Yield of TB screening in prisons in Tajikistan.

Background: The rate of TB in prison institutions is estimated to be 23 times higher than in the general population. Limited documentation exists regarding TB screening in Tajikistan's prisons. This study aims to report findings from a TB screening conducted in prison facilities in Tajikistan.

Household drug-resistant TB contact tracing in Tajikistan.

Tajikistan has a high burden of rifampicin-resistant TB (RR-TB), with 2,700 new cases estimated for 2021 (28/100,000 population). TB is spread among household members through close interaction and children exposed through household contact progress to disease rapidly and frequently. We retrospectively analysed programmatic data from household contact tracing in Dushanbe over 50 months.

A pandemic within a pandemic? Admission to COVID-19 wards in hospitals is associated with increased prevalence of antimicrobial resistance in two African settings.

Background: Patients who develop severe illness due to COVID-19 are more likely to be admitted to hospital and acquire bacterial co-infections, therefore the WHO recommends empiric treatment with antibiotics. Few reports have addressed the impact of COVID-19 management on emergence of nosocomial antimicrobial resistance (AMR) in resource constrained settings. This study aimed to ascertain whether being admitted to a COVID-19 ward (with COVID-19 infection) compared to a non-COVID-19 ward (as a COVID-19 negative patient) was associated with a change in the prevalence of bacterial hospital acquired infection (HAI) species or resistance patterns, and whether there were differences in antimicrobial stewardship (AMS) and infection prevention and control (IPC) guidelines between COVID-19 and non-COVID-19 wards.

Gaps and opportunities in the climate change, migration and health nexus: Insights from a questionnaire based study of practitioners and researchers.

Background: : While climate change and migration are separately recognised as public health challenges, the combination of the two - climate change-induced migration which is predicted to increase through this century - requires further research to ensure population health needs are met. As such, this paper aims to identify initial gaps and opportunities in the nexus of climate change, migration and health research.

Methods: : We conducted a questionnaire based study of academics and practitioners working in the fields of climate change, migration and health.

Estimating the excess lifetime risk of radiation induced secondary malignancy (SMN) in pediatric patients treated with craniospinal irradiation (CSI): Conventional radiation therapy versus helical intensity modulated radiation therapy.

Purpose: To quantify the risk of radiation-induced second malignancies (SMN) in pediatric patients receiving craniospinal irradiation (CSI) either with 3-dimensional conformal radiation therapy (Conv CSI) or tomotherapy helical intensity modulated radiation therapy (Tomo CSI).

Methods And Materials: A novel predictive model that accounts for short- and long-term carcinogenesis was incorporated into our institutional treatment planning system to quantify the lifetime risk of SMN in incidentally irradiated organs. Five pediatric patients previously treated with CSI were studied.

Technical Note: Fabricating Cerrobend grids with 3D printing for spatially modulated radiation therapy: A feasibility study.

Purpose: Grid therapy has promising applications in the radiation treatment of large tumors. However, research and applications of grid therapy are limited by the accessibility of the specialized blocks that produce the grid of pencil-like radiation beams. In this study, a Cerrobend grid block was fabricated using the 3D printing technique.

Dosimetric effect due to the motion during deep inspiration breath hold for left-sided breast cancer radiotherapy.

Deep inspiration breath-hold (DIBH) radiotherapy for left-sided breast cancer can reduce cardiac exposure and internal motion. We modified our in-house treatment planning system (TPS) to retrospectively analyze breath-hold motion log files to calculate the dosimetric effect of the motion during breath hold. Thirty left-sided supine DIBH breast patients treated using AlignRT were studied.

Direct aperture optimization using an inverse form of back-projection.

Direct aperture optimization (DAO) has been used to produce high dosimetric quality intensity-modulated radiotherapy (IMRT) treatment plans with fast treatment delivery by directly modeling the multileaf collimator segment shapes and weights. To improve plan quality and reduce treatment time for our in-house treatment planning system, we implemented a new DAO approach without using a global objective function (GFO). An index concept is introduced as an inverse form of back-projection used in the CT multiplicative algebraic reconstruction technique (MART).

Comparison of User-Directed and Automatic Mapping of the Planned Isocenter to Treatment Space for Prostate IGRT.

Image-guided radiotherapy (IGRT), adaptive radiotherapy (ART), and online reoptimization rely on accurate mapping of the radiation beam isocenter(s) from planning to treatment space. This mapping involves rigid and/or nonrigid registration of planning (pCT) and intratreatment (tCT) CT images. The purpose of this study was to retrospectively compare a fully automatic approach, including a non-rigid step, against a user-directed rigid method implemented in a clinical IGRT protocol for prostate cancer.

SU-E-T-623: Utilizing a Hybrid Optimizer to Improve Dose Conformity during IMRT Planning.

Purpose: For IMRT treatment planning, an index-dose based algorithm features a fast approach in optimizing beam shapes and weights, and the quasi-Newton method is adopted in segment weight optimization by many commercial products. By combining these two optimizers, we aim to improve IMRT plan quality by achieving better normal tissue sparing.

Methods: An IMRT plan was generated using an in-house treatment planning system in three steps: 1) optimize fluence using beamlet intensity modulation, 2) generate Multi-collimator leaf sequence and segment weights, 3) tune the segment shapes and weights as each segment treated as a single beam.

Is image registration of fluorodeoxyglucose-positron emission tomography/computed tomography for head-and-neck cancer treatment planning necessary?

Purpose: To evaluate dosimetry and patterns of failure related to fluorodeoxyglucose-positron emission tomography (FDG-PET)-defined biological tumor volumes (BTVs) for head-and-neck squamous cell carcinoma (HNSCC) treated with definitive radiotherapy (RT).

Methods And Materials: We conducted a retrospective study of 91 HNSCC patients who received pretreatment PET/CT scans that were not formally used for target delineation. The median follow-up was 34.

Improving quality of patient care by improving daily practice in radiation oncology.

Radiation oncology is an ever-advancing, complex, technologically based specialty that has been thrust into the public spotlight because of recent reports of serious treatment delivery errors that have impacted the quality of patient care. Although quality assurance (QA) initiatives are already common place in radiation oncology, the continued complex technology and automation-based advances in radiotherapy have created new safety challenges. The ongoing evolution of safety challenges in radiation oncology requires corresponding evolution in workflow and QA programs to ensure the quality of patient care.

Compensators: an alternative IMRT delivery technique.

Seven years of experience in compensator intensity-modulated radiotherapy (IMRT) clinical implementation are presented. An inverse planning dose optimization algorithm was used to generate intensity modulation maps, which were delivered via either the compensator or segmental multileaf collimator (MLC) IMRT techniques. The in-house developed compensator-IMRT technique is presented with the focus on several design issues.

Beam orientation selection for intensity-modulated radiation therapy based on target equivalent uniform dose maximization.

Purpose: To develop an automated beam-orientation selection procedure for intensity-modulated radiotherapy (IMRT), and to determine if a small number of beams picked by this automated procedure can yield results comparable to a large number of manually placed orientations.

Methods And Materials: The automated beam selection procedure maximizes an unconstrained objective function composed of target equivalent uniform dose (EUD) and critical structure dose-volume histogram (DVH) constraints. Beam orientations are selected from a large feasible set of directions through a series of alternating fluence optimization and orientation alteration steps, until convergence to a stable orientation set.

Dose optimization via index-dose gradient minimization.

This paper presents an iterative optimization algorithm based on gradient minimization of index dose, defined as the product of physical dose and a numerical index. Acting as a template the index distribution is designed to represent the dosimetry that meets the dose volume histogram-based optimization objectives. The treatment dosimetry is optimized when the uniformity of the index-dose distribution is maximized.

A quality and efficiency analysis of the IMFAST segmentation algorithm in head and neck "step & shoot" IMRT treatments.

The performance of segmentation algorithms used in IMFAST for "step & shoot" IMRT treatment delivery is evaluated for three head and neck clinical treatments of different optimization objectives. The segmentation uses the intensity maps generated by the in-house TPS PLANUNC using the index-dose minimization algorithm. The dose optimization objectives include PTV dose uniformity and dose volume histogram-specified critical structure sparing.

Intensity modulation delivery techniques: "step & shoot" MLC auto-sequence versus the use of a modulator.

Two intensity modulation radiotherapy (IMRT) delivery systems, the "step & shoot" multileaf collimator (MLC) auto-sequence and the use of an intensity modulator, are compared with emphasis on the dose optimization quality and the treatment irradiation time. The intensity modulation (IM) was created by a dose gradient optimization algorithm which maximizes the target dose uniformity while maintaining dose to critical structures below a set tolerance defined by the user in terms of either a single dose value or a dose volume histogram curve for each critical structure. Two clinical cases were studied with and without dose optimization: a three-field sinus treatment and a six-field nasopharyngeal treatment.

A comparison of different intensity modulation treatment techniques for tangential breast irradiation.

Purpose: Several intensity modulation (IM) treatment techniques for tangential breast irradiation were evaluated in terms of dose uniformity in the treated breast volume, contralateral breast dose, and treatment irradiation time.

Methods And Materials: Contralateral breast dose was measured via TLD chips, and the dose uniformity was calculated on two anthropomorphic phantoms. IM was applied to all beams or to the lateral-medial (LM) beam only.

Image registration: an essential part of radiation therapy treatment planning.

Purpose: We believe that a three-dimensional (3D) registration of nonplanning (diagnostic) imaging data with the planning computed tomography (CT) offers a substantial improvement in tumor target identification for many radiation therapy patients. The purpose of this article is to review and discuss our experience to date.

Methods And Materials: We reviewed the charts and treatment planning records of all patients that underwent 3D radiation treatment planning in our department from June 1994 to December 1995, to learn which patients had image registration performed and why it was thought they would benefit from this approach.

Three-dimensional visualization and image processing in the evaluation of patterned injuries. The AFIP/UNC experience in the Rodney King case.

We used image processing to elucidate patterned injuries in a case of assault with a police baton. Three-dimensional visualization techniques were then used to correlate the location of patterned injuries with subjacent fracture and soft tissue damage. The visualization methods are discussed.

Benchmark test cases for evaluation of computer-based methods for detection of setup errors: realistic digitally reconstructed electronic portal images with known setup errors.

Purpose: The purpose of this investigation was to develop methods and software for computing realistic digitally reconstructed electronic portal images with known setup errors for use as benchmark test cases for evaluation and intercomparison of computer-based methods for image matching and detecting setup errors in electronic portal images.

Methods And Materials: An existing software tool for computing digitally reconstructed radiographs was modified to compute simulated megavoltage images. An interface was added to allow the user to specify which setup parameter(s) will contain computer-induced random and systematic errors in a reference beam created during virtual simulation.

Improving treatment planning accuracy through multimodality imaging.

Purpose: In clinical practice, physicians are constantly comparing multiple images taken at various times during the patient's treatment course. One goal of such a comparison is to accurately define the gross tumor volume (GTV). The introduction of three-dimensional treatment planning has greatly enhanced the ability to define the GTV, but there are times when the GTV is not visible on the treatment-planning computed tomography (CT) scan.

A portable software tool for computing digitally reconstructed radiographs.

Purpose: To develop a portable software tool for fast computation of digitally reconstructed radiographs (DRR) with a friendly user interface and versatile image format and display options. To provide a means for interfacing with commercial and custom three-dimensional (3D) treatment planning systems. To make the tool freely available to the Radiation Oncology community.

Three-dimensional reconstruction of a bullet path: validation by computed radiography.

Three-dimensional visualization is an important tool in the evaluation and demonstration of injury. Creating convincing graphics, however, requires strict distinction between illustrative and reconstructive visualizations and a method of validation. We present a case in which we used a radiation-planning tool to provide a 3-dimensional illustrative visualization of a contact gunshot wound to the head, and validated the result by comparing computed radiographs with radiographs taken at autopsy.

The tetrad and hexad: maximum beam separation as a starting point for noncoplanar 3D treatment planning: prostate cancer as a test case.

Purpose: In contrast to computer optimized three-dimensional (3D) treatment planning, we have used maximally separated, noncoplanar beams as the starting point for 3D treatment planning of prostate cancer to maximize the rate of dose fall off from the target volume and minimize dose to surrounding tissues.

Materials And Methods: A planar four-field plan, a planar six-field plan, a tetrad plan, and a hexad plan are analyzed using a 3D treatment planning system which is capable of displaying real-time 3D dose distributions within volume reconstructed data sets (VISTAnet--an extension of the virtual simulator). The tetrad plan is based on the methane molecule and the hexad plan has a minimum separation of 58 degrees on beam entrance.