CN108711447A - The strong Multipurpose Optimal Method of tune automatically based on voxel weight factor and its application - Google Patents
The strong Multipurpose Optimal Method of tune automatically based on voxel weight factor and its application Download PDFInfo
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Abstract
Due to the multiple target of planning optimization and the non-intellectual of dose constraint, the method for clinical-use human work trial and error adjusts dosage the way of restraint optimal planning repeatedly, there are problems that efficiency of plan is low, quality uncertainty.The present invention discloses a kind of intensity modulated radiation therapy Multipurpose Optimal Method based on voxel weight factor, thoughtcast of the simulation game designer in design, adjust automatically constraint, to guarantee plan quality.This method is ranked up and sorts out to the attention degree of area-of-interest dose constraint according to clinic, forms constraint priority list, then using list as foundation, adjusts dose constraint.When gained solution is unsatisfactory for present confinement, according to priority low height relaxes to violating item successively；When gained solution meets present confinement, according to priority height is tightened (dose constraint for first tightening violation) to items successively, until obtaining last minute planning.The above method is used for cervical cancer patient, as a result shows that the present invention can reduce the workload of plan designer, improvement plan quality.
Description
Technical field
The present invention relates to medical radiotherapy technical field, in particular to the Multipurpose Optimal Method of intensity modulated radiation therapy plan with
And the specific utilization of this method.
Background technology
Intensity modulated radiation therapy (Intensity Modulated Radiation Therapy, IMRT) is that current utilization is most extensive
Treatment mode.Compared with traditional three-dimensional conformal radiotherapy, intensity modulated radiation therapy has many potential advantages, can in target area
It is formed and is distributed with target area conformal degree higher and the better dosage of uniformity, while in target area and normal structure or jeopardizing organ boundaries
Dose degradation is rapid.So as to while not reducing target dose, effectively reduce normal structure or jeopardize being measured for organ, carry
High tumor control rate (Tumor Control Probability, TCP) or (and) reduce Normal Tissue Complication incidence
(Normal Tissue Complication Probability,NTCP)。
The design of intensity modulated radiation therapy Inverse Planning optimizes, and the purpose is to allow tumor locus to be irradiated by enough high doses, kills
While dead or inhibition growth of tumour cell, makes the radioactive dose minimum for jeopardizing organ, normal surrounding tissue, put by force so adjusting
It is substantially a multiple-objection optimization to treat planning optimization.For example, for an example cervical cancer patient, not only need to consider tumor locus
By according to situation, it is also necessary to consider rectum, bladder, femoral head etc. jeopardize organ by according to situation；Jeopardize organ (such as a certain
Rectum), it also needs to consider V respectively30Gy、DmaxEtc. different dose constraints.
But improve tumor locus exposure dose and reduce jeopardize organ, surrounding tissue radioactive dose between often mutually
Contradiction, clinically doctor wish to find a balance therebetween, to reach preferable therapeutic effect.In addition, ideal
Dose constraint have individual specificity, and plan design before be it is unknown, clinically plan designer's common practice be according to
According to the standard value being currently based in the clinical procedure of population statistics, then it is aided with my experience manually trial and error (trial and
Error) method adjusts dose constraint repeatedly, repeatedly optimizes radiotherapy planning, and the plans until obtaining meeting dose requirements are
Only.The method of artificial trial and error not only expends time, energy, but also plan designer is needed to have abundant clinical experience, plan
Quality is usually closely related with the time it takes, energy and experienced degree, it is difficult to the consistency of guarantee plan quality, meter
The efficiency for delineating meter is also low.
It is on the other hand, clinical to carry out the voxel weight factor optimization method based on organ used in radiotherapy planning optimization,
Same organs or the weight of structure organization are identical, limit Pareto (Pareto) plane search model of optimization method
It encloses, the plan for weighing dose constraint very well cannot be obtained.Studies have shown that voxel in the Optimized model based on voxel weight factor
Weight factor it is mutually independent, can significantly extend Pareto (Pareto) plane search range, obtain more excellent tradeoff
Plan.
2007, the A novel approach to that Breedveld et al. is delivered on Phys Med Bio publications
Multi-criteria inverse planning for IMRT, describe a kind of Model for Multi-Objective Optimization, the model is automatic
Dose constraint is adjusted, however the voxel weight factor adjustment model that this method is used is to maintain secrecy, and is not applied to
Cases of cervical cancer.
2013, the Automatic treatment plan that Nan Li et al. people delivers on Phys Med Bio publications
Re-optimization for adaptive radiotherapy describe a kind of method of adjustment of voxel weight factor, should
Method by finding out the part being inferior in present dose volume histogram (DVH, Dose-Volume Histogram) with reference to DVH,
It adjusts its voxel weight factor, however this method of adjustment is suitable for re-optimization scene, be with reference to DVH information before planning optimization is not
Know.
Invention content
For overcome the deficiencies in the prior art, radiotherapy planning quality is ensured, it is an object of the invention to open one kind to be based on
The intensity modulated radiation therapy plan Multipurpose Optimal Method of voxel weight factor, the thoughtcast of simulation game designer automatically adjust
Dose constraint, improvement plan quality.It is another object of the present invention to provide a kind of new tune based on voxel weight factor
Whole strategy and the concrete application that the Multipurpose Optimal Method is provided.
Technical scheme is as follows：
A kind of intensity modulated radiation therapy plan Multipurpose Optimal Method based on voxel weight factor, mainly recirculates including two,
Outer circulation and interior cycle.According to the result adjust automatically dose constraint of optimization, interior cycle is then a kind of based on voxel power for outer circulation
Fluence distribution optimization (FMO, Fluence Map optimization) Optimized model of repeated factor, it is characterised in that including following
Step：
(1) Optimized model of the fluence distribution optimization based on voxel weight factor is established
(1.1) foundation of optimization object function
The target area of acquisition plan and jeopardize organ contours, after launched field arrange parameter and desired amount distributed intelligence, is intended to
The desired dosage distribution shifts of designer are optimization object function as shown in formula 1：
In formula 1, V indicates that the set of voxels of each area-of-interest, v indicate that a certain area-of-interest, H indicate that dosage is heavy
Product matrix is calculated by the unlimited beam of quadrant (QIB, quadrant infinite beam) dose calculation methodology, and f indicates irradiation
Wild intensity distribution, f are vector, and Hf is that the dosage of a certain area-of-interest is distributed, and Hf is one-dimensional matrix；Indicate optimal dosage
Distribution is one-dimensional matrix, and the dosage of target area is prescribed dose, and it is 0 to jeopardize organ；ξvOrgan weight factor is indicated, for vector, member
Plain number is equal with involved area-of-interest,It indicates voxel weight factor, is diagonal matrix, diagonal entry number
It is equal with current interest region voxel number, ()TFor the transposition operation of matrix.The Section 2 of object function is smooth item,
(Mf)T(Mf) be irradiation field intensity distribution second derivative, s is smooth coefficients, by user's predefined, range is 0.001~
1, can be 0.001,0.01,0.1,1.
(1.2) selection of voxel weight factor adjusting range
When optimum results are unsatisfactory for dose constraint condition, the power of the voxel of dose constraint condition is often unsatisfactory for by increase
Repeated factor repeatedly optimizes, to obtain the plan for meeting dose constraint condition.The dose constraint that this method is related to is clinically
Most common dose constraint (maximum, minimum dose constraint) and dose volume constraint (including maximum, minimum dose volume constraint).
For maximum dose constraint, if target area (PTV, Planning Target Volume) or jeopardize organ (OAR,
Organ at risk) dose volume histogram (DVH, Dose Volume Histogram) in there are dose value be more than Dc
The voxel of (threshold dose) then increases acceptable dose and is more than DcVoxel weight factor；For minimum dose constraint, if currently
There are dose values to be less than D in the DVH of PTVcVoxel, then increase accepting agent magnitude and be located at;D100%, Dc]Voxel weight factor
(D100%For the minimizing agent magnitude of current PTV).
For maximum dose volume constraint, when the dose constraint of a certain PTV or OAR isI.e. acceptable dose is more than
Dose value DcVolume be less than equal to Vc, and acceptable dose is more than or equal to the volume of dose value D in the DVH of current PTV or OAR
For Vc(D > Dc), that is, correspond to volume VcDose value be D, since the voxel middle dosage value of violation is close to DcVoxel apart from target
Area is farther, and dose value is easier to reduce, and increased dosage amount value is in Qu Jian [ at this time;Dc, D]Voxel weight factor.It is similar
Ground, for minimum dose volume constraint, when the dose constraint of PTV isI.e. acceptable dose is more than dose value DcVolume
It is greater than and is equal to Vc, and volume of the acceptable dose more than or equal to dose value D is D in the DVH of current PTVc(D < Dc), increase at this time
Dosage is in Qu Jian [D, Dc]Voxel weight factor.
(1.3) adjustable strategies of voxel weight factor
Need adjust voxel determine after, the minimum dose constraint for PTV and minimum dose volume constraint, voxel weight because
Son adjustable strategies beFor maximum dose constraint and maximum dose volume constraintThe adjustable strategies of voxel weight factor areWhereinWithIt is respectively
The weight factor of kth+1 and kth time iteration voxel j；DcFor threshold dose；The dose value of kth time iteration voxel j；Coefficient μ, α
> 0 is defined by the user, related to optimal speed, plan quality.The definition of μ, α first can be consolidated α by control variate method
It is fixed, increase μ at certain intervals between range 1~30, reduces until object function converges to the corresponding iterations of minimum value
It amplitude very little or cannot solve；Then μ is fixed, increases α at certain intervals between range 0.001~1, until object function
The corresponding iterations of minimum value are converged to reduce amplitude very little or cannot solve.Simultaneously because with parameter alpha, the increase of μ,
Optimization Solution search space reduces.The selection of parameter needs under the premise of ensureing that convergence rate ensures, to obtain more good meter
It draws.
(2) foundation of Model for Multi-Objective Optimization
This multiple-objection optimization flow generates about the attention degree of Different Organs dose constraint item firstly the need of according to clinic
Beam priority list is foundation by the list, and it is reasonable to be carried out to all bound term on the basis of current planning optimum results
Relaxation or tension, until all bound term cannot be tightened up.
Key step includes：
(2.1) generation of constraint priority list
The list element of constraint priority list is made of area-of-interest bound term of interest, and area-of-interest is about
Beam item includes dose constraint and dose-volume constraint.Since the purpose of radiotherapy is allowed and jeopardizes while the high-dose irradiation of target area
Organ low dose exposure as far as possible.In conjunction with radiotherapy related specifications (the International evaluation of of cervical cancer patient
Radiotherapy technology effectiveness in cervical cancer) it is tensed by the way of rounding
The dose constraint of PTV, by the D of area-of-interest PTV99%,D97%,V49,DmaxWith the D of bodymaxIt is set as hard constraint.While in order to
Ensure to ensure the conformal degree that dosage is distributed, introduce area-of-interest " body-(target area extends out 1 centimetre) " and limits its maximum
Dosage.
For soft-constraint, the radiation sensitivity of organ is jeopardized according to difference first, rear difference jeopardizes organ and radiates
Difference is jeopardized organ classification by reaction severity.Radioreaction occurs than low dose exposure due to generally receiving high-dose irradiation
Probability it is big, dose constraint item is ranked up by acceptable dose is high to Low then, obtains a clinical attention degree from high to low
Constraint priority list.Such as radiotherapy patients with cervix carcinoma plan, jeopardize the attention degree of organ from rectum, bladder,
Intestines, femoral head, bone decline successively, and the radioreaction of wherein rectum and bladder is most fierce.
Constraint priority list includes three row, and first is classified as area-of-interest, and second is classified as dose constraint or dose-volume
Constraint, third are classified as priority, and the method for determination of priority is that the constraint priority list that will be sorted and sort out will be similar
Dose constraint item is divided into same grade, and as clinical attention degree declines, priority is lower.
Area-of-interest bound term is divided into hard constraint and soft-constraint, and hard constraint is the constraint that cannot be violated, in optimization process
In the constraint that will not be relaxed and tense, including target area lowest dose level constraint and target area or part jeopardize the maximum agent of organ
Amount constraint；Soft-constraint is the bound term for being relaxed or tightening in optimization process, may also be upgraded with the progress of optimization process
At hard constraint, main includes maximum dose constraint and the dose volume constraint that organ is jeopardized in part.
The constraint priority list of cervical cancer patient is as shown in table 1, wherein different digital indicates different grades of in the 3rd row
Constraint, the smaller expression constraint priority of number are higher；Number 0 is corresponding to be constrained to hard constraint, remaining is soft-constraint.
1. prescribed dose of table is the constraint priority list of the cervical cancer patient of 4500cGy
(2.2) adjustment of dose constraint item
The adjustment of dose constraint item can be divided into 4 steps,
I) setting initial p TV, OAR voxel weight factor, optimal dosage distribution and predose constraints, then into
The FMO optimizations based on voxel weight factor that row maximum iteration is N1, obtain predose distribution；If the first step cannot
The predose distribution for meeting all dose constraints is obtained, into second step, is otherwise directly entered the 4th step
Ii all soft-constraints of lowest priority, pine) are in the dose constraint that according to priority low high sequence relaxation violates
Relaxation method is to increase by 0.5% to the value of present confinement item；It is excellent that the FMO that maximum iteration is N2 is all carried out after relaxing each time
Change, until obtaining meeting the plan of present dose constraints；
Iii) by priority sequence tense successively i-th i) violate in step result predose constraints it is soft about
Beam, the method for tension are to reduce 0.5% to the value that present dose constrains；Until the soft-constraint of tension meets corresponding initial target
It is worth or reaches maximum iteration N3, until the soft-constraint currently tensed is upgraded into hard constraint；
Iv) remaining soft-constraint is tensed successively from high to low according to priority, if cannot expire after reaching maximum iteration N4
Sufficient present dose constraints, by the soft-constraint currently tensed upgrading at hard constraint, the method for tension is to constrain present dose
Value reduce 0.5%, until soft-constraint is not present, obtain final plan at this time.
The main purpose of the first step is to obtain constraining in predose with the FMO optimization methods based on voxel weight factor
Under the conditions of predose distribution, mainly comprise the following steps setting initial p TV, OAR voxel weight factor, optimal dosage distribution and just
Then the parameters such as beginning dose constraint condition carry out the FMO optimizations based on voxel weight factor that maximum iteration is N1, obtain
Predose is distributed.If the first step cannot obtain the predose distribution for meeting all dose constraints, into second step, otherwise
It is directly entered the 4th step.It is all in lowest priority in the dose constraint that the according to priority low high sequence relaxation of second step violates
Soft-constraint, relaxation method are to increase by 0.5% to the value of present confinement item, such as the current dose constraint entry value is 43.81%, then
Dose constraint entry value after relaxation is 44.31%.It all carries out the FMO that maximum iteration is N2 after relaxing each time to optimize, directly
Until the plan for obtaining meeting present dose constraints.Due to obtain at this time there may be loose dosage in the works about
Next beam will tense dose constraint.Third step is tensed in second step result one by one successively by priority sequence to be disobeyed
The soft-constraint of anti-predose constraints, until the soft-constraint of tension meets corresponding initial target value or reaches greatest iteration
Times N 3, until the soft-constraint currently tensed is upgraded into hard constraint.4th step according to priority from high to low according to next one
The remaining soft-constraint of a tension, if present dose constraints cannot be met after reaching maximum iteration N4, by what is currently tensed
Soft-constraint upgrades into hard constraint, until soft-constraint is not present, obtains final plan at this time.Similarly, dosage is tensed about
The mode of beam is to reduce 0.5% to the value that present dose constrains.
The operation principle of this Multipurpose Optimal Method is, from the point of view of the flow of clinical IMRT plan designs, plan design
Be between the process optimized there are certain contact, key guidance information therein be last planning optimization as a result,
The method of automatic multiple-objection optimization can be by the thoughtcast of simulation game designer, according to last optimization as a result,
As a result, adjust automatically dose constraint, to the quality for the plan of improving.On the other hand, use based on voxel weight factor
FMO Optimized models are also beneficial to improvement plan quality.
The method of the present invention is the optimization to radiotherapy planning quality, and does not lie in and carry out radiotherapy to lived subject
Treatment, optimization method of the invention can be used for clinic, can be used for non-diagnostic and therapeutic purposes research purposes.
Compared with prior art, the present invention haing the following advantages and advantageous effect：
(1) energy adjust automatically dose constraint reduces dependence of the plan design to plan designer, the quality of guarantee plan.
(2) Optimized model based on voxel weight factor is used, preferably target area high-dose irradiation is weighed and protection jeopardizes
Contradiction between organ.
(3) simulation game designer carries out the thoughtcast of plan design, and workflow is simple, understandable, it is easier to be counted
Designer is drawn to receive.
Description of the drawings
Fig. 1 is the multiple-objection optimization the general frame based on voxel weight factor.
Fig. 2 is the adjusting range schematic diagram of voxel weight factor.
Fig. 3 is that dose constraint item adjusts flow chart.
Fig. 4 is the comparison diagram of original (clinic) DVH and optimization DVH of 10 cervical cancer patients.
Fig. 5 is original (clinic) the hard constraint entry value and optimization hard constraint entry value comparison diagram of 10 cervical cancer patients.
Fig. 6 is original (clinic) the soft-constraint entry value and optimization soft-constraint entry value comparison diagram of 10 cervical cancer patients.
Specific implementation mode
The method of the present invention is described in further detail with reference to embodiment, but the applicable tumor type of the present invention
It is not limited thereto, without departing from the idea case in the present invention described above, according to ordinary skill knowledge and strong hand
Section, makes various replacements and change, should all include within the present invention.
Embodiment 1
A kind of IMRT Multipurpose Optimal Methods based on voxel weight factor, include the following steps：
(1) foundation of the FMO Optimized models based on voxel weight factor
(1.1) foundation of optimization object function
When the target area of cervical cancer patient and after jeopardize organ and be precisely determined, with by Washington, DC university exploitation and public
Software package radiotherapy research computing environment (CERR, Computational Environment for Radiotherapy opened
Research) as intensity modulated radiation therapy Inverse Planning design platform, launched field parameter, dose calculation engine and area-of-interest are set
Parameter information.For cervical cancer patient, 7 open countries (150 are used0,1000,500,00,3100,2600,2100) adjust intense irradiation, ray
Energy is 6MV, prescribed dose 4500cGy, the area-of-interest being related to have target area, rectum, bladder, intestines, femoral head, bone,
Body-(+1 centimetre of target area), body use intensity modulated radiation therapy plan design platform (IMRTP, the Intensity- of CERR
Modulated Radiation Therapy Planning) in QIB dose calculation engines, generate dosage deposition matrix H.Then
It is following optimization object function to be intended to the desired dosage distribution shifts of designer：
In formula, V indicates that the set of voxels of each area-of-interest, v indicate that a certain area-of-interest, H indicate dosage deposition
Matrix is obtained by dose calculation methodology calculated in advance, and f indicates irradiation field intensity distribution, is a vector, then Hf is that a certain sense is emerging
The dosage in interesting region is distributed, and is an one-dimensional matrix.Indicate optimal dosage distribution and an one-dimensional matrix, certainly by user
Definition.ξvIt indicates organ weight factor, is a vector, element number is equal with involved area-of-interest.Corresponding to sense
Interest region target area, rectum, bladder, intestines, femoral head, bone, body-(+1 centimetre of target area), body, organ weight factor difference
It is 100,1,2,0.1,0.1,0.1,0.1,0.01.It indicates voxel weight factor, is a diagonal matrix, diagonal entry
Number is equal with current interest region voxel number, and initial voxel weight factor is all 1.(·)TIt is transported for the transposition of matrix
It calculates.The Section 2 of object function is smooth item, (Mf)T(Mf) it is the second derivative of irradiation field intensity distribution, s is smooth coefficients,
It is 0.01 by predefined.The iterations N1 of the FMO optimizations based on voxel weight factor in multiple-objection optimization each stage,
N2, N3, N4 are 30,1,30,30 respectively.
(1.2) selection of voxel weight factor adjusting range
When optimum results are unsatisfactory for dose constraint condition, the power of the voxel of dose constraint condition is often unsatisfactory for by increase
Repeated factor optimizes to obtain meeting the plan of dose constraint condition.The dose constraint that this method is related to is clinically the most frequently used
Dosage and dose volume constrain.For maximum dose constraint, if there are dose values to be more than in the DVH curves of current PTV or OAR
DcThe voxel of (threshold dose) then increases acceptable dose and is more than DcVoxel weight factor；For minimum dose constraint, if working as
There are dose values to be less than D in the DVH curves of preceding PTVcThe voxel of (threshold dose) then increases accepting agent magnitude and is located at;D100%, Dc]
Voxel weight factor (D100%For the minimizing agent magnitude of current PTV).For maximum dose volume constraint, as a certain PTV or
The dose constraint of OAR isI.e. acceptable dose is more than dose value DcVolume be less than equal to Vc, and current PTV or
Volume of the acceptable dose more than or equal to dose value D is V in the DVH curves of OARc(D > Dc), that is, correspond to volume VcDose value
For D, since the voxel middle dosage value of violation is close to DcVoxel it is farther apart from target area, dose value be easier reduce, increase at this time
Large dosage value is in Qu Jian [Dc, D]Voxel weight factor.Similarly, for minimum dose volume constraint, when the agent of PTV
Amount is constrained toI.e. acceptable dose is more than dose value DcVolume be greater than equal to Vc, and in the DVH curves of current PTV
Volume of the acceptable dose more than or equal to dose value D is Vc(D < Dc), increased dosage amount is in Qu Jian [ at this time;D, Dc]Voxel power
Repeated factor.
(1.3) adjustable strategies of voxel weight factor
Need adjust voxel determine after, the minimum dose constraint for PTV and minimum dose volume constraint, voxel weight because
Son adjustable strategies beFor maximum dose constraint and maximum dose volume constraintThe adjustable strategies of voxel weight factor areWhereinWithIt is respectively
The weight factor of k+1 and kth time iteration voxel j；DcFor threshold dose；The dose value of kth time iteration voxel j；Parameter μ, α
It is set as 20 and 0.5 respectively.The predose constraints of cervical cancer patient as an example of table 2.
2. prescribed dose of table is the initial constraint priority list of the cervical cancer patient of 4500cGy
(2.2) adjustment of dose constraint item
The adjustment of dose constraint item can be divided into 4 steps, and the main purpose of the first step is to use the FMO based on voxel weight factor
Optimization method obtains the distribution of the predose under predose constraints, mainly comprises the following steps the body of setting initial p TV, OAR
The parameters such as plain weight factor, optimal dosage distribution and predose constraints, then carry out the base that maximum iteration is N1
Optimize in the FMO of voxel weight factor, obtains predose distribution.If the first step cannot obtain meeting all dose constraints
Predose is distributed, and into second step, is otherwise directly entered the 4th step.The agent that the according to priority low high sequence relaxation of second step violates
All soft-constraints of lowest priority are in amount constraint, relaxation method is the value increase by 0.5% to present confinement item, such as when
The preceding dose constraint entry value is 43.81%, then the dose constraint entry value after relaxing is 44.31%.It is all carried out after relaxing each time
The FMO that maximum iteration is N2 optimizes, until obtaining meeting the plan of present dose constraints.Due to obtaining at this time
There may be loose dose constraints in the works, next will tense dose constraint.Third step by priority sequence according to
Next tenses the soft-constraint that predose constraints is violated in second step result, until the soft-constraint satisfaction pair of tension
The initial target value answered reaches maximum iteration N3, until the soft-constraint currently tensed is upgraded into hard constraint.4th step
Remaining soft-constraint is tensed one by one successively from high to low according to priority, is worked as if cannot meet after reaching maximum iteration N4
The soft-constraint currently tensed is upgraded into hard constraint, until soft-constraint is not present, is obtained at this time most by predose constraints
Whole plan.Similarly, the mode for tensing dose constraint is to reduce 0.5% to the value that present dose constrains.
With the Multipurpose Optimal Method based on voxel weight factor, 10 cervical cancer patient plans are optimized,
The dose requirements middle dosage constraint entry value comparing result of wherein an example cervical cancer patient is as shown in table 3.It will
The T that the data of 10 cervical cancer patient dose constraint items are matched two-by-two is examined, and the results are shown in Table 4.
The dose constraint concrete numerical value comparing result of 3. an example cervical cancer patient of table
4. dose constraint point paired-samples T-test result of table
Although an embodiment of the present invention has been shown and described, it will be understood by those skilled in the art that：Not
These embodiments can be carried out a variety of change, modification, replacement and modification by being detached under the principle of the present invention and objective, of the invention
Range claim and its equivalent unlimited.
Claims (7)
1. a kind of intensity modulated radiation therapy plan Multipurpose Optimal Method based on voxel weight factor, including two recirculate, outer circulation and
Interior cycle.According to the result adjust automatically dose constraint of optimization, interior cycle is then a kind of based on voxel weight factor for outer circulation
Fluence distribution optimization (FMO, Fluence Map optimization) Optimized model, which is characterized in that include the following steps：
(1) Optimized model of the fluence distribution optimization based on voxel weight factor is established；
(2) foundation of Model for Multi-Objective Optimization.
2. a kind of intensity modulated radiation therapy plan Multipurpose Optimal Method based on voxel weight factor according to claim 1,
It is characterized in that, in the step (1), the foundation of the Optimized model of the fluence distribution optimization based on voxel weight factor specifically includes
Following steps：
(1.1) foundation of optimization object function
The target area of acquisition plan and jeopardize organ contours, after launched field arrange parameter and desired amount distributed intelligence, is intended to design
The desired dosage distribution shifts of person are optimization object function as shown in formula 1：
In formula, V indicates that the set of voxels of each area-of-interest, v indicate that a certain area-of-interest, H indicate dosage deposition matrix,
It is calculated by pencil beam dose calculation methodology, f indicates irradiation field intensity distribution, is a vector, then Hf is a certain interested
The dosage in region is distributed, and is an one-dimensional matrix,Indicate optimal dosage distribution and an one-dimensional matrix, the dosage of target area
For prescribed dose, it is 0 to jeopardize organ；ξvIndicate organ weight factor, be a vector, element number with it is involved interested
Region is equal,It indicates voxel weight factor, is a diagonal matrix, diagonal entry number and current interest region body
Plain number is equal, ()TSection 2 for the transposition operation of matrix, object function is smooth item, (Mf)T(Mf) it is that irradiation field is strong
The second derivative of distribution is spent, s is smooth coefficients, by user's predefined, ranging from 0.001~1；
(1.2) selection of voxel weight factor adjusting range；
(1.3) adjustable strategies of voxel weight factor.
3. a kind of intensity modulated radiation therapy plan Multipurpose Optimal Method based on voxel weight factor according to claim 2,
It is characterized in that, in the step (1.2), voxel weight factor adjusting range selects, and specific implementation method is：
(1.2.1) for maximum dose constraint, if target area (PTV, Planning Target Volume) or jeopardize organ (OAR,
Organ at risk) dose volume histogram (DVH, Dose Volume Histogram) in there are dose value be more than Dc
The voxel of (threshold dose) then increases acceptable dose and is more than DcVoxel weight factor；
(1.2.2) is for minimum dose constraint, if there are dose values to be less than D in the DVH curves of current PTVcThe body of (threshold dose)
Element then increases accepting agent magnitude and is located at;D100%, Dc]Voxel weight factor (D100%For the minimizing agent magnitude of current PTV)；
(1.2.3) for maximum dose volume constraint, when the dose constraint of PTV or OAR areI.e. acceptable dose is more than
Dose value DcVolume be less than equal to Vc, and acceptable dose is more than or equal to dose value D's in the DVH curves of current PTV or OAR
Volume is Vc(D > Dc), that is, correspond to volume VcDose value be D, since the voxel middle dosage value of violation is close to DcVoxel away from
Off-target area is farther, and dose value is easier to reduce, and increased dosage amount value is in Qu Jian [Dc, D]Voxel weight factor；
(1.2.4) for minimum dose volume constraint, when the dose constraint of PTV isI.e. acceptable dose is more than dose value
DcVolume be greater than equal to Vc, and volume of the acceptable dose more than or equal to dose value D is V in the DVH curves of current PTVc(D <
Dc), increased dosage amount is in Qu Jian [ at this time;D, Dc]Voxel weight factor.
4. a kind of intensity modulated radiation therapy plan Multipurpose Optimal Method based on voxel weight factor according to claim 2,
It is characterized in that, in the step (1.3), the adjustable strategies of voxel weight factor, specific implementation method is：
(1.3.1) is usedWithThe weight factor of kth+1 and kth time iteration voxel j is indicated respectively；DcIndicate critical dose
Amount；Indicate the dose value of kth time iteration voxel j；Coefficient μ, α > 0 is defined by the user, with optimal speed, plan quality
It is related；The definition of μ, α first can be fixed α by control variate method, increase μ at certain intervals between range 1~30, directly
The corresponding iterations reduction amplitude very little of minimum value is converged to object function or cannot be solved；Then μ is fixed, in range
Increase α between 0.001~1 at certain intervals, reduces amplitude very until object function converges to the corresponding iterations of minimum value
It is small or cannot solve.Simultaneously because with parameter alpha, the increase of μ, Optimization Solution search space reduces；User needs restraining
Tradeoff is to determine parameter between speed and plan quality；
(1.3.2) for the minimum dose constraint and minimum dose volume constraint of PTV, the adjustable strategies of voxel weight factor are
(1.3.3) is for maximum dose constraint and maximum dose volume constraintThe adjustable strategies of voxel weight factor are
5. a kind of intensity modulated radiation therapy plan Multipurpose Optimal Method based on voxel weight factor according to claim 1,
It is characterized in that, in the step (2), the foundation of Model for Multi-Objective Optimization specifically includes following steps：
(2.1) generation of constraint priority list；
(2.2) adjustment of dose constraint item.
6. a kind of intensity modulated radiation therapy plan Multipurpose Optimal Method based on voxel weight factor according to claim 1,
It is characterized in that, in the step (2.1), the generation method of constraint priority list is as follows：
(2.1.1) meets clinical requirement in order to ensure planned outcome, and bound term is classified, and is divided into hard constraint and soft-constraint, firmly about
Beam refers to the constraint that cannot be violated, in optimization process will not, the constraint for being relaxed and tensing, include target area lowest dose level constraint
And the maximum dose constraint of organ is jeopardized in target area or part；The hard constraint, soft-constraint refer to being relaxed in optimization process
Or the bound term of tightening, including partly jeopardize maximum dose constraint and the dose volume constraint of organ；
(2.1.2) tenses the dose constraint of PTV by the way of rounding, by the D of area-of-interest PTV99%,D97%,V49,DmaxWith
The D of bodymaxIt is set as hard constraint；Simultaneously in order to ensure to ensure the conformal degree that dosage is distributed, area-of-interest " body-is introduced
(target area extends out 1 centimetre) " and limit its maximum dose；
(2.1.3) jeopardizes organ according to the different radiation sensitivities for jeopardizing organ, rear difference first and puts for soft-constraint
Reaction severity is penetrated to be classified the different dose constraint items for jeopardizing organ by organ；Then again due to generally receiving high agent
The probability that radioreaction occurs than low dose exposure for amount irradiation is big, sorts respectively from high to low by acceptable dose, then in conjunction with danger
And organ classification results and it is each jeopardize the ranking results that organ acceptable dose size obtains dose constraint item be ranked up,
Obtain the constraint priority list of a clinical attention degree from high to low；
(2.1.4) constraint priority list includes three row, and first is classified as area-of-interest, and second is classified as dose constraint or dosage-
Volume constraint, third are classified as priority, and the method for determination of priority is that will sort will be same with the constraint priority list sorted out
The dose constraint item of class is divided into same grade, and as clinical attention degree declines, priority is lower；Highest level is firmly about
Beam, remaining is soft-constraint.
7. a kind of intensity modulated radiation therapy plan Multipurpose Optimal Method based on voxel weight factor according to claim 1,
It is characterized in that, in the step (2.2), the method for adjustment of dose constraint item is largely divided into 4 steps, is as follows：
The step of (2.2.1) first step, the voxel weight factor of initial p TV, OAR, optimal dosage is distributed and predose to be arranged
Then the parameters such as constraints carry out the FMO optimizations based on voxel weight factor that maximum iteration is N1, obtain initial agent
Amount distribution；
(2.2.2) is if the first step cannot obtain the predose distribution for meeting all dose constraints, into second step, otherwise directly
It taps into the 4th step；It is all soft in lowest priority in the dose constraint that the according to priority low high sequence relaxation of second step violates
Constraint, relaxation method are to increase by 0.5% to the value of present confinement item；It is N2's that maximum iteration is all carried out after relaxing each time
FMO optimizes, until obtaining meeting the plan of present dose constraints；Due to obtain at this time there may be width in the works
The dose constraint of pine, will then tense dose constraint；
(2.2.3) third step is tensed in second step result by priority sequence and violates predose constraint one by one successively
The soft-constraint of condition will be current until the soft-constraint of tension meets corresponding initial target value or reaches maximum iteration N3
Until the soft-constraint of tension upgrades into hard constraint；
(2.2.4) the 4th step tenses remaining soft-constraint one by one successively from high to low according to priority, if reaching greatest iteration
Present dose constraints cannot be met after times N 4, the soft-constraint currently tensed is upgraded into hard constraint, it is soft until being not present
Until constraint, final plan is obtained at this time.
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