Photographs can be used in therapy in many ways and there is a very good website dedicated to phototherapy which includes articles and examples of the work that photo-therapist’s engage in. https://phototherapy-centre.com/more-information/#history
I have found that using photographs in art therapy groups provides an enjoyable way of sharing ideas related to our choice of photographs and for individuals in the group and also the therapist to introduce themselves to each other in a fun and easy way. Over the years since I was first introduced to the idea of using found imagery in art therapy groups, I have taken many photographs of objects and scenes that represent a diverse collection with images chosen to evoke a feeling response by the person who selects them. The images can be used in many ways that evoke sharing and reflection.