevent the occurrence multiple types of cancers, including breast cancer. However, their long term use for chemoprevention is not recommended because of toxicities associated with cyclooxygenase (COX) inhibition and the suppression of physiologically important prostaglandins. Our results show that the NSAID, sulindac sulfide (SS) and its non-COX inhibitory derivatives, can significantly inhibit the growth of the major subtypes of TNBC cells (basal-like, mesenchymal, and luminal). In addition, the compounds significantly inhibit tumor cell invasion. The animal experiments using Patient Derived Xenograft models supported the in vivo efficacy of these drugs. While studying the mechanism, we found that four oncogenic miRNAs, miR-10b, miR-17, miR-21, and miR-9 can be downregulated by SS and derivatives, and they were reported to promote tumor metastasis exclusively. Therefore, we conclude that those oncogenic miRNAs are involved in anti-metastatic activities of SS and its new non-COX inhibitory derivatives in TNBC.

Citation Format: Xi Y, Yi B, Riker A. Sulindac and triple negative breast cancer progression [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-01-24.

Action Levels on Dose and Anatomic Variation for Adaptive Radiation Therapy Using Daily Offline Plan Evaluation: Preliminary Results

PURPOSE

This study aimed to develop action levels for replanning to accommodate dosimetric variations resulting from anatomic changes during the course of treatments, using daily cone beam computed tomography (CBCT).

METHODS AND MATERIALS

Daily or weekly CBCT images of 20 patients (10 head and neck, 5 lung, and 5 prostate cancers) who underwent resimulation per physicians' clinical decisions, mainly from the comparison of CBCT scans, were used to determine action levels. The first CBCT image acquired before the first treatment was used as the reference image to rule out effects of dose inaccuracy from the CBCT. The Pearson correlation of clinical target volume (CTV) was used as a parameter of anatomic variation. Parameters for action levels on dose and anatomic variation were deduced by comparing the parameters and clinical decisions made for replanning. A software tool was developed to automatically perform all procedures, including dose calculations, using the CBCT and plan evaluations.

RESULTS

Replans were clinically decided based on either significant dose or anatomic changes in 13 cases. The 7 cases that did not require replanning showed dose differences <5%, and the Pearson correlation of the CTV was >75% for all fractions. A difference in planning target volume dose >5% or a difference in the image correlation coefficient of the CTV <0.75 proved to be indicators for replanning. Once the results of the CBCT plan met the replanning criteria, the software tool automatically alerted the attending physician and physicist by both e-mail and pager so that the case could be examined closely.

CONCLUSIONS

Our study shows that a dose difference of 5% and/or anatomy variation at 0.75 Pearson correlations are practical action levels on dose and anatomic variation for replanning for the given data sets.

A Novel Method of Cone Beam CT Projection Binning Based on Image Registration

Accurate sorting of beam projections is important in 4D cone beam computed tomography (4D CBCT) to improve the quality of the reconstructed 4D CBCT image by removing motion-induced artifacts. We propose image registration-based projection binning (IRPB), a novel marker-less binning method for 4D CBCT projections, which combines intensity-based feature point detection and trajectory tracking using random sample consensus. IRPB extracts breathing motion and phases by analyzing tissue feature point trajectories. We conducted experiments with two phantom and six patient datasets, including both regular and irregular respirations. In experiments, we compared the performance of the proposed IRPB, Amsterdam Shroud method (AS), Fourier transform-based method (FT), and local intensity feature tracking method (LIFT). The results showed that the average absolute phase shift of IRPB was 3.74 projections and 0.48 projections less than that of FT and LIFT, respectively. AS lost the most breathing cycles in the respiration extraction for the five patient datasets, so we could not compare the average absolute phase shift between IRPB and AS. Based on the peak signal-to-noise ratio (PSNR) of the reconstructed 4D CBCT images, IRPB had 5.08, 1.05, and 2.90 dB larger PSNR than AS, FT, and LIFT, respectively. The average Structure SIMilarity Index (SSIM) of the 4D CBCT image reconstructed by IRPB, AS, and LIFT were 0.87, 0.74, 0.84, and 0.70, respectively. These results demonstrated that IRPB has superior performance to the other standard methods.

Planning 4D intensity-modulated arc therapy for tumor tracking with a multileaf collimator

This study introduces a practical four-dimensional (4D) planning scheme of IMAT using 4D computed tomography (4D CT) for planning tumor tracking with dynamic multileaf beam collimation. We assume that patients can breathe regularly, i.e. the same way as during 4D CT with an unchanged period and amplitude, and that the start of 4D-IMAT delivery can be synchronized with a designated respiratory phase. Each control point of the IMAT-delivery process can be associated with an image set of 4D CT at a specified respiratory phase. Target is contoured at each respiratory phase without a motion-induced margin. A 3D-IMAT plan is first optimized on a reference-phase image set of 4D CT. Then, based on the projections of the planning target volume in the beam's eye view at different respiratory phases, a 4D-IMAT plan is generated by transforming the segments of the optimized 3D plan by using a direct aperture deformation method. Compensation for both translational and deformable tumor motion is accomplished, and the smooth delivery of the transformed plan is ensured by forcing connectivity between adjacent angles (control points). It is envisioned that the resultant plans can be delivered accurately using the dose rate regulated tracking method which handles breathing irregularities (Yi et al 2008 Med. Phys. 35 3955-62).This planning process is straightforward and only adds a small step to current clinical 3D planning practice. Our 4D planning scheme was tested on three cases to evaluate dosimetric benefits. The created 4D-IMAT plans showed similar dose distributions as compared with the 3D-IMAT plans on a single static phase, indicating that our method is capable of eliminating the dosimetric effects of breathing induced target motion. Compared to the 3D-IMAT plans with large treatment margins encompassing respiratory motion, our 4D-IMAT plans reduced radiation doses to surrounding normal organs and tissues.

[Relationship between weather factors and heat stroke in Ningbo city]

OBJECTIVE

To explore the main effects of weather factors on heat stroke.

METHODS

Data from case report on heat stroke was collected in Ningbo city during 2011 to 2014. Temperature threshold, lag effects and interaction of weather factors on heat stroke had been analyzed, using the piecewise regression model, distributed lag non-linear model, response surface model and other methods.

RESULTS

RESULTS showed that temperature and humidity were more correlated with heat stroke than other weather-related factors. Through different models, daily average temperature always presented a better role in predicting the heat stroke, rather than maximum or minimum temperature. Positive association between daily average temperature and heat stroke was obvious, especially at lag 0-1 days, with its threshold as 29.1 (95% CI: 28.7-29.5) ℃ . The cumulative RR of heat stroke at 90(th) percentile of daily average temperature versus 10(th) percentile was 14.05 (95% CI: 7.23-27.31) in lag 0-1 days. The effects of daily relative humidity on heat stroke appeared nonlinear, with low humidity showing a negative effect on heat stroke and could lag for 1-4 days. However, the effect of high humidity was not significant, with the cumulative RR of low humidity and high humidity as 2.35 (95%CI: 1.27-4.33) and 0.86 (95%CI: 0.40-1.85) in lag of 0-4 days, respectively. We also noticed that there was an interactive effect of both temperature and humidity on heat stroke. Under high temperature and low humidity, the risk of heat stroke showed the highest.

CONCLUSIONS

Temperature and humidity showed obvious relationship with heat stroke in Ningbo city, with the threshold temperature as 29.1 ℃. Under high temperature and low humidity, the risk of heat stroke became the highest.

Improving Delivery Accuracy of Stereotactic Body Radiotherapy to a Moving Tumor Using Simplified Volumetric Modulated Arc Therapy

PURPOSE

To develop a simplified volumetric modulated arc therapy (VMAT) technique for more accurate dose delivery in thoracic stereotactic body radiation therapy (SBRT).

METHODS AND MATERIALS

For each of the 22 lung SBRT cases treated with respiratory-gated VMAT, a dose rate modulated arc therapy (DrMAT) plan was retrospectively generated. A dynamic conformal arc therapy plan with 33 adjoining coplanar arcs was designed and their beam weights were optimized by an inverse planning process. All sub-arc beams were converted into a series of control points with varying MLC segment and dose rates and merged into an arc beam for a DrMAT plan. The plan quality of original VMAT and DrMAT was compared in terms of target coverage, compactness of dose distribution, and dose sparing of organs at risk. To assess the delivery accuracy, the VMAT and DrMAT plans were delivered to a motion phantom programmed with the corresponding patients' respiratory signal; results were compared using film dosimetry with gamma analysis.

RESULTS

The plan quality of DrMAT was equivalent to that of VMAT in terms of target coverage, dose compactness, and dose sparing for the normal lung. In dose sparing for other critical organs, DrMAT was less effective than VMAT for the spinal cord, heart, and esophagus while being well within the limits specified by the Radiation Therapy Oncology Group. Delivery accuracy of DrMAT to a moving target was similar to that of VMAT using a gamma criterion of 2%/2mm but was significantly better using a 2%/1mm criterion, implying the superiority of DrMAT over VMAT in SBRT for thoracic/abdominal tumors with respiratory movement.

CONCLUSION

We developed a DrMAT technique for SBRT that produces plans of a quality similar to that achieved with VMAT but with better delivery accuracy. This technique is well-suited for small tumors with motion uncertainty.

[Feasibility of integrating 3D photos and cone-beam computed tomography images used to evaluate changes of soft and hard tissue after orthognathic surgery]

OBJECTIVE

To evaluate the feasibility of integrating 3D photos and cone-beam computed tomography (CBCT) images and to assess the degree of error that may occur during the above process, and to analyze soft and hard tissue changes after orthognathic surgery using this new method.

METHODS

Ten patients with maxillofacial deformities were chosen. For each patient, CBCT scans and stereophotographic images were taken before and 3 months after surgery. 3D photos were superimposed onto the CBCT skin images using relatively immobile areas of the face as a reference. 3D color maps and mean distances were used to evaluate the errors that might occur during the process. Two reference planes were set up using certain points. The distances between Prn (pronasale),Sn (subnasale),Ls (labrale superior),ANS (anterior nasal spine),A (subspinale),UIE (upper incisor edge) to the coronal plane were calculated before and after surgery. In order to verify the repeatability of this method, we examined the distances twice at two-week intervals. Paired t test was used to evaluate the reproducibility.

RESULTS

CBCT and 3D photos could be successfully fused with clinically acceptable errors. This new method could be used to evaluate soft and hard tissue changes after orthognathic surgery. The 3D color maps showed that the two images could be fused with minimal errors. The mean distances were within 0.3 mm, and the locations of landmarks on maxilla and mandible such as Ls, ANS, A, UIE changed significantly after orthognathic surgery (P<0.05).Landmarks on the nose such as Prn,Sn had little changes after surgery (P>0.1). The paired t test showed that the mean value and standard deviation were (0.08±0.98) mm.

CONCLUSION

Fusing of CBCT and 3D stereophotographic images used as a new method in evaluating soft and hard tissue changes after orthognathic surgery was feasible and accurate. The virtual 3D composite craniofacial models permitted concurrent assessment of hard and soft tissues during diagnosis and treatment planning. Maxillary and mandibular locations had significant association with orthoganthic surgery while the nasal tissue was not simp affected by surgery.

[Transpalatal modified Le Fort I osteotomy for correction of maxillary hypoplasia in cleft lip and palate patients: a preliminary clinical application]

OBJECTIVE

To evaluate the surgical corrective results of maxillary hypoplasia in patients with cleft lip and palate withtranspalatal modified Le Fort I osteotomy.

METHODS

In the study, 11 patients (4 women, and 7 men) with maxillary hypoplasia secondary to cleft lip and palate underwent transpalatal modified Le Fort I osteotomy at Peking University School of Stomatology from Jan. 2012 to Dec. 2013,with the mean age of 21 years ( from 18 to 27 years), Bilateral sagittal split ramus osteotomy (BSSRO)and genioplasty were performed simultaneously in 9 of them for better appearance and functional occlusion. Lateral cephalometric radiographs were taken and traced before surgery, immediately after surgery and 6 months after surgery. The position of subspinale (A) on horizontal direction, the angle of sella-nasion-subsipmale (SNA) and the angle of sella-nasion-supramental (SNB) were collected and analyzed to evaluate the results.

RESULTS

All the patients were uneventful with transpalatal modified Le Fort I osteotomy. All of them had a better profile and a satisfactory occlusionafter operation.The position of A was moved forward (6.6±1.1) mm on average in horizontal direction when surgery was completed, and maintained (6.0±1.2) mm on average 6 months after surgery. The average of SNA was 75.9°±2.8° before surgery,81.6°±8.6° immediately after surgery, and maintained 81.0°±2.6° 6 months after surgery. The average of SNB was 82.6°±3.7° before surgery, 78.0°±2.4° immediately after surgery, and maintained 78.5°±2.4° 6 months after surgery.

CONCLUSION

The maxillary hypoplasia in cleft lip and palate patients can be successfully corrected with transpalatal modified Le Fort I osteotomy and the functional occlusion can be achieved simultaneously. The effect of deformity correction was satisfactory. Transpalatal modified Le Fort I osteotomy can move maxilla more sufficiently, especially applicable for the patient with severe palatal scars preoperatively.

[Imaging analysis of temporomandibular joint anatomy changes after intraoral condylectomy combined with orthognathic surgery]

OBJECTIVE

To quantitatively analyze the changes of facial symmetry and temporomandibular joint structure at different periods after intraoral condylectomy combined with orthognathic surgery, and to evaluate the long-term stability after the operation.

METHODS

Spiral CT data of 10 cases treated by intraoral condylectomy combined with orthognathic surgery were collected, and then reconstructed by ProPlan software. Mark points were drawn on the 3D-images reconstructed immediately after the operation, and 6 months and 12 months after the operation. The measurements parameters included condylar axis angle in three dimensions, condylar-glenoid relative position and condylar facial morphology related indicators. The results were statistically analyzed by the consistency test and the variance of repeated measurement data.

RESULTS

The facial asymmetry of the patients was corrected after operation, the height of the affected mandibular ascending ramus(T1: [67.81±6.95]mm, T2: [64.49±6.24]mm, T3: [63.05±7.07]mm)as well as the degree of pogonion deviation decreased(T1: [2.79±4.93]mm, T2: [0.37±4.20]mm, T3: [0.33 ± 3.97]mm)(P<0.05). But the tilt angle of the occlusion plane and the degree of mandibular height asymmetry had no significant difference between all the post-operative periods(P>0.05). The post-operative 3D changes of the position and shape of the resected and its contralateral condylar showed that the bilateral condylar axis angle in the horizontal plane gradually grew after operation(affected condyle: 71.95° ± 7.47°, 74.73°±8.44°, 76.56°±5.22°; control condyle: 72.60°±5.56°, 76.00°±5.30°, 77.19°±6.20° and had significant difference between all the post-operative periods)(P<0.05), the condyle moved slowly upward on both sides(superior space on the affected side: [8.78±4.38]mm, [4.11±2.49]mm, [3.27±1.96]mm; on the control side: [3.63±1.49]mm, [2.52±1.19]mm, [2.38±1.11]mm)(P<0.05), and moved inward only on the affected side(P< 0.05). All the above changes slowed down over time, and the disc-condyle-fossa relative position tended to be stable over time as well. The condyle diameter on the inside-outside direction gradually decreased on the affected side(T1: [14.98±2.39]mm, T2: [14.04±2.68]mm, T3: [13.74±2.89]mm)(P<0.05), and the surface morphology of the resected condyle was similar to the normal side. There were also some condylar surface morphological changes on the control side, but no statistical significance was found between different periods after the peration(P>0.05).

CONCLUSIONS

The intraoral condylectomy combined with orthognathic surgery can eliminate condylar lesions effectively and correct the facial asymmetry caused by condylar benign tumor and hyperplasia. The facial symmetry can be maintained well after the operation, and the post-operative condylar morphology changes tended to be stable six months after the operation.