Dose estimates of occupational radiation exposure during radioguided surgery of Tc-99m-PSMA-labeled lymph nodes in recurrent prostate cancer

2021 ◽  
Author(s):  
Daniel Schmidt ◽  
Jirka Grosse ◽  
Roman Mayr ◽  
Maximilian Burger ◽  
Dirk Hellwig
Keyword(s):  
Prostate Cancer ◽  
Lymph Nodes ◽  
Dose Rate ◽  
Radiation Protection ◽  
Half Life ◽  
Operation Time ◽  
Radioguided Surgery ◽  
Dose Rates ◽  
99Mtc Activity ◽  
External Exposures

Abstract Aim [99mTc]Tc-PSMA-based radioguided surgery (TPRS) represents a curative approach for localized relapse of prostate cancer. For its simplified regulatory permission, the radiation protection authorities require a 99mTc- activity below the exemption limit of 10 MBq at the time of surgery. Our aim was to determine the optimal amount of radioactivity (OAR) to comply with that limit and to estimate the maximum number of TPRS procedures per year and surgeon without triggering the full monitoring obligations. Methods In this retrospective study, a dose rate meter was calibrated using measurements on phantoms and from recently injected (1 min p. i.) patients to determine the activity in the patient from measured dose rates. The effective half-life of 99mTc-PSMA-I&S in patients was determined from repeated dose rate measurements to estimate dose parameters of relevance for radiation protection. External exposures of the surgeons were measured with personal dosimeters calibrated in Hp(10). The surgeon’s finger dose Hp(0.07) is estimated from radioactivity measured in resected lymph nodes. Potenzial incorporations were estimated for an activity of 10 MBq. Results From the first 6 subsequent patients, an effective half-life of 4.15 h was observed. Assuming an operation time 24 h p. i., the OAR was 550 MBq. Operations lasting in average 2 h in a distance of 0.25 m to the patient imply a body dose for surgeons of 4.16 µSv per procedure. Based on these estimates, the surgeon’s Hp(10) is less than 1 mSv per year with up to 241 operations per year. Hp(0.07) and potential incorporation of activity do not lead to further limitations. Summary All radiation protection regulations are met with adherence to OAR recommended here without triggering the full monitoring obligations from radiation protection regulations.

scholarly journals Dose Estimates of Occupational Radiation Exposure During Radioguided Surgery of [99mTc]Tc-PSMA-labeled Lymph Nodes in Recurrent Prostate Cancer

2020 ◽  
Author(s):  
Daniel Schmidt ◽  
Jirka Grosse ◽  
Jutta Moosbauer ◽  
Roman Mayr ◽  
Maximilian Burger ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Dose Rate ◽  
Radiation Protection ◽  
Half Life ◽  
Operation Time ◽  
Radioguided Surgery ◽  
Dose Rates ◽  
Measured Dose ◽  
External Exposures ◽  
Occupational Radiation

Abstract Background and objective[99mTc]Tc-PSMA-based radioguided surgery (TPRS) represents a curative approach for localized relapse of prostate cancer. For its simplified regulatory permission, the radiation protection authorities require a 99mTc activity below the exemption limit of 10 MBq at the time of surgery. Our aim was to determine the optimal amount of radioactivity (OAR) to comply with that limit and to estimate the maximum number of TPRS procedures per year and surgeon without triggering the full monitoring obligations.MethodsIn this retrospective study, a dose rate meter was calibrated using measurements on phantoms and from recently injected (1 min p.i.) patients to determine the activity in the patient from measured dose rates. The effective half-life of [99mTc]Tc-PSMA-I&S in patients was determined from repeated dose rate measurements up to 27 h p.i. to estimate dose parameters of relevance for radiation protection. External exposures of the surgeons were measured with personal dosimeters calibrated in Hp(10). ResultsFrom the first 6 subsequent patients, an effective half-life of 4.15 h was observed. Assuming an operation time 24 h p.i., the OAR was 550 MBq. Operations lasting in average 2 h in a distance of 0.25 m to the patient imply a body dose for surgeons of 4,16 µSv per procedure. Based on these estimates, the surgeon’s Hp(10) is less than 1 mSv per year with up to 241 operations per year. The effective dose for surgeons during the procedure determined with an electronic dosimeter is 4±1 µSv. SummaryAll radiation protection regulations are met with adherence to OAR recommended here without triggering the full monitoring obligations from radiation protection regulations.

Electron and Beta Dose Rates of UO2 Pellet and Fuel Rod

2013 ◽  
Author(s):  
Guoqing Zhang ◽  
Xuexin Wang ◽  
Jiangang Zhang ◽  
Dajie Zhuang ◽  
Chaoduan Li ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Dose Rate ◽  
Radiation Protection ◽  
High Dose Rate ◽  
High Dose ◽  
Electron Dose ◽  
Dose Rates ◽  
Fuel Rod ◽  
Calculation Results ◽  
Beta Dose

The isotopes of uranium and their daughter nuclides inside the UO2 pellet emit mono-energetic electrons and beta rays, which generate rather high dose rate near the UO2 pellet and could cause exposure to workers. In this work calculations of electron dose rates have been carried out with Monte Carlo codes, MCNPX and Geant4, for a UO2 pellet and a fuel rod. Comparisons between calculations and measurements have been carried out to verify the calculation results. The results could be used to estimate the dose produced by electrons and beta rays, which could be used to make optimization for radiation protection purpose.

Ion lifetimes in irradiated gaseous HCl

1967 ◽  
Vol 45 (24) ◽  
pp. 3079-3082 ◽  
Author(s):  
D. A. Armstrong ◽  
R. A. Back
Keyword(s):  
Dose Rate ◽  
Gas Phase ◽  
Gamma Rays ◽  
Half Life ◽  
Field Method ◽  
Dose Rates ◽  
Phase Combination

An intermittent-field method has been used to measure ion lifetimes in gaseous HCl during irradiation by gamma rays under conditions of pressure, dose rate, and vessel geometry similar to those employed in radiolysis studies. At 23 °C, with HCl pressures from 119 to 660 Torr and dose rates from 5.5 to 86 × 1010 eV cc−1 s−1, the ion half-life ranged from 6 to 30 ms. The dependence on dose rate and pressure strongly indicated that ion neutralization occurred almost entirely in the gas phase. Values of α, the gas-phase combination coefficient, were calculated; at pressures above 246 Torr the value was constant and equal to 3.1 ± 0.3 × 10−6 cc ions−1 s−1. The addition of SF6 had little effect on α, while reducing the temperature to −79 °C increased α to 5.1 × 10−6.

scholarly journals Robotic surgery using a DROP-IN beta probe – feasibility study with 68Ga-PSMA in prostate cancer specimens

2020 ◽  
Author(s):  
Francesco Collamati ◽  
Matthias van Oosterom ◽  
Micol De Simoni ◽  
Riccardo Faccini ◽  
Marta Fischetti ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Lymph Nodes ◽  
Ex Vivo ◽  
Gamma Probe ◽  
Beta Particle ◽  
Radioguided Surgery ◽  
Robot Assisted ◽  
Tumor Identification ◽  
Psma Pet ◽  
Positive Lymph Nodes

Abstract Background: Recently, a flexible DROP-IN gamma-probe was introduced for robot-assisted radioguided surgery, using traditional low-energy SPECT-isotopes. This study explores the use of a novel DROP-IN beta-particle (DROP-IN b ) detection probe to support the implementation of the large number of PET-tracers available during robot-assisted tumor-receptor-targeted resections. Methods: Following engineering of the DROP-IN b probe, robotic implementation was investigated using surgical specimens. Seven prostate cancer patients with PSMA-PET positive tumors received an intraoperative injection of ~100 MBq 68 Ga-PSMA-11, followed by prostatectomy and extended pelvic lymph node dissection. Results: The probe was able to identify the position of the tumor in the prostate specimens: S/B was > 5 when pathology confirmed that the tumor was located <1 mm below the specimen surface. PSMA-PET positive lymph nodes, as found in two patients, could be identified with the DROP-IN b probe (S/B>3). Conclusions: This ex vivo study underlines the potential to use a DROP-IN b probe for intraoperative tumor identification on the prostate surface and confirmation of PSMA-PET positive lymph nodes.

scholarly journals A DROP-IN Beta Probe for Robot-Assisted 68Ga-PSMA Radioguided Surgery: First Ex Vivo Technology Evaluation Using Prostate Cancer Specimens

2020 ◽  
Author(s):  
Francesco Collamati ◽  
Matthias van OOsterom ◽  
Micol De Simoni ◽  
Riccardo Faccini ◽  
Marta Fischetti ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Lymph Nodes ◽  
Ex Vivo ◽  
Gamma Probe ◽  
Beta Particle ◽  
Radioguided Surgery ◽  
Robot Assisted ◽  
Psma Pet ◽  
Positive Lymph Nodes

Abstract Background: Recently, a flexible DROP-IN gamma-probe was introduced for robot-assisted radioguided surgery, using traditional low-energy SPECT-isotopes. In parallel, a novel approach to achieve sensitive radioguidance using beta-emitting PET-isotopes has been proposed. Integration of these two concepts would allow to exploit the use of PET-tracers during robot-assisted tumor-receptor-targeted. In this study, we’ve engineered and validated the performance of a novel DROP-IN beta-particle (DROP-INb) detector.Methods: Seven prostate cancer patients with PSMA-PET positive tumors received an additional intraoperative injection of ~70 MBq 68Ga-PSMA-11, followed by robot-assisted prostatectomy and extended pelvic lymph node dissection. The surgical specimens from these procedures were used to validate the performance of our DROP-INb probe prototype, with merged a scintillating detector with a housing optimized for a 12 mm trocar and prograsp instruments. Results: After optimization of the detector and probe housing via Monte Carlo simulations, the resulting DROP-INb probe prototype was tested in a robotic setting. In the ex vivo setting, the probe – positioned by the robot- was able to identify 68Ga-PSMA-11 containing hot-spots in the surgical specimens: signal-to-background (S/B) was > 5 when pathology confirmed that the tumor was located <1 mm below the specimen surface. 68Ga-PSMA-11 containing (and PET positive) lymph nodes, as found in two patients, were also confirmed with the DROP-INb probe (S/B>3). The rotational freedom of the DROP-IN design and the ability to manipulate the probe with the prograsp tool allowed the surgeon to perform autonomous beta tracing. Conclusions: This study demonstrates the feasibility of beta-radioguided surgery in a robotic context by means of a DROP-INb detector. When translated to an in vivo setting in the future, this technique could provide a valuable tool in detecting tumor remnants on the prostate surface and in confirmation of PSMA-PET positive lymph nodes.

scholarly journals Multiparametric MRI and 18F-DCFPyL PET/CT for detection of locally recurrent prostate cancer after low dose rate brachytherapy

2020 ◽  
Author(s):  
Stephanie M. Walker ◽  
Martina Fernandez ◽  
Soumyajit Roy ◽  
Esther Mena ◽  
Jonathan Sackett ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Lymph Node ◽  
Local Recurrence ◽  
Lymph Nodes ◽  
Dose Rate ◽  
Low Dose ◽  
Imaging Modality ◽  
Low Dose Rate ◽  
Ldr Brachytherapy ◽  
Pet Ct

Abstract Background and purpose: Both multiparametric magnetic resonance imaging (mpMRI) and prostate specific membrane antigen (PSMA)-targeting positron emission tomography (PET) imaging have shown promise in early localization of prostate cancer (PCa) recurrence after primary external beam radiotherapy. Detecting recurrence after brachytherapy for PCa using MRI is significantly hampered by susceptibility artifacts secondary to brachy seeds. Here, we compare the efficacy of 18F-DCFPyL (2-(3-{1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid) PET/CT versus mpMRI for detecting sites of local recurrence after low dose rate (LDR) brachytherapy for prostate cancer.Materials and methods: A total of 155 patients with a history of recurrent PCa who underwent mpMRI at 3 Tesla and 18F-DCFPyL PET/CT were retrospectively reviewed. Patients who underwent LDR brachytherapy for PCa and had subsequent biochemical recurrence (BCR) followed by mpMRI and 18F-DCFPyL PET/CT were included in this study. mpMRI was performed on a 3T scanner with endorectal and surface coils and images were prospectively read by a single expert radiologist. The 18F-DCFPyL PET/CT scan was prospectively interpreted by two nuclear medicine physicians. Patients underwent targeted biopsy when deemed clinically necessary and specimens were interpreted by an expert GU pathologist. Positivity rates (PR) from mpMRI and 18F-DCFPyL PET/CT were compared, and pathology results were used to calculate the positive predictive value (PPV) of each imaging modality for detecting PCa recurrence.Results: 15 patients who underwent LDR brachytherapy and had subsequent biochemical failure were imaged with mpMRI and 18F-DCFPyL PET/CT. 18 non-lymph node lesions were identified on at least one imaging modality. The PR for detection of intraprostatic lesions was 60% (9/15) for both PET/CT and mpMRI, with 3 prostate lesions detected by only one modality. 18F-DCFPyL PET/CT identified pelvic and extra-pelvic lymph nodes in 8 (53%) patients, while mpMRI noted positive lymph node findings in only 2 (13%) patients. A total of 15 lesions corresponding to 9 patients were targeted for biopsy. The PPV of 18F-DCFPyL PET/CT and mpMRI for the detection of local recurrence were 84.6% and 71.4%, respectively. For the detection of intraprostatic lesions, 18F-DCFPyL PET/CT and mpMRI had a PPV of 87.5% and 71.4%, respectively. Conclusion: This case series analysis suggests that 18F-DCFPyL PET/CT may detect local and regional recurrent PCa after LDR brachytherapy at a higher rate than mpMRI and that it has the potential to detect suspicious pelvic lymph nodes at a much higher rate. Further studies are needed to validate these findings in larger cohorts.

EVALUATION OF RADIATION DOSE IN DIFFERENT POSITIONS AROUND THE PATIENT TABLE DURING INTERVENTIONAL CARDIOLOGY PROJECTIONS

2019 ◽  
Vol 188 (2) ◽  
pp. 199-204
Author(s):  
Y Lahfi ◽  
A Ismail
Keyword(s):  
Radiation Dose ◽  
Radiation Exposure ◽  
Dose Rate ◽  
Radiation Protection ◽  
Interventional Cardiology ◽  
X Ray ◽  
Dose Rates ◽  
Patient Table ◽  
The Right

Abstract The aim of the present study was to evaluate the radiation exposure around the patient table as relative to the cardiologist position dose value. The dose rates at eight points presuming staff positions were measured for PA, LAO 30° and RAO 30° radiographic projections, and then normalized to the cardiologist’s position dose-rate value. The results show that in PA and RAO 30° projections, the normalized dose rate was higher by 9–22% at the right side of the table at a distance of 50 cm, while it was higher up to 31% at the left side for the same measured points in the LAO 30°. The differences of normalized dose rates for the both table sides were lower and decreased at farther positions. The obtained results correspond to the recommendations of staff radiation protection in Cath-labs with regards to X-ray tube and detector positions.

scholarly journals Multiparametric MRI and 18F-DCFPyL PET/CT for detection of locally recurrent prostate cancer after low dose rate brachytherapy

2020 ◽  
Author(s):  
Stephanie M. Walker ◽  
Martina Fernandez ◽  
Soumyajit Roy ◽  
Esther Mena ◽  
Jonathan Sackett ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Lymph Node ◽  
Local Recurrence ◽  
Lymph Nodes ◽  
Dose Rate ◽  
Low Dose ◽  
Imaging Modality ◽  
Low Dose Rate ◽  
Ldr Brachytherapy ◽  
Pet Ct

Abstract Background and purpose: Both multiparametric magnetic resonance imaging (mpMRI) and prostate specific membrane antigen (PSMA)-targeting positron emission tomography (PET) imaging have shown promise in early localization of prostate cancer (PCa) recurrence after primary external beam radiotherapy. Detecting recurrence after brachytherapy for PCa using MRI is significantly hampered by susceptibility artifacts secondary to brachy seeds. Here, we compare the efficacy of 18F-DCFPyL (2-(3-{1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid) PET/CT versus mpMRI for detecting sites of local recurrence after low dose rate (LDR) brachytherapy for prostate cancer.Materials and methods: A total of 155 patients with a history of recurrent PCa who underwent mpMRI at 3 Tesla and 18F-DCFPyL PET/CT were retrospectively reviewed. Patients who underwent LDR brachytherapy for PCa and had subsequent biochemical recurrence (BCR) followed by mpMRI and 18F-DCFPyL PET/CT were included in this study. mpMRI was performed on a 3T scanner with endorectal and surface coils and images were prospectively read by a single expert radiologist. The 18F-DCFPyL PET/CT scan was prospectively interpreted by one of two nuclear medicine physicians. Patients underwent targeted biopsy when deemed clinically necessary and specimens were interpreted by an expert GU pathologist. Positivity rates (PR) from mpMRI and 18F-DCFPyL PET/CT were compared, and pathology results were used to calculate the positive predictive value (PPV) of each imaging modality for detecting PCa recurrence.Results: 15 patients who underwent LDR brachytherapy and had subsequent biochemical failure were imaged with mpMRI and 18F-DCFPyL PET/CT. 18 non-lymph node lesions were identified on at least one imaging modality. The PR for detection of intraprostatic lesions was 60% (9/15) for both PET/CT and mpMRI, with 3 prostate lesions detected by only one modality. 18F-DCFPyL PET/CT identified pelvic and extra-pelvic lymph nodes in 8 (53%) patients, while mpMRI noted positive lymph node findings in only 2 (13%) patients. A total of 15 lesions corresponding to 9 patients were targeted for biopsy. The PPV of 18F-DCFPyL PET/CT and mpMRI for the detection of local recurrence were 84.6% and 71.4%, respectively. For the detection of intraprostatic lesions, 18F-DCFPyL PET/CT and mpMRI had a PPV of 87.5% and 71.4%, respectively. Conclusion: This case series analysis suggests that 18F-DCFPyL PET/CT may detect local and regional recurrent PCa after LDR brachytherapy at a higher rate than mpMRI and that it has the potential to detect suspicious pelvic lymph nodes at a much higher rate. Further studies are needed to validate these findings in larger cohorts.

Коэффициент эффективности (DDREF) дозы и мощноcти доз: ненужные, спорные и противоречивые вопросы

2017 ◽  
Vol 62 (2) ◽  
pp. 13-27
Author(s):  
Julio Abel ◽  
Julio Abel
Keyword(s):  
Radiation Exposure ◽  
Dose Rate ◽  
Radiation Protection ◽  
Radiation Effects ◽  
Radiation Risk ◽  
Mathematical Formulation ◽  
Indirect Evidence ◽  
Dose Rates ◽  
Radiation Risks ◽  
Risk Estimates

Purpose: The aim of the paper is to review the genesis and evolution of the concept termed dose and dose rate effectiveness factor or DDREF, to expose critiques on the concept and to suggest some curse of action on its use. Material and methods: Mainly using the UNSCEAR reporting and ICRP recommendations as the main reference material, the paper describes the evolution (since the 70’s) of the conundrum of inferring radiation risk at low dose and dose-rate. People are usually exposed to radiation at much lower doses and dose rates than those for which quantitative evaluations of incidence of radiation effects are available – a situation that tempted experts to search for a factor relating the epidemiological attribution of effects at high doses and dose-rates with the subjective inference of risk at low doses and dose-rates. The formal introduction and mathematical formulation of the concept by UNSCEAR and ICRP (in the 90’s), is recalled. It is then underlined that the latest UNSCEAR radiation risk estimates did not use a DDREF concept, making it de facto unneeded for purposes of radiation risk attribution. The paper also summarizes the continuous use of the concept for radiation protection purposes and related concerns as well as some current public misunderstandings and apprehension on the DDREF (particularly the aftermath of the Fukushima Dai’ichi NPP accident). It finally discusses epistemological weaknesses of the concept itself. Results: It seems that the DDREF has become superseded by scientific developments and its use has turned out to be unneeded for the purposes of radiation risk estimates. The concept also appears to be arguable for radiation protection purposes, visibly controversial and epistemologically questionable Conclusions: It is suggested that: (i) the use of the DDREF can be definitely abandoned for radiation risk estimates; (ii) while recognizing that radiation protection has different purposes than radiation risk estimation, the discontinuation of using a DDREF for radiation protection might also be considered; (iii) for radiation exposure situations for which there are available epidemiological information that can be scientifically tested (namely which is confirmable and verifiable and therefore falsifiable), radiation risks should continue to be attributed in terms of frequentistic probabilities; and, (iv) for radiation exposure situations for which direct scientific evidence of effects is unavailable or unfeasible to obtain, radiation risks may need to be inferred on the basis of indirect evidence, scientific reasoning and professional judgment aimed at estimating their plausibility in terms of subjective probabilities.

Radiation exposure around patients after administration of 123I-MIBG

2002 ◽  
Vol 41 (05) ◽  
pp. 221-223
Author(s):  
S. Ofluoglu ◽  
J. Preitfellner ◽  
B. J. Fueger ◽  
T. Traub ◽  
C. Novotny ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Dose Rate ◽  
Half Life ◽  
Maximum Dose ◽  
Radiation Detectors ◽  
Mibg Scintigraphy ◽  
Dose Limit ◽  
Annual Dose ◽  
Dose Rates ◽  
M 12

SummaryAim: Estimation of the radiation exposure to neighbouring patients, personnel and relatives deriving from patients undergoing 123I-MIBG scintigraphy. Methods: For scintigraphic studies, 16 patients with suspected pheocromocytoma were injected with 340 ± 30 MBq 123I-MIBG. Dose rates were measured at a distance of 0.5 m, 1 m, and 2 m after 10 min, 3 h, 21 h, 45 h, and 68 h using three calibrated portable radiation detectors. The measured values were background corrected. Results: Ten minutes after injection the dose rate was 10.5 µS/h at a distance of 0.5 m, 3.78 µS/h at 1 m, and 0.95 µS/h at 2 m. The effective half-life was estimated to 8.68 ± 0.15 h. The maximum dose in a distance of 1 m for neighbouring patients was 46 µS/h, for personnel in a ward 27 µS/h, and to relatives in a distance of 2 m 12 µS/h. Conclusion: This study demonstrates that the calculated exposure to people around patients after 123I-MIBG injection is well below the maximum permissible annual dose limit of 1 mSv for not professionally exposed persons.

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