National Survey of Radiation Dose and Image Quality in Adult CT Head Scans in Taiwan

ESTIMATION OF RADIATION RISK AND ESTABLISHMENT OF DIAGNOSTIC REFERENCE LEVELS FOR PATIENTS UNDERGOING COMPUTED TOMOGRAPHY CHEST-ABDOMEN-PELVIC EXAMINATIONS IN SUDAN

Establishment of diagnostic reference levels (DRLs) is an essential radiation optimization tool used to indicate optimum practice and radiation protection. This study aimed to report the current computed tomography (CT) of the chest-abdomen-pelvis radiation practice in Sudan as a part of the DRL establishment effort and dose optimization. CT radiation doses were collected from 530 patients of age ranging between 28 and 85 y and body weight ranging between 65 and 120 kg. DRLs were calculated based on the 75th percentile of dose length product (DLP) and CT dose index volume (CTDIvol). Effective and organ doses were calculated using the National Cancer Institute dosimetry system for the CT programme. The proposed DRLs are CTDIvol, 6 mGy, and DLP, 970 mGy.cm, and an effective dose of 9.9 mSv. Organ dose estimation showed that the thyroid received the highest dose during the scan.

Computed tomography diagnostic reference levels for adult brain, chest and abdominal examinations: A systematic review

OBJECTIVES

Radiation dose variation within and among Computed Tomography (CT) centres is commonly reported. This work systematically reviewed published articles on adult Diagnostic Reference Levels (DRLs) for the brain, chest and abdomen to determine the causes and extent of variation. A systematic literature search and review was performed in selected databases containing leading journals in radiography, radiology and medical physics using carefully defined search terms related to CT and DRLs. The quality of the included articles was determined using the Effective Public Health Practise Project tool for quantitative studies.

KEY FINDINGS

The 54 articles reviewed include: 45 studies using human data, 8 studies using phantom data, and one study with both human and phantom data. The main comparator in between studies was the dose indices used in reporting DRLs. DRL variations of up to a factor of 2 for the same procedure were noted in phantom studies, and up to a factor of 3 in human studies. Sources of variation include the type of scanner, the age of the scanner, differences in protocols, variations in patients, as well as variations in study design. Different combinations of dose indices were reported: volume computed tomography dose index (CTDIvol) and dose length product (DLP) (59%); DLP only (11%); weighted computed tomography dose index (CTDIw) and DLP (9%); CTDIvol only (7%); CTDIvol, DLP and effective dose (ED) (6%); CTDIw only (4%); CTDIvol, DLP and size specific dose estimate (SSDE) (1%) and CTDIw, CTDIvol and DLP (1%). The use of different dose indices limited dose comparison between studies.

CONCLUSION

The study noted a 2-3 fold variation in DRLs between studies for the same procedure. The causes of variation are reported and include study design, scanner technology and the use of different dose indices.

IMPLICATIONS FOR PRACTICE

There is a need for standardisation of CT DRLs in line with the International Commission on Radiological Protection recommendations to reduce dose variation and facilitate dose comparison.