This publication is based on sources and information believed to be reliable, but the AAPM, the e... more This publication is based on sources and information believed to be reliable, but the AAPM, the editors, and the publisher disclaim any warranty or liability based on or relating to the contents of this publication. The AAPM does not endorse any products, manufacturers, or suppliers. Nothing in this publication should be interpreted as implying such endorsement.
serving on my supervisory committee and their encouraging support. I am grateful to my current em... more serving on my supervisory committee and their encouraging support. I am grateful to my current employer H. Lee Moffitt Cancer Center & Research Institute for providing me the time, support, and resources for this work. I would like to thank Jie Shi from Sun Nuclear Corporation for his in depth critiques and many helpful comments on temperature and dose rate studies. Thanks to Bill Simon and Jie Shi of Sun Nuclear Corporation, Bill Zimmermann of Fluke biomedical, and Camilla Rönnqvist of Scanditronix Wellhöfer for providing the diodes used in this study. Above all, I can not thank enough my uncle Daljit Saini who has provided guidance, support, and encouragement throughout my undergraduate and graduate studies.
Abstract The Halcyon™ platform is self‐contained, combining a treatment planning (Eclipse) system... more Abstract The Halcyon™ platform is self‐contained, combining a treatment planning (Eclipse) system TPS) with information management and radiation delivery components. The standard TPS beam model is configured and locked down by the vendor. A portal dosimetry‐based system for patient‐specific QA (PSQA) is also included. While ensuring consistency across the user base, this closed model may not be optimal for every department. We set out to commission independent TPS (RayStation 9B, RaySearch Laboratories) and PSQA (PerFraction, Sun Nuclear Corp.) systems for use with the Halcyon linac. The output factors and PDDs for very small fields (0.5 × 0.5 cm2) were collected to augment the standard Varian dataset. The MLC leaf‐end parameters were estimated based on the various static and dynamic tests with simple model fields and honed by minimizing the mean and standard deviation of dose difference between the ion chamber measurements and RayStation Monte Carlo calculations for 15 VMAT and IMRT test plans. Two chamber measurements were taken per plan, in the high (isocenter) and lower dose regions. The ratio of low to high doses ranged from 0.4 to 0.8. All percent dose differences were expressed relative to the local dose. The mean error was 0.0 ± 1.1% (TG119‐style confidence limit ± 2%). Gamma analysis with the helical diode array using the standard 3%Global/2mm criteria resulted in the average passing rate of 99.3 ± 0.5% (confidence limit 98.3%–100%). The average local dose error for all detectors across all plans was 0.2% ± 5.3%. The ion chamber results compared favorably with our recalculation with Eclipse and PerFraction, as well as with several published Eclipse reports. Dose distribution gamma analysis comparisons between RayStation and PerFraction with 2%Local/2mm criteria yielded an average passing rate of 98.5% ± 0.8% (confidence limit 96.9%–100%). It is feasible to use the Halcyon accelerator with independent planning and verification systems without sacrificing dosimetric accuracy.
International Journal of Radiation Oncology*Biology*Physics, 2014
Background and purpose: We sought to analyze the effect of polyethylene glycol (PEG) hydrogel on ... more Background and purpose: We sought to analyze the effect of polyethylene glycol (PEG) hydrogel on rectal doses in prostate cancer patients undergoing radiotherapy. Materials and methods: Between July 2009 and April 2013, we treated 200 clinically localized prostate cancer patients with high-dose rate (HDR) brachytherapy ± intensity modulated radiation therapy. Half of the patients received a transrectal ultrasound (TRUS)-guided transperineal injection of 10 mL PEG hydrogel (DuraSeal™ Spinal Sealant System; Covidien, Mansfield, MA) in their anterior perirectal fat immediately prior to the first HDR brachytherapy treatment and 5 mL PEG hydrogel prior to the second HDR brachytherapy treatment. Prostate, rectal, and bladder doses and prostate-rectal distances were calculated based upon treatment planning CT scans. Results: There was a success rate of 100% (100/100) with PEG hydrogel implantation. PEG hydrogel significantly increased the prostate-rectal separation (mean ± SD, 12 ± 4 mm with gel vs. 4 ± 2 mm without gel, p < 0.001) and significantly decreased the mean rectal D 2 mL (47 ± 9% with gel vs. 60 ± 8% without gel, p < 0.001). Gel decreased rectal doses regardless of body mass index (BMI). Conclusions: PEG hydrogel temporarily displaced the rectum away from the prostate by an average of 12 mm and led to a significant reduction in rectal radiation doses, regardless of BMI.
Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were exami... more Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were examined with respect to glutathione peroxidase (GSH-Px) activity and reduced glutathione (GSH) contents. The activity of GSH-Px and GSH content were found to be lower in RBC from CRF patients as compared with normal RBC. These reduced levels of GSH and GSH-Px in the red cells of uraemic patients rnaypredispose the cells to oxidative damage.
Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were exami... more Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were examined with respect to glutathione peroxidase (GSH-Px) activity and reduced glutathione (GSH) contents. The activity of GSH-Px and GSH content were found to be lower in RBC from CRF patients as compared with normal RBC. These reduced levels of GSH and GSH-Px in the red cells of uraemic patients may predispose the cells to oxidative damage.
The energy dependence of commercially available diode detectors was measured for nominal accelera... more The energy dependence of commercially available diode detectors was measured for nominal accelerating potential ranging between Co-60 and 17 MV. The measurements were performed in a liquid water phantom at 5 cm depth for 10 x 10 cm2 collimator setting and source-to-detector distance of 100 cm. The response (nC/Gy) was normalized to Co-60 beam after corrections for the dose rate and temperature dependences for each diode. The energy dependence, calculated by taking the percent difference between the maximum and minimum sensitivity normalized to Co-60 beam, varied by 39% for the n-type Isorad Red, 26% for the n-type Isorad Electron, 19% for the QED Red (p-type), 15% for the QED Electron (p-type), 11% for the QED Blue (p-type), and 6% for the EDP10 diode for nominal accelerating potential between Co-60 and 17 MV. It varied by 34% for the Isorad-3 Gold #1 and #2, 35% for the Veridose Green, 15% for the Veridose Yellow, 9% for the Veridose Electron, 21% for the n-type QED Gold, 24% for the n-type QED Red, 3% for the EDP23G, 2% for the PFD (photon field detector), 7% for the EDP103G, and 16% for the EDP203G for nominal accelerating potential between Co-60 and 15 MV. The magnitude of the energy dependence is verified by Monte Carlo simulation. We concluded that the energy dependence does not depend on whether the diode is n- or p-type but rather depends mainly on the material around the die such as the buildup and the geometry of the buildup material. As a result, the value of the energy dependence can vary for each individual diode depending on the actual geometry and should be used with caution.
The dose-rate dependence of commercially available diode detectors was measured under both high i... more The dose-rate dependence of commercially available diode detectors was measured under both high instantaneous dose-rate (pulsed) and low dose rate (continuous, Co-60) radiation. The dose-rate dependence was measured in an acrylic miniphantom at a 5-cm depth in a 10 x 10 cm2 collimator setting, by varying source-to-detector distance (SDD) between at least 80 and 200 cm. The ratio of a normalized diode reading to a normalized ion chamber reading (both at SDD=100 cm) was used to determine diode sensitivity ratio for pulsed and continuous radiation at different SDD. The inverse of the diode sensitivity ratio is defined as the SDD correction factor (SDD CF). The diode sensitivity ratio increased with increasing instantaneous dose rate (or decreasing SDD). The ratio of diode sensitivity, normalized to 4000 cGy/s, varied between 0.988 (1490 cGy/s)-1.023 (38,900 cGy/s) for unirradiated n-type Isorad Gold, 0.981 (1460 cGy/s)-1.026 (39,060 cGy/s) for unirradiated QED Red (n type), 0.972 (1490 cGy/s)-1.068 (38,900 cGy/s) for preirradiated Isorad Red (n type), 0.985 (1490 cGy/s)-1.012 (38,990 cGy/s) for n-type Pt-doped Isorad-3 Gold, 0.995 (1450 cGy/s)-1.020 (21,870 cGy/s) for n-type Veridose Green, 0.978 (1450 cGy/s)-1.066 (21,870 cGy/s) for preirradiated Isorad-p Red, 0.994 (1540 cGy/s)-1.028 (17,870 cGy/s) for p-type preirradiated QED, 0.998 (1450 cGy/s)-1.003 (21,870 cGy/s) for the p-type preirradiated Scanditronix EDP20(3G), and 0.998 (1490 cGy/s)-1.015 (38,880 cGy/s) for Scanditronix EDP10(3G) diodes. The p-type diodes do not always show less dose-rate dependence than the n-type diodes. Preirradiation does not always reduce diode dose-rate dependence. A comparison between the SDD dependence measured at the surface of a full scatter phantom and that in a miniphantom was made. Using a direct adjustment of radiation pulse height, we concluded that the SDD dependence of diode sensitivity can be explained by the instantaneous dose-rate dependence if sufficient buildup is provided to eliminate electron contamination. An energy independent empirical formula was proposed to fit the dose-rate dependence of diode sensitivity.
Temperature dependence of commercially available n- and p-type diodes were studied experimentally... more Temperature dependence of commercially available n- and p-type diodes were studied experimentally under both high instantaneous dose rate (pulsed) and low dose rate (continuous) radiation. The sensitivity versus temperature was measured at SSD = 80 or 100 cm, 10 x 10 cm2, and 5 cm depth in a 30 x 30 x 30 cm3 water phantom between 10 degrees C and 35 degrees C. The response was linear for all the diode detectors. The temperature coefficient (or sensitivity variation with temperature, svwt) was dose rate independent for preirradiated diodes. They were (0.30 +/- 0.01)%/degrees C, (0.36 +/- 0.03)%/degrees C, and (0.29 +/- 0.08)%/degrees C for QED p-type, EDP p-type, and Isorad n-type diodes, respectively. The temperature coefficient for unirradiated n-type diodes was different under low dose rate [(0.16 to 0.45)%/degrees C, continuous, cobalt] and high instantaneous dose rate [(0.07 +/- 0.02)%/degrees C, pulsed radiation]. Moreover, the temperature coefficient varies among individual diodes. Similarly, the temperature coefficient for a special unirradiated QED p-type diode was different under low dose rate (0.34%/degrees C, cobalt) and high instantaneous dose rate [(0.26 +/- 0.01)%/degrees C, pulsed radiation]. Sufficient preirradiation can eliminate dose rate dependence of the temperature coefficient. On the contrary, preirradiation cannot eliminate dose rate dependence of the diode sensitivity itself.
To evaluate the use of high-dose-rate (HDR) brachytherapy ± intensity modulated radiation therapy... more To evaluate the use of high-dose-rate (HDR) brachytherapy ± intensity modulated radiation therapy (IMRT) as salvage therapy for patients with an isolated, gross local recurrence of prostate cancer after radical prostatectomy. Between October 2009 and May 2013, the authors treated six patients with salvage iridium-192 HDR brachytherapy ± IMRT for biopsy-proven, recurrent prostate cancer post-prostatectomy. In each patient, a pelvic MRI scan or CT scan demonstrated a nodule (range 1.6, 4.7 cm) in the prostate bed. Although prostate-specific antigen values were 0.2-9.5 ng/mL at the time of salvage brachytherapy, there was no pelvic adenopathy on CT or MRI scan, and a bone scan was negative in all cases. Five patients were treated with IMRT to 4500-5040 cGy in 25-28 fractions to the prostate bed followed by two 950 cGy HDR brachytherapy fractions separated by 1-2 weeks. A sixth patient underwent HDR brachytherapy monotherapy consisting of 3800 cGy in four fractions over 3 days. Toxicities were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. Median followup was 9 months (range 3, 40 months). All six patients have been free of androgen deprivation therapy and have an undetectable prostate-specific antigen. One patient developed late Grade 2 urinary incontinence. There was no late grade ≥2 gastrointestinal toxicity. HDR brachytherapy ± IMRT is a safe and effective salvage therapy option for an isolated, gross local recurrence of prostate cancer after radical prostatectomy and merits further study.
Purpose: To report acute (!3 months) and late (O6 months) genitourinary (GU), and gastrointestina... more Purpose: To report acute (!3 months) and late (O6 months) genitourinary (GU), and gastrointestinal (GI) toxicities, and erectile dysfunction (ED) in patients treated with inverse-planned selective HDR brachytherapy boost to the dominant intraprostatic lesion (DIL) defined with magnetic resonance spectroscopy (MRS). Materials and Methods: We analyzed data prospectively collected from 20 patients treated in 2010-2011 for localized intermediate-risk prostate adenocarcinoma. All patients had an MRI/MRS to define the DIL before treatment. Afterward, they received external beam pelvic radiation (40-44 Gy in 20-22 fractions) followed by HDR ( 192 Ir) brachytherapy boost. The boost dose was 15 Gy in one fraction to the whole gland with simultaneous 3 Gy selective boost to the DIL (total of 18 Gy to DIL). All patients were planned with inverse-planning simulated annealing (IPSA). Thereafter, IPSS, International Index of Erectile Dysfunction-5 (IIEF5) and GI toxicities questionnaires were completed prospectively every three months at a followup visits. Results: The median age was 65.5 years. The median followup was 23.6 months. Fifty-five percent of the patients had clinical stage T1c, 25 % T2a, 15% T2b and 5% T2c. All patients were Gleason score (GS) 7. The pretreatment PSA was 0-5 ng/mL in 30%, 5-10 ng/mL in 60% and 10-15 ng/mL in 10% of the patients, respectively. No patients received antiandrogen therapy. The average IPSS at baseline and 1, 4 and 12 months was 6.57/35, 10.94/35, 7.32/35 and 8.47/35, respectively. At 3 months we observed a decrease of IIEF5 score from baseline of -4.45 (þ/-0.22) and -3.31 (þ/-0.39) at O6 months. At 3 months 50% of patients presented no GI symptoms and 50% occasional GI symptoms. No patients presented severe GI toxicity O6 months. Conclusions: Selective DIL image-guided (MRS) HDR brachytherapy boost in intermediate-risk cancer, is feasible with acceptable acute and late GU and GI toxicity at the price of decreasing IIEF5 score. Longer followup is necessary to evaluate tumor control.
Preoperative high-dose-rate (HDR) endorectal brachytherapy is well tolerated among patients with ... more Preoperative high-dose-rate (HDR) endorectal brachytherapy is well tolerated among patients with locally advanced rectal cancer. However, these studies excluded patients who previously received pelvic radiation therapy (RT). Because a favorable toxicity profile has been published for HDR endorectal brachytherapy, we evaluated this technique in patients who have previously received pelvic irradiation. We included patients who had received pelvic irradiation for a previous pelvic malignancy and later received preoperative HDR endorectal brachytherapy for rectal cancer. Brachytherapy was delivered to a total dose of 26 Gy in 4 consecutive daily 6.5 Gy fractions. We evaluated 10 patients who previously received pelvic external beam radiation therapy (EBRT) alone (n=6), EBRT and brachytherapy (n=2), or brachytherapy alone (n=2). The median interval between the initial course of RT and endorectal brachytherapy was approximately 11 years (range, 1-19 years). Two patients experienced a complete pathologic response while 1 patient had a near complete pathologic response. No acute grade ≥3 toxicity was observed. No intraoperative or postoperative surgical complications were observed. Preoperative HDR endorectal brachytherapy is an alternative to EBRT for patients with locally advanced rectal cancer who have previously received pelvic RT.
The myotoxic growth factor: a novel role of IGF-I in skeletal myoblasts? ... Institute for Biophy... more The myotoxic growth factor: a novel role of IGF-I in skeletal myoblasts? ... Institute for Biophysical and Clinical Research into Human Movement, Stoke-On-Trent, Cheshire, UK. ... Introduction: Prolonged elevations of proinflammatory cytokines are associated with ...
Prior studies illustrated a reduction in wound complications with the use of staged reconstructio... more Prior studies illustrated a reduction in wound complications with the use of staged reconstruction (SR) and negative pressure wound therapy when treating soft tissue sarcoma (STS) with surgical resection followed by high-dose-rate adjuvant brachytherapy. The purpose of this study is to compare the outcomes of SR and immediate reconstruction (IR) brachytherapy in recurrent STS. A retrospective review of 40 patients with recurrent STS of the local extremity and trunk treated with resection followed by adjuvant brachytherapy alone. Margin status was defined as positive (SM(+)) if there was microscopic involvement (R1) or ≤1 mm margin and negative (SM(-)) if >1 mm margin was obtained. SR and IR were compared regarding toxicity, local control, and limb preservation. Median followup was 27 months. When comparing the SR (n = 22) and IR (n = 18) cohorts, there was a significantly lower final SM(+) rate in SR (32% vs. 83%, p < 0.01). A 2-year local control benefit seen with SR (80% vs....
Journal of Biomolecular Techniques Jbt, Jul 1, 2009
Quantitative RT-PCR can be carried out as a one-or a two-step reaction. However, the choice of me... more Quantitative RT-PCR can be carried out as a one-or a two-step reaction. However, the choice of method raises controversy from the perspective of the researcher and manufacturer, because of advantages and disadvantages with both systems. We therefore hypothesize that running the RNA-to-C T ™ 2-Step kit [(Applied Biosystems (AB), Foster City, CA] using a one-step protocol (as recommended) is not appropriate for quantitation of gene expression levels and should not be performed. Consequently, we ran comparative studies of the two suggested methods to evaluate their efficiency, sensitivity, and accuracy. To ensure precession, two different PCR machines were used: the StepOnePlus system and Chromo4. In addition, the RNA-to-C T ™ 1-Step kit (recently launched by AB) was also used to compare its efficiency with these methods. Efficiency, sensitivity, and linearity were determined by standard curves generated using RNA isolated from C2 myoblasts to amplify the housekeeping gene GAPDH. When the RNA-to-C T ™ 2-Step kit was run as a two-step reaction on the Chromo4 or StepOnePlus, respectively, not only did the efficiency increase (100Ϯ1.5% and 99.7Ϯ0.95%) but also the sensitivity (comparative threshold cycle for the lowest standard: 33.2Ϯ0.5 and 32.5Ϯ0.7) and linearity (0.997Ϯ0.001 and 0.993Ϯ0.006) compared with RNA-to-C T ™ 2-Step run as one-step and RNA-to-C T ™ 1-Step kit. This is the first study to demonstrate that the RNA-to-C T ™ 2-Step kit is not reliable to be performed as a one-step reaction but as a two-step reaction, is even more sensitive than the newly launched RNA-to-C T ™ 1-Step kit.
This publication is based on sources and information believed to be reliable, but the AAPM, the e... more This publication is based on sources and information believed to be reliable, but the AAPM, the editors, and the publisher disclaim any warranty or liability based on or relating to the contents of this publication. The AAPM does not endorse any products, manufacturers, or suppliers. Nothing in this publication should be interpreted as implying such endorsement.
serving on my supervisory committee and their encouraging support. I am grateful to my current em... more serving on my supervisory committee and their encouraging support. I am grateful to my current employer H. Lee Moffitt Cancer Center & Research Institute for providing me the time, support, and resources for this work. I would like to thank Jie Shi from Sun Nuclear Corporation for his in depth critiques and many helpful comments on temperature and dose rate studies. Thanks to Bill Simon and Jie Shi of Sun Nuclear Corporation, Bill Zimmermann of Fluke biomedical, and Camilla Rönnqvist of Scanditronix Wellhöfer for providing the diodes used in this study. Above all, I can not thank enough my uncle Daljit Saini who has provided guidance, support, and encouragement throughout my undergraduate and graduate studies.
Abstract The Halcyon™ platform is self‐contained, combining a treatment planning (Eclipse) system... more Abstract The Halcyon™ platform is self‐contained, combining a treatment planning (Eclipse) system TPS) with information management and radiation delivery components. The standard TPS beam model is configured and locked down by the vendor. A portal dosimetry‐based system for patient‐specific QA (PSQA) is also included. While ensuring consistency across the user base, this closed model may not be optimal for every department. We set out to commission independent TPS (RayStation 9B, RaySearch Laboratories) and PSQA (PerFraction, Sun Nuclear Corp.) systems for use with the Halcyon linac. The output factors and PDDs for very small fields (0.5 × 0.5 cm2) were collected to augment the standard Varian dataset. The MLC leaf‐end parameters were estimated based on the various static and dynamic tests with simple model fields and honed by minimizing the mean and standard deviation of dose difference between the ion chamber measurements and RayStation Monte Carlo calculations for 15 VMAT and IMRT test plans. Two chamber measurements were taken per plan, in the high (isocenter) and lower dose regions. The ratio of low to high doses ranged from 0.4 to 0.8. All percent dose differences were expressed relative to the local dose. The mean error was 0.0 ± 1.1% (TG119‐style confidence limit ± 2%). Gamma analysis with the helical diode array using the standard 3%Global/2mm criteria resulted in the average passing rate of 99.3 ± 0.5% (confidence limit 98.3%–100%). The average local dose error for all detectors across all plans was 0.2% ± 5.3%. The ion chamber results compared favorably with our recalculation with Eclipse and PerFraction, as well as with several published Eclipse reports. Dose distribution gamma analysis comparisons between RayStation and PerFraction with 2%Local/2mm criteria yielded an average passing rate of 98.5% ± 0.8% (confidence limit 96.9%–100%). It is feasible to use the Halcyon accelerator with independent planning and verification systems without sacrificing dosimetric accuracy.
International Journal of Radiation Oncology*Biology*Physics, 2014
Background and purpose: We sought to analyze the effect of polyethylene glycol (PEG) hydrogel on ... more Background and purpose: We sought to analyze the effect of polyethylene glycol (PEG) hydrogel on rectal doses in prostate cancer patients undergoing radiotherapy. Materials and methods: Between July 2009 and April 2013, we treated 200 clinically localized prostate cancer patients with high-dose rate (HDR) brachytherapy ± intensity modulated radiation therapy. Half of the patients received a transrectal ultrasound (TRUS)-guided transperineal injection of 10 mL PEG hydrogel (DuraSeal™ Spinal Sealant System; Covidien, Mansfield, MA) in their anterior perirectal fat immediately prior to the first HDR brachytherapy treatment and 5 mL PEG hydrogel prior to the second HDR brachytherapy treatment. Prostate, rectal, and bladder doses and prostate-rectal distances were calculated based upon treatment planning CT scans. Results: There was a success rate of 100% (100/100) with PEG hydrogel implantation. PEG hydrogel significantly increased the prostate-rectal separation (mean ± SD, 12 ± 4 mm with gel vs. 4 ± 2 mm without gel, p < 0.001) and significantly decreased the mean rectal D 2 mL (47 ± 9% with gel vs. 60 ± 8% without gel, p < 0.001). Gel decreased rectal doses regardless of body mass index (BMI). Conclusions: PEG hydrogel temporarily displaced the rectum away from the prostate by an average of 12 mm and led to a significant reduction in rectal radiation doses, regardless of BMI.
Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were exami... more Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were examined with respect to glutathione peroxidase (GSH-Px) activity and reduced glutathione (GSH) contents. The activity of GSH-Px and GSH content were found to be lower in RBC from CRF patients as compared with normal RBC. These reduced levels of GSH and GSH-Px in the red cells of uraemic patients rnaypredispose the cells to oxidative damage.
Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were exami... more Erythrocytes from 18 patients with chronic renal failure (CRF) and 10 healthy subjects were examined with respect to glutathione peroxidase (GSH-Px) activity and reduced glutathione (GSH) contents. The activity of GSH-Px and GSH content were found to be lower in RBC from CRF patients as compared with normal RBC. These reduced levels of GSH and GSH-Px in the red cells of uraemic patients may predispose the cells to oxidative damage.
The energy dependence of commercially available diode detectors was measured for nominal accelera... more The energy dependence of commercially available diode detectors was measured for nominal accelerating potential ranging between Co-60 and 17 MV. The measurements were performed in a liquid water phantom at 5 cm depth for 10 x 10 cm2 collimator setting and source-to-detector distance of 100 cm. The response (nC/Gy) was normalized to Co-60 beam after corrections for the dose rate and temperature dependences for each diode. The energy dependence, calculated by taking the percent difference between the maximum and minimum sensitivity normalized to Co-60 beam, varied by 39% for the n-type Isorad Red, 26% for the n-type Isorad Electron, 19% for the QED Red (p-type), 15% for the QED Electron (p-type), 11% for the QED Blue (p-type), and 6% for the EDP10 diode for nominal accelerating potential between Co-60 and 17 MV. It varied by 34% for the Isorad-3 Gold #1 and #2, 35% for the Veridose Green, 15% for the Veridose Yellow, 9% for the Veridose Electron, 21% for the n-type QED Gold, 24% for the n-type QED Red, 3% for the EDP23G, 2% for the PFD (photon field detector), 7% for the EDP103G, and 16% for the EDP203G for nominal accelerating potential between Co-60 and 15 MV. The magnitude of the energy dependence is verified by Monte Carlo simulation. We concluded that the energy dependence does not depend on whether the diode is n- or p-type but rather depends mainly on the material around the die such as the buildup and the geometry of the buildup material. As a result, the value of the energy dependence can vary for each individual diode depending on the actual geometry and should be used with caution.
The dose-rate dependence of commercially available diode detectors was measured under both high i... more The dose-rate dependence of commercially available diode detectors was measured under both high instantaneous dose-rate (pulsed) and low dose rate (continuous, Co-60) radiation. The dose-rate dependence was measured in an acrylic miniphantom at a 5-cm depth in a 10 x 10 cm2 collimator setting, by varying source-to-detector distance (SDD) between at least 80 and 200 cm. The ratio of a normalized diode reading to a normalized ion chamber reading (both at SDD=100 cm) was used to determine diode sensitivity ratio for pulsed and continuous radiation at different SDD. The inverse of the diode sensitivity ratio is defined as the SDD correction factor (SDD CF). The diode sensitivity ratio increased with increasing instantaneous dose rate (or decreasing SDD). The ratio of diode sensitivity, normalized to 4000 cGy/s, varied between 0.988 (1490 cGy/s)-1.023 (38,900 cGy/s) for unirradiated n-type Isorad Gold, 0.981 (1460 cGy/s)-1.026 (39,060 cGy/s) for unirradiated QED Red (n type), 0.972 (1490 cGy/s)-1.068 (38,900 cGy/s) for preirradiated Isorad Red (n type), 0.985 (1490 cGy/s)-1.012 (38,990 cGy/s) for n-type Pt-doped Isorad-3 Gold, 0.995 (1450 cGy/s)-1.020 (21,870 cGy/s) for n-type Veridose Green, 0.978 (1450 cGy/s)-1.066 (21,870 cGy/s) for preirradiated Isorad-p Red, 0.994 (1540 cGy/s)-1.028 (17,870 cGy/s) for p-type preirradiated QED, 0.998 (1450 cGy/s)-1.003 (21,870 cGy/s) for the p-type preirradiated Scanditronix EDP20(3G), and 0.998 (1490 cGy/s)-1.015 (38,880 cGy/s) for Scanditronix EDP10(3G) diodes. The p-type diodes do not always show less dose-rate dependence than the n-type diodes. Preirradiation does not always reduce diode dose-rate dependence. A comparison between the SDD dependence measured at the surface of a full scatter phantom and that in a miniphantom was made. Using a direct adjustment of radiation pulse height, we concluded that the SDD dependence of diode sensitivity can be explained by the instantaneous dose-rate dependence if sufficient buildup is provided to eliminate electron contamination. An energy independent empirical formula was proposed to fit the dose-rate dependence of diode sensitivity.
Temperature dependence of commercially available n- and p-type diodes were studied experimentally... more Temperature dependence of commercially available n- and p-type diodes were studied experimentally under both high instantaneous dose rate (pulsed) and low dose rate (continuous) radiation. The sensitivity versus temperature was measured at SSD = 80 or 100 cm, 10 x 10 cm2, and 5 cm depth in a 30 x 30 x 30 cm3 water phantom between 10 degrees C and 35 degrees C. The response was linear for all the diode detectors. The temperature coefficient (or sensitivity variation with temperature, svwt) was dose rate independent for preirradiated diodes. They were (0.30 +/- 0.01)%/degrees C, (0.36 +/- 0.03)%/degrees C, and (0.29 +/- 0.08)%/degrees C for QED p-type, EDP p-type, and Isorad n-type diodes, respectively. The temperature coefficient for unirradiated n-type diodes was different under low dose rate [(0.16 to 0.45)%/degrees C, continuous, cobalt] and high instantaneous dose rate [(0.07 +/- 0.02)%/degrees C, pulsed radiation]. Moreover, the temperature coefficient varies among individual diodes. Similarly, the temperature coefficient for a special unirradiated QED p-type diode was different under low dose rate (0.34%/degrees C, cobalt) and high instantaneous dose rate [(0.26 +/- 0.01)%/degrees C, pulsed radiation]. Sufficient preirradiation can eliminate dose rate dependence of the temperature coefficient. On the contrary, preirradiation cannot eliminate dose rate dependence of the diode sensitivity itself.
To evaluate the use of high-dose-rate (HDR) brachytherapy ± intensity modulated radiation therapy... more To evaluate the use of high-dose-rate (HDR) brachytherapy ± intensity modulated radiation therapy (IMRT) as salvage therapy for patients with an isolated, gross local recurrence of prostate cancer after radical prostatectomy. Between October 2009 and May 2013, the authors treated six patients with salvage iridium-192 HDR brachytherapy ± IMRT for biopsy-proven, recurrent prostate cancer post-prostatectomy. In each patient, a pelvic MRI scan or CT scan demonstrated a nodule (range 1.6, 4.7 cm) in the prostate bed. Although prostate-specific antigen values were 0.2-9.5 ng/mL at the time of salvage brachytherapy, there was no pelvic adenopathy on CT or MRI scan, and a bone scan was negative in all cases. Five patients were treated with IMRT to 4500-5040 cGy in 25-28 fractions to the prostate bed followed by two 950 cGy HDR brachytherapy fractions separated by 1-2 weeks. A sixth patient underwent HDR brachytherapy monotherapy consisting of 3800 cGy in four fractions over 3 days. Toxicities were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. Median followup was 9 months (range 3, 40 months). All six patients have been free of androgen deprivation therapy and have an undetectable prostate-specific antigen. One patient developed late Grade 2 urinary incontinence. There was no late grade ≥2 gastrointestinal toxicity. HDR brachytherapy ± IMRT is a safe and effective salvage therapy option for an isolated, gross local recurrence of prostate cancer after radical prostatectomy and merits further study.
Purpose: To report acute (!3 months) and late (O6 months) genitourinary (GU), and gastrointestina... more Purpose: To report acute (!3 months) and late (O6 months) genitourinary (GU), and gastrointestinal (GI) toxicities, and erectile dysfunction (ED) in patients treated with inverse-planned selective HDR brachytherapy boost to the dominant intraprostatic lesion (DIL) defined with magnetic resonance spectroscopy (MRS). Materials and Methods: We analyzed data prospectively collected from 20 patients treated in 2010-2011 for localized intermediate-risk prostate adenocarcinoma. All patients had an MRI/MRS to define the DIL before treatment. Afterward, they received external beam pelvic radiation (40-44 Gy in 20-22 fractions) followed by HDR ( 192 Ir) brachytherapy boost. The boost dose was 15 Gy in one fraction to the whole gland with simultaneous 3 Gy selective boost to the DIL (total of 18 Gy to DIL). All patients were planned with inverse-planning simulated annealing (IPSA). Thereafter, IPSS, International Index of Erectile Dysfunction-5 (IIEF5) and GI toxicities questionnaires were completed prospectively every three months at a followup visits. Results: The median age was 65.5 years. The median followup was 23.6 months. Fifty-five percent of the patients had clinical stage T1c, 25 % T2a, 15% T2b and 5% T2c. All patients were Gleason score (GS) 7. The pretreatment PSA was 0-5 ng/mL in 30%, 5-10 ng/mL in 60% and 10-15 ng/mL in 10% of the patients, respectively. No patients received antiandrogen therapy. The average IPSS at baseline and 1, 4 and 12 months was 6.57/35, 10.94/35, 7.32/35 and 8.47/35, respectively. At 3 months we observed a decrease of IIEF5 score from baseline of -4.45 (þ/-0.22) and -3.31 (þ/-0.39) at O6 months. At 3 months 50% of patients presented no GI symptoms and 50% occasional GI symptoms. No patients presented severe GI toxicity O6 months. Conclusions: Selective DIL image-guided (MRS) HDR brachytherapy boost in intermediate-risk cancer, is feasible with acceptable acute and late GU and GI toxicity at the price of decreasing IIEF5 score. Longer followup is necessary to evaluate tumor control.
Preoperative high-dose-rate (HDR) endorectal brachytherapy is well tolerated among patients with ... more Preoperative high-dose-rate (HDR) endorectal brachytherapy is well tolerated among patients with locally advanced rectal cancer. However, these studies excluded patients who previously received pelvic radiation therapy (RT). Because a favorable toxicity profile has been published for HDR endorectal brachytherapy, we evaluated this technique in patients who have previously received pelvic irradiation. We included patients who had received pelvic irradiation for a previous pelvic malignancy and later received preoperative HDR endorectal brachytherapy for rectal cancer. Brachytherapy was delivered to a total dose of 26 Gy in 4 consecutive daily 6.5 Gy fractions. We evaluated 10 patients who previously received pelvic external beam radiation therapy (EBRT) alone (n=6), EBRT and brachytherapy (n=2), or brachytherapy alone (n=2). The median interval between the initial course of RT and endorectal brachytherapy was approximately 11 years (range, 1-19 years). Two patients experienced a complete pathologic response while 1 patient had a near complete pathologic response. No acute grade ≥3 toxicity was observed. No intraoperative or postoperative surgical complications were observed. Preoperative HDR endorectal brachytherapy is an alternative to EBRT for patients with locally advanced rectal cancer who have previously received pelvic RT.
The myotoxic growth factor: a novel role of IGF-I in skeletal myoblasts? ... Institute for Biophy... more The myotoxic growth factor: a novel role of IGF-I in skeletal myoblasts? ... Institute for Biophysical and Clinical Research into Human Movement, Stoke-On-Trent, Cheshire, UK. ... Introduction: Prolonged elevations of proinflammatory cytokines are associated with ...
Prior studies illustrated a reduction in wound complications with the use of staged reconstructio... more Prior studies illustrated a reduction in wound complications with the use of staged reconstruction (SR) and negative pressure wound therapy when treating soft tissue sarcoma (STS) with surgical resection followed by high-dose-rate adjuvant brachytherapy. The purpose of this study is to compare the outcomes of SR and immediate reconstruction (IR) brachytherapy in recurrent STS. A retrospective review of 40 patients with recurrent STS of the local extremity and trunk treated with resection followed by adjuvant brachytherapy alone. Margin status was defined as positive (SM(+)) if there was microscopic involvement (R1) or ≤1 mm margin and negative (SM(-)) if >1 mm margin was obtained. SR and IR were compared regarding toxicity, local control, and limb preservation. Median followup was 27 months. When comparing the SR (n = 22) and IR (n = 18) cohorts, there was a significantly lower final SM(+) rate in SR (32% vs. 83%, p < 0.01). A 2-year local control benefit seen with SR (80% vs....
Journal of Biomolecular Techniques Jbt, Jul 1, 2009
Quantitative RT-PCR can be carried out as a one-or a two-step reaction. However, the choice of me... more Quantitative RT-PCR can be carried out as a one-or a two-step reaction. However, the choice of method raises controversy from the perspective of the researcher and manufacturer, because of advantages and disadvantages with both systems. We therefore hypothesize that running the RNA-to-C T ™ 2-Step kit [(Applied Biosystems (AB), Foster City, CA] using a one-step protocol (as recommended) is not appropriate for quantitation of gene expression levels and should not be performed. Consequently, we ran comparative studies of the two suggested methods to evaluate their efficiency, sensitivity, and accuracy. To ensure precession, two different PCR machines were used: the StepOnePlus system and Chromo4. In addition, the RNA-to-C T ™ 1-Step kit (recently launched by AB) was also used to compare its efficiency with these methods. Efficiency, sensitivity, and linearity were determined by standard curves generated using RNA isolated from C2 myoblasts to amplify the housekeeping gene GAPDH. When the RNA-to-C T ™ 2-Step kit was run as a two-step reaction on the Chromo4 or StepOnePlus, respectively, not only did the efficiency increase (100Ϯ1.5% and 99.7Ϯ0.95%) but also the sensitivity (comparative threshold cycle for the lowest standard: 33.2Ϯ0.5 and 32.5Ϯ0.7) and linearity (0.997Ϯ0.001 and 0.993Ϯ0.006) compared with RNA-to-C T ™ 2-Step run as one-step and RNA-to-C T ™ 1-Step kit. This is the first study to demonstrate that the RNA-to-C T ™ 2-Step kit is not reliable to be performed as a one-step reaction but as a two-step reaction, is even more sensitive than the newly launched RNA-to-C T ™ 1-Step kit.
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Papers by Amarjit Saini