La radiologia medica

, Volume 115, Issue 1, pp 105–114 | Cite as

Low-dose unenhanced CT protocols according to individual body size for evaluating suspected renal colic: cumulative radiation exposures

  • S. Tartari
  • R. Rizzati
  • R. Righi
  • A. Deledda
  • S. Terrani
  • G. Benea
Uro-Genital Radiology / Radiologia Uro-Genitale

Abstract

Purpose

The aim of this study was to assess the radiation dose of dose-reduced unenhanced abdominal multidetector computed tomography (MDCT) scan protocols for suspected renal colic in patients within normal weight range and overweight-obese patients and to record the cumulative dose of repeated examinations.

Materials and methods

Over a 2-year period, we performed 1,026 unenhanced CT examinations for urolithiasis; among these, 675 were performed on 636 patients referred from the emergency department. Patients were divided into two groups on the basis of body mass index (BMI): normal weight (BMI <25 kg/m2 group 1); overweight and obese (BMI >25 kg/m2 group 2). For patients in group 1 and group 2, the protocols of our 64-row scanner prescribe tube current settings at 70 mAs and 150 mAs, respectively. The dose-length product (DLP) estimated by using the manufacturer’s software was converted into effective dose (ED).

Results

Mean DLP and ED were 177 and 345 mGy/cm and 2.4 and 4.8 mSv for group 1 and group 2, respectively. A subset of 25 patients (3.7%) underwent two or more examinations, with estimated ED ranging from 4.8 to 19.2 mSv.

Conclusions

Although radiation dose is nearly double in overweight-obese patients undergoing MDCT, it remains lower than that delivered by a standard-dose protocol. Patients with flank pain, who are often young, are at increased risk for serial CT examinations. Use of a low-dose protocol is mandatory in both normal-weight and obese patients to minimise radiation exposure.

Keywords

MDCT Low-dose CT Radiation dose Urinary tract 

Protocolli TC diretta a bassa dose in funzione della corporatura del paziente nella valutazione della sospetta colica renale. Esposizione cumulativa da indagini ripetute

Riassunto

Obiettivo

Scopo dello studio è misurare la dose efficace della TC addominale diretta con protocolli a bassa dose dedicati per pazienti di corporatura normale e pazienti obesi con sospetta urolitiasi, registrando inoltre l’esposizione derivante da indagini TC ripetute.

Materiali e metodi

Durante un periodo di due anni abbiamo eseguito 1026 indagini TC per urolitiasi; tra queste, 675 TC sono state eseguite in 636 pazienti provenienti dal Pronto Soccorso (PS). Per ogni paziente è stato calcolato l’indice di massa corporea (BMI) dividendo i pazienti in due gruppi: pazienti di taglia normale (BMI<25 kg/m2, gruppo 1) e sovrappeso-obesi (BMI>25 kg/m2, gruppo 2). Per il gruppo 1 ed il gruppo 2 i protocolli del nostro apparecchio TC 64 strati sono stati impostati rispettivamente a 70 mAs e 150 mAs. I valori di DLP forniti dal software dell’apparecchio sono stati convertiti in dose efficace.

Risultati

La DLP media e la dose efficace media sono risultate di 177 e 345 mGy·cm e 2,4 e 4,8 mSv rispettivamente per il gruppo 1 ed il gruppo 2. Una sottopopolazione di 25 pazienti (3,7%) é stata sottoposta a 2 o più indagini con una dose efficace stimata in un range compreso tra 4,8–19,2 mSv.

Conclusioni

La dose efficace media è doppia nel paziente obeso, tuttavia inferiore rispetto a quella somministrata con un protocollo standard. I pazienti con colica renale, spesso giovani, hanno alta probabilità di essere sottoposti a ripetute indagini TC. L’impiego di un protocollo a bassa dose dedicato sia al paziente normale che al paziente obeso è fondamentale per minimizzare l’esposizione.

Parole chiave

TCMD TC a bassa dose Dose Vie urinarie 

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Copyright information

© Springer-Verlag Italia 2009

Authors and Affiliations

  • S. Tartari
    • 1
  • R. Rizzati
    • 1
  • R. Righi
    • 1
  • A. Deledda
    • 1
  • S. Terrani
    • 2
  • G. Benea
    • 1
  1. 1.Dip. di Diagnostica per Immagini e Radiologia InterventisticaAzienda USL di Ferrara, Ospedale del DeltaLagosanto, FerraraItaly
  2. 2.Clinical Application Specialist CTPhilips HealtcarePhilipsUK

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