Dosimetric study Dotaz Zobrazit nápovědu
AIM: To evaluate the treatment plans of 3D image-guided brachytherapy (BT) and stereotactic robotic radiotherapy with online image guidance - CyberKnife (CK) in patients with locally advanced cervix cancer. METHODS AND MATERIALS: Ten pairs of plans for patients with locally advanced inoperable cervical cancer were created using MR based 3D brachytherapy and stereotaxis CK. The dose that covers 98% of the target volume (HR CTV D98) was taken as a reference and other parameters were compared. RESULTS: Of the ten studied cases, the dose from D100 GTV was comparable for both devices, on average, the BT GTV D90 was 10-20% higher than for CK. The HR CTV D90 was higher for CK with an average difference of 10-20%, but only fifteen percent of HR CTV (the peripheral part) received a higher dose from CK, while 85% of the target volume received higher doses from BT. We found a significant organ-sparing effect of CK compared to brachytherapy (20-30% lower doses in 0.1 cm(3), 1 cm(3), and 2 cm(3)). CONCLUSION: BT remains to be the best method for dose escalation. Due to the significant organ-sparing effect of CK, patients that are not candidates for BT could benefit from stereotaxis more than from classical external beam radiotherapy.
- Klíčová slova
- Brachytherapy, Cervix carcinoma, CyberKnife, Dosimetric study, Stereotactic radiotherapy,
- Publikační typ
- časopisecké články MeSH
- Klíčová slova
- GONADS/radiation effects *, RADIOTHERAPY *,
- MeSH
- gonády účinky záření MeSH
- lidé MeSH
- radiometrie * MeSH
- radioterapie * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Introduction: Within an International Atomic Energy Agency (IAEA) co-ordinated research project (CRP), a remote end-to-end dosimetric quality audit for intensity modulated radiation therapy (IMRT)/ volumetric arc therapy (VMAT) was developed to verify the radiotherapy chain including imaging, treatment planning and dose delivery. The methodology as well as the results obtained in a multicentre pilot study and national trial runs conducted in close cooperation with dosimetry audit networks (DANs) of IAEA Member States are presented.Material and methods: A solid polystyrene phantom containing a dosimetry insert with an irregular solid water planning target volume (PTV) and organ at risk (OAR) was designed for this audit. The insert can be preloaded with radiochromic film and four thermoluminescent dosimeters (TLDs). For the audit, radiotherapy centres were asked to scan the phantom, contour the structures, create an IMRT/VMAT treatment plan and irradiate the phantom. The dose prescription was to deliver 4 Gy to the PTV in two fractions and to limit the OAR dose to a maximum of 2.8 Gy. The TLD measured doses and film measured dose distributions were compared with the TPS calculations.Results: Sixteen hospitals from 13 countries and 64 hospitals from 6 countries participated in the multicenter pilot study and in the national runs, respectively. The TLD results for the PTV were all within ±5% acceptance limit for the multicentre pilot study, whereas for national runs, 17 participants failed to meet this criterion. All measured doses in the OAR were below the treatment planning constraint. The film analysis identified seven plans in national runs below the 90% passing rate gamma criteria.Conclusion: The results proved that the methodology of the IMRT/VMAT dosimetric end-to-end audit was feasible for its intended purpose, i.e., the phantom design and materials were suitable; the phantom was easy to use and it was robust enough for shipment. Most importantly the audit methodology was capable of identifying suboptimal IMRT/VMAT delivery.
- MeSH
- celková dávka radioterapie MeSH
- fantomy radiodiagnostické * MeSH
- jaderná energie MeSH
- kritické orgány * MeSH
- lidé MeSH
- mezinárodní agentury MeSH
- pilotní projekty MeSH
- plánování radioterapie pomocí počítače metody MeSH
- počítačová rentgenová tomografie MeSH
- radiometrie metody normy MeSH
- radioterapie s modulovanou intenzitou metody normy MeSH
- revize kvality lékařské péče metody normy MeSH
- studie proveditelnosti MeSH
- zajištění kvality zdravotní péče MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
BACKGROUND AND PURPOSE: The amino-acid positron emission tomography (PET) tracer 3,4-dihydroxy-6-[18F] fluoro-l-phenylalanine (18F-DOPA) has increased sensitivity for detecting regions of biologically aggressive tumors compared to T1 contrast-enhanced (T1-CE) magnetic resonance imaging (MRI). We performed dosimetric evaluation of treatment plans prepared with and without inclusion of 18F-DOPA-based biological target volume (BTV) evaluating its role in guiding radiotherapy of grade III/IV gliomas. MATERIALS AND METHODS: Eight patients (five T1-CE, three non-contrast-enhancing [NCE]) were included in our study. MRI only-guided anatomic plans and MRI+18FDOPA-PET-guided biologic plans were prepared for each patient, and dosimetric data for target volumes and organs at risk (OAR) were compared. High-dose BTV60Gy was defined as regions with tumor to normal brain (T/N) >2.0, while low-dose BTV51Gy was initially based on T/N >1.3, but refined per Nuclear Medicine expert. RESULTS: For T1-CE tumors, planning target volumes (PTV) were larger than MRI-only anatomic target volumes. Despite increases in size of both gross target volumes and PTV, with volumetric-modulated arc therapy planning, no increase of dose to OAR was observed while maintaining similar target dose coverage. For NCE tumors, MRI+18F-DOPA PET biologic imaging identified a sub-region of the large, T2-FLAIR abnormal signal which may allow a smaller volume to receive the high dose (60 Gy) radiation. CONCLUSIONS: For T1-CE tumors, PTVs were larger than MRI-only anatomic target volumes with no increase of dose to OARs. Therefore, MRI+18F-DOPA PET-based biologic treatment planning appears feasible in patients with high-grade gliomas.
- Klíčová slova
- 18F-DOPA PET, Amino acid PET, PET-guided radiation therapy, Planning study,
- Publikační typ
- časopisecké články MeSH
The Convolution algorithm, implemented in Leksell GammaPlan® ver. Here, 10, is the first algorithm for Leksell Gamma Knife that takes heterogeneities into account and models dose build-up effects close to tissue boundaries. The aim of this study was preliminary comparison of the Convolution and TMR10 algorithms for real clinical cases and dosimetric verification of the algorithms, using measurements in a phantom. A total of 25 patients involved in comparison of the Convolution and TMR10 algorithms were divided into three groups: patients with benign tumors close to heterogeneities, patients with functional disorders, and patients with tumors located far from heterogeneities. Differences were observed especially in the group of patients with tumors close to heterogeneities, where the difference in maximal dose to critical structures for the Convolution algorithm was up to 15% compared to the TMR10 algorithm. Dosimetric verification of the algorithm was performed, using a radiochromic gel dosimeter based on Turnbull blue dye in a special heterogeneous phantom. Relative dose distributions measured with the radiochromic gel dosimeter agreed very well with both the TMR10 and Convolution calculations. We observed small discrepancies in the direction in which the largest inhomogeneity was positioned. Verification results indicated that the Convolution algorithm provides a different dose distribution, especially in regions close to heterogeneities and particularly for lower isodose volumes. However, the results obtained with gamma analyses in the gel dosimetry experiment did not verify the assumption that the Convolution algorithm provides more accurate dose calculation.
- Klíčová slova
- gel dosimetry, stereotactic radiosurgery, verification,
- MeSH
- algoritmy * MeSH
- celková dávka radioterapie MeSH
- fantomy radiodiagnostické * MeSH
- filmová dozimetrie * MeSH
- kritické orgány účinky záření MeSH
- lidé MeSH
- metoda Monte Carlo MeSH
- nádory chirurgie MeSH
- plánování radioterapie pomocí počítače metody MeSH
- radiochirurgie metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
BACKGROUND: Patterns of failure (POF) may provide an alternative quantitative endpoint to overall survival for evaluation of novel chemoradiotherapy regimens with glioblastoma. MATERIALS AND METHODS: POF of 109 newly-diagnosed glioblastoma patients per 2016 WHO classification who received conformal radiotherapy with concomitant and adjuvant temozolomide were reviewed. Seventy-five of those patients also received an investigational chemotherapy agent (everolimus, erlotinib, or vorinostat). Recurrence volumes were defined with MRI contrast enhancement. POF at protocol (POFp), initial (POFi), and RANO (POFRANO) progression timepoints were characterized by the percentage of recurrence volume within the 95% dose region. POFp, POFi, and POFRANO of each patient were categorized (central, non-central, or both). RESULTS: POF of the temozolomide-only control cohort were unchanged (79% central, 12% non-central, and 9% both) across protocol, initial, and RANO progression timepoints. Unlike the temozolomide-only cohort, POF of the collective novel chemotherapy cohort appeared increasingly non-central when comparing POFi with POFp, with a non-central component increasing from 16% to 29% (p = 0.078). POF did not correlate with overall survival or time to progression. CONCLUSION: POF of patients receiving a novel chemotherapy appeared to be influenced by the timepoint of analysis and were increasingly non-central at protocol progression as compared with initial recurrence, suggesting that recurrence originates from the central region. Addition of everolimus and vorinostat appeared to influence POF, despite similar survival outcomes with the temozolomide-only control group. In studies dealing with novel therapeutic agents, robust and properly-timed dosimetric POF analysis may be helpful to evaluate biologic aspects of novel agents.
- Klíčová slova
- Glioblastoma, Glioma, Patterns of failure, Recurrence,
- Publikační typ
- časopisecké články MeSH
The purpose of this study is to evaluate the dosimetric impact of the margin on the multileaf collimator-based dynamic tumor tracking plan. Furthermore, an equivalent setup margin (EM) of the tracking plan was determined according to the gated plan. A 4-dimensional extended cardiac-torso was used to create 9 digital phantom datasets of different tumor diameters (TDs) of 1, 3, and 5 cm and motion ranges (MRs) of 1, 2, and 3 cm. For each dataset, respiratory gating (30% to 70% phase) and tumor tracking treatment plans were prepared using 8-field 3-dimensional conformal radiation therapy by 4-dimensional dose calculation. The total lung V20 was calculated to evaluate the dosimetric impact for each case and to estimate the EM with the same impact on lung V20 obtained with the gating plan with a setup margin of 5 mm. The EMs for {TD = 1 cm, MR = 1 cm}, {TD = 1 cm, MR = 2 cm}, and {TD = 1 cm, MR = 3 cm} were estimated as 5.00, 4.16, and 4.24 mm, respectively. The EMs for {TD = 5 cm, MR = 1 cm}, {TD = 5 cm, MR = 2 cm}, and {TD = 5 cm, MR = 3 cm} were estimated as 4.24 mm, 6.35 mm, and 7.49 mm, respectively. This result showed that with a larger MR, the EM was found to be increased. In addition, with a larger TD, the EM became smaller. Our result showing the EMs provided the desired accuracy for multileaf collimator-based dynamic tumor tracking radiotherapy.
- Klíčová slova
- Dynamic tumor tracking radiotherapy, Four-dimensional dose calculation, Radiotherapy, Setup margin, Stereotactic body radiotherapy,
- MeSH
- celková dávka radioterapie * MeSH
- fantomy radiodiagnostické MeSH
- konformní radioterapie metody MeSH
- lidé MeSH
- nádory plic patologie radioterapie MeSH
- plánování radioterapie pomocí počítače MeSH
- pohyb těles MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
This paper deals with the measurement of ionising radiation emitted in the vertical field of electric discharge generated between the tip and the grounded plate electrode. The generator set-up was for 400 consecutive negative discharges with voltage amplitude 0.9 MV, waveform shape 1.2/50 $\mu $s, discharge energy 80 kJ and electrodes 1 m apart. Thermoluminescent, passive detectors were used to avoid electromagnetic interference from the discharge. The detectors were placed at the electrodes and three vertical positions 1 m from the discharge axis. This work extends a previous study focused on dosimetry in the plane parallel to the ground. This experiment confirmed the presence of a photon/electron component at the electrode tip and 0.5 m vertical position at a distance of 1 m from the discharge axis. In addition, the presence of neutrons was found for new positions in the vertical axis and the ground electrode.
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: Patients with nasopharyngeal cancer are candidates for proton radiotherapy due to large and comprehensive target volumes, and the necessity for sparing of healthy tissues. The aim of this work is to evaluate treatment outcome and toxicity profile of patients treated with proton pencil-beam scanning radiotherapy. MATERIALS AND METHODS: Between Jan 2013 and June 2018, 40 patients were treated for nasopharyngeal cancer (NPC) with IMPT (proton radiotherapy with modulated intensity). Median age was 47 years and the majority of patients had locally advanced tumors (stage 2-8 patients. (20%); stage 3-18 patients (45%); stage 4A-10 patients. (25%); stage 4B-4 patients. (10%). Median of total dose was 74 GyE (70-76 GyE) in 37 fractions (35-38). Bilateral neck irradiation was used in all cases. Concomitant chemotherapy was applied in 34 cases. (85%). Median follow-up time was 24 (1.5-62) months. RESULTS: Two-year overall survival (OS), disease-free survival (DFS), and local control (LC) were 80%, 75%, and 84%, respectively. Acute toxicity was generally mild despite large target volumes and concurrent application of chemotherapy with skin toxicity and dysphagia reported as the most frequent acute side effects. The insertion of a percutaneous endoscopic gastrectomy (PEG) was necessary in four cases (10%). Serious late toxicity (G > 3. RTOG) was observed in two patients (5%) (dysphagia and brain necrosis). CONCLUSION: IMPT for nasopharyngeal cancer patients is feasible with mild acute toxicity. Treatment outcomes are promising despite the high percentage of advanced disease in this group.
- Klíčová slova
- Dosimetry, Nasopharyngeal carcinoma, Pencil-beam scanning, Proton therapy, Toxicity,
- MeSH
- celková dávka radioterapie MeSH
- lidé středního věku MeSH
- lidé MeSH
- nádory nosohltanu * radioterapie MeSH
- následné studie MeSH
- nasofaryngeální karcinom radioterapie MeSH
- protonová terapie * škodlivé účinky MeSH
- protony MeSH
- radioterapie s modulovanou intenzitou škodlivé účinky MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- protony MeSH
