This paper aims to propose a noninvasive radiotherapy patient positioning system based on structured light surface imaging, and evaluate its clinical feasibility. First, structured light sensors were used to obtain the panoramic point clouds during radiotherapy positioning in real time. The fusion of different point clouds and coordinate transformation were realized based on optical calibration and pose estimation, and the body surface was segmented referring to the preset region of interest (ROI). Then, the global-local registration of cross-source point cloud was achieved based on algorithms such as random sample consensus (RANSAC) and iterative closest point (ICP), to calculate 6 degrees of freedom (DoF) positioning deviation and provide guidance for the correction of couch shifts. The evaluation of the system was carried out based on a rigid adult phantom and volunteers' body, which included positioning error, correlation analysis, and receiver operating characteristic (ROC) analysis. Using Cone Beam CT (CBCT) as the gold standard, the maximum translation and rotation errors of this system were (1.5 ± 0.9) mm along Vrt direction (chest) and (0.7 ± 0.3) ° along Pitch direction (head and neck). The Pearson correlation coefficient between results of system outputs and CBCT verification distributed in an interval of [0.80, 0.84]. Results of ROC analysis showed that the translational and rotational AUC values were 0.82 and 0.85, respectively. In the 4D freedom accuracy test on the human body of volunteers, the maximum translation and rotation errors were (2.6 ± 1.1) mm (Vrt direction, chest and abdomen) and (0.8 ± 0.4)° (Rtn direction, chest and abdomen) respectively. In summary, the positioning system based on structured light body surface imaging proposed in this article can ensure positioning accuracy without surface markers and additional doses, and is feasible for clinical application.
Humans ; Patient Positioning/methods* ; Phantoms, Imaging ; Cone-Beam Computed Tomography ; Algorithms ; Radiotherapy, Image-Guided/methods* ; Radiotherapy Planning, Computer-Assisted/methods*

OBJECTIVE: To evaluate the intra-fraction and inter-fraction positional deviations in head and neck tumor patients undergoing intensity-modulated radiation therapy (IMRT) guided by cone-beam CT (CBCT), as well as the correction capability and stability of the HexaPOD evo RT 6D couch in addressing these deviations. METHODS: From May 2019 to April 2022, 59 consecutive patients with head and neck tumors were enrolled at the Department of Radiation Oncology, Peking University Third Hospital.Using the Elekta AXESSE image-guided stereotactic treatment system, a pre-treatment CBCT scan was performed, followed by bone window mode registration with the planning reference images.Deviations were corrected automatically or manually on the 6D couch, followed by a second CBCT scan for confirmation of the deviation correction.Positional errors in translation (X, Y, Z directions) and rotation (Rx, Ry, Rz directions) were recorded before and after correction, and intra-fraction and inter-fraction positional errors were analyzed. RESULTS: Positional error data before and after correction of the 6D couch were successfully obtained and corrected online in 506 CBCT scans.The maximum positional errors before and after correction were 0.90 cm to 0.04 cm (X direction), 1.74 cm to 0.09 cm (Y direction), 1.80 cm to 0.09 cm (Z direction), and 2.90° to 0.14°(Rx direction), 3.00° to 0.15°(Ry direction), 3.00° to 0.15°(Rz direction), respectively.The mean absolute values of translational (X, Y, Z directions) and rotational (Rx, Ry, Rz directions) errors significantly decreased after online correction, from 0.18 cm, 0.22 cm, 0.25 cm, and 0.82°, 1.11°, 0.73° to 0.01 cm, 0.01 cm, 0.01 cm, and 0.04°, 0.06°, 0.04°(all P values < 0.001).After correction, the frequencies of translational errors less than 0.10 cm in the X, Y, Z directions were 99.60%, 98.62%, and 95.45%, respectively, and the frequencies of rotational errors less than 0.2° were all above 99.80%. CONCLUSION Online correction combined with CBCT and the 6D couch significantly reduces both translational and rotational positional errors in patients undergoing head and neck radiation therapy, greatly enhancing the precision of treatment.
Humans ; Cone-Beam Computed Tomography ; Head and Neck Neoplasms/diagnostic imaging* ; Radiotherapy, Image-Guided/methods* ; Radiotherapy, Intensity-Modulated/methods* ; Patient Positioning/methods* ; Radiotherapy Planning, Computer-Assisted/methods* ; Male ; Radiotherapy Setup Errors/prevention & control* ; Female

This article briefly describes the imaging performance standards of the kilovolt X-ray image guidance system used in radiotherapy, analyzes the main aspects that should be considered in the image quality of X-IGRT system, and focuses on parameters that should be considered in the imaging performance evaluation criteria of the CBCT X-IGRT. The purpose is to sort out the imaging performance evaluation standards of kilovolt X-IGRT system, clarify the image quality requirements of X-IGRT equipment, and reach a consensus when evaluating the imaging performance of X-IGRT system.
Radiotherapy Planning, Computer-Assisted/methods* ; Cone-Beam Computed Tomography/methods* ; Spiral Cone-Beam Computed Tomography ; Radiotherapy, Intensity-Modulated/methods* ; Radiotherapy, Image-Guided/methods*

Biology-guided radiotherapy (BgRT) is a novel technique of external beam radiotherapy, combining positron emission tomography-computed tomography (PET-CT) with a linear accelerator (LINAC). The key innovation is to utilize PET signals from tracers in tumor tissues for real-time tracking and guiding beamlets. Compared with a traditional LINAC system, a BgRT system is more complex in hardware design, software algorithm, system integration and clinical workflow. RefleXion Medical has developed the world's first BgRT system. Nevertheless, its actively advertised function, PET-guided radiotherapy, is still in the research and development phase. In this review study, we presented a number of issues related to BgRT, including its technical advantages and potential challenges.
Positron Emission Tomography Computed Tomography ; Radiotherapy Planning, Computer-Assisted/methods* ; Algorithms ; Particle Accelerators ; Biology ; Radiotherapy, Image-Guided/methods* ; Radiotherapy Dosage

Image-guided radiation therapy using magnetic resonance imaging (MRI) is a new technology that has been widely studied and developed in recent years. The technology combines the advantages of MRI imaging, and can offer online real-time tracking of tumor and adjacent organs at risk, as well as real-time optimization of radiotherapy plan. In order to provide a comprehensive understanding of this technology, and to grasp the international development and trends in this field, this paper reviews and summarizes related researches, so as to make the researchers and clinical personnel in this field to understand recent status of this technology, and carry out corresponding researches. This paper summarizes the advantages of MRI and the research progress of MRI linear accelerator (MR-Linac), online guidance, adaptive optimization, and dosimetry-related research. Possible development direction of these technologies in the future is also discussed. It is expected that this review can provide a certain reference value for clinician and related researchers to understand the research progress in the field.
Magnetic Resonance Imaging ; Particle Accelerators ; Radiometry ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Image-Guided

OBJECTIVE: To investigate the efficacy of image-guided radioactive 125I seed (IGRIS) implantation for pelvic recurrent cervical cancer (PRCC) after external beam radiotherapy (EBRT), and analyze the influence of clinical and dosimetric factors on efficacy. METHODS: From July 2005 to October 2015, 36 patients with PRCC received IGRIS. We evaluated local progression-free survival (LPFS) and overall survival (OS). RESULTS: The median follow up was 11.5 months. The 1- and 2-year LPFS rate was 34.9% and 20%, respectively. The multivariate analysis indicated recurrence site (central or pelvic wall) (hazard ratio [HR]=0.294; 95% confidence interval [CI]=0.121–0.718), lesion volume (HR=2.898; 95% CI=1.139–7.372), D 90 (HR=0.332; 95% CI=0.130–0.850) were the independent factors affecting LPFS. The 1- and 2-year OS rate was 52.0% and 19.6%, respectively. The multivariate analysis suggested pathological type (HR=9.713; 95% CI=2.136–44.176) and recurrence site (HR=0.358; 95% CI=0.136–0.940) were the independent factors affecting OS. The dosimetric parameters of 33 patients mainly included D 90 (128.5±47.4 Gy), D 100 (50.4±23.7 Gy) and V 100 (86.7%±12.9%). When D 90 ≥105 Gy or D 100 ≥55 Gy or V 100 ≥91%, LPFS was extended significantly, but no significant difference for OS. The 79.2% of 24 patients with local pain were suffering from pain downgraded after radioactive 125I seed implantation. CONCLUSION: IGRIS implantation could be a safe and effective salvage treatment for PRCC after EBRT, which could markedly release the pain. Recurrence site, tumor volume and dose were the main factors affected efficacy. Compared with central recurrence, it was more suitable for patients with pelvic wall recurrent cervical cancer after EBRT.
Brachytherapy ; Disease-Free Survival ; Follow-Up Studies ; Humans ; Multivariate Analysis ; Radiometry ; Radiotherapy* ; Radiotherapy, Image-Guided ; Recurrence ; Salvage Therapy* ; Tumor Burden ; Uterine Cervical Neoplasms*

Stereotactic body radiotherapy (SBRT) is an advanced form of radiotherapy (RT) with a growing interest on its application in the treatment of hepatocellular carcinoma (HCC). It can deliver ablative radiation doses to tumors in a few fractions without excessive doses to normal tissues, with the help of advanced modern RT and imaging technologies. Currently, SBRT is recommended as an alternative to curative treatments, such as surgery and radiofrequency ablation. This review discusses the current status of SBRT to aid in the decision making on how it is incorporated into the HCC management.
Carcinoma, Hepatocellular ; Catheter Ablation ; Decision Making ; Radiosurgery ; Radiotherapy ; Radiotherapy, Image-Guided

PURPOSE: The aim of this retrospective study was to investigate the use of a radiopaque tissue fiducial marker (TFM) in the treatment of prostate cancer patients who undergo post-prostatectomy radiotherapy (PPRT). TFM safety, its role and benefit in quantifying the set-up uncertainties in patients undergoing PPRT image-guided radiotherapy were assessed. MATERIALS AND METHODS: A total of 45 consecutive PPRT patients underwent transperineal implantation of TFM at the level of vesicourethral anastomosis in the retrovesical tissue prior to intensity-modulated radiotherapy. Prostate bed motion was calculated by measuring the position of the TFM relative to the pelvic bony anatomy on daily cone-beam computed tomography. The stability and visibility of the TFM were assessed in the initial 10 patients. RESULTS: No postoperative complications were recorded. A total of 3,500 images were analysed. The calculated prostate bed motion for bony landmark matching relative to TFM were 2.25 mm in the left-right, 5.89 mm in the superior-inferior, and 6.59 mm in the anterior-posterior directions. A significant 36% reduction in the mean volume of rectum receiving 70 Gy (rV₇₀) was achieved for a uniform planning target volume (PTV) margin of 7 mm compared with the Australian and New Zealand Faculty of Radiation Oncology Genito-Urinary Group recommended PTV margin of 10 mm. CONCLUSION: The use of TFM was safe and can potentially eliminate set-up errors associated with bony landmark matching, thereby allowing for tighter PTV margins and a consequent favourable reduction in dose delivered to the bladder and rectum, with potential improvements in toxicities.
Clothing ; Cone-Beam Computed Tomography ; Fiducial Markers ; Humans ; New Zealand ; Postoperative Complications ; Prostate ; Prostatectomy ; Prostatic Neoplasms ; Radiation Oncology ; Radiotherapy ; Radiotherapy, Image-Guided ; Radiotherapy, Intensity-Modulated ; Rectum ; Retrospective Studies ; Urinary Bladder

PURPOSE: The aim of this study was to identify volume changes and dose variations of rectum and bladder during radiation therapy in prostate cancer (PC) patients. MATERIALS AND METHODS: We analyzed 20 patients with PC treated with helical tomotherapy. Daily image guidance was performed. We re-contoured the entire bladder and rectum including its contents as well as the organ walls on megavoltage computed tomography once a week. Dose variations were analyzed by means of Dmedian, Dmean, Dmax, V₁₀ to V₇₅, as well as the organs at risk (OAR) volume. Further, we investigated the correlation between volume changes and changes in Dmean of OAR.
Humans ; Organs at Risk ; Prostate ; Prostatic Neoplasms ; Radiotherapy, Image-Guided ; Radiotherapy, Intensity-Modulated ; Rectum ; Urinary Bladder

With increasing clinical use, radiotherapy (RT) has been considered reliable and effective method for hepatocellular carcinoma (HCC) treatment, depending on extent of disease and patient characteristics. RT for HCC can improve therapeutic outcomes through excellent local control, downstaging, conversion from unresectable to resectable status, and treatments of unresectable HCCs with vessel invasion or multiple intrahepatic metastases. In addition, further development of modern RT technologies, including image-guided radiotherapy (IGRT), intensity-modulated radiotherapy (IMRT), and stereotactic body radiotherapy, has expanded the indication of RT. An essential feature of IGRT is that it allows image guidance therapy through in-room images obtained during radiation delivery. Compared with 3D-conformal RT, distinctions of IMRT are inverse treatment planning process and use of a large number of treatment fields or subfields, which provide high precision and exquisitely conformal dose distribution. These modern RT techniques allow more precise treatment by reducing inter- and intra-fractional errors resulting from daily changes and irradiated dose at surrounding normal tissues. More recently, particle therapy has been actively investigated to improve effectiveness of RT. This review discusses modern RT strategies for HCC, as well as optimal selection of RT in multimodal approach for HCC.
Carcinoma, Hepatocellular* ; Humans ; Methods ; Neoplasm Metastasis ; Radiosurgery ; Radiotherapy* ; Radiotherapy, Image-Guided ; Radiotherapy, Intensity-Modulated