• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Cage-like radiotherapy system for noncoplanar radiotherapy

    2021-03-18 13:27:28ChuanMengNiuMingHuiLiJianRongDai
    Nuclear Science and Techniques 2021年2期

    Chuan-Meng Niu? Ming-Hui Li ? Jian-Rong Dai

    Abstract The aim of this study was to design a cage-like radiotherapy system(CRTS)to further promote the clinical application of noncoplanar radiotherapy. The CRTS comprises two stands, two O-rings, several arc girders, an X-ray head, an imaging subsystem, and a treatment couch.The X-ray head rotates with O-rings around the patient’s body and slides along the arc girder. Compared with the C-arm linear accelerator(C-Linac),the clinically available spatial irradiation angle ranges (SIARs) of the CRTS for the head,chest,and abdomen were 33%,63.6%,and 62.6%larger, respectively. Moreover, according to a preliminary planning comparison based on the dose distribution simulation method, the CRTS achieved much better protection of normal tissue than the C-Linac. Furthermore,the CRTS enabled accurate noncoplanar irradiation without movement of the body being irradiated, allowed automatic control of the movements of different parts without risk of collisions,and provided continuous radiation over an angle that considerably exceeded a full turn. These advantages make CRTS very promising for noncoplanar radiotherapy.

    Keywords Radiotherapy system · Noncoplanar radiotherapy · Spatial irradiation angle range · Spherical surface area

    1 Introduction

    In principle,noncoplanar beam geometry is a superset of the coplanar beam solution space. It has been shown to yield superior dosimetry when it is appropriately implemented[1–4].Some noncoplanar static beams or arcs have demonstrated substantial dosimetric advantages over current static intensity-modulated radiation therapy and volumetric-modulated arc therapy, which employ only coplanar beams or arcs. These advantages of noncoplanar static beams or arcs include improved dose conformality,normal-organ sparing,and dose escalation for treatments to the brain [5, 6], head and neck [7, 8], liver [1], lung [9],breast [10], and prostate [11–13]. However, clinical use of noncoplanar beams or arcs in external radiation therapy has been limited,with the exception of specialized stereotactic radiosurgery machines, such as the Gamma Knife, Cyber Knife, and conventional linear-accelerator-based stereotactic radiosurgery using cone collimators and multiple intersecting arcs.Adoption of noncoplanar radiotherapy on the most widely available C-arm gantry systems has been hindered by technical challenges, including the lack of practical integrated beam orientation and fluence optimization tools, as well as collision hazards and long treatment times. Nevertheless, steady progress has been made in noncoplanar treatment planning and delivery research in recent years. Several researchers have examined automated techniques for determining the optimal configuration of noncoplanar beams [14]. A robust commercial solution that optimizes the beam angle selection for noncoplanar intensity-modulated radiation therapy or volumetric modulated arc therapy will likely be developed in the near future. Collisions can be prevented with pretreatment 3D modeling and the use of proximity sensors[15–18].Many newer C-arm linear accelerators(C-Linacs)equipped with a robotic couch and gantry are technically capable of automation, which enables effective plan delivery [11].

    These recent developments have revitalized interest in noncoplanar planning. However, the C-Linac has the challenging issue of machine geometric limitations, which exclude many noncoplanar angles. Thus, the restricted noncoplanar angle selection range may inhibit achievement of optimal planning dosimetry.Moreover,when delivering noncoplanar beams and moving the treatment couch and gantry,great caution must be exercised to prevent potential setup errors. This is especially the case during treatment with a large number of noncoplanar beams [19, 20]. To overcome these problems and promote the clinical adoption of noncoplanar beams for external radiotherapy, we developed an innovative cage-like radiotherapy system(CRTS),for which a Chinese invention patent (application number:2018100784318)is pending.This article describes the CRTS construction and the results of a preliminary comparative analysis with a C-Linac.

    2 Materials and methods

    2.1 Introduction of the CRTS

    The overall structure of the CRTS is presented in Fig. 1.Two stands are fixed to the ground in parallel, and their circular through-holes are located coaxially along the longitudinal axis. A free treatment volume is formed between the two stands. To prevent collisions, no moving elements are allowed to be present within this volume during the treatment process. A support board with three orthogonal translations is installed on the two stands by its two ends. The couch top can translate from the treatment couch to the support board and carry the patient to the irradiation position.One O-ring is embedded in each of the circular through-holes of the two stands. The gantry is mainly composed of several arc girders that stretch across the O-rings and rotate around the longitudinal axis that passes through the isocenter(ISO).The X-ray head,which includes an X-band accelerator and a multi-leaf collimator(MLC), is mounted on one of the arc girders and is moveable. The source-axis distance (SAD) remains fixed for the range of translation distances of the X-ray head along the arc girder. The X-ray head can be translated in two degrees of freedom: rotating around the treatment volume,and sliding on the arc girder along the longitudinal axis, thereby irradiating the body from different directions around the treatment volume.

    The CRTS adopts a double-stand structure and has considerable overall support strength. Thus, multiple sets of slide rails or arc girders of the gantry can be installed between the two fixed stands to carry the imaging devices,counterweights, and other ancillary equipment, which facilitate the image-guided noncoplanar radiotherapy(Fig. 1). An electronic portal imaging device (EPID) and beam stopper are fixed together. They can translate synchronously with the X-ray head along the opposite arc girder. The beam stopper has two functions: blocking unwanted X-rays and providing a counterbalance.

    To apply radiotherapy using the CRTS, the patient is first transported to the treatment position by the treatment couch top. Next, an imaging subsystem is used to identify any setup errors due to the support board motion.Then,the X-ray head is driven by the treatment plan to deliver the prescribed dose to the target area. It is not necessary to move the patient during the whole noncoplanar radiotherapy treatment process.

    2.2 Design of overall structure

    The basis of the overall structural design was to prevent a collision,which is the closest distance between the X-ray head and the treatment volume. This distance cannot be less than the safety buffer distance, s, as shown in Fig. 2.This qualification can be expressed as the following inequality:

    where α indicates the maximum angle that the X-ray head can translate along the arc girder, and d denotes the diameter of the lower end of the X-ray head.The SAD can be calculated based on the schematic diagram shown in Fig. 2 using

    where H indicates the distance between the lower surface of the X-ray head and the treatment volume surface when the X-ray head is at the neutral position, D denotes the diameter of the treatment volume, and h is the distance between the target and the lower surface of the X-ray head.

    2.3 Design of the X-ray head

    The X-ray head primarily consists of an X-band accelerator and an MLC,as shown in Fig. 3.No flattening filter is used, and a couple of Y jaws with the orthogonally arranged MLC work together to modulate the beam shape.The microwave subsystem is installed perpendicularly to the accelerator. A suitable SAD and a light weight can be obtained owing to the compact structure design of the X-ray head.

    2.4 Computing method to calculate the spatial irradiation angle ranges (SIARs)

    The X-ray source can ideally reach any positioning point on a virtual spherical surface that is centered at the ISO and has a radius equal to the SAD to be irradiated, which is known as 4π radiotherapy. However,the limitations of the mechanical structure mean that ideal 4π radiotherapy cannot be realized. The SIAR that is actually realized by the X-ray source is calculated using the following formula:

    Fig.2 The schematic diagram used to introduce the overall structure design basis

    where φ represents the SIAR numerical value, Srdenotes the area of the partial spherical surface formed by the position points that the X-ray source can achieve,and Ssis the area of the entire virtual spherical surface, which is given by

    2.5 SIAR of the CRTS

    With the mechanical structure detailed in Sect. 2.1, the reachable spatial location points of the X-ray head of the CRTS form a drum-like spherical surface (similar to the whole spherical surface with two poles removed), which will not be changed, even for targets in different parts of the patient’s body(Fig. 4).The drum-like spherical surface area (cSr) is readily obtained using SolidWorks evaluation tools(Premium 2014,Dassault Systems,France).ThecSris entered into Eq. (3) to determine the SIAR of the CRTS.

    2.6 SIAR of the C-Linac

    The SIAR of the C-Linac is not a constant value; it varies widely depending on the patient body shape, tumor location,setup immobilization devices,and machine model[15]. To facilitate a comparison with the CRTS, we adopted an experimental method to measure the SIAR of the C-Linac. The measurements were performed on a Varian Edge Exact Couch combined with a Millennium MLC (Varian Medical Systems, TrueBeam Platform 2.5).The patient’s presence was simulated by placing a cardiopulmonary resuscitation manikin (model GD/CPR10280; size 170 × 50 × 26 cm3; Shanghai Chenbo Science and Education equipment factory)on the top of the couch. The SIARs of the C-Linac for treatments to the head, thorax,and abdomen were measured separately. The target locations of all three sites were assumed to be at the body center for which the widest SIAR could be accepted[17]. The target locations employed for the measurements are presented in Table 1. To determine the maximum gantry angle achievable for each couch position,the couch was rotated at 5°intervals,and the gantry was moved until the closest distance from the gantry to the couch or the manikin was 5 cm (Fig. 5). The couch angle was changed from 0° to 90° and from 270° to 360°.

    Fig.3 (Color online)The X-ray head is mainly composed of an X-band accelerator (left) and a multileaf collimator (right)

    Fig.4 (Color online)The spatial irradiation angle range of the cagelike radiotherapy system expressed as graphical images

    Table 1 Target locations in the head, thorax, and abdomen

    Fig. 5 (Color online) Measurements of the spatial irradiation angle ranges of the C-arm linear accelerator(Edge)for treatment applied to the patient’s head

    2.7 Simulation method of the dose distributions

    To simulate the CRTS dose distributions, a common CLinac model was employed in the treatment planning system as a substitute for the CRTS. It was assumed to have the same SIAR. The beam angle of the CRTS could be determined by θ1and θ2,where the longitudinal angle θ1is the rotation angle of the arc girder around the O-ring,and θ2is the rotation angle of the X-ray head along the arc girder (Fig. 6). The spatial geometric relationship yields

    Fig.6 The coordinate system X-Y-Z was built at the ISO.The X-axis is positive to the right, and the Y-axis is positive toward the upward position. The Z-axis is positive toward the anterior stand and is situated coaxially along the longitudinal axis

    To verify the effectiveness of the simulation method of the CRTS dose distribution, Pinnacle version 9.10(Koninklijke Philips N.V.,Netherlands)was used to design the treatment plans for a breast patient case and a head patient case based on a beam angle selection map for the CRTS (Fig. 7) obtained by inequality (8). For the breast patient case, the prescribed dose was 48 Gy/6 fractions for the planning treatment volume (PTV). The dose limits for the organs at risk(OARs)are listed in Table 2.For the head patient case, the prescribed dose was 52.5 Gy/15 fractions for the planning treatment volume (PTV). The dose limits for the OARs are listed in Table 3.

    Fig.7 The beam angle selection map for the CRTS.The zones filled with the oblique lines are the unreachable beam angle selection areas

    Table 2 Normal tissue dose constraints for the breast patient

    Table 3 Normal tissue dose constraints for the head patient

    For the breast plan based on the CRTS, two spatial arcs in the tangent plane of the breast along the longitudinal direction were selected to irradiate the target area, which we term the ‘spatial volume modulated arc therapy(SVMAT)’. The first arc had a θ1of 34° and θ2ranged from - 45°to + 45°.The second arc had a θ1of 214°and θ2ranged from - 45° to + 45°. However, in the current version of Pinnacle, the available SVMAT trajectories were limited. Thus, we simulated SVMAT plans based on static multi-fields. Two sets of 19 control points were created by dividing θ2by a control spacing of 5°. Optimization was performed using 38 control points as 38 multi-field intensity-modulated radiotherapy(IMRT)plans.The internal adaptive convolution method and direct machine parameter optimization (DMPO) method of the planning system were selected for the dose calculation and optimization, respectively. The corresponding couch angle and gantry angle to each IMRT beam were calculated using Eqs. (5) and (6). We assumed that the simulated dose distribution was comparable with that of SVMAT. To make a preliminary comparison with the C-Linac, the common coplanar VMAT plan was designed using the same constraints as those of the SVMAT plan.Two partial coplanar arcs with gantry angles ranging from 35° to 220°were employed,and the control point spacing was set to 4°.The internal adaptive convolution method and SmartArc method were selected for the dose calculation and optimization, respectively. For the head SVMAT, five spatial arcs along the longitudinal direction were selected to irradiate the target area. For each arc, θ1was 90°, 120°,150°, 180° and 210°, respectively, and θ2ranged from -45° to + 45°. The head SVMAT plan was also simulated based on static multi-fields. The dose calculation method and optimization algorithm were selected to be the same as in the breast case.The noncoplanar VMAT(NVMAT)plan based on the C-Linac for the head case was also designed using the same constraints as the head SVMAT plan. Four partial arcs were employed, and the control point spacing was set to 4°.For the first arc,the couch angle was 0°with a gantry angle ranging from 210° to 310°. For the second arc, the couch angle was 35° with a gantry angle ranging from 310° to 220°. For the third arc, the couch angle was 80°with a gantry angle ranging from 220°to 310°.For the fourth arc, the couch angle was 303° with a gantry angle ranging from 40° to 140°. The internal adaptive convolution method and SmartArc method were selected for the dose calculation and optimization, respectively.

    3 Results

    3.1 Major dimensions

    For the distribution angle of the gamma knife radiation source in the latitudinal direction[21],α was proposed to be 45°.Considering the patient body shape,the preferred center bore diameter was set at 800 mm.The safety buffer distance,s,was set to 5 cm.The diameter of the lower end of the X-ray head,d,was designed to be 600 mm.According to inequality(1),the distance between the lower surface of the X-ray head at the neutral position and the treatment surface H should not be less than 536.4 mm. Owing to the compact structure design, the X-ray head was approximately 400 kg with a total height of 400 mm.The distance from the target to the lower surface of the X-ray head was designed to be 340 mm.By substituting the above parameters into Eq. (2),the SAD of the CRTS was approximately 1280 mm.The radius of the arc girder was designed to be 1300 mm,and the CRTS was approximately 4600 mm in length in the longitudinal direction(without a couch:2600 mm),3170 mm in height,and 2800 mm wide along the latitudinal direction.

    3.2 Comparison of SIAR

    ThecSrof the CRTS could be directly measured by Solidworks evaluation tools. The whole spherical area (Ss)could be calculated by Eq. (4) with a given SAD. By substituting the values ofcSrand Ssinto Eq. (3), the SIAR of the CRTS was 2.83π. The reachable spatial location points of the X-ray head of the C-Linac formed different partial spherical surfaces for targets located in different body regions (Fig. 8). The surface areas of the head, thorax, and abdomen were measured using SolidWorks evaluation tools, and the SIARs of the C-Linac calculated by Eq. (3) were 2.72π, 1.73π, and 1.74π, respectively.Angling the beam toward the overhead area would greatly increase the low-dose region and is thus rarely employed in clinical applications.

    Fig. 8 (Color online) Spatial irradiation angle ranges of the C-arm linear accelerator expressed in graphic images

    After removing the bipolar region of the same size as that of the CRTS,the SIAR of the C-Linac for the patient’s head was 2.13π (Table 4). The clinically available SIARs of the CRTS were 33%, 63.6%, and 62.6% larger than those of the C-Linac for the head and neck, chest, and abdomen, respectively. As reported in the literature[22–24], other radiotherapy systems, such as CyberKnife,Vero, and ZAP, also have smaller SIARs than the CRTS(Table 4). With respect to CyberKnife, its workspace is comprised of pre-assigned nodes that are roughly distributed on a half-sphere surface [22].Considering that the C-Linac head can reach slightly lower than the couch level on the side, the maximum SIAR of CyberKnife is slightly larger than 2π and varies in accordance with the target location and the patient anatomy being treated.Meanwhile,Vero employs an O-ring instead of a C-arm to carry the Linac to rotate around the treatment couch.The O-ring can be skewed around its vertical axis. This skew provides a noncoplanar beam angle selection. The skew angle is limited to approximately ± 60°by mechanical interference between the couch and the O-ring [23]. The maximum SIAR of Vero is calculated to be approximately 2.67π using Eq. (3). However, Vero cannot eliminate the risk of collision owing to its overall structure being similar to that of the C-Linac. Moreover, its SIAR varies significantly in accordance with different target locations, especially for off-center targets.In terms of the Zap system,it is designed specifically for stereotactic radiosurgical (SRS)ablation of intracranial and head and neck lesions. It is mounted on a shielded treatment sphere with dual axes of independent rotation.Thus,the SIAR of ZAP is approximately 2π[24].

    Table 4 SIARs of CRTS and C-Linac

    3.3 Dose distribution

    Figure 9 shows the dose distributions of the breast SVMAT and VMAT for the breast patient. Table 5 summarizes the average dose volume indices for the targets and OARs.The two plans did not differ significantly in terms of any PTV evaluation (PTV_EVAL) parameters. However,the SVMAT plan for the CRTS significantly reduced the doses to the OARS. It is observed that the Dmeanvalue of the contralateral breast is 95.9% lower for the SVMAT plan than for the VMAT plan. The Dmean, V20%, and V5%values of the ipsilateral breast are, respectively, 57.6%,25.9%,and 74.5% lower for the SVMAT plan than for the VMAT plan. The Dmeanvalue of the heart is 93.6% lower for the SVMAT plan than for the VMAT plan. The Dmaxvalue of the planning OAR volume of the cord(PRV_Cord) is 90% lower for the SVMAT plan than for the VMAT plan.

    Figure 10 presents the dose distributions of the SVMAT and NVMAT for the head patient.Table 6 summarizes the average dose volume indices for the targets and OARs.The SVMAT plan obtained better dose indexes of PTV than the NVMAT plan. The heterogeneity index (HI) of theSVMAT plan is 38.5%lower than that of the VMAT plan.Moreover,the SVMAT plan shows better OAR protection.The Dmaxvalues of the spinal cord, brain stem, and hippocampus are, respectively, 58.2%, 13.1%, and 15.3%lower for the SVMAT plan than for the NVMAT plan.

    Table 5 Comparison of dosimetric parameters among SVMAT and VMAT for the breast patient

    Fig. 9 (Color online) Beam arrangements and dose distributions for the breast patient: a SVMAT b VMAT

    Fig. 10 (Color online) Beam arrangements and dose distributions for the head patient: a SVMAT b NVMAT

    Table 6 Comparison of dosimetric parameters of SVMAT and NVMAT for the head patient

    4 Discussion

    Compared with the C-Linac, the CRTS has several advantages for use in noncoplanar radiotherapy. First, the CRTS has a larger SIAR and a more uniform angle selection range than the C-Linac. Thus, the CRTS can be used to irradiate the patient from the anterior and posterior directions, as well as from the left and right directions,using the same beam angle selection range on a drum-like spherical surface (Fig. 4). In contrast, the available irradiation area using the C-Linac is very small when irradiating from the left, right, and posterior directions, but not from the anterior direction (Fig. 8). On account of this advantage, better OAR protection could be achieved for the breast and head patients using the CRTS than the C-Linac(Tables 5 and 6).Second, the CRTS enabled a more direct switch between two noncoplanar beams or arcs than the C-Linac. The CRTS X-ray head was directly translated from one noncoplanar radiotherapy position to another without moving the couch (Fig. 9a). In contrast, the C-Linac gantry could not be directly translated from the anterior noncoplanar angle to the posterior noncoplanar angle owing to the collision between the gantry and the couch (Fig. 11).

    Fig. 11 (Color online) Irradiation position switch between two noncoplanar beams for the C-arm linear accelerator

    Using the C-Linac, the couch first had to be rotated to the non-collision area. Then, it was necessary to rotate the gantry to the posterior irradiation position. Finally, the couch had to be rotated to the noncoplanar position. These complex operations greatly increased the treatment time and collision risk for the C-Linac.Third,the CRTS enabled more convenient treatment planning than the C-Linac.The noncoplanar plan for the CRTS was directly designed without considering collision prevention.In contrast,it was difficult for the C-Linac to detect potential collisions during the treatment planning stage. A common method of collision prevention involves the use of a pretreatment simulation on a Linac. However, the discovery of a potential collision requires the treatment plan to be changed, which increases the noncoplanar planning time and difficulty [15]. Fourth, the CRTS provided much better assurance of patient positioning accuracy than the C-Linac.Fast treatment inherently enhances quality, as it becomes increasingly difficult for the patient to maintain the same position on the couch as the time required for treatment increases [16]. The CRTS enables noncoplanar treatment without the need for therapists to enter the treatment room.All treatment modalities can be performed quickly and are fully automated.Thus,the CRTS will markedly reduce the treatment time of noncoplanar radiotherapy and achieve a greater degree of treatment accuracy compared with the C-Linac.

    In this article, the conceptual engineering design of the CRTS was described.However,our research remains in the preliminary stage; considerably more research should be conducted in future work. First, the mechanical design needs to be improved, including the detailed design of a compact X-ray head equipped with an MLC, design of the O-ring and slide girder structure,and design of an imaging subsystem. Second, the dosimetric benefits from the increased SIAR of the CRTS compared to other radiotherapy systems must be further studied.Based on the dose calculation methods and optimization algorithms to be developed for the SVMAT,many more patient cases could be enrolled for systematic research to demonstrate the dosimetric gains from employing a larger SIAR.Third,the shielding issues require further study. As the CRTS irradiates broader areas of the opposite wall and the ceiling of the therapy room than the C-Linac, additional costs would be incurred to augment the shielding, which is not necessary with conventional equipment. Fourth, the path algorithm for the CRTS should be further studied [25–27]. For noncoplanar treatment with multiple irradiation angles,the path algorithm should provide the optimal trajectory of the X-ray head to reach each irradiation position with the minimum distance. Accordingly, the maximum treatment efficiency can be realized.

    5 Conclusion

    In this article, we proposed the architecture of a novel CRTS that can realize noncoplanar radiotherapy by simply moving the X-ray head in two degrees of freedom without moving the treatment couch. The innovative mechanical design enables the CRTS to achieve a much larger SIAR than the C-Linac and produces no collision hazards. The present preliminary study of CRTS is expected to promote the clinical application of noncoplanar radiotherapy.

    AcknowledgmentsThe authors would like to thank Dong-Sheng Han, Wen Li, Yi-Xin Song, Yuan Tian, and Ke Zhang for their helpful discussions and assistance.

    Author contributionsAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Chuan-Meng Niu, Ming-Hui Li and Jian-Rong Dai.The first draft of the manuscript was written by Chuan-Meng Niu and all authors commented on previous versions of the manuscript.All authors read and approved the final manuscript.

    国产精品永久免费网站| 麻豆av在线久日| 天堂中文最新版在线下载| 99精国产麻豆久久婷婷| 在线观看免费视频网站a站| 久久久久久亚洲精品国产蜜桃av| 波多野结衣av一区二区av| 丁香欧美五月| 波多野结衣av一区二区av| 国产精品久久久av美女十八| 桃红色精品国产亚洲av| 一个人观看的视频www高清免费观看 | 伦理电影免费视频| 欧美丝袜亚洲另类 | 精品久久久精品久久久| 看片在线看免费视频| 精品第一国产精品| 中文字幕高清在线视频| av电影中文网址| 午夜91福利影院| 欧美精品啪啪一区二区三区| 99久久综合精品五月天人人| 国产欧美日韩精品亚洲av| 午夜精品国产一区二区电影| 最新美女视频免费是黄的| 国产午夜精品久久久久久| 欧美黑人精品巨大| 村上凉子中文字幕在线| 黄色 视频免费看| 一进一出抽搐gif免费好疼 | 色精品久久人妻99蜜桃| 大香蕉久久成人网| 操出白浆在线播放| 日韩欧美在线二视频| 在线观看免费高清a一片| 亚洲欧美一区二区三区久久| 色精品久久人妻99蜜桃| 每晚都被弄得嗷嗷叫到高潮| 搡老岳熟女国产| 欧美激情 高清一区二区三区| 天天添夜夜摸| 18禁裸乳无遮挡免费网站照片 | 久久久久久亚洲精品国产蜜桃av| 50天的宝宝边吃奶边哭怎么回事| www日本在线高清视频| 国产99白浆流出| 人人妻,人人澡人人爽秒播| 精品国产一区二区三区四区第35| 国产又色又爽无遮挡免费看| 欧美老熟妇乱子伦牲交| 免费观看人在逋| 亚洲一卡2卡3卡4卡5卡精品中文| 成人三级做爰电影| 久久 成人 亚洲| 欧美精品亚洲一区二区| av天堂在线播放| 一a级毛片在线观看| 俄罗斯特黄特色一大片| tocl精华| 久久久国产一区二区| 免费观看精品视频网站| 一边摸一边抽搐一进一出视频| 亚洲三区欧美一区| 国产深夜福利视频在线观看| 亚洲三区欧美一区| 三上悠亚av全集在线观看| 在线观看一区二区三区激情| 日韩欧美三级三区| 欧美日韩乱码在线| 免费观看人在逋| 亚洲七黄色美女视频| 亚洲一区二区三区欧美精品| 亚洲人成电影观看| 在线观看免费午夜福利视频| 亚洲欧美精品综合久久99| 老司机福利观看| 丰满迷人的少妇在线观看| 久久久久久久久中文| 9热在线视频观看99| 女人被躁到高潮嗷嗷叫费观| 婷婷六月久久综合丁香| 久久精品国产亚洲av香蕉五月| 精品人妻1区二区| 91麻豆精品激情在线观看国产 | 高清av免费在线| netflix在线观看网站| 亚洲中文字幕日韩| 亚洲第一av免费看| 亚洲人成77777在线视频| 欧美日韩乱码在线| netflix在线观看网站| 国产成人欧美| 在线观看一区二区三区激情| 久久国产精品男人的天堂亚洲| 大陆偷拍与自拍| 成人黄色视频免费在线看| 丰满人妻熟妇乱又伦精品不卡| 久久青草综合色| 中文字幕av电影在线播放| 久久伊人香网站| 在线播放国产精品三级| 50天的宝宝边吃奶边哭怎么回事| 男男h啪啪无遮挡| 国产精品久久久久成人av| 九色亚洲精品在线播放| 久久人人精品亚洲av| 亚洲第一青青草原| 亚洲精品粉嫩美女一区| 老司机靠b影院| 亚洲情色 制服丝袜| netflix在线观看网站| 97碰自拍视频| 国产亚洲精品第一综合不卡| 亚洲第一青青草原| 又大又爽又粗| 久久影院123| 久久久久国产精品人妻aⅴ院| 精品人妻1区二区| 亚洲久久久国产精品| 久久久久国内视频| svipshipincom国产片| 无限看片的www在线观看| 999久久久国产精品视频| 亚洲av成人一区二区三| 黄片播放在线免费| 在线十欧美十亚洲十日本专区| 欧美+亚洲+日韩+国产| 免费在线观看完整版高清| 水蜜桃什么品种好| 中文欧美无线码| 国产有黄有色有爽视频| 制服诱惑二区| 91国产中文字幕| 亚洲五月天丁香| 中文字幕人妻熟女乱码| www国产在线视频色| 男女高潮啪啪啪动态图| 国产精品永久免费网站| 色综合婷婷激情| 国产99久久九九免费精品| 国产免费男女视频| 精品国产国语对白av| 亚洲专区字幕在线| 久久久久久免费高清国产稀缺| 午夜视频精品福利| 99久久人妻综合| avwww免费| 亚洲视频免费观看视频| 精品久久久久久久毛片微露脸| 如日韩欧美国产精品一区二区三区| 91国产中文字幕| e午夜精品久久久久久久| 女人精品久久久久毛片| 老司机福利观看| 欧美国产精品va在线观看不卡| 国产深夜福利视频在线观看| 亚洲,欧美精品.| 丰满的人妻完整版| 亚洲成人精品中文字幕电影 | 99riav亚洲国产免费| 成人手机av| 在线观看免费午夜福利视频| 国产精品一区二区在线不卡| 水蜜桃什么品种好| 久久精品aⅴ一区二区三区四区| av网站免费在线观看视频| 首页视频小说图片口味搜索| 免费在线观看视频国产中文字幕亚洲| 亚洲国产精品sss在线观看 | 精品国产乱子伦一区二区三区| 侵犯人妻中文字幕一二三四区| 久久亚洲精品不卡| 满18在线观看网站| bbb黄色大片| xxxhd国产人妻xxx| 国产一区二区三区视频了| 99精品欧美一区二区三区四区| 中国美女看黄片| 欧美另类亚洲清纯唯美| 亚洲专区字幕在线| 亚洲美女黄片视频| 琪琪午夜伦伦电影理论片6080| 午夜精品久久久久久毛片777| 在线av久久热| 夜夜躁狠狠躁天天躁| 手机成人av网站| 日本 av在线| 电影成人av| 搡老乐熟女国产| 欧美日韩黄片免| 国产av一区二区精品久久| 久久久久九九精品影院| 国产成人av激情在线播放| 国产精品综合久久久久久久免费 | 亚洲成人国产一区在线观看| 免费看十八禁软件| 国产激情欧美一区二区| av天堂在线播放| 18禁美女被吸乳视频| 丰满人妻熟妇乱又伦精品不卡| 一区二区三区激情视频| 亚洲成人精品中文字幕电影 | 亚洲精品国产色婷婷电影| 欧美日韩瑟瑟在线播放| 亚洲精品久久成人aⅴ小说| 久久精品成人免费网站| 人人澡人人妻人| 久久精品91蜜桃| 丰满的人妻完整版| 18禁美女被吸乳视频| 精品日产1卡2卡| 中文字幕高清在线视频| 黄网站色视频无遮挡免费观看| 国产av一区二区精品久久| 中文字幕另类日韩欧美亚洲嫩草| 制服诱惑二区| 丰满人妻熟妇乱又伦精品不卡| 精品国产国语对白av| 麻豆久久精品国产亚洲av | 女人被狂操c到高潮| 级片在线观看| 一本综合久久免费| 成人国产一区最新在线观看| 国产亚洲欧美在线一区二区| bbb黄色大片| 男男h啪啪无遮挡| 精品国产超薄肉色丝袜足j| 国产精品免费一区二区三区在线| 久久久久久久久久久久大奶| 日本黄色日本黄色录像| 无遮挡黄片免费观看| 亚洲av熟女| 欧美黄色淫秽网站| 亚洲一区二区三区不卡视频| 乱人伦中国视频| 美女高潮到喷水免费观看| 在线观看日韩欧美| 亚洲欧洲精品一区二区精品久久久| 一二三四在线观看免费中文在| 国产不卡一卡二| 男女下面插进去视频免费观看| 亚洲avbb在线观看| 国产乱人伦免费视频| 男人舔女人下体高潮全视频| 亚洲国产欧美一区二区综合| svipshipincom国产片| 变态另类成人亚洲欧美熟女 | 脱女人内裤的视频| 国产精品综合久久久久久久免费 | 黄色 视频免费看| 免费在线观看视频国产中文字幕亚洲| 国产精品亚洲一级av第二区| 中文字幕人妻丝袜一区二区| 色精品久久人妻99蜜桃| 亚洲人成电影观看| 精品国产乱子伦一区二区三区| 亚洲三区欧美一区| 久久精品亚洲熟妇少妇任你| 无人区码免费观看不卡| 欧美日韩精品网址| a级片在线免费高清观看视频| 丝袜人妻中文字幕| 可以免费在线观看a视频的电影网站| 欧美性长视频在线观看| 在线免费观看的www视频| 免费在线观看黄色视频的| 美国免费a级毛片| 国产成人系列免费观看| 日韩三级视频一区二区三区| 久久午夜亚洲精品久久| 国产成人免费无遮挡视频| 老司机深夜福利视频在线观看| 1024香蕉在线观看| 女警被强在线播放| 精品一区二区三区av网在线观看| 亚洲美女黄片视频| 高清黄色对白视频在线免费看| 欧美丝袜亚洲另类 | 国产成人精品久久二区二区91| cao死你这个sao货| 成人影院久久| 老司机靠b影院| 美女高潮到喷水免费观看| 成人国语在线视频| 成年版毛片免费区| 天堂俺去俺来也www色官网| 国产xxxxx性猛交| a在线观看视频网站| 成人永久免费在线观看视频| 亚洲片人在线观看| 亚洲精品国产一区二区精华液| 国产精品1区2区在线观看.| 亚洲熟妇中文字幕五十中出 | 88av欧美| 久久影院123| 男女下面进入的视频免费午夜 | 日韩视频一区二区在线观看| xxx96com| 在线免费观看的www视频| 亚洲精品国产一区二区精华液| 涩涩av久久男人的天堂| 国产精品秋霞免费鲁丝片| 欧美精品亚洲一区二区| 成人免费观看视频高清| 精品久久久久久电影网| 男人的好看免费观看在线视频 | 真人一进一出gif抽搐免费| 精品久久久久久成人av| 亚洲欧美精品综合一区二区三区| 一区二区日韩欧美中文字幕| 99riav亚洲国产免费| 亚洲色图综合在线观看| 一区二区三区激情视频| 国产一区二区激情短视频| e午夜精品久久久久久久| 久久国产亚洲av麻豆专区| 手机成人av网站| 国产精品二区激情视频| 三级毛片av免费| 久久精品国产综合久久久| 1024香蕉在线观看| 国产av又大| 好看av亚洲va欧美ⅴa在| 美女高潮喷水抽搐中文字幕| 人人澡人人妻人| 久久精品国产清高在天天线| 国产精品一区二区在线不卡| 亚洲,欧美精品.| svipshipincom国产片| 久久国产精品男人的天堂亚洲| 女人精品久久久久毛片| 天天躁狠狠躁夜夜躁狠狠躁| 国产成人欧美在线观看| 日韩成人在线观看一区二区三区| 久久精品国产99精品国产亚洲性色 | 正在播放国产对白刺激| 精品一品国产午夜福利视频| 欧美中文综合在线视频| 精品国产一区二区三区四区第35| 亚洲avbb在线观看| 亚洲精品久久成人aⅴ小说| 欧美成人免费av一区二区三区| 波多野结衣av一区二区av| 老司机午夜十八禁免费视频| av天堂在线播放| 国产麻豆69| 一进一出抽搐gif免费好疼 | 一a级毛片在线观看| 可以免费在线观看a视频的电影网站| 新久久久久国产一级毛片| 国产精品美女特级片免费视频播放器 | 亚洲国产精品合色在线| 女生性感内裤真人,穿戴方法视频| 欧美日韩亚洲综合一区二区三区_| 成人18禁在线播放| 老熟妇仑乱视频hdxx| 国产91精品成人一区二区三区| 亚洲av第一区精品v没综合| 黑人猛操日本美女一级片| 精品高清国产在线一区| 日本黄色视频三级网站网址| 亚洲av电影在线进入| 免费不卡黄色视频| 欧美精品亚洲一区二区| 国产又爽黄色视频| 欧美日韩乱码在线| 免费观看精品视频网站| 80岁老熟妇乱子伦牲交| 成人手机av| 女人爽到高潮嗷嗷叫在线视频| 精品国产一区二区三区四区第35| 视频在线观看一区二区三区| 国产成人av激情在线播放| 最好的美女福利视频网| 日本免费a在线| 日韩有码中文字幕| 午夜激情av网站| 美女高潮到喷水免费观看| 大码成人一级视频| 久久久久久人人人人人| av网站免费在线观看视频| 亚洲欧美一区二区三区久久| 久久亚洲精品不卡| 欧美黄色淫秽网站| 国产不卡一卡二| 午夜久久久在线观看| 国产高清激情床上av| 国产激情久久老熟女| 午夜a级毛片| 欧美另类亚洲清纯唯美| 欧美午夜高清在线| 国产精品一区二区免费欧美| 19禁男女啪啪无遮挡网站| 久久国产亚洲av麻豆专区| 午夜福利免费观看在线| 日韩免费高清中文字幕av| 成人亚洲精品一区在线观看| 国产精品一区二区免费欧美| 国产高清激情床上av| 国产成人av教育| 欧美大码av| 国产精品98久久久久久宅男小说| 在线观看一区二区三区| 后天国语完整版免费观看| 欧美日韩国产mv在线观看视频| 丁香欧美五月| 大香蕉久久成人网| 女性被躁到高潮视频| 嫩草影院精品99| 免费在线观看日本一区| 欧美黑人精品巨大| 久久久国产成人精品二区 | 电影成人av| 一本大道久久a久久精品| 性色av乱码一区二区三区2| 久久久久国产精品人妻aⅴ院| 亚洲一码二码三码区别大吗| 变态另类成人亚洲欧美熟女 | 黑人欧美特级aaaaaa片| 亚洲精品粉嫩美女一区| 国产亚洲精品综合一区在线观看 | 黑人巨大精品欧美一区二区mp4| a在线观看视频网站| 不卡一级毛片| 老司机午夜十八禁免费视频| 精品国产一区二区三区四区第35| 中文字幕最新亚洲高清| 一二三四社区在线视频社区8| 免费一级毛片在线播放高清视频 | 成人黄色视频免费在线看| 亚洲欧美激情在线| 亚洲国产欧美一区二区综合| 人人澡人人妻人| 国产深夜福利视频在线观看| 精品国产乱码久久久久久男人| 亚洲成人精品中文字幕电影 | 美女扒开内裤让男人捅视频| 日韩精品青青久久久久久| 中国美女看黄片| 曰老女人黄片| 欧美日韩亚洲综合一区二区三区_| 亚洲国产欧美网| 女生性感内裤真人,穿戴方法视频| 怎么达到女性高潮| 99热只有精品国产| 日本三级黄在线观看| 日韩 欧美 亚洲 中文字幕| 十分钟在线观看高清视频www| 日韩免费av在线播放| 嫁个100分男人电影在线观看| 免费在线观看视频国产中文字幕亚洲| 久久久国产精品麻豆| xxxhd国产人妻xxx| 亚洲,欧美精品.| 成熟少妇高潮喷水视频| 嫩草影视91久久| 高清毛片免费观看视频网站 | 美女大奶头视频| 最新在线观看一区二区三区| 伊人久久大香线蕉亚洲五| 久久香蕉激情| 成人av一区二区三区在线看| 青草久久国产| 亚洲精品在线美女| 青草久久国产| 999久久久精品免费观看国产| 国产精华一区二区三区| 国产亚洲av高清不卡| 久久天躁狠狠躁夜夜2o2o| 欧美精品亚洲一区二区| 国产精品久久久久久人妻精品电影| 在线十欧美十亚洲十日本专区| 一夜夜www| 国产免费男女视频| 国产伦人伦偷精品视频| 好看av亚洲va欧美ⅴa在| 黄色视频,在线免费观看| 麻豆一二三区av精品| 久久久久久久午夜电影 | 90打野战视频偷拍视频| 一级毛片精品| 国产亚洲欧美在线一区二区| 伦理电影免费视频| 1024香蕉在线观看| 国产日韩一区二区三区精品不卡| 国产一卡二卡三卡精品| 精品久久久久久成人av| 日韩成人在线观看一区二区三区| 黄色片一级片一级黄色片| 精品国产亚洲在线| 一边摸一边抽搐一进一小说| 九色亚洲精品在线播放| 高清黄色对白视频在线免费看| 欧美精品啪啪一区二区三区| 女生性感内裤真人,穿戴方法视频| xxx96com| 99热只有精品国产| 国产激情久久老熟女| 国产不卡一卡二| 久久久国产一区二区| 亚洲成人免费av在线播放| 精品国产一区二区久久| 国产一区二区三区视频了| 麻豆av在线久日| 亚洲va日本ⅴa欧美va伊人久久| 亚洲人成77777在线视频| 亚洲 欧美一区二区三区| 欧美黄色片欧美黄色片| 亚洲av片天天在线观看| 母亲3免费完整高清在线观看| 国产成人欧美| 欧美成人免费av一区二区三区| 99精品欧美一区二区三区四区| 香蕉久久夜色| 一区二区三区精品91| 国产av在哪里看| 黄色丝袜av网址大全| videosex国产| 九色亚洲精品在线播放| 三级毛片av免费| 国产高清激情床上av| 啦啦啦在线免费观看视频4| 免费女性裸体啪啪无遮挡网站| 丰满饥渴人妻一区二区三| 桃色一区二区三区在线观看| 欧美老熟妇乱子伦牲交| 美国免费a级毛片| 嫁个100分男人电影在线观看| av中文乱码字幕在线| 正在播放国产对白刺激| 黑丝袜美女国产一区| 又紧又爽又黄一区二区| 亚洲欧美激情综合另类| 一进一出好大好爽视频| 99久久99久久久精品蜜桃| 中国美女看黄片| 亚洲伊人色综图| 多毛熟女@视频| 国产一区二区激情短视频| 欧美日韩av久久| 国产国语露脸激情在线看| 久热这里只有精品99| 看黄色毛片网站| 1024视频免费在线观看| av天堂在线播放| 成人18禁高潮啪啪吃奶动态图| 亚洲九九香蕉| 动漫黄色视频在线观看| 精品久久蜜臀av无| 亚洲熟妇熟女久久| 手机成人av网站| 人人妻人人澡人人看| 国产免费av片在线观看野外av| 国产成人精品久久二区二区免费| 麻豆av在线久日| 国产男靠女视频免费网站| 久久人妻av系列| 久久人妻熟女aⅴ| 亚洲国产欧美日韩在线播放| 亚洲avbb在线观看| 国产免费现黄频在线看| 久热爱精品视频在线9| 99久久精品国产亚洲精品| 亚洲视频免费观看视频| 一本大道久久a久久精品| 男人操女人黄网站| 美女午夜性视频免费| 看片在线看免费视频| 中国美女看黄片| 久久人人精品亚洲av| 人人妻人人添人人爽欧美一区卜| 日本a在线网址| 999精品在线视频| 欧美另类亚洲清纯唯美| 成人亚洲精品一区在线观看| 亚洲三区欧美一区| 91麻豆av在线| 亚洲精品粉嫩美女一区| 一二三四在线观看免费中文在| 99久久精品国产亚洲精品| 99精品欧美一区二区三区四区| 岛国在线观看网站| 久99久视频精品免费| 另类亚洲欧美激情| 国产亚洲精品一区二区www| 亚洲色图 男人天堂 中文字幕| av在线播放免费不卡| 色播在线永久视频| 中文欧美无线码| av在线播放免费不卡| 亚洲av成人一区二区三| 久久性视频一级片| 亚洲第一av免费看| 免费一级毛片在线播放高清视频 | 搡老乐熟女国产| 久久久国产精品麻豆| 手机成人av网站| 国产色视频综合| 伊人久久大香线蕉亚洲五| 久久久精品国产亚洲av高清涩受| 婷婷精品国产亚洲av在线| 亚洲第一欧美日韩一区二区三区| 巨乳人妻的诱惑在线观看| 亚洲精品国产一区二区精华液| 1024香蕉在线观看| 日韩大尺度精品在线看网址 | 欧美成人性av电影在线观看| 麻豆成人av在线观看| 精品熟女少妇八av免费久了| 亚洲精品一区av在线观看| 日本三级黄在线观看| 久久精品影院6| 91在线观看av| 国产成人影院久久av| 国产一区在线观看成人免费|