A comparison of radiation dose in examination of the abdomen using different radiological imaging techniques

Abstract

Typical radiation doses for abdominal examinations were determined for field sizes and entrance doses commonly selected on image intensifier based digital radiographic systems. In addition, measurements were also performed using conventional film-screen methods, a 100 mm camera combination and a phosphor storage computed radiography system. Both antero-posterior and postero-anterior projections were assessed. An anthropomorphic phantom loaded with lithium fluoride thermoluminescent dosimeters was used to measure entrance surface doses. Organ equivalent doses, deduced using normalized organ dose data, were used to calculate effective dose and effective dose equivalent. A comparison of the imaging techniques on the basis of effective dose indicated that significant dose reductions (by approximately a factor of 3) may be expected if the abdomen is imaged using a postero-anterior rather than an antero-posterior projection for a given imaging system. If digital imaging systems are used instead of a conventional film-screen technique, patient effective dose for a given projection can be lower by at least a factor of 5.

Lumbar spine radiology: analysis of the posteroanterior projection

“…This finding is in general agreement with previous workers where PA projections significantly reduced the dose level for abdominal examinations [10,11]. It must be acknowledged, however, that in previous studies effective dose was calculated, but this was not possible here due to the non-availability of conversion coefficients for the PA lumbar spine.…”

“…The dosemeter was placed in the midline, midway between the anterior and posterior surface representing a position occupied by the small intestine. The 38.9 % dose reduction recorded, coupled with the fact that the small bowel (along with numerous other radiosensitive organs [10]) is closer to the anterior than posterior surface, suggests significant advantages for this highly radiosensitive organ (and others) when the subject is positioned for a PA instead of an AP projection. The internal dose reduction, as well as the docu- Visually sharp reproduction of the intervertebral joints 3…”

“….. the gonad dose may be somewhat reduced particularly in the female ± if a PA projection is obtained in preference to an AP viewº [9]. Marshall, specifically relating to Xrays involving the abdominal region, stated that ªAP projections give rise to higher effective doses than do PA projections because the majority of irradiated radiosensitive organs within the abdomen lie closer to the entrance surface for the AP views in comparison to the PA viewsº [10]. Such statements have been supported by recent research in which Marshall et al [10] and Nic an Ghearr and Brennan [11] demonstrated reductions in effective dose for female patients of 63 and 56 %, respectively when the PA technique was employed.…”

“…Marshall, specifically relating to Xrays involving the abdominal region, stated that ªAP projections give rise to higher effective doses than do PA projections because the majority of irradiated radiosensitive organs within the abdomen lie closer to the entrance surface for the AP views in comparison to the PA viewsº [10]. Such statements have been supported by recent research in which Marshall et al [10] and Nic an Ghearr and Brennan [11] demonstrated reductions in effective dose for female patients of 63 and 56 %, respectively when the PA technique was employed.The PA technique offers numerous advantages compared with other methods of dose reduction. It involves no additional cost which is often a limiting factor for the employment of other, cost-effective dose-reducing methods such as erbium filtration [12,13,14,15] and carbon fibre materials [16,17, 18,19].…”

Should Plain Films of the Lumbar Spine be Taken in the Posterior-to-Anterior or Anterior-to-Posterior Position? A Study Using Decision Analysis

“…Marshall 24 found that bAP projections give rise to higher effective doses than to PA projections because the majority of irradiated radiosensitive organs within the abdomen, such as the small intestine and others, lie closer to the entrance surface for the AP views in comparison to the PA views.Q In addition, the dense paraspinal musculature of the back will attenuate radiation better than would the subcutaneous fat of the anterior trunk, unless the fat is very thick.…”