Breast Displacement and CT Radiation Dose

Study Overview
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Brief Summary
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The primary hypothesis of this study is that breast displacement out of the direct plane of imaging during computed tomography (CT) of the abdomen will reduce effective radiation dose to the female breast. Secondary hypotheses are that image noise and artifacts will also be decreased.

Detailed Description
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Computed tomography (CT) is a significant source of medical-related radiation, and radiation-related cancer risk is increasingly recognized in the medical and lay community. One of the groups at greatest risk for radiation-induced malignancies is young females due to the radiosensitivity of female breast tissue. Breast tissue frequently lies within the imaging plane for CT of the abdomen with limited gain in diagnostic information. We propose displacing this breast tissue out of the direct imaging plane will decrease unnecessary radiation exposure and may also indirectly improve image quality. A device called Chrysalis has been designed and received FDA approval for the purposes of displacing female breast tissue during CT.

Official Title
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Effect of Displacement During Computed Tomography on Breast Radiation Dose and Image Quality

Conditions
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Computed Tomography, Radiation Dosage

Intervention / Treatment
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* Device: Chrysalis breast displacement device


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: scheduled for CT of the abdomen and pelvis at Harborview Medical Center able to provide written informed consent Exclusion Criteria: Inability to provide written consent for self (minor, intubated, sedated, mentally incapacitated, in excessive physical distress) Chest or breast surgery within the previous 8 weeks Breast implants Open wounds to the chest wall Fractures of the ribs or spine within the previous 3 months Patients requiring oxygen therapy Mastectomy Breast radiation therapy Scarring to the breasts which would prevent displacement Claustrophobia is not an absolute exclusion criterion, but patient comfort will be a primary concern.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Standard CT<br>Women assigned to undergo CT using the standard dose reduction methods (including bismuth shielding and tube current modulation) but without the Chrysalis device. | |
| Experimental: Chrysalis CT<br>Women assigned to undergo CT using the standard dose reduction methods (including bismuth shielding and tube current modulation) plus application of the Chrysalis device for breast displacement. | Device: Chrysalis breast displacement device<br>* Chrysalis is a cloth device secured with velcro and buckles around the upper abdomen and chest following manual cephalad breast displacement.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Skin Entrance Radiation Dose During Computed Tomography (CT) | Skin entrance radiation doses will be measured with Thermoluminescent dosimeters (TLDs) affixed to the subject's chest and breast during CT of the abdomen. TLD #1 is at the inframammary fold, serving as internal control for each subject. Three additional TLDs (#2-4) are affixed to the subject's breast at 3 pre-ascribed locations. The same is done for the right and left breasts (8 TLDs total). TLDs will then be submitted to Landaeur for measurement. | from time potential subject approached about possible enrollment to time device and TLDs were removed, on average 1 hour | 
| Relative Skin Entrance Radiation Dose in % During Computed Tomography (CT) | Relative skin entrance dose at the breast (group mean of patient's average skin entrance dose at TLDs 2-4) divided by skin entrance dose at the inframammary TLD (TLD 1) in %. For each patient, doses at TLDs 2-4 were averaged, and then the group mean of this was divided by the group mean at the inframammary TLD, then multiplied by 100 to get % dose. A relative dose of 20% means that the skin entrance dose at the breast was 20% of the skin entrance dose at the inframammary fold. | from time potential subject approached about possible enrollment to time device and TLDs were removed, on average 1 hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| CT Image Noise | To evaluate image noise, mean of the Standard deviation (SD) of the pixel values, measured in Hounsfield units (HU), will be measured in Picture Archiving and Communication System (PACS) using a region of interest (ROI) measuring 90-110 mm^2 in size drawn over each of these body regions: hepatic dome, spleen, renal cortex, retroperitoneal fat, subcutaneous fat, paraspinal muscles, and if present, breast tissue, avoiding vascular structures in each case. SD for ROI measuring 90-110 mm^2 in size will also be drawn over the aorta and inferior vena cava (IVC), remote from contrast mixing artifact, and over medullary bone of the spine. HU is the linear scale by which digital image data are displayed in PACS and reflect relative attenuation compared to distilled water at a standard temperature and pressure (STP) (defined as 0 HU) and of pure air at STP (defined as -1000HU). Within a drawn ROI, the PACS will give the mean attenuation (in HU) and the standard deviation of HU (reflecting | two months | 
| Number of Participants With Presence of Artifacts Based on CT Image Quality | CT images acquired will be reviewed for the presence of artifacts that might be attributed to the displacement device or to the presence of the breast tissue. To evaluate for artifacts, the exam will be qualitatively reviewed by a board certified radiologist for imaging artifacts, such as streak artifact. It will be noted on a per participant basis whether any imaging artifacts are identified. | two months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Computed tomography, Radiation dose, Dose reduction, Breast displacement, Chrysalis device, Image quality