how to bind two-way radio button in angular 2

Here is my code, In last name i used ngModel so its working two way data binding but in radio button how I used ngModel for two way data binding.

   <div class="form-group" [ngClass]="{ 'has-error': f.submitted && !lastname.valid }">
                    <label for="lastname">Last Name</label>
                    <input type="text" class="form-control" name="last_name" [(ngModel)]="employee.last_name" #lastname="ngModel" required />
                    <div *ngIf="f.submitted && !lastname.valid" class="help-block">Last Name is required</div>
                </div>
                <div class="form-group">
                    <label>Gender:</label> &nbsp;
                    <label class="radio-inline">
                    <input type="radio" name="optradio" [checked]="employee.gender == 'Male'" >Male
                </label>
                    <label class="radio-inline">
                     <input type="radio" name="optradio" [checked]="employee.gender == 'Female'" >Female
                </label>
                </div>