A feasibility trial of skin surface motion-gated stereotactic body radiotherapy for treatment of upper abdominal or lower thoracic targets using a novel O-ring gantry

Background and purpose

A novel O-ring gantry can deliver stereotactic body radiation therapy (SBRT) with artificial intelligence-facilitated, CT-guided online plan adaptation. It gates mobile targets by optically monitoring skin surface motion. However, this gating solution has not been clinically validated. We conducted a trial to evaluate the feasibility of optical skin surface-guided gating for patients with mobile upper abdominal or lower thoracic malignancies treated with SBRT on this platform (NCT05030454).

Materials and methods

Ten patients who were prescribed SBRT to a thoracic or abdominal target and were capable of breath-hold for at least 17 s enrolled. They received SBRT in five fractions with breath-hold technique and optical skin surface motion monitored-gating with a ± 2 mm tolerance. Online plan adaptation was left to the discretion of the daily treating physician. The primary endpoint was defined as successful completion of > 75 % of attempted fractions. Exploratory endpoints included local control and acute grade ≥ 3 toxicity rates after three months. For adapted fractions the contouring, planning, quality assurance, and treatment delivery times were recorded.

Results

Forty-seven of 51 SBRT fractions (92 %) were successfully gated at breath-hold by optical skin surface motion monitoring. The tumor centroid position during breath-hold varied by a mean of approximately 2 mm. Sixty-three percent of fractions were adapted online with a median total treatment time of 78.5 min. After three months no local recurrences or acute grade ≥ 3 toxicities were observed.

Conclusions

SBRT treatment to mobile targets with surface-monitored gating on a novel O-ring gantry was prospectively validated.

A Dose Accumulation Assessment of Alignment Errors During Spatially Fractionated Radiation Therapy

PURPOSE

Spatially fractionated radiation therapy (SFRT) techniques produce high-dose peaks and low-dose valleys within a tumor. Lattice stereotactic body radiation therapy (SBRT) is a form a SFRT delivered across 5 fractions. Because of the high spatial dose gradients associated with SFRT, it is critical for fractionated SFRT patients to be aligned correctly for treatment. Here we investigate the dosimetric effect of daily alignment uncertainty through a dose accumulation study.

METHODS AND MATERIALS

Dose accumulation was retrospectively performed for 10 patients enrolled on a phase 1 trial. Lattice stereotactic body radiation therapy was completed in 5 fractions with 20 Gy prescribed to the entire tumor and a simultaneous integrated boost of 66.7 Gy prescribed to a set of regularly spaced high-dose spheres. Daily alignment error was quantified through manually selected landmarks in both the planning computed tomography scan and daily cone beam computed tomography. The dosimetric effect of alignment errors was quantified by translating the isocenter in the treatment planning system by the daily average alignment error. Large errors were simulated by translating isocenter 5 and 10 mm for 1 and 2 fractions, independently assessing errors in the superior-inferior and axial directions. The reduction of dose gradients was quantified using the dose ratio (DR) of the mean dose in the high-dose and low-dose spheres.

RESULTS

The average alignment error was 1.8 mm across the patient population resulting in minor smoothing of the high- and low-dose distributions in the dose accumulation. Quantitatively, the DR decreased from 3.42 to 3.32 (P = .093) in the dose accumulation study. The simulated worst case was an inferior-superior shift of 10 mm for 2 fractions where the average DR decreased to 2.72 (P = .0001).

CONCLUSIONS

The dose accumulation study revealed on average DR only decreased from 3.42 to 3.32. However, setup errors >5 mm resulted in larger dosimetric degradation, reflecting a larger effect for individual high-dose spheres within regions exhibiting larger displacements.

NRG-DT001 phase Ib trial of neoadjuvant navtemadlin (previously AMG232 and KRT232) concurrent with preoperative radiotherapy in wild-type p53 soft tissue sarcoma of the extremity and body wall

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Background: NRG-DT001 is a phase Ib trial evaluating neoadjuvant navtemadlin with preoperative radiation therapy (RT) in patients (pts) with wild-type (WT) p53 soft tissue sarcoma (STS). The primary objective is to evaluate the safety and tolerability of the MDM2 inhibitor navtemadlin in combination with standard-dose RT in STS in two cohorts (A, extremity or body wall; B, abdomen/pelvis/retroperitoneum) to determine the maximum tolerated dose/recommended phase II dose (MTD/RP2D) of navtemadlin in combination with RT. This report contains the results for cohort A. Methods: Eligible pts had grade 2-3 STS ≥ 5 cm, age ≥ 18, and Zubrod performance status 0-1. Dose levels were 120 mg 2x/week (DL-1), 120 mg 3x/week (DL1), 4x/week (DL2), and 5x/week (DL3) 1 week prior to and during RT (50Gy/5 weeks). Surgery was 5-8 weeks after RT. A 3+3 design was used to make dose escalation/de-escalation decisions at each dose level. Five additional pts were enrolled to the MTD to ensure safety (expansion cohort) with a dose limiting toxicity (DLT) rate of ≤ 1/5 considered safe. The DLT observation period was from the start of navtemadlin until 4 weeks after completion of drug+RT. Tumor Tp53 mutation status was determined by NGS sequencing. All eligible and treated p53 WT pts who experienced DLT or completed the observation period were considered DLT-evaluable. DLT included all grade 4-5 AE definitely, probably, or possibly related to navtemadlin. Any grade 3 AE definitely, probably, or possibly related to navtemadlin was also considered DLT if any of the 2 following situations occurred: a delay of treatment > 2 weeks or ≥ 2 dose reductions due to the grade 3 AE. The decision to escalate or de-escalate was made by consensus of the study team in accordance with the protocol. Results: Between 11/3/2017 and 9/10/2021, 4 (3 WT), 7 (4 WT) and 7 (4 WT) pts were enrolled at DL1, DL2, and DL3 respectively. An additional 9 (5 WT) pts were enrolled on DL3 expansion cohort. Preoperative RT was completed for all except 1 pt (pt refusal/DL3). On DL1 and DL2, 100% of pts completed navtemadlin. On DL3 (including expansion cohort), 78% (7/9) completed navtemadlin (1 AE, 1 pt refusal). On DL1, DL2, and DL3, 3/3, 3/4 (1 disease progression), and 5/6 (1 consent withdrawal; 3 pending) completed surgery. There were no DLTs in any dose level (DL1 0/3, DL2 0/4, DL3 0/9), establishing DL3 as the MTD/RP2D. Tumor necrosis rates will be reported at the time of presentation. Conclusions: Neoadjuvant navtemadlin concurrent with standard dose preoperative RT is well tolerated in patients with WT p53 STS at extremity or body wall, and the 120 mg PO daily of navtemadlin, 5 days per week dose should be used to design future trials of RT with extremity STS. Incorporating NGS sequencing results as an integral biomarker in a clinical trial of neoadjuvant radiotherapy and a radiosensitizer is feasible. Clinical trial information: NRG-DT001 NCT03217266.

A single-institution phase I feasibility study of dose-escalated IMRT for non-operative locally advanced esophageal carcinoma

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Dose escalation with IMRT to 60 Gy for esophageal cancer is feasible.

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Dose escalation with cisplatin/5-FU still results in significant toxicity.

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Improved local control, but comparable survival compared to historical controls.

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Pretreatment weight loss was found to be an independent predictor of poor survival.

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Our dose escalation study is one of few with predominant adenocarcinoma histology.

Background and purpose

Radiation dose escalation to improve poor outcomes with chemoradiation in locally advanced esophageal carcinoma is limited in part by increased toxicity. This Phase I study investigates the use of IMRT to improve tolerability of dose escalation.

Materials and methods

A single-institution, prospective study was conducted between 2007 and 2013 for individuals with inoperable esophageal carcinoma. Gross disease received 60 Gy in 30 fractions and at-risk sites received 54 Gy with simultaneous integrated boost. Concurrent chemotherapy primarily consisted of cisplatin/5-FU. The primary objective was to assess feasibility (<15% rate of grade 4–5 toxicity). Secondary objectives included assessment of overall survival (OS), progression free survival (PFS), and locoregional (LRR) and distant recurrence.

Results

Twenty-six patients were enrolled with median follow up of 17.6 months (range 0.1 to 152.0). The majority were AJCC 7th edition Stage III (54%), distal esophagus primary (81%), and adenocarcinoma histology (85%). Twenty-one patients (81%) completed their course of radiation therapy, while only 55% received 2 cycles of concurrent cisplatin/5-FU. One grade 5 and one grade 4 cardiac event occurred, both during chemoradiation and before receiving 50 Gy. The 3-year OS was 48.6% (95% CI: 32.5 to 72.2%) and PFS was 28.5% (95% CI: 14.6 to 55.5%). Half developed distant failure with LRR occurring in 10 patients (38%), isolated in 5 patients.

Conclusion

While feasibility was demonstrated, toxicity and compliance remained limiting factors with outcomes similar to historical controls. There remains an uncertain role for dose escalation in definitive management of locally advanced esophageal cancer.

Are we making an impact with incident learning systems? Analysis of quality improvement interventions using total body irradiation as a model system

PURPOSE

Despite increasing interest in incident learning systems (ILS) to improve safety and quality in radiation oncology, little is known about interventions developed in response to safety data. We used total body irradiation (TBI) as a model system to study the effectiveness of interventions from our institutional ILS.

METHODS AND MATERIALS

Near-miss event reports specific to TBI were identified from a departmental ILS from March 2012 to December 2015. The near-miss risk index was rated at multidisciplinary review from 0 (no potential harm) to 4 (critical potential harm). Interventions were analyzed for effectiveness with a schema adapted from The Joint Commission and other agencies: "most reliable" (eg, forcing functions, automation), "somewhat reliable" (eg, checklists, standardization), and "least reliable" (eg, training, rules, procedures). Causal factors of each event were drawn from the casual factor schema used in radiation oncology ILS.

RESULTS

Of 4007 safety-related reports, 266 reports pertained to TBI. TBI reports had a somewhat higher proportion of high-risk events (near-miss risk index 3-4) compared with non-TBI reports (25% vs 17%, P = .0045). A total of 117 interventions were implemented. The reliability indicators for the interventions were: most reliable (11% of interventions), somewhat reliable (17%), and least reliable (72%). Interventions were more likely to be applied to high-risk events (54% vs 41%, P = .03). There was a pattern of high-reliability interventions with increased risk score of events. Events involving human error (eg, slips) and equipment/information technology lent themselves more often to high-reliability interventions. Events related to communication, standardization, and training were associated with low-reliability interventions.

CONCLUSIONS

Over a 3.5-year period, 117 quality improvement strategies were developed for TBI based on ILS. Interventions were more likely to be applied to high-risk events and high-risk events were more likely to be associated with high-quality interventions. These results may be useful to institutions seeking to develop interventions based on ILS data.

Eta' photoproduction on the proton for photon energies from 1.527 to 2.227 GeV

Differential cross sections for the reaction gamma p --> eta' p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the eta'N channel to both the S11(1535) and P11(1710) resonances, known to couple strongly to the etaN channel in photoproduction on the proton, and the importance of J = 3/2 resonances in the process.

Onset of asymptotic scaling in deuteron photodisintegration

We investigate the transition from the nucleon-meson to the quark-gluon description of the strong interaction using the photon energy dependence of the d(gamma,p)n differential cross section for photon energies above 0.5 GeV and center-of-mass proton angles between 30 degrees and 150 degrees. A possible signature for this transition is the onset of cross-section s(-11) scaling with the total energy squared, s, at some proton transverse momentum P(T). The results show that the scaling has been reached for proton transverse momentum above about 1.1 GeV/c. This may indicate that the quark-gluon regime is reached above this momentum.

Proton source size measurements in the eA-->e'ppX reaction

Two-proton correlations at small relative momentum q were studied in the eA(3He,4He,C,Fe)-->e(')ppX reaction at E(0)=4.46 GeV using the CLAS detector at Jefferson Lab. The enhancement of the correlation function at small q was found to be in accordance with theoretical expectations. Sizes of the emission region were extracted, and proved to be dependent on A and on the proton momentum. The size of the two-proton emission region for He was measured in eA reactions for the first time.

Two-nucleon momentum distributions measured in 3He(e,e'pp)n

We have measured the 3He(e,e'pp)n reaction at 2.2 GeV over a wide kinematic range. The kinetic energy distribution for "fast" nucleons (p>250 MeV/c) peaks where two nucleons each have 20% or less, and the third nucleon has most of the transferred energy. These fast pp and pn pairs are back to back with little momentum along the three-momentum transfer, indicating that they are spectators. Calculations by Sargsian and by Laget also indicate that we have measured distorted two-nucleon momentum distributions by striking one nucleon and detecting the spectator correlated pair.

Observation of an exotic baryon with S=+1 in photoproduction from the proton

The reaction gamma p-->pi(+)K(-)K(+)n was studied at Jefferson Laboratory using a tagged photon beam with an energy range of 3-5.47 GeV. A narrow baryon state with strangeness S=+1 and mass M=1555+/-10 MeV/c(2) was observed in the nK(+) invariant mass spectrum. The peak's width is consistent with the CLAS resolution (FWHM=26 MeV/c(2)), and its statistical significance is (7.8+/-1.0)sigma. A baryon with positive strangeness has exotic structure and cannot be described in the framework of the naive constituent quark model. The mass of the observed state is consistent with the mass predicted by the chiral soliton model for the Theta(+) baryon. In addition, the pK(+) invariant mass distribution was analyzed in the reaction gamma p-->K(-)K(+)p with high statistics in search of doubly charged exotic baryon states. No resonance structures were found in this spectrum.

Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS

Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value.

Measurement of ep-->e' ppi+ pi- and baryon resonance analysis

The cross section for the reaction ep-->e(')ppi(+)pi(-) was measured in the resonance region for 1.4<W<2.1 GeV and 0.5<Q2<1.5 GeV(2)/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N(*) and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

First measurement of transferred polarization in the exclusive ep-->e'K+Lambda--> reaction

The first measurements of the transferred polarization for the exclusive e-->p-->e(')K+Lambda--> reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567 GeV beam was used to measure the hyperon polarization over Q2 from 0.3 to 1.5 (GeV/c)(2), W from 1.6 to 2.15 GeV, and over the full K+ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A nonrelativistic quark-model interpretation of our data suggests that the ssmacr; quark pair is produced with spins predominantly antialigned. Implications for the validity of the most widely used quark-pair creation operator are discussed.

Photoproduction of the omega meson on the proton at large momentum transfer

The differential cross section, dsigma/dt, for omega meson exclusive photoproduction on the proton above the resonance region (2.6<W<2.9 GeV) was measured up to a momentum transfer -t=5 GeV2 using the CLAS detector at Jefferson Laboratory. The omega channel was identified by detecting a proton and pi(+) in the final state and using the missing mass technique. While the low momentum transfer region shows the typical diffractive pattern expected from Pomeron and Reggeon exchange, at large -t the differential cross section has a flat behavior. This feature can be explained by introducing quark interchange processes in addition to the QCD-inspired two-gluon exchange.

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

First measurement of the double spin asymmetry in (-->)e(-->)p-->e(prime)pi(+)n in the resonance region

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

Photoproduction of the rho(0) meson on the proton at large momentum transfer

The differential cross section, d sigma/dt, for rho(0) meson photoproduction on the proton above the resonance region was measured up to a momentum transfer -t = 5 GeV2 using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The rho(0) channel was extracted from the measured two charged-pion cross sections by fitting the pi(+)pi(-) and p pi(+) invariant masses. The low momentum transfer region shows the typical diffractive pattern expected from Reggeon exchange. The flatter behavior at large -t cannot be explained solely in terms of QCD-inspired two-gluon exchange models. The data indicate that other processes, like quark interchange, are important to fully describe rho photoproduction.

Effects of breathable disposable diapers: reduced prevalence of Candida and common diaper dermatitis

Infants wearing breathable disposable diapers experienced significantly less diaper dermatitis (DD) compared to infants wearing standard, nonbreathable disposable diapers in a series of double-blind clinical trials. Severe DD, including confirmed infection with Candida albicans, was reduced by 38-50% among infants wearing highly breathable (HB) diapers. The prevalence of DD was inversely related to the breathability of the garments. The inhibitory effect of breathable diapers on the survival of Candida was further confirmed in controlled experiments with adult volunteers. A suspension of C. albicans cells was applied to delineated sites on the volar forearm. Each site was then covered by a full-thickness patch from either an HB or a standard diaper. Survival of Candida colonies was reduced by almost two-thirds in the breathable diaper-covered sites compared to the control sites.

The ep -->e'p eta reaction at and above the S11(1535) baryon resonance

New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

Aleukemic leukemia cutis: juvenile chronic granulocytic leukemia presenting with figurate cutaneous lesions

We report a 3 1/2-year-old girl who developed a figurate cutaneous eruption. Distinctive findings in her skin biopsies, as well as unusual red cell characteristics, in the presence of a normal peripheral smear and bone marrow biopsy, led us to suspect the diagnosis of preleukemic juvenile type chronic granulocytic leukemia. This is the first case we know of in which this diagnosis was suspected prior to abnormal findings in the peripheral smear or bone marrow.