Faster RCNN with resnet101 FPN

I trained a pretrained faster RCNN with resnet50 FPN and I would try to do the same thing with a resnet101.

  1. Is there a way to train a pretrained faster RCNN with resnet101 FPN as backbone ?

  2. And ideally to change the anchor boxes sizes (with a pretrained mode on resnet 101 or resnet 50)? Because I know that my objects are supposed to have always the same shape.

Thank you very much

Would this help, for ResNet50?

anchor_sizes = ((32,), (64,), (128,), (256,), (512,)) 
aspect_ratios = ((0.5, 0.75, 1.0),) * len(anchor_sizes) 
anchor_generator = AnchorGenerator(anchor_sizes, aspect_ratios)
# get the number of input features 
in_features = modelr.roi_heads.box_predictor.cls_score.in_features
# define a new head for the detector with required number of classes
modelr.roi_heads.box_predictor = FastRCNNPredictor(in_features, num_classes) 
modelr.rpn.anchor_generator = anchor_generator #adding in customized anchors