A Pilot Study Evaluating the Effect of 2D Antiscatter Grids on CBCT Image Quality

Inclusion Criteria:

1. Provision to sign and date the consent form.

2. Stated willingness to comply with all study procedures and be available for theduration of the study.

3. Be a male or female aged 18-100.

4. Participants who will be treated or are currently being treated with CBCT-guidedphoton therapy for prostate or prostate-bed, abdomen head and neck, or pelviccancers, or with image-guided proton therapy for prostate or prostate bed cancer.

Exclusion Criteria:

1. Metallic implants in the CBCT scan volume, such as hip prostheses or spinestabilization hardware. Patients with pacemakers, defibrillators, or other implantedelectronic devices. Dental implants, fillings, or fiducial markers may beacceptable, and the decision for inclusion/exclusion will be on a case-by-casebasis, by reviewing prior CT images of the study candidate. Patient's prior CTimages will be reviewed by the PI or the site PI.

2. Patients who do not have the ability to lie still for the duration of his/her CBCTimaging and treatment should be excluded. If image artifacts in prior scans aredeemed excessive, the patient will be excluded from the study.

3. Known pregnancy. (Per SOC, a pregnancy test will be performed prior to CBCT scan onDay 1. At this time, women of child-bearing potential (WOCBP) will receive apregnancy test to re-confirm eligibility).

• Women of child-bearing potential are described as:

1. Age 55 or younger who have not had a negative pregnancy test within 3days. This excludes patients who have had tubal ligation or are alreadypost-menopausal.