Dose escalation study with respiratory-gated carbon-ion scanning radiotherapy using a simultaneous integrated boost for pancreatic cancer: simulation with four-dimensional computed tomography

OBJECTIVE

Pancreatic cancer is a difficult to treat disease with a persistently high mortality rate. We evaluated dose distribution simulation with respiratory-gated carbon-ion pencil beam scanning (C-PBS) with a simultaneous integrated boost (SIB) to increase tumour dose, sparing organs at risk (OARs).

METHODS

Using four-dimensional CT data of 12 patients, we delineated gross tumour volume and two clinical target volumes (CTVs). To consider beam range intrafractional uncertainty, we calculated field-specific target volumes, from which two planning target volumes (PTVs) were generated. PTV1 would receive a planned dose of 55.2 Gy [relative biological effectiveness (RBE)-weighted absorbed dose] in 12 fractions, and PTV2 would receive an SIB dose up to 67.2 Gy (RBE). Dose assessments were conducted with regard to the targets and OARs.

RESULTS

CTV2 dose covering 95% of the volume (D_95%) increased from 50.3 ± 5.1 Gy (RBE) to 62.5 ± 3.5 Gy (RBE) for a planned dose from 55.2 Gy (RBE) to 67.2 Gy (RBE). For 4 of 12 patients with a distance of ≥5 mm between the tumour and the gastrointestinal tract, CTV2 D_95% was ≥95% of planned dose at all dose levels.

CONCLUSION

We quantified dose escalation with respiratory-gated C-PBS using SIB for pancreatic cancer and revealed that OAR dose was not affected to the same degree as the tumour dose. Advances in knowledge: A simulation study on respiratory-gated C-PBS with SIB for pancreatic cancer was performed. The results indicated the feasibility of dose escalation for pancreatic cancer, which should be confirmed in clinical trials.

Regulatory T cells function at the early stage of tumor progression in a mouse model of tongue squamous cell carcinoma

The objective of this study was to observe the distribution of regulatory T cells (Tregs) in the development of tongue squamous cell carcinoma (SCC) and to determine the role of Tregs in the progression of tongue SCC. A mouse model of 4-nitroquinoline-1-oxide (4NQO)-induced-tongue SCC was established. The expression of Forkhead box P3 (Foxp3), interleukin 10, transforming growth factor-β, chemokine CC motif ligands 17, 20, and CC chemokine receptor 4 was determined using real-time quantitative polymerase chain reaction. Foxp3 expression was also analyzed using immunohistochemistry. The results were compared with those of control mice and of 4NQO-treated mice treated with a cyclooxygenase-2 (COX-2) inhibitor. Well to moderately differentiated tongue SCC was induced in all of the experimental mice. The amount of Tregs of the experimental mice was over 10 times as much as control mice at the early stage of tumor progression. COX-2 inhibitor did not prevent the progression of tongue SCC and did not reduce the total amount of Tregs. Tregs function at the early stage of the development of tongue SCC, and it may be effective to suppress Tregs at the early stage of tumor progression for the treatment and/or prevention of tongue SCC.

Kikuchi-Fujimoto disease: evaluation of prognostic factors and analysis of pathologic findings

CONCLUSION

In Kikuchi-Fujimoto disease (KFD), a low ratio of blastic cells (<70%) in lymph node specimens and absence of atypical lymphocytes in peripheral blood are predictive of a protracted clinical course.

OBJECTIVES

Since KFD is a self-limiting disorder that does not require any specific management, prognostic factors have received little attention. The present study identified clinical and pathological factors that may affect the period from onset to cure of KFD.

METHODS

This retrospective study investigated 43 KFD patients who underwent lymph node biopsy diagnosed by immunohistochemical staining at Okayama University Hospital and Okayama Medical Center from January 2001 to December 2013.

RESULTS

Mean total period from onset to cure was 6 months (median =9.4 months; range =1-37 months). Low ratios of blastic cell proliferation area (<70%) in lymph node specimens (p = 0.011) and absence of atypical lymphocytes in peripheral blood (p = 0.026) were associated with a relatively long duration of KFD.

Soft tissue hematoma of the neck due to thyroid rupture with unusual mechanism

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Massive bleeding from the thyroid without direct neck trauma rarely causes airway compromise.

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Physicians should regard possible thyroid gland rupture in patients with swelling of the neck or acute respiratory failure after direct/indirect trauma to the neck.

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Airway management is the most important consideration in such patients with thyroid injury.

Introduction

Massive bleeding from the thyroid gland causing airway compromise secondary to indirect neck trauma is rare.

Presentation of case

An 89-year-old woman was transferred to our emergency department due to anterior neck pain after a traffic accident. She had been propelled forward and struck her head on the front mirror during emergency braking. Airway patency was confirmed at the first contact. Although her vital signs were stable at presentation, she gradually suffered from respiratory distress and severe dyspnea, implying airway compression, therefore requiring endotracheal intubation. Computed tomography (CT) revealed a large, encapsulated hematoma in the left thyroid gland lobe extending to the upper mediastinum. Contrast-enhanced CT demonstrated an extravasation of the contrast agent around the left superior thyroid artery. The left thyroid artery was ligated and the hematoma was removed immediately. She had a favorable course without further complications and was discharged 36 days after admission.

Discussion

Airway management is the most important consideration in patients with thyroid injury. Treatment should be customized depending on the degree of respiratory distress resulting from of either involvement of the direct airway or secondary compression.

Conclusion

Although hemorrhage from the thyroid gland without blunt trauma is rare, emergency physicians should regard possible thyroid gland rupture in patients with swelling of the neck or acute respiratory failure after direct/indirect trauma to the neck. Observation or operative management for limited or expanding hematoma are appropriately based on fundamental neck trauma principles.

Centrality-Dependent Modification of Jet-Production Rates in Deuteron-Gold Collisions at √[s(NN)]=200 GeV

Jet production rates are measured in p+p and d+Au collisions at sqrt[s_{NN}]=200  GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Jets are reconstructed using the R=0.3 anti-k_{t} algorithm from energy deposits in the electromagnetic calorimeter and charged tracks in multiwire proportional chambers, and the jet transverse momentum (p_{T}) spectra are corrected for the detector response. Spectra are reported for jets with 12<p_{T}<50  GeV/c, within a pseudorapidity acceptance of |η|<0.3. The nuclear-modification factor (R_{dAu}) values for 0%-100% d+Au events are found to be consistent with unity, constraining the role of initial state effects on jet production. However, the centrality-selected R_{dAu} values and central-to-peripheral ratios (R_{CP}) show large, p_{T}-dependent deviations from unity, challenging the conventional models that relate hard-process rates and soft-particle production in collisions involving nuclei.

Single-energy metal artefact reduction with CT for carbon-ion radiation therapy treatment planning

OBJECTIVE

One approach to improving image quality of CT is to use metal artefact reduction image processing, such as single-energy metal artefact reduction (SEMAR). To quantify the impact of image correction on the quality of carbon-ion dose distribution, treatment planning using SEMAR was evaluated.

METHODS

Using a head phantom into which metal screws could be inserted, we acquired standard planning CT images. We calculated dose distributions using phantom images with and without metal added, and with and without SEMAR. Hounsfield unit (HU) and dose distribution variation of these images with and without SEMAR were measured using metal-free image subtraction. We similarly analysed the image data sets of two patients with head and neck cancer who had dental implants.

RESULTS

HU difference between metal-containing images and metal-free images without and with SEMAR were -79.5 ± 97.2 HU and -1.4 ± 19.5 HU on severe artefact area, respectively. The range of dose distribution difference from the prescribed dose between uncorrected and SEMAR-corrected images varied from -19.5% to -3.4% within planning target volume (PTV). PTV-D95 (%) for uncorrected and SEMAR-corrected image data were 82.4% and 95.4%, respectively. For data in patients with metal dental work, PTV-D95 (%) for uncorrected and SEMAR-corrected data were 92.2% and 92.5% (Patient 1), and 90.9% and 95.7% (Patient 2), respectively.

CONCLUSION

SEMAR algorithm shows promise in improving CT image quality and in ensuring an accurate representation of dose distribution.

ADVANCES IN KNOWLEDGE

SEMAR may improve treatment accuracy without the need for dental implant extraction in patients with head and neck cancer.

Diffuse large B-cell lymphoma of the lacrimal sac arising from a patient with IgG4-related disease

A rare case of diffuse large B-cell lymphoma (DLBCL) possibly induced by IgG4-related disease is described. A 78-year-old woman was presented with a mass of the right lacrimal sac that extended to the inferior nasal meatus through the nasolacrimal duct. Pathological diagnosis was DLBCL with diffuse distribution of IgG4 + cells in the background of this lesion. The chronic inflammatory state of IgG4-related disease could have caused the development of DLBCL.

Candidate Resonant Tetraneutron State Populated by the ^{4}He(^{8}He,^{8}Be) Reaction

A candidate resonant tetraneutron state is found in the missing-mass spectrum obtained in the double-charge-exchange reaction ^{4}He(^{8}He,^{8}Be) at 186  MeV/u. The energy of the state is 0.83±0.65(stat)±1.25(syst)  MeV above the threshold of four-neutron decay with a significance level of 4.9σ. Utilizing the large positive Q value of the (^{8}He,^{8}Be) reaction, an almost recoilless condition of the four-neutron system was achieved so as to obtain a weakly interacting four-neutron system efficiently.

Measurements of Elliptic and Triangular Flow in High-Multiplicity 3He+Au Collisions at √(s(NN))=200 GeV

We present the first measurement of elliptic (v(2)) and triangular (v(3)) flow in high-multiplicity (3)He+Au collisions at √(s(NN))=200  GeV. Two-particle correlations, where the particles have a large separation in pseudorapidity, are compared in (3)He+Au and in p+p collisions and indicate that collective effects dominate the second and third Fourier components for the correlations observed in the (3)He+Au system. The collective behavior is quantified in terms of elliptic v(2) and triangular v(3) anisotropy coefficients measured with respect to their corresponding event planes. The v(2) values are comparable to those previously measured in d+Au collisions at the same nucleon-nucleon center-of-mass energy. Comparisons with various theoretical predictions are made, including to models where the hot spots created by the impact of the three (3)He nucleons on the Au nucleus expand hydrodynamically to generate the triangular flow. The agreement of these models with data may indicate the formation of low-viscosity quark-gluon plasma even in these small collision systems.

Validation of a commercial serodiagnostic kit for diagnosing pulmonary Mycobacterium avium complex disease

SETTING

A commercial serodiagnostic kit for diagnosing pulmonary disease due to Mycobacterium avium complex (MAC-PD) was developed and launched in Japan in 2011.

OBJECTIVE

To evaluate the performance of this kit in routine clinical settings.

METHODS

In this retrospective single-centre study, data on serum levels of anti-glycopeptidolipid (GPL) core IgA antibody (U/ml) measured using the kit were analysed in patients diagnosed with MAC-PD according to American Thoracic Society criteria, in those with pulmonary tuberculosis (PTB) or pulmonary M. kansasii disease and in healthy volunteers.

RESULTS

The anti-GPL-core IgA antibody levels of serum were significantly higher (P < 0.0001) in patients with MAC-PD (n = 485) than in those with PTB (n = 133) or pulmonary M. kansasii disease (n = 23) or in healthy subjects (n = 265). When the cut-off level was set at 0.7 U/ml, the sensitivity and specificity were respectively 78.6% and 96.9%. Higher antibody levels were observed in patients with greater extent of disease on chest computed tomography (P < 0.0001).

CONCLUSIONS

The serodiagnostic kit revealed good sensitivity and specificity. The antibody levels may reflect disease activity. Additional work is needed to determine whether the diagnostic assay could be used in conjunction with current diagnostic criteria to improve the diagnosis of MAC-PD.

Development of fast patient position verification software using 2D-3D image registration and its clinical experience

To improve treatment workflow, we developed a graphic processing unit (GPU)-based patient positional verification software application and integrated it into carbon-ion scanning beam treatment. Here, we evaluated the basic performance of the software. The algorithm provides 2D/3D registration matching using CT and orthogonal X-ray flat panel detector (FPD) images. The participants were 53 patients with tumors of the head and neck, prostate or lung receiving carbon-ion beam treatment. 2D/3D-ITchi-Gime (ITG) calculation accuracy was evaluated in terms of computation time and registration accuracy. Registration calculation was determined using the similarity measurement metrics gradient difference (GD), normalized mutual information (NMI), zero-mean normalized cross-correlation (ZNCC), and their combination. Registration accuracy was dependent on the particular metric used. Representative examples were determined to have target registration error (TRE) = 0.45 ± 0.23 mm and angular error (AE) = 0.35 ± 0.18° with ZNCC + GD for a head and neck tumor; TRE = 0.12 ± 0.07 mm and AE = 0.16 ± 0.07° with ZNCC for a pelvic tumor; and TRE = 1.19 ± 0.78 mm and AE = 0.83 ± 0.61° with ZNCC for lung tumor. Calculation time was less than 7.26 s.The new registration software has been successfully installed and implemented in our treatment process. We expect that it will improve both treatment workflow and treatment accuracy.

Significance of Development and Reversion of Collaterals on MRI in Early Neurologic Improvement and Long-Term Functional Outcome after Intravenous Thrombolysis for Ischemic Stroke

BACKGROUND AND PURPOSE

Predicting response to rtPA is essential in the era of endovascular therapy for stroke. The purpose of this study was to elucidate prognostic factors of early neurologic improvement and long-term outcome with respect to the development and reversion of leptomeningeal collaterals in recanalization therapy after acute ischemic stroke.

MATERIALS AND METHODS

We analyzed consecutive patients with proximal MCA occlusion treated with rtPA from 2007 to 2012 at 2 hospital stroke centers. All patients routinely underwent brain MR imaging before rtPA. To assess the reversion of collateral signs, we included patients who underwent follow-up MR imaging. We assessed the development and reversion of collaterals by using a combination of 2 MR imaging collateral markers, the hyperintense vessel sign and the posterior cerebral artery laterality sign. Early neurologic improvement was defined as a decrease in the NIHSS score of ≥10 or a score of ≤2 at 24 hours of treatment.

RESULTS

Early neurologic improvement was observed in 22 of 48 eligible patients. The development of collaterals at arrival (15/22 versus 9/26, P = .042) was significantly associated with early neurologic improvement. Multivariate analysis adjusting for other variables showed that the development of collaterals at arrival (OR, 4.82; 95% CI, 1.34-19.98; P = .015) was independently associated with early neurologic improvement. Reversion of collaterals was significantly associated with successful recanalization (P < .001), and multivariate analysis showed that the reversion of collaterals was an independent prognostic factor of long-term functional outcome (OR, 5.07; 95% CI, 1.38-22.09; P = .013).

CONCLUSIONS

Our results indicate that the development of leptomeningeal collaterals plays a crucial role in achieving early neurologic improvement, and reversion of collaterals predicts a favorable outcome via arterial recanalization after rtPA treatment for acute stroke.

How long should we continue S-1 as adjuvant chemotherapy for squamous cell carcinoma of the head and neck?

CONCLUSION

It appears that patients with SCCHN should be recommended to take S-1 for more than 1 year and, if possible, more than 2 years, as adjuvant chemotherapy for SCCHN.

OBJECTIVES

There is no established consensus on the duration of administration of S-1 as adjuvant chemotherapy for squamous cell carcinoma of the head and neck (SCCHN). Since it might be difficult to undergo prospective randomized study to identify the optimal duration of the administration period of S-1 without a standard, the authors have undergone a retrospective clinical study to decide the tentative standard of therapeutic duration of S-1 as adjuvant chemotherapy for SCCHN.

METHODS

The clinical records of 89 patients with SCCHN who underwent adjuvant chemotherapy with S-1 were investigated.

RESULTS

The median duration of S-1 administration as adjuvant chemotherapy for SCCHN was 7 months (range = 0.1-58 months). Disease-free survivals (DFSs) were generally longer when S-1 administration periods were longer. After adjusting for prognostic factors, S-1 administration periods of 24 months or longer showed significantly lower hazard ratios (HRs) than 0-12 months.

Measurement of Long-Range Angular Correlation and Quadrupole Anisotropy of Pions and (Anti)Protons in Central d+Au Collisions at sqrt[s_{NN}]=200 GeV

We present azimuthal angular correlations between charged hadrons and energy deposited in calorimeter towers in central d+Au and minimum bias p+p collisions at sqrt[s_{NN}]=200 GeV. The charged hadron is measured at midrapidity |η|<0.35, and the energy is measured at large rapidity (-3.7<η<-3.1, Au-going direction). An enhanced near-side angular correlation across |Δη|>2.75 is observed in d+Au collisions. Using the event plane method applied to the Au-going energy distribution, we extract the anisotropy strength v_{2} for inclusive charged hadrons at midrapidity up to p_{T}=4.5 GeV/c. We also present the measurement of v_{2} for identified π^{±} and (anti)protons in central d+Au collisions, and observe a mass-ordering pattern similar to that seen in heavy-ion collisions. These results are compared with viscous hydrodynamic calculations and measurements from p+Pb at sqrt[s_{NN}]=5.02 TeV. The magnitude of the mass ordering in d+Au is found to be smaller than that in p+Pb collisions, which may indicate smaller radial flow in lower energy d+Au collisions.

Variation in patient position and impact on carbon-ion scanning beam distribution during prostate treatment

OBJECTIVE

We assessed the impact of changes in patient position on carbon-ion scanning beam distribution during treatment for prostate cancer.

METHODS

68 patients were selected. Carbon-ion scanning dose was calculated. Two different planning target volumes (PTVs) were defined: PTV1 was the clinical target volume plus a set-up margin for the anterior/lateral sides and posterior side, while PTV2 was the same as PTV1 minus the posterior side. Total prescribed doses of 34.4 Gy [relative biological effectiveness (RBE)] and 17.2 Gy (RBE) were given to PTV1 and PTV2, respectively. To estimate the influence of geometric variations on dose distribution, the dose was recalculated on the rigidly shifted single planning CT based on two dimensional-three dimensional rigid registration of the orthogonal radiographs before and after treatment for the fraction of maximum positional changes.

RESULTS

Intrafractional patient positional change values averaged over all patients throughout the treatment course were less than the target registration error = 2.00 mm and angular error = 1.27°. However, these maximum positional errors did not occur in all 12 treatment fractions. Even though large positional changes occurred during irradiation in all treatment fractions, lowest dose encompassing 95% of the target (D95)-PTV1 was >98% of the prescribed dose.

CONCLUSION

Intrafractional patient positional changes occurred during treatment beam irradiation and degraded carbon-ion beam dose distribution. Our evaluation did not consider non-rigid deformations, however, dose distribution was still within clinically acceptable levels.

ADVANCES IN KNOWLEDGE

Inter- and intrafractional changes did not affect carbon-ion beam prostate treatment accuracy.

Digital reconstructed radiography with multiple color image overlay for image-guided radiotherapy

Registration of patient anatomical structures to the reference position is a basic part of the patient set-up procedure. Registration of anatomical structures between the site of beam entrance on the patient surface and the distal target position is particularly important. Here, to improve patient positional accuracy during set-up for particle beam treatment, we propose a new visualization methodology using digitally reconstructed radiographs (DRRs), overlaid DRRs, and evaluation of overlaid DRR images in clinical cases. The overlaid method overlays two DRR images in different colors by dividing the CT image into two CT sections at the distal edge of the target along the treatment beam direction. Since our hospital uses fixed beam ports, the treatment beam angles for this study were set at 0 and 90 degrees. The DRR calculation direction was from the X-ray tube to the imaging device, and set to 180/270 degrees and 135/225 degrees, based on the installation of our X-ray imaging system. Original and overlaid DRRs were calculated using CT data for two patients, one with a parotid gland tumor and the other with prostate cancer. The original and overlaid DRR images were compared. Since the overlaid DRR image was completely separated into two regions when the DRR calculation angle was the same as the treatment beam angle, the overlaid DRR visualization technique was able to provide rich information for aiding recognition of the relationship between anatomical structures and the target position. This method will also be useful in patient set-up procedures for fixed irradiation ports.

Implementation of a target volume design function for intrafractional range variation in a particle beam treatment planning system

OBJECTIVE

Treatment planning for charged particle therapy in the thoracic and abdominal regions should take account of range uncertainty due to intrafractional motion. Here, we developed a design tool (4Dtool) for the target volume [field-specific target volume (FTV)], which accounts for this uncertainty using four-dimensional CT (4DCT).

METHODS

Target and normal tissue contours were input manually into a treatment planning system (TPS). These data were transferred to the 4Dtool via the picture archiving and communication system (PACS). Contours at the reference phase were propagated to other phases by deformable image registration. FTV was calculated using 4DCT on the 4Dtool. The TPS displays FTV contours using digital imaging and communications in medicine files imported from the PACS. These treatment parameters on the CT image at the reference phase were then used for dose calculation on the TPS. The tool was tested in single clinical case randomly selected from patients treated at our centre for lung cancer.

RESULTS

In this clinical case, calculation of dose distribution with the 4Dtool resulted in the successful delivery of carbon-ion beam at the reference phase of 95% of the prescribed dose to the clinical target volume (CTV). Application to the other phases also provided sufficient dose to the CTV.

CONCLUSION

The 4Dtool software allows the design of the target volume with consideration to intrafractional range variation and is now in routine clinical use at our institution.

ADVANCES IN KNOWLEDGE

Our alternative technique represents a practical approach to four-dimensional treatment planning within the current state of charged particle therapy.