Three-dimensional cluster formation and structure in heterogeneous dose distribution of intensity modulated radiation therapy

Publication date: Available online 30 March 2018
Source:Radiotherapy and Oncology
Author(s): Ming Chao, Jie Wei, Ganesh Narayanasamy, Yading Yuan, Yeh-Chi Lo, José A. Peñagarícano
PurposeTo investigate three-dimensional cluster structure and its correlation to clinical endpoint in heterogeneous dose distributions from intensity modulated radiation therapy.MethodsTwenty-five clinical plans from twenty-one head and neck (HN) patients were used for a phenomenological study of the cluster structure formed from the dose distributions of organs at risks (OARs) close to the planning target volumes (PTVs). Initially, OAR clusters were searched to examine the pattern consistence among ten HN patients and five clinically similar plans from another HN patient. Second, clusters of the esophagus from another ten HN patients were scrutinized to correlate their sizes to radiobiological parameters. Finally, an extensive Monte Carlo (MC) procedure was implemented to gain deeper insights into the behavioral properties of the cluster formation.ResultsClinical studies showed that OAR clusters had drastic differences despite similar PTV coverage among different patients, and the radiobiological parameters failed to positively correlate with the cluster sizes. MC study demonstrated the inverse relationship between the cluster size and the cluster connectivity, and the nonlinear changes in cluster size with dose thresholds. In addition, the clusters were insensitive to the shape of OARs.ConclusionThe results demonstrated that the cluster size could serve as an insightful index of normal tissue damage. The clinical outcome of the same dose–volume might be potentially different.



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Correction to: Dynamic susceptibility contrast (DSC) perfusion MRI in differential diagnosis between radionecrosis and neoangiogenesis in cerebral metastases using rCBV, rCBF and K2

Abstract

In the original publication of the article, the name of the last author was incorrect. The correct name should read as given below:

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Three-dimensional cluster formation and structure in heterogeneous dose distribution of intensity modulated radiation therapy

To investigate three-dimensional cluster structure and its correlation to clinical endpoint in heterogeneous dose distributions from intensity modulated radiation therapy.

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Fast 5DOF needle tracking in iOCT

Abstract

Purpose

Intraoperative optical coherence tomography (iOCT) is an increasingly available imaging technique for ophthalmic microsurgery that provides high-resolution cross-sectional information of the surgical scene. We propose to build on its desirable qualities and present a method for tracking the orientation and location of a surgical needle. Thereby, we enable the direct analysis of instrument–tissue interaction directly in OCT space without complex multimodal calibration that would be required with traditional instrument tracking methods.

Method

The intersection of the needle with the iOCT scan is detected by a peculiar multistep ellipse fitting that takes advantage of the directionality of the modality. The geometric modeling allows us to use the ellipse parameters and provide them into a latency-aware estimator to infer the 5DOF pose during needle movement.

Results

Experiments on phantom data and ex vivo porcine eyes indicate that the algorithm retains angular precision especially during lateral needle movement and provides a more robust and consistent estimation than baseline methods.

Conclusion

Using solely cross-sectional iOCT information, we are able to successfully and robustly estimate a 5DOF pose of the instrument in less than 5.4 ms on a CPU.

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A rare case of atypical thoracodorsal artery: a challenge for flap reconstruction.

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A rare case of atypical thoracodorsal artery: a challenge for flap reconstruction.

Surg Radiol Anat. 2018 Mar 29;:

Authors: Kumar N, Aithal AP, Nayak SB, Bhaskar R

Abstract
The thoracodorsal artery mainly supplies the latissimus dorsi muscle. Anatomical details pertaining to the origin and distribution of thoracodorsal artery are important because the latissimus dorsi myocutaneous flap is one of the most reliable and versatile flaps used in reconstructive surgery. Atypical origin and course of the thoracodorsal artery is, therefore, a challenge for flap reconstruction surgeries. In the present case, we report multiple variations in the branching pattern of axillary artery. The thoracodorsal artery had an unusual origin from the second part of axillary artery. The trunk of thoracoacromial artery was absent. The thoracodorsal artery after its origin, descended downwards over the lateral pectoral region lying deep to pectoralis minor but superficial to teres major muscles. It terminated by supplying the latissimus dorsi muscle. Due to the presence of atypical thoracodorsal branch, the subscapular artery continued as the circumflex scapular artery.

PMID: 29594336 [PubMed - as supplied by publisher]

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The retromolar canals and foramina: radiographic observation and application to oral surgery.

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The retromolar canals and foramina: radiographic observation and application to oral surgery.

Surg Radiol Anat. 2018 Mar 29;:

Authors: Kikuta S, Iwanaga J, Nakamura K, Hino K, Nakamura M, Kusukawa J

Abstract
PURPOSE: The retromolar canal (RMC) and foramen (RMF) are anatomic variants in the retromolar area of the mandible. The purpose of this study was to clarify the relationship between the RMC and RMF and related complications, and to reveal how the RMC could impact the mandibular anatomy using cone-beam computed tomography (CBCT) and panoramic images (PAN).
MATERIALS AND METHODS: CBCT and PAN images of 50 patients were retrospectively analyzed to investigate the morphology of the RMC and RMF, and their impact on impacted third molar surgery and orthognathic surgery.
RESULTS: In PAN images, neither the RMC nor RMF was detected. In CBCT images, the RMCs were detected in 26% (13/50) of the patients. A double RMC was detected on one side of one patient. The diameter of the RMC ranged from 0.8 to 2.9 mm (mean; 1.5 ± 0.6 mm), and the RMF ranged from 0.6 to 2.3 mm (mean; 1.1 ± 0.5 mm). No patients experienced unexpected bleeding. Unilateral postoperative hypoesthesia of the buccal gingiva in the molar region was reported in 6.7% of patients with the RMC.
CONCLUSIONS: Hypoesthesia of the buccal gingiva in the lower molar region may be the main complication when the RMC is damaged.

PMID: 29594335 [PubMed - as supplied by publisher]

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Uncertainty in positioning ion chamber at reference depth for various water phantoms

Publication date: May–June 2018
Source:Reports of Practical Oncology & Radiotherapy, Volume 23, Issue 3
Author(s): Naoki Kinoshita, Hiroshi Oguchi, Toshiki Adachi, Hiroki Shioura, Hirohiko Kimura
BackgroundUncertainty in the calibration of high-energy radiation sources is dependent on user and equipment type.AimWe evaluated the uncertainty in the positioning of a cylindrical chamber at a reference depth for reference dosimetry of high-energy photon beams and the resulting uncertainty in the chamber readings for 6- and 10-MV photon beams. The aim was to investigate major contributions to the positioning uncertainty to reduce the uncertainty in calibration for external photon beam radiotherapy.Materials and methodsThe following phantoms were used: DoseView 1D, WP1D, 1D SCANNER, and QWP-07 as one-dimensional (1D) phantoms for a vertical-beam geometry; GRI-7632 as a phantom for a fixed waterproofing sleeve; and PTW type 41023 and QWP-04 as 1D phantoms for a horizontal-beam geometry. The uncertainties were analyzed as per the Guide to the Expression of Uncertainty in Measurement.ResultsThe positioning and resultant uncertainties in chamber readings ranged from 0.22 to 0.35mm and 0.12–0.25%, respectively, among the phantoms (using a coverage factor k=1 in both cases). The major contributions to positioning uncertainty are: definition of the origin for phantoms among users for the 1D phantoms for a vertical-beam geometry, water level adjustment among users for the phantom for a fixed waterproofing sleeve, phantom window deformation, and non-water material of the window for the 1D phantoms for a horizontal-beam geometry.ConclusionThe positioning and resultant uncertainties in chamber readings exhibited minor differences among the seven phantoms. The major components of these uncertainties differed among the phantom types investigated.



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Dual addressing of thymidine synthesis pathways for effective targeting of proliferating melanoma.

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Dual addressing of thymidine synthesis pathways for effective targeting of proliferating melanoma.

Cancer Med. 2017 Jul;6(7):1639-1651

Authors: Miran T, Vogg ATJ, El Moussaoui L, Kaiser HJ, Drude N, von Felbert V, Mottaghy FM, Morgenroth A

Abstract
Here, we examined the potential of blocking the thymidine de novo synthesis pathways for sensitizing melanoma cells to the nucleoside salvage pathway targeting endogenous DNA irradiation. Expression of key nucleotide synthesis and proliferation enzymes thymidylate synthase (TS) and thymidine kinase 1 (TK1) was evaluated in differentiated (MITFhigh [microphthalmia-associated transcription factor] IGR1) and invasive (MITFmedium IGR37) melanoma cells. For inhibition of de novo pathways cells were incubated either with an irreversible TS inhibitor 5-fluoro-2'-deoxyuridine (FdUrd) or with a competitive dihydrofolate-reductase (DHFR) inhibitor methotrexate (MTX). Salvage pathway was addressed by irradiation-emitting thymidine analog [123/125 I]-5-iodo-4'-thio-2'-deoxyuridine (123/125 I-ITdU). The in vivo targeting efficiency was visualized by single-photon emission computed tomography. Pretreatment with FdUrd strongly increased the cellular uptake and the DNA incorporation of 125 I-ITdU into the mitotically active IGR37 cells. This effect was less pronounced in the differentiated IGR1 cells. In vivo, inhibition of TS led to a high and preferential accumulation of 123 I-ITdU in tumor tissue. This preclinical study presents profound rationale for development of therapeutic approach by highly efficient and selective radioactive targeting one of the crucial salvage pathways in melanomas.

PMID: 28608446 [PubMed - indexed for MEDLINE]

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Correction to: Global and Japanese regional variations in radiologist potential workload for computed tomography and magnetic resonance imaging examinations

Abstract

In Results of Abstract, the first sentence should read as: The radiologist potential workload in Japan was 2.78–4.17 times higher than those in other countries.

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LV function validation of computer-assisted interventional system for cardiac resyncronisation therapy

Abstract

Purpose

Cardiac resynchronisation therapy (CRT) is an established treatment for symptomatic patients with heart failure, a prolonged QRS duration, and impaired left ventricular (LV) function; however, non-response rates remain high. Recently proposed computer-assisted interventional platforms for CRT provide new routes to improving outcomes. Interventional systems must process information in an accurate, fast and highly automated way that is easy for the interventional cardiologists to use. In this paper, an interventional CRT platform is validated against two offline diagnostic tools to demonstrate that accurate information processing is possible in the time critical interventional setting.

Methods

The study consisted of 3 healthy volunteers and 16 patients with heart failure and conventional criteria for CRT. Data analysis included the calculation of end-diastolic volume, end-systolic volume, stroke volume and ejection fraction; computation of global volume over the cardiac cycle as well as time to maximal contraction expressed as a percentage of the total cardiac cycle.

Results

The results showed excellent correlation ( \(R^{2}\) values of \(>\,0.99\) and Pearson correlation coefficient of \(>\,0.98\) ) with comparable offline diagnostic tools.

Conclusion

Results confirm that our interventional system has good accuracy in everyday clinical practice and can be of clinical utility in identification of CRT responders and LV function assessment.

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Vital Signs in Radiologic Education

Publication date: Available online 29 March 2018
Source:Academic Radiology
Author(s): Priscilla J. Slanetz




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A Feasibility Study of Single-inhalation, Single-energy Xenon-enhanced CT for High-resolution Imaging of Regional Lung Ventilation in Humans

Publication date: Available online 29 March 2018
Source:Academic Radiology
Author(s): Daniel W. Pinkham, Mohammadreza Negahdar, Tokihiro Yamamoto, Erik Mittra, Maximilian Diehn, Viswam S. Nair, Paul J. Keall, Peter G. Maxim, Billy W. Loo
Rationale and ObjectivesThe objective of this study was to assess the feasibility of single-inhalation xenon-enhanced computed tomography (XeCT) to provide clinically practical, high-resolution pulmonary ventilation imaging to clinics with access to only a single-energy computed tomography scanner, and to reduce the subject's overall exposure to xenon by utilizing a higher (70%) concentration for a much shorter time than has been employed in prior studies.Materials and MethodsWe conducted an institutional review board-approved prospective feasibility study of XeCT for 15 patients undergoing thoracic radiotherapy. For XeCT, we acquired two breath-hold single-energy computed tomography images of the entire lung with a single inhalation each of 100% oxygen and a mixture of 70% xenon and 30% oxygen, respectively. A video biofeedback system for coached patient breathing was used to achieve reproducible breath holds. We assessed the technical success of XeCT acquisition and side effects. We then used deformable image registration to align the breath-hold images with each other to accurately subtract them, producing a map of lung xenon distribution. Additionally, we acquired ventilation single-photon emission computed tomography-computed tomography (V-SPECT-CT) images for 11 of the 15 patients. For a comparative analysis, we partitioned each lung into 12 sectors, calculated the xenon concentration from the Hounsfield unit enhancement in each sector, and then correlated this with the corresponding V-SPECT-CT counts.ResultsXeCT scans were tolerated well overall, with a mild (grade 1) dizziness as the only side effect in 5 of the 15 patients. Technical failures in five patients occurred because of inaccurate breathing synchronization with xenon gas delivery, leaving seven patients analyzable for XeCT and single-photon emission computed tomography correlation. Sector-wise correlations were strong (Spearman coefficient >0.75, Pearson coefficient >0.65, P value <.002) for two patients for whom ventilation deficits were visibly pronounced in both scans. Correlations were nonsignificant for the remaining five who had more homogeneous XeCT ventilation maps, as well as strong V-SPECT-CT imaging artifacts attributable to airway deposition of the aerosolized imaging agent. Qualitatively, XeCT demonstrated higher resolution and no central airway deposition artifacts compared to V-SPECT-CT.ConclusionsIn this pilot study, single-breath XeCT ventilation imaging was generally feasible for patients undergoing thoracic radiotherapy, using an imaging protocol that is clinically practical and potentially widely available. In the future, the xenon delivery failures can be addressed by straightforward technical improvements to the patient biofeedback coaching system.



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