Dosimetry System Research Articles

Clinical pilot study for EPID-based in vivo dosimetry using EPIgray™ for head and neck VMAT.

This work details the clinical pilot study methodology used at Wellington Blood and Cancer Centre (WBCC) before the clinical release of in vivo dosimetry (IVD) system EPIgray™ for head and neck (H&N) volumetric modulated arc therapy (VMAT) treatments. Clinical pilot studies make it possible to select appropriate, department-specific tolerance ranges for the treatment type and site under investigation. An IVD clinical pilot study of H&N VMAT treatments was conducted over 3months at WBCC using EPIgray™ dose reconstruction software and included 12 patients and 32 individual treatment fractions. Statistical analysis of the dose deviations between the treatment planning system (TPS) dose and EPIgray™ reconstructed dose confirmed that a deviation tolerance range of ± 7.0% was an appropriate choice for H&N VMAT at WBCC.

AAPM WGTG51 Report 374: Guidance for TG-51 reference dosimetry.

Practical guidelines that are not explicit in the TG-51 protocol and its Addendum for photon beam dosimetry are presented for the implementation of the TG-51 protocol for reference dosimetry of external high-energy photon and electron beams. These guidelines pertain to:(i)measurement of depth-ionization curves required to obtain beam quality specifiers for the selection of beam quality conversion factors, (ii)considerations for the dosimetry system and specifications of a reference-class ionization chamber, (iii)commissioning a dosimetry system and frequency of measurements, (iv)positioning/aligning the water tank and ionization chamber for depth ionization and reference dose measurements, (v)requirements for ancillary equipment needed to measure charge (triaxial cables and electrometers) and to correct for environmental conditions, and (vi)translation from dose at the reference depth to that at the depth required by the treatment planning system. Procedures are identified to achieve the most accurate results (errors up to 8% have been observed) and, where applicable, a commonly used simplified procedure is described and the impact on reference dosimetry measurements is discussed so that the medical physicist can be informed on where to allocateresources.

Risk of cataract of different morphological types in Urals population chronically exposed at low doses

ObjectiveTo assess the risk of lens opacity depending on the dose in the population exposed to external and internal radiation for a long time, based on a long-term clinical follow-up of the cohorts of people exposed to radiation as a result of two radiation accidents in the South Urals. MethodsA layer-by-layer morphological study of the lens of 1,377 exposed individuals was conducted according to a special program in the Clinical Department of the Urals Research Center for Radiation Medicine (URCRM) 68 years after the onset of exposure. Lens changes were classified in accordance with the lens opacities classification (LOCS) III and included images of lens. To calculate the doses to lens, the data were taken into account, including the person's residence history in the radioactively contaminated territory, age and sex that affected their lifestyle and diet, radionuclide distribution in organs and tissues. Individualized lens doses were calculated using Techa River Dosimetry System (TRDS)-2016. Case-control method was used for statistical analysis. ResultsIndividual values of absorbed dose to lens ranged from 0 to 600 ​mGy. A dose-dependent increased risk of posterior subcapsular cataract (PSC) (OR ​1.54, 95%CI: 1.04–2.27) and nuclear cataract (OR ​1.84, 95%CI: 1.14–2.95) was found among chronically exposed individuals by a case-control method. No evidence of dose effect was found for cortical cataracts. ConclusionsThe results showed that population exposed to long-term chronic low-dose radiation was subjected to an increased risk of PSC and nuclear cataract development.

A new proposed validation method for low energy electron beam processing of dry spices

Food processing with ionizing technologies must comply with validation requirements laid out by national regulatory bodies and international standards. This paper describes a new proposed method to meet the requirements for microbial decontamination treatment of spices and herbs with low-energy electron beam (LEEB) processing. The demonstration of robust process and product qualification protocols is necessary for regulatory approval and adoption of LEEB process in the food industry. The bulk flow of loose seeds was measured and optimized for treatment, a dosimetry system implemented, and methods for assessing Salmonella spp. reduction were developed combining high- and low-energy electron beam microbial inactivation data. Data is presented indicating 5-log reduction of Salmonella enterica serovar Rissen on black peppercorns, demonstrating the effectiveness of the LEEB treatment. The validation method described in this paper is applicable to most loose, dry, whole spices and herbs.

Development of a real-time in vivo dosimetry tool for electron beam therapy using a flexible thin film solar cell coated with scintillator powder.

A real-time solar cell based in vivo dosimetry system (SC-IVD) was developed using a flexible thin film solar cell and scintillating powder. The present study evaluated the clinical feasibility of the SC-IVD in electron beam therapy. A thin film solar cell was coated with 100 mg of scintillating powder using an optical adhesive to enhance the sensitivity of the SC-IVD. Calibration factors were obtained by dividing the dose, measured at a reference depth for 6-20 MeV electron beam energy, by the signal obtained using the SC-IVD. Dosimetric characteristics of SC-IVDs containing variable quantities of scintillating powder (0-500 mg) were evaluated, including energy, dose rate, and beam angle dependencies, as well as dose linearity. To determine the extent to which the SC-IVD affected the dose to the medium, doses at R90 were compared depending on whether the SC-IVD was on the surface. Finally, the accuracy of surface doses measured using the SC-IVD was evaluated by comparison with surface doses measured using a Markus chamber. Charge measured using the SC-IVD increased linearly with dose and was within 1% of the average signal according to the dose rate. The signal generated by the SC-IVD increased as the beam angle increased. The presence of the SC-IVD on the surface of a phantom resulted in a 0.5%-2.2% reduction in dose at R90 for 6-20 MeV electron beams compared with the bare phantom. Surface doses measured using the SC-IVD system and Markus chamber differed by less than 5%. The dosimetric characteristics of the SC-IVD were evaluated in this study. The results showed that it accurately measured the surface dose without a significant difference of dose in the medium when compared with the Markus chamber. The flexibility of the SC-IVD allows it to be attached to a patient's skin, enabling real-time and cost-effective measurement.

Hip Imaging in Children With Cerebral Palsy: Estimation and Intrapatient Comparison of Patient-Specific Radiation Doses of Low-Dose CT and Radiography.

Hip displacement is the second most common orthopedic problem affecting children with cerebral palsy (CP). Routine radiographic hip surveillance typically involves an anteroposterior (AP) pelvis radiograph. Unfortunately, this imaging protocol is limited by its projectional technique and the positioning challenges in children with CP. Alternatively, hip low-dose computed tomography (LDCT) has been advocated as a more accurate strategy for imaging surveillance as it provides biofidelic details of the hip that is independent of patient positioning. However, the tradeoff is the (presumed) higher radiation dose to the patient. The goal of this study is to estimate patient-specific radiation doses of hip LDCTs and AP pelvis radiographs in CP patients, and perform an intrapatient dose comparison. A search of our imaging database was performed to identify children with CP who underwent hip LDCT and AP pelvis radiograph within 6 months of each other. The LDCTs were performed using weight-adjusted kVp and tube current modulation, whereas the radiographs were obtained with age-/size-adjusted kVp/mAs. The patient-specific organ and effective doses for LDCT were estimated by matching the patients to a nonreference pediatric phantom library from the National Cancer Institute Dosimetry System for Computed Tomography database with Monte Carlo-based dosimetry. The patient-specific organ and effective doses for radiograph were estimated using the National Cancer Institute Dosimetry System for Radiography and Fluoroscopy with Monte Carlo-based dose calculation. Dose conversion k-factors of dose area product for radiography and dose length product for LDCT were adapted, and the estimation results were compared with patient-specific dosimetry. Our study cohort consisted of 70 paired imaging studies from 67 children (age, 9.1 ± 3.3 years). The patient-specific and dose length product-based effective doses for LDCT were 0.42 ± 0.21 mSv and 0.59 ± 0.28 mSv, respectively. The patient-specific and dose area product-based effective doses for radiography were 0.14 ± 0.09 mSv and 0.08 ± 0.06 mSv, respectively. The radiation dose for a hip LDCT is ~4 times higher than pelvis radiograph, but it is still very low and poses minimal risk to the patient.

Radioluminescence imaging feasibility for robotic radiosurgery field size quality assurance.

To investigate the feasibility of radioluminescence imaging (RLI) as a novel 2D quality assurance (QA) dosimetry system for CyberKnife®. We developed a field size measurement system based on a commercial complementary metal oxide semiconductor (CMOS) camera facing a radioluminescence screen located at the isocenter normal to the beam axis. The radioluminescence light collected by a lens was used to measure 2D dose distributions. An image transformation procedure, based on two reference phantoms, was developed to correct for projective distortion due to the angle (15°) between the optical and beam axis. Dose profiles were measured for field sizes ranging from 5 mm to 60 mm using fixed circular and iris collimators and compared against gafchromic (GC) film. The corresponding full width at half maximum (FWHM) was measured using RLI and benchmarked against GC film. A small shift in the source-to-surface distance (SSD) of the measurement plane was intentionally introduced to test the sensitivity of the RLI system to field size variations. To assess reproducibility, the entire RLI procedure was tested by acquiring the 60mm circle field three times on two consecutive days. The implemented procedure for perspective image distortion correction showed improvements of up to 1 mm using the star phantom against the square phantom. The FWHM measurements using the RLI system indicated a strong agreement with GC film with maximum absolute difference equal to 0.131 mm for fixed collimators and 0.056 mm for the iris. A 2D analysis of RLI with respect to GC film showed that the differences in the central region are negligible, while small discrepancies are in the penumbra region. Changes in field sizes of 0.2 mm were detectable by RLI. Repeatability measurements of the beam FWHM have shown a standard deviation equal to 0.11mm. The first application of a RLI approach for CyberKnife® field size measurement was presented and tested. Results are in agreement with GC film measurements. Spatial resolution and immediate availability of the data indicate that RLI is a feasible technique for robotic radiosurgeryQA.

RESPONSE OF PLASTIC TRACK DETECTOR OF THE TASTRAK TYPE TO NEUTRONS OF PU–BE SOURCE

The solid-state nuclear track detectors are widely used in a variety of nuclear physics experiments and radiation protection. The paper presents the first results of the newly acquired TASLImage™ neutron dosimetry system at the Slovak University of Technology in Bratislava. A comparison of experimental and calculated responses of a TASTRAK plastic nuclear track detector to neutron spectrum of Pu-Be source is presented. The ambient dose equivalents determined by the TASLImage™ system are compared with the ones measured by the NuDET-ENE neutron detector based on the use of ZnS(Ag) scintillator covered with a thin film of 6LiF thermal neutron converter accommodated inside the HDPE moderator. The first results are concluded, and further research needs are identified.

LONG-TERM PERFORMANCE OF AN OPTICALLY STIMULATED LUMINESCENT SYSTEM FOR DOSE EQUIVALENT HP(10) MEASUREMENT.

The performance of an optically stimulated luminescent (OSL) passive dosimetry system named MicroStar reader manufactured by Landauer Inc and acquired in 2011 is assessed in this study. The assessment carried out is based on the results of the intercomparison (IC) exercises organised by the International Atomic Energy Agency in 2013 and 2021. The IC results show that this OSL reader can maintain good performance after long-term usage provided adequate maintenance and calibration operations are carried out. Moreover, this assessment also reveals the importance of using a higher number of measurements per data point for the non-linearity test of the IEC 62387 standard.

Assessment of occupational dose reduction with the use of a floor mounted mobile lead radiation protection shield

With the increasing number and complexity of interventional cardiology procedures, there is the potential for higher occupational radiation doses to the interventionists. In order to reduce the radiation exposure to interventionists, a number of different radiation protection measures can be implemented; the most common of which being personal protective equipment in the form of a lead-equivalent apron. However, significant development has been achieved with mobile lead equivalent radiation protection devices, which provide enhanced radiation protection without the requirement of being directly worn by staff. The RAMPART M1128 radiation protection shield is one of these devices. The dose reduction provided to staff within a Cardiac Catheterisation Laboratory was assessed via the use of electronic personal dosimeters with the Philips live dosimetry system DoseAware (Philips DoseAware). A 60% dose reduction to the primary operator can be achieved with the Rampart device. Further dose reductions are possible for other individuals in the range of 65%–84%. Additionally, dose rate measurements were taken in a simulated clinical set-up using a phantom, which showed that the device provided a 65% dose reduction at eye level and a 90% dose reduction at chest level for the primary operator position. This significant dose reduction means that there is the potential for at least the primary operator to wear a lead apron of reduced lead equivalence specification when the Rampart device is in use, without increasing their occupational exposure and potentially reducing musculoskeletal pain due to the reduced weight.

ЗАБОЛЕВАЕМОСТЬ И СМЕРТНОСТЬ ОТ ОПУХОЛЕЙ ЦЕНТРАЛЬНОЙ НЕРВНОЙ СИСТЕМЫ В КОГОРТЕ РАБОТНИКОВ, ПОДВЕРГШИХСЯ ХРОНИЧЕСКОМУ ОБЛУЧЕНИЮ

Purpose: To analyze incidence and mortality rates of central nervous system (CNS) primary tumors (PT) in the cohort of workers chronically exposed to radiation. Material and methods: Study cohort included 22237 Mayak Production Association workers. Work history data and dose estimates from the “Mayak Worker Dosimetry System 2013” were used. Clinical and epidemiology data were obtained from the “Clinic” database. Crude and age-adjusted (by indirect method) incidence and mortality rates for CNS PT per 100000 person-years were calculated. Standardized incidence and mortality trends were analyzed by Jointpoint 4.0.4. Results: 53 cases and 47 deaths from malignant neoplasms (MN) of brain and spinal cord, cerebral nerve and other parts of CNS (C70–C72 ICD-10 codes) as well as 40 cases and 7 deaths from non-malignant neoplasms (NMN) of brain and other parts of CNS (D-33 ICD-10 code) were identified. CNS MN were more frequent among males (83 %), and CNS NMN were more frequent among females (55 %). Both CNS MN and NMN developed at younger ages among males as compared with females, CNS PT frequency increased with increased attained age. Analysis in relation to calendar period revealed the increasing trend for CNS PT incidence among females only (р=0,008). Effects of chronic occupational radiation exposure on CNS PT incidence and mortality rates were not established either among males or females. Conclusion: Findings should be considered as preliminary and require further studies.

Performance of a scintillation imaging system for relative dosimetry in pencil beam scanning proton therapy

The proton spot scanning system requires extensive periodic quality assurance procedures to guarantee the conformality of planned dose distribution to the tumor. Detectors with stable, accurate, and fast data acquisition properties make the quality assurance procedures more efficient. For this purpose, a camera-based scintillation imaging system has been developed. A high scintillation efficiency screen coupled with a high-performance camera improved the dose sensitivity and precision required for the measurements. The dose distribution within the scintillating screen can be analyzed from the captured light distribution image in a relatively straightforward way.In this study, we investigated the performance of a 2D detection system by using a scintillating screen (silver-activated zinc sulfide powder deposited on the surface of a plastic scintillator HND-S2) for dose distribution measurement. The characteristics of the system in terms of response reproducibility, linear dose–response, and beam spot size dependence on proton dose were assessed in a series of proton irradiations. To evaluate the accuracy of lateral dose profiles measured by the ZnS: Ag based scintillating screen, we compared the results with plastic scintillator BC-408 and some commercial quality control devices. Several measurements were conducted with proton energies ranging from 70–235 MeV. We found that the detector showed stable response reproducibility (better than 1.6%) and good dose–response linearity (R2¿0.999). The beam spot size was independent of proton dose when the response of the pixel value was between 10% and 90% of the maximum. The in-air spot size measured by the ZnS: Ag based scintillating screen was found to be slightly smaller than the Lynx detector while the BC-408 showed a slightly bigger spot size. The inter-comparison results for scanned fields showed good agreements. The observed differences in beam profile measurement between the inorganic and organic scintillating screens were mainly due to their optical properties and structures. The developed scintillation imaging system with an effective resolution of 0.12 mm proved to be a reliable device for efficiently performing the quality checks for two-dimensional proton dosimetry.

Transit dose measurements using alanine and diode-based dosimeters

The growing interest in low-dose (< 100 Gy) radiation processing applications has raised concerns about accurately measuring the absorbed dose in irradiated materials. Depending on the irradiator design, the transit time due to the radioactive source movement (or the product itself) until the stable irradiation position might affect the predicted absorbed dose. This work aims to evaluate the transit dose in a 60Co Gammacell 220-Nordion irradiator, which has radioactive sources settled at the bottom of a lead shielding. When the facility is on, the product and the dosimeter are mechanically guided down to the irradiation position, and hereafter the selected exposure time starts to be counted. At the end of irradiation, both product and dosimeter rise to the initial position enabling them to be gathered by the operator. The product is continuously irradiated at different dose rates during its fall and rise movement, preventing the transit dose from being obtained straightforward. The experimental approach adopted is to assess the transit time, and thus the transit dose, using an online diode-based dosimetry system previously calibrated against reference standard alanine dosimeters. The agreement between the transit doses attained with the diode (0.41 ± 0.02) Gy and alanine ((0.38 ± 0.01) Gy validates the method herein proposed.

Change in image-guided planning strategies over time impacts oncologic and survival outcomes for intracavitary cervical cancer brachytherapy

PURPOSEIntracavitary cervical brachytherapy (BT) has transitioned from a two-dimensional nonvolumetric (NV) dosimetry system to three-dimensional computed tomography (CT) and/or magnetic resonance imaging (MRI)-based planning techniques. The purpose of this study is to retrospectively evaluate the relative improvements in image-guided planning strategies over time with regards to dosimetry, survival, and toxicity. METHODS AND MATERIALSA single site retrospective review of 95 locally advanced cervical cancer patients treated with concurrent chemoradiation and high dose rate BT from 2009 to 2016 were divided into three BT planning groups: point-A based NV dosimetry using CT imaging (n = 37), CT-based volumetric dosimetry (n = 33), and MRI-based volumetric dosimetry (n = 25). Overall survival (OS), progression free survival (PFS), and pelvic control (PC) at 5 years were plotted using Kaplan–Meier curves. Univariate and multivariate (MVA) cox proportional-hazards models calculated hazard-ratios (HZ). Finally, acute and late grade 3–4 toxicities were compared between the cohorts. RESULTSBoth MRI and CT had significantly less D2cc to bowel (p < 0.001) and sigmoid (p < 0.001) compared to NV-based planning. On MVA, age (<60 vs. ≥60 years) was significant for worse 5-year OS (HZ: 2.48) and PC (HZ: 5.25). MRI, with NV as the reference, had significantly improved 5-year OS (HZ: 0.26), PFS (HZ: 0.34) and PC (HZ: 0.16). There was no significant difference in grade ≥3 toxicities between the cohorts. CONCLUSIONSCT and MRI-based 3D planning had significantly less D2cc to bowel and sigmoid. MRI-based planning had significant improvement in 5-year OS, PFS, and LC compared to NV on MVA.

A Review of PRESAGE Radiochromic Polymer and the Compositions for Application in Radiotherapy Dosimetry.

Recent advances in radiotherapy technology and techniques have allowed a highly conformal radiation to be delivered to the tumour target inside the body for cancer treatment. A three-dimensional (3D) dosimetry system is required to verify the accuracy of the complex treatment delivery. A 3D dosimeter based on the radiochromic response of a polymer towards ionising radiation has been introduced as the PRESAGE dosimeter. The polyurethane dosimeter matrix is combined with a leuco-dye and a free radical initiator, whose colour changes in proportion to the radiation dose. In the previous decade, PRESAGE gained improvement and enhancement as a 3D dosimeter. Notably, PRESAGE overcomes the limitations of its predecessors, the Fricke gel and the polymer gel dosimeters, which are challenging to fabricate and read out, sensitive to oxygen, and sensitive to diffusion. This article aims to review the characteristics of the radiochromic dosimeter and its clinical applications. The formulation of PRESAGE shows a delicate balance between the number of radical initiators, metal compounds, and catalysts to achieve stability, optimal sensitivity, and water equivalency. The applications of PRESAGE in advanced radiotherapy treatment verifications are also discussed.

Dose rate mapping of an industrial 60Co irradiator using an online photodiode-based dosimetry system

In this work, a housemade dosimetry system based on a thin photodiode is applied for online mapping of dose rates, between 2.6 and 37.7 Gy/h, delivered by a Panoramic 60Co industrial facility. The operational principle of the dosimeter relies on the real-time acquisition of the induced currents from the irradiated diode operating in the short-circuit mode without externally applied voltage. The radial mapping of the radiation field is performed by rotating the diode around the central axis of the panoramic irradiator, covering 360° at intervals of 18°. The results are benchmarked with alanine dosimeters, Monte Carlo simulations, and reference dose rates retrieved from the facility calibration. The overall consistency of the whole data complies with the maximum response variation (8%, k = 2) recommended by the International Standard Protocols for routine dosimeters in radiation processing dosimetry. It reveals that the photodiode-dosimetry system is a reliable alternative to map dose rate fields and the effectiveness of Monte Carlo simulations as a predictive tool for dose rate measurements in an irradiator.

Performance of radiophotoluminescence personal dosimeters in terms of the ICRU Report 95’s operational quantities

The objective of this work is to assess the photon energy and angle response of the radiophotoluminescence (RPL) personal dosimetry system used at the Paul Scherrer Institute (PSI) in terms of the operational quantities for external radiation exposure personal dose, Hp, and personal absorbed dose in local skin, Dlocal skin, defined in the Report 95 of the International Commission on Radiation Measurements and Units (ICRU). The RPL responses in terms of the “new” ICRU Report 95 quantities to a range of photon energies and irradiation angles were calculated using the RPL responses in terms of the personal dose equivalent Hp(10) and Hp(0.07) from the ICRU Report 51, previously obtained during commissioning of the RPL system, and the conversion coefficients from air kerma to the various operational quantities. The indicated value provided by the current dosimetry algorithm over-estimates the personal dose, Hp, in the low-energy range (¡ 33 keV), whereas the estimation for the personal absorbed dose in local skin, Dlocal skin, with the current system is satisfactory. A new dosimetry algorithm was developed making use of the five signals obtained from the RPL detectors, corresponding to the signal from regions of RPL glass under five different filters, to improve the Hp estimation by the RPL dosimeters. The results indicate that, in this case, the new algorithm may be sufficient to achieve satisfactory photon energy and angle response in terms of the ICRU Report 95 quantity Hp without a physical redesign of the dosimeter badges. A few photon mixed fields were also investigated, but a complete algorithm for photon-beta mixed field remains to be developed.

Particles Detection System with CR-39 Based on Deep Learning

We present a novel method that we call FAINE, fast artificial intelligence neutron detection system. FAINE automatically classifies tracks of fast neutrons on CR-39 detectors using a deep learning model. This method was demonstrated using a LANDAUER Neutrak® fast neutron dosimetry system, which is installed in the External Dosimetry Laboratory (EDL) at Soreq Nuclear Research Center (SNRC). In modern fast neutron dosimetry systems, after the preliminary stages of etching and imaging of the CR-39 detectors, the third stage uses various types of computer vision systems combined with a manual revision to count the CR-39 tracks and then convert them to a dose in mSv units. Our method enhances these modern systems by introducing an innovative algorithm, which uses deep learning to classify all CR-39 tracks as either real neutron tracks or any other sign such as dirt, scratches, or even cleaning remainders. This new algorithm makes the third stage of manual CR-39 tracks revision superfluous and provides a completely repeatable and accurate way of measuring either neutrons flux or dose. The experimental results show a total accuracy rate of 96.7% for the true positive tracks and true negative tracks detected by our new algorithm against the current method, which uses computer vision followed by manual revision. This algorithm is now in the process of calibration for both alpha-particles detection and fast neutron spectrometry classification and is expected to be very useful in analyzing results of proton-boron11 fusion experiments. Being fully automatic, the new algorithm will enhance the quality assurance and effectiveness of external dosimetry, will lower the uncertainty for the reported dose measurements, and might also enable lowering the system’s detection threshold.

Reviewing therapy with radioisotopes for pain bone metastasis and its possible evolution

Introduction: The therapy with radioisotopes is widely used, its beginnings were focused on thyroid pathologies treatments. Over the years, the radiopharmaceuticals and/or radioisotopes have had their usage increased, to be used on painful bone metastasis. Material and Methods: A bibliographic search was conducted in the major health Science basis to evaluate what the therapies have to offer for patients in this condition. Results: Currently there are only two available materials in Brazil, the Sm153 that is national production, and Ra223, that is imported. Outside Brazil we can find a variety of materials that have already been approved by the Sanitary Organization in other countries, even though we are not authorized to use them due to Brazilian Regulation and production issues. Conclusion: Besides the diversity of materials that could be used, dosimetry systems must be implemented in order to have a more efficient treatment and to have an accurate administrated activities to patients. &#x0D;

Global and spatial dosimetric characteristics of N-vinylpyrrolidone-based polymer gel dosimeters as a function of medium-term post-preparation and post-irradiation time

It is useful in practice to know the best time intervals between gel preparation, irradiation and imaging for optimal dosimetric response. Knowing how long after preparation and/or irradiation a gel dosimeter can still produce reliable results is also practically helpful. This study aimed to answer these two important but little-investigated questions for normoxic N-vinylpyrrolidone-based polymer gel dosimeters (VIPET) during a nine-day time period. We evaluated the global dose response, reproducibility and high-dose-gradient spatial integrity of this gel dosimetry system for up to 6 Gy dose and assessed the medium-term post-preparation and post-irradiation stability of these key properties with relatively short time intervals of 3 days. After synthesis, several batches of VIPET vials were irradiated with 6 MV photon beams and imaged on a 3 T magnetic resonance imaging (MRI) scanner in different time and dose schemes and were subsequently analysed. Statistical analysis of the experimental data showed acceptable relative dosimetric characteristics in terms of dose sensitivity, offset (R0) values, and linearity of synthesized gel over the course of a nine-day post-preparation and post-irradiation time. The results showed reasonably good reproducibility of dose sensitivity (standard error of measurement, SEM: 0.009) and R0 value (SEM: 0.023). Further, the measurements indicated satisfactory spatial stability of relative dose distribution in high-dose-gradient regions throughout the nine-day studied period (variations in beam penumbra widths and off-axis positions being typically less than 1 mm). These findings provide further evidence to the suitability of the VIPET gel for practical three-dimensional dosimetry in clinical settings such as modern radiotherapy.