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Objective:To compare the dosimetric difference between intensity-modulated photon radiaotherapy (IMRT) planning and intensity-modulated proton radiotherapy (IMPT) planning for glioma.Methods:The clinical data of 15 glioma patients who underwent IMRT in ion medical center of the First Affiliated Hospital of USTC from November 2020 to April 2022 were retrospectively analyzed. IMRT planning and IMPT planning were designed for the image of each patient in the therapy planning system. Main dosimetric parameters were compared including plan target volume (PTV), coverage index (CI), dose homogeneity index (HI), and maximal dose (D max) and mean dose (D mean) of organs at risk between both plans. Results:There were no significant differences between IMRT planning and IMPT planning in terms of D max and D mean of PTV1 and PTV2, CI and HI (all P > 0.05). Compared with IMRT planning, brainstem D mean [6.92 GyE (0.09 GyE, 12.58 GyE) vs. 24.41 GyE (2.59 GyE, 34.18 GyE)], left optic nerve D max [0.78 GyE (0.04 GyE, 25.18 GyE) vs. 20.42 GyE (6.38 GyE, 37.17 GyE)], left optic nerve D mean [0.10 GyE (0.01 GyE, 11.63 GyE) vs. 9.74 GyE (2.99 GyE, 20.87 GyE)], right optic nerve D mean [1.57 GyE (0.13 GyE, 14.90 GyE) vs. 14.08 GyE (2.66 GyE, 23.67 GyE)], left len D max [0 GyE (0 GyE, 2.91 GyE) vs. 4.84 GyE (1.42 GyE, 5.48 GyE)], left len D mean [0 GyE (0 GyE, 1.73 GyE) vs. 3.84 GyE (1.25 GyE, 4.30 GyE)], right len D max [0.25 GyE (0.04 GyE, 4.55 GyE) vs. 4.28 GyE (1.58 GyE, 5.84 GyE)], right len D mean [0.16 GyE (0.01 GyE, 1.95 GyE) vs. 3.73 GyE (1.04 GyE, 4.86 GyE)], pituitary D max [6.97 GyE (0.18 GyE, 39.70 GyE) vs. 36.60 GyE (2.74 GyE, 45.19 GyE)], pituitary D mean [1.36 GyE (0.06 GyE, 13.85 GyE) vs. 24.74 GyE (2.42 GyE, 32.80 GyE)], hippocampus D max [5.10 GyE (0.24 GyE, 26.52 GyE) vs. 35.83 GyE (5.03 GyE, 46.11 GyE)], hippocampus D mean [0.36 GyE (0.04 GyE, 25.65 GyE) vs. 18.79 GyE (2.37 GyE, 28.10 GyE)] in IMPT planning were lower, and the differences were statistically significant (all P < 0.05). There were no statistical differences in brainstem D max [51.98 GyE (0.66 GyE, 53.43 GyE) vs. 53.29 GyE (3.87 GyE, 53.48 GyE)], right optic nerve D max [9.60 GyE (0.01 GyE, 43.32 GyE) vs. 25.37 GyE (3.45 GyE, 41.25 GyE)] of both plans (all P > 0.05). Conclusion:In the radiotherapy for glioma, IMRT and IMPT can meet the dose demand in clinic. Furthermore, IMPT planning can protect organs at risk and reduce radiation dose in hippocampus, brainstem, optic nerve, lens and pituitary.
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Objective:Patients are breathing freely during adjuvant proton pencil beam radiotherapy after breast conserving surgery. Fluctuation of the thorax may affect the position of the end of the proton beam flow, which needs to be precisely evaluated on a millimeter scale.Methods:For 20 patients with breast cancer treated with proton radiotherapy after breast conserving surgery, PET-CT scan was performed approximately 10 min after the end of proton radiotherapy. The images of PET-CT were processed for ROI determination and sampling line (profile) extraction on a Raystation RV workstation to calculate the actual difference between the predicted and real radioactivity from the same spatial location as obtained by PET acquisition R50. Then, the differences in the spatial location between the actual process of proton irradiation and the planned process were obtained. Depth difference values for each pair of sampling lines were presented. Results:For 20 patients with breast cancer with a median follow-up of 22 months (range 12 - 46 months), all patients survived at the last follow-up, and no radiation pneumonitis was observed during the follow-up period. Among the verification results of 21 cases, the depth difference of evenly distributed was (-0.75±1.89) mm in the primary field and (-0.82±2.06) mm in the secondary field; The depth difference of sequential treatment was (1.81±1.87) mm in the primary field and (1.32±1.74) mm in the secondary field; The depth difference of synchronous addition in the primary field was (-1.47±1.44) mm, and the depth difference in the secondary field was (-1.48±2.11) mm.Conclusion:The results of off-line PET-CT in vivo biological verification show that the accuracy of the dose boundary cut-off was within 3 mm in breast cancer patients, which meets the clinical and physician requirement for the precision in breast cancer treatment.
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@#Adenoid cystic carcinoma of lacrimal gland is the most common malignant epithelial tumor of the lacrimal gland, and surgical treatment alone shows unsatisfactory result. In recent years, as the application of radiotherapy and chemotherapy, changes have happened in the treatment modality for adenoid cystic carcinoma of lacrimal gland. On one hand, clinical staging is gradually refined, which promote the application of standardized comprehensive treatment. On the other hand, neoadjuvant therapies, such as proton radiotherapy, neutron radiotherapy and intra-arterial cytoreductive chemotherapy, can further improve the application of eye-sparing surgery, decrease the rate of local recurrence and metastasis, and prolong the disease-free survival. In this review, we attempt to arrive at some general insights regarding the progress of treatment in adenoid cystic carcinoma of lacrimal gland, in order to provide new reference basis.
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Compared with intensity-modulated photon therapy, intensity-modulated proton therapy has significant dose advantages. However,the dose gradient of proton Bragg peak is relatively high,and the proton therapy is likely to be affected by range uncertainties,setup uncertainties and antonymic changes,etc. The difference between the planning dose and actual dose caused by respiratory motion hinders the widespread use of intensity-modulated proton therapy in thoracic cancers. In this paper,research progress on the effect of respiratory motion on intensity-modulated proton therapy and how to reduce the effect were summarized,aiming to provide reference for clinicians and researchers.
ABSTRACT
Depth of prostate volume from the skin can vary due to intra-fractional and inter-fractional movements, which may result in dose reduction to the target volume. Therefore we evaluated the feasibility of automated depth determination-based adaptive proton therapy to minimize the effect of inter-fractional movements of the prostate. Based on the center of mass method, using three fiducial gold markers in the prostate target volume, we determined the differences between the planning and treatment stages in prostate target location. Thirty-eight images from 10 patients were used to assess the automated depth determination method, which was also compared with manually determined depth values. The mean differences in prostate target location for the left to right (LR) and superior to inferior (SI) directions were 0.9 mm and 2.3 mm, respectively, while the maximum discrepancies in location in individual patients were 3.3 mm and 7.2 mm, respectively. In the bilateral beam configuration, the difference in the LR direction represents the target depth changes from 0.7 mm to 3.3 mm in this study. We found that 42.1%, 26.3% and 2.6% of thirty-eight inspections showed greater than 1 mm, 2 mm and 3 mm depth differences, respectively, between the planning and treatment stages. Adaptive planning based on automated depth determination may be a solution for inter-fractional movements of the prostate in proton therapy since small depth changes of the target can significantly reduce target dose during proton treatment of prostate cancer patients.
Subject(s)
Humans , Prostate , Prostatic Neoplasms , Proton Therapy , Protons , SkinABSTRACT
Depth of prostate volume from the skin can vary due to intra-fractional and inter-fractional movements, which may result in dose reduction to the target volume. Therefore we evaluated the feasibility of automated depth determination-based adaptive proton therapy to minimize the effect of inter-fractional movements of the prostate. Based on the center of mass method, using three fiducial gold markers in the prostate target volume, we determined the differences between the planning and treatment stages in prostate target location. Thirty-eight images from 10 patients were used to assess the automated depth determination method, which was also compared with manually determined depth values. The mean differences in prostate target location for the left to right (LR) and superior to inferior (SI) directions were 0.9 mm and 2.3 mm, respectively, while the maximum discrepancies in location in individual patients were 3.3 mm and 7.2 mm, respectively. In the bilateral beam configuration, the difference in the LR direction represents the target depth changes from 0.7 mm to 3.3 mm in this study. We found that 42.1%, 26.3% and 2.6% of thirty-eight inspections showed greater than 1 mm, 2 mm and 3 mm depth differences, respectively, between the planning and treatment stages. Adaptive planning based on automated depth determination may be a solution for inter-fractional movements of the prostate in proton therapy since small depth changes of the target can significantly reduce target dose during proton treatment of prostate cancer patients.