Comparing Performance of Spectral Image Analysis Approaches for Detection of Cellular Signals in Time-Lapse Hyperspectral Imaging Fluorescence Excitation-Scanning Microscopy

Hyperspectral imaging (HSI) technology has been applied in a range of fields for target detection and mixture analysis. While HSI was originally developed for remote sensing applications, modern uses include agriculture, historical document authentication, and medicine. HSI has also shown great utility in fluorescence microscopy. However, traditional fluorescence microscopy HSI systems have suffered from limited signal strength due to the need to filter or disperse the emitted light across many spectral bands. We have previously demonstrated that sampling the fluorescence excitation spectrum may provide an alternative approach with improved signal strength. Here, we report on the use of excitation-scanning HSI for dynamic cell signaling studies-in this case, the study of the second messenger Ca2+. Time-lapse excitation-scanning HSI data of Ca2+ signals in human airway smooth muscle cells (HASMCs) were acquired and analyzed using four spectral analysis algorithms: linear unmixing (LU), spectral angle mapper (SAM), constrained energy minimization (CEM), and matched filter (MF), and the performances were compared. Results indicate that LU and MF provided similar linear responses to increasing Ca2+ and could both be effectively used for excitation-scanning HSI. A theoretical sensitivity framework was used to enable the filtering of analyzed images to reject pixels with signals below a minimum detectable limit. The results indicated that subtle kinetic features might be revealed through pixel filtering. Overall, the results suggest that excitation-scanning HSI can be employed for kinetic measurements of cell signals or other dynamic cellular events and that the selection of an appropriate analysis algorithm and pixel filtering may aid in the extraction of quantitative signal traces. These approaches may be especially helpful for cases where the signal of interest is masked by strong cellular autofluorescence or other competing signals.

Tinospora cordifolia modulates the seminal parameters, leakage of intracellular enzymes and seminal antioxidants in equilibrated and cryopreserved semen of Sahiwal bulls

The present study was undertaken to assess the effects of stem extract of Tinospora cordifolia (Giloy or Guduchi) in the semen extender on seminal parameters, leakage of intracellular enzymes and antioxidants in semen of Sahiwal bull. A total of 48 ejaculates from four bulls were selected for the study. Spermatozoa of 25×10⁶ were incubated in 100, 300 and 500 μg of stem extract of Guduchi as Gr II, III and IV, respectively and pre-freeze and post-thaw semen samples were analysed for seminal parameters (motility, viability, total sperm abnormality; TSA, plasma membrane integrity; PMI, and acrosomal integrity; AcI), intracellular enzymes (aspartate aminotransferase; AST and lactate dehydrogenase; LDH) and seminal antioxidants (superoxide dismutase; SOD and catalase) in comparison with an untreated control group (Gr I). The results revealed that stem extract treated semen had significantly (p<0.05) higher motility, viability, PMI, AcI, SOD and catalase and had significantly (p<0.05) lower TSA, AST and LDH compared to those in untreated control group at pre-freeze and post-thaw stages. Semen treated with 100 μg stem extract /25×10⁶ spermatozoa had significantly (p<0.05) higher motility, viability, PMI, AcI, SOD and catalase and had significantly (p<0.05) lower TSA, AST and LDH compared to those in control, 300, and 500 μg treated groups at pre-freeze and post-thaw stages. Further, these seminal parameters and antioxidants were showing decreasing trend and TSA and leakage of intra-cellular enzymes were showing increasing trend from Gr II to Gr IV at pre-freeze and post-thaw stages. Thus, 100 μg/25×10⁶ spermatozoa were optimum or suitable dose for cryopreservation of Sahiwal bull semen. The study concluded that T. cordifolia stem extract 100 μg/25×10⁶ spermatozoa in the semen extender can be effectively utilized to reduce the oxidative stress and improve the pre-freeze and post-thaw seminal parameters in Sahiwal bull. However, further studies on effects of different concentrations of stem extract on in-vitro or in-vivo fertility trials are to be conducted to assess the impact of the stem extract supplementation in the semen extender on field pregnancy outcome in bovine species.

Measurement of agonist-induced Ca2+ signals in human airway smooth muscle cells using excitation scan-based hyperspectral imaging and image analysis approaches

Ca²⁺ and cAMP are ubiquitous second messengers known to differentially regulate a variety of cellular functions over a wide range of timescales. Studies from a variety of groups support the hypothesis that these signals can be localized to discrete locations within cells, and that this subcellular localization is a critical component of signaling specificity. However, to date, it has been difficult to track second messenger signals at multiple locations. To overcome this limitation, we utilized excitation scan-based hyperspectral imaging approaches to track second messenger signals as well as labeled cellular structures and/or proteins in the same cell. We have previously reported that hyperspectral imaging techniques improve the signal-to-noise ratios of both fluorescence measurements, and are thus well suited for the measurement of localized Ca²⁺ signals. We investigated the spatial spread and intensities of agonist-induced Ca²⁺ signals in primary human airway smooth muscle cells (HASMCs) using the Ca²⁺ indicator Cal520. We measured responses triggered by three agonists, carbachol, histamine, and chloroquine. We utilized custom software coded in MATLAB and Python to assess agonist induced changes in Ca²⁺ levels. Software algorithms removed the background and applied correction coefficients to spectral data prior to linear unmixing, spatial and temporal filtering, adaptive thresholding, and automated region of interest (ROI) detection. All three agonists triggered transient Ca²⁺ responses that were spatially and temporally complex. We are currently analyzing differences in both ROI area and intensity distributions triggered by these agonists. This work was supported by NIH awards P01HL066299, K25HL136869, and R01HL137030 and NSF award MRI1725937.

Low-Dose-Rate versus High-Dose-Rate intracavitary brachytherapy in cervical cancer - Final Results of a Phase III randomized trial

PURPOSE

Intracavitary brachytherapy using High-Dose-Rate (HDR) and Low-dose-rate (LDR) in cervical cancer has been utilized. We report the long-term final results of a large randomized trial in terms of toxicities and efficacy.

METHODS AND MATERIALS

Between 1996 to 2005, 816 patients were randomized to LDR (n = 441 patients) or HDR brachytherapy (n = 369 patients) stratified by FIGO Stage grouping. Patients with Stage I-II received external irradiation of 40 Gy in 20 fractions (with midline block (MLB)) followed by either 2 LDR Intracavitary applications of 30 Gy to point A (2-3 weeks apart) or 5 HDR Intracavitary applications of 7 Gy to point A once weekly. Patients with Stage III received 50 Gy in 25 fractions (with MLB after 40 Gy) followed by either one application of LDR 30 Gy to point A or three applications of HDR 7 Gy to point A once weekly.

RESULTS

With a median follow-up was 64 months (interquartile range [IQR]: 21 - 111), moderate to severe rectal and bladder complications were higher in LDR arm as compared to HDR arm (9.7% vs. 3.6%; p = 0.02) and (10.5% vs. 5.5%; p = 0.06) for Stage I-II. No difference in rectal or bladder complications for Stage III patients. Disease free and overall survivals were similar in both the arms for all stages.

CONCLUSIONS

HDR intracavitary brachytherapy with 7 Gy per fraction weekly is superior to LDR in terms of late rectal and bladder complications. Local control rates and survivals are similar irrespective of stages.

Nur77 Attenuates Inflammasome Activation by Inhibiting Caspase-1 Expression in Pulmonary Vascular Endothelial Cells

Inflammasomes are intracellular multiprotein complexes that help trigger and maintain the inflammatory response as part of the innate immune system. Recently, it has been increasingly recognized that aberrant inflammasome activation is critically involved endothelial dysfunction in a variety of human diseases, such as atherosclerosis, acute lung injury (ALI), and type 2 diabetes. The molecular mechanisms underlying endothelial inflammasome activation, however, are not completely elucidated. In the present study, we identified orphan nuclear receptor Nur77 as a novel regulator in controlling inflammasome activation in vascular endothelial cells (ECs). We demonstrated that LPS-induced inflammasome activation was significantly inhibited by ectopic overexpression of Nur77, predominantly through transcriptionally suppression of caspase-1 expression in vascular ECs. Consistent with this observation, we found that LPS-induced inflammasome activation was significantly augmented in lung ECs isolated from Nur77 knockout (KO) mice. Mechanistically, we showed that Nur77-induced inhibition of caspase-1 expression was due to an inhibition of Interferon Regulatory Factor 1 (IRF1) expression and its subsequent binding to the caspase-1 promoter. Importantly, in a mouse model of LPS-induced acute lung injury (ALI), Nur77 KO led to a marked activation of caspase-1 in the lung, increased alveolar and circulating IL-1β levels, and exacerbated ALI, all of which were substantially inhibited by administration of caspase-1 inhibitor. Together, our results support an important role for Nur77 in controlling inflammasome activation in vascular ECs and suggest that Nur77 could be a novel therapeutic target for the treatment of human diseases associated with aberrant inflammasome activation, such as ALI and atherosclerosis.

Breeding biology of Malabar Tree Toad Pedostibes tuberculosus (Anura: Bufonidae) from Castle Rock, Karnataka, India

The Malabar Tree Toad Pedostibes tuberculosus Günther, 1876 is an endemic and endangered species from the Western Ghats biodiversity hotspot, however, its reproductive biology is barely understood.  In 2018, we opportunistically encountered a breeding aggregation of P. tuberculosus at Castlerock, Karnataka, and recorded its breeding behavior.  We found P. tuberculosus in the northern Western Ghats to aggregate in choruses and breed for a short duration (a couple of nights).  Males physically competed in short duels to gain access to females.  The males clasped the females around the armpits in a tight axillary amplexus lasting an entire night.  The female in an overnight amplexus laid approximately 150 eggs.  We observed the tadpoles to rapidly develop and complete metamorphosis within a month.  We highlight the variation in reproductive traits in populations of P. tuberculosus distributed along the Western Ghats biodiversity hotspot which will aid in conservation and systematics of this species group. 

MicroRNA-638 inhibits human airway smooth muscle cell proliferation and migration through targeting cyclin D1 and NOR1

Abnormal airway smooth muscle cell (ASMC) proliferation and migration contribute significantly to increased ASM mass associated with asthma. MicroRNA (miR)-638 is a primate-specific miRNA that plays important roles in development, DNA damage repair, hematopoiesis, and tumorigenesis. Although it is highly expressed in ASMCs, its function in ASM remodeling remains unknown. In the current study, we found that in response to various mitogenic stimuli, including platelet-derived growth factor-two B chains (PDGF-BB), transforming growth factor β1, and fetal bovine serum, the expression of miR-638, as determined by quantitative real-time polymerase chain reaction (qRT-PCR), was significantly downregulated in the proliferative human ASMCs. Both gain- and loss-of-function studies were performed to study the role of miR-638 in ASMC proliferation and migration. We found that adenovirus-mediated miR-638 overexpression markedly inhibits ASMC proliferation and migration, while ablation of miR-638 by anti-miR-638 markedly increases cell proliferation and migration, as determined by WST-8 proliferation and scratch wound assays. Dual-luciferase reporter assay, qRT-PCR, and immunoblot analysis were used to investigate the effects of miR-638 on the expression of the downstream target genes in ASMCs. Our results demonstrated that miR-638 overexpression significantly reduced the expression of downstream target cyclin D1 and NOR1, both of which have been shown to be essential for cell proliferation and migration. Together, our study provides the first in vitro evidence highlighting the antiproliferative and antimigratory roles of miR-638 in human ASMC remodeling and suggests that targeted overexpression of miR-638 in ASMCs may provide a novel therapeutic strategy for preventing ASM hyperplasia associated with asthma.

The Effect of the Canine ABCB1-1Δ Mutation on Sedation after Intravenous Administration of Acepromazine

BACKGROUND

Dog breeds with the ABCB1-1Δ mutation have substantially truncated nonfunctional P-glycoprotein. Dogs homozygous for this mutation (mut/mut) are susceptible to the toxic adverse effects of ivermectin, loperamide, and vincristine. Anecdotal reports suggested ABCB1 mut/mut dogs showed increased depth and duration of acepromazine sedation.

HYPOTHESIS/OBJECTIVES

That ABCB1 mut/mut dogs have increased depth and duration of sedation after acepromazine IV compared to normal dogs (nor/nor).

ANIMALS

Twenty-nine rough-coated collies were divided into 3 groups of dogs based on their ABCB1 genotype: 10 mut/mut, 10 mut/nor, and 9 nor/nor.

METHODS

Dogs were given 0.04 mg/kg of acepromazine IV. Level of sedation, heart rate, respiratory rate, and blood pressure were recorded for 6 hours after acepromazine administration. Area under the curves (AUCs) of the normalized sedation score results were calculated and compared.

RESULTS

The median sedation scores for ABCB1 mut/mut dogs were higher than nor/nor dogs at all time points and were higher in mut/nor dogs for the first 2 hours. These differences were not found to be significant for any individual time point (P > .05). The median sedation score AUC for mut/mut dogs was significantly higher than nor/nor dogs (P = .028), but the AUC for mut/nor dogs was not (P = .45). There were no significant differences between groups for heart rate, respiratory rate, and blood pressure (P > .05).

CONCLUSIONS AND CLINICAL IMPORTANCE

In ABCB1 mut/mut dogs acepromazine dose rates should be reduced and careful monitoring performed during sedation.

Reirradiation using high-dose-rate brachytherapy in recurrent carcinoma of uterine cervix

PURPOSE

To assess the feasibility of reirradiation with image-based high-dose-rate brachytherapy in previously irradiated patients with recurrent carcinoma of uterine cervix.

METHODS AND MATERIALS

Thirty previously irradiated patients diagnosed with central recurrence were treated with reirradiation. Martinez Universal Perineal Implant Template was used in 24 patients and Vienna applicator in 6 patients. Median interval between two radiation schedules was 25 months. Median delivered dose was 42 Gy equivalent dose at 2 Gy (EQD2; interquartile range, 37-46 Gy EQD2).

RESULTS

All 30 patients tolerated reirradiation well. Complete response was seen in 23 (76%) patients. With a median followup of 25 months, 2-year local control, disease-free survival, and overall survival were 44%, 42%, and 52%, respectively. Fifteen patients developed local recurrences; Local control rate was significantly higher with doses >40 Gy EQD2 (52% vs. 34%; p = 0.05). Disease-free survival was better for patients with longer interval (>25 months) between two radiotherapy schedules. Grade III radiation proctitis and cystitis was seen in 3 patients each, and Grade II small bowel toxicity was seen in 3 patients.

CONCLUSIONS

Reirradiation using high-dose-rate brachytherapy is feasible with acceptable outcomes in isolated local recurrence deemed unsuitable for surgery. The outcome is better with higher doses.

A new paradigm to understand and treat diabetic neuropathy

The clinical symptoms of diabetic neuropathy (DN) manifest in a time dependent manner as a positive symptoms (i. e. pain, hypersensitivity, tingling, cramps, cold feet etc.) during its early stages and by a loss of function (i. e. loss of sensory perception, delayed wound healing etc.) predominating in the later stages. Elevated blood glucose alone cannot explain the development and progression of DN and the lowering of blood glucose is insufficient in preventing and/or reversing neuropathy in patients with type 2 diabetes. Recently it has been shown that the endogenous reactive metabolite methylglyoxal (MG) can contribute to the gain of function via post-translational modification in DN of neuronal ion channels involved in chemosensing and action potential generation in nociceptive nerve endings. Dicarbonyls, such as MG, that are elevated in diabetic patients, modify DNA as well as extra- and intracellular proteins, leading to the formation of advanced glycation endproducts (AGEs). Increased formation of AGEs leads to increased cellular stress, dysfunction and ultimately cell death. The interaction of AGE-modified proteins through cell surface receptors, such as RAGE, can lead to increased cellular activation and sustained inflammatory responses, which are the molecular hallmarks of the later, degenerative, stages of DN. The direct and indirect effects of dicarbonyls on nerves or neuronal microvascular network provides a unifying mechanism for the development and progression of DN. Targeting the accumulation of MG and/or prevention of RAGE interactions may therefore provide new, more effective, therapeutic approaches for the treatment of DN.

Peripheral dose measurements with diode and thermoluminescence dosimeters for intensity modulated radiotherapy delivered with conventional and un-conventional linear accelerator

The objective of this paper was to measure the peripheral dose (PD) with diode and thermoluminescence dosimeter (TLD) for intensity modulated radiotherapy (IMRT) with linear accelerator (conventional LINAC), and tomotherapy (novel LINAC). Ten patients each were selected from Trilogy dual-energy and from Hi-Art II tomotherapy. Two diodes were kept at 20 and 25 cm from treatment field edge. TLDs (LiF:MgTi) were also kept at same distance. TLDs were also kept at 5, 10, and 15 cm from field edge. The TLDs were read with REXON reader. The readings at the respective distance were recorded for both diode and TLD. The PD was estimated by taking the ratio of measured dose at the particular distance to the prescription dose. PD was then compared with diode and TLD for LINAC and tomotherapy. Mean PD for LINAC with TLD and diode was 2.52 cGy (SD 0.69), 2.07 cGy (SD 0.88) at 20 cm, respectively, while at 25 cm, it was 1.94 cGy (SD 0.58) and 1.5 cGy (SD 0.75), respectively. Mean PD for tomotherapy with TLD and diode was 1.681 cGy SD 0.53) and 1.58 (SD 0.44) at 20 cm, respectively. The PD was 1.24 cGy (SD 0.42) and 1.088 cGy (SD 0.35) at 25 cm, respectively, for tomotherapy. Overall, PD from tomotherapy was found lower than LINAC by the factor of 1.2-1.5. PD measurement is essential to find out the potential of secondary cancer. PD for both (conventional LINAC) and novel LINACs (tomotherapy) were measured and compared with each other. The comparison of the values for PD presented in this work and those published in the literature is difficult because of the different experimental conditions. The diode and TLD readings were reproducible and both the detector readings were comparable.

Dosimetric validation of new semiconductor diode dosimetry system for intensity modulated radiotherapy

INTRODUCTION

The new diode Isorad was validated for intensity modulated radiotherapy (IMRT) and the observations during the validation are reported.

MATERIALS AND METHODS

The validation includes intrinsic precision, post-irradiation stability, dose linearity, dose-rate effect, angular response, source to surface (SSD) dependence, field size dependence, and dose calibration.

RESULTS

The intrinsic precision of the diode was more than 1% (1 σ). The linearity found in the whole range of dose analyzed was 1.93% (R² = 1). The minimum and maximum variation in the measured and calculated dose were found to be 0.78% (with 25 MU at ioscentre) and 4.8% (with 1000 MU at isocentre), respectively. The maximal variation in angular response with respect to arbitrary angle 0° found was 1.31%. The diode exhibited a 51.7% and 35% decrease in the response in the 35 cm and 20 cm SSD range, respectively. The minimum and the maximum variation in the measured dose from the diode and calculated dose were 0.82% (5 cm × 5 cm) and 3.75% (30 cm × 30 cm), respectively. At couch 270°, the response of the diode was found to vary maximum by 1.4% with ± 60 gantry angle. Mean variation between measured dose with diode and planned dose by TPS was found to be 1.3% (SD 0.75) for IMRT patient-specific quality assurance.

CONCLUSION

For the evaluation of IMRT, use of cylindrical diode is strongly recommended.

Additional rectal and sigmoid mucosal points and doses in high dose rate intracavitary brachytherapy for carcinoma cervix: a dosimetric study

BACKGROUND

Late rectal and sigmoid toxicities seen in cervical cancer patients are attributed to brachytherapy despite rectal doses within tolerance limits. The purpose of this study was to identify additional dosimetric points which may better forecast rectal complications.

MATERIALS AND METHODS

Fifteen high dose rate intracavitary brachytherapy (ICA-HDR) applications with conventional X-ray and computed tomography (CT) based planning were studied. In addition to International Commission on Radiation Units and Measurement (ICRU) rectal and bladder points, proximal and distal rectal and sigmoid points were digitized on CT scans and dose volume histograms' (DVHs') parameters were computed and correlated.

RESULTS

The mean ICRU, additional distal, proximal and sigmoid point doses were 486 ± 152 cGy, 527 ± 156 cGy, 401 ± 149 cGy and 838 ± 254 cGy, respectively, for a prescription of 700 cGy to point A. The mean sigmoid point dose was significantly higher than the ICRU rectal point doses (P=0.001). The high-dose sigmoid points were situated at a mean -8 mm (range -22.95 to 10.43 mm) lateral, 10 mm posterior (range -15.87 to 27.82 mm) and 31 mm (range 8.08-62.91 mm) cranial to the intracavitary applicator flange of central tandem.

CONCLUSIONS

Our dosimetric study suggests that sigmoid points and 0.1 cm 3 receive significantly higher doses than rectal points during ICA-HDR in carcinoma of the uterine cervix. No definite conclusion on reproducible spatial distribution on orthogonal X-rays could be achieved. To document and reduce sigmoid doses, some form of 3D image-based planning is necessary.

Whole-body PET acceptance test in 2D and 3D using NEMA NU 2-2001 protocol

Integrated PET/CT has emerged as an integral component of oncology management because of its unique potential of providing both functional and morphological images in a single imaging session. In this work, performance of the ‘bismuth germinate (BGO) crystal’-based PET of a newly installed Discovery ST PET/CT was evaluated in 2D and 3D mode for whole-body scanning using National Electrical Manufacturers Association (NEMA) NU 2-2001 protocol and the recommended phantoms. During the entire measurements, the system operates with an energy window of 375-650 keV and 11.7 ns coincidence time window. The set of tests performed were spatial resolution, sensitivity, scatter fraction (SF) and counting rate performance. The average transaxial and axial spatial resolution measured as full width at half maximum (FWHM) of the point spread function at 1 cm (and 10 cm) off-axis was 0.632 (0.691) and 0.491 (0.653) cm in 2D and 0.646 (0.682) and 0.54 (0.601) cm in 3D respectively. The average sensitivity for the two radial positions (R = 0 cm and R = 10 cm) was 2.56 (2.63) cps/kBq in 2D and 11.85 (12.14) cps/kBq in 3D. The average scatter fraction was 19.79% in 2D and 46.19% in 3D. The peak noise equivalent counting rate (NECR) evaluated with single random subtraction was 89.41 kcps at 49 kBq/cc in 2D and 60 kcps at 12 kBq/cc in 3D acquisition mode. The NECR with delayed random subtraction was 61.47 kcps at 40.67 kBq/cc in 2D and 45.57 kcps at 16.45 kBq/cc in 3D. The performance of the PET scanner was satisfactory within the manufacturer-specified limits. The test result of PET shows excellent system sensitivity with relatively uniform resolution throughout the FOV, making this scanner highly suitable for whole-body studies.

Whole abdomen radiation therapy in ovarian cancers: a comparison between fixed beam and volumetric arc based intensity modulation

Purpose

A study was performed to assess dosimetric characteristics of volumetric modulated arcs (RapidArc, RA) and fixed field intensity modulated therapy (IMRT) for Whole Abdomen Radiotherapy (WAR) after ovarian cancer.

Methods and Materials

Plans for IMRT and RA were optimised for 5 patients prescribing 25 Gy to the whole abdomen (PTV_WAR) and 45 Gy to the pelvis and pelvic nodes (PTV_Pelvis) with Simultaneous Integrated Boost (SIB) technique. Plans were investigated for 6 MV (RA6, IMRT6) and 15 MV (RA15, IMRT15) photons. Objectives were: for both PTVs V_90% > 95%, for PTV_Pelvis: D_max < 105%; for organs at risk, maximal sparing was required. The MU and delivery time measured treatment efficiency. Pre-treatment Quality assurance was scored with Gamma Agreement Index (GAI) with 3% and 3 mm thresholds.

Results

IMRT and RapidArc resulted comparable for target coverage. For PTV_WAR, V_90% was 99.8 ± 0.2% and 93.4 ± 7.3% for IMRT6 and IMRT15, and 98.4 ± 1.7 and 98.6 ± 0.9% for RA6 and RA15. Target coverage resulted improved for PTV_Pelvis. Dose homogeneity resulted slightly improved by RA (Uniformity was defined as U_5-95% = D_5%-D_95%/D_mean). U₅-_95% for PTV_WAR was 0.34 ± 0.05 and 0.32 ± 0.06 (IMRT6 and IMRT15), 0.30 ± 0.03 and 0.26 ± 0.04 (RA6 and RA15); for PTV_Pelvis, it resulted equal to 0.1 for all techniques. For organs at risk, small differences were observed between the techniques. MU resulted 3130 ± 221 (IMRT6), 2841 ± 318 (IMRT15), 538 ± 29 (RA6), 635 ± 139 (RA15); the average measured treatment time was 18.0 ± 0.8 and 17.4 ± 2.2 minutes (IMRT6 and IMRT15) and 4.8 ± 0.2 (RA6 and RA15). GAI_IMRT6 = 97.3 ± 2.6%, GAI_IMRT15 = 94.4 ± 2.1%, GAI_RA6 = 98.7 ± 1.0% and GAI_RA15 = 95.7 ± 3.7%.

Conclusion

RapidArc showed to be a solution to WAR treatments offering good dosimetric features with significant logistic improvements compared to IMRT.

Radiation therapy with implanted cardiac pacemaker devices: a clinical and dosimetric analysis of patients and proposed precautions

AIMS

To report the radiation planning dosimetric aspects and clinical outcomes of patients with implanted cardiac pacemakers.

MATERIALS AND METHODS

Between 2005 and 2009, eight patients with in situ cardiac pacemakers of varied primary site were treated at our hospital. All patients underwent computed tomography-based treatment planning. The target volumes, organs at risk and pacemaker device were all contoured. A treatment plan optimally covering the target area and maximally sparing the pacemaker was generated. All patients were evaluated at baseline, during radiotherapy and after radiotherapy conclusion by a cardiologist as well as pacemaker company personnel.

RESULTS

The median age at presentation was 67 (range 53-77) years. There were three men with head and neck primaries, two men with lung primaries and three women with breast primaries. The prescribed dose ranged from 45 to 70 Gy in 25-35 fractions with a daily dose of 1.8-2.0 Gy. Four patients had the pacemaker implanted on the same side as the radiotherapy target. The dose ranges for the minimum, mean and maximum doses to the pacemaker were 0.06-2.0, 0.07-20.6 and 0.14-60.0 Gy, respectively. Radiation therapy was safely delivered in all patients without any untoward effects. At 5 months of median follow-up, all patients were well with no malfunction of the pacemaker.

CONCLUSION

A series of eight patients with in situ pacemakers treated with radiotherapy is reported. Radiotherapy can be safely delivered in patients with implanted cardiac pacemakers. However, it mandates a cautious approach in planning and treatment delivery to ensure the least possible dose to the pacemaker. Close liaison with the cardiologist and a pacemaker clinic before, during and after the course of treatment is essential to ensure patient safety.

Factors influencing neurocognitive outcomes in young patients with benign and low-grade brain tumors treated with stereotactic conformal radiotherapy

PURPOSE

To present the effect of radiotherapy doses to different volumes of normal structures on neurocognitive outcomes in young patients with benign and low-grade brain tumors treated prospectively with stereotactic conformal radiotherapy (SCRT).

METHODS AND MATERIALS

Twenty-eight patients (median age, 13 years) with residual/progressive brain tumors (10 craniopharyngioma, 8 cerebellar astrocytoma, 6 optic pathway glioma and 4 cerebral low-grade glioma) were treated with SCRT to a dose of 54 Gy in 30 fractions over 6 weeks. Prospective neuropsychological assessments were done at baseline before RT and at subsequent follow-up examinations. The change in intelligence quotient (IQ) scores was correlated with various factors, including dose-volume to normal structures.

RESULTS

Although the overall mean full-scale IQ (FSIQ) at baseline before RT remained unchanged at 2-year follow-up after SCRT, one third of patients did show a >10% decline in FSIQ as compared with baseline. Logistic regression analysis demonstrated that patients aged <15 years had a significantly higher chance of developing a >10% drop in FSIQ than older patients (53% vs. 10%, p = 0.03). Dosimetric comparison in patients showing a >10% decline vs. patients showing a <10% decline in IQ revealed that patients receiving >43.2 Gy to >13% of volume of the left temporal lobe were the ones to show a significant drop in FSIQ (p = 0.048). Radiotherapy doses to other normal structures, including supratentorial brain, right temporal lobe, and frontal lobes, did not reveal any significant correlation.

CONCLUSION

Our prospectively collected dosimetric data show younger age and radiotherapy doses to left temporal lobe to be predictors of neurocognitive decline, and may well be used as possible dose constraints for high-precision radiotherapy planning.