Gafchromic XR‐QA2 film as a complementary dosimeter for hand‐monitoring in CTF‐guided biopsies

Abstract

Computed tomography fluoroscopy (CTF) is a useful imaging technique to guide biopsies, particularly lung biopsies, but it also has the potential for very high hand exposures, despite use of quick‐check method and needle holders whenever feasible. Therefore, reliable monitoring is crucial to ensure the safe use of CTF. This is a challenge, because ring dosimeters monitor exposure only at the base of one finger, while the fingertips may be exposed to the highly collimated CT beam. In this work we have explored the possibility of using Gafchromic XR‐QA2 self‐developing film as a complementary dosimeter to quantify hand exposure during CTF‐guided biopsies. A glove used in a previous study and designed to contain 11 TLDs was adapted to include Gafchromic strips 7 mm wide, covering the fingers. A total of 22 biopsies were successfully performed wearing this GafTLD glove under sterile gloves, and the IR reported no difficulty or reduction of dexterity while wearing it. Comparison of dose distributions obtained from digitization of the Gafchromic film strips and absolute Hp(0.07) readings from TLDs showed good agreement, despite some positional uncertainty due to relative movement. Per procedure, doses at the base of the ring finger can be as low as 3%–8% of hand dose maximum. Accumulated dose at the base of the ring finger was four times lower than the dose maximum.PACS numbers: 07.57.Kp, 29.40.‐n, 85.25.Pb, 87.57.qp

The use of needle holders in CTF guided biopsies as a dose reduction tool

“…Moreover, individual attitudes toward risk vary between individuals, and concerns over patient safety also play a role. But methods of extremity monitoring during CTF guided biopsies need to be improved, because fingertip dose is not correctly assessed by ring dosimeters …”

“…The median hand dose measured by Buls et al was 0.76 mSv per procedure (maximum 7.3 mSv) . However, finger doses may be 20 times higher than at the back of the hand when side‐handle (SH) manipulation is used …”

“…Intermittent imaging has obvious limitations when dealing with respiratory motion, while needle holders have been associated to decreased tactile feedback and grip, as well as bending of thinner biopsy needles . Because of such limitations, it is likely that interventional radiologists (IRs) will resort occasionally to manual manipulation of the side handle (SH) of the co‐axial guiding needle (side‐handle manipulation), as described by Buls et al This puts the IR's hand very close to the irradiation beam, and may lead to high exposures near the fingertips …”

Technical Note: ID‐card‐size dosimeter based on radiochromic films for continuous personnel monitoring

“…However, the visible darkening of radiochromic films under medium and high radiation doses allows developing both quantitative and qualitative monitoring tools on their basis. In 13, a complementary dosimeter for hand‐monitoring in CTF‐guided biopsies has been proposed. A glove containing Gafchromic XR‐QA2 film strips serves as a means for the immediate visualization of the beam acting on hands.…”

3-D dose distribution for organ dose measurement in CT thoracic exams using Gafchromic™ XR-QA2 films

“…The sensitive layer of the latest Gafchromic TM , unlike its predecessor, contains Bi 2 O 3 to boost the photoelectric effect at low energies [7]. Gafchromic TM XR-QA2 films have also been used for dose measurements in other areas of diagnostic radiology, such as Contrast Enhanced Digital Mammography (CEDM) [14], Computed Tomography Fluoroscopy (CTF) [15], dental Cone Beam CT [16] and in Micturating Cysto Urethro Gram (MCUG) procedures [17], showing satisfactory results. Radiochromic films can be extended from 2-D to 3-D reference dosimetry systems by embedding the sheets of the films between water equivalent plastics designed to either simulate ideal geometrical conditions (square slabs) [18] or even inhomogeneous human-like phantoms, e.g.…”