Effect of dental metal artifact conversion volume on dose distribution in head‐and‐neck volumetric‐modulated arc therapy

Purpose: During treatment planning for head‐and‐neck volumetric‐modulated arc therapy (VMAT), manual contouring of the metal artifact area of artificial teeth is done, and the area is replaced with water computed tomography (CT) values for dose calculation. This contouring of the metal artifact areas, which is performed manually, is subject to human variability. The purpose of this study is to evaluate and analyze the effect of inter‐observer variation on dose distribution. Methods: The subjects were 25 cases of cancer of the oropharynx for which VMAT was performed. Six radiation oncologists (ROs) performed metal artifact contouring for all of the cases. Gross tumor volume, clinical target volume, planning target volume (PTV), and oral cavity were evaluated. The contouring of the six ROs was divided into two groups, small and large groups. A reference RO was determined for each group and the dose distribution was compared with those of the other radiation oncologists by gamma analysis (GA). As an additional experiment, we changed the contouring of each dental metal artifact area, creating enlarged contours (L), reduced contours (S), and undrawn contours (N) based on the contouring by the six ROs and compared these structure sets. Results: The evaluation of inter‐observer variation showed no significant difference between the large and small groups, and the GA pass rate was 100%. Similar results were obtained comparing structure sets L and S, but in the comparison of structure sets L and N, there were cases with pass rates below 70%. Conclusions: The results show that the artificial variability of manual artificial tooth metal artifact contouring has little effect on the dose distribution of VMAT. However, it should be noted that the dose distribution may change depending on the contouring method in cases where the overlap between PTV and metal artifact areas is large

Vaginal Lymphoma with Immune Thrombocytopenic Purpura: An Unusual Case Report

The female genital tract is rarely the initial site of presentation in lymphoma or leukemia. We report a case of non-Hodgkin's lymphoma (NHL) presenting initially in the vagina. The patient, a 75-year-old woman, had a history of immune thrombocytopenic purpura (ITP). She presented with a chief complaint of genital bleeding and introital pain. On transvaginal ultrasonography, a vaginal tumor with an irregular wall was detected, and the internal echo showed a hypoechoic and echogenic pattern. Ultrasonography and magnetic resonance imaging (MRI) suggested that the vaginal tumor was likely to be a hematoma or a hemorrhagic tumor arising from ITP. Incision and resection for a hematoma or a hemorrhagic tumor were carried out in response to genital bleeding, introital pain, and pathological diagnosis. Postoperative microscopic examination confirmed that the tumor was a vaginal NHL. The final diagnosis using the Ann Arbor staging system was high-stage (stage IV) NHL. The patient received chemotherapy, and she remains in remission for 42 months after treatment

Differences between professionals in treatment planning for patients with stage III lung cancer using treatment-planning QA software

Background: The quality of treatment planning for stage III non-small cell lung cancer varies within and between facilities due to the different professions involved in planning. Dose estimation parameters were calculated using a feasibility dose-volume histogram (FDVH) implemented in the treatment planning quality assurance software PlanIQ. This study aimed to evaluate differences in treatment planning between occupations using manual FDVH-referenced treatment planning to identify their characteristics. Materials and methods: The study included ten patients with stage III non-small cell lung cancer, and volumetric-modulated arc therapy was used as the treatment planning technique. Fifteen planners, comprising five radiation oncologists, five medical physicists, and five radiological technologists, developed treatment strategies after referring to the FDVH. Results: Medical physicists had a higher mean dose at D98% of the planning target volume (PTV) and a lower mean dose at D2% of the PTV than those in other occupations. Medical physicists had the lowest irradiation lung volumes (V5 Gy and V13 Gy) compared to other professions, and radiation oncologists had the lowest V20 Gy and mean lung dose. Radiological technologists had the highest irradiation volumes for dose constraints at all indexes on the normal lung volume. Conclusions: The quality of the treatment plans developed in this study differed between occupations due to their background expertise, even when an FDVH was used as a reference. Therefore, discussing and sharing knowledge and treatment planning techniques among professionals is essential to determine the optimal treatment plan for each facility and patient

SPO11-Independent DNA Repair Foci and Their Role in Meiotic Silencing

In mammalian meiotic prophase, the initial steps in repair of SPO11-induced DNA double-strand breaks (DSBs) are required to obtain stable homologous chromosome pairing and synapsis. The X and Y chromosomes pair and synapse only in the short pseudo-autosomal regions. The rest of the chromatin of the sex chromosomes remain unsynapsed, contains persistent meiotic DSBs, and the whole so-called XY body undergoes meiotic sex chromosome inactivation (MSCI). A more general mechanism, named meiotic silencing of unsynapsed chromatin (MSUC), is activated when autosomes fail to synapse. In the absence of SPO11, many chromosomal regions remain unsynapsed, but MSUC takes place only on part of the unsynapsed chromatin. We asked if spontaneous DSBs occur in meiocytes that lack a functional SPO11 protein, and if these might be involved in targeting the MSUC response to part of the unsynapsed chromatin. We generated mice carrying a point mutation that disrupts the predicted catalytic site of SPO11 (Spo11YF/YF), and blocks its DSB-inducing activity. Interestingly, we observed foci of proteins involved in the processing of DNA damage, such as RAD51, DMC1, and RPA, both in Spo11YF/YFand Spo11 knockout meiocytes. These foci preferentially localized to the areas that undergo MSUC and form the so-called pseudo XY body. In SPO11-deficient oocytes, the number

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Risk factors of vaginal cuff infection in women undergoing laparoscopic hysterectomy for benign gynecological diseases

Aim This study aimed to identify the risk factors for vaginal cuff infection after laparoscopic hysterectomy for benign gynecological diseases. Methods We conducted a retrospective cohort study among 1559 Japanese women who underwent total laparoscopic hysterectomy (TLH) for benign indications between 2014 and 2018 at Teine Keijinkai Hospital in Sapporo, Japan. All patients received preoperative antibiotics based on appropriate timing, choice, and weight-based dosing. We assessed the risk factors of vaginal cuff infection after TLH, including demographic and clinical variables, and patient- and surgery-related factors, using univariable and multivariable logistic regression analyses. Results Among all the patients who underwent TLH, 71 cases of vaginal cuff infections (4.6%) were recorded. Univariate analyses showed that current smoking, pathological result of adenomyosis, use of Seprafilm as an antiadhesive material, white blood cell counts on postoperative day (POD) 2, C-reactive protein (CRP) level on POD2 and postoperative vaginal cuff hematoma were significantly associated with an increased risk of vaginal cuff infection. In multivariate analysis, current smoking, use of seprafilm, CRP level on POD2 and vaginal cuff hematoma were significantly associated with an increased risk of vaginal cuff infection. Conclusion Current smoking, use of seprafilm, CRP level on POD2 and vaginal cuff hematoma were identified as significant risk factors of vaginal cuff infection in the 30 days after surgery in Japanese women who underwent TLH for benign indications

Does the experience of the first assistant affect organ injuries in laparoscopic hysterectomy for benign diseases?

Purpose This study sought to explore whether the experience level of the first assistant surgeon influences perioperative organ injuries (ureteral, bladder, and intestinal injuries) in patients undergoing total laparoscopic hysterectomy (TLH) for benign diseases. We defined an experienced surgeon as a surgeon certified by the Skill Qualification Committee of the Japan Society of Gynecologic and Obstetric Endoscopy and Minimally Invasive Therapy or a surgeon with equivalent surgical skills. Methods We reviewed our surgical registry database of TLH for benign indications between 2014 and 2020 and only selected cases performed by an experienced primary surgeon. Patients were divided into two groups based on the experience level of the first assistant. Inverse probability of treatment weighting by propensity score, which was adjusted for patient and procedure characteristics, was used to examine differences in perioperative organ injuries according to the experience level of the first assistant. Results Among 1682 patients who underwent TLH, 18 organ injuries were found (0.83%). In the propensity score inverse probability of treatment weighting models, less experience of the first assistant had no significant impact on the occurrence of perioperative organ injuries (p = 0.348). Conclusion In TLH for benign indications at our hospital, given an experienced primary surgeon, the inclusion of a less experienced first assistant does not negatively affect the occurrence of perioperative organ injuries