Radiation Management in CTO PCI

Carlo Maccia – Francoise MALCHAIR CAATS – Paris (F)

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

INTRODUCTION

• During CTO-PCI procedures patients may be exposed to high doses to the skin resulting in tissue reactions.

• Assessing the Maximum Skin Dose (MSD) to the patient during (or after) these procedures together with 2D dose distribution is essential from patient radiation protection management point of view.

• There exist several software tools (online or offline) aiming at assessing the MSD.

• They are : • commercialized by major X-ray equipment manufacturers • produced by independent companies.

• The capabilities and accuracy of Skin Dose Calculation (SDC) software markedly differ among vendors; and the reporting of the MSD estimate as well as the related accuracy in the Radiation Dose Structured Report (RDSR) is neither systematic nor harmonized.

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

Dosimetry

quantities

displayed

AK rate @ IRP (during the exposure)Cumulative AK @ IRP (post exposure)Kerma-area Product rate (KAP rate) (during the exposure)Cumulative Kerma-area Product (KAP) or Dose-area Product (DAP) (post exposure)Total fluoroscopy time

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

RULE n° 1 : pertinently discriminate among displayed quantities

Isocentre

15 cm

Kerma-area

Product (KAP)

Entrance

Surface Air

Kerma

AK @ Interventional

Reference Point

(IRP)

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

RULE n° 2 : keep an eye on AK@IRP

6

MSD direct measurement devices

MSD direct measurement in practice

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

Software Name References Manufacturer

Dose Map** Bordier et al. 2015 a; Nilsson-Althen and Sandborg 2016 GE

Dosewatch* Gardavaud et al 2018 GE

DTS** Bednarek et al. 2011 ; Rana et al. 2013 ; Rana et al. 2016 CANON

em.dose* Greffier et al. 2017 ; Magnier et al. 2018 ESPRIMED

Radimetrics* BAYER

RDM* Habib Geryes et al. 2018 MEDSQUARE

Dose* Hintenlang et al. 2018 QAELUM

UF-RIPSA*Johnson et al. 2011 ; Borrego et al. 2017 ; Borrego et al.

2018Non-commercial

Khodadadegan et al. 2011 ; Khodadadegan et al. 2013 Non-commercial

FDEIR* Takata et al. 2017 Non-commercial

MCGPU* Badal et al. 2013, Principi et al. 2018 Non-commercial

*offline system - **online system

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

Software Name BSF

Table and the

mattress

attenuation

Ka,r calibration

factor (CF)f-factor Patient model

Dose Map

Logarithmic model

BSF = a ln(area)+b;

per event

Second order

polynomial model vs

kV; per event

N/A

N/A

Elliptical phantoms

Dosewatch BSF AF Single value N/A ICRP phantoms

DTSFrom calibration

measurements; per

event

From calibration

measurements and

corrected for beam

angulation; per event

From calibration

measurements; per

event

Single valueCAESER database patient

modelling

em.dose From literature*

Set by user for

different beam

qualities; per event

Single value set by

userSingle value Elliptical phantoms

RadimetricsNot Available

Single value set by

user

Selectable by

user

Choice between a list of

different phantoms

RDM From literature*

Set by user (PA) and

corrected for beam

angulation; per event

Single value set by

userFrom literature*

Rectangular

parallelepiped with two

half-cylinders on the side

Comparison of BSF, Att, CF, f-factors and patient model by developers

*Benmakhlouf et al 2011; per event11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

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Dosewatch

Skin Dose

DTS - Canon

DoseMap

Radimetrics

MSD software output examples

UF-RIPSA

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

Repeat proceduresradiogenic skin injuries

RULE n° 3 : Ask patient about the age of skin changes

Cumulative KAP or DAPTotal fluoroscopy timeNumber of runsFrame rate

DosimetryIndicators/Quantities

Not relevant for MSD

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

Cumulative KAP or DAP/fluoro time

Cumulative KAP or DAP/fluoro time per procedure

Cumulative KAP or DAP/fluoro time per operator

DosimetryIndicators/Quantities

Relevant for Efficiency Index

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

- DAP value as a dosimetric indicator for CTO-PCI: - (fluoroscopy and acquisition)- (high dose rate/small field size or low dose

rate/large field size)

- Fluoroscopy time has no correlation with MSD

RULE n° 4:STOP USING

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

• If AK @ IRP exceeds the recognized threshold dose value of :

5000 mGy

• Get RDSR of the procedure

• Assess MSD

• Start patient follow-up procedure

RULE n° 5:RELY ON YOUR

MEDICAL PHYSICIST

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin

Occupational Exposure issue

RULE n° 6:Comply with

ALARA

CONCLUSION

• Managing patient radiation protection is technically feasible for CTO-PCI

• The most important physical quantity to monitor is the Maximum Skin Dose (MSD)

• Several Skin Dose Calculation (SDC) software are available nowadays

• They still need to be harmonized

• Collaboration with Medical Physicist is essential, when threshold dose value is exceeded

11th Experts Live CTO – September 13th – 14th , 2019 – Berlin