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Item does not contain fulltext, Inhomogeneities in radiotherapy dose distributions covering the vertebrae in children can produce long-term spinal problems, including kyphosis, lordosis, scoliosis, and hypoplasia. In the published literature, many often interrelated variables have been reported to affect the extent of potential radiotherapy damage to the spine. Articles published in the 2D and 3D radiotherapy era instructed radiation oncologists to avoid dose inhomogeneity over growing vertebrae. However, in the present era of highly conformal radiotherapy, steep dose gradients over at-risk structures can be generated and thus less harm is caused to patients. In this report, paediatric radiation oncologists from leading centres in 11 European countries have produced recommendations on how to approach dose coverage for target volumes that are adjacent to vertebrae to minimise the risk of long-term spinal problems. Based on available information, it is advised that homogeneous vertebral radiotherapy doses should be delivered in children who have not yet finished the pubertal growth spurt. If dose fall-off within vertebrae cannot be avoided, acceptable dose gradients for different age groups are detailed here. Vertebral delineation should include all primary ossification centres and growth plates, and therefore include at least the vertebral body and arch. For partial spinal radiotherapy, the number of irradiated vertebrae should be restricted as much as achievable, particularly at the thoracic level in young children (<6 years old). There is a need for multicentre research on vertebral radiotherapy dose distributions for children, but until more valid data become available, these recommendations can provide a basis for daily practice for radiation oncologists who have patients that require vertebral radiotherapy.

Item does not contain fulltext, Inhomogeneities in radiotherapy dose distributions covering the vertebrae in children can produce long-term spinal problems, including kyphosis, lordosis, scoliosis, and hypoplasia. In the published literature, many often interrelated variables have been reported to affect the extent of potential radiotherapy damage to the spine. Articles published in the 2D and 3D radiotherapy era instructed radiation oncologists to avoid dose inhomogeneity over growing vertebrae. However, in the present era of highly conformal radiotherapy, steep dose gradients over at-risk structures can be generated and thus less harm is caused to patients. In this report, paediatric radiation oncologists from leading centres in 11 European countries have produced recommendations on how to approach dose coverage for target volumes that are adjacent to vertebrae to minimise the risk of long-term spinal problems. Based on available information, it is advised that homogeneous vertebral radiotherapy doses should be delivered in children who have not yet finished the pubertal growth spurt. If dose fall-off within vertebrae cannot be avoided, acceptable dose gradients for different age groups are detailed here. Vertebral delineation should include all primary ossification centres and growth plates, and therefore include at least the vertebral body and arch. For partial spinal radiotherapy, the number of irradiated vertebrae should be restricted as much as achievable, particularly at the thoracic level in young children (<6 years old). There is a need for multicentre research on vertebral radiotherapy dose distributions for children, but until more valid data become available, these recommendations can provide a basis for daily practice for radiation oncologists who have patients that require vertebral radiotherapy.

Item does not contain fulltext, Inhomogeneities in radiotherapy dose distributions covering the vertebrae in children can produce long-term spinal problems, including kyphosis, lordosis, scoliosis, and hypoplasia. In the published literature, many often interrelated variables have been reported to affect the extent of potential radiotherapy damage to the spine. Articles published in the 2D and 3D radiotherapy era instructed radiation oncologists to avoid dose inhomogeneity over growing vertebrae. However, in the present era of highly conformal radiotherapy, steep dose gradients over at-risk structures can be generated and thus less harm is caused to patients. In this report, paediatric radiation oncologists from leading centres in 11 European countries have produced recommendations on how to approach dose coverage for target volumes that are adjacent to vertebrae to minimise the risk of long-term spinal problems. Based on available information, it is advised that homogeneous vertebral radiotherapy doses should be delivered in children who have not yet finished the pubertal growth spurt. If dose fall-off within vertebrae cannot be avoided, acceptable dose gradients for different age groups are detailed here. Vertebral delineation should include all primary ossification centres and growth plates, and therefore include at least the vertebral body and arch. For partial spinal radiotherapy, the number of irradiated vertebrae should be restricted as much as achievable, particularly at the thoracic level in young children (<6 years old). There is a need for multicentre research on vertebral radiotherapy dose distributions for children, but until more valid data become available, these recommendations can provide a basis for daily practice for radiation oncologists who have patients that require vertebral radiotherapy.

Background and purpose: Local implementation of plan-specific quality assurance (QA) methods for intensitymodulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) treatment plans may vary because of dissimilarities in procedures, equipment and software. The purpose of this work is detecting possible differences between local QA findings and those of an audit, using the same set of treatment plans. Methods: A pre-defined set of clinical plans was devised and imported in the participating institute’s treatment planning system for dose computation. The dose distribution was measured using an ionisation chamber, radiochromic film and an ionisation chamber array. The centres performed their own QA, which was compared to the audit findings. The agreement/disagreement between the audit and the institute QA results were assessed along with the differences between the dose distributions measured by the audit team and computed by the institute. Results: For the majority of the cases the results of the audit were in agreement with the institute QA findings: ionisation chamber: 92%, array: 88%, film: 76% of the total measurements. In only a few of these cases the evaluated measurements failed for both: ionisation chamber: 2%, array: 4%, film: 0% of the total measurements. Conclusion: Using predefined treatment plans, we found that in approximately 80% of the evaluated measurements the results of local QA of IMRT and VMAT plans were in line with the findings of the audit. However, the percentage of agreement/disagreement depend

Item does not contain fulltext, BACKGROUND AND PURPOSE: The TRENDY trial is an international multi-center phase-II study, randomizing hepatocellular carcinoma (HCC) patients between transarterial chemoembolization (TACE) and stereotactic body radiation therapy (SBRT) with a target dose of 48-54Gy in six fractions. The radiotherapy quality assurance (QA) program, including prospective plan feedback based on automated treatment planning, is described and results are reported. MATERIALS AND METHODS: Scans of a single patient were used as a benchmark case. Contours submitted by nine participating centers were compared with reference contours. The subsequent planning round was based on a single set of contours. A total of 20 plans from participating centers, including 12 from the benchmark case, 5 from a clinical pilot and 3 from the first study patients, were compared to automatically generated VMAT plans. RESULTS: For the submitted liver contours, Dice Similarity Coefficients (DSC) with the reference delineation ranged from 0.925 to 0.954. For the GTV, the DSC varied between 0.721 and 0.876. For the 12 plans on the benchmark case, healthy liver normal-tissue complication probabilities (NTCPs) ranged from 0.2% to 22.2% with little correlation between NCTP and PTV-D95% (R(2)<0.3). Four protocol deviations were detected in the set of 20 treatment plans. Comparison with co-planar autoVMAT QA plans revealed these were due to too high target dose and suboptimal planning. Overall, autoVMAT resulted in an average liver NTCP reduction of 2.2 percent point (range: 16.2 percent point to -1.8 percent point, p=0.03), and lower doses to the healthy liver (p<0.01) and gastrointestinal organs at risk (p<0.001). CONCLUSIONS: Delineation variation resulted in feedback to participating centers. Automated treatment planning can play an important role in clinical trials for prospective plan QA as suboptimal plans were detected.

Item does not contain fulltext, BACKGROUND AND PURPOSE: The TRENDY trial is an international multi-center phase-II study, randomizing hepatocellular carcinoma (HCC) patients between transarterial chemoembolization (TACE) and stereotactic body radiation therapy (SBRT) with a target dose of 48-54Gy in six fractions. The radiotherapy quality assurance (QA) program, including prospective plan feedback based on automated treatment planning, is described and results are reported. MATERIALS AND METHODS: Scans of a single patient were used as a benchmark case. Contours submitted by nine participating centers were compared with reference contours. The subsequent planning round was based on a single set of contours. A total of 20 plans from participating centers, including 12 from the benchmark case, 5 from a clinical pilot and 3 from the first study patients, were compared to automatically generated VMAT plans. RESULTS: For the submitted liver contours, Dice Similarity Coefficients (DSC) with the reference delineation ranged from 0.925 to 0.954. For the GTV, the DSC varied between 0.721 and 0.876. For the 12 plans on the benchmark case, healthy liver normal-tissue complication probabilities (NTCPs) ranged from 0.2% to 22.2% with little correlation between NCTP and PTV-D95% (R(2)<0.3). Four protocol deviations were detected in the set of 20 treatment plans. Comparison with co-planar autoVMAT QA plans revealed these were due to too high target dose and suboptimal planning. Overall, autoVMAT resulted in an average liver NTCP reduction of 2.2 percent point (range: 16.2 percent point to -1.8 percent point, p=0.03), and lower doses to the healthy liver (p<0.01) and gastrointestinal organs at risk (p<0.001). CONCLUSIONS: Delineation variation resulted in feedback to participating centers. Automated treatment planning can play an important role in clinical trials for prospective plan QA as suboptimal plans were detected.

Item does not contain fulltext, BACKGROUND AND PURPOSE: The TRENDY trial is an international multi-center phase-II study, randomizing hepatocellular carcinoma (HCC) patients between transarterial chemoembolization (TACE) and stereotactic body radiation therapy (SBRT) with a target dose of 48-54Gy in six fractions. The radiotherapy quality assurance (QA) program, including prospective plan feedback based on automated treatment planning, is described and results are reported. MATERIALS AND METHODS: Scans of a single patient were used as a benchmark case. Contours submitted by nine participating centers were compared with reference contours. The subsequent planning round was based on a single set of contours. A total of 20 plans from participating centers, including 12 from the benchmark case, 5 from a clinical pilot and 3 from the first study patients, were compared to automatically generated VMAT plans. RESULTS: For the submitted liver contours, Dice Similarity Coefficients (DSC) with the reference delineation ranged from 0.925 to 0.954. For the GTV, the DSC varied between 0.721 and 0.876. For the 12 plans on the benchmark case, healthy liver normal-tissue complication probabilities (NTCPs) ranged from 0.2% to 22.2% with little correlation between NCTP and PTV-D95% (R(2)<0.3). Four protocol deviations were detected in the set of 20 treatment plans. Comparison with co-planar autoVMAT QA plans revealed these were due to too high target dose and suboptimal planning. Overall, autoVMAT resulted in an average liver NTCP reduction of 2.2 percent point (range: 16.2 percent point to -1.8 percent point, p=0.03), and lower doses to the healthy liver (p<0.01) and gastrointestinal organs at risk (p<0.001). CONCLUSIONS: Delineation variation resulted in feedback to participating centers. Automated treatment planning can play an important role in clinical trials for prospective plan QA as suboptimal plans were detected.

Proton therapy offers great potential in cancer treatment compared with the conventional photon therapy. The advantages of the unique physical properties of protons are a reduction of integral dose to critical structures proximal to the target area and less radiation related side effects. There are many cancer related indications that may benefit from the advantages. The challenges in proton therapy are dealing with physical uncertainties that affect the dose distribution, improving the technology to make proton therapy more efficient and proofing the clinical- and cost-effectiveness. This critical review discusses the physical properties, beam production and delivery, cost-effectiveness and the clinical facet of protons including CNS tumours, prostate cancer, left-sided breast cancer, head and neck tumours and Hodgkin’s disease.

Proton therapy offers great potential in cancer treatment compared with the conventional photon therapy. The advantages of the unique physical properties of protons are a reduction of integral dose to critical structures proximal to the target area and less radiation related side effects. There are many cancer related indications that may benefit from the advantages. The challenges in proton therapy are dealing with physical uncertainties that affect the dose distribution, improving the technology to make proton therapy more efficient and proofing the clinical- and cost-effectiveness. This critical review discusses the physical properties, beam production and delivery, cost-effectiveness and the clinical facet of protons including CNS tumours, prostate cancer, left-sided breast cancer, head and neck tumours and Hodgkin’s disease.

A two-dimensional position-sensitive dosimetry system based on a scintillating gas detector is being developed for pre-treatment verification of dose distributions in particle therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two gas electron multiplier (GEM) structures are mounted (Seravalli et al 2008b Med. Phys. Biol. 53 4651–65). Photons emitted by the excited Ar/CF4 gas molecules during the gas multiplication in the GEM holes are detected by a mirror–lens–CCD camera system. The intensity distribution of the measured light spot is proportional to the 2D dose distribution. In this work, we report on the characterization of the scintillating GEM detector in terms of those properties that are of particular importance in relative dose measurements, e.g. response reproducibility, dose dependence, dose rate dependence, spatial and time response, field size dependence, response uniformity. The experiments were performed in a 150 MeV proton beam. We found that the detector response is very stable for measurements performed in succession (? = 0.6%) and its response reproducibility over 2 days is about 5%. The detector response was found to be linear with the dose in the range 0.05–19 Gy. No dose rate effects were observed between 1 and 16 Gy min?1 at the shallow depth of a water phantom and 2 and 38 Gy min?1 at the Bragg peak depth. No field size effects were observed in the range 120–3850 mm2. A signal rise and fall time of 2 ?s was recorded and a spatial response of ?1 mm was measured., Radiation, Radionuclides and Reactors, Applied Sciences

A two-dimensional position-sensitive dosimetry system based on a scintillating gas detector is being developed for pre-treatment verification of dose distributions in particle therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two gas electron multiplier (GEM) structures are mounted (Seravalli et al 2008b Med. Phys. Biol. 53 4651–65). Photons emitted by the excited Ar/CF4 gas molecules during the gas multiplication in the GEM holes are detected by a mirror–lens–CCD camera system. The intensity distribution of the measured light spot is proportional to the 2D dose distribution. In this work, we report on the characterization of the scintillating GEM detector in terms of those properties that are of particular importance in relative dose measurements, e.g. response reproducibility, dose dependence, dose rate dependence, spatial and time response, field size dependence, response uniformity. The experiments were performed in a 150 MeV proton beam. We found that the detector response is very stable for measurements performed in succession (? = 0.6%) and its response reproducibility over 2 days is about 5%. The detector response was found to be linear with the dose in the range 0.05–19 Gy. No dose rate effects were observed between 1 and 16 Gy min?1 at the shallow depth of a water phantom and 2 and 38 Gy min?1 at the Bragg peak depth. No field size effects were observed in the range 120–3850 mm2. A signal rise and fall time of 2 ?s was recorded and a spatial response of ?1 mm was measured., Radiation, Radionuclides and Reactors, Applied Sciences

Applied Sciences

Applied Sciences

The main aim of radiotherapy techniques is to deliver the dose to the target volume while sparing as much as possible the healthy tissue. Dose verifications prior the treatment of the patient are mandatory in order to guarantee high accuracy to the treatment. We have developed a 2D dose imaging system for dose delivery verification in hadron therapy. The system consists of two cascaded Gas Electron Multipliers (GEMs) in an Ar/CF4 scintillating gas mixture. A GEM is a copper clad thin kapton foil with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process light is emitted by the excited Ar/CF4 molecules and detected by a mirror-lens-CCD camera system. The measured 2D light intensity distribution is proportional to the 2D distribution of the energy deposited in the sensitive volume by the hadron beam. When the thickness of a water bellows phantom, mounted upstream the detector, is varied from zero up to beyond the hadron range, a 3D dose distribution can be reconstructed easily. The response of the detector was studied in a proton, alpha and clinical carbon beam. The main result of this work is that the energy dependence of the detector response in high LET (Linear Energy Transfer) beams is quite small compared to state-of-the-art 2D dosimeters with a millimetre resolution. The scintillating GEM detector is a promising device for dose verification, especially in case of high LET beams for checking treatment plans composed of several beam energies. Its fast signal response opens the possibility for online monitoring of a 2D scanning beam as well., Applied Sciences

Applied Sciences

Applied Sciences

The main aim of radiotherapy techniques is to deliver the dose to the target volume while sparing as much as possible the healthy tissue. Dose verifications prior the treatment of the patient are mandatory in order to guarantee high accuracy to the treatment. We have developed a 2D dose imaging system for dose delivery verification in hadron therapy. The system consists of two cascaded Gas Electron Multipliers (GEMs) in an Ar/CF4 scintillating gas mixture. A GEM is a copper clad thin kapton foil with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process light is emitted by the excited Ar/CF4 molecules and detected by a mirror-lens-CCD camera system. The measured 2D light intensity distribution is proportional to the 2D distribution of the energy deposited in the sensitive volume by the hadron beam. When the thickness of a water bellows phantom, mounted upstream the detector, is varied from zero up to beyond the hadron range, a 3D dose distribution can be reconstructed easily. The response of the detector was studied in a proton, alpha and clinical carbon beam. The main result of this work is that the energy dependence of the detector response in high LET (Linear Energy Transfer) beams is quite small compared to state-of-the-art 2D dosimeters with a millimetre resolution. The scintillating GEM detector is a promising device for dose verification, especially in case of high LET beams for checking treatment plans composed of several beam energies. Its fast signal response opens the possibility for online monitoring of a 2D scanning beam as well., Applied Sciences