Complications and failure after Kock continent ileostomy: A systematic review and meta-analysis.

BACKGROUND: A significant number of patients experience complications of the Kock pouch (KP) warranting revision or excision. This systematic review aimed to assess the pooled prevalence and risk factors for complications and failure of the KP. METHODS: This Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA)-compliant systematic review (CRD42023416961) searched PubMed, Scopus, and Web of Science for studies on adult patients with Kock continent ileostomy published after the year 2000. The main outcome measures were revision, complications, and failure of the KP. Risk factors for complications and failure were assessed using a meta-regression analysis. Risk of bias was assessed using the ROBINS-1 tool. A proportional meta-analysis of the main outcomes was performed. RESULTS: A total of 19 studies (2042 patients) were included. The weighted mean prevalence of complications was 60.4% [95% confidence interval (CI): 46.1-74.7%], of pouch revision was 46.6% (95% CI: 38.5-54.7%), and of pouch failure was 12.9% (95% CI: 9.3-16.4%). Studies conducted in the USA had a mean failure prevalence of 12.6% (95% CI: 6.2-18.9%) comparable to studies conducted in Europe (11.1%; 95% CI: 7.5-14.7%). Factors associated with higher complications were increased body mass index (BMI) and previous ileoanal pouch anastomosis (IPAA); however, these factors were not associated with increased pouch failure. CONCLUSIONS: The KP is a highly complex operation as shown by a pooled complication prevalence of 60%, and thus, it should be only performed by experienced surgeons. Despite the high prevalence of complications and need for revisional surgery, patients are keen to preserve their KP. Increased BMI and a previous failed IPAA are risk factors for pouch complications, but not failure.

The role of ureteric indocyanine green fluorescence in colorectal surgery: a retrospective cohort study.

BACKGROUND: Ureteric injury (UI) is an infrequent but serious complication of colorectal surgery. Prophylactic ureteric stenting is employed to avoid UI, yet its efficacy remains debated. Intraoperative indocyanine green fluorescence imaging (ICG-FI) has been used to facilitate ureter detection. This study aimed to investigate the role of ICG-FI in identification of ureters during colorectal surgery and its impact on the incidence of UI. METHODS: A retrospective cohort study involving 556 consecutive patients who underwent colorectal surgery between 2018 and 2023 assessed the utility of routine prophylactic ureteric stenting with adjunctive ICG-FI. Patients with ICG-FI were compared to those without ICG-FI. Demographic data, operative details, and postoperative morbidity were analyzed. Statistical analysis included univariable regression. RESULTS: Ureteric ICG-FI was used in 312 (56.1%) patients, whereas 43.9% were controls. Both groups were comparable in terms of demographics except for a higher prevalence of prior abdominal surgeries in the ICG-FI group. Although intraoperative visualization was significantly higher in the ICG-FI group (95.3% vs 89.1%; p = 0.011), the incidence of UI was similar between groups (0.3% vs 0.8%; p = 0.585). Postoperative complications were similar between the two groups. Median stent insertion time was longer in the ICG-FI group (32 vs 25 min; p = 0.001). CONCLUSION: Ureteric ICG-FI improved intraoperative visualization of the ureters but was not associated with a reduced UI rate. Median stent insertion time increased with use of ureteric ICG-FI, but total operative time did not. Despite its limitations, this study is the largest of its kind suggesting that ureteric ICG-FI may be a valuable adjunct to facilitate  ureteric visualization during colorectal surgery.

Gracilis muscle interposition for pouch-vaginal fistulas: a single-centre cohort study and literature review.

BACKGROUND: First described by Parks and Nicholls in 1978, the ileal pouch-anal anastomosis (IPAA) has revolutionized the treatment of mucosal ulcerative colitis (MUC) and familial adenomatous polyposis (FAP). IPAA is fraught with complications, one of which is pouch-vaginal fistulas (PVF), a rare but challenging complication noted in 3.9-15% of female patients. Surgical treatment success approximates 50%. Gracilis muscle interposition (GMI) is a promising technique that has shown good results with other types of perineal fistulas. We present the results from our institution and a comprehensive literature review. METHODS: A retrospective observational study including all patients with a PVF treated with GMI at our institution from December 2018-January 2000. Primary outcome was complete healing after ileostomy closure. RESULTS: Nine patients were included. Eight of nine IPAAs (88.9%) were performed for MUC, and one for FAP. A subsequent diagnosis of Crohn's disease was made in five patients. Initial success occurred in two patients (22.2%), one patient was lost to follow-up and seven patients, after further procedures, ultimately achieved healing (77.8%). Four of five patients with Crohn's achieved complete healing (80%). CONCLUSION: Surgical healing rates quoted in the literature for PVFs are approximately 50%. The initial healing rate was 22.2% and increased to 77.8% after subsequent surgeries, while it was 80% in patients with Crohn's disease. Given this, gracilis muscle interposition may have a role in the treatment of pouch-vaginal fistulas.

A molecular staging model for accurately dating the endometrial biopsy.

Natural variability in menstrual cycle length, coupled with rapid changes in endometrial gene expression, makes it difficult to accurately define and compare different stages of the endometrial cycle. Here we develop and validate a method for precisely determining endometrial cycle stage based on global gene expression. Our 'molecular staging model' reveals significant and remarkably synchronised daily changes in expression for over 3400 endometrial genes throughout the cycle, with the most dramatic changes occurring during the secretory phase. Our study significantly extends existing data on the endometrial transcriptome, and for the first time enables identification of differentially expressed endometrial genes with increasing age and different ethnicities. It also allows reinterpretation of all endometrial RNA-seq and array data that has been published to date. Our molecular staging model will significantly advance understanding of endometrial-related disorders that affect nearly all women at some stage of their lives, such as heavy menstrual bleeding, endometriosis, adenomyosis, and recurrent implantation failure.

Long-term follow-up of bilateral gracilis reconstruction following extra-levator abdominoperineal excision.

INTRODUCTION: Colorectal operations such as an extra-levator abdominoperineal (elAPE) excision for locally advanced or recurrent cancer create a significant perineal tissue deficit. Options for perineal reconstruction include bilateral pedicled gracilis muscle flaps (BPGMF). Fashioning the gracili into a 'weave' creates a muscular sling that supports pelvic contents and is a novel technique. Our series reports the outcomes of the BPGMF in 50 patients undergoing surgery for pelvic cancer. METHOD: This is a retrospective, single-centre study of patients undergoing reconstruction of perineal defects using BPGMF. All surgeries took place between January 2008 and February 2021. The primary outcome measured was perineal wound healing. The secondary outcomes measured were complications of surgical sites and length of hospital stay (short term), flap integrity on follow-up imaging and functional outcomes (long term). RESULTS: Fifty patients underwent perineal reconstruction using BPGMF (26 males). The median age was 62 years. The 30-day mortality was 2% (n = 1). The average follow-up period was 2 years. Complete perineal wound healing was 86% (42/49) at outpatient follow-up. Complication rates for the donor site and reconstructed site were 14% and 22%, respectively. Complications included infection (2% donor site, 12% perineum), haematoma (4% donor site), dehiscence (2% donor site, 4% perineum) and seroma (3% donor site, 2% perineum). CONCLUSION: BPGMF offers a reliable and technically simple muscle flap to reconstruct large perineal defects. The muscle flap integrity appears maintained on follow-up imaging despite a lack of flap monitoring tools. This cohort had minimal functional impairment following BPGMF.

Genetic risk factors for endometriosis near estrogen receptor 1 and coexpression of genes in this region in endometrium.

The etiology and pathogenesis of endometriosis are complex with both genetic and environmental factors contributing to disease risk. Genome-wide association studies (GWAS) have identified multiple signals in the estrogen receptor 1 (ESR1) region associated with endometriosis and other reproductive traits and diseases. In addition, candidate gene association studies identified signals in the ESR1 region associated with endometriosis risk suggesting genetic regulation of genes in this region may be important for reproductive health. This study aimed to investigate hormonal and genetic regulation of genes in the ESR1 region in human endometrium. Changes in serum oestradiol and progesterone concentrations and expression of hormone receptors ESR1 and progesterone receptor (PGR) were assessed in endometrial samples from 135 women collected at various stages of the menstrual cycle. Correlation between hormone concentrations, receptor expression and expression of genes in the ESR1 locus was investigated. The effect of endometriosis risk variants on expression of genes in the region was analyzed to identify gene targets. Hormone concentrations and receptor expression varied significantly across the menstrual cycle. Expression of genes in the ESR1 region correlated with progesterone concentration; however, they were more strongly correlated with expression of ESR1 and PGR suggesting coregulation of genes. There was no evidence that endometriosis risk variants directly regulated expression of genes in the region. Limited sample size and cellular heterogeneity in endometrial tissue may impact the ability to detect significant genetic effects on gene expression. Effects of these variants should be validated in a larger dataset and in relevant individual cell types.

Superficial peritoneal endometriotic lesions are histologically diverse and rarely demonstrate menstrual cycle synchronicity with matched eutopic endometrium.

STUDY QUESTION: Do menstrual cycle-dependent changes occur in the histological appearance of superficial peritoneal endometriotic lesions, and are they equivalent to those observed in the eutopic endometrium? SUMMARY ANSWER: Only a small subset of superficial peritoneal endometriotic lesions exhibits some histological features in phase with menstrual cycle-related changes observed in eutopic endometrium. WHAT IS KNOWN ALREADY: Endometriotic lesions are frequently described as implants that follow menstrual cycle-related changes in morphology, as per the eutopic endometrium. This concept has been widely accepted despite the lack of conclusive published evidence. STUDY DESIGN, SIZE, DURATION: This was a retrospective cohort study of 42 patients, from across the menstrual cycle, with surgically and histologically confirmed endometriosis. Patients were a subset selected from a larger endometriosis study being conducted at the Royal Women's Hospital, Melbourne since 2012. PARTICIPANTS/MATERIALS, SETTING, METHODS: Histological features of epithelium, stroma and gland morphology were examined in haematoxylin and eosin stained sections of superficial peritoneal endometriotic lesions and matched eutopic endometrium (menstrual: n = 4, proliferative: n = 11, secretory: n = 17, hormone-treated: n = 10). At least two biopsies (average = 4, range = 2-8 biopsies) and a matched endometrial sample were analysed for each patient and results were presented per endometriotic gland profile (n = 1051). Data were analysed using mixed effects logistic regression to account for multiple patients and multiple endometriotic biopsies, each with multiple endometriotic gland profiles. This model also enabled analysis of endometriotic lesions versus eutopic endometrium. MAIN RESULTS AND THE ROLE OF CHANCE: There was considerable inter- and intra-patient variability in the morphology of superficial peritoneal endometriotic lesions. Menstrual cycle-associated changes were only observed for some features in a subset of endometriotic gland profiles. The proportion of endometriotic gland profiles with epithelial mitoses significantly increased in the proliferative phase (18% of gland profiles) relative to the menstrual phase (0% of endometriotic gland profiles) (odds ratios (OR) 9.30; 95% confidence intervals (CI) = 3.71-23.32; P < 0.001). Fewer blood-filled gland lumens were observed in the secretory phase (45% of endometriotic gland profiles) compared to the menstrual phase (67% of endometriotic gland profiles) (OR, 0.30; 95% CI = 0.11-0.79; P = 0.015). The features of the eutopic endometrium analysed in this study did not reflect the results in matched endometriotic lesions (P > 0.05). LARGE SCALE DATA: Not applicable. LIMITATIONS, REASONS FOR CAUTION: This study focused on features observed in sections of superficial peritoneal lesions and these may differ from features of deep infiltrating endometriosis or ovarian endometriomas. Cycle phases were limited to menstrual, proliferative and secretory phases to allow appropriate statistical modelling. WIDER IMPLICATIONS OF THE FINDINGS: This study highlights heterogeneity in the histological characteristics of superficial peritoneal lesions. It challenges the assumption that lesion morphology consistently reflects menstrual cycle-associated changes. STUDY FUNDING/COMPETING INTEREST(S): Research reported in this publication was supported in part by National Health and Medical Research Council (NHMRC) project grants GNT1012245, GNT1105321 and GNT1026033 (P.A.W.R., J.E.G. and S.J.H.-C.). There are no competing interests.

Clinical summary guide: reproduction in women with previous abdominopelvic radiotherapy or total body irradiation.

STUDY QUESTION: What is the evidence to guide the management of women who wish to conceive following abdominopelvic radiotherapy (AP RT) or total body irradiation (TBI)? SUMMARY ANSWER: Pregnancy is possible, even following higher doses of post-pubertal uterine radiation exposure; however, it is associated with adverse reproductive sequelae and pregnancies must be managed in a high-risk obstetric unit. WHAT IS KNOWN ALREADY: In addition to primary ovarian insufficiency, female survivors who are treated with AP RT and TBI are at risk of damage to the uterus. This may impact on its function and manifest as adverse reproductive sequelae. STUDY DESIGN SIZE DURATION: A review of the literature was carried out and a multidisciplinary working group provided expert opinion regarding assessment of the uterus and obstetric management. PARTICIPANTS/MATERIALS SETTING METHODS: Reproductive outcomes for postpubertal women with uterine radiation exposure in the form of AP RT or TBI were reviewed. This included Pubmed listed peer-reviewed publications from 1990 to 2019, and limited to English language.. MAIN RESULTS AND THE ROLE OF CHANCE: The prepubertal uterus is much more vulnerable to the effects of radiation than after puberty. Almost all available information about the impact of radiation on the uterus comes from studies of radiation exposure during childhood or adolescence.An uncomplicated pregnancy is possible, even with doses as high as 54 Gy. Therefore, tumour treatment doses alone cannot at present be used to accurately predict uterine damage. LIMITATIONS REASONS FOR CAUTION: Much of the data cannot be readily extrapolated to adult women who have had uterine radiation and the publications concerning adult women treated with AP RT are largely limited to case reports. WIDER IMPLICATIONS OF THE FINDINGS: This analysis offers clinical guidance and assists with patient counselling. It is important to include patients who have undergone AP RT or TBI in prospective studies to provide further evidence regarding uterine function, pregnancy outcomes and correlation of imaging with clinical outcomes. STUDY FUNDING/COMPETING INTERESTS: This study received no funding and there are no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

A Monte Carlo model of synchrotron radiotherapy shows good agreement with experimental dosimetry measurements: Data from the imaging and medical beamline at the Australian Synchrotron.

Experimental measurement of Synchrotron Radiotherapy (SyncRT) doses is challenging, especially for Microbeam Radiotherapy (MRT), which is characterised by very high dynamic ranges with spatial resolutions on the micrometer scale. Monte Carlo (MC) simulation is considered a gold standard for accurate dose calculation in radiotherapy, and is therefore routinely relied upon to produce verification data. We present a MC model for Australian Synchrotron's Imaging and Medical Beamline (IMBL), which is capable of generating accurate dosimetry data to inform and/or verify SyncRT experiments. Our MC model showed excellent agreement with dosimetric measurement for Synchrotron Broadbeam Radiotherapy (SBBR). Our MC model is also the first to achieve validation for MRT, using two methods of dosimetry, to within clinical tolerances of 5% for a 20×20 mm2 field size, except for surface measurements at 5 mm depth, which remained to within good agreement of 7.5%. Our experimental methodology has allowed us to control measurement uncertainties for MRT doses to within 5-6%, which has also not been previously achieved, and provides a confidence which until now has been lacking in MRT validation studies. The MC model is suitable for SyncRT dose calculation of clinically relevant field sizes at the IMBL, and can be extended to include medical beamlines at other Synchrotron facilities as well. The presented MC model will be used as a validation tool for treatment planning dose calculation algorithms, and is an important step towards veterinary SyncRT trials at the Australian Synchrotron.

Lyophilized Iron Oxide Nanoparticles Encapsulated in Amphotericin B: A Novel Targeted Nano Drug Delivery System for the Treatment of Systemic Fungal Infections.

We formulated and tested a targeted nanodrug delivery system to help treat life-threatening invasive fungal infections, such as cryptococcal meningitis. Various designs of iron oxide nanoparticles (IONP) (34-40 nm) coated with bovine serum albumin and coated and targeted with amphotericin B (AMB-IONP), were formulated by applying a layer-by-layer approach. The nanoparticles were monodispersed and spherical in shape, and the lead formulation was found to be in an optimum range for nanomedicine with size (≤36 nm), zeta potential (-20 mV), and poly dispersity index (≤0.2), and the drug loading was 13.6 ± 6.9 µg of AMB/mg of IONP. The drug release profile indicated a burst release of up to 3 h, followed by a sustained drug release of up to 72 h. The lead showed a time-dependent cellular uptake in C. albicans and C. glabrata clinical isolates, and exhibited an improved efficacy (16-25-fold) over a marketed conventional AMB-deoxycholate product in susceptibility testing. Intracellular trafficking of AMB-IONP by TEM and confocal laser scanning microscopy confirmed the successful delivery of the AMB payload at and/or inside the fungal cells leading to potential therapeutic advantages over the AMB-deoxycholate product. A short-term stability study at 5 °C and 25 °C for up to two months showed that the lyophilized form was stable.

Endometrial uNK cell counts do not predict successful implantation in an IVF population.

STUDY QUESTION: Are uterine natural killer (uNK) cell numbers and their distribution relative to endometrial arterioles altered in women with recurrent implantation failure (RIF) compared to women with embryo implantation success (IS)? SUMMARY ANSWER: uNK cell numbers and their distribution relative to endometrial arterioles are not significantly different in women with RIF compared to women in whom embryo implantation occurs successfully following IVF. WHAT IS ALREADY KNOWN: uNK cells are regulators of decidual angiogenesis and spiral arteriole remodelling during early pregnancy. Although some studies have shown that uNK cell numbers may be altered in women with RIF, the methods used to measure uNK cell numbers have proven inconsistent, making reproduction of these results difficult. It is unclear, therefore, whether the results reported so far are reproducible. Moreover, it is not known how uNK cell numbers may impact IVF outcomes. Despite the lack of conclusive evidence, uNK cell numbers are often evaluated as a prognostic criterion in women undergoing assisted reproductive procedures. STUDY DESIGN, SIZE, DURATION: Endometrial pipelle biopsies were collected 6-8 days post-LH surge in natural cycles from women with RIF (n = 14), women with IS (n = 11) and women with potential RIF at the time of the study (PRIF; n = 9) from 2013 to 2015. PARTICIPANTS/MATERIALS, SETTING, METHODS: uNK cells (i.e. CD56+ and/or CD16+ phenotypes) and their distribution relative to endometrial arterioles were investigated by standard immunohistochemistry protocols and quantified using Aperio ScanScopeXT images digitized by ImageJ and deconvoluted into binary images for single cell quantification using a Gaussian Blur and Yen algorithm. MAIN RESULTS AND THE ROLE OF CHANCE: There was no significant difference in the cell density of CD56+ or CD16+ uNK cells in women with RIF compared to women with IS or PRIF. There was a higher proportion of uNK cells in the distal regions compared to the regions closest to the arterioles in all patient groups. Further, we identified a significant reduction in uNK cell density in women who had a previous pregnancy compared to those who had not, regardless of their current implantation status. LARGE SCALE DATA: Not applicable. LIMITATIONS, REASONS FOR CAUTION: Spiral arterioles could not always be accurately identified by digital image analysis; therefore, all endometrial arterioles were selected and analysed. Patient numbers for the study were low. However, as the clinical phenotypes of each patient were well defined, and endometrial dating was accurately determined by three independent pathologists, differences between patient groups with respect to the uNK numbers and distribution should have been measurable if uNK cell counts were to be useful as a prognostic marker of RIF. WIDER IMPLICATIONS OF THE FINDINGS: Our findings demonstrate that CD56+ and CD16+ uNK cell numbers are not significantly different in women with RIF in a typical cohort of women undergoing IVF. Further, prior pregnancy was associated with a significantly reduced number of uNK cells in both the RIF and IS patient groups, suggestive of a long-term pregnancy induced suppression of uNK cells. Combined, these findings do not support the clinical value of using uNK cell numbers as a prognostic indicator of implantation success with IVF treatment. STUDY FUNDING/COMPETING INTEREST(S): Funding for this work was provided by Royal Women's Hospital Foundation. P.P. was supported by an NHMRC Early Career Fellowship [TF 11/14] and W.T.T. was supported by an NHMRC Postgraduate Scholarship [1055814]. The authors do not have any competing interests with this study.

Generation of immortalized human endometrial stromal cell lines with different endometriosis risk genotypes.

Endometriotic lesions are composed in part of endometrial-like stromal cells, however, there is a shortage of immortalized human endometrial stromal cultures available for research. As genetic factors play a role in endometriosis risk, it is important that genotype is also incorporated into analysis of pathological mechanisms. Human telomerase reverse transcriptase (hTERT) immortalization (using Lenti-hTERT-green fluorescent protein virus) took place following genotype selection; 13 patients homozygous for either the risk or non-risk 'other' allele for one or more important endometriosis risk single nucleotide polymorphism on chromosome 1p36.12 (rs3820282, rs56318008, rs55938609, rs12037376, rs7521902 or rs12061255). Short tandem repeat DNA profiling validated that donor tissue matched that of the immortalized cell lines and confirmed that cultures were genetically novel. Expression of morphological markers (vimentin and cytokeratin) and key genes of interest (telomerase, estrogen and progesterone receptors and LINC00339) were examined and functional assays for cell proliferation, steroid hormone and inflammatory responses were performed for 7/13 cultures. All endometrial stromal cell lines maintained their fibroblast-like morphology (vimentin-positive) and homozygous endometriosis-risk genotype following introduction of hTERT. Furthermore, the new stromal cultures demonstrated positive and diverse responses to hormones (proliferation and decidualisation changes) and inflammation (dose-dependent response), while maintaining hormone receptor expression. In conclusion, we successfully developed a range of human endometrial stromal cell lines that carry important endometriosis-risk alleles. The wider implications of this approach go beyond advancing endometriosis research; these cell lines will be valuable tools for multiple endometrial pathologies offering a level of genetic and phenotypic diversity not previously available.

Social media for dissemination and public engagement in neurosurgery-the example of Brainbook.

BACKGROUND: Public engagement has become one of the most effective tools in gaining feedback and perspectives from members of the public, involving patients with decisions, and inspiring young people to carry the medical profession forwards. Brainbook is a multi-platform, social media-based resource that was created specifically to enhance public engagement in neurosurgery and results from one of its case discussions will be reported in this paper. METHODS: A Brainbook case was created in collaboration with the NIHR Global Health Research Group on Neurotrauma and presented over 3 days (23-25 February 2018). YouTube videos were created depicting the management of an acute subdural haematoma using patient interviews, medical illustration, consultant-led discussion and operative footage. Content was shared across all Brainbook social media platforms and analytics were gathered through social media applications. RESULTS: Over a 72-hour time period, and across multiple social media accounts, 101,418 impressions were achieved (defined as penetrance onto individual media feeds and total views of the content), with active discussion on social media. CONCLUSIONS: Neurosurgical content published across multiple social media outlets represents an encouraging and exciting potential for global engagement across multiple audiences. Social media can be an effective method of not only disseminating neurosurgical knowledge, but activating and engaging the public, allied healthcare professionals, medical students and neurosurgeons.

Characterization of Diffuse Intrinsic Pontine Glioma Radiosensitivity using Synchrotron Microbeam Radiotherapy and Conventional Radiation Therapy In Vitro.

Synchrotron microbeam radiation therapy is a promising preclinical radiotherapy modality that has been proposed as an alternative to conventional radiation therapy for diseases such as diffuse intrinsic pontine glioma (DIPG), a devastating pediatric tumor of the brainstem. The primary goal of this study was to characterize and compare the radiosensitivity of two DIPG cell lines (SF7761 and JHH-DIPG-1) to microbeam and conventional radiation. We hypothesized that these DIPG cell lines would exhibit differential responses to each radiation modality. Single cell suspensions were exposed to microbeam (112, 250, 560, 1,180 Gy peak dose) or conventional (2, 4, 6 and 8 Gy) radiation to produce clonogenic cell-survival curves. Apoptosis induction and the cell cycle were also analyzed five days postirradiation using flow cytometry. JHH-DIPG-1 cells displayed greater radioresistance than SF7761 to both microbeam and conventional radiation, with higher colony formation and increased accumulation of G2/M-phase cells. Apoptosis was significantly increased in SF7761 cells compared to JHH-DIPG-1 after microbeam irradiation, demonstrating cell-line specific differential radiosensitivity to microbeam radiation. Additionally, biologically equivalent doses to microbeam and conventional radiation were calculated based on clonogenic survival, furthering our understanding of the response of cancer cells to these two radiotherapy modalities.

Characterization of Diffuse Intrinsic Pontine Glioma Radiosensitivity using Synchrotron Microbeam Radiotherapy and Conventional Radiation Therapy In Vitro.

Synchrotron microbeam radiation therapy is a promising preclinical radiotherapy modality that has been proposed as an alternative to conventional radiation therapy for diseases such as diffuse intrinsic pontine glioma (DIPG), a devastating pediatric tumor of the brainstem. The primary goal of this study was to characterize and compare the radiosensitivity of two DIPG cell lines (SF7761 and JHH-DIPG-1) to microbeam and conventional radiation. We hypothesized that these DIPG cell lines would exhibit differential responses to each radiation modality. Single cell suspensions were exposed to microbeam (112, 250, 560, 1,180 Gy peak dose) or conventional (2, 4, 6 and 8 Gy) radiation to produce clonogenic cell-survival curves. Apoptosis induction and the cell cycle were also analyzed five days postirradiation using flow cytometry. JHH-DIPG-1 cells displayed greater radioresistance than SF7761 to both microbeam and conventional radiation, with higher colony formation and increased accumulation of G2/M-phase cells. Apoptosis was significantly increased in SF7761 cells compared to JHH-DIPG-1 after microbeam irradiation, demonstrating cell-line specific differential radiosensitivity to microbeam radiation. Additionally, biologically equivalent doses to microbeam and conventional radiation were calculated based on clonogenic survival, furthering our understanding of the response of cancer cells to these two radiotherapy modalities.