Adrenal Stereotactic Body Radiation Therapy: The Effects of a Full and Empty Stomach on Radiation Dose to Organs at Risk

Abstract

Purpose/Objective(s)Evidence of the effectiveness of Stereotactic Body Radiation Therapy (SBRT) has recently been published [1-11]. It has also been reported that curative treatment for oligometastasis. There is also a form of adrenal recurrence after radical resection of the primary lesion. However, the adrenal glands are surrounded by radiation-sensitive organs, such as the pancreas, kidneys, small intestine, biliary system, and stomach. Treatment planning therefore requires many regulations due to the dose limit to the organ at risk. Radiotherapy can be adjusted for gastric capacity. We therefore performed an OAR analysis for SBRT to the left adrenal gland based on gastric state (empty or full stomach) at the time of irradiation. We examined whether it was possible to reduce the dose to OAR.Materials/MethodsA sample of 20 randomly selected stomachs were arranged in descending order from the largest to the smallest size and divided into two groups of 10. The “empty group” is defined as the smaller stomach group (n = 10), while the “full group” is the larger stomach group (n = 10). Clinical target volume (CTV) adds a 3 mm margin to the GTV. Planning target volume (PTV) is in the same range as CTV. The prescribed PTV dose was 54 Gy / 6 fx and D 95 coverage of PTV(CTV) (the dose to 95% of the PTV volume). The capacity of the stomach was measured for its effects on OAR. We compare the difference between two groups as stomach volume.ResultsThe gastric OAR dose in the empty group was significantly lower than in the full group (D5 and D10). However, the OAR dose to the left kidney in the empty group was statistically significantly higher than in the full group (V12, V15, and V21).ConclusionWhen SBRT was performed on the left adrenal gland, it was found that the smaller the stomach size, the lower the dose to the stomach. The stomach is an abdominal organ that can be artificially resized. Therefore, it is better to perform SBRT on patients with an empty stomach. Evidence of the effectiveness of Stereotactic Body Radiation Therapy (SBRT) has recently been published [1-11]. It has also been reported that curative treatment for oligometastasis. There is also a form of adrenal recurrence after radical resection of the primary lesion. However, the adrenal glands are surrounded by radiation-sensitive organs, such as the pancreas, kidneys, small intestine, biliary system, and stomach. Treatment planning therefore requires many regulations due to the dose limit to the organ at risk. Radiotherapy can be adjusted for gastric capacity. We therefore performed an OAR analysis for SBRT to the left adrenal gland based on gastric state (empty or full stomach) at the time of irradiation. We examined whether it was possible to reduce the dose to OAR. A sample of 20 randomly selected stomachs were arranged in descending order from the largest to the smallest size and divided into two groups of 10. The “empty group” is defined as the smaller stomach group (n = 10), while the “full group” is the larger stomach group (n = 10). Clinical target volume (CTV) adds a 3 mm margin to the GTV. Planning target volume (PTV) is in the same range as CTV. The prescribed PTV dose was 54 Gy / 6 fx and D 95 coverage of PTV(CTV) (the dose to 95% of the PTV volume). The capacity of the stomach was measured for its effects on OAR. We compare the difference between two groups as stomach volume. The gastric OAR dose in the empty group was significantly lower than in the full group (D5 and D10). However, the OAR dose to the left kidney in the empty group was statistically significantly higher than in the full group (V12, V15, and V21). When SBRT was performed on the left adrenal gland, it was found that the smaller the stomach size, the lower the dose to the stomach. The stomach is an abdominal organ that can be artificially resized. Therefore, it is better to perform SBRT on patients with an empty stomach.