In order to explore a dose distribution verification procedure of intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and establish its evaluation criteria, we performed 35 two-dimensio...In order to explore a dose distribution verification procedure of intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and establish its evaluation criteria, we performed 35 two-dimensional (2D) patient-specific IMRT verifications over the year i006. The percent of pixels passing 7 and the normalized agreement test (NAT) index were mainly used to represent the agreement between the measured and computed dose distributions with three criteria (2%/2 mm, 3%/3 mm and 5%/3 mm) as recommended in the literature. The results were that all cases passed through verifications with three criteria except that the NAT index of one case was beyond the limitation, and the three tolerance levels of 2%/2mm, 3%/3 mm and 5%/3 mm produced similar clinical verification results but led to different percent of pixels passing Y and NAT index. Our data showed that the percent of pixels passing y and the NAT index were complementary to evaluate future IMRT verifications as two significant metrics. Due to the influence of the noise and the trait of the software, we considered an IMRT plan as acceptable in case of the percent ofpixels passing y 〉95% and the NAT index 〈5 with the 5%/3 mm criteria for IMRT patient-specific quality assurance (QA).展开更多
Purpose: To test the concept of Statistical Process Control (SPC) as a Quality Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal Radiotherapy (3D-CRT) ...Purpose: To test the concept of Statistical Process Control (SPC) as a Quality Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal Radiotherapy (3D-CRT) treatment of cervical cancer. Materials and Methods: A study of QA verification of target doses of 198 cervical cancer patients undergoing External Beam Radiotherapy (EBRT) treatments at two different cancer treatment centers in Kenya was conducted. The target doses were determined from measured entrance doses by the diode in vivo dosimetry. Process Behavior Charts (PBC) developed by SPC were applied for setting Action Thresholds (AT) on the target doses. The AT set was then proposed as QA limits for acceptance or rejection of verified target doses overtime of the EBRT process. Result and Discussion: Target doses for the 198 patients were calculated and SPC applied to test whether the action limits set by the Process Behavior Charts could be applied as QA for verified doses in EBRT. Results for the two sub-groups of n = 3 and n = 4 that were tested produced action thresholds which are within clinical dose specifications for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. Conclusion: Action thresholds set by SPC were within the clinical dose specification of ±5% uncertainty for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. So the concept of SPC could be applied in setting QA action limits for dose verifications in EBRT.展开更多
<strong>Purpose: </strong><span><span style="font-family:""><span style="font-family:Verdana;">Verified the delivered dose distribution of lung cancer Stereotacti...<strong>Purpose: </strong><span><span style="font-family:""><span style="font-family:Verdana;">Verified the delivered dose distribution of lung cancer Stereotactic </span><span><span style="font-family:Verdana;">Body Radiotherapy (SBRT) using the cone-beam CT images. </span><b><span style="font-family:Verdana;">Methods:</span></b></span><b> </b><span style="font-family:Verdana;">Twenty </span><span style="font-family:Verdana;">lung cancer patients </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">who </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">underwent SBRT with 100 CBCT images were</span></span><span><span style="font-family:""> <span style="font-family:Verdana;">enrolled in this study. Delivered dose distributions were recalculated on</span><span style="font-family:Verdana;"> CBCT images with </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span><span><span style="font-family:""><span style="font-family:Verdana;">deformed and non-deformed metho</span><span style="font-family:Verdana;">d</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span><span><span style="font-family:""><span style="font-family:Verdana;">, respectively. The </span><span style="font-family:Verdana;">planned and delivered dose distributions were compared using the</span><span style="font-family:Verdana;"> dose-volume histograms. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The delivered target coverage (V100) per patient inside target volume deviated on average were 0.83% ± 0.86% and 1.38% ±</span></span></span><span><span style="font-family:""> </span></span><span><span style="font-family:""><span style="font-family:Verdana;">1.40% for Pct </span><i><span style="font-family:Verdana;">vs</span></i><span style="font-family:Verdana;">. Pcbct and Pct </span><i><span style="font-family:Verdana;">vs</span></i><span style="font-family:Verdana;">. Pdcbct, respectively. The Conformity Index (CI) and Gradient Index (GI) showed a good agreement among the plans. For the critical organs, only minor differences were observed between the planned dose and </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span><span><span style="font-family:""><span style="font-family:Verdana;">delivered dose. </span><b><span style="font-family:Verdana;">Conclusions: </span></b><span style="font-family:Verdana;">CBCT images were </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">useful tool for setup and dose deliver</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">y</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"> verification for lung cancer patients </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">who </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">underwent SBRT.</span></span>展开更多
In this paper we analyze the results of dose map verifications for patient’s IMRT (Intensity-modulated radiation therapy) plans and study the factors that may influence the accuracy of verification. MapCHECK, a two-d...In this paper we analyze the results of dose map verifications for patient’s IMRT (Intensity-modulated radiation therapy) plans and study the factors that may influence the accuracy of verification. MapCHECK, a two-dimensional diode array, was used to measure the dose maps for 1242 plans (14540 fields) from May 2004 to August 2008. The plans were designed with Pinnacle3 planning system. The passing rate of beams was determined when the acceptance criterion was 2%/2 mm, 3%/3 mm and 4%/4 mm. And the data with 3%/3 mm criteria was analyzed in more detail. The considered factors were beam modeling, optimization mode and treatment site. The median passing rate of total fields was 93.5%, 98.8%, and 100% when the acceptance criterion was 2%/2 mm, 3%/3 mm and 4%/4 mm, and the interquartile range were 11.1%, 3.8%, and 1.3%, respectively. The results of direct machine parameter optimization (DMPO) planning mode was better than those of multiple-step mode and beam modeling of new accelerators was better than that of old accelerators. These indicate that beam modeling is the key point of improving passing rate of IMRT verification and the influence of treatment site was little. The factors, the total number of segments, minimum area of segments and minimum monitor unit (MU) of segments, also influence the dosimetric accuracy of IMRT plan verification.展开更多
With the continuous development of science and technolog ies in China,radiotherapy technology in medical field has been very significant ly developing,and intensity modulated radiation therapy(IMRT)technology has been...With the continuous development of science and technolog ies in China,radiotherapy technology in medical field has been very significant ly developing,and intensity modulated radiation therapy(IMRT)technology has been the most widely used.This paper first introduces the components and types of two-dimensional matrix detector,two-dimensional ionization chamber matrix detector and two-dimensional semiconductor matrix detector,then analyzes the dosimetric characteristics of the two-dimensional matrix detector.In the end,the various applications of the two-dimensional matrix detector are analyzed and discussed in detail.The paper aims to promote the two-dimensional matrix detector’s development in the field of radiotherapy in China.展开更多
Compton camera-based prompt gamma(PG) imaging has been proposed for range verification during proton therapy. However, a deviation between the PG and dose distributions, as well as the difference between the reconstru...Compton camera-based prompt gamma(PG) imaging has been proposed for range verification during proton therapy. However, a deviation between the PG and dose distributions, as well as the difference between the reconstructed PG and exact values, limit the effectiveness of the approach in accurate range monitoring during clinical applications. The aim of the study was to realize a PG-based dose reconstruction with a Compton camera, thereby further improving the prediction accuracy of in vivo range verification and providing a novel method for beam monitoring during proton therapy. In this paper, we present an approach based on a subset-driven origin ensemble with resolution recovery and a double evolutionary algorithm to reconstruct the dose depth profile(DDP) from the gamma events obtained by a cadmium-zinc-telluride Compton camera with limited position and energy resolution. Simulations of proton pencil beams with clinical particle rate irradiating phantoms made of different materials and the CT-based thoracic phantom were used to evaluate the feasibility of the proposed method. The results show that for the monoenergetic proton pencil beam irradiating homogeneous-material box phantom,the accuracy of the reconstructed DDP was within 0.3 mm for range prediction and within 5.2% for dose prediction. In particular, for 1.6-Gy irradiation in the therapy simulation of thoracic tumors, the range deviation of the reconstructed spreadout Bragg peak was within 0.8 mm, and the relative dose deviation in the peak area was less than 7% compared to the exact values. The results demonstrate the potential and feasibility of the proposed method in future Compton-based accurate dose reconstruction and range verification during proton therapy.展开更多
Purpose: We performed both, dosimetric and positional accuracy verification of dynamic tumor tracking (DTT) intensity modulated radiation therapy (IMRT), with the Vero4DRT system using a moving phantom (QUASAR respira...Purpose: We performed both, dosimetric and positional accuracy verification of dynamic tumor tracking (DTT) intensity modulated radiation therapy (IMRT), with the Vero4DRT system using a moving phantom (QUASAR respiratory motion platform;QUASAR phantom) and system log files. Methods: The QUASAR phantom was placed on a treatment couch. Measurement of the point dose and dose distribution was performed for conventional IMRT, with the QUASAR phantom static and moving;for DTT IMRT, this was performed with the phantom moving for pyramid shaped, prostate, paranasal sinus, and pancreas targets. The QUASAR phantom was driven by a sinusoidal signal in the superior-inferior direction. Furthermore, predicted positional errors induced by the Vero4DRT system and mechanical positional errors of the gimbal head, were calculated using the system log files. Results and Conclusion: For DTT IMRT, the dose at the evaluation point was within 3% compared with the verification plan, and the dose distribution in the passing rates of γ was 97.9%, with the criteria of 3% dose and 3 mm distance to agreement. The position error calculated from the log files was within 2 mm, suggesting the feasibility of employing DTT IMRT with high accuracy using the Vero4DRT system.展开更多
Objective:To test the basic dosimetry characteristics of a new high-resolution matrix and to perform a preliminary study on the three-dimensional(3D)dose verification of intensity-modulated treatment(IMRT).Methods:The...Objective:To test the basic dosimetry characteristics of a new high-resolution matrix and to perform a preliminary study on the three-dimensional(3D)dose verification of intensity-modulated treatment(IMRT).Methods:The dosimetry characteristics of the new matrix were investigated,including repeatability,dose-rate response,and dose linearity.Twenty cases of nasopharyngeal carcinoma(NPC)and 20 cases with lung cancer were randomly selected for IMRT plans,and the novel matrix was employed for 3D dose verification.The measured results were evaluated using the gamma passing rate(GPR)and dose volume histogram(DVH).The action limit(AL)and tolerance limit(TL)of the target volume and each organ at risk(OAR)were calculated with reference to the American Association of Physicists in Medicine(AAPM)TG218 report.Results:The matrix performed well for all dosimetry characteristic tests,with a deviation of<1%.The average GPRs of the body were(99.32±0.32)%,(98.36±0.59)%,and(96.27±1.20)%for NPC,and(99.17±0.74)%,(98.09±1.33)%,and(95.83±2.22)%for lung cancer at the gamma standards of 3%/3 mm,3%/2 mm,and 2%/2 mm.The average GPRs difference between the head-neck and thorax-abdomen plans were<1%for the same gamma standard.For both the target volumes and OARs,the average GPRs were>90%under the relatively strict standard of 2%/2 mm.The DVH showed that the measurement results of D_(98) and D_(95) for the target volumes were slightly lower and D_(2) were higher than those of treatment planning system(TPS)(P<0.01).In addition,with the same standard,there may be significant differences in the values of AL and TL between different structures for target volumes and OARs,especially small-volume OARs such as the chiasma and optic nerve-L.Conclusions:The new matrix showed good dosimetry characteristics and can be effectively applied to the treatment planning dose verification of the head-neck and lung cancer.Further research is needed to establish how to analyze the GPR and DVH of the target volume and OARs,and to determine more precise dose verification standards combined with the parameters of AL and TL to better guide 3D dose verification in clinic.展开更多
目的利用Compass三维验证系统对乳腺癌保乳术后调强放射治疗计划进行剂量验证,研究其影响因素并进行分类分析。方法选择乳腺癌保乳放射治疗女性患者20例,年龄45~74岁,中位年龄59岁;侧别,左侧10例,右侧10例。用Compass系统进行计划剂量验...目的利用Compass三维验证系统对乳腺癌保乳术后调强放射治疗计划进行剂量验证,研究其影响因素并进行分类分析。方法选择乳腺癌保乳放射治疗女性患者20例,年龄45~74岁,中位年龄59岁;侧别,左侧10例,右侧10例。用Compass系统进行计划剂量验证,包括独立核算验证和实测重建剂量验证;将Monaco计划系统蒙卡算法计算的剂量(MCD)、Compass卷积/超分割算法独立核算剂量(CCD)和Compass实测重建剂量(CRD)三者之间两两剂量验证结果进行两两比较(CCD-MCD、CRD-CCD、CRD-MCD),比较参数包括靶区剂量最大限值10%生成区域的γ结果及剂量体积直方图(DVH)结果。结果CRD-MCD与CRD-CCD的γ通过率和平均γ值差异均有统计学意义[(95.23±2.38)%vs(96.33±2.72)%、(94.78±2.56)%vs(95.97±2.95)%、0.41±0.04 vs 0.37±0.04、0.42±0.04 vs 0.38±0.04。P<0.05],CRD-MCD与CCD-MCD的γ通过率和平均γ值差异也均有统计学意义[(95.23±2.38)%vs(99.29±0.46)%、(94.78±2.56)%vs(99.26±0.46)%、0.41±0.04 vs 0.26±0.03、0.42±0.04 vs 0.27±0.03。P<0.05],CRD-CCD与CCD-MCD的γ通过率和平均γ值差异也均有统计学意义[(96.33±2.72)%vs(99.29±0.46)%、(95.97±2.95)%vs(99.26±0.46)%、0.37±0.04 vs 0.26±0.03、0.38±0.04 vs 0.27±0.03。P<0.05]。计划肿瘤靶区(PGTV)的D_(98%)和计划靶区(PTV)的D_(mean)、健侧乳腺的D_(mean)、V5和患侧肺的V20、V30的剂量体积相对偏差在CRD-MCD与CRD-CCD比较,差异有统计学意义[(2.01±1.27)%vs(2.60±1.05)%、(2.84±0.55)%vs(2.55±0.71)%、(-11.15±7.87)%vs(-18.29±7.91)%、(-1.45±5.45)%vs(-2.76±3.83)%、(-0.85±0.36)%vs(-0.65±0.23)%、(-0.56±0.37)%vs(-0.38±0.27)%。P<0.05]。PGTV的D98%、D_(2%)、D_(mean),PTV的D_(98%)、D_(2%)、D_(mean),心脏的D_(mean)、健侧乳腺的D_(mean)、V_(5),健侧肺的V_(5)和患侧肺的V_(5)、V_(20)、V_(30)的剂量体积相对偏差在CRD-MCD与CCD-MCD比较,差异均有统计学意义[(2.01±1.27)%vs(-0.51±0.54)%、(2.86±1.22)%vs(-0.002±0.92)%、(2.63±0.75)%vs(-0.19±0.40)%、(2.17±0.82)%vs(0.38±1.01)%、(2.81±0.95)%vs(-0.17±0.70)%、(2.84±0.55)%vs(0.29±0.43)%、(-17.39±7.79)%vs(0.87±3.30)%、(-11.15±7.87)%vs(9.27±4.87)%、(-1.45±5.45)%vs(2.01±1.30)%、(-0.24±0.80)%vs(0.01±0.04)%、(-4.60±0.87)%vs(0.27±0.59)%、(-0.85±0.36)%vs(-0.21±0.21)%、(-0.56±0.37)%vs(-0.22±1.34)%。P<0.05]。PGTV的D_(98%)、D_(2%)、D_(mean),PTV的D_(98%)、D_(2%)、D_(mean),心脏的D_(mean)、健侧乳腺的D_(mean)、V_(5),健侧肺的V_(5)和患侧肺的V5、V20、V30的剂量体积相对偏差在CRD-CCD与CCD-MCD比较,差异均有统计学意义[(2.60±1.05)%vs(-0.51±0.54)%、(2.88±1.12)%vs(-0.002±0.92)%、(2.83±0.68)%vs(-0.19±0.40)%、(1.81±0.90)%vs(0.38±1.01)%、(2.87±0.82)%vs(-0.17±0.70)%、(2.55±0.71)%vs(0.29±0.43)%、(-18.10±7.40)%vs(0.87±3.30)%、(-18.29±7.91)%vs(9.27±4.81)%、(-2.76±3.83)%vs(2.01±1.30)%、(-0.25±0.81)%vs(0.01±0.04)%、(-4.90±1.03)%vs(0.27±0.59)%、(-0.65±0.23)%vs(-0.21±0.21)%、(0.38±0.27)%vs(-0.22±1.34)%。P<0.05]。结论不同算法在高剂量区、低剂量区和肺等组织密度比较大或者含空腔的组织中计算精度偏差更加显著;机器的稳定性状态对剂量差异亦有影响。展开更多
A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The E...A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The EPID-based incident fluence conversion method deconvolves EPID images to the primary response distribution based on measured lateral scatter kernels in the EPID detector using Conjugate Gradient algorithm.The primary response is converted to the incident fluence based on measured fluence conversion matrix which corrects for off-axis position dependence of the a-Si EPID response and the "horn" beam profile caused by flatting filter. To verify feasibility and accuracy of this method, square fields of various sizes and two IMRT plans were delivered. The dose distributions computed based on EPID-derived incident fluence were compared with the measurement data. For all square field sizes except the smallest field(2 cm), the mean dose differences in cross-line dose profiles were within 1% excluding the penumbra region, and gamma passing percentages with a 2%/2 mm criterion were about 99%. For two IMRT plans, the least gamma passing percentage for all eight IMRT fields was 98.14% with 2%/3 mm criteria. It can be concluded that our direct EPID-based incident fluence conversion method is accurate and capable of being applied to pretreatment dose verification in clinical routines.展开更多
Background: The delivered dose has to be checked and verified with planned dose since precise and accurate dose delivery is essential in Brachytherapy. Sources of uncertainty during Brachytherapy are intra-fraction, i...Background: The delivered dose has to be checked and verified with planned dose since precise and accurate dose delivery is essential in Brachytherapy. Sources of uncertainty during Brachytherapy are intra-fraction, inter-fraction and inter-application variations. In-vivo dosimetry is the direct method to monitor the radiation dose delivered to a patient during radiotherapy. In this study, assessment of the inter-fraction and intra-fraction variations in the interstitial Brachytherapy was done with microMOSFET. Aim: To analyze the inter-fraction variations in dose delivery during interstitial HDR Brachytherapy and to compare the measured point dose with the TPS-calculated point dose, intra-fraction variation, using the microMOSFET in-vivo dosimeter. Materials and Methods: From May 2014 to February 2016, 22 patients with Head and Neck cancers and 8 patients with Soft-Tissue Sarcomas (STS) were selected for this study. All these patients underwent CT imaging more than 24 hours after the application. Brachyvision 3DTPS and GammaMed Plus iX HDR unit were used for treatments. MicroMOSFET in-vivo dosimeter after calibration was used for the measurements of dose inside the treated volume. Intra & Inter-fraction variations were analyzed and reported. Results: The SD of inter-fraction variation among 22 Head & Neck patients ranges from 2.14% to 14.26%. Minimum & maximum dose variation with first fraction dose of patients ranged from -22.33% to +26.71% and the mean doses were -6.42% to +19.76%. Differences of TPS dose and microMOSFET measured first fraction dose, intra-fraction variation, ranged from -12.36% to +5.05%. The SD of inter-fraction variation for 8 STS patients was from 2.81% to 14.43%. Minimum and maximum doses vary from -38.72% to +25.74% and mean dose varies from -21.5% to +12.53%. Differences of point doses of TPS and measured, intra-fraction variation, were from -5.86% to 4.88%. Conclusions: MicroMOSFET has the potential to minimize the gross errors during multi-fractionated Interstitial Brachytherapy. Edema, applicator displacements and placement of microMOSFET are the main influencing factors for inter-fraction uncertainty in dose delivery. Re-planning with re-simulated images should be considered whenever the microMOSFET readings vary more than ±10% of the planned dose inside the CTV measured in two successive fractions.展开更多
文摘In order to explore a dose distribution verification procedure of intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and establish its evaluation criteria, we performed 35 two-dimensional (2D) patient-specific IMRT verifications over the year i006. The percent of pixels passing 7 and the normalized agreement test (NAT) index were mainly used to represent the agreement between the measured and computed dose distributions with three criteria (2%/2 mm, 3%/3 mm and 5%/3 mm) as recommended in the literature. The results were that all cases passed through verifications with three criteria except that the NAT index of one case was beyond the limitation, and the three tolerance levels of 2%/2mm, 3%/3 mm and 5%/3 mm produced similar clinical verification results but led to different percent of pixels passing Y and NAT index. Our data showed that the percent of pixels passing y and the NAT index were complementary to evaluate future IMRT verifications as two significant metrics. Due to the influence of the noise and the trait of the software, we considered an IMRT plan as acceptable in case of the percent ofpixels passing y 〉95% and the NAT index 〈5 with the 5%/3 mm criteria for IMRT patient-specific quality assurance (QA).
文摘Purpose: To test the concept of Statistical Process Control (SPC) as a Quality Assurance (QA) procedure for dose verifications in external beam radiation therapy in conventional and 3D Conformal Radiotherapy (3D-CRT) treatment of cervical cancer. Materials and Methods: A study of QA verification of target doses of 198 cervical cancer patients undergoing External Beam Radiotherapy (EBRT) treatments at two different cancer treatment centers in Kenya was conducted. The target doses were determined from measured entrance doses by the diode in vivo dosimetry. Process Behavior Charts (PBC) developed by SPC were applied for setting Action Thresholds (AT) on the target doses. The AT set was then proposed as QA limits for acceptance or rejection of verified target doses overtime of the EBRT process. Result and Discussion: Target doses for the 198 patients were calculated and SPC applied to test whether the action limits set by the Process Behavior Charts could be applied as QA for verified doses in EBRT. Results for the two sub-groups of n = 3 and n = 4 that were tested produced action thresholds which are within clinical dose specifications for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. Conclusion: Action thresholds set by SPC were within the clinical dose specification of ±5% uncertainty for both conventional AP/PA and 3D-CRT EBRT treatment techniques for cervical cancer. So the concept of SPC could be applied in setting QA action limits for dose verifications in EBRT.
文摘<strong>Purpose: </strong><span><span style="font-family:""><span style="font-family:Verdana;">Verified the delivered dose distribution of lung cancer Stereotactic </span><span><span style="font-family:Verdana;">Body Radiotherapy (SBRT) using the cone-beam CT images. </span><b><span style="font-family:Verdana;">Methods:</span></b></span><b> </b><span style="font-family:Verdana;">Twenty </span><span style="font-family:Verdana;">lung cancer patients </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">who </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">underwent SBRT with 100 CBCT images were</span></span><span><span style="font-family:""> <span style="font-family:Verdana;">enrolled in this study. Delivered dose distributions were recalculated on</span><span style="font-family:Verdana;"> CBCT images with </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span><span><span style="font-family:""><span style="font-family:Verdana;">deformed and non-deformed metho</span><span style="font-family:Verdana;">d</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span><span><span style="font-family:""><span style="font-family:Verdana;">, respectively. The </span><span style="font-family:Verdana;">planned and delivered dose distributions were compared using the</span><span style="font-family:Verdana;"> dose-volume histograms. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The delivered target coverage (V100) per patient inside target volume deviated on average were 0.83% ± 0.86% and 1.38% ±</span></span></span><span><span style="font-family:""> </span></span><span><span style="font-family:""><span style="font-family:Verdana;">1.40% for Pct </span><i><span style="font-family:Verdana;">vs</span></i><span style="font-family:Verdana;">. Pcbct and Pct </span><i><span style="font-family:Verdana;">vs</span></i><span style="font-family:Verdana;">. Pdcbct, respectively. The Conformity Index (CI) and Gradient Index (GI) showed a good agreement among the plans. For the critical organs, only minor differences were observed between the planned dose and </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span><span><span style="font-family:""><span style="font-family:Verdana;">delivered dose. </span><b><span style="font-family:Verdana;">Conclusions: </span></b><span style="font-family:Verdana;">CBCT images were </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">a </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">useful tool for setup and dose deliver</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">y</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"> verification for lung cancer patients </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">who </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">underwent SBRT.</span></span>
文摘In this paper we analyze the results of dose map verifications for patient’s IMRT (Intensity-modulated radiation therapy) plans and study the factors that may influence the accuracy of verification. MapCHECK, a two-dimensional diode array, was used to measure the dose maps for 1242 plans (14540 fields) from May 2004 to August 2008. The plans were designed with Pinnacle3 planning system. The passing rate of beams was determined when the acceptance criterion was 2%/2 mm, 3%/3 mm and 4%/4 mm. And the data with 3%/3 mm criteria was analyzed in more detail. The considered factors were beam modeling, optimization mode and treatment site. The median passing rate of total fields was 93.5%, 98.8%, and 100% when the acceptance criterion was 2%/2 mm, 3%/3 mm and 4%/4 mm, and the interquartile range were 11.1%, 3.8%, and 1.3%, respectively. The results of direct machine parameter optimization (DMPO) planning mode was better than those of multiple-step mode and beam modeling of new accelerators was better than that of old accelerators. These indicate that beam modeling is the key point of improving passing rate of IMRT verification and the influence of treatment site was little. The factors, the total number of segments, minimum area of segments and minimum monitor unit (MU) of segments, also influence the dosimetric accuracy of IMRT plan verification.
文摘With the continuous development of science and technolog ies in China,radiotherapy technology in medical field has been very significant ly developing,and intensity modulated radiation therapy(IMRT)technology has been the most widely used.This paper first introduces the components and types of two-dimensional matrix detector,two-dimensional ionization chamber matrix detector and two-dimensional semiconductor matrix detector,then analyzes the dosimetric characteristics of the two-dimensional matrix detector.In the end,the various applications of the two-dimensional matrix detector are analyzed and discussed in detail.The paper aims to promote the two-dimensional matrix detector’s development in the field of radiotherapy in China.
基金supported by Natural Science Foundation of Beijing Municipality (Beijing Natural Science Foundation)(No.7191005)。
文摘Compton camera-based prompt gamma(PG) imaging has been proposed for range verification during proton therapy. However, a deviation between the PG and dose distributions, as well as the difference between the reconstructed PG and exact values, limit the effectiveness of the approach in accurate range monitoring during clinical applications. The aim of the study was to realize a PG-based dose reconstruction with a Compton camera, thereby further improving the prediction accuracy of in vivo range verification and providing a novel method for beam monitoring during proton therapy. In this paper, we present an approach based on a subset-driven origin ensemble with resolution recovery and a double evolutionary algorithm to reconstruct the dose depth profile(DDP) from the gamma events obtained by a cadmium-zinc-telluride Compton camera with limited position and energy resolution. Simulations of proton pencil beams with clinical particle rate irradiating phantoms made of different materials and the CT-based thoracic phantom were used to evaluate the feasibility of the proposed method. The results show that for the monoenergetic proton pencil beam irradiating homogeneous-material box phantom,the accuracy of the reconstructed DDP was within 0.3 mm for range prediction and within 5.2% for dose prediction. In particular, for 1.6-Gy irradiation in the therapy simulation of thoracic tumors, the range deviation of the reconstructed spreadout Bragg peak was within 0.8 mm, and the relative dose deviation in the peak area was less than 7% compared to the exact values. The results demonstrate the potential and feasibility of the proposed method in future Compton-based accurate dose reconstruction and range verification during proton therapy.
文摘Purpose: We performed both, dosimetric and positional accuracy verification of dynamic tumor tracking (DTT) intensity modulated radiation therapy (IMRT), with the Vero4DRT system using a moving phantom (QUASAR respiratory motion platform;QUASAR phantom) and system log files. Methods: The QUASAR phantom was placed on a treatment couch. Measurement of the point dose and dose distribution was performed for conventional IMRT, with the QUASAR phantom static and moving;for DTT IMRT, this was performed with the phantom moving for pyramid shaped, prostate, paranasal sinus, and pancreas targets. The QUASAR phantom was driven by a sinusoidal signal in the superior-inferior direction. Furthermore, predicted positional errors induced by the Vero4DRT system and mechanical positional errors of the gimbal head, were calculated using the system log files. Results and Conclusion: For DTT IMRT, the dose at the evaluation point was within 3% compared with the verification plan, and the dose distribution in the passing rates of γ was 97.9%, with the criteria of 3% dose and 3 mm distance to agreement. The position error calculated from the log files was within 2 mm, suggesting the feasibility of employing DTT IMRT with high accuracy using the Vero4DRT system.
基金National Natural Science Foundation of China(12005315)Guangdong Esophageal Cancer Institute Science and Technology Program(M201813).
文摘Objective:To test the basic dosimetry characteristics of a new high-resolution matrix and to perform a preliminary study on the three-dimensional(3D)dose verification of intensity-modulated treatment(IMRT).Methods:The dosimetry characteristics of the new matrix were investigated,including repeatability,dose-rate response,and dose linearity.Twenty cases of nasopharyngeal carcinoma(NPC)and 20 cases with lung cancer were randomly selected for IMRT plans,and the novel matrix was employed for 3D dose verification.The measured results were evaluated using the gamma passing rate(GPR)and dose volume histogram(DVH).The action limit(AL)and tolerance limit(TL)of the target volume and each organ at risk(OAR)were calculated with reference to the American Association of Physicists in Medicine(AAPM)TG218 report.Results:The matrix performed well for all dosimetry characteristic tests,with a deviation of<1%.The average GPRs of the body were(99.32±0.32)%,(98.36±0.59)%,and(96.27±1.20)%for NPC,and(99.17±0.74)%,(98.09±1.33)%,and(95.83±2.22)%for lung cancer at the gamma standards of 3%/3 mm,3%/2 mm,and 2%/2 mm.The average GPRs difference between the head-neck and thorax-abdomen plans were<1%for the same gamma standard.For both the target volumes and OARs,the average GPRs were>90%under the relatively strict standard of 2%/2 mm.The DVH showed that the measurement results of D_(98) and D_(95) for the target volumes were slightly lower and D_(2) were higher than those of treatment planning system(TPS)(P<0.01).In addition,with the same standard,there may be significant differences in the values of AL and TL between different structures for target volumes and OARs,especially small-volume OARs such as the chiasma and optic nerve-L.Conclusions:The new matrix showed good dosimetry characteristics and can be effectively applied to the treatment planning dose verification of the head-neck and lung cancer.Further research is needed to establish how to analyze the GPR and DVH of the target volume and OARs,and to determine more precise dose verification standards combined with the parameters of AL and TL to better guide 3D dose verification in clinic.
文摘目的利用Compass三维验证系统对乳腺癌保乳术后调强放射治疗计划进行剂量验证,研究其影响因素并进行分类分析。方法选择乳腺癌保乳放射治疗女性患者20例,年龄45~74岁,中位年龄59岁;侧别,左侧10例,右侧10例。用Compass系统进行计划剂量验证,包括独立核算验证和实测重建剂量验证;将Monaco计划系统蒙卡算法计算的剂量(MCD)、Compass卷积/超分割算法独立核算剂量(CCD)和Compass实测重建剂量(CRD)三者之间两两剂量验证结果进行两两比较(CCD-MCD、CRD-CCD、CRD-MCD),比较参数包括靶区剂量最大限值10%生成区域的γ结果及剂量体积直方图(DVH)结果。结果CRD-MCD与CRD-CCD的γ通过率和平均γ值差异均有统计学意义[(95.23±2.38)%vs(96.33±2.72)%、(94.78±2.56)%vs(95.97±2.95)%、0.41±0.04 vs 0.37±0.04、0.42±0.04 vs 0.38±0.04。P<0.05],CRD-MCD与CCD-MCD的γ通过率和平均γ值差异也均有统计学意义[(95.23±2.38)%vs(99.29±0.46)%、(94.78±2.56)%vs(99.26±0.46)%、0.41±0.04 vs 0.26±0.03、0.42±0.04 vs 0.27±0.03。P<0.05],CRD-CCD与CCD-MCD的γ通过率和平均γ值差异也均有统计学意义[(96.33±2.72)%vs(99.29±0.46)%、(95.97±2.95)%vs(99.26±0.46)%、0.37±0.04 vs 0.26±0.03、0.38±0.04 vs 0.27±0.03。P<0.05]。计划肿瘤靶区(PGTV)的D_(98%)和计划靶区(PTV)的D_(mean)、健侧乳腺的D_(mean)、V5和患侧肺的V20、V30的剂量体积相对偏差在CRD-MCD与CRD-CCD比较,差异有统计学意义[(2.01±1.27)%vs(2.60±1.05)%、(2.84±0.55)%vs(2.55±0.71)%、(-11.15±7.87)%vs(-18.29±7.91)%、(-1.45±5.45)%vs(-2.76±3.83)%、(-0.85±0.36)%vs(-0.65±0.23)%、(-0.56±0.37)%vs(-0.38±0.27)%。P<0.05]。PGTV的D98%、D_(2%)、D_(mean),PTV的D_(98%)、D_(2%)、D_(mean),心脏的D_(mean)、健侧乳腺的D_(mean)、V_(5),健侧肺的V_(5)和患侧肺的V_(5)、V_(20)、V_(30)的剂量体积相对偏差在CRD-MCD与CCD-MCD比较,差异均有统计学意义[(2.01±1.27)%vs(-0.51±0.54)%、(2.86±1.22)%vs(-0.002±0.92)%、(2.63±0.75)%vs(-0.19±0.40)%、(2.17±0.82)%vs(0.38±1.01)%、(2.81±0.95)%vs(-0.17±0.70)%、(2.84±0.55)%vs(0.29±0.43)%、(-17.39±7.79)%vs(0.87±3.30)%、(-11.15±7.87)%vs(9.27±4.87)%、(-1.45±5.45)%vs(2.01±1.30)%、(-0.24±0.80)%vs(0.01±0.04)%、(-4.60±0.87)%vs(0.27±0.59)%、(-0.85±0.36)%vs(-0.21±0.21)%、(-0.56±0.37)%vs(-0.22±1.34)%。P<0.05]。PGTV的D_(98%)、D_(2%)、D_(mean),PTV的D_(98%)、D_(2%)、D_(mean),心脏的D_(mean)、健侧乳腺的D_(mean)、V_(5),健侧肺的V_(5)和患侧肺的V5、V20、V30的剂量体积相对偏差在CRD-CCD与CCD-MCD比较,差异均有统计学意义[(2.60±1.05)%vs(-0.51±0.54)%、(2.88±1.12)%vs(-0.002±0.92)%、(2.83±0.68)%vs(-0.19±0.40)%、(1.81±0.90)%vs(0.38±1.01)%、(2.87±0.82)%vs(-0.17±0.70)%、(2.55±0.71)%vs(0.29±0.43)%、(-18.10±7.40)%vs(0.87±3.30)%、(-18.29±7.91)%vs(9.27±4.81)%、(-2.76±3.83)%vs(2.01±1.30)%、(-0.25±0.81)%vs(0.01±0.04)%、(-4.90±1.03)%vs(0.27±0.59)%、(-0.65±0.23)%vs(-0.21±0.21)%、(0.38±0.27)%vs(-0.22±1.34)%。P<0.05]。结论不同算法在高剂量区、低剂量区和肺等组织密度比较大或者含空腔的组织中计算精度偏差更加显著;机器的稳定性状态对剂量差异亦有影响。
基金Supported by National Natural Science Foundation of China(No.11305203)Natural Science Foundation of Anhui Province(No.1508085QH180)
文摘A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The EPID-based incident fluence conversion method deconvolves EPID images to the primary response distribution based on measured lateral scatter kernels in the EPID detector using Conjugate Gradient algorithm.The primary response is converted to the incident fluence based on measured fluence conversion matrix which corrects for off-axis position dependence of the a-Si EPID response and the "horn" beam profile caused by flatting filter. To verify feasibility and accuracy of this method, square fields of various sizes and two IMRT plans were delivered. The dose distributions computed based on EPID-derived incident fluence were compared with the measurement data. For all square field sizes except the smallest field(2 cm), the mean dose differences in cross-line dose profiles were within 1% excluding the penumbra region, and gamma passing percentages with a 2%/2 mm criterion were about 99%. For two IMRT plans, the least gamma passing percentage for all eight IMRT fields was 98.14% with 2%/3 mm criteria. It can be concluded that our direct EPID-based incident fluence conversion method is accurate and capable of being applied to pretreatment dose verification in clinical routines.
文摘Background: The delivered dose has to be checked and verified with planned dose since precise and accurate dose delivery is essential in Brachytherapy. Sources of uncertainty during Brachytherapy are intra-fraction, inter-fraction and inter-application variations. In-vivo dosimetry is the direct method to monitor the radiation dose delivered to a patient during radiotherapy. In this study, assessment of the inter-fraction and intra-fraction variations in the interstitial Brachytherapy was done with microMOSFET. Aim: To analyze the inter-fraction variations in dose delivery during interstitial HDR Brachytherapy and to compare the measured point dose with the TPS-calculated point dose, intra-fraction variation, using the microMOSFET in-vivo dosimeter. Materials and Methods: From May 2014 to February 2016, 22 patients with Head and Neck cancers and 8 patients with Soft-Tissue Sarcomas (STS) were selected for this study. All these patients underwent CT imaging more than 24 hours after the application. Brachyvision 3DTPS and GammaMed Plus iX HDR unit were used for treatments. MicroMOSFET in-vivo dosimeter after calibration was used for the measurements of dose inside the treated volume. Intra & Inter-fraction variations were analyzed and reported. Results: The SD of inter-fraction variation among 22 Head & Neck patients ranges from 2.14% to 14.26%. Minimum & maximum dose variation with first fraction dose of patients ranged from -22.33% to +26.71% and the mean doses were -6.42% to +19.76%. Differences of TPS dose and microMOSFET measured first fraction dose, intra-fraction variation, ranged from -12.36% to +5.05%. The SD of inter-fraction variation for 8 STS patients was from 2.81% to 14.43%. Minimum and maximum doses vary from -38.72% to +25.74% and mean dose varies from -21.5% to +12.53%. Differences of point doses of TPS and measured, intra-fraction variation, were from -5.86% to 4.88%. Conclusions: MicroMOSFET has the potential to minimize the gross errors during multi-fractionated Interstitial Brachytherapy. Edema, applicator displacements and placement of microMOSFET are the main influencing factors for inter-fraction uncertainty in dose delivery. Re-planning with re-simulated images should be considered whenever the microMOSFET readings vary more than ±10% of the planned dose inside the CTV measured in two successive fractions.