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GTV delineation for NPC IJROBP49

doi:10.1016/S0360-3016(03)00405-X

CLINICAL INVESTIGATION Head and Neck

INTENSITY-MODULATED RADIATION THERAPY FOR HEAD-AND-NECK

CANCER:THE UCSF EXPERIENCE FOCUSING ON TARGET

VOLUME DELINEATION N ANCY L EE ,M.D.,*P ING X IA ,P H .D.,*N ANCY J.F ISCHBEIN ,M.D.,?P AM A KAZAWA ,C.M.D.,*

C LAYTON A KAZAWA ,C.M.D.,*AN

D J EANN

E M.Q UIVEY ,M.D.,F.A.C.R.*

Departments of *Radiation Oncology and ?Radiology,University of California-San Francisco,San Francisco,CA Purpose:To review the University of California-San Francisco (UCSF)experience of using intensity-modulated radiation therapy (IMRT)to treat head-and-neck cancer focusing on the importance of target volume delineation and adequate target volume coverage.

Methods and Materials:Between April 1995and January 2002,150histologically con?rmed patients underwent IMRT for their head-and-neck cancer at our institution.Sites included were nasopharynx 86,oropharynx 22,paranasal sinus 22,thyroid 6,oral tongue 3,nasal cavity 2,salivary 2,larynx 2,hypopharynx 1,lacrimal gland 1,skin 1,temporal bone 1,and trachea 1(Table 1).One hundred seven patients were treated de?nitively with IMRT ?concurrent platinum chemotherapy (92/107),whereas 43patients underwent gross surgical resection followed by postoperative IMRT ?concurrent platinum chemotherapy (15/43).IMRT was delivered using three different techniques:1)manually cut partial transmission blocks,2)computer-controlled auto-sequencing segmental multileaf collimator,and 3)sequential tomotherapy using dynamic multivane intensity-modulating collimator.Forty-two patients were treated with a forward plan,102patients with an inverse plan,and 6patients with both forward and inverse plans.The gross target volume (GTV)was de?ned as tumor detected on physical examination or imaging studies.In postoperative cases,the GTV was de?ned as the preoperative gross tumor volume.The clinical target volume (CTV)included all potential areas at risk for microscopic tumor involvement by either direct extension or nodal spread including a margin for patient motion and setup errors.The average prescription doses to the GTV were 70Gy and 66Gy for the primary and the postoperative cases,respectively.The site of recurrence was determined by the diagnostic neuroradiologist to be either within the GTV or the CTV volume by comparison of the treatment planning computed tomography with posttreatment imaging studies.Results:For the primary de?nitive cases with a median follow-up of 25months (range 6to 78months),4patients failed in the GTV.The 2-and 3-year local freedom from progression (LFFP)rates were 97%and 95%.With a median follow-up of 17months (range 8to 56months),7patients failed in the postoperative setting.The 2-year LFFP rate was 83%.For the primary group,the average maximum,mean,and minimum doses delivered were 80Gy,74Gy,56Gy to the GTV,and 80Gy,69Gy,33Gy to the CTV.An average of only 3%of the GTV and 3%of the CTV received less than 95%of the prescribed dose.For the postoperative group,the average maximum,mean,and minimum doses delivered were 79Gy,71Gy,37Gy to the GTV and 79Gy,66Gy,21Gy to the CTV.An average of only 6%of the GTV and 6%of the CTV received less than 95%of the prescribed dose.

Conclusion:Accurate target volume delineation in IMRT treatment for head-and-neck cancer is essential.Our multidisciplinary approach in target volume de?nition resulted in few recurrences with excellent LFFP rates and no marginal failures.Higher treatment failure rates were noted in the postoperative setting in which lower doses were prescribed.Potential dose escalation studies may further improve the local control rates in the postoperative setting.?2003Elsevier Inc.

IMRT,Head and neck,Target volume delineation,Patterns of failure.

INTRODUCTION

Head-and-neck cancers are ideal sites for intensity-modulated radiation therapy (IMRT)application because the tumors often occur in close proximity to multiple critical normal tissues such as the brainstem,optic chiasm,optic nerves,and the spinal

cord (1–10).In addition,because there is a lack of organ motion in the head-and-neck region,daily patient setups can be reproduced accurately,with adequate immobilization.Further-more,because head-and-neck cancer often presents in a locally advanced stage,dose escalation to the primary tumor using IMRT may result in an improvement in local control.

Reprint requests to:Nancy Lee,M.D.,Department of Radiation Oncology,Memorial Sloan-Kettering Cancer Center,1275York Avenue,Box 22,New York,NY 10021.Tel:(212)639-3342;Fax:(212)794-3188;E-mail:leen2@https://www.wendangku.net/doc/a76208436.html,

Presented at the American Society of Therapeutic Radiology and Oncology,44th Annual Meeting,October 2002,New Orleans,LA.Received Jan 16,2003,and in revised form Mar 10,2003.Accepted

for publication Mar 20,2003.

Int.J.Radiation Oncology Biol.Phys.,Vol.57,No.1,pp.49–60,2003

0360-3016/03/$–see front matter

IMRT,however,has a very sharp dose fall-off gradient between the target and surrounding normal tissue.This potential pitfall makes adequate target volume delineation absolutely essential(2,11,12).The treatment planning system will not treat areas not drawn on the computed tomographic(CT)slices,and the algorithm will even“work hard”to spare regions that are not contoured.Precise target volume delineation is dependent on a thorough physical examination and adequate imaging studies such as magnetic resonance imaging(MRI),especially near the skull base region.Given these issues,at the University of California San Francisco Medical Center,target volume delineation is done with a multidisciplinary team approach consisting of the radiation oncologist,the neuroradiologist,and,in the postoperative setting,the head-and-neck surgeon.The target volumes of each case are carefully and accurately de?ned jointly by the multidisciplinary team.The authors present a series of head-and-neck cancer patients treated with IMRT between1995and2002,focusing on the importance of target volume delineation.

METHODS AND MATERIALS

Patient and staging evaluation

Between April1995and January2002,150head-and-neck cancer patients were treated with IMRT in the Depart-ment of Radiation Oncology,University of California San Francisco;treatment was de?nitive in107patients and followed gross total resection in43patients.There were103 males and47females,with a mean age of53(range17to 85).Sites included were nasopharynx86,oropharynx22, paranasal sinus22,thyroid6,oral tongue3,nasal cavity2, salivary gland2,larynx2,hypopharynx1,lacrimal gland1, skin1,temporal bone1,and trachea1.There were78 Asians,63whites,4African-Americans,4Hispanics,and1 Saudi Arabian.Sixty-seven of these patients,all of whom had nasopharyngeal carcinoma,were previously reported (13).The current analysis updates the long-term outcome of all150patients including the previously reported67naso-pharyngeal carcinoma patients.

Pretreatment evaluation included a complete history and physical examination,direct?exible?beroptic endoscopic examination,complete blood count,liver function tests, chest X-ray,pathology review,MRI scans of the head and neck,and dental evaluation.Diagnostic CT scans of the head and neck and positron emission tomography(PET) scans were selectively done.Bone scans and CT scans of the abdomen and/or chest were obtained when clinically indi-cated.The disease was staged according to the2003Amer-ican Joint Committee on Cancer(AJCC)staging classi?ca-tion(14).

Radiation treatment

All patients received external beam radiation therapy. Twenty-seven nasopharyngeal cancer patients also had high-dose-rate intracavitary brachytherapy boost at the dis-cretion of the treating physician(13).Over the past8years, several different radiotherapy techniques and IMRT meth-ods have evolved.In our initial experience,only the primary tumor was treated with IMRT,whereas the upper neck above the vocal cords was irradiated with opposed-lateral ?elds and the lower neck and the supraclavicular fossae were treated with a single anterior?eld using conventional radiotherapy.The IMRT?eld was matched with the op-posed-lateral neck?eld with a split-beam technique.The opposed-lateral neck?eld was also matched to the lower neck and supraclavicular?eld with a split-beam technique. This technique was described previously and required the patient’s head to be hyperextended(6,13).

A second technique treated the primary and the upper neck above the vocal cords with IMRT and the lower neck and the supraclavicular fossae with an anterior?eld.These two?elds were matched with a split-beam technique.How-ever,concerns about dose uncertainties at the match lines

Table1.Patient characteristics

Tumor site Nasopharynx86

Oropharynx22

Larynx/Hypopharynx3

Paranasal sinus/Nasal cavity24

Thyroid6

Oral tongue3

Parotid1

Lacrimal gland1

Temporal bone1

Submandibular gland1

Skin/Cheek1

Trachea1

Histologies WHO II38

WHO III48

Squamous cell40

Esthesioneuroblastoma4

Sinonasal undifferentiated ca.7

Adenoid cystic carcinoma4

Adenocarcinoma2

Salivary2

Papillary3

Hurtle cell1

Anaplastic1

T-Stage T126%

T221%

T319%

T434%

N-Stage N033%

N125%

N236%

N36%

Overall stage I7%

II11%

III31%

IV51%

Median age53(17–85)

Race Asian78

White63

Hispanic4

Black4

Saudi Arabian1

Sex Male103

Female47

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led us to our third technique in which we used an extended-?eld IMRT that treated the primary tumor along with all the regional lymph nodes including the supraclavicular nodes.

A detailed description of each of the above techniques is presented elsewhere(6,15).

The prescribed dose was70Gy to the gross target volume (GTV)and positive neck nodes,60Gy to the clinical target volume(CTV)which included the GTV plus a margin of potential microscopic spread,and50–60Gy to the clini-cally negative nodal regions for the external beam radio-therapy.In general,the upper neck or the high-risk subclin-ical region received60Gy,whereas the low neck and the supraclavicular region received50–54Gy.Because our goal was to prescribe1.8Gy/fraction/day,5days/week to the CTV,the GTV received a higher dose per fraction, typically2.12Gy/fraction/day.

If intracavitary brachytherapy boost was used,it usually occurred1–2weeks after the external beam radiotherapy (13).For the primary cases,86%(92patients)received concurrent cis-platinum based chemotherapy vs.35%(15 patients)of the postoperative cases.For the nasopharyngeal carcinoma cases and the sinonasal undifferentiated carci-noma cases,postradiation adjuvant5-?uorouracil and cis-platinum chemotherapy was also given(16). Simulation,immobilization,and treatment planning

CT procedures

The patient’s head position was either hyperextended or neutral at the initial simulation at the discretion of the

treating physician.In some patients,hyperextension of the neck was not possible because of discomfort for the patient, and a neutral position was selected.The isocenter on the initial simulation?lm was placed at the anticipated treat-ment isocenter.The head,neck,and in some cases the shoulders were immobilized using a thermoplastic mask with the neck supported on a Timo cushion(MED-TEC) mounted on an S-type board that allows patient positioning to be indexed(S-type,MED-TEC,Orange City,Iowa).See Fig. 1.A pair of orthogonal radiographs was taken to con?rm isocenter localization.Treatment planning CT scans in serial3–5-mm slices from the head down through the clavicles were obtained.

Delineation of target volumes

Our target volume de?nition has slowly evolved over the past7years and was guided by standard radiation treatment portals;it included a substantial margin around the GTV and CTV because of concerns for potential marginal fail-ures.All target volumes were outlined slice by slice on the 3–5-mm treatment-planning CT images.The gross target volume(GTV)is de?ned as the gross extent of the primary tumor shown by imaging studies and physical examination as well as all grossly involved regional lymph nodes.Gross nodal disease was de?ned as focal nodal necrosis or heter-ogeneity,or as short axial diameter?10mm.The CTV is de?ned as the GTV plus a margin for potential direct routes of microscopic spread and clinically uninvolved regional lymph nodal regions.During the time that the patients in this series were treated,the planning system,Peacock or Corvus,did not allow speci?cation of asymmetric margin to the GTV or the CTV.Therefore,our GTV and CTV in-cluded a“built in”planning target volume(PTV)so as to account for patient setup errors.Further,the planning sys-tem did not allow for the GTV or CTV to overlap unin-volved critical adjacent tissues such as the optic nerves or chiasm,even if the physician planned to minimize the dose to these structures.Target volume de?nition in the vicinity of such critical organs was necessarily restrictive,and did not allow for generous margins.

Using nasopharyngeal carcinoma as a model(Fig.2)for the primary cases,the GTV(shown in red)delineation was done in consultation with the neuroradiologist with review of both diagnostic MRI and the corresponding treatment planning CT images to clearly identify the primary tumor, its local extension,and any involved lymph nodes;the location of critical adjacent structures including the brain-stem,spinal cord,parotid glands,temporomandibular joints, inner ear,and the optic nerves and chiasm were also care-fully noted.The CTV(shown in magenta)included the base of skull,pterygoid fossae,retropharyngeal nodal region, posterior third of the maxillary sinuses,the clivus,the sphenoid sinus,and at least the posterior third to sometimes one-half of the apparently uninvolved nasal cavity.The margin was,of necessity,minimal in critical areas such as adjacent to the brainstem,the optic nerves,and chiasm.

For Fig.1.Patient immobilization using the head-and-neck shoulder mask with the neck supported on a Timo cushion mounted on an S-type board that allows patient positioning to be indexed(S-type, MED-TEC).

Target volume delineation in IMRT for head-and-neck cancer●N.L EE et al.

the postoperative cases,the GTV was de ?ned as the preop-erative gross tumor volume and the CTV included the potential direct routes of microscopic spread as well as a margin to account for patient setup errors (Fig.3).Higher doses to the skin may occur in situations where there are grossly positive lymph nodes close to the skin as seen in Fig.3(17).

The coverage for the CTV of the neck is dependent on the primary disease site as well as the extent of disease.When doubt arises regarding appropriate CTV coverage for the neck,the lymph nodal regions included in the traditional opposed lateral ?elds should be referenced.The following is a general description of our approach toward our neck CTV de ?nition.There are several nodal classi ?cations that have been proposed,and it is our preference to use the nodal classi ?cation presented by Som et al.(18).Retropharyngeal lymph nodal regions,Levels I –V,and the supraclavicular nodes are routinely covered for all our nasopharyngeal cases.These nodal regions in general also apply for our oropharyngeal,hypopharyngeal,advanced laryngeal,

and

Fig.2.An example of a target volume delineation for a de ?nitive case,a patient with T3N0nasopharyngeal carcinoma:(a)axial,(b)sagittal,(c)coronal,(d)DVH.The GTV is shown in red,and the CTV is shown in magenta.

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oral cavity lesions.For paranasal sinus tumors,regional lymph nodes were not included unless the tumor was high-grade,high-stage,or there was documented biopsy proven nodal involvement.Experts around the world are collabo-rating to de ?ne a consensus statement regarding appropriate and adequate CTV coverage for both the node-positive as well as the node-negative neck.Until then,it is the authors ’opinion that a more generous coverage of the neck CTV to ensure no marginal misses is necessary.Treatment planning and delivery

Two different treatment planning software systems were used.In our earlier experience,we used a modi ?ed CT-based planning system developed at the University of Mich-igan (U-M Plan)(19).Over time,we found that there was a signi ?cant further advantage in dose optimization using inverse treatment-planning systems developed by the NO-MOS Corporation,i.e.,the Peacock,Version 1,or Corvus,Version 3.0and Version 4.0planning systems (20).

Cur-

Fig.3.An example of the target volume delineation for a postoperative case,a patient with T4N0poorly differentiated thyroid carcinoma:(a)axial,(b)sagittal,(c)coronal,(d)DVH.The preoperative GTV is shown in red,and the CTV is shown in magenta.The purple colorwash represents a pseudovolume that is designed to force the algorithm to minimize overtreatment of posterior neck tissues.

Target volume delineation in IMRT for head-and-neck cancer

●N.L EE et al.

rently,we are using Corvus Version4.6.Treatment was delivered using either manually cut partial transmission blocks or a computer-controlled auto-sequence multileaf collimator(MLC)system(Siemens Medical Systems,Con-cord,CA),or the MIMiC when using the Peacock plan(20), and a dynamic MLC system(Varian Oncology Systems, Palo Alto,CA).The treatment planning and delivery details have been described previously(6).

Dose–volume histogram(DVH)analysis on target volumes

Forty-three patients were planned with a forward plan (FP)and101with an inverse plan(IP).Six patients received part of their treatment with a FP and part of their treatment with an IP.DVHs of the GTV and CTV and the critical normal structures,such as the brainstem,spinal cord,chi-asm,optic nerves,middle and inner ears,temporomandib-ular joints,and the parotid glands were retrospectively re-trieved from our planning CT scans and analyzed accordingly.A total of148patients were included in this part of the analysis.Data were not available for2patients. For GTV and CTV,we evaluated the volume receiving less than95%of the prescribed dose as quantitative end-points to re?ect the tumor target coverage.The maximum dose,minimum dose,and the mean dose to the target volumes were also calculated.For the critical organs with functional subunits organized in series such as the brain-stem,spinal cord,chiasm,and optic nerves,the maximum doses were examined.For critical organs with functional subunits organized in parallel such as the parotids,temporo-mandibular joints,and the middle and inner ears,the dose delivered to50%volume was examined.

Follow-up

All the patients were evaluated at least once a week during radiotherapy.The patients were then evaluated every 1–2months for the?rst6months,followed by every3 months for the next6–12months,every4–6months from 18months through3years,and annually thereafter.At each follow-up visit,a physical examination,including a direct ?exible?beroptic endoscopy examination,and palpation of the neck was performed.A baseline posttreatment MRI scan of the nasopharynx and neck was obtained within2–6 months after completion of radiotherapy and then yearly or when clinically indicated.A PET scan was also obtained in some patients during follow-up,generally at least4months after therapy.Acute and late normal tissue effects were graded according to the Radiation Therapy Oncology Group (RTOG)radiation morbidity scoring criteria.

Analysis of failure

The site of recurrence was determined by the diagnostic radiologist to be either within the GTV,the CTV,or mar-ginal by comparison of the treatment planning CT with posttreatment imaging studies.Statistical methods

Descriptive statistics(mean,median,proportions)were calculated to characterize the patient,disease,and treatment features as well as toxicities after IMRT.The probability of failure due to locally recurrent disease,distant metastasis, and death were estimated using the Kaplan-Meier product-limit method.Durations were calculated from the date of diagnosis.

RESULTS

Treatment outcomes

With a median follow-up of21months for the entire series of150patients(range6to78months),there were10 treatment failures in the GTV,(of which6were in the postoperative setting),and1patient failed in the CTV. There have been no marginal failures observed.The overall 2-and3-year local freedom from progression(LFFP)rates were94%and87%,respectively(Table2).

For the107primary cases with a median follow-up of25 months(range6to78months),only four failures have been detected in the GTV,and none were in the CTV.Two T4 nasopharyngeal carcinoma patients and one T4b tonsil car-cinoma patient developed local recurrence in the primary site.One patient with base of tongue carcinoma(T1N1) failed in a grossly positive node after de?nitive chemother-apy and radiotherapy.No marginal failures have been ob-served to date.The2-and3-year LFFP rates were97%and 95%(Fig.4).The2-and3-year overall survival for the primary de?nitive cases is shown in Fig.5.Figure6is an example of a patient who failed within the GTV.The patient presented with T4bN1squamous cell carcinoma of the right tonsillar fossa.There was parapharyngeal and prevertebral involvement on presentation.The patient underwent a course of cis-platinum chemotherapy concurrent with IMRT.Approximately7months after radiotherapy,after an initial clinical and radiographic response,the patient devel-oped local recurrence and died with autopsy-con?rmed re-current invasive squamous cell carcinoma.

For the43patients in the postoperative setting,with a median follow-up of17months(range8to56months),7 patients developed locoregional failures.Of these failures,6of 7occurred in patients with T4paranasal sinus cancer(2si-nonasal undifferentiated carcinoma,2squamous cell carci-noma,1adenocarcinoma,1esthesioneuroblastoma);1patient had oral tongue cancer(T1N2b).The2-year LFFP was83% (Fig.7)and the2-year overall survival was83%(Fig.8).No marginal failures have been observed to date in this group.

Table2.Overall local freedom from progression rates

n?150Local FFP 2year94%(87–97%) 3year87%(76–93%) Abbreviation:FFP?freedom from progression.

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Dose –volume analysis

With regard to the target volumes,for the de ?nitive group,the average maximum,mean,and minimum doses delivered were 80Gy,74Gy,56Gy to the GTV and 80Gy,69Gy,33Gy to the CTV.An average of only 3%of the GTV and 3%of the CTV received less than 95%of the prescribed dose.For the postoperative group,the average maximum,mean,and minimum doses delivered were 79Gy,71Gy,37Gy to the GTV and 79Gy,66Gy,21Gy to the CTV.An average of only 6%of the GTV and 6%of the CTV received less than 95%of the prescribed dose.The majority of the GTV and CTV actually received more than 105%of the prescribed dose.It should be noted that the maximum and minimum

doses

Fig.4.Kaplan-Meier estimates of local freedom from progression rates for the de ?nitive

cases.

Fig.5.Kaplan-Meier estimates of overall survival rates for the de ?nitive cases.

Target volume delineation in IMRT for head-and-neck cancer

●N.L EE et al.

are point doses,although the maximum dose described by the International Commission on Radiation Units and Measurements Report No.50is the region encompassed by a 2-cm area.With regard to normal tissue doses (Table 3),there was signi ?cant sparing of all critical structures without compro-mising tumor target coverage.Dose to these critical organs would be signi ?cantly higher if conventional

radiotherapy

Fig.6.(a)An example of an “in-?eld ”failure,a patient with T4bN1carcinoma of the tonsillar fossa.An axial slice of a MR image of the gross tumor and the axial slice of the treatment planning CT.(b)On the left,an axial slice of a MR image taken 2months after IMRT and on the right,an axial slice of a MR image showing the site of recurrence 7months after IMRT.Notice that the MR image at 7months shows progressive soft tissue abnormality in the carotid sheath.

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were used.The results of the quantitative analyses of the DVHs for the tumor target and critical structures were consistent with the observed clinical results of excellent local control without any observed increase in late normal tissue toxicity.Maximum doses to the optic chiasm and brainstem were 33and 50Gy,respectively.Mean left and right parotid doses were both 29Gy.Of note,excellent target coverage with a high dose could be achieved with either a forward plan or an inverse plan method.We found that the inverse plan method delivered lower doses to the surrounding normal tissues than the forward plan method which was used before 1997

(6).

Fig.7.Kaplan-Meier estimates of local freedom from progression rates for the postoperative

cases.

Fig.8.Kaplan-Meier estimates of overall survival rates for the postoperative cases.

Target volume delineation in IMRT for head-and-neck cancer

●N.L EE et al.

Acute and late toxicity

Acute side effects of radiation therapy?chemotherapy were well tolerated.The most common acute toxicities were mucositis and/or pharyngitis,sometimes requiring gastros-tomies to ensure adequate nutrition.Four patients had Grade 3dermatitis.

The late normal tissue effects were scored according to the RTOG criteria.The most common late effect was xe-rostomia,which appeared to decrease with time after IMRT, generally by2years.Other late toxicities observed included hearing impairment in6patients(all of whom had chemo-therapy),soft tissue necrosis,subcutaneous?brosis,neurop-athy,nasopharyngeal stenosis,temporomandibular joint pain on chewing,trismus,and focal osteonecrosis of a prominent torus.One patient experienced intermittent neu-ralgia.

DISCUSSION

As we enter the era of highly conformal radiotherapy, radiation oncologists are faced with a dilemma:what ex-actly needs to be included in the treatment volume?Differ-ent guidelines have been proposed regarding this issue(10, 12,21–23).There can be signi?cant inter-physician vari-ability in producing target volumes and radiation treatment plans for conformal radiotherapy.One study comparing target volumes delineated by three diagnostic radiologists and eight radiation oncologists showed up to a threefold variation in volumes outlined by different clinicians(11). Inadequate coverage in the treatment volume can result in tumor recurrence,which is of course an undesirable out-come and the worst complication that a patient can experi-ence.Therefore,adequate delineation of the target volumes is absolutely crucial to the IMRT treatment planning pro-cess.The differences in target volume de?nition among physicians can lead to overall uncertainty in the analysis of outcome data for conformal radiotherapy planning.To min-imize such variability,GTV de?nition should be done in a multidisciplinary fashion with a team consisting of a radi-ation oncologist,a neuroradiologist,and whenever neces-sary,a head-and-neck surgeon,particularly in the postop-erative setting.

The de?nition of the CTV is the major dif?culty that the radiation oncologist will face in IMRT treatment planning: what exactly should the physician outline on the treatment planning CT scans to ensure that all the areas of potential microscopic spread are adequately included?Recently,sev-eral papers examining the precise de?nition of the nodal levels of the head-and-neck region have been published(18, 24–27).These nodal atlas guidelines are helpful to the radiation oncologists in delineating CTV during treatment planning.However these atlases,whether anatomy based (24,27)or imaging based(18,25,26),are limited because their primary focus is on the delineation of the lymph nodal levels for the normal neck.Distortion of the normal head-and-neck anatomy can occur when there is surgical viola-tion or when there is gross disease involvement of adjacent tissues such as muscles.Because of concerns for marginal failure,our CTV de?nition has been guided by standard conventional radiation treatment portals to include a sub-stantial margin around the GTV plus a margin for potential direct routes of microscopic spread and coverage of appar-ently uninvolved lymph nodes.This practice seems to have been successful in preventing subsequent marginal tumor recurrences.

Chao et al.(22)reported their experience of126head-and-neck cancer patients treated with IMRT and proposed guidelines for target volume determination and delineation. Their guidelines were based on the location of the primary tumor site and its probability of microscopic metastasis to the ipsilateral and contralateral(Level I–V)lymph nodal regions.For the primary cases,CTV1included gross tumor and region adjacent to the tumor but not directly involved by tumor,whereas CTV1in the postoperative cases in-cluded the preoperative GTV plus a2-cm margin.CTV2for both the de?nitive and postoperative cases encompassed the uninvolved cervical lymph nodal regions.CTV was larger in patients with gross nodes or those with extracapsular extension than in those patients who did not have gross nodal involvement or extracapsular extension in both the primary and postoperative cases,respectively.With a me-dian follow-up of26months,there were6of52(12%) de?nitive cases with persistent or recurrent nodal disease and7of74(9%)postoperative cases with failure in the nodal region.There was only one failure marginal to CTV1, but this was an in-?eld failure of CTV2.There were two failures marginal to CTV2.

The experience of Dawson et al.(21)treating58head-and-neck cancer patients using a3D planning system de-veloped at the University of Michigan also concluded that the majority of local-regional recurrences were“in-?eld.”

Table3.Dose–volume statistics derived from dose–volume

histograms for normal tissues

Organ Maximum dose

(Gy)

Average(range)

Mean dose

(Gy)

Average(range)

Brainstem50(13–67)

Spinal cord41(9–50)

Chiasm33(1–56)

Optic nerves

Right31(1–68)

Left31(2–65)

Eye

Right32(1–69)

Left31(1–65)

Parotid glands

Right30(8–72)

Left29(7–60)

Ear

Right42(7–74)

Left41(7–64)

Temporomandibular joint

Right45(13–79)

Left45(13–78)

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With a median follow-up of27months,the2-year actuarial local-regional control rate was79%.Ten patients(80%) recurred“in-?eld”and2patients relapsed marginally.Re-currences were in areas judged to be at high risk at the time of radiation treatment planning,including the GTV,the operative bed,and the high-risk nodal groups.The GTV was de?ned as the gross primary and nodal tumor,whereas the CTV was de?ned as1-to2-cm expansion around each the GTV and nondissected nodal groups with a greater than 10–15%risk of containing subclinical disease.The PTV contained an automated0.3–0.5cm3D expansion of the CTV surfaces to account for setup error.

Several factors could explain our excellent locoregional control rates.Approximately60%of our patients had naso-pharyngeal carcinoma,a radiosensitive tumor(16,28–30) In addition,71%of our patients received concurrent che-motherapy,which has been shown to improve control rates as well as survival(16,31).Our data also show that with accurate target delineation,high local control can be achieved with signi?cant sparing of the normal tissue.The fact that no marginal failures have been observed to date is most likely due to the fact that our target volume de?nition is quite generous,but it has been brought to our attention that we might be overtreating our patients.Although that may be true,thus far,no increase in long-term complica-tions has been observed.It is the authors’opinion that the worst complication that a patient can experience is tumor recurrence and that generous target delineation in IMRT, guided by high-quality imaging and an understanding of the patterns of spread of disease,is preferable to treatment failure.Perhaps radiation oncologists,neuroradiologists, and head-and-neck surgeons should join together to draw up a consensus on the selection and delineation of target vol-ume for IMRT treatment planning.

CONCLUSION

Adequate target volume delineation in IMRT treatment for head-and-neck cancer is essential.Our multidisciplinary approach in target volume de?nition resulted in few recur-rences with excellent LFFP rates and no marginal failures. Higher treatment failure rates were noted in the postopera-tive setting.Potential dose escalation studies may further improve the local control rates in the postoperative setting.

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60I.J.Radiation Oncology●Biology●Physics Volume57,Number1,2003

to与for的用法和区别

to与for的用法和区别一般情况下, to后面常接对象; for后面表示原因与目的为多。 Thank you for helping me. Thanks to all of you. to sb.表示对某人有直接影响比如，食物对某人好或者不好就用to; for表示从意义、价值等间接角度来说，例如对某人而言是重要的，就用for. for和to这两个介词，意义丰富，用法复杂。这里仅就它们主要用法进行比较。 1. 表示各种“目的” 1. What do you study English for? 你为什么要学英语？ 2. She went to france for holiday. 她到法国度假去了。 3. These books are written for pupils. 这些书是为学生些的。 4. hope for the best, prepare for the worst. 作最好的打算，作最坏的准备。 2．对于 1．She has a liking for painting. 她爱好绘画。 2．She had a natural gift for teaching. 她对教学有天赋/ 3．表示赞成同情，用for不用to. 1. Are you for the idea or against it? 你是支持还是反对这个想法？ 2. He expresses sympathy for the common people.. 他表现了对普通老百姓的同情。 3. I felt deeply sorry for my friend who was very ill. 4 for表示因为，由于（常有较活译法） 1 Thank you for coming. 谢谢你来。 2. France is famous for its wines. 法国因酒而出名。 5．当事人对某事的主观看法，对于（某人），对…来说（多和形容词连用）用介词to，不用for.. He said that money was not important to him. 他说钱对他并不重要。 To her it was rather unusual. 对她来说这是相当不寻常的。 They are cruel to animals. 他们对动物很残忍。 6．for和fit, good, bad, useful, suitable 等形容词连用，表示适宜，适合。 Some training will make them fit for the job. 经过一段训练，他们会胜任这项工作的。 Exercises are good for health. 锻炼有益于健康。 Smoking and drinking are bad for health. 抽烟喝酒对健康有害。 You are not suited for the kind of work you are doing. 7. for表示不定式逻辑上的主语，可以用在主语、表语、状语、定语中。 1．It would be best for you to write to him. 2．The simple thing is for him to resign at once. 3．There was nowhere else for me to go. 4．He opened a door and stood aside for her to pass.

of与for的用法以及区别

of与for的用法以及区别 for 表原因、目的 of 表从属关系介词of的用法（1）所有关系 this is a picture of a classroom （2）部分关系 a piece of paper a cup of tea a glass of water a bottle of milk what kind of football，American of soccer？（3）描写关系 a man of thirty 三十岁的人 a man of shanghai 上海人（4）承受动作 the exploitation of man by man．人对人的剥削。（5）同位关系 It was a cold spring morning in the city of London in England．（6）关于，对于 What do you think of Chinese food？你觉得中国食品怎么样？介词 for 的用法小结 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。What will we have for supper? 我们晚餐吃什么?

2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 Thank you for your last letter. 谢谢你上次的来信。 Thank you for teaching us so well. 感谢你如此尽心地教我们。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如: I usually do the running for an hour in the morning. 我早晨通常跑步一小时。We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如: Who are you waiting for? 你在等谁? For example, Mr Green is a kind teacher. 比如,格林先生是一位心地善良的老师。

常用介词用法(for to with of)

For的用法 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。 What will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如: I usually do the running for an hour in the morning. 我早晨通常跑步一小时。 We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如: Who are you waiting for? 你在等谁? For example, Mr Green is a kind teacher. 比如,格林先生是一位心地善良的老师。尽管for 的用法较多，但记住常用的几个就可以了。 to的用法: 一：表示相对，针对 be strange (common, new, familiar, peculiar) to This injection will make you immune to infection. 二：表示对比，比较 1：以-ior结尾的形容词，后接介词to表示比较，如：superior ,inferior,prior,senior,junior 2: 一些本身就含有比较或比拟意思的形容词，如equal，similar，equivalent，analogous A is similar to B in many ways.

(完整版)介词for用法归纳

介词for用法归纳用法1：(表目的)为了。如： They went out for a walk. 他们出去散步了。 What did you do that for? 你干吗这样做？ That’s what we’re here for. 这正是我们来的目的。 What’s she gone for this time? 她这次去干什么去了？ He was waiting for the bus. 他在等公共汽车。【用法说明】在通常情况下，英语不用for doing sth 来表示目的。如：他去那儿看他叔叔。误：He went there for seeing his uncle. 正：He went there to see his uncle. 但是，若一个动名词已名词化，则可与for 连用表目的。如： He went there for swimming. 他去那儿游泳。(swimming 已名词化) 注意：若不是表目的，而是表原因、用途等，则其后可接动名词。(见下面的有关用法) 用法2：(表利益)为，为了。如： What can I do for you? 你想要我什么？ We study hard for our motherland. 我们为祖国努力学习。 Would you please carry this for me? 请你替我提这个东西好吗？ Do more exercise for the good of your health. 为了健康你要多运动。【用法说明】(1) 有些后接双宾语的动词(如buy, choose, cook, fetch, find, get, order, prepare, sing, spare 等)，当双宾语易位时，通常用for 来引出间接宾语，表示间接宾语为受益者。如： She made her daughter a dress. / She made a dress for her daughter. 她为她女儿做了件连衣裙。 He cooked us some potatoes. / He cooked some potatoes for us. 他为我们煮了些土豆。注意，类似下面这样的句子必须用for： He bought a new chair for the office. 他为办公室买了张新办公椅。 (2) 注意不要按汉语字面意思，在一些及物动词后误加介词for：他们决定在电视上为他们的新产品打广告。误：They decided to advertise for their new product on TV. 正：They decided to advertise their new product on TV. 注：advertise 可用作及物或不及物动词，但含义不同：advertise sth＝为卖出某物而打广告；advertise for sth＝为寻找某物而打广告。如：advertise for a job=登广告求职。由于受汉语“为”的影响，而此处误加了介词for。类似地，汉语中的“为人民服务”，说成英语是serve the people，而不是serve for the people，“为某人的死报仇”，说成英语是avenge sb’s death，而不是avenge for sb’s death，等等。用法3：(表用途)用于，用来。如： Knives are used for cutting things. 小刀是用来切东西的。 This knife is for cutting bread. 这把小刀是用于切面包的。 It’s a machine for slicing bread. 这是切面包的机器。 The doctor gave her some medicine for her cold. 医生给了她一些感冒药。用法4：为得到，为拿到，为取得。如： He went home for his book. 他回家拿书。 He went to his friend for advice. 他去向朋友请教。 She often asked her parents for money. 她经常向父母要钱。

of和for的用法

of 1....的,属于 One of the legs of the table is broken. 桌子的一条腿坏了。 Mr.Brown is a friend of mine. 布朗先生是我的朋友。 2.用...做成的;由...制成 The house is of stone. 这房子是石建的。 3.含有...的;装有...的 4....之中的;...的成员 Of all the students in this class,Tom is the best. 在这个班级中,汤姆是最优秀的。 5.(表示同位) He came to New York at the age of ten. 他在十岁时来到纽约。 6.(表示宾格关系) He gave a lecture on the use of solar energy. 他就太阳能的利用作了一场讲演。 7.(表示主格关系) We waited for the arrival of the next bus. 我们等待下一班汽车的到来。

I have the complete works of Shakespeare. 我有莎士比亚全集。 8.来自...的;出自 He was a graduate of the University of Hawaii. 他是夏威夷大学的毕业生。 9.因为 Her son died of hepatitis. 她儿子因患肝炎而死。 10.在...方面 My aunt is hard of hearing. 我姑妈耳朵有点聋。 11.【美】(时间)在...之前 12.(表示具有某种性质) It is a matter of importance. 这是一件重要的事。 For 1.为,为了 They fought for national independence. 他们为民族独立而战。 This letter is for you. 这是你的信。

for和to区别

1.表示各种“目的”，用for （1）What do you study English for 你为什么要学英语？（2）went to france for holiday. 她到法国度假去了。（3）These books are written for pupils. 这些书是为学生些的。（4）hope for the best, prepare for the worst. 作最好的打算，作最坏的准备。 2．“对于”用for （1）She has a liking for painting. 她爱好绘画。（2）She had a natural gift for teaching. 她对教学有天赋/ 3．表示“赞成、同情”，用for （1）Are you for the idea or against it 你是支持还是反对这个想法？（2）He expresses sympathy for the common people.. 他表现了对普通老百姓的同情。（3）I felt deeply sorry for my friend who was very ill. 4. 表示“因为，由于”（常有较活译法），用for （1）Thank you for coming. 谢谢你来。

（2）France is famous for its wines. 法国因酒而出名。 5．当事人对某事的主观看法，“对于（某人），对…来说”，（多和形容词连用），用介词to，不用for. （1）He said that money was not important to him. 他说钱对他并不重要。（2）To her it was rather unusual. 对她来说这是相当不寻常的。（3）They are cruel to animals. 他们对动物很残忍。 6．和fit, good, bad, useful, suitable 等形容词连用，表示“适宜，适合”，用for。（1）Some training will make them fit for the job. 经过一段训练，他们会胜任这项工作的。（2）Exercises are good for health. 锻炼有益于健康。（3）Smoking and drinking are bad for health. 抽烟喝酒对健康有害。（4）You are not suited for the kind of work you are doing. 7. 表示不定式逻辑上的主语，可以用在主语、表语、状语、定语中。（1）It would be best for you to write to him. （2） The simple thing is for him to resign at once.

双宾语 to for的用法

1.两者都可以引出间接宾语，但要根据不同的动词分别选用介词to 或for：(1) 在give, pass, hand, lend, send, tell, bring, show, pay, read, return, write, offer, teach, throw 等之后接介词to。如：请把那本字典递给我。正：Please hand me that dictionary. 正：Please hand that dictionary to me. 她去年教我们的音乐。正：She taught us music last year. 正：She taught music to us last year. (2) 在buy, make, get, order, cook, sing, fetch, play, find, paint, choose,prepare, spare 等之后用介词for 。如：他为我们唱了首英语歌。正：He sang us an English song. 正：He sang an English song for us. 请帮我把钥匙找到。正：Please find me the keys. 正：Please find the keys for me. 能耽搁你几分钟吗(即你能为我抽出几分钟吗)? 正：Can you spare me a few minutes? 正：Can you spare a few minutes for me? 注：有的动词由于搭配和含义的不同，用介词to 或for 都是可能的。如：do sb a favour＝do a favour for sb 帮某人的忙 do sb harm＝do harm to sb 对某人有害

双宾语tofor的用法

1. 两者都可以引出间接宾语，但要根据不同的动词分别选用介词to 或for： (1) 在give, pass, hand, lend, send, tell, bring, show, pay, read, return, write, offer, teach, throw 等之后接介词to。如：请把那本字典递给我。正：Please hand me that dictionary. 正：Please hand that dictionary to me. 她去年教我们的音乐。正：She taught us music last year. 正：She taught music to us last year. (2) 在buy, make, get, order, cook, sing, fetch, play, find, paint, choose,prepare, spare 等之后用介词for 。如：他为我们唱了首英语歌。正：He sang us an English song. 正：He sang an English song for us. 请帮我把钥匙找到。正：Please find me the keys. 正：Please find the keys for me. 能耽搁你几分钟吗(即你能为我抽出几分钟吗)? 正：Can you spare me a few minutes? 正：Can you spare a few minutes for me? 注：有的动词由于搭配和含义的不同，用介词to 或for 都是可能的。如： do sb a favou r do a favour for sb 帮某人的忙 do sb harnn= do harm to sb 对某人有害

for和of的用法

for的用法： 1. 表示“当作、作为”。如: I like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。 What will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 Thank you for your last letter. 谢谢你上次的来信。 Thank you for teaching us so well. 感谢你如此尽心地教我们。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 4. 表示时间、距离,意为“计、达”。如:

I usually do the running for an hour in the morning. 我早晨通常跑步一小时。 We will stay there for two days. 我们将在那里逗留两天。 5. 表示去向、目的,意为“向、往、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 I paid twenty yuan for the dictionary. 我花了20元买这本词典。 6. 表示所属关系或用途,意为“为、适于……的”。如: It’s time for school. 到上学的时间了。 Here is a letter for you. 这儿有你的一封信。 7. 表示“支持、赞成”。如: Are you for this plan or against it? 你是支持还是反对这个计划? 8. 用于一些固定搭配中。如:

英语形容词和of for 的用法

加入收藏夹主题：介词试题It’s + 形容词 + of sb. to do sth.和It’s + 形容词 + for sb. to do sth.的用法区别。内容： It's very nice___pictures for me. A.of you to draw B.for you to draw C.for you drawing C.of you drawing 提交人：杨天若时间：1/23/2008 20:5:54 主题：for 与of 的辨别内容：It's very nice___pictures for me. A.of you to draw B.for you to draw C.for you drawing C.of you drawing 答：选A 解析：该题考查的句型It’s + 形容词+ of sb. to do sth.和It’s +形容词+ for sb. to do sth.的用法区别。 “It’s + 形容词+ to do sth.”中常用of或for引出不定式的行为者，究竟用of sb.还是用for sb.，取决于前面的形容词。 1) 若形容词是描述不定式行为者的性格、品质的，如kind，good，nice，right，wrong，clever，careless，polite，foolish等，用of sb. 例： It’s very kind of you to help me. 你能帮我，真好。 It’s clever of you to work out the maths problem. 你真聪明，解出了这道数学题。 2) 若形容词仅仅是描述事物，不是对不定式行为者的品格进行评价，用for sb.，这类形容词有difficult，easy，hard，important，dangerous，（im）possible等。例： It’s very dangerous for children to cross the busy street. 对孩子们来说，穿过繁忙的街道很危险。 It’s difficult for u s to finish the work. 对我们来说，完成这项工作很困难。 for 与of 的辨别方法：用介词后面的代词作主语，用介词前边的形容词作表语，造个句子。如果道理上通顺用of，不通则用for. 如： You are nice.(通顺，所以应用of)。 He is hard.(人是困难的，不通，因此应用for.) 由此可知，该题的正确答案应该为A项。提交人：f7_liyf 时间：1/24/2008 11:18:42

to和for的用法有什么不同(一)

to和for的用法有什么不同（一）一、引出间接宾语时的区别两者都可以引出间接宾语，但要根据不同的动词分别选用介词to 或for，具体应注意以下三种情况： 1. 在give, pass, hand, lend, send, tell, bring, show, pay, read, return, write, offer, teach, throw 等之后接介词to。如：请把那本字典递给我。正：Please hand me that dictionary. 正：Please hand that dictionary to me. 她去年教我们的音乐。正：She taught us music last year. 正：She taught music to us last year. 2. 在buy, make, get, order, cook, sing, fetch, play, find, paint, choose, prepare, spare 等之后用介词for 。如：他为我们唱了首英语歌。正：He sang us an English song. 正：He sang an English song for us. 请帮我把钥匙找到。正：Please find me the keys. 正：Please find the keys for me. 能耽搁你几分钟吗(即你能为我抽出几分钟吗)? 正：Can you spare me a few minutes?

正：Can you spare a few minutes for me? 3. 有的动词由于用法和含义不同，用介词to 或for 都是可能的。如： do sb a favor＝do a favor for sb 帮某人的忙 do sb harm＝do harm to sb 对某人有害在有的情况下，可能既不用for 也不用to，而用其他的介词。如： play sb a trick＝play a trick on sb 作弄某人请比较： play sb some folk songs＝play some folk songs for sb 给某人演奏民歌有时同一个动词，由于用法不同，所搭配的介词也可能不同，如leave sbsth 这一结构，若表示一般意义的为某人留下某物，则用介词for 引出间接宾语，即说leave sth for sb；若表示某人死后遗留下某物，则用介词to 引出间接宾语，即说leave sth to sb。如： Would you like to leave him a message? / Would you like to leave a message for him? 你要不要给他留个话？ Her father left her a large fortune. / Her father left a large fortune to her. 她父亲死后给她留下了一大笔财产。二、表示目标或方向的区别两者均可表示目标、目的地、方向等，此时也要根据不同动词分别对待。如： 1. 在come, go, walk, move, fly, ride, drive, march, return 等动词之后通常用介词to 表示目标或目的地。如： He has gone to Shanghai. 他到上海去了。 They walked to a river. 他们走到一条河边。

202X中考英语：to和for的区别与用法.doc

202X中考英语：to和for的区别与用法中考栏目我为考生们整理了“202X中考英语：to和for的区别与用法”，希望能帮到大家，想了解更多考试资讯，本网站的及时更新哦。 202X中考英语：to和for的区别与用法 to和for的区别与用法是什么一般情况下, to后面常接对象; for后面表示原因与目的为多。 Thank you for helping me. Thanks to all of you. to sb. 表示对某人有直接影响比如，食物对某人好或者不好就用to; for 表示从意义、价值等间接角度来说，例如对某人而言是重要的，就用for. for和to这两个介词，意义丰富，用法复杂。这里仅就它们主要用法进行比较。 1. 表示各种“目的” 1. What do you study English for? 你为什么要学英语? 2. She went to france for holiday. 她到法国度假去了。 3. These books are written for pupils. 这些书是为学生些的。 4. hope for the best, prepare for the worst. 作最好的打算，作最坏的准备。

2.对于 1.She has a liking for painting. 她爱好绘画。 2.She had a natural gift for teaching. 她对教学有天赋。 3.表示赞成同情，用for不用to. 1. Are you for the idea or against it? 你是支持还是反对这个想法? 2. He expresses sympathy for the common people.. 他表现了对普通老百姓的同情。 3. I felt deeply sorry for my friend who was very ill. 4 for表示因为，由于(常有较活译法) 1.Thank you for coming. 谢谢你来。 2. France is famous for its wines. 法国因酒而出名。 5.当事人对某事的主观看法，对于(某人)，对?来说(多和形容词连用)用介词to，不用for.. He said that money was not important to him. 他说钱对他并不重要。 To her it was rather unusual. 对她来说这是相当不寻常的。 They are cruel to animals. 他们对动物很残忍。

keep的用法及of 、for sb.句型区别

keep的用法 1. 用作及物动词 ①意为"保存；保留；保持；保守"。如： Could you keep these letters for me, please? 你能替我保存这些信吗？ ②意为"遵守；维护"。如： Everyone must keep the rules. 人人必须遵守规章制度。 The teacher is keeping order in class.老师正在课堂上维持秩序。 ③意为"使……保持某种(状态、位置或动作等)"。这时要在keep的宾语后接补足语，构成复合宾语。其中宾语补足语通常由形容词、副词、介词短语、现在分词和过去分词等充当。如：例：We should keep our classroom clean and tidy.(形容词) 我们应保持教室整洁干净。 You'd better keep the child away from the fire.(副词)你最好让孩子离火远一点。 The bad weather keeps us inside the house.(介词短语)坏天气使我们不能出门。 Don't keep me waiting for long.(现在分词)别让我等太久。 The other students in the class keep their eyes closed.(过去分词) 班上其他同学都闭着眼睛。 2. 用作连系动词构成系表结构：keep＋表语，意为"保持，继续(处于某种状态)"。其中表语可用形容词、副词、介词短语等充当。如：例：You must look after yourself and keep healthy.(形容词) 你必须照顾好自己，保持身体健康。 Keep off the grass.(副词)请勿践踏草地。 Traffic in Britain keeps to the left.(介词短语)英国的交通是靠左边行驶的。注意：一般情况下，keep后接形容词较为多见。再如： She knew she must keep calm.她知道她必须保持镇静。 Please keep silent in class.课堂上请保持安静。 3. ①keep doing sth. 意为"继续干某事"，表示不间断地持续干某事，keep后不能接不定式或表示静止状态的v-ing形式，而必须接延续性的动词。例：He kept working all day, because he wanted to finish the work on time. 他整天都在不停地工作，因为他想准时完成工作。 Keep passing the ball to each other, and you'll be OK.坚持互相传球，你们就

to of和for的区别

to , of 和for的区别 1.to有到的意思，常常和go，come，get连用引出地点。Go to school , go to the shop , go to the cinema. 常见的短语：the way to 去---的路 On one’s way to 在某人去---的路上以上的用法中，当地点是副词home，here，there等是to 要去掉。如：get home，the way here To后跟动词原形，是不定式的标志 It is +形容词+(for/of +人+)to do sth.(括号内部分可以省略) It is easy for me to learn English. It is very kind of you to lend me your money. 当形容词表示人的行为特征时用of表示to do的性质时用for Want, hope ,decide, plan , try , fail等词后跟to do I want to join the swimming club. Would like to do I’d like to play basketball with them. It is time to have a break. Next to , close to , from ---to--- 2.for 为，表示目的。 Thank you for Buy sth for sb =buy sb sth It is time for bed. Here is a letter for you.

I will study for our country. 3.of表示所属关系意思是：---的 a map of the world a friend of mine

for和of引导的不定式结构的区别

for和of引导的不定式结构的区别不定式是一种非谓语动词，不能单独作谓语，因此没有语法上的主语。但由于不定式表示的是动作，在意义上可以有它的主体。我们称之为逻辑主语。提起不定式逻辑主语，人们首先想到的会是“for+名词（宾格代词）+不定式”的复合结构。如：It is important for us to study English well．然而，有时不定式的逻辑主语须要用“of+名词（代词宾格）”才行。例如：It is kind of you to help me．而不能说：It is kind for you to help me．在选择介词“for”还是“of”时，人们往往总是凭感觉而定。有时受习惯影响，多选介词“for”。于是常出现这样的错误：It was careless for him to lose his way．It is cruel for you to do so．由于众多语法书对这种结构中使用“for”与“of”的区别介绍甚少，一些人对其概念认识尚不完全清楚，笔者认为有必要就这一问题作些探讨与介绍。一、在句中的语法作用不同 a．不定式for结构在句中可以作主、宾、表、定、状、同位语： 1．It is easy for Tom to do this work．（主语）汤姆做此工作是容易的。 2．I'd like for him to come here．（宾语）我喜欢他来这里。 3．His idea is for us to travel in two different groups．（表语）他的想法是：我们分成两组旅行。 4．Have you heard about the plan for you to go abroad．（定语）你听到让你出国的计划吗？ 5．The word is too difficult for him to pronounce well．（状语）这单词太难，他念不准。 6．In the most schools，it is the custom for the headmaster to declare the newterm start．在大部分学校，校长宣布新学期开始是一个习惯。 b．不定式of结构只能在句中作主语。 1．It was careless of him to leave his umbrella in the train．他把伞丢在火车上真是太粗心了。 2．It is awfully good of you to come to see me off at the station．谢谢你来车站送我。二、逻辑主语的名词有所不同

of和for的用法

for 表原因、目的 of 表从属关系介词of的用法（1）所有关系 this is a picture of a classroom （2）部分关系 a piece of paper a cup of tea a glass of water a bottle of milk what kind of football，american of soccer？（3）描写关系 a man of thirty 三十岁的人 a man of shanghai 上海人（4）承受动作 the exploitation of man by man．人对人的剥削。（5）同位关系 it was a cold spring morning in the city of london in england．（6）关于，对于 what do you think of chinese food？你觉得中国食品怎么样？介词for 的用法小结 1. 表示“当作、作为”。如: i like some bread and milk for breakfast. 我喜欢把面包和牛奶作为早餐。what will we have for supper? 我们晚餐吃什么? 2. 表示理由或原因,意为“因为、由于”。如: thank you for helping me with my english. 谢谢你帮我学习英语。 thank you for your last letter. 谢谢你上次的来信。 thank you for teaching us so well. 感谢你如此尽心地教我们。 3. 表示动作的对象或接受者,意为“给……”、“对…… (而言)”。如:

介词for和to用法完全归纳

介词for用法完全归纳？本站特约作者陈根花？用法1：(表目的)为了。如： They went out for a walk. 他们出去散步了。 What did you do that for 你干吗这样做？ That’s what we’re here for. 这正是我们来的目的。 What’s she gone for this time 她这次去干什么去了？ He was waiting for the bus. 他在等公共汽车。【用法说明】在通常情况下，英语不用 for doing sth 来表示目的。如：他去那儿看他叔叔。误：He went there for seeing his uncle. 正：He went there to see his uncle. 但是，若一个动名词已名词化，则可与 for 连用表目的。如： He went there for swimming. 他去那儿游泳。(swimming 已名词化) 注意：若不是表目的，而是表原因、用途等，则其后可接动名词。(见下面的有关用法) 用法2：(表利益)为，为了。如： What can I do for you 你想要我什么？ We study hard for our motherland. 我们为祖国努力学习。 Would you please carry this for me 请你替我提这个东西好吗？ Do more exercise for the good of your health. 为了健康你要多运动。【用法说明】(1) 有些后接双宾语的动词(如 buy, choose, cook, fetch, find, get, order, prepare, sing, spare 等)，当双宾语易位时，通常用 for 来引出间接宾语，表示间接宾语为受益者。如： She made her daughter a dress. / She made a dress for her daughter. 她为她女儿做了件连衣裙。 He cooked us some potatoes. / He cooked some potatoes for us. 他为我们煮了些土豆。注意，类似下面这样的句子必须用 for： He bought a new chair for the office. 他为办公室买了张新办公椅。 (2) 注意不要按汉语字面意思，在一些及物动词后误加介词 for：他们决定在电视上为他们的新产品打广告。误：They decided toadvertise for their new product on TV. 正：They decided to advertise their new product on TV. 注：advertise 可用作及物或不及物动词，但含义不同：advertise sth＝为卖出某物而打广告；advertise for sth＝为寻找某物而打广告。如：advertise for a job=登广告求职。由于受汉语“为”的影响，而此处误加了介词 for。类似地，汉语中的“为人民服务”，说成英语是 serve the people，而不是 serve for the people，“为某人的死报仇”，说成英语是avenge sb’s death，而不是 avenge for sb’s death，等等。