Testicular Shielding for Total Body Irradiation in Pediatric Patients: A Single Institution's Approach

Abstract

Total body irradiation (TBI) has been used as a part of the conditioning regimen for patients undergoing hematopoietic stem cell transplantation (HSCT) for certain non-malignant conditions such as sickle cell disease. While effective, TBI can cause lasting side effects for pediatric patients including oligospermia or even permanent azoospermia. Although many investigators have studied testicular shielding during TBI for non-malignant conditions, there is no set standard. The purpose of this study is to describe a different technique to conduct testicular shielding in male pediatric patients undergoing TBI for non-malignant conditions.We describe three patients who underwent TBI as part of their conditioning regimens for allogeneic HSCT. The testicular shielding technique is reported, together with the optically stimulated luminescence dosimeter (OSLD) results for the gonads. For the patients being treated in the upright, sitting position with AP/PA fields, the testicular shielding was placed using the shadow from the field light. For the patient treated in the decubitus position with AP/PA fields, a surface rendering was generated using the treatment planning system which guided the physical placement of the gonadal block. OSLDs were placed in the middle of the scrotal surface, behind the gonadal blocks, for both the AP and PA orientations to verify the delivered dose to the testicles.The OSLD readings for patient 1 indicated a dose of 43 cGy to the gonads for the first TBI course, a 78.5% decrease from the prescribed dose of 200 cGy. For the second TBI course, this patient received a total dose of 63 cGy to the gonads, an 84.3% decrease from the prescribed dose of 400 cGy. The OSLD readings for patient 2 indicated a dose of 31 cGy to the gonads for the first TBI course, an 84.5% decrease from the prescribed dose of 200 cGy. For the second TBI course, patient 2 received a total dose of 75 cGy to the gonads, an 81.3% decrease from the prescribed dose of 400 cGy. The OSLD readings for patient 3 indicated a total dose to the gonads of 29 cGy, an 85.5% decrease from the prescribed dose of 200 cGy.We report here an effective technique to shield the testicles of male pediatric patients undergoing TBI. We verified that our technique reduces the testicular dose by approximately 80- 85% of the TBI prescription dose in three male pediatric patients, keeping the dose well below the documented doses that can cause permanent infertility and hypogonadism.